ASME Conference Presenter Attendance Policy and Archival Proceedings

2013;():V004T00A001. doi:10.1115/DETC2013-NS4.

This online compilation of papers from the ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2013) represents the archival version of the Conference Proceedings. According to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.

Commentary by Dr. Valentin Fuster

18th Design for Manufacturing and the Life Cycle Conference: Conceptual Design, Manufacturability Analysis, Manufacturing Cost Estimation, and Total Cost of Ownership

2013;():V004T05A001. doi:10.1115/DETC2013-12028.

Early manufacturability feedback is critical for reducing product cost and lead-time. This paper describes a new architecture and platform for authoring and applying manufacturability rules for design. The key step is to define a domain-specific ontology by creating a higher-level semantic language that describes design and manufacturing concepts relevant to specific manufacturing processes. This language has two primary uses; express design in the context of manufacturing and relate manufacturing constraints on design as declarative rules. OWL and Jena (a reasoning engine) are used in the background to reason about specific designs and provide manufacturability feedback in a client-server model. The use of Semantic Web technology makes it easier to augment manufacturability feedback with a query system for the designer that utilizes the same rule knowledge base to answer what-if scenarios. This is implemented using SPARQL and using the CAD design context and so enhances the user experience. This novel approach makes it easier for the domain experts to write or verify rules and the designers to validate concepts before changing the CAD model. This helps in maintaining the independence between the CAD platform and core enterprise knowledge. A pilot study in the sheet metal domain is implemented to demonstrate the steps necessary for complete early manufacturability analysis software and highlights the benefits of this approach.

Topics: Design , Feedback
Commentary by Dr. Valentin Fuster
2013;():V004T05A002. doi:10.1115/DETC2013-12113.

This paper presents a novel interactive motion planning system for assembly/disassembly operations. Our system consists of three layers: interaction layer, learning layer and motion library layer. In interaction layer, user’s manipulation in difficult scenario is liberated by relaxing collision constraints. The resulting path is retracted and connected by random retraction method and BiRRT algorithm. A motion path which successfully passed through the narrow passage or information of geometrical interference in failed case is returned to user. In learning layer, motion primitives corresponding to prior similar scenario are selected by scenario comparison which is based on medial axis, and then transformed to generate new motions. Significant improvement for motion planning of non-convex object in challenging scenarios with narrow passages is obtained by interactive process. The introduction of learning mechanism can reduce global planning time and obtain experiential knowledge.

Commentary by Dr. Valentin Fuster
2013;():V004T05A003. doi:10.1115/DETC2013-12736.

In a time when energy crises loom on the horizon, means for more efficient energy sources are being thoroughly researched. One such area for improvement is in the building sector with the implementation of double skin façades (DSF). With capabilities of relatively rapid and large changes in various aspects of itself, a DSF can respond dynamically to varying ambient conditions. Applying American Society of Heating, Refrigerating and Air-Condition Engineers, Inc (ASHRAE) standards to design a general building model with a standard HVAC system, a comparison can be drawn between different architectural configurations, both with and without DSFs, and a better understanding of how a DSF can affect heat transfer into a building could potentially influence future structural design decisions. Using CAD models, a flow analysis and rudimentary heat transfer can be conducted in a computational fluid dynamics (CFD) software, Fluent which can account factors such as wind speed as well as solar radiation. With the various design applications, the heat load of a building can be reduced by over 15%.

Commentary by Dr. Valentin Fuster
2013;():V004T05A004. doi:10.1115/DETC2013-13070.

The design and manufacture of large scale systems, particularly automobiles, is a process that requires collaboration across multiple disciplines. This collaboration is facilitated through efficient and effective data and knowledge storage and transfer. Specifically, the data associated with the final assembly of the vehicle should be generated, organized, and distributed in such a manner that each user of the data is able to use it effectively. Furthermore, the structure for the assembly data should be robust and reliable such that it fosters consistency among various planners for multiple vehicle platforms that are assembled all around the world. This research aims to develop a centralized data structure for assembly planning information that will allow a global automotive production company to create, relate, and store the necessary information for the assembly of multiple vehicle platforms in various locations, performed by associates that speak multiple languages. This is achieved by first observing the existing business processes of the company and identifying which processes are crucial to the production of vehicles, which processes may be omitted, and what processes need to be added. A data model is developed around these processes that allows multiple users to interact with the data as applicable to his or her duties, and a user interface is developed to demonstrate these interactions. The prototype system is demonstrated and tested.

Commentary by Dr. Valentin Fuster
2013;():V004T05A005. doi:10.1115/DETC2013-13123.

Geometric Dimensioning and Tolerancing (GD&T) Standards have established a language for clear and concise specification of dimensional and geometric variations on manufactured parts. The language includes symbols for tolerance type, tolerance value, datum and reference frames, diameter and material condition modifiers and associativity with geometric entities. Designers use the standard to communicate their dimensional specifications to manufacturing and inspection personnel. However, process planners appear to be less formal in how tolerances are represented in process plans. Typically, they are shown only as dimensional plus/minus values. Datum Reference Frames (DRF) and geometric tolerance symbols are absent. It is believed that the latter are implicit in the set-up and fixturing prescribed in the plan. In this paper we explore how one might extract the implicit information systematically. The motivation for this effort is to verify the consistency of manufacturing tolerances with design specs and to be able to use the same tolerance analysis tools used in design. We discuss three research issues: extracting implied DRFs from set-ups and fixtures; converting plus/minus tolerances to appropriate geometric tolerances; and dealing with transient features — which are features that do not exist on the finished part used for GDT specs by the designer. We propose a new data structure, PCTF (process oriented constraint tolerance feature graph) to facilitate mapping between design and manufacturing tolerances.

Commentary by Dr. Valentin Fuster

18th Design for Manufacturing and the Life Cycle Conference: Design for Mass Customization, Design for Service, and Design for Layered Manufacturing

2013;():V004T05A006. doi:10.1115/DETC2013-12311.

A multi-faceted concept of customizing products and services, mass customization (MC), extends to multiple levels and to wide and diverse approaches and aspects. Although there are many related literature, the principles and technologies of mass customization of cyber-physical systems (CPSs), and in particular cyber-physical consumer durables (CPCDs), have not received enough attention. Unique characteristics of CPCDs make them difficult to be customized by using conventional MC approaches. This paper reports on the conduct and the results of a critical survey towards an in depth understanding of existing MC approaches. As a first step, a comprehensive reasoning model was created, which identified methodology, product life cycle, actors, artifact, and affordances as orthonormal domains of knowledge related to MC. Then, a different classification of MC approaches has been developed in order to provide a better resolution for product life cycle and more explicitly definite MC approaches. The outcome of our survey and analysis shows that although conventional MC approaches offer many applicable principles, none of these approaches, individually, is able to fulfill all the requirements for MC of CPCDs — therefore a novel approach is needed. Development of a novel approach would entail reformulation of applicable principles and generation of new ones. The survey revealed that more focused research is needed to come up with appropriate MC principles that focus on specific families of CPCDs.

Commentary by Dr. Valentin Fuster
2013;():V004T05A007. doi:10.1115/DETC2013-12762.

This paper deals with a study on a method to support the decision on entering business areas in a business model consisting of manufacturing and service. This method divides the business model into business areas by the functions that support a company to decide whether it should enter business areas.

This method prioritizes the areas from the aspects of profit opportunities, barriers to entry, and interactions between the areas. This method reduces the time to decide which business area to enter and reduces the number of examination objects to the number of business areas (n) or fewer from the total number of possible combinations (2 to the 2nd power n).

To confirm the efficiency of this method, we demonstrated two case studies in the IT services industry. In the first case study, from the perspective of a UPS battery supplier, the number of examination objects is 3 when the number of business areas is 11. And the first case study indicates that a suitable strategy for a battery supplier is to concentrate on the strategy of supplying batteries. In the second case study, from the perspective of an IT service provider, the number of examination objects is 10 when the number of business areas is 11. The second case study indicates that a suitable strategy for an IT service provider is vertical integration from software development to data center operation and hardware manufacturing.

Topics: Manufacturing
Commentary by Dr. Valentin Fuster
2013;():V004T05A008. doi:10.1115/DETC2013-13114.

Product-Service Systems (PSSs) are regarded as an attractive business concept for manufacturing companies to enhance the value of their products. For designing an effective PSS, it is important to search for value provision opportunities in the entire product life cycle and offer appropriate services to customers at each opportunity. Because both products and services are included in the design object, PSS designers need to use a broader range of knowledge compared with that required in product design. This study proposes a knowledge management method to support designers in the conceptual design phase of PSS. The effectiveness of the proposed method is demonstrated by application to an example of PSS design.

Commentary by Dr. Valentin Fuster
2013;():V004T05A009. doi:10.1115/DETC2013-13624.

This paper aims to develop quantitative models of customer perception on products and/or services. Prevailing methods often deal with this issue using utility theory, which uses normative models to make rational decisions without considering affective factors. This paper takes another perspective using cumulative prospect theory through how human users’ subjective experience impacts their choice behavior under uncertainty. Toward this end, quantitative measure of customer perception based on cumulative prospect theory and affective influence in terms of parameter shaping based on hierarchical Bayesian model with Markov chain Monte Carlo is proposed. A case study of airplane cabin lighting design is presented to show the potential and feasibility of the proposed method.

Topics: Design , Aircraft
Commentary by Dr. Valentin Fuster
2013;():V004T05A010. doi:10.1115/DETC2013-13663.

Recently, service has been recognized as an effective means to enhance customer satisfaction. The importance of service is widely accepted. Based on this background, the authors of this paper have conducted conceptual research on service design from the engineering perspective. This research series is called “Service Engineering.” In order to achieve a successful service, service providers should maintain service quality and always satisfy their customers. To be specific, the provision of highly reliable service is essential for service providers to survive in their target market. To realize highly reliable products or services, in general, it is an effective approach to prevent failures from occurring in the use phase. In this study, we aim to support service failure analysis in order to minimize the occurrence of failures. This paper proposes a method for analyzing service failure effects in the service design phase. Specifically, we define service failure and propose a procedure to analyze service failure effects with models that are proposed in Service Engineering. The proposed method is verified through its application to a practical case.

Topics: Failure
Commentary by Dr. Valentin Fuster

18th Design for Manufacturing and the Life Cycle Conference: Design for Quality, Robust Design, and Uncertainty Management

2013;():V004T05A011. doi:10.1115/DETC2013-12242.

Today, in order to be competitive in a fierce global car market, higher demands are placed on the Perceived Quality (PQ) of the products. The end customer’s visual impression of fit and finish are one of several factors influencing the overall PQ. When assessing the PQ of split-lines, the assumed geometric variation of the ingoing parts is an important prerequisite for trustworthy visualization and for correct judgments. To facilitate early decision making in conceptual phases, new demands are set on virtual tools and methods to support the engineers.

In this study, a method for early evaluation of the impact of geometrical variation on PQ of split-lines is proposed. Starting from an exterior styling model, mesh morphing techniques have been used to distort the exterior model according to measurement data acquired in running production. Morphing techniques have also been used to adopt previous structural design solutions onto the new styling, in order to make an early assumption of the assembly stiffness.

The used method is described and adopted in an industrial case. The study shows that the presented technique can be used to create continuous and correlated datasets. Non-rigid part behavior can be included in early PQ evaluations, even if final CAD/FEA engineering design models do not yet exist.

Commentary by Dr. Valentin Fuster
2013;():V004T05A012. doi:10.1115/DETC2013-12418.

A robust process is insensitive to the effect of noise variables. Noise variables are the main source for producing variation. Noise variables are included in the outer array in robust design experiment for enhancing robustness. The approach of robust design is to make the process robust (insensitive) to variation due to noise variables. The effect of noise factors can be modelled in a response surface model which helps to determine the settings of the design factors that neutralize the effects of the noise factors and improve robustness. In experimental design the noise factors are assumed fixed value whereas in real world manufacturing noise factors vary randomly. Again for a large scale manufacturing, it is extremely difficult to study robustness using experimentation as there are chances of stoppage of production. In such a situation a simulation-based model can be developed using industrial data to study robustness of a real manufacturing process. This paper proposed a method (a combination of simulation, regression modelling and robust design technique) to study robustness of a hardening and tempering process producing component worm shaft used in the steam power plant. The process capability indices (both univariate and multivariate) are determined based on the model responses. The variation of process performance (process capability values) due to random noise variation is studied using a general purpose process control chart (R-chart). The results show that noise factors in hardening and tempering process are insensitive to manufacturing variation and process capability indices act as a surrogate measure of process robustness.

Topics: Robustness
Commentary by Dr. Valentin Fuster
2013;():V004T05A013. doi:10.1115/DETC2013-12814.

In every manufacturing situation there are geometric deviations leading to variation in properties of the manufactured products. Variation affects the manufacturability, functions and aesthetics of the products. Therefore, a number of methods and tools have been developed during the last 20 years in order to assure the geometric quality and to minimize the effect of variability. These methods and tools have mainly been developed for rigid bodies or sheet metal components.

Plastics or composites have been an increasingly popular material due to their flexible mechanical properties and their relative ease in manufacturing. However, their mechanical properties are introducing challenges that have not often been addressed in the process of geometry assurance. One challenge is to assure that the stresses introduced, as a consequence of non-nominal assembly in the positioning system, are kept well below critical limits during the conditions of use.

In this paper, we are proposing the use of the method of influencing coefficients (MIC) to simulate the distribution of von Mises stresses in assembled components. This method will be compared to the more flexible but computationally much heavier Direct Monte Carlo (DMC) method, which is not suitable for variation simulation due to the large number of runs required for statistical inference.

Two industrial case studies are presented to elicit the need of the proposed method.

Topics: Simulation , Stress
Commentary by Dr. Valentin Fuster
2013;():V004T05A014. doi:10.1115/DETC2013-13389.

Radio Frequency Identification (RFID), as the name suggests, is technology that makes use of radio frequency electromagnetic wave to automatically identify objects. In spite of its broad applications, a RFID system might inherently produce some false and duplicate readings. Such reading data would affect the accuracy of the RFID system and might result in an unreliable performance or even complete unavailability of the system. In this paper, a reading rate-based algorithm is proposed to efficiently clean RFID data for a local business in product tracking. The method takes advantage of the proportional relationship between reading rate of a RFID tag and its distance to the reader to filter among raw data sets. Using the proposed reading rate-based algorithm, the reading accuracy of the RFID system in the local business is greatly improved.

Topics: Waves , Algorithms , Filters
Commentary by Dr. Valentin Fuster
2013;():V004T05A015. doi:10.1115/DETC2013-13600.

For an adaptable product, both configuration and parameter values associated with the configuration can be adapted in the product operation stage to satisfy different requirements. This research aims at developing a new design approach to identify the adaptable product whose functional performance is the least sensitive to parameter variations caused by uncertainties. First different configuration candidates in design and different product configurations in operation stage to satisfy design requirements are modeled by a novel hybrid AND-OR tree. Product/operating parameters associated with configurations are also modeled. A two-level optimization method is developed for identifying the optimal design configuration and the parameter values: design configuration optimization for identifying the optimal design configuration and parameter optimization for identifying the optimal parameter values associated with this design configuration. Case study of an adaptable vibratory feeder is developed to demonstrate the effectiveness of the newly developed robust adaptable design method.

Commentary by Dr. Valentin Fuster

18th Design for Manufacturing and the Life Cycle Conference: Design for Supply Chain

2013;():V004T05A016. doi:10.1115/DETC2013-12464.

Long life cycle products, commonly found in aviation, medical and critical infrastructure applications, are often fielded and supported for long periods of time (20 years or more). The manufacture and support of long life cycle products rely on the availability of suitable parts, which over long periods of time, leaves the parts susceptible to supply chain disruptions such as suppliers exiting the market, allocation issues, counterfeit part risks, and part obsolescence.

Proactive mitigation strategies exist that can reduce the impact of supply chain disruptions. One solution to mitigating the supply chain risk is the strategic formulation of part sourcing strategies (optimally selecting one or more suppliers from which to purchase parts over the life of the part’s use within a product or organization). Strategic sourcing offers a way of avoiding the risk of part unavailability (and its associated penalties), but at the expense of qualification and support costs for multiple suppliers. An alternative disruption mitigation strategy is hoarding. Hoarding involves stocking enough parts in inventory to satisfy the forecasted part demand (for both manufacturing and maintenance requirements) of a fixed future time period. This excess inventory provides a buffer that reduces the effect of supply chain disruptions on the part total cost of ownership (TCO), but increases the total holding cost.

This paper presents a method of performing tradeoff analyses and identifying the optimal combination of second sourcing and hoarding for a specific part and product scenario. A case study was performed to examine the effects of hoarding on both single and second sourced parts. The case study results show that hoarding can contribute to a decrease in the cumulative TCO and a decrease in its variance.

Topics: Cycles
Commentary by Dr. Valentin Fuster
2013;():V004T05A017. doi:10.1115/DETC2013-12587.

With continued emphasis on sustainability-driven design, reverse logistics is emerging as a vital competitive supply chain strategy for many of the global high-tech manufacturing firms. Various original equipment manufacturers (OEMs) and multi-product manufacturing firms are enhancing their reverse logistics strategies in order to establish an optimal closed-loop supply chain through which they can introduce refurbished variants of their products back into the market. While a refurbished product strategy helps to mitigate environmental impact challenges as well as provide additional economic benefits, it is limited to an existing product market, possibly a subset of the existing market, and fails to commercialize/target new markets. In addition to refurbishing, the alternatives available for utilizing End-Of-Life (EOL) products are currently restricted to recycling and permanent disposal. In this work, the authors propose employing a new EOL option called “resynthesis” that utilizes existing waste from EOL products in a novel way. This is achieved through the synthesis of assemblies/subassemblies across multiple domains. The “newly” synthesized product can then be incorporated into the dynamics of a closed-loop supply chain. The proposed methodology enables OEMs to not only offer refurbished products as part of their reverse logistics strategy, but also provide them with resynthesized product concepts that can be used to expand to new/emerging markets. The proposed methodology provides a general framework that includes OEMs (manufacturers of the original product), retailers (distributors of the original product and collectors of the EOL products) and third-party firms (managers of the EOL products) as part of a closed-loop supply chain strategy. The proposed methodology is compared with the existing methodologies in the literature wherein a third-party supplies the OEM only with refurbished products and supplies products unsuitable for refurbishing to another firm(s) for recycling/disposal. A case study involving a multi-product electronics manufacturer is presented to demonstrate the feasibility of the proposed methodology.

Commentary by Dr. Valentin Fuster

18th Design for Manufacturing and the Life Cycle Conference: Emerging Design for X Methods (e.g., Reliability, Maintainability, and Resilience)

2013;():V004T05A018. doi:10.1115/DETC2013-13026.

The design process is driven by a number of requirements and constraints. In developing countries, designers are faced with extra constraints; such as the availability of components in the local market. The availability is not limited to procurement of part from local markets. It is extended to having parts within an acceptable quality. Developing world markets are flooded with a spectrum of varying quality products at different price ranges. Hence, it becomes the designer’s duty to identify the proper components that meets the functional requirements of the system. This paper covers the system/product development process; which is an extensive process, taking into account the reality of the local developing world markets. The paper starts by reviewing the literature on the design for X, and then shows how the design for availability and cost should be incorporated in the design process.

Commentary by Dr. Valentin Fuster
2013;():V004T05A019. doi:10.1115/DETC2013-13325.

Assembly process sheets are formal documents used extensively within automotive original equipment manufacturers (OEMs) to document and communicate assembly procedure, required tooling, contingency plans, and time study results. These sheets are authored throughout the vehicle life-cycle. Further, various customers use these sheets for training, analyzing the process, and line-balancing. In this research, the primary focus is the time studies analysis that is completed using knowledge contained within the assembly process sheets. In this research, a method and software tool are developed to utilize coupling between part descriptions and process descriptions for assembly time studies. The method is realized through the development of a standardized vocabulary for describing work instructions, a mapping from work instructions to MTM codes, and a tool for extracting relevant part information from CAD models. The approach enables process planners to establish part-process coupling, author work instructions using the controlled vocabulary, to estimate assembly time. A prototype system is developed and tested using examples from an automotive OEM.

Commentary by Dr. Valentin Fuster
2013;():V004T05A020. doi:10.1115/DETC2013-13542.

In 2010, high tech industries including computer makers, peripherals manufacturers, and medical equipment manufacturers spent a total of $8 billion on warranty. Reducing warranty costs improves the manufacturer’s profit and helps to reduce the overall cost of the product. An often cited principle is that approximately 80% of the eventual product cost is ‘locked in’ during the very early stages of product development; however, traditional methods of warranty analysis are not well suited to predict the warranty costs during these early stages. Thus, product development personnel need better tools to make good predictions about the warranty costs so that they can make better decisions to reduce those costs earlier in product development. In order to address this gap, previous research defined a warranty prediction framework, which at its core was a warranty event generation engine integrating the disparate data sources available early in the product development process. The objective of this work was to create an event generation model, which would give the probability of occurrence for a warranty event given the length of time of service for the system. The model developed in this work used three data sources: namely, field data, product development data, and engineering judgment data from our industrial partner. The datasets were then combined using a two-stage numerical Bayes method to predict the probability of occurrence of an event. Various test cases were created by using the different datasets as priors and likelihoods. The results were then compared to an actual field data set to understand how well the model performed. It was found that the model performed well and was able to produce a bounded solution. The paper closes by listing out the future research agenda to create a tool for product development professionals that will help them predict warranty costs.

Commentary by Dr. Valentin Fuster
2013;():V004T05A021. doi:10.1115/DETC2013-13606.

The concept of Design for FDA (DfFDA) has a strong basis on the Food and Drug Administration’s (FDA) regulation for medical devices in the Unites States. In fact; an analysis of the factors that impact the time it takes the FDA’s to provide market approval for medical devices, the product design process model, and Design for X (DfX) methods with overlapping FDA objectives lead to the development of DfFDA as a means to increase awareness about regulatory compliance and promote designers to consider the regulations throughout the development process of medical devices. For doing so, the main objective of DfFDA is to provide regulation-focused guidelines to producers of medical devices. An important part of these guidelines and this paper’s major contribution is the development of a prediction model for the FDA’s decision time. Overall, we want this model to become a tool that allows medical device companies to come up with an accurate estimate of a product’s time-to-market after accounting for the FDA’s decision time. In this work, we provide a comparison and discussion on the adequacy of linear regression models and other non-linear models such as parallel and serial tree-based ensembles for prediction the FDA’s decision time.

Commentary by Dr. Valentin Fuster

18th Design for Manufacturing and the Life Cycle Conference: Entertainment Engineering

2013;():V004T05A022. doi:10.1115/DETC2013-12133.

On May 5th, 2007, a six-car stand-up roller coaster Fujin-Raijin II, during a ride, dropped one of its two wheel assemblies from the second car. Losing its balance, the second car tilted to the left by about 45 degrees. The rider in the left side of the front row jammed her head between the passenger support structure and the handrail of the maintenance walkway and was killed instantly. The next day, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT) instructed a nationwide inspection of similar attractions.

Investigations revealed that the main axle had a crack caused by metal fatigue and the owner of the amusement park, bankrupt in 2009, had been running the coaster for 15 years without changing the axle and reporting “in good condition” upon visual inspection only. The applicable law required, and still does, annual testing with magnetic particles, ultrasound, or liquid penetrant. The axle, at the time of its failure, had only about 25% of cross-sectional area remaining intact where the crack had grown. A maintenance worker later reported looseness with the axle fit in the pressure-receiving hole. The fit was originally designed tight to receive the bending force.

People pay and wait in long lines for the excitement of unusual thrill from short amusement rides. The rides take passengers through unusual movements and G-forces to make them scream and laugh. Mechanical parts of the vehicles thus are subjected to unusual loading conditions. Machine design for such rides requires serious design reviews, failure analysis, frequent inspection, and thorough maintenance. Engineering ethics call for amusement park owners’ and workers’ awareness of design and operations for an unusual environment.

Commentary by Dr. Valentin Fuster

18th Design for Manufacturing and the Life Cycle Conference: Integrated Product and Process Development Processes

2013;():V004T05A023. doi:10.1115/DETC2013-12722.

Datum transfer is usually carried out to satisfy requirements of fixture and operation in manufacturing process. Often such requirements are different than the functional requirements used when choosing tolerances during design. Reassignment and recalculation of tolerances are required to evaluate whether a machining scheme can reach the desired design specification. Since a planar feature are widely utilized in datum reference frame, this paper mainly focuses on the transfer of one datum plane to another parallel plane-segment with round or polygonal shape by using 3D Tolerance-Maps. Firstly, a parametric model about two parallel planar features is proposed to describe the geometric properties and spatial relationships between a design datum and a machining datum. Then, based on a variation analysis of plane-to-plane datum transfer, a more elaborate transformation is utilized to relate T-Maps (Patent No. 6963824) with M-Map. Next, several rigid mathematical inequalities are presented to describe the boundaries of primitive and transformed T-Maps for further accumulation and comparison. The largest possible machining tolerances are determined by fitting the M-Map inside the design T-Map. Analytical relations between the machining and design tolerances are extracted from cross-sections through both T-Maps. Lastly, an example is illustrated to show feasibility of the method.

Topics: Machining , Design
Commentary by Dr. Valentin Fuster
2013;():V004T05A024. doi:10.1115/DETC2013-12846.

This paper proposes an adaptive method of planning design project to handle uncertainty with a task option model. The model considers a task option to perform a challenging design or change it to a conservative one which is a backup of it in order to accommodate various risks. A planning problem is formulated under the assumption that a design project and its process consist of multiple task options, each of which corresponds to a component of the product. A project manager decides the switches of the task by checking the design progress at the milestones. A growth curve model of design progress is adopted to predict the design progress for risk assessment. This research also demonstrates a planning example of a student formula car project and discusses the application of the proposed method.

Commentary by Dr. Valentin Fuster
2013;():V004T05A025. doi:10.1115/DETC2013-12922.

Product documentation plays an important role in product creation. Many parts of the documentation are used for manufacturing, assembly and quality assurance processes. Until today the leading document for manufacturing processes is the engineering drawing. With more complex product designs the clarity of the drawings decreases. Modern technologies enable the transition to a paperless manufacturing documentation without the need for expensive licenses. 3D-PDF technology offers a way to provide manufacturers with 3D-CAD models containing the appropriate product manufacturing information.

In this paper a generative document that provides only the essential information for certain manufacturing steps is presented. 3D-PDF technology is used to present the results to the machinist. The recommended documentation provides two different views: the input and output status of a product at a specific manufacturing station. Those views are created automatically from the ERP database containing manufacturing knowledge of the product. The presented models are supplemented with general information, e.g. material, designer, general tolerances. The limitation on necessary information for only one manufacturing step at a time increases the comprehensibility of the product documentation and thus accelerates the manufacturing process and improves product quality.

Topics: Manufacturing
Commentary by Dr. Valentin Fuster
2013;():V004T05A026. doi:10.1115/DETC2013-13006.

Global collaboration is now a key for enterprises to rapidly achieve their worldwide successes. During the rapid expansion of their business, many challenges are emerging, e.g., novice training, knowledge transferring, intellectual property (IP) protection. This paper presented an effective approach for gaining new knowledge in a design project through reverse engineering by using Environment Based Design (EBD) methodology. The case study used in this paper was designed to demonstrate how design knowledge can be assimilated by using the proposed approach. A graduate student, without any aerospace design knowledge and experience, was presented with a sentence extracted from a statement of work of a student capstone project in the aerospace engineering department of École Polytechnique de Montréal. Within a month, the graduate student designer was able to deliver a conceptual design solution including product life cycle analysis, with only public resources at his disposal. The results were then evaluated by experts in aerospace who have collectively overseen the project for many years, on how much knowledge the student had assimilated. A comparison, between the student designer and other novice designers from the project, was given thereafter. The assessment turns out promising and inspiring in terms of the knowledge assimilation for a novice within such a short time. In other words, the effectiveness of the presented approach has been validated. This is a feasible attempt to significantly shorten the time and minimize the efforts for novice training and knowledge transferring in education and industry, especially when a firm is expanding their global business.

Commentary by Dr. Valentin Fuster
2013;():V004T05A027. doi:10.1115/DETC2013-13270.

Chronic wound assessment and analysis has long been a major healthcare issue. Chronic wound management and treatment cost billions of dollars each year. The research to alleviate the burden of non-healing wounds and predicting when they will heal is progressing at incremental pace. Characteristics of a chronic wound are unique to both the patient and wound itself. Like a fingerprint, each wound has a unique set of properties that tell a story about its health and viability. Although each person’s wound is individual, there are a few underlying pathologies that are common amongst all wounds. For example, all wounds have a definite surface area, depth, and temperature at any given time. By knowing these common characteristics across all wounds, we can use both historical data and collected data to determine wound healing patterns and wound healing rates. The purpose of this study is to develop an algorithm that uses photography and statistical modeling to predict an approximate wound healing rate for lower appendage wounds. We focus on lower appendage wounds with a depth of 1–2 mm because lower appendage wounds account for approximately 70% of wounds seen at wound clinics.

Commentary by Dr. Valentin Fuster

18th Design for Manufacturing and the Life Cycle Conference: Life-Cycle Decision Making

2013;():V004T05A028. doi:10.1115/DETC2013-12294.

Design reviews are typically used for three types of design activities: 1) identifying errors, 2) assessing the impact of the errors, and 3) suggesting solutions for the errors. This experimental study focuses on understanding the second issue as it relates to the number of errors considered, the existence of controls, and the level of domain familiarity of the assessor. A set of design failures and associated controls developed for a completed industry sponsored project is used as the experimental design problem. Non-domain individuals (students from an undergraduate psychology class), domain generalists (first year engineering students), and domain-specialists (graduate mechanical engineering students) are provided a set of failure modes and asked to estimate the likelihood that the system would still successfully achieve the stated objectives. Primary results from the study include the following: the confidence level for all domain population decreased significantly as the number of design errors increased (largest p-value = 0.0793) and this decrease in confidence is more significant as the design errors increase. The impact on confidence is less when solutions (controls) are provided to prevent the errors (largest p-value = 0.0334), the confidence decreased faster for domain general engineers as compared to domain specialists (p = <0.0001). The domain specialists showed higher confidence in making decisions than domain generals and non-domain generalists as the design errors increase.

Topics: Design , Errors
Commentary by Dr. Valentin Fuster
2013;():V004T05A029. doi:10.1115/DETC2013-12639.

Design for End of Life (DfEOL) recovery is a complex process that requires consideration of various design aspects including design for product life extension, design for reliability, design for disassembly, design for components reuse, and design for recyclability. There is a need for an analytical tool that helps designers integrate all these design aspects together and moreover investigate the impact of design features on the recovery network. The designer needs to predict the variability that design features bring into the reverse logistics network, including the variability in the amount, quality and timing of return flows and uncertainty in the remanufacturing operations such as disassembly time. In addition to the product design, the EOL recovery system performance is also affected by human decision making. The willingness of customers to keep used products in storage, the qualitative criteria used by remanufacturing companies to sort and categorize the returned used products and the manual disassembly operations influenced by the operator’s cognitive biases are examples of human decision making processes that impact product recovery. The nonlinear character of reverse logistics system along with the dynamic complexity as a result of uncertainties and cognitive biases are particularly troublesome. This paper establishes a simulation-based System Dynamics (SD) model of product life cycle to check interrelationship among product design features and their impacts on the amount, quality and timing of the return flows to the waste stream. The complex product take back process and recovery operations are modeled. Designers could use the results of the model to compare different design scenarios and to receive information about what design features bring problems or create opportunities for EOL recovery.

Commentary by Dr. Valentin Fuster
2013;():V004T05A030. doi:10.1115/DETC2013-12701.

The aim of this paper is to study the impact of public government policies, fuel cell cost, and battery cost on greenhouse gas (GHG) emissions in the US transportation sector. The model includes a government model and an enterprise model. To examine the effect on GHG emissions that fuel cell and battery cost has, the optimization model includes public policy, fuel cell and battery cost, and a market mix focusing on the GHG effects of four different types of vehicles, 1) gasoline-based 2) gasoline-electric hybrid or alternative-fuel vehicles (AFVs), 3) battery-electric (BEVs) and 4) fuel-cell vehicles (FCVs). The public policies taken into consideration are infrastructure investments for hydrogen fueling stations and subsidies for purchasing AFVs. For each selection of public policy, fuel cell cost and battery cost in the government model, the enterprise model finds the optimum vehicle design that maximizes profit and updates the market mix, from which the government model can estimate GHG emissions. This paper demonstrates the model using FCV design as an illustrative example.

Commentary by Dr. Valentin Fuster
2013;():V004T05A031. doi:10.1115/DETC2013-13529.

Heavy duty machines consume a tremendous amount of energy during their life cycle. Therefore, designing an energy efficient machine is of great importance. This paper presents a method for the comparative life cycle assessment (LCA) of two different types of press machines: servo press and flywheel press to understand quantitatively the environmental emissions during their life cycles. To make a fair comparison of the two machines, the same amount of production is used as the basis for comparison. Assessment scopes and boundaries are defined first, then detailed product structures and manufacturing processes are investigated. After data collection from visiting enterprises, related project reports, academic papers, and commercial software databases, analysis of the life cycle inventory is performed. Comparative inventory tables for each life cycle stages and whole life cycle are presented. The results of the study can be used for decision making during the product purchase, planning and design process.

Commentary by Dr. Valentin Fuster
2013;():V004T05A032. doi:10.1115/DETC2013-13680.

The Life Cycle Assessment (LCA) is a method to measure the environmental impact of a product’s life stages from the cradle to the grave, and is widely used for packaging sustainability. Although many successful applications using LCA have been reported, the current state of LCA tools still has many limitations. For example, it is difficult to select the best design among the LCA results of design sets. Moreover, the LCA tool cannot implement a decision maker’s preference into the process easily.

To overcome these limitations, we developed a decision making tool using LCA for packaging sustainability. First, Pareto Active Set Selection (PASS) method is proposed to find Pareto Front of packaging options. Additionally, Design Preference Function (DPF) is introduced to implement the designer’s preference for selecting the best packaging options. Case studies are presented to demonstrate this decision making tool.

Commentary by Dr. Valentin Fuster

18th Design for Manufacturing and the Life Cycle Conference: Sustainable Design and Manufacturing

2013;():V004T05A033. doi:10.1115/DETC2013-12077.

Sustainable design and engineering is an important topic, yet it is under-represented in educational institutions; moreover, it must be taught to practicing professionals, not just students. A free online system has been created to address both problems at once, providing educational materials for educators and also providing a self-paced program for professionals or students to earn a certificate in sustainable design. Called the Autodesk Sustainability Workshop, it is a collection of video tutorials and supporting materials (PDF reference guides, slide decks, quizzes, and other resources) that can be used either by individuals themselves or by educators (either in schools or the workplace) to learn principles and practical skills related to green design, mechanical engineering, and building science. Its dozens of video tutorials span the range from introduction to fundamental principles in sustainability, to specific operation of analytical software tools such as FEA and energy modeling. All videos are on focused topics and of short duration (typically 3–6 minutes) so they can be inserted into curricula as educators see fit, not forcing a full curriculum structure. For self-guided learners, or educators who desire a full curriculum, an interactive structure provides quizzes along with the learning resources; upon successful completion, they lead up to a certificate in green design. Currently there is only one certificate, in basic building science; future releases will expand the certificate program to sustainable product design as well, since many of the learning resources are on these topics. For content not covered by the certificate program, the website’s information architecture suggests a multi-threaded approach to learning sustainable design. As three-quarters of a million people around the world have already viewed content from the site, this self-directed online learning system is proposed to be a highly scalable method of providing sustainable design and engineering education.

Commentary by Dr. Valentin Fuster
2013;():V004T05A034. doi:10.1115/DETC2013-12104.

Design for sustainability often considers three potentially competing objectives in economic, ecological, and social sustainability. In general, business success hinges on economic sustainability, while ecological and social concerns are treated as secondary objectives for marketing or political purposes. Previous research has shown that there is a tradeoff among these sustainability objectives regarding design decisions that include tolerances and material choices, and different market- or policy-driven incentives may result in different optimal design decisions. This study presents and demonstrates an approach for evaluating legislative opportunities that may internalize ecological and social objectives into the economic objectives of product-developing firms, using the case study of an automotive body panel. Modeling and simulation tools from Computer Aided Tolerancing (CAT), Life Cycle Assessment (LCA), and design optimization are combined using a novel framework to show how sustainability-driven government policies such as taxation may influence design decisions and sustainability outcomes.

Commentary by Dr. Valentin Fuster
2013;():V004T05A035. doi:10.1115/DETC2013-12219.

Charcoal made from agricultural waste (AWC), intended for use in developing countries, has the potential to be a cooking fuel with health, economic, and environmental benefits. Investigations were undertaken to integrate the technical understanding of the fuel with the real-world context in which it may be produced and used. Multiple formulations of AWC were studied to understand the impact of raw material variation on charcoal briquette emissions. A key finding is the viability of manure as a binder, which should improve AWC production costs and proliferation. In Nicaragua, AWC emissions, end user interest, and producer economic viability was examined. Emissions of AWC appear to be similar to or less than wood and wood charcoal. End user interest seems moderate, a positive outcome given the lack of charcoal usage in the region studied. Based on the outcomes of pilot production, development of the manufacturing system must account for local preferences.

Commentary by Dr. Valentin Fuster
2013;():V004T05A036. doi:10.1115/DETC2013-12267.

As sustainable building design practices become more prevalent in today’s construction market, designers are looking to alternative materials for novel design strategies. This paper presents a case study comparing the sustainability performance of cross laminated timber (CLT) and reinforced concrete. A comparative sustainability assessment of cross laminated timber and concrete, considering economic, environmental, and social aspects was performed. Environmental impact is measured in terms of CO2 equivalent, economic impact is measured with total sector cost (including sector interdependencies), and qualitative metrics were considered for social impact. In order to conduct an accurate performance comparison, a functional unit of building facade volume was chosen for each product. For this paper, several end-of-life strategies were modeled for CLT and concrete facades. To understand environmental, economic, and social impact, three different scenarios were analyzed to compare performance of both CLT and concrete, including cradle to gate product manufacturing, manufacturing with landfill end-of-life, and manufacturing with recycling end-of-life. Environmental LCA was modeled using GaBi 5.0 Education Edition, which includes its own database for elements including materials, processes, and transportation. To compare the economic impact, Carnegie Mellon’s EIO-LCA online tool is used. Finally, social life cycle impact was considered by identifying process attributes of both products that affect the social domain. Based on this analysis, the use of CLT has a significantly lower environmental impact than concrete, however there are additional costs.

Commentary by Dr. Valentin Fuster
2013;():V004T05A037. doi:10.1115/DETC2013-12599.

Innovation has been touted as a means toward providing sustainability. Innovations in materials, manufacturing, and product design can lead to a reduction of global environmental impacts while helping to realize the goals of a sustainable society. This research aims to explore whether or not product functionality has an effect on environmental impact and if the flow of energy, materials, and signals (EMS) have an effect on product environmental impact. Innovative and common products are identified and life cycle assessment is performed for each product at the component level. Using function impact matrices, the environmental impacts of the product components are propagated back to the functional level, where their impacts are compared. The innovative products of the comparisons conducted appear to be more environmentally impact; more work must be done to understand whether the result is generalizable. The intended use of this research is during the conceptual design phase when little is known about the final form of a product. With approximate impacts of functions known, designers can better utilize their design efforts to reduce overall product environmental impact.

Commentary by Dr. Valentin Fuster
2013;():V004T05A038. doi:10.1115/DETC2013-12606.

Creating a new recycling system generally suffers from the lack of a coordinated group of stakeholders rather than technical issues of treatment, or available recyclable deposit. Value chain concept and methods has assumed a dominant position in studying industry from management and coordination point of view. Decision support methods using value chain require the acquisition of data from various existing corporate databases or data warehouses. As an effort in developing a methodology and in result of conducting a national industrial recycling chain in France, this study proposes a general value chain design approach which provides a new direction for research and application of value chain from scratch for multi-stakeholder industrial systems. This paper introduces value chain design as a way to determine, model, and analyze and evaluate the industrial ecosystems, in order to generate future scenarios and provide evaluation criteria for decision makers.

Commentary by Dr. Valentin Fuster
2013;():V004T05A039. doi:10.1115/DETC2013-12974.

During past years several eco-design methodologies have been previously defined but none can be easily integrated in the traditional design process of manufacturing companies. This paper wants to overcome this lack and aims to define a methodology, called G.EN.ESI, to help also those designers without a specific know-how on eco-design, during the development of sustainable products. The methodology has been also contextualized in the traditional product design process, re-engineering this one with new input/output data, actors and specific tools, to demonstrate the applicability in real contexts.

The re-engineered process is supported by a new set of integrated software tools, called G.EN.ESI platform. It is made of four tools for the definition of the product life cycle model, two tools for the evaluation of the environmental impact and Life Cycle Cost and a tool to guide the decision-making process during the re-design phase of a product. Furthermore, a web module to retrieve the necessary data from the supply chain subjects has been defined. Finally, the link with the CAD and PLM systems is proposed to increase the usability.

Commentary by Dr. Valentin Fuster
2013;():V004T05A040. doi:10.1115/DETC2013-12975.

Next generation jet engine technologies are typically driven by performance, value and environmental challenges, and appropriate technologies are developed in international research programs. One on-going engine component technology project at an aerospace component manufacturer aims to develop an engine with less fuel consumption. A likely consequence is higher pressure in the core engine, which leads to higher temperature. One way to handle the higher temperature is using a more advanced Ti-alloy for the product component, which will render a different sustainability profile. One weakness in current decision situations is the inability to clarify and understand the “value” and “sustainability” implications compared to e.g. performance features of concepts. Both “value” and “sustainability” include a rich set of features important for successful introduction of new products and product-service solutions to the market. The purpose with this research is to provide decision support for companies in early development phases for assessment of value and sustainability consequences over product-service system lifecycles.

A workshop was held with the aerospace component manufacturer and a value chain partner focusing on material handling, to: i) get a better understanding of activities, flows and ownership related to the studied materials at the two companies, ii) to understand the companies’ perspective at new suggested scenarios with regard to these materials, and iii) define relevant scenarios to look into more in depth from a sustainability and value perspective. Three different scenarios were developed with differences in ownership, responsibilities and value streams. It is therefore essential to be able to quickly assess and optimize consequences of such alternative scenarios.

Based on the workshop experiences and scenarios, a modeling and simulation approach to assess sustainability and value consequences for the scenarios is proposed. The sustainability consequences are based on a sustainability life cycle assessment and a risk assessment. Key features of the proposed tool include: consideration of the time dimension, societal sustainability consequences, risk assessment, company value assessment, and cost/revenue perspectives.

Commentary by Dr. Valentin Fuster
2013;():V004T05A041. doi:10.1115/DETC2013-13048.

ShapeSift is a framework for supporting sustainability-based decision making during selection of similar previous designs from part repositories. Our framework is designed for 3D part repositories that contain metadata pertaining to materials and manufacturing processes as well as the functionality of a given part. To demonstrate the usefulness of the proposed framework we develop an example multi-dimensional visualization that encodes part similarities as well as a calculated environmental sustainability indicator. This visualization is incorporated in a prototype interface that focuses on enhancing the intuitiveness of the exploration process by the use of sketch-based retrieval.

Commentary by Dr. Valentin Fuster
2013;():V004T05A042. doi:10.1115/DETC2013-13074.

The recent proliferation of electronic products has led to a strong unmet need for understanding environmental implications of new technologies. According to Nielsen, 66% of Americans ages 24–35 own a smartphone, providing strong evidence that this technology can be considered ubiquitous. However, a majority of users and service providers are not sensitive to energy implications of data usage. As parameters affecting data delivery and usage are primarily driven by user behavior, this study is focused on using empirical data to investigate its correspondence to energy footprint. A large cohort of smartphone users (n = 21,853) and the means for which data is accessed, i.e. via 3G/LTE or WiFi, is examined to develop a model for estimating the energy cost of the various modes of data usage. Finally, alternate business scenarios are developed through simulating behavior change in cohorts based on existing data and then assessed with regards to economic and environmental efficiencies.

Commentary by Dr. Valentin Fuster
2013;():V004T05A043. doi:10.1115/DETC2013-13310.

The overarching goal of the research is to determine the relationship between light-weighting and the life cycle environmental burdens of a rocket system. Light-weighting is done by replacing traditionally metal components with carbon fiber reinforced polymer components. This paper documents a preliminary analysis of the environmental burdens of a rocket, considering rockets of different sizes and propellant combinations. The purpose of the analysis is to first determine if such a relationship exists, and second to determine which components of the rocket most significantly influence the life cycle environmental burdens. The analysis found that a small change of about 0.15–0.3% in the structural mass can decrease embodied energy and carbon dioxide of the rocket by about 5.2% and 5.0%, respectively. Furthermore, the overall propellant load of the rocket decreases by 5.7%, while the overall structural mass decreases by 6.4%. Though there are small differences as to the extent to which light-weighting reduces environmental burdens depending on propellant combination, it is shown that there is a general reduction in life cycle environmental burdens when a rocket is light-weighted.

Topics: Rockets
Commentary by Dr. Valentin Fuster
2013;():V004T05A044. doi:10.1115/DETC2013-13350.

Sustainable product design plans the entire life cycle of a product from its raw material selection, conceptual and structural formation, manufacturing processing, and usage to its end-of-life, reuse, and recycle. The product design needs the sustainable knowledge and proper tools. Current computer-aided design systems are insufficient to represent complex relationships of product functions, structures and life cycle options. It is required for design tools to support product life cycle planning with multi-objective optimal solutions. In this paper, our experience in design of a wheelchair is used as an example to discuss the need of design tools. The aim is to define ideal tools for design of sustainable products.

Commentary by Dr. Valentin Fuster
2013;():V004T05A045. doi:10.1115/DETC2013-13385.

For sustainability of environment, legislations in EU, USA, Japan and Australia require manufacturers to take back their products at the End of Life (EOL) and recycle them. The concept of 6R (reduce, reuse, recycle, recover, redesign and remanufacture) is very important for this issue, while reuse has the highest energy and material recovery efficiency. In this study, an integrated product information model has been developed in UML to provide necessary information for any future decision making activities in the EOL stage, such as the replacement analysis of any used part or subassembly.

This product information model represents not only product structure but its function, behavior, and their associations in different abstract levels to support replacement analysis of an existing component with a new or a used component available to company. This representation schema provides necessary information for any future decision making activities in the EOL stage, such as the replacement or reuse of any part or subassembly. In an analysis of replacement for a faulty component with a used or new component, this model provides all of the associations of the existing artifact with other artifacts and the environment, not just functional and space requirements, and the relevant modification(s) of the associated objects has to be verified.

Commentary by Dr. Valentin Fuster
2013;():V004T05A046. doi:10.1115/DETC2013-13415.

Consumer requirements for products vary dynamically based on the change of technologies, social influence, individual taste, etc. A sustainable product should meet customer requirements in its lifecycle. Different methods and techniques have been proposed to find possible changes of product needs or customers’ preferences. This paper introduces an agent-based technique to address the change of product requirements. Major contribution of the proposed method is to embed customers’ preference in the analysis of product performance using agent interactions. Using the combination of Quality Function Deployment (QFD), agent-based modeling and data mining methods, customers’ preference trends related to elements and functions of product are simulated. The prediction period is flexible based on estimated product lifecycle. The proposed method is compared with other techniques in a case study.

Commentary by Dr. Valentin Fuster
2013;():V004T05A047. doi:10.1115/DETC2013-13575.

Within the framework of sustainability in manufacturing industry, product lifecycle design is a key approach for constructing resource circulation systems of industrial products that drastically reduce environmental loads, resource consumption and waste generation. In such design, designers should consider both a product and its lifecycle from a holistic viewpoint, because the product’s structure, geometry, and other attributes are closely coupled with the characteristics of the lifecycle. Although product lifecycle management (PLM) systems integrate product data during its lifecycle into one data architecture, they do not focus on support for lifecycle design process. In other words, PLM does not provide explicit models for designing product lifecycles. This paper proposes an integrated model of a product and its lifecycle and a method for managing consistency between the two. For the consistency management, three levels of consistency (i.e., topological, geometric, and semantic) are defined. Based on this management scheme, the product lifecycle model allows designers to evaluate environmental, economic, and other performance of the designed lifecycle using lifecycle simulation.

Commentary by Dr. Valentin Fuster

2013 ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Autonomous Systems and Ambient Intelligence

2013;():V004T08A001. doi:10.1115/DETC2013-12256.

In this paper, we present an omnidirectional artificial landmark model and a robust artificial landmark recognition algorithm for indoor mobile robot positioning. The landmark model encodes identities with nested circles in black and white, which provides stable edge response and enables strong tolerance to various lighting conditions and perspective distortions. The corresponding positioning system uses a single upward-facing webcam as the vision sensor to capture landmarks. To address the effect of the lighting and sensing noise, the topological contour analysis is applied to detect landmarks, and the dynamic illumination adjustment is used to assist landmark recognition. Based on the landmark recognition, the absolute position of the camera in the environment is estimated using a trilateration algorithm. The landmark model and positioning system are tested with a mobile robot in a real indoor environment. The results show that the purposed technique provides autonomous indoor positioning for mobile robots with high robustness and consistency.

Topics: Design , Mobile robots
Commentary by Dr. Valentin Fuster
2013;():V004T08A002. doi:10.1115/DETC2013-12260.

This paper focuses on the speed and yaw control problem for an underactuated unmanned surface vessel (USV) with only two propellers navigating through multiple way-points using the line-of-sight (LOS) algorithm. The speed and yaw dynamics are transformed into a cascaded nonlinear system that can be reduced to the stabilization control problem of the surge and yaw subsystems. The proposed surge speed controller uses a distance and heading error feedback control to vary its speed accordingly while the heading subsystem is stabilized via a finite-time controller. Comparisons of the traditional yaw rate stabilization control techniques are made with the proposed finite-time controller and shown to be inferior to the finite-time controller in terms of convergence rate and robustness. The stability and effectiveness of the proposed control system is demonstrated and validated by simulation results of a modeled kayak.

Commentary by Dr. Valentin Fuster
2013;():V004T08A003. doi:10.1115/DETC2013-12313.

In our paper we present a virtual test environment for self-optimizing systems based on mutant based testing to validate user tasks of a real-time operating system. This allows the efficient validation of the code coverage of the test cases and therefore helps to detect errors in order to improving the reliability of the system software.

Technically we are able to run and test the software on both systems. By writing application software and setting up the virtual test environment properly, we define our test cases. To validate the code coverage for our test cases, we use the approach of mutant based testing. By running this mutated code on our virtual prototype in the virtual test environment, we are able to efficiently validate the code coverage and are able to detect bugs in the application code or detect dead code that is not executed. Finding non-executing code leads to redefinition of our test cases by either changing the test environment or the application code in the case of dead code.

We implemented the virtual test environment on top of the third party low cost VR system Unity 3D, which is frequently used in entertainment and education. We demonstrate our concepts by the example of our BeBot robot vehicles. The implementation is based on our self-optimizing real-time operating system ORCOS and we used the tool CERTITUDE(TM) for generating the mutations in our application code. Our BeBot virtual prototype in our virtual test environment implements the same low-level interface to the underlying hardware as the real BeBot. This allows a redirection of commands in ORCOS to either the real or the virtual BeBot in order to provide a VR based platform for early software development as well as ensures comparable conditions under both environments.

Our example applies a virtual BeBot that drives through a labyrinth utilizing its IR sensors for navigation. The mutant based testing checks if all situations implemented by the software to navigate through the labyrinth are covered by our tests.

Commentary by Dr. Valentin Fuster
2013;():V004T08A004. doi:10.1115/DETC2013-12765.

This research explores how different compositions of Individuals with Disabilities (IwDs) affect the dynamics of crowd movement. In particular, we consider IwDs such as individuals on manual and electric wheelchair, with vision loss and other mobility impairments to better understand the impacts that the compositions of individuals with various types of disabilities will bring on the mobility of the crowd at various structural elements of a built environment such as hall way, door way, and stairwells. While currently available video tracking technologies provide options for primitive macroscopic and microscopic analysis of a crowd, they lack the ability to analyze detailed navigational information of each focused group such as IwDs with varying types of disabilities. This paper provides an approach that exploits ARToolKitPlus libraries and Power-over-Ethernet high speed cameras along with augmented reality elements to track navigational patterns at individual level in a crowd. Preliminary results demonstrate the feasibility of the proposed system to track individual tracking of navigational patterns.

Commentary by Dr. Valentin Fuster
2013;():V004T08A005. doi:10.1115/DETC2013-12878.

The paper describes the results of a research activity on the design of a positioning system which includes both a physical 3-DOF and virtual platforms which carries out a Desktop Haptic Interface (DHI). The positioning system allows the user to interact with a virtual shape through a combination of linear and rotation motions, some of them driven by the user and some driven by the virtual shape. On the other hand, by rendering a physical 2D cross-section through the DHI permits the assessment of virtual prototypes of industrial products with aesthetic value. Typically, virtual objects are modified several times before reaching the desired design, increasing the development time and, consequently, the final product cost. The desktop haptic system (which includes the positioning system and the DHI) that we propose here, will reduce the number of physical mockups during the design process allowing designers to perform several phases of the product design process continuously and without any interruption. In particular the system is developed with the aim of supporting designers during the evaluation of the aesthetic quality of a virtual product.

Topics: Haptics , Shapes
Commentary by Dr. Valentin Fuster

2013 ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Bio-Mechatronics - Medical Devices and Technologies

2013;():V004T08A006. doi:10.1115/DETC2013-12592.

Nowadays, upper-limb injury or impairment represent a widespread problem, related to sport accidents or traumas, surgery operations, stroke and so on. The typical approach to the rehabilitation is one or more physiotherapy sessions, to restore muscular mass and strength. Despite this, over the years, several works proposed innovative solutions, including electromechanical orthoses, which work in relation to the muscular activity, measured by techniques such as superficial electromyography (sEMG). Yet, these systems are still far from commercialization because of their cost, complexity and difficulties in using. A currently unmet need regards the ability of the therapist to control and manage data through a remote interface, by exploiting some of the latest technological resources on the market (smartphones, tablets). The present works aims at designing an upper-limb rehabilitation system, based on an orthosis, sEMG wireless sensors and a dedicated software architecture to overcome these limitations. This will lead to an important change of perspective in physiotherapy procedures since data collection and correlation will produce innovative medical protocols, addressed to people affected by several types of injury or impairment.

Topics: Sensors , Design , Orthotics
Commentary by Dr. Valentin Fuster
2013;():V004T08A007. doi:10.1115/DETC2013-13337.

Biological tissues are plastic with respect to the mechanical environment to which they are exposed. This makes them able to modify their architecture and inner structure in order to respond to different loading conditions with the smallest biological effort (functional adaptation). As a result, tissues can optimally adapt their structures to the task they have to perform.

Based on these concepts, a kinetic model of the ankle joint has been recently developed. The tibio-talar relative motion was obtained by imposing the congruence maximization as a biological optimum throughout the entire flexion range.

The aim of this work is to investigate the applicability of the proposed approach to the knee and to evaluate the weight of the meniscal contribution to the global femoro-tibial congruence.

Topics: Modeling , Knee
Commentary by Dr. Valentin Fuster
2013;():V004T08A008. doi:10.1115/DETC2013-13402.

In several applications, such as the design and setting of prostheses, orthoses and exoskeletons, and the multibody modelling of the lower limb, it is sometimes necessary to approximate the spatial motion of human joints to a rotation about a fixed axis. The identification of these axes can be particularly difficult at the ankle joint, where two different articulations are observed, namely the tibio-talar joint (connecting the tibia and talus) and the talo-calcaneal joint (connecting the talus and calcaneus). Thus, the ankle requires two distinct axes to be identified in order to correctly describe the joint motion. A new technique is proposed here for the identification of the tibio-talar and talo-calcaneal rotation axes. The technique is based on a particular use of the Burmester theory and exhibits several advantages: the talus motion is not required, and only the tibia-calcaneus motion is needed; the identification of both rotation axes is simultaneous and thus the identification accuracy of both axes is independent; the method is not based on optimization techniques and thus it does not require the definition of an objective function; it is robust with respect to experimental inaccuracies; it makes it possible to obtain the talus motion, even if it could not be measured during the experimental session. The technique reveals particularly useful during in vivo measurements based on skin markers or other non-invasive measures, since the talus motion cannot be obtained from skin measurements. An application example is shown by means of experimental data measured on an ankle specimen.

Topics: Rotation
Commentary by Dr. Valentin Fuster
2013;():V004T08A009. doi:10.1115/DETC2013-13622.

We used the method of Bi-directional Evolutionary Structural Optimization (BESO) to optimize the cement placement in finite element (FE) models of osteoporotic femur specimens. Two different initial conditions, i.e. no initial cement and fully cemented, were used and both converged to the same optimal cement pattern. On average, BESO predicted that, if optimized, augmentation with only 18.6ml of cement will result in 100% increase in the yield load of the models. Simulations also showed a linear relationship between the volume of the cement and the models’ stiffness and yield load. Models initially filled with cement had a much more uniform stress distribution among the cemented elements when optimized, compared to the starting configuration. Results suggest that restoring the mechanical properties of osteoporotic femurs is possible with minimal and, therefore, potentially safe volumes of cement.

Commentary by Dr. Valentin Fuster
2013;():V004T08A010. doi:10.1115/DETC2013-13636.

We report the results of planning and experimental validation of femoroplasty — augmentation of mechanical properties of the bone using polymethylmethacrylate (PMMA) bone cement injection — on osteoporotic femurs. For six pairs of osteoporotic femurs, finite element (FE) models were created using computed tomography (CT) scan data and an evolutionary method was used to optimize the cement pattern in one of the models from each pair. Using a particle method and the CT data, cement diffusion was modeled for several hypothetical augmentations and the one most closely matching the optimized pattern was chosen as the best plan. We used intra-operative navigation and a custom-designed injection device to deliver the cement into the bones precisely according to the plan. All femurs were then tested mechanically in a configuration simulating a fall to the side. Augmentation with this technique resulted in an increase in the yield load (28%) and yield energy (142%) compared to the control specimens, while only 9.8ml of cement was injected on average. Results support our hypothesis that significant improvements in the mechanical properties of osteoporotic femurs can be achieved by using minimal, and hence safe, amounts of PMMA bone cement.

Commentary by Dr. Valentin Fuster

2013 ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Cyber-Physical Systems and Hybrid Systems

2013;():V004T08A011. doi:10.1115/DETC2013-12652.

Based on our previous work on Mobile Actuator and Sensor Network, Applied Fractional Calculus, Sensor Networks and BUMMPEE (Bottom-Up Modeling of Mass Pedestrian flows implications for the Effective Egress of individuals with disabilities), a general framework is proposed for modeling and managing Mass Pedestrian Evacuations (MPE) in this paper. A distinctive feature compared with previous work is the incorporation of Individuals with Disabilities (IwDs) in understanding modeling and control of mass pedestrians evacuations. Networked Segway Supported Responders (NSSR) have been firstly employed in the research of modeling and control/managing problem of crowd pedestrians as mobile sensors and mobile actuators. Future simulation and experimental results will be referenced for public policy professionals and planners for better evacuation policy making and route planning.

Topics: Sensors , Actuators , Modeling
Commentary by Dr. Valentin Fuster
2013;():V004T08A012. doi:10.1115/DETC2013-12882.

In the past few years, the Computer-Aided Technologies, also known as Computer-Aided X (CAX) have been evolving to the Cloud. Cloud computing provides remote services with data storage, software, platform and infrastructure. The next-generation computing applications rely on the collaborations using the technologies of Cloud-Aided Technologies, or Cloud-Aided X (CLAX). The engineers and designers at various locations in different time zones can collaboratively and simultaneously work on a computing design project using CLAX. Issues such as security, conflict, storage, and online computing are inevitable. This paper presents the challenging problems in cloud-based collaborations and some principles for CLAX.

Topics: Collaboration
Commentary by Dr. Valentin Fuster
2013;():V004T08A013. doi:10.1115/DETC2013-12920.

Wireless sensor networks (WSNs) are limited to resources including computing power, storage capacity, and especially energy supply. Thus, energy consumption of sensor nodes has become a dominant performance index for a WSN. In addition, data transmission between sensor nodes is a main energy consumer of WSNs. This paper presents a method called immune genetic algorithm based multiple-mobile-agent itinerary planning (IGA-M2IP) that addresses issues of energy consumption in large-scale WSNs. The IGA-M2IP preserves a GA’s advantages, and further improves a GA’s efficiency by restraining possible degenerative phenomena during the evolutionary process.

Commentary by Dr. Valentin Fuster
2013;():V004T08A014. doi:10.1115/DETC2013-13543.

This paper presents a simulation environment to control modular robots in a program which is directly applicable for hardware control. Computer simulations provide a powerful tool for visualizing robotic systems as evidenced by myriad environments developed for prototyping, designing, and testing robots. In the presented simulation environment, code written for hardware control can be validated within the simulation with a minor modification due to the close integration of the hardware and simulation control software. The simulation environment is built atop Ch, the C/C++ interpreter which provides the capability to remotely control robots through code, Open Dynamics Engine, which accurately models the dynamics of the bodies, and OpenScene-Graph, used to provide 3D visualization. Multiple experiments were run which proved the accuracy of the simulation by comparing results with the hardware control code in both single- and multi-robot situations.

Commentary by Dr. Valentin Fuster

2013 ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Fractional Derivatives and Their Applications

2013;():V004T08A015. doi:10.1115/DETC2013-12059.

Finite difference methods for fractional differential equation are ever proposed. However, precise error orders have not been analyzed for the methods higher than first order accuracy. This paper proposes a few finite difference methods for fractional diffusion equations and shows our methods have second order accuracy under the conditions that the solution functions have higher order than second order at boundaries. In addition, we show that the accuracy may decrease in the case that the solution functions have lower order than second order at boundaries when we use second order accuracy scheme. In this paper, we treat schemes based on Grunwald-Letnikov definition and apply them to three kinds of fractional diffusion equations using Riemann-Liouville derivative operator including time-fractional diffusion equation, space-fractional diffusion equation and time-space-fractional diffusion equation. Finally, we show the simulation results which indicate that our methods are stable and have successfully second order accuracy under the assumed conditions.

Commentary by Dr. Valentin Fuster
2013;():V004T08A016. doi:10.1115/DETC2013-12332.

In this manuscript, we investigated the Euler-Lagrange equations on Cantor sets within the local fractional operators. To illustrate the proposed method two examples are presented.

Commentary by Dr. Valentin Fuster
2013;():V004T08A017. doi:10.1115/DETC2013-12388.

This paper presents a numerical scheme for a class of Isoperimetric Constraint Variational Problems (ICVPs) defined in terms of an A-operator introduced recently. In this scheme, Bernstein’s polynomials are used to approximate the desired function and to reduce the problem from a functional space to an eigenvalue problem in a finite dimensional space. Properties of the eigenvalues and eigenvectors of this problem are used to obtain approximate solutions to the problem. Results for two examples are presented to demonstrate the effectiveness of the proposed scheme. In special cases the A-operator reduce to Riemann-Liouville, Caputo, Riesz-Riemann-Liouville and Riesz-Caputo, and several other fractional derivatives defined in the literature. Thus, the approach presented here provides a general scheme for ICVPs defined using different types of fractional derivatives. Although, only Bernstein’s polynomials are used here to approximate the solutions, many other approximation schemes are possible. Effectiveness of these approximation schemes will be presented in the future.

Commentary by Dr. Valentin Fuster
2013;():V004T08A018. doi:10.1115/DETC2013-12470.

The root locus (RL) is a classical tool for the stability analysis of integer order linear systems, but its application in the fractional counterpart poses some difficulties. Therefore, researchers have mainly preferred to adopt frequency based methods. Nevertheless, recently the RL was considered for the stability analysis of fractional systems. One first method is by tacking advantage of commensurable expressions that occur when truncating fractional orders up to a finite precision. The second method consists of searching the complex plane for solutions of the characteristic equation using a numerical procedure. The resulting charts are insightful about the characteristics of the closed-loop system that outperform the frequency response methods. Given the limited know how in this particular topic and the shortage of literature, this study explores several types of fractional-order transfer functions and presents the corresponding RL.

Commentary by Dr. Valentin Fuster
2013;():V004T08A019. doi:10.1115/DETC2013-12604.

In this paper we study space- and time-fractional diffusion equations called Fractional Legendre-Pearson Diffusion Equations (FLPDEs) in finite space interval. We define the space fractional part using Fractional Legendre Operators and the time fractional part using Fractional Caputo derivative. We consider both the standard and symmetrized versions of FLPDEs. For both equations, we use the method of integral Legendre transform and inverse integral Legendre transform to solve the two equations. The solutions are given in the form of infinite series containing Legendre polynomials dependent on the space variable and Mittag-Leffler functions dependent on time. We demonstrate that these series are convergent. The simplicity with which the solutions of the FLPDEs are obtained in closed form should initiate further research in this field.

Commentary by Dr. Valentin Fuster
2013;():V004T08A020. doi:10.1115/DETC2013-12705.

Harmonic oscillators play a fundamental role in many areas of science and engineering, such as classical mechanics, electronics, quantum physics, and others. As a result, harmonic oscillators have been studied extensively. Classical harmonic oscillators are defined using integer order derivatives. In recent years, fractional derivatives have been used to model the behaviors of damped systems more accurately. In this paper, we use three operators called K-, A- and B-operators to define the equation of motion of an oscillator. In contrast to fractional integral and derivative operators which use fractional power kernels or their variations in their definitions, the K-, A- and B-operators allow the kernel to be arbitrary. In the case when the kernel is a power kernel, these operators reduce to fractional integral and derivative operators. Thus, they are more general than the fractional integral and derivative operators. Because of the general nature of the K-, A- and B-operators, the harmonic oscillators are called the generalized harmonic oscillators. The equations of motion of a generalized harmonic oscillator are obtained using a generalized Euler-Lagrange equation presented recently. In general, the resulting equations cannot be solved in closed form. A numerical scheme is presented to solve these equations. To verify the effectiveness of the numerical scheme, a problem is considered for which a closed form solution could be found. Numerical solution for the problem is compared with the analytical solution. It is demonstrated that the numerical scheme is convergent, and the order of convergence is 2. For a special kernel, this scheme reduces to a scheme presented recently in the literature.

Commentary by Dr. Valentin Fuster
2013;():V004T08A021. doi:10.1115/DETC2013-12724.

In this paper, a novel fractional order (FO) reaching law with an FO sign function is proposed. It is used to guarantee the the occurrence of reaching phase in finite time. Since the traditional integer order (IO) reaching law can be considered as a special case of the FO reaching law, it is more likely for the FO reaching law to obtain better performance. The properties of the FO sign function are used to prove the capability of states to approach the switching manifolds. Compared with the IO sign function in the classical reaching law, the states reach the switching manifolds faster with the FO reaching law. It will be shown that the reaching time under the FO SMC can be reduced by analyzing the FO sign function under appropriate conditions. Moreover, the sliding dynamics can arrive at the equilibrium point more rapidly by applying the FO reaching law. Simulation results including comparisons between the FO SMC and the IO SMC are presented to illustrate the advantages of the proposed scheme. Finally, a fractional horsepower dynamometer is utilized as a real time simulation platform to demonstrate the effectiveness of the proposed FO reaching law.

Commentary by Dr. Valentin Fuster
2013;():V004T08A022. doi:10.1115/DETC2013-12734.

What is the most efficient search strategy for the random located target sites subject to the physical and biological constraints? Previous results suggested the Levy flight is the best option to characterize this optimal problem, however, which ignores the understanding and learning abilities of the searcher agents. In the paper we propose the Continuous Time Random Walk (C-TRW) optimal search framework and find the optimum for both of search length’s and waiting time’s distributions. Based on fractional calculus technique, we further derive its master equation to show the mechanism of such complex fractional dynamics. Numerous simulations are provided to illustrate the non-destructive and destructive cases.

Commentary by Dr. Valentin Fuster
2013;():V004T08A023. doi:10.1115/DETC2013-12749.

A new fractional order adaptive scheme is proposed for the Coulomb friction compensation in a servo control system. This adaptive compensator is designed such that it can estimate the unknown Coulomb friction coefficient; therefore, the zero convergence of the error system will be guaranteed. The design procedure of the proposed control scheme is very simple and its application is easy. Also, the friction in the servo control system is compensated by a good tracking performance. The comparison shows that the fractional order compensator has less tracking error and better response. A fractional horsepower dynamometer was developed as a general purpose hardware-in-the-loop real-time simulation platform to emulate Coulomb friction as a mechanical nonlinearity. The simulation and experimental results demonstrate that the proposed controller has a satisfactory performance and diminishes friction characteristics.

Commentary by Dr. Valentin Fuster
2013;():V004T08A024. doi:10.1115/DETC2013-12793.

This paper presents a fractional order extremum seeking control scheme for grid-connected photovoltaic (PV) systems tasks to better accommodate rapid varying solar irradiance for photovoltaic (PV) arrays. The stability analysis of the proposed control algorithm is presented first. Then the new algorithm is benchmarked against the integer order extremum seeking control. Our extensive simulation and experimental results show that, our proposed maximum power point tracker has faster convergence speed in comparison to integer order and incremental conductance algorithm and also less total harmonic distortion (THD) in the injected current to the grid.

Commentary by Dr. Valentin Fuster
2013;():V004T08A025. doi:10.1115/DETC2013-12824.

This paper addresses the stability of linear commensurate order fractional systems, Dn (X) = AX 0 < n < 1, using the infinite state approach. First, the energy of a fractional integrator is defined, using the distributed energy of its initial state. Compared to the integer order case, this energy is characterized by a long memory decay, which is the characteristic feature of fractional systems. Then, it is applied to define the energy V(t) of a one derivative system. Numerical simulations exhibit the influence of initial conditions on V(t). Thanks to the definition of a dissipation function, a stability condition is derived. Finally, the general case is investigated and a weighted Lyapunov function is derived, using a positive P matrix, related to the eigenvalues of A matrix.

Topics: Stability
Commentary by Dr. Valentin Fuster
2013;():V004T08A026. doi:10.1115/DETC2013-12830.

This paper, composed of two parts, addresses the stability of linear commensurate order fractional systems, Dn (X) = A X 0 < n < 1, using the infinite state approach. Whereas Part 1 has been dedicated to the definition of fractional systems energy, Part 2 deals with the derivation of a stability condition. When the eigenvalues of A are real, the modal representation shows that system energy is the sum of independent modal energies, so the derivation of a stability condition is straightforward in this case. On the contrary, when the eigenvalues are complex with positive real parts, unusual energy dynamics depending on initial conditions prevent direct derivation of a stability condition. Thus, an indirect method is proposed to formulate a stability condition in the complex eigenvalues case.

Topics: Stability
Commentary by Dr. Valentin Fuster
2013;():V004T08A027. doi:10.1115/DETC2013-12835.

Fractional difference equations, or fractional maps, appear at least in two ways. One way is that some of them directly come from the discrete dynamical process with memory or heredity. Another one is that some of them are originated from the discretization of the continuous fractional differential equations. Such maps may be not chaotic. On the other hand, anti-control of chaos (or chaotification for brevity) has potential applications in secure communication. In this paper, we make non-chaotic fractional maps chaotic by constructing suitable controllers. The presented control technique and method has been applied to the non-chaotic fractional Tent map, Hénon map, and Lozi map, which become chaotic via the designed controllers. The computer graphics are also displayed to show the efficiency of the designed controllers.

Topics: Chaos
Commentary by Dr. Valentin Fuster
2013;():V004T08A028. doi:10.1115/DETC2013-13227.

Fractional calculus techniques (non-integer order systems) have been successfully applied in many fields of electronics and engineering. In this paper the effects of including fractional order electronic components on the radiated antenna pattern of a circular loop antenna is presented. A fractional order “RLC” impedance matching circuit is placed between the generator and the equivalent circuit of a loop antenna. The input impedance of the antenna and the antenna gain are controllable through varying the fractional orders of an inductive element and a capacitive element (Fractors) in the matching network. The circuit is presented and solved analytically, and some numerical simulations follow. We discuss the effects of fractional order components on the resulting radiation patterns. In particular, the amplitude of the antenna gain is controlled by the fractional order parameters. This effect could be exploited in future for antenna beam-forming applications when using an array of antenna elements. Further, the input impedance of the antenna circuit can also be controlled by the fractional order components. The introduction of fractional order variables provides for higher degrees of freedom, enabling a flexible approach to tuning antennas for optimal performance.

Commentary by Dr. Valentin Fuster
2013;():V004T08A029. doi:10.1115/DETC2013-13247.

This paper considers the energy aspects of fractional elements defined by the equation Display FormulaFt=kλDtλ0xt. In contrast to the typically conservative assumption of classical physics that lead to the potential and kinetic energy expressions, a number of important non-conservative differences are exposed. Firstly, the considerations must be time-based rather than displacement or momentum based variables. Time based equations for energy behavior of fractional elements are presented and example applications are considered. The effect of fractional order on the energy requirements and energy return of these systems is shown. Importantly, it is shown that the history, or initialization, has a strong effect on energy requirements. Finally, compact expressions for the work or energy, are developed.

Commentary by Dr. Valentin Fuster
2013;():V004T08A030. doi:10.1115/DETC2013-13442.

In this research, we developed a position control system for a hybrid actuator using position, velocity and pressure feedback loops as well as a force-blending algorithm. The actuator uses combination of a spherical MR-brake and three air muscles to create motion in two degrees-of-freedom (DOF). The spherical MR-brake is capable of rotating along three axes and restricts all motion when engaged. The control system helps prevent overshoot and instability in the air muscles by engaging the MR-brake when necessary. It also provides significant improvement in response time by making high-gain PID control of air muscles possible. Such an actuation scheme can be used in a wide-variety of advanced robotics applications such as walking robots, bio-robotics and exoskeletons, where high power, multi-DOF actuation is required in a compact volume.

Commentary by Dr. Valentin Fuster
2013;():V004T08A031. doi:10.1115/DETC2013-13444.

A robust sliding mode control (SMC) technique is introduced in this paper for a class of fractional order (FO) nonlinear dynamical systems. Using the sliding mode control technique, a sliding surface is determined and the control law is established. A new LMI criterion based on the sliding mode control law is derived to make the states of the FO nonlinear system asymptotically gravitate toward the origin which can work for any order of the system, 0<q<2. The designed control scheme can also control the uncertain FO nonlinear systems, i.e. the controller is robust against the system uncertainty and guarantees the property of asymptotical stability. The advantage of the method is that the control scheme does not depend on the order of systems model and it is fairly simple. So, there is no complexity in the application of our proposed method. An illustrative simulation result is given to demonstrate the effectiveness of the proposed robust sliding mode control design.

Commentary by Dr. Valentin Fuster
2013;():V004T08A032. doi:10.1115/DETC2013-13498.

In this paper, fractional-order electrical elements are considered as energy storage devices. They are studied by comparing the energy available from the element to do future external work, relative to the energy input into the element in the past. A standard circuit realization is used to represent the fractional-order element connected to an inductor with a given initial current. This circuit realization is used to determine the energy returned by both capacitive and inductive fractional-order elements of order between zero and one. Plots of the energy stored versus time are provided. The major conclusion is that fractional-order elements tend to rapidly dissipate much of their input energy leaving less energy for doing work in the future.

Commentary by Dr. Valentin Fuster
2013;():V004T08A033. doi:10.1115/DETC2013-13653.

A new method of controlling and optimizing robotic gaits for a modular robotic system is presented in this paper. A robotic gait is implemented on a robotic system consisting of three Mobot modules for a total of twelve degrees of freedom using a Fourier series representation for the periodic motion of each joint. The gait implementation allows robotic modules to perform synchronized gaits with little or no communication with each other making it scalable to increasing numbers of modules. The coefficients of the Fourier series are optimized by a genetic algorithm to find gaits which move the robot cluster quickly and efficiently across flat terrain. Simulated and experimental results show that the optimized gaits can have over twice as much speed as randomly generated gaits.

Commentary by Dr. Valentin Fuster

2013 ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Mechatronic and Embedded Energy Systems

2013;():V004T08A034. doi:10.1115/DETC2013-12310.

Advanced technical developments have increased the efficiency of devices in capturing trace amounts of energy from the environment (such as from human movements) and transforming them into electrical energy (e.g., to instantly charge mobile devices). In addition, advancements in microprocessor technology have increased power efficiency, effectively reducing power consumption requirements.

In combination, these developments have sparked interest in the engineering community to develop more and more applications that utilize energy harvesting for power. The approach here described aims to designing and manufacturing an innovative easy-to-use and general-purpose device for energy harvesting in general purpose shoes. The novelty of this device is the integration of polymer and ceramic piezomaterials accomplished by injection molding. In this spirit, this paper examines different devices that can be built into a shoe, (where excess energy is readily harvested) and used for generating electrical power while walking. A Main purpose is the development of an indoor localization system embedded in shoes that periodically broadcasts a digital RFID as the bearer walks. Results are encouraging and real life test are conducted on the first series of prototypes.

Commentary by Dr. Valentin Fuster
2013;():V004T08A035. doi:10.1115/DETC2013-12726.

Energy is one of the most important foundations of the world. However, the demand for lighting consumes a significant amount of electricity. In order to save lighting electricity and reduce cost, one obvious way is to supplement artificial light with natural light. The mixing of artificial and natural lighting, known as hybrid lighting, can be used to indoors for all lighting needs. In order to maintain the overall illumination level at the rated value, the amount of artificial light needs to change according to the varying natural light. To meet the desired energy saving potential, a suitable means for minimizing energy usage throughout the day must be developed. Minimum energy point tracking (MEPT) algorithms can be utilized to tackle this minimization problem. In this paper, a minimum energy cognitive lighting control prototype is proposed, designed and developed. A simple PID control law is implemented to maintain an arbitrary level of illumination while a sliding mode based extremum seeking controller (SM-ESC) is employed to minimize energy usage in the lights. Furthermore, this paper presents the experiment results of our MEPT research and tracking control for light level. The experimental results can show the practicality and effectiveness of the proposed minimum cognitive energy lighting control scheme.

Commentary by Dr. Valentin Fuster
2013;():V004T08A036. doi:10.1115/DETC2013-12735.

Control theory, once described as the “Physics of the 21st Century,” is pervading to almost all subjects of higher learning. However, it is a difficult topic for many students, especially when introduced at the undergraduate lower level. Providing hands-on experience is often a great aid for teaching difficult concepts, but for control theory forcing a hands-on component can distract from the learning if the students are unprepared. An effective control theory laboratory curriculum builds on the foundations of statics and dynamics, circuit theory, signal processing and programming course-work. However, undergraduate students have a limited educational experience and are typically lacking in one or more of those foundations. Coupled with the unfamiliarity of the common equipment found in teaching labs, students often find themselves overwhelmed and struggle with the setups, limiting their exposure to the topic of control theory. Some industry and education companies have introduced extensive control workstations to bring integrated control theory to a teaching laboratory; however these systems are expensive and specialized, limiting their reach and effectiveness. In this paper, a low-cost mechatronics control theory personal laboratory setup with a proposed curriculum is developed for undergraduate students that addresses their uncertain foundation and improves accessibility by introducing portability to maximize the learning outcomes.

Topics: Mechatronics
Commentary by Dr. Valentin Fuster
2013;():V004T08A037. doi:10.1115/DETC2013-12770.

A mechanical motion rectifier (MMR) based energy harvester is designed to harness the vibrational power from railroad track deflections due to passing trains. Whereas typical existing vibration energy harvester technologies are built for low power applications of milliwatts range, the proposed harvester will be designed for higher power applications such as major track-side equipment. This includes warning signals, switches, and health monitoring systems, which typically require a power supply of 10–100 Watts. To achieve this goal we implement the MMR, a newly patented motion conversion mechanism which efficiently transforms irregular pulse-like bidirectional linear vibration into regulated unidirectional rotational motion. The single-shaft MMR design improves previously developed motion conversion technologies, increasing energy harvester efficiency and power harvesting potential. Features of the MMR include bidirectional to unidirectional motion conversion and flywheel speed regulation. Its advantages include improved reliability, efficiency, and steadier output power. Harvester prototype testing results illustrate features and benefits of the MMR based harvester, showing reduction of continual system loading, regulation of generator speed, and capability for continuous DC power generation.

Commentary by Dr. Valentin Fuster
2013;():V004T08A038. doi:10.1115/DETC2013-13240.

Hybrid Electric Vehicle (HEV) and pure Electric Vehicle (EV) are potential technologies to reduce fuel consumption and emissions in transportation sector. To educate next generation of automotive engineers with strong background in hybrid/electric drive vehicles, Michigan Technological University and partnering institutions General Motors, AVL, Argonne National Laboratory, Woodward, and MathWorks, have built an HEV/EV interdisciplinary program to develop curriculum for the education and outreach in transportation electrification.

Model-based design is emerging as an effective method to solve complicated control problems in automotive and aerospace industries. This paper presents the development of model-based embedded control course curriculum, one of the courses of Michigan Tech HEV/EV interdisciplinary program, to prepare students for their future career in automotive controls. The course goals, the development of teaching materials and associated laboratories, and the design of final project, are discussed. The developed course has been offered in Spring semesters since 2011 and received very positive feedback from students both in Mechanical Engineering – Engineering Mechanics (MEEM) and Electrical and Computer Engineering (ECE) Departments at Michigan Tech.

Commentary by Dr. Valentin Fuster

2013 ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Mechatronic Control and Electrical Vehicular Systems

2013;():V004T08A039. doi:10.1115/DETC2013-12062.

Scalability tests are a common method to verify the adaptability of software components. When developing embedded systems, these tests could be put into practice by increasing the number of computing cores, as well as by changing the underlying processor architecture, for example. Therefore, it is common practice to utilize reconfigurable virtual platforms for embedded software scalability tests and design space exploration. Nevertheless, setting up proper test cases, consisting of distinct virtual platform configurations, toolchains, linker scripts and startup codes requires in-depth knowledge in hardware development. Therefore, in order to offer software engineers the possibility to create and operate a variety of possible virtual heterogeneous embedded multi core platforms for testing purposes on their own, this paper introduces a tool set for creating virtual platforms including appropriate toolchains and build environments from a software engineer’s point of view. The feasibility of our tool set was evaluated in a user-centered case study. Hence, a group of software engineers are asked to perform certain tasks in the field of embedded multi core programming.

Commentary by Dr. Valentin Fuster
2013;():V004T08A040. doi:10.1115/DETC2013-12785.

This paper investigates the impact of driver’s behavior on the fuel efficiency of a hybrid electric vehicle (HEV) and its powertrain components, including engine, motor, and battery. The simulation study focuses on the investigation of power request, power output, energy loss, and operating region of powertrain components with the change of driver’s behavior. It is well known that a noticeable difference between the sticker number fuel economy and actual fuel economy will happen when a driver drives aggressively. To simulate aggressive driving, the input driving cycles are scaled from the baseline driving cycles to increase the level of acceleration/deceleration. With scaled aggressive driving cycles, the simulation result shows a significant change of HEV equivalent fuel economy. In addition, the high power demands of aggressive driving cause engine to operate within a higher fuel rate region. Furthermore, the engine is started and shut down frequently due to the large instantaneous power request peaks, which result in high energy loss. The simulation study of the impact of aggressive driving on the HEV fuel efficiency is conducted for a power-split hybrid electric vehicle using powertrain simulation and analysis software Autonomie developed by Argonne National Laboratory. The performance of the major powertrain components is analyzed when the HEV operates at different level of aggressiveness. The simulation results provide useful information to identify the major factors that need to be included in the vehicle control design to improve the fuel efficiency of HEVs under aggressive driving.

Commentary by Dr. Valentin Fuster
2013;():V004T08A041. doi:10.1115/DETC2013-12888.

The FlexRay bus protocol recently adopted by the automotive industry provides both a time- and event-triggered communication paradigm, combined with communication via two independent channels, as well as optional bus-guardians in order to meet the bandwidth and reliability requirements by present and future emerging automotive applications.

Despite the benefits and improvements, when compared to traditional bus systems (e.g., CAN), rare faults may still occur. In this regard, this paper presents an experimental investigation of the clique problem, where a FlexRay network gets partitioned into multiple functional domains. In such a scenario the nodes within a domain may still be able to communicate with each other, however, not across domain boundaries. As a result affected applications that rely on information from nodes of either domain may be impaired in their intended functionality as long as such a clique exists. Such an impairment affecting critical applications like the braking system may result in hazardous situations.

Commentary by Dr. Valentin Fuster
2013;():V004T08A042. doi:10.1115/DETC2013-13052.

Multidisciplinary systems, such as mechatronic systems, are particularly complex to design because the designer needs knowledge in many fields. This paper is part of a routine process design to optimize the topology of a multidisciplinary system, which is difficult when dealing with more than one discipline or when solutions must be chosen within a set of components and combined. To solve this problem, an approach for the design and optimization of such systems is proposed. It is based on topology optimization, which combines the parametric optimization, using tools like genetic algorithms or particle swarm optimization, and the Case-Based Reasoning to find the best possible solutions by combining and adapting cases within a database or a set of components. This approach is then applied to the design of a gripping tool which will be mounted as a robot effector. This system belongs to the family of mechatronic systems which integrates mechanical, electrical, control and software engineering.

Topics: Design , Optimization
Commentary by Dr. Valentin Fuster
2013;():V004T08A043. doi:10.1115/DETC2013-13503.

Roll-to-Roll systems handling web material such as papers, polymers, textiles or metals are very common in the industry. One of the main objectives in web handling plant is to reach an expected web speed while maintaining the web tension within an acceptable range around the tension reference in the entire processing line. In the recent years, several works have focused on the topic of web tension control using H approaches. In the traditional way, each motor driven roller is controlled in speed and the web tension control is ensured by an external loop. This paper proposes to compare, for the first time, the traditional control strategy with a control strategy including position control rather than speed control. In fact, position control is commonly used in printing industry. The comparison will be ensured in frequency and time domain and take into account the reference tracking performances and the robustness to web elasticity variations.

Commentary by Dr. Valentin Fuster

2013 ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Mechatronics and Embedded Systems Applications

2013;():V004T08A044. doi:10.1115/DETC2013-12118.

This paper proposes a hybridization design and analysis of an air/electric power system in order to extend the service life of the batteries. During the analysis process, the dynamic model of air motor, electric motor and hybrid power mode will be constructed and used in the FPGA speed controller design. By the modular methodology of FPGA, the hybrid power system can successfully operate under ECE-40 driving cycle with PI speed controller. The testing results indicate that the total air consumption is about 256 liters under air motor mode and the electric energy consumption is about 530 coulombs under DC servo motor mode. However, in a hybrid mode, the current reduction of the battery is about 18.5%, and then the service life of the battery can be improved. In addition, the experimental data shows that the chattering ranges of the air motor and the electric motor are within ±1 km/h and ±0.2 km/h respectively under ECE-40 driving cycle testing.

Topics: Design
Commentary by Dr. Valentin Fuster
2013;():V004T08A045. doi:10.1115/DETC2013-12317.

This paper aims to propose an innovative idea of an embedded intelligent, multimedia and interactive shop system where embedded vision systems can analyse human behaviours around shelves for interactivity and statistical purposes, mostly devoted to customer behaviour analysis, planogram maintenance and out of stock detection. We discuss the need for new services into the shop, involving consumers more directly and instigating them to increase their satisfaction and, as a consequence, their purchases. To do this, technology is very important and allows making interactions between costumers and products and between customers and the environment of the shop a rich source of marketing analysis. In particular we focus on concepts of monitoring and interactivity, introducing several emerging technologies in the field of retail environments. The main novelty of the paper is the general architecture of the system together with the introduction of a series of intelligent embedded systems, yet implemented and tested in a dataset recorded during the EuroShop trade fair, in cooperation with Grottini group, a leading company in Retail Design industry based in Italy. Results are convincing and most of all the general architecture is affordable in this specific application.

Commentary by Dr. Valentin Fuster
2013;():V004T08A046. doi:10.1115/DETC2013-12530.

This paper discusses the basic considerations and development of a prototype demo system for the wireless charging of supercapacitor electric vehicles, which uses magnetic resonance coupling. Considering future ubiquitous wireless vehicle stationary and dynamic charging facilities, supercapacitor could be an ideal device to store a reasonable amount of electrical energy for a relatively short period of time. The prototype system includes all the major functional components for an electric vehicle’s powertrain and wireless charging system including coils for energy emitting and receiving, a FPGA PWM input generation board, high frequency DC/AC inverter and AC/DC rectifier circuits, an on-board supercapacitor module, sensors for SOC level measurement and charging position detection, etc. All the components are integrated into a model electric vehicle. The prototype system well demonstrates the idea of the fast and frequent wireless charging of on-board supercapacitors. Promising results from initial experiments are explained; while further investigations, optimized design of components and a system-level optimization are needed.

Commentary by Dr. Valentin Fuster
2013;():V004T08A047. doi:10.1115/DETC2013-13343.

Resistance welding is an alternative process to mechanical fastening and adhesive bonding in joining thermoplastic composites. The resistance welding procedure involves the Joule heating of a heating element located between two adjoining thermoplastics. The application of heat causes the material in the interface between two surfaces to melt. The current stops then and the interfacing surfaces bound under a compaction pressure, while cooling. This results in a fusion bond between the two components. A fuzzy logic controller is designed and implemented in real-time using the temperature estimate as the feedback signal. The result is a controller capable of maintaining the weld temperature within 10% of the reference temperature.

Commentary by Dr. Valentin Fuster
2013;():V004T08A048. doi:10.1115/DETC2013-13450.

Many embedded systems applications have hard timing requirements where real-time processes with precedence and exclusion relations must be completed before specified deadlines. This requires that the worst-case computation times of the real-time processes be estimated with sufficient precision during system design, which sometimes can be difficult in practice. If the actual computation time of a real-time process during run-time exceeds the estimated worst-case computation time, an overrun will occur, which may cause the real-time process to not only miss its own deadline, but also cause a cascade of other real-time processes to also miss their deadline, possibly resulting in total system failure. However, if the actual computation time of a real-time process during run-time is less than the estimated worst-case computation time, an underrun will occur, which may result in under-utilization of system resources. This paper describes a method for handling underruns and overruns when scheduling a set of real-time processes with precedence and exclusion relations using a pre-run-time schedule. The technique effectively tracks and utilizes unused processor time resources to reduce the chances of missing real-time process deadlines, thereby providing the capability to significantly increase both system utilization and system robustness in the presence of inaccurate estimates of the worst-case computation times of real-time processes.

Commentary by Dr. Valentin Fuster

2013 ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Sensors and Actuators

2013;():V004T08A049. doi:10.1115/DETC2013-12378.

Sensors are an integral part of many engineered products and systems. Biological inspiration has the potential to improve current sensor designs as well as inspire innovative ones. Mimicking nature offers more than just the observable aspects that conjure up engineering solutions performing similar functions, but also less obvious strategic and sustainable aspects. This paper presents the design of an innovative, biologically-inspired chemical sensor that performs “up-front” processing through mechanical filtering. Functional representation and abstraction were used to place the biological system information in an engineering context, and facilitate the bioinspired design process. Inspiration from the physiology (function) of the guard cell coupled with the morphology (form) and physiology of tropomyosin resulted in multiple concept variants for the chemical sensor. The chemical sensor conceptual designs are provided along with detailed descriptions. Applications of the sensor design include environmental monitoring of harmful gases, and a non-invasive approach to detect illnesses including diabetes, liver disease, and cancer on the breath.

Topics: Sensors , Design
Commentary by Dr. Valentin Fuster
2013;():V004T08A050. doi:10.1115/DETC2013-12409.

In haptics applications, fast, stable and crisp force responses are desired. Magnetorheological (MR) brakes are used as actuators in haptics since they provide high torque-to-volume ratios. However, they still tend to be rather large and use high current inputs. We developed a new MR-brake with a T-rotor and serpentine flux path. The new device has 45 mm diameter and 65 mm length. It produces 6.5 Nm torque with 1A current input. It has more than double the torque-to-volume ratio of a commercial MR-brake and a previous T-rotor brake in literature. As such, it can open up many new application areas including portable systems. A prototype was built and tested to assess its effectiveness as a 1 degree-of-freedom (DOF) haptic device in virtual wall collision. The new MR-brake provided a crisp collision and release with the virtual wall.

Topics: Rotors , Brakes
Commentary by Dr. Valentin Fuster
2013;():V004T08A051. doi:10.1115/DETC2013-12906.

In the field of robotics, the most essential requirement for successful navigation is an accurate and numerically inexpensive method for self-localization. This paper presents a method that exploits the principles of directional cosines to setup a rotation matrix to deal with a closed loop PI feedback based model. The system uses a 9 degree of freedom (9DOF) sensor and exploits the benefits of the accuracy of a 3-axis gyroscope by leveraging the measurement of a 3-axis accelerometer and 3-axis magnetometer, which compensates and corrects the accumulative drift generated by integrating the gyroscope velocity measurements. The results show that the method is relatively accurate with a small level of error when compared to vision based glyph recognition and tracking methods for self-localization and is a sustainable method for removing accumulative drift.

Topics: Sensors
Commentary by Dr. Valentin Fuster
2013;():V004T08A052. doi:10.1115/DETC2013-13112.

In many mechanical applications, measuring accelerations along three orthogonal directions is very important. Especially in railway application a rugged, easy-to-configure and low-noise device could be useful to measure the dynamics of the train. Moreover, freight or passenger trains behave very differently and for homologation purposes accelerometers have to be placed both on the axel-boxes, on the bogies and on the carbody. Therefore, accelerometers with different scales along X,Y and Z axes are required. The present paper presents the design, calibration and test on a freight train of new low cost MEMS accelerometers having sensibility that can be interactively adjusted between ±2g, ±16g and ±40g independently over the three axes. The output of these accelerometers can be set either to digital or to analog (with compensation of the cable length). In the paper the design of the nodes both from the electronic and mechanical points of view is presented. The results of the calibration and of the experimentation are also shown.

Commentary by Dr. Valentin Fuster
2013;():V004T08A053. doi:10.1115/DETC2013-13159.

Persons with blindness access computers with the help of refreshable Braille displays and speech synthesis softwares. Braille has distinguished advantages over synthetic speech, especially because of its important role in uplifting education, employment and income. However, commercially available Braille displays are typically priced in the range of 2500–4000 USD (65–100 USD per Braille character) and are thus inaccessible to users in both developed and developing countries. Development of affordable Braille displays is thus a critical need.

Shape Memory Alloy (SMA) based actuation is a potential low-cost alternative to currently employed piezoelectric actuation, and is being used here to develop an affordable Braille display. This paper discusses key challenges identified in SMA based actuation and proposes methods to overcome the same. Prior attempts at developing tactile displays employing SMA based actuation are reviewed and important considerations for the present study are drawn. The configuration and the design of the actuator are thus arrived at. This paper further discusses the performance of fabricated prototypes and the feedback received from limited user trials. It concludes with a discussion on future scope of the work.

Commentary by Dr. Valentin Fuster

2013 ASME/IEEE International Conference on Mechatronic and Embedded Systems and Applications: Small Unmanned Aerial Vehicle Technologies and Applications

2013;():V004T08A054. doi:10.1115/DETC2013-12463.

Due to the importance of the workspace and stability in mobile robot dynamic control, a variety of workspace and stability criteria exist in the field of multi-legged and wheeled robotics. This paper presents a methodology for determining the stable workspace, the subspace of the workspace for which the system is considered stable. The presented derivation utilizes the normal foot force distribution of the system to determine stability and integrates the stability into the lateral workspace of a mobile machining hexapod robot. The analytical inequalities governing the boundary of the stable workspace are derived. A discussion on the effects of physical and geometrical characteristics of the hexapod robot on the stable workspace methodology is given. The stable workspace methodology is validated through a simulation and an application to mobile machining is presented.

Commentary by Dr. Valentin Fuster
2013;():V004T08A055. doi:10.1115/DETC2013-12746.

Though Unmanned Aerial System (UAS) operators have started to push for general acceptance into the National Airspace System (NAS), there remain significant and necessary areas of research. Despite the ‘Unmanned’ moniker, human factors serve a vital role in safe and robust operation. Numerous reports have placed human errors as significant factors in recent UAS incidents, leading many researchers to investigate a framework for analyzing these human factors that lead to incidents. In this paper, the use of Heart Rate Variability (HRV), as an indicator of operator pressure or cognitive load of a UAS operator, is considered. Furthermore, potential applications of HRV research are presented towards applying this new layer of human feedback information to adjust UAS operations to achieve a safer and more resilient UAS. This paper serves as an initial proposal for this bigger closed-loop thinking in UAS human factor research.

Topics: Human factors
Commentary by Dr. Valentin Fuster
2013;():V004T08A056. doi:10.1115/DETC2013-13267.

Studying the biological processes of wildlife and how they react and prevail with human population growth and development has become very important to sustain species and prevent extinction. Wildlife tracking has become a very important tool in this matter by giving researchers an idea of animal territory and habitat. However, the process of finding the animal after it has been tagged can be very tedious and costly. To make this tracking process more efficient, researchers at Utah State University (USU) are developing a low cost RF telemetry system for wildlife tracking using an autonomous Unmanned Aerial Vehicle (UAV) for triangulation and geo-location of the target. The use of small unmanned aircraft systems (UAS) for wildlife tracking offer many advantages such as cost reduction, human effort reduction and data acquisition efficiency due to the usage flexibility offered by the system in comparison to conventional methods. This paper presents the design of this tracking system, and shows some experimental data.

Commentary by Dr. Valentin Fuster
2013;():V004T08A057. doi:10.1115/DETC2013-13466.

Lithium-Polymer (LiPo) batteries are becoming a popular choice for electric small low cost Unmanned Aerial Vehicles (UAVs). In case of a multirotor UAVs, a battery failure means a certain loss of the air frame. To fully utilize their potential and maintain mission safety, a monitoring system predicting battery behaviour is required. In this study a change in battery dynamics during discharge, and its effect of thrust produced by actuators is measured. Experiments simulating flight conditions are performed, and measured data are interpolated with double exponential and polynomial curves. An obvious similarity between the battery state-of-charge and produced thrust is observed. Due to conventional altitude controllers’ inability to cope well with changes in battery dynamics, a controller invariant to those changes is presented.

Commentary by Dr. Valentin Fuster

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