ASME Conference Presenter Attendance Policy and Archival Proceedings

2015;():V003T00A001. doi:10.1115/DETC2015-NS3.

This online compilation of papers from the ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference (IDETC/CIE2015) 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to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.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

17th International Conference on Advanced Vehicle Technologies: Advances in Ground Vehicle Safety and Ergonomics

2015;():V003T01A001. doi:10.1115/DETC2015-46178.

An experimental field study investigating the impact of single wheel hub motor failures on the dynamic behavior of a vehicle and the corresponding driver reaction is presented in this work. The experiment is performed at urban speeds on a closed off test track. The single wheel hub motor failure is emulated with an auxiliary brake system in a modified electric vehicle. Driver reaction times are derived from the measured data and discussed in their experimental context. The failure is rated and evaluated objectively based on the dynamic behavior of the vehicle. Findings indicate that driver reactions are more apparent for the accelerator pedal compared to the steering wheel response. The controllability evaluation of the vehicle behavior shows that no critical traffic situation occurs for the tested failure conditions. However, even small deviations of the vehicle can impair traffic safety, specifically for other traffic participants like bicyclist and pedestrians.

Commentary by Dr. Valentin Fuster
2015;():V003T01A002. doi:10.1115/DETC2015-46507.

This paper presents the use of Finite Element Analysis (FEA) software in recreating a full frontal barrier impact test with a 50th percentile male hybrid III dummy to investigate various passenger vehicle airbag deployment times for the development of an airbag trigger sensor. Results for the physical full frontal barrier impact test where prepared by MGA Research Corporation with a 2007 Toyota Yaris. Using a nonlinear transient dynamic FEA software, a virtual full frontal barrier impact test was created to reproduce the physical results and trends experienced in the physical crash test found in a report by the National Highway Traffic Safety Administration (NHTSA) 5677. The results of the simulation were compared to the results of the physical crash which produced similar trends, but not the same values. The simulation was then used in testing different passenger vehicle airbag deployment times to see its results on specific occupant injury criteria’s; Head Injury Criterion (HIC), Chest Compression Criterion (CC). Four different vehicle speeds where used; 20 km/h, 40 km/h, 56 km/h, and 90 km/h in conjunction with a range of +/− 6 milliseconds in the airbag deployment timing. Results of the airbag deployment timing showed that trends of faster airbag deployment times resulted in lower values for HIC and CC. Following these trends, suggestions for airbag deployment trigger distances were developed to aid in creation of an advanced airbag deployment sensor or crash sensor. While the simulation has yet to be validated, the trends may be assessed and actual values may differ.

Topics: Safety , Airbags
Commentary by Dr. Valentin Fuster
2015;():V003T01A003. doi:10.1115/DETC2015-47135.

Thin-walled tubes subjected to axial crushing have been extensively used as energy absorbers in transportation system. It has been known for some time that inversion of a circular tube can have very high energy absorption capability and a stable reaction force. However, its inversing mechanism is rather unstable, and it requires a lubricated contact surface, both of which largely hinder its wide application. This paper proposes to use corrugated tube for inversion, which provides a stable inversing mechanism and no requirement for lubricated contact. Furthermore to the improvement of inversing stability, a comparison between inversion of corrugated tube and buckling of circular tube has been done. It shows that the inversion of the corrugated tube has longer stroke, higher energy absorption capability and better load uniformity than that of buckling of circular tube.

Topics: Absorption
Commentary by Dr. Valentin Fuster
2015;():V003T01A004. doi:10.1115/DETC2015-47781.

Pedestrians represent one of the most vulnerable road users and comprise nearly 22% of the road crash related fatalities in the world. Therefore, protection of pedestrians in the car-to-pedestrian collisions (CPC) has recently generated increased attention with regulations which involve three subsystem tests for adult pedestrian protection (leg, thigh and head impact tests). The development of a finite element (FE) pedestrian model could be a better alternative that characterizes the whole-body response of vehicle–pedestrian interactions and assesses the pedestrian injuries. The main goal of this study was to develop and to preliminarily validate a FE model corresponding to a 50th male pedestrian in standing posture. The FE model mesh and defined material properties are based on the Global Human Body Modeling (GHBMC) 50th percentile male occupant model. The lower limb-pelvis and lumbar spine regions of the human model were preliminarily validated against the post mortem human surrogate (PMHS) test data recorded in four-point lateral knee bending tests, pelvic impact tests, and lumbar spine bending tests. Then, pedestrian-to-vehicle impact simulations were performed using the whole pedestrian model and the results were compared to corresponding pedestrian PMHS tests. Overall, the preliminary simulation results showed that lower leg response is close to the upper boundaries of PMHS corridors. The pedestrian kinematics predicted by the model was also in the overall range of test data obtained with PMHS with various anthropometries. In addition, the model shows capability to predict the most common injuries observed in pedestrian accidents. Generally, the validated pedestrian model may be used by safety researchers in the design of front ends of new vehicles in order to increase pedestrian protection.

Commentary by Dr. Valentin Fuster
2015;():V003T01A005. doi:10.1115/DETC2015-47936.

This paper presents the map-based navigation of a car with autonomous capabilities using grid-based scan-to-map matching. The autonomous car used for demonstration is built based on Toyota Prius and can control the throttle, the brake and the steering by a computer. The proposed grid-based scan-to-map matching method represents a map with a finite number of grid cells, represents a scan and the map with scan points at each grid as normal distributions (NDs) and constructs a map by matching the scan NDs to the map NDs. The proposed method enables scan-based mapping at high speed while maintaining high accuracy. The representation of a grid cell of a map in terms of multiple NDs further enhances speed and accuracy. The accuracy analysis of the proposed method shows that a small robot with a wheel diameter of 8cm had yielded no loop closure error after the travel of 186m while the terminal position error by the GMapping was approximately 1m with the error growth of 1%. The application of the proposed method with the autonomous car has then demonstrated the ability of the proposed method for autonomous driving with varying and high speed and has also quantified the significance of speed for successful mapping in autonomous driving.

Commentary by Dr. Valentin Fuster
2015;():V003T01A006. doi:10.1115/DETC2015-47939.

The automobile industry has come a long way since the day of invention. The automobile is undergoing the complex and profound changes. The main themes are focused on fuel economy, environment protection, safety, comfort, and intelligentization. From both the status and tendency [1], several main problems of active safety will be presented in this paper, including the cyber physical system, dynamics control and the closed-loop system consisting of driver-vehicle-infrastructure (DVI).

Topics: Safety , Automobiles
Commentary by Dr. Valentin Fuster

17th International Conference on Advanced Vehicle Technologies: Advances in Ground Vehicles Dynamics and Controls

2015;():V003T01A007. doi:10.1115/DETC2015-46228.

This paper discusses a steering rack force estimation scheme using test-rig generated models. In addition to friction identification, a model of the electric power steering system is identified by the use of the instrumented test-rig. It turns out that the friction in the steering system is highly load-dependent, asymmetric with respect to speed, and shows no Stribeck effects. A LuGre model is adopted and fitted to approximate the measured dynamic friction. Consequently, this model is used in a friction compensator which is combined with a linear disturbance observer to estimate the steering rack force. The proposed estimation scheme is analyzed via evaluated system simulations and experiments on the steering system test-rig. Finally, considering the fact that the friction level varies with each steering device manufactured and installed, the paper discusses algorithms for friction level adaptation.

Commentary by Dr. Valentin Fuster
2015;():V003T01A008. doi:10.1115/DETC2015-46766.

Pneumatic tires play a greater role in vibration control of vehicles with stiff or no suspension systems. The challenge is to find an approach that enhances vibratory damping in the tires without increasing the power losses due to rolling resistance effects. This paper presents a novel tire damping enhancement that allows for improved damping within the tire while maintaining the rolling resistance found in a typical pneumatic tire.

The damping enhancement was evaluated by testing an apparatus/demonstrator that simulates a pneumatic tire. The experiment was initially configured to measure the damping ratio of the conventional tire design using a calibrated external excitation and analyzing the decay of the vibration. The damping enhancement presented in the paper was then subjected to the same test and analysis procedure. Results of the analysis show that the proposed damping enhancement measurably decreased the time of the vibratory oscillation.

Topics: Damping , Tires
Commentary by Dr. Valentin Fuster
2015;():V003T01A009. doi:10.1115/DETC2015-46916.

Many energy-harvesting shock absorbers have been proposed in recent years, the most popular design is the electromagnetic harvester including linear electromagnetic shock absorbers, rotational electromagnetic shock absorbers, the mechanical motion rectifier (MMR), and the hydraulic-electromagnetic energy-regenerative shock absorber (HESA). With different energy converting mechanisms, the complicated effects of the inertia and nonlinear damping behaviors will greatly influence the vehicle dynamic performance such as the ride comfort and road handling. In this paper, we will theoretically analyze the dynamics of the suspension system with the HESA and give a guide for the HESA design. Then a simulation model of the HESA is built in AMESim to make comparison studies on the different vehicle dynamics caused by the nonlinear damping behaviors of the HESA. The advantages of HESA in terms of ride comfort and road handling will be evaluated in comparison with the similar design without accumulators and the traditional oil shock absorbers.

Commentary by Dr. Valentin Fuster
2015;():V003T01A010. doi:10.1115/DETC2015-47071.

The suspension design requirements for vehicles that need both good on-road and off-road capabilities as well as vehicles where the payload changes significantly during operation is quite challenging. To overcome the ride comfort vs. handling compromise that most vehicles suffer from some suspension systems offer adjustability and control to overcome this conflict. The uptake of controllable dampers on commercial vehicles, allthough cost effective and technically feasible, have been low mainly because dampers on their own cannot significantly reduce the compromises involved with fully laden vs. empty or on-road vs. off-road use. The University of Pretoria developed a Four State Semi-Active Suspension System (4S4) that allows for the control and adjustability of the stiffness and the damping of the suspension. The 4S4 makes use of solenoid valves of which the response time unfortunately increases with an increase in flow, especially when implemented on larger vehicles, reducing the effectiveness of the control.

This paper presents an alternative to the solenoid valves currently used in the 4S4 in the form of a magneto-Rheological (MR) valve that acts as a normal continuously variable MR damper, but also has the ability to virtually block the flow of fluid, thus switching between the two different spring characteristics. Experimental results show that it is indeed possible to replace the solenoid valves with a MR valve.

Topics: Rheology , Valves
Commentary by Dr. Valentin Fuster
2015;():V003T01A011. doi:10.1115/DETC2015-47180.

The ride comfort of a vehicle is one of the first parameters used to evaluate its performance. Ride comfort has been one of the important research topics since the dawn of the automobile. With the improvement in computational capability, vehicle engineers have modeled vehicles with increasing complexity. Initially vehicles were simplified to quarter car models, where a quarter of the vehicle was modeled with two degrees of freedom (the vertical translation of the sprung and unsprung masses). The “pitch-bounce” model has four degrees of freedom, representing the pitch rotation and vertical translation (bounce) of the vehicle body and chassis and the vertical translation of the front and rear axles and wheels. Finally, with the development of multi-body systems (MBS) software, there is the possibility to model the full vehicle with suspension kinematics and numerous degrees of freedom. The full vehicle model used for this study has 15 unconstrained degrees of freedom and experimentally determined center of mass and inertias. This paper compares the response of a quarter car, pitch-bounce and full vehicle model with the measured response of an actual vehicle.

Topics: Vehicles
Commentary by Dr. Valentin Fuster
2015;():V003T01A012. doi:10.1115/DETC2015-47202.

To improve an automobile’s ride and comfort, handling and stability etc., based on the stiffness test of the air spring, a 15 DOFs vehicle model was created, a strategy of Augment Electronic Stability Program (AESP) with semi-active air suspension integrated was realized. Furthermore, their integrated control strategy combined both the skyhook and groundhook under critical operating conditions was proposed. The property of the vehicle with different control strategies under critical operating conditions of double-line change was simulated in both time and frequency domain, also the phase portrait of the vehicle concerning with the stability was provided, also the Safety Margin of the vehicle introduced in this paper was presented. It’s shown that the trajectory of the automobile is more ideal with AESP, the safety of automobile can be improved, the overall performance of vehicle is optimized as well.

Commentary by Dr. Valentin Fuster
2015;():V003T01A013. doi:10.1115/DETC2015-47322.

The challenge to enhance the vehicle driving and handling with a state estimation and prediction system is presented by fusing a primary real time multibody vehicle model capable of providing a good indication of vehicle stability and control, and a secondary model able to estimate the vehicle state from vehicle real and virtual sensors to correct the indications of the primary model. A mathematical algorithm combines these two models in the drive control system improving the behavior of the active systems of the vehicle.

A Multibody vehicle model has been used to achieve a high fidelity simulation of vehicle dynamics. The selected software is LMS.Virtual.Lab Motion with Real-Time Solver which complements the AMESim Real-Time Solver to handle complex real-time 3D-1D mechatronic systems without any simplified conceptual models.

A Sensor Signal Processing Model has been developed to estimate the vehicle states and calculating tire-road contact forces and vehicle sideslip angle. The methodological approach uses the equations of motion of the chassis applying the fundamental principles of classical physics: Newtonian method and Euler angles.

The control logic is based on the continuous updating of the preview multibody vehicle model by the controller sensors information network, which makes the model forecast behavior closer to the real one and improve comfort and linearity of the vehicle response. The driver inputs (throttle, steer angle and torque, brake, gear) are the same for the MBS real time model and for the real vehicle. A first training logic updates the MBS model based on the real vehicle behavior calculated by the sensor network, where the logic has to update in the MBS model just the factors depending on the vehicle itself (for example car weight, tire temperature, shock absorber damping forces, tires characteristics) and to understand and keep into account different environment variation (wet / dry surface). If the real vehicle is equipped with active control systems to improve handling and stability, as active camber control, drive by wire, ESP, Body movement active controls, the real time multibody model will interact with the models 1D or 3D of these vehicle dynamics controls and will improve their performance with a very high accuracy prediction of their influence on vehicle dynamic response.

In conclusion with the help of the preview multibody vehicle model the drive control logic will increase the performance and drive ability of the vehicle with smart logic interacting with all the active systems.

Commentary by Dr. Valentin Fuster
2015;():V003T01A014. doi:10.1115/DETC2015-47347.

An adaptive searching algorithm for the optimal slip during ABS wheel slip control is proposed. By taking advantage of the fluctuation of wheel slip control, the direction towards the optimal slip can be found, and the target slip calculated by the algorithm asymptotically converged to the optimal slip, which is proved using the Lyapunov theory. A gain-scheduling wheel slip controller is developed to control the wheel slip to the target slip. Simulations on the uniform road and on the road with changed friction are carried out to verify the effectiveness of the proposed algorithm. Simulation results show that the ABS algorithm using the proposed searching algorithm can make full use of the road friction and adapts to road friction changes. Comparing with the conventional rule-based ABS, the pressure modulation amplitude and wheel speed fluctuation is significantly reduced, improving control performance of ABS.

Commentary by Dr. Valentin Fuster
2015;():V003T01A015. doi:10.1115/DETC2015-47463.

A decentralized cooperative driving Non Linear Model Predictive Control (NLMPC) approach for path following and collision avoidance is presented in this paper.

The proposed decentralized approach is based on an information network, which communicates when two or more vehicles are near and so they might collide. In the case in which vehicles are far, online trajectory control is independently computed on-board by means of a NLMPC. When two or more vehicles get closer, trajectory control is no more independently carried out: optimal solution for these vehicles is coupled and thus their trajectories are computed dependently.

Performance of the proposed decentralized NLMPC for cooperative driving was assessed through numerical simulations involving two vehicles. Results were compared with ones of a centralized approach to assess optimality of the solution.

Commentary by Dr. Valentin Fuster
2015;():V003T01A016. doi:10.1115/DETC2015-47614.

Improving the mobility of wheeled robots operating on unstructured terrain is a challenging task that can be approached in different ways. Enhanced mobility results in the vehicle being able to successfully negotiate slopes and obstacles, expanding the range of missions that can be undertaken and reducing the risk of losing or damaging the robot. This goal is directly related to optimizing the way in which traction force is developed at the wheel-terrain contact interfaces. Several strategies to achieve this objective, including traction control algorithms and reconfiguration, have been proposed in the literature. In this work, internal actuation is explored as a means to obtain better mobility on soft and irregular terrain. The use of this technique is demonstrated with a rover prototype in three maneuvers, namely flat soft terrain traverse, slope climbing on soft terrain, and negotiation of a step obstacle. Results show that redundant actuation can be used to improve the behavior of the vehicle, for optimum mobility on soft and irregular terrain.

Commentary by Dr. Valentin Fuster
2015;():V003T01A017. doi:10.1115/DETC2015-47691.

This paper describes a quarter-car braking test rig that includes a hardware-in-the-loop (HIL) means for emulating broader vehicle dynamic effects. The test rig utilizes actual vehicle components such as the suspension-tire assembly and braking system to accurately represent a vehicle during a braking event and a chassis dynamometer’s drum is used to simulate the longitudinal vehicle dynamics. The key problem addressed in this paper is the emulation of sprung mass motion with a commercial electromagnetic linear actuator. By accurately representing the motion, detailed effects such as load transfer that happens in a real braking process can be studied for its effect on the braking performance. The stability of the system with sprung mass emulation under different actuator control modes is analyzed. The successful and stable control scheme found is a cascaded control with a velocity tracking strategy. The workings of the test are illustrated via representative test results that include a locked-wheel braking event and a stop with an anti-lock braking system (ABS).

Topics: Braking
Commentary by Dr. Valentin Fuster

17th International Conference on Advanced Vehicle Technologies: Advances in Light Vehicles Design

2015;():V003T01A018. doi:10.1115/DETC2015-46103.

In this paper the effect of front fork compliance on uncontrolled bicycle stability is analyzed. First the benchmark model of a bicycle is improved to take into account either torsion compliance or bending compliance of front fork, a lumped element approach is adopted introducing additional joints restrained by rotational springs and dampers. Two models having three degrees of freedom are developed and implemented in MATLAB codes to perform stability analysis. Then series of experimental tests are carried out on an advanced carbon fork and a standard steel fork, the modal analysis approach is adopted. Experimental methods and results are presented and discussed. A specific method is developed for identifying the stiffness and damping properties from the bending and torsion modes of the forks. Results obtained with the proposed method agree with data presented in literature. Finally, the identified stiffness and damping parameters are implemented in the simulation codes and some numerical simulations are carried out. Results presented in the paper show a small influence of torsion compliance on stability and a large influence of bending compliance on high speed stability.

Topics: Stability , Bicycles
Commentary by Dr. Valentin Fuster
2015;():V003T01A019. doi:10.1115/DETC2015-46266.

Static and dynamic properties of single-track vehicles components (such as frames, front forks and swing-arms) play a fundamental role from the point of view of vehicle stability, which is a key issue of single-track vehicles dynamics and safety. Nowadays, the stability of a vehicle is studied by means of multi-body codes, in which it is possible to implement models of the tires and of the components of the vehicle. Actually, the chassis and the forks of motorcycles are mechanical systems with distributed mass and stiffness properties, but in most simulation codes the elastic properties of the structural elements are modeled with lumped stiffness and damping elements. Very few research has been carried out on the identification of the lumped elements, of their natural frequencies and damping from laboratory tests.

In the first section of the paper, the concept of modal twist axis is proposed to characterize the dynamic deformability of a structural element. The twist axis is defined as the intersection between the un-deformed plane of the structural element and the plane tangent to the free end of the structural element in deformed condition. If the identification of the twist axis is carried out in resonance condition, the modal twist axis is found. A method for measuring the modal twist axis position and orientation is described. It is based on impulse excitation by means of a modally tuned hammer and three accelerometers which are used for defining the deformed plane.

In the second section of the paper, experimental results obtained on two motorcycle frames are shown. In order to know the modal shapes of the components at the measured natural frequencies, modal analysis is carried out. A correlation between the modal twist axis position and the mode of vibration is shown and discussed. In order to study the influence of the constraints on dynamic properties, the frames are tested in two different constraint conditions: rear constrained and front constrained.

The last section of the paper shows the experimental results obtained by applying the proposed method to other motorcycle components, such as a front fork and a frame with the engine.

Topics: Vehicles
Commentary by Dr. Valentin Fuster
2015;():V003T01A020. doi:10.1115/DETC2015-46639.

This work presents a methodology for the evaluation of energy cost on cycling through on-road tests. The proposed methodology consists on the measurement of the power delivered by the cyclist on the pedals when riding on a real circuit. The aim of the methodology is to generate indexes for the direct evaluation of the effect on energy cost generated by an arbitrary modification implemented on a bike. The modification can include the variation of multiple parameters. The proposed indexes for the evaluation of the energy cost are the mean input power and the mechanical work per distance during the test. The proposed methodology intends to evaluate the energy cost for a given bike-rider set on a given circuit.

A case study is presented for the evaluation of tire pressure influence on energy cost. For the application of the methodology, one cyclist rode on the circuit of interest with a set of different tire pressures. The power delivered by the cyclist was measured on the pedals. Several tests were conducted for each pressure in order to achieve a good level of significance. The results obtained for the case study with the proposed methodology are compared with the results of a method based on rolling resistance coefficients reported in literature.

Topics: Pressure , Roads , Tires
Commentary by Dr. Valentin Fuster
2015;():V003T01A021. doi:10.1115/DETC2015-47319.

Anti-Lock Braking Systems (ABS) have been developed and integrated into vehicles since it is invented more than thirty years ago. However, most of nowadays ABS are designed for multi-wheeled passenger cars, commercial cars and trucks. Due to the technical complexity and additional cost, ABS is not as common on two-wheeled vehicles, such as motorcycle, electric scooter, electric bike, etc. Study shows that injuries and deaths in relation to two-wheeled vehicles with ABS are significantly decreased. This paper is to provide a brief review of the state-of-the-art on the ABS configuration of two-wheeled vehicles.

Commentary by Dr. Valentin Fuster
2015;():V003T01A022. doi:10.1115/DETC2015-47824.

One of the most important parameters evaluated by racing and trekking cyclists is vibrational comfort: as generally accepted, it is closely correlated to the response of bicycle components in combination with the cyclist’s characteristics.

Vibration transmissibility of wheels and saddles was recently studied during lab tests using a wooden dummy bottom resting on the saddle or in road tests on an instrumented racing bicycle at different speeds on different surfaces.

The use of shakers is also well established in the evaluation of cyclist’s posture effects on the overall bicycle behaviour. In fact, in previous works, either a servohydraulic actuator was applied to the seatpost of a bicycle frame hinged at the front wheel axle with a cycling tester, or two electrodynamic shakers were applied under the wheels of a fully equipped bicycle, with a cyclist sitting statically on the saddle. In the present study, the combination of a servohydraulic actuator and a roller type bench allowed to overcome the limitations of the former experiences. Random vibrations were input to the bicycle-cyclist complex by means of rollers supporting the rear wheel while cyclists were cycling unrestrained on the rollers. The test bench setup and tuning approach are presented for comparison with results available from previous bench and road tests.

Topics: Bicycles , Rollers
Commentary by Dr. Valentin Fuster
2015;():V003T01A023. doi:10.1115/DETC2015-48034.

Since product development lead-time needs to be as short as possible in contemporary enterprises, it is necessary to assess and optimize the performance of the structure in conceptual design phase for avoiding the time consuming production of trial models for vehicle body. This paper proposes a conceptual design tool based on optimization algorithms for global body frames named Vehicle Concept Design-Intelligent CAE system (VCD-ICAE). A multilevel optimization algorithm is applied to optimize the body performance, decide the size parameters, and generate cross-sectional shapes that satisfy design engineers’ required characteristics. The global body stiffness and vibration property would be optimized while decreasing the mass of body. The paper describes the implementation of the optimal algorithm, and Genetic algorithms are applied to solve the optimization problem. A case of optimization for a real car is given to verify the validity of the algorithm.

Commentary by Dr. Valentin Fuster

17th International Conference on Advanced Vehicle Technologies: Advances in Methods for Ground Vehicle Systems Design

2015;():V003T01A024. doi:10.1115/DETC2015-46608.

A comparison of the lateral stability behaviour between an autonomous vehicle, a vehicle with driver and a vehicle without driver (fixed steering wheel) is made by introducing a simple mathematical model of a vehicle running on even road. The mechanical model of the vehicle has two degrees of freedom and the related equations of motion contain the nonlinear tyre characteristics. The driver is described by a well-known model proposed in the literature. The autonomous vehicle has a virtual driver (robot) that behaves substantially like a human, but with its proper reaction time and gain. The road vehicle model has been validated.

The study of vehicle stability has to be based on bifurcation analysis and a preliminary investigation is proposed here. The accurate computation of steady-state equilibria is crucial to study the stability of the three kinds of vehicles here compared. The stability of the bare vehicle without driver (fixed steering wheel) is studied in a rather complete way referring to a number of combinations of tyre characteristics. The (known) conclusion is that the understeering vehicle is stable at each lateral acceleration level and at each vehicle speed. The additional (partially unknown) conclusion is that the vehicle (model) with degradated tyres may exhibit a huge number of different bifurcations. The driver has many effects on the stability of the vehicle. One positive effect is to eliminate the many possible different equilibria of the bare vehicle and keep active one single equilibrium only. Another positive effect is to broaden the basin of attraction of stable equilibria (at least at relatively low speed). A negative effect is that, even for straight running, the driver seem introducing a subcritical Hopf bifurcation which limits the maximum forward speed of some understeering vehicles (that could run faster with fixed steering wheel). Both the mentioned positive and negative effects appear to be applicable to autonomous vehicles as well. Further studies could be useful to overcome the limitations on the stability of current autonomous vehicles that have been identified in the present research.

Commentary by Dr. Valentin Fuster
2015;():V003T01A025. doi:10.1115/DETC2015-47206.

The presented research activity is focused on the lightweight construction of a of truck wheel, with the final aim of improving the energy efficiency in compliance with current safety standards.

On the basis of the design of a truck wheel currently into production, the objective of reducing the wheel mass is achieved by adopting high-strength materials, optimizing the geometry, and developing a new production process.

The approach used for the new wheel design is based on the selection of a proper mission of the vehicle and on the acquisition of the loading spectra defined by using a new measuring wheel. The information obtained is used during the structural analysis phase. Based on the current production process, a number of suitable materials have been selected. Innovative manufacturing processes have been considered for improving the fatigue life of the wheel. Shot peening has been considered as a method to improve fatigue strength. Moreover, the introduction of laser cutting and welding led both to more freedom in the definition of the geometry of the wheel and to the reduction of the effects of geometric notches due to the absence of weld beads. A dedicated indoor test rig was used for durability tests. These activities led to a new truck wheel with reduced mass that is currently in the experimental validation phase.

Topics: Design , Wheels , Trucks
Commentary by Dr. Valentin Fuster
2015;():V003T01A026. doi:10.1115/DETC2015-47284.

This paper proposes a design development process to analyze and optimize the design of a brake rotor for a Formula Student Electric Vehicle so as to minimize its weight and reduce thermal stress by keeping the rotor within its operating temperature during the entire braking duration. In today’s world where lesser energy consumption is essential, regenerative braking plays an important role, and is also a factor in weight reduction of brake discs. Regenerative braking is an effective method to maximize brake disc’s life, minimize pad wear and extend working range of electric vehicles. The proposed technique consists of using a tire model and building mathematical models in a MATLAB environment to find transient vehicle speed, which in turn provides wheel loads, frictional torque, braking power and heat flux to the brake disc as a function of time. The heat flux to brake disc increases its temperature and is dissipated mainly through convection, which is also a time-dependent parameter based on air velocity. The entire transient heat transfer model, which also depends on the geometry, material of the brake rotor and mechanical boundary conditions is setup in ANSYS FLUENT and ANSYS Transient Structural and simulation results are presented. Stress fields for floating rotor and fixed rotor are compared since fastening techniques also play a crucial role. Disc brakes are used in almost all ground vehicles and thus, the given design process is vital as the work presented can be extended and modified as per requirements to incorporate the needs of the specific situations one needs to work upon.

Commentary by Dr. Valentin Fuster

17th International Conference on Advanced Vehicle Technologies: Advances in Methods for Tire Design and Mechanics

2015;():V003T01A027. doi:10.1115/DETC2015-46498.

Determining the parameters in existing tire models (e.g. Magic Formula (MF)) for calculating longitudinal and lateral forces depending on the tire slip is often based on standard least squares techniques. This type of optimization minimizes the vertical differences in the ordinate axis between the test data and the chosen tire model. Although the practice is to use this type of optimization in adjusting those model parameters, it should be noted that this approach disregards the errors that have been committed in the measurement of tire slips. These inaccuracies in the measured data affect the optimum parameters of the model, producing non optimum models. This paper presents a methodology to improve the fitting of mathematical tire models on available test data, taking into account the vertical errors together with errors in the independent variable.

Topics: Tires
Commentary by Dr. Valentin Fuster
2015;():V003T01A028. doi:10.1115/DETC2015-46514.

Recent advances in power and efficiency of computerized modeling methods has made it easier to develop accurate tire models. These newer models are now created with such accuracy that it has become easy to predict the experimental tire’s behavior and characteristics. These models are helpful with determining tire, tire-road, and tire-soil interaction properties. By creating virtual models, the overall capital for research and development can be reduced as well as replacing unavailable experimental tires for research.

This research paper mainly focuses on the validation of computer generated FEA tire models which are then used for the prediction of the experimental tire’s rolling resistance, static and dynamic characteristics. Experimental data, such as rolling resistance and vertical acceleration are used in validation simulations in order to tune the virtual model to match the experimental tire’s behavior. The tire that was used for this research is a six-groove 445/50R22.5 FEA truck tire, which was constructed and validated over the course of this research.

Commentary by Dr. Valentin Fuster
2015;():V003T01A029. doi:10.1115/DETC2015-46589.

The vertical stiffness of a tire is the ratio of the vertical force to the deflection; it can be expressed as the summation of the structural stiffness and air stiffness. However, the calculation of the structural stiffness is a challenging topic. This paper presents a new methodology for extracting the structural stiffness from the strain energy of a regular tire. In order to verify our proposed method, the vertical force-deflection results from the finite element method is compared with those from the strain energy method at zero air pressure. Also the results for an inflated tire are compared to calculate the structural stiffness. Finally, we calculated the contribution ratio of the tire components and used an alternative way of extracting the structural stiffness based on changing the Young’s modulus.

Topics: Stiffness , Tires
Commentary by Dr. Valentin Fuster
2015;():V003T01A030. doi:10.1115/DETC2015-46607.

The knowledge of the actual distribution of the contact forces transmitted by the tire to the rim is of crucial importance for the lightweight design of motorcycles wheels.

In this paper, an analytical model of a motorcycle tire is developed and explicit formulae giving the distribution of the static radial and axial forces acting between the tyre and the rim for a given vertical load have been derived. The analytical model has been validated by means of a FE model of the tire and wheel and on the basis of indoor experimental tests.

The proposed analytical model is able to predict the radial static deflection of both a front and a rear tire for a racing motorbike with very good accuracy over a wide range of inflating pressures and vertical loads. The force distributions are in very good agreement with the results of the FE model.

Topics: Modeling , Motorcycles , Tires
Commentary by Dr. Valentin Fuster
2015;():V003T01A031. doi:10.1115/DETC2015-46614.

Mathematical models simulating the handling behavior of passenger cars are extensively used at a design stage for evaluating the effects of new structural solutions or control systems. The main source of uncertainty in this type of models lies in the tyre-road interaction, due high nonlinearity. Proper estimation of tyre model parameters is thus of utter importance to obtain reliable results. A methodology aimed at identifying the Magic Formula-Tyre (MF-Tyre) model coefficients of the tyres of an axle based only on the measurements carried out on board vehicle (vehicle sideslip angle, yaw rate, lateral acceleration, speed and steer angle) during standard handling maneuvers (step-steers, double lane changes, etc.) is presented in this paper. The proposed methodology is based on Particle Filtering (PF) technique. PF may become a serious alternative to classic model-based techniques, such as Kalman filters. Results of the identification procedure were first checked through simulations. Then PF was applied to experimental data collected on an real instrumented passenger-car vehicles.

Commentary by Dr. Valentin Fuster
2015;():V003T01A032. doi:10.1115/DETC2015-46630.

This paper presents the validation for the newly developed in-plane flexible ring tire model by using ADAMS FTire model simulation. The developed in-plane model is unique in two aspects: (1) the neighboring belt segments are connected through normal and tangential directions by springs and dampers, each belt segment is a rigid body and its mass is accumulated at its geometric center. Each belt segment is always perpendicular to the line formed by the wheel center and the belt geometric center, thus there is no rotational constrains between the neighboring belt segments; (2) the representation of the tangential friction force between the tire and the road is defined through the multiplication of the normal contact force and the friction coefficient. And the friction coefficient is obtained based on an empirical model of the tire slip. For validation, a quarter-car model first runs on a flat road with a constant velocity (40km/h) and then rides over a rectangular shape obstacle to identify the tire parameters based on the virtual tests of Gipser’s FTire model in ADAMS. Then the quarter-car model runs on a flat road with 4–5 different conditions to ride over each obstacle: rectangular shape, triangular shape, half circle, and trapezoid. Simulation results for the new in-plane flexible ring model are compared with virtual test results from ADAMS FTire model on the same road and velocity condition for the tire patch contact forces in horizontal and longitudinal directions respectively based on the SAE standard J2812. Note that this study is the first time that the new SAE standard J2812 is used for model validation. After the validation, two important aspects have been investigated: (1) What is the minimum height of each obstacle shape so that the parameter identification will have minimum equipment loads? (2) What should the minimum number of belt segments be for each obstacle shape? The above two aspects are useful for tire model end users and tire experimental experts in real world applications.

Commentary by Dr. Valentin Fuster
2015;():V003T01A033. doi:10.1115/DETC2015-46924.

A detailed analysis of the path traversed by the rear wheels of the bus is useful in highway design, and in the placement of curbs at intersections. In fact, when a bus turns a corner, the rear wheel could move into the path of a passing motorist or pedestrian by generating an hazard situation, as in the cases of traffic circles and changing lanes. Of course, the same problems regard long trucks, semi-trailer trucks and articulated vehicles, but also bicycles (tandem) and motorbikes.

In particular, the path of the rear wheels of a bus or a long vehicle in general, is a tractrix or equi-tangential curve, which is different by that traced by the front wheels. The planar motion of the chassis of the vehicle can be represented by means of the centrodes, which are traced by the instant center of rotation on the ground (fixed centrode) and on the moving plane that is attached to the vehicle (moving centrode), respectively.

Thus, the pure-rolling motion of the moving centrode that is represented by the axis of the rear wheel, on the fixed centrode (catenary) can reproduce the planar motion of the chassis.

This paper deals with the formulation of a suitable algorithm for the kinematic analysis of the planar motion of vehicles that travel corners, traffic circles and changing lanes. The tractrix is considered as the involute of the fixed centrode (catenary), which takes also the rule of evolute. The inflection and the cuspidal or return circles, along with the Euler-Savary equation and the Aronhold Theorems, give other useful information on the planar motion of the chassis.

Commentary by Dr. Valentin Fuster
2015;():V003T01A034. doi:10.1115/DETC2015-47782.

We report on duality in stiffness values for both carbon black and silica-filled SBR-based (styrene butadiene rubber) tire rubber materials after cyclic loading (and not with no-cycle, neat samples). We believe, this behavior is due to morphological changes occurring due to cycling and not necessarily due to larger scale void/crack initiation. Causes may be chain breakage, reduced crosslinking in all samples, and agglomerate break-up/particle redistribution in silica systems, which represent early damage initiation and morphological changes in these systems. Therefore, we get a dual stiffness vs. strain behavior which is essentially superposition of two separate stiffness vs. strain curves, each being similar to the stiffness-strain curves for the neat (no fatigue) samples. We believe that the second superposed portion represents the sections deteriorated/rearranged due to cyclic loading (lower crosslinking/rearranged particle distributions) coming in-line during the straining process, and when the non-deteriorated/non-rearranged sections weaken.

Topics: Rubber , Stiffness , Tires
Commentary by Dr. Valentin Fuster
2015;():V003T01A035. doi:10.1115/DETC2015-47809.

We have demonstrated that the X-ray Micro-CT (Computed Tomography – 3D) method can be used to progressively assess damage/flaw presence and progression in SBR-based (styrene butadiene rubber) tire rubber materials. Our experimental results reveal that progression of flaws due to cyclic (fatigue) loading may not occur at a fast rate until a catastrophic failure occurs in the tire material.

Topics: X-rays , Rubber , Tires , Damage
Commentary by Dr. Valentin Fuster

17th International Conference on Advanced Vehicle Technologies: Advances in Military and Commercial Ground Vehicle Design

2015;():V003T01A036. doi:10.1115/DETC2015-46342.

To address the lack of knowledge on the quantitative effects of Personal Protective Equipment (PPE) on the small occupant, 55 drop tower tests were conducted and the resulting responses were evaluated. A previous technical publication evaluated the results of drop tower testing of twelve models of blast energy-attenuating seats1. That study assessed the data recorded from three sizes of anthropomorphic test devices, or ATDs, including the Hybrid III 5th percentile female, the Hybrid III 50th percentile male, and the Hybrid III 95th percentile male. The forces, moments, and accelerations from the ATDs were compared to Injury Assessment Reference Values (IARVs) to validate the drop tower methodology and to evaluate the appropriateness of the IARVs developed for the three occupant sizes. The data review revealed that the maximum lumbar compression loads recorded by the ATDs was an effective “go/no-go” criteria for judging seat performance, and that the 5th percentile female ATD, or small occupant, was the most difficult to pass the corresponding lumbar compression IARV. Additionally, the 5th percentile female ATD exceeded its corresponding IARV for upper neck compression, leading to the motivation for this study; the data set from the previous technical publication was used in this study.

Historically, blast mitigation seats are designed to accommodate the average sized occupant, or 50th percentile male. Moving forward, there is a new emphasis on extending the protection afforded to the full military population, including the small female. The data presented in this paper seeks to determine the effect of PPE on the lumbar compression and upper neck loads for the small occupant.

Commentary by Dr. Valentin Fuster
2015;():V003T01A037. doi:10.1115/DETC2015-46367.

Crash testing and validation of Military vehicles has not to date, accounted for the Soldier gear burden. Actual loads imparted onto the occupant in a representative Military vehicle crash test environment have been limited and do not reflect what an occupant would actually see in this type of an event. The US Army Soldier encumbered with his gear poses a challenge in restraint system design that is not typical in the automotive world. The weight of the gear encumbrance may have a significant effect on how the restraint system performs and protects the occupant during a frontal event. Other system level complications to Military vehicle interiors are secondary impact surfaces, such as instrument panels, ammunition cans and weaponry which provide a path for off-loading the energy generated by the occupant and gear combination. The energy absorption of these surfaces however, is not ideal in current Military vehicle designs and may result in injury or death.

The goal of this study was to investigate gear and accelerative pulses as they relate to the restraints and occupant interaction. Data from this study will be used for further restraint development. To limit experimental variation a fixed steel seat structure was utilized throughout the entire testing series. It is hypothesized that determining these effects will lead to a restraint system design that can be optimized to provide restraint for the whole range of occupant sizes and gear variations. Further reductions in occupant injury are achieved by properly tuning the surrounding trim, air bags and cargo contact surfaces.

Results of this study indicate the inclusion of the soldier gear may increase the likelihood of occupant excursion and injury. Variation in accelerative pulses resulted in lower injury values and occupant displacements.

Topics: Gears , Soldiers
Commentary by Dr. Valentin Fuster
2015;():V003T01A038. doi:10.1115/DETC2015-46798.

For military all-terrain vehicles, there is a need to radically increase tactical and operational mobility through new modalities by fundamentally improving vehicle terrain control. By characterizing the tire relaxation length and time constants for lateral and longitudinal dynamic changes, mobility control can be enhanced to accommodate agile tire dynamics.

This paper analyzes the transient period of the tire reaction force development process, which is characterized by the relaxation length, for the purpose of agile tire dynamics control as a pre-emptive, fast and exact response of a tire to dynamic changes of its interaction with terrain. In this regards, a comprehensive literature review was undertaken and the tire relaxation length was analyzed for different types of vehicles and their operational velocities. The time relaxation constants, which are derived from the relaxation length, are determined and analyzed based on the data gathered in technical literature. Based on the analysis, reference magnitudes of the time relaxation constants are proposed to be used in agile tire dynamics control algorithm and hardware developments of military all-terrain vehicles.

Commentary by Dr. Valentin Fuster
2015;():V003T01A039. doi:10.1115/DETC2015-47805.

The use of experimental and numerical investigation to predict the aerodynamic characteristics of road vehicles is a standard practice in automotive design and development. Fundamental research has been often conducted on generic models with limited applicability to realistic cars. The DrivAer model developed in TU München possesses more representative car features. To encourage the use of the DrivAer model in independent research work, the experimental results and some numerical results were published.

In this paper, a new developed wind tunnel setup of the DrivAer model was introduced. A new suspension system was designed in such a way that drag and lift force could be measured whilst the wheels are rolling on the moving ground without wheel struts (In this paper we call it wheels-on setup). The more close-truth experimental results of different rear end configurations were obtained. The lift force of the total model was firstly obtained. Additionally, the influences of the wheel struts and top sting were studied.

Numerical investigation for performing finite-volume-based Reynolds-averaged Navier-Stokes (RANS) for the prediction of aerodynamic forces of passenger vehicles developed was presented, using the open-source CFD toolbox OpenFOAM®.

Validation of the predictions was done on the basis of detailed comparisons to experimental wind tunnel data, both of the basic body (wheelhouse covered and without wheels) and the new wheels-on model. Results of drag coefficient were found to compare favourably to the experiments.

Topics: Aerodynamics
Commentary by Dr. Valentin Fuster
2015;():V003T01A040. doi:10.1115/DETC2015-48078.

The transmission efficiency of a multi-range hydro-mechanical continuously variable transmission (HMCVT) is researched, which considered the factors of the power cycle and the efficiency variation of hydraulic units with their input power and speed. An efficiency algorithm of the closed pump-motor system is given, which is relative to the speed, pressure and displacement of hydraulic units. Efficiency formulas of typical structures of HMCVT are derived by meshing power method. The efficiency of a multi-range HMCVT is calculated. The calculated efficiency is consistency with the measured efficiency. The result shows that the average efficiency of HMCVT is reasonably higher than the peak efficiency of pure hydraulic transmission, although the efficiency varies obviously with the transmission ratio, the input power or torque. When the output torque of engine is smaller, the efficiency of HMCVT is lower. However, the speed change of engine has a less influence on the efficiency of HMCVT.

Commentary by Dr. Valentin Fuster

17th International Conference on Advanced Vehicle Technologies: Advances in Vehicle Electrification and Powertrain Design

2015;():V003T01A041. doi:10.1115/DETC2015-46206.

Fuel saving technology can be pursued in many different forms, such as gearing mechanism improvement to powertrain system optimization. With the increasing maturity and availability of sensing technologies such as GPS, motion-detecting sensors, and wireless communications, the vehicle powertrain system design community is embracing these information sources by developing mobile platforms for efficiency improvement. In this paper, a self-contained system architecture is presented that integrates the digital map database, radar senor, V2x, and mobile traffic data from the wireless network for commercial vehicle driver assistance. Each data source utilizes a different communication protocol. As such, the system integration can be challenging and may involve significant investment including engineering development if a suitable system architecture is not defined. This paper introduces a single board computer (SBC) based architecture to integrate these sensors with the powertrain system as a cost-effective implementation. Finally, some field testing data will be presented to show the benefits of using look-ahead information for improving the freight efficiency.

Topics: Vehicles
Commentary by Dr. Valentin Fuster
2015;():V003T01A042. doi:10.1115/DETC2015-46754.

A systematic analysis methodology is proposed to design the suitable three-mode configurations based on the lever model. Based upon the torque and speed relationship among four powertrain elements, three suitable configurations are selected. In designing dual-mode powertrain, method of adding the number of PG and the DOF of configuration are applied based on the compound split mode. On the basis of dual-mode powertrain, three-mode powertrains are designed though adding input split in low speed ratio or compound split in high speed ratio. Comparing the relationship of motor’s speed and torque in dual-mode and three-mode powertrains separately, the structure which has low requirements for motors is selected.

Commentary by Dr. Valentin Fuster
2015;():V003T01A043. doi:10.1115/DETC2015-46939.

Development of electric vehicle (EV) technology leads to the growing performance requirements of driving motor. Introducing a two-speed transmission to EV offers the possibility of economic and dynamic performance improvement of the whole powertrain. This paper presents an innovative two-speed Uninterrupted Mechanical Transmission (UMT), allowing the seamless shifting between two gears. Considering the uncertain factors during gearshift, a robust controller is designed based on H∞ control method. An optimal controller based on linear quadratic regulator is adopted for comparison. The results indicate that the UMT adopting robust controller provides an improvement of dynamic performance and shifting comfort for EV.

Commentary by Dr. Valentin Fuster
2015;():V003T01A044. doi:10.1115/DETC2015-47030.

An integrated electro-mechanical drive train component for heavy duty vehicles in off-road applications is presented. The component utilizes a two-step transmission and a tooth-coil permanent magnet motor and has compact size enabling in-wheel installation. The driveline design procedure is surveyed to explore the advantages of a geared electric motor in electric drivelines. Multibody dynamic simulation is applied to verify the functionality of the driveline. A vehicle generic model that is compatible with a multibody simulator program is developed to describe the performance of the proposed driveline in different vehicles. A co-simulation procedure is applied to combine the electric motor and vehicle body simulation models. It is shown that the co-simulation can be performed in real-time, thus enabling a human driver to control the vehicle. A comparison is made of the rear wheel drive and wheel mounted electric motor from the efficiency and performance points of view. The power consumption of vehicles with different driveline architectures is calculated to diagnose the weak points of the system and enhancement solutions are proposed.

Commentary by Dr. Valentin Fuster
2015;():V003T01A045. doi:10.1115/DETC2015-47521.

Satisfying human needs means to respond directly to human choice / human commands at the time of purchase, in real time operation, for maintenance / tech mods over the life history of the vehicle, and for refreshment in the future hybrid electric vehicles (HEV) equipped with four-independent in-wheel motors (IWM). This leads to maximizing human choice. To meet human choice means not only to keep the human fully informed on a series of choices, but also to maximize their self-awareness.

Meeting human choice requires visual performance maps. Based on the future HEV with an open (modular) architecture, visual performance maps help customers make right choices what they want, so that a vehicle can be tailored to a particular customer priority such as cost and drivability for an aggressive driver. This paper demonstrates how different types of an IWM are matched to different types of customers. The decision framework developed in this paper is based on detailed human needs structured by performance maps to visually guide the customer in terms of purchase / operation / maintenance / refreshment decisions. Part I is focused on purchase criteria, while Part II discusses operation / maintenance / refreshment criteria.

Topics: Motors , Wheels
Commentary by Dr. Valentin Fuster
2015;():V003T01A046. doi:10.1115/DETC2015-47566.

Part I of this paper demonstrated how different human choices affect the selection of all basic components of a Hybrid Electric Vehicles (HEV) equipped with four-independent In-Wheel Motors (IWM) based on detailed human needs structured by visual performance maps to guide the customer in terms of purchase criteria: cost, weight, power, acceleration, gradeability, braking, handling, ride comfort, efficiency, and durability.

This Part II discusses ten operation criteria: cornering force margin, roll angle, sideslip angle, lateral acceleration, slip angle, yaw rate, acceleration force margin, braking force margin, pitch angle, and travel range. These visual performance maps show the effects of HEV weight on acceleration, braking, and cornering maneuvers under various road conditions (i.e., dry asphalt, wet asphalt, snowy or icy road) which are evaluated and compared based on the implementation of a nonlinear 14 DOF full-vehicle model based on ride (7 DOF), handling (3 DOF), tire (4 DOF), slip ratio, slip angle, and the tire magic formula. In addition, this paper demonstrates how different human choices affect the HEV’s expected performance. Lastly, maintenance and refreshment criteria are presented and explained.

Topics: Maintenance , Motors , Wheels
Commentary by Dr. Valentin Fuster
2015;():V003T01A047. doi:10.1115/DETC2015-47980.

The transfer case based all-wheel drive electric vehicle (TCAWDEV) and dual-axle AWDEV have been investigated to balance concerns about energy consumption, drivability and stability of vehicles. An ideal AWDEV (IAWDEV) powertrain architecture is proposed by this research; the architecture has an independent driving motor at each wheel; in essence, the IAWDEV is a distributed powertrain that provides various combinations of torque vector control. This research also investigated the simplified methods to estimate the battery capacity and the operation envelope of motors, and employed model-based evaluation approaches to recursively identify the proper powertrain components. The model-based evaluation was conducted in LMS AMESim. The results show that the IAWDEV could reduce the complexity of drivetrain, and also can harvest more braking energy under poor road contact.

Commentary by Dr. Valentin Fuster
2015;():V003T01A048. doi:10.1115/DETC2015-48062.

In the last years hybrid Transmissions have spread worldwide in the automotive industry due to their excellent power performance and good fuel economy. The design of parallel hybrid automatic manual transmission (AMT) with electric torque support using one electric motor is a good solution of obtaining high transmission efficiency and low manufacturing cost. The gear pairs between the combustion engine (CE) shaft and electric motor (EM) shaft are assigned to form the new architecture of three degrees of freedom (DOFs) AMT with electric torque support, which provides several CE gears ratios and several EM gears ratios. All theoretical layouts of parallel hybrid AMT with three shafts are presented and classified into four types. And the synthesis of the gear ratios sequence is developed to satisfy power shifting. The gear ratios can be divided into direct gear ratio and generated gear ratio. The ratio design of generated gear is dependent on the ratio of the direct gears, so the design of gear ratio can be transformed into the solution of over-determined nonlinear equations. An algorithm of minimax solution for over-determined nonlinear equations is presented to design and evaluate gear ratios. The three-DOF three-shaft AMT with electric torque support are designed to obtain seven CE gear ratios. This paper helps to further the understanding of the systematic design of parallel hybrid AMT with electric torque support.

Topics: Torque , Design
Commentary by Dr. Valentin Fuster

12th International Conference on Design Education: Building in Design and Advanced Manufacturing

2015;():V003T04A001. doi:10.1115/DETC2015-46470.

The Innovation Station is a 3D printing vending machine that provides on-demand, internet-enabled 3D printing to all students on The University of Texas at Austin campus. It was designed and built by the authors, who also operate the machine throughout the academic year. This paper introduces the Innovation Station and describes insights and lessons learned from operating the machine for its first academic semester. User statistics and common user mistakes are described, and a designer’s guide is provided to make it easier for first-time users to 3D print successfully.

Commentary by Dr. Valentin Fuster
2015;():V003T04A002. doi:10.1115/DETC2015-46651.

One requirement in our sophomore design class is for the students to work in teams to design and build devices that satisfy several requirements subject to physical constraints. The evaluation of these devices is based on how individuals and the team perform on written documents as well as how well the device performs during testing and satisfies given design criteria. The performances in various parts of this assignment are used as a basis for student outcomes assessment. The paper will provide an example of a team project description including the figure of merit that assesses the functionality of the device and the rubric used to assess the quality of the design in four areas:

• creativity demonstrated in the design concept,

• creativity demonstrated in the execution of the concept,

• overall craftsmanship and esthetics, and,

• robustness,

plus a sales brochure.

Examples of student work and assessment documentation will also be provided.

Topics: Design
Commentary by Dr. Valentin Fuster
2015;():V003T04A003. doi:10.1115/DETC2015-47274.

Accompanying the increasing advances and interest in Additive Manufacturing (AM) technologies is an increasing demand for a workforce that is knowledgeable about the technologies and how to employ them to solve engineering problems. As a step towards addressing this knowledge gap, a workshop was held at the National Science Foundation (NSF) to discuss the educational needs of, and opportunities for, developing an AM workforce. With the goal of developing novel educational partnerships to better prepare and enhance the AM workforce, the workshop participants — 66 representatives from academia, industry, and government — sought to answer questions such as “What should we teach to the AM workforce and why?”, “To whom and how should we teach AM?”, and “How should we partner for AM education and training?” Key educational themes that emerged include: (1) AM processes and process/material relationships, (2) engineering fundamentals with an emphasis on materials science and manufacturing, (3) professional skills for problem solving and critical thinking, (4) design practices and tools that leverage the design freedom enabled by AM, and (5) cross-functional teaming and ideation techniques to nurture creativity. The paper summarizes the speaker presentations and outcomes from the workshop, along with several new educational partnerships identified by small working groups. Based on the presentations and partnerships, we recommend the following to advance the AM workforce. First, ensure that all AM curricula provide students with an understanding of (i) AM and traditional manufacturing processes to enable them to effectively select the appropriate process for product realization; (ii) the relationships between AM processes and material properties; and (iii) “Design for AM”, including computational tools for AM design as well as frameworks for process selection, costing, and solution generation that take advantage of AM capabilities. Second, establish a national network for AM education that, by leveraging existing “distributed” educational models and NSF’s ATE Programs, provides open source resources as well as packaged activities, courses, and curricula for all educational levels (K-Gray). Third, promote K-12 educational programs in STEAM (STEM plus the arts) and across all formal and informal learning environments in order to leverage the unique capabilities of AM in engaging students in hands-on, tactile, and visual learning activities. Fourth, provide support for collaborative and community-oriented maker spaces that promote awareness of AM among the public and provide AM training programs for incumbent workers and students seeking alternative pathways to gain AM knowledge and experience. Recommendations for scaling and coordinating these activities across local, regional, and national levels are also discussed to create synergies among the proposed activities and existing efforts.

Commentary by Dr. Valentin Fuster
2015;():V003T04A004. doi:10.1115/DETC2015-47388.

The objective of this paper is to test the hypothesis that immersive virtual reality environments such as those achievable through the head-mounted displays, enhance task performance in online engineering design activities. In this paper, task performance is measured by the time to complete a given engineering activity. Over the last decade, a wide range of virtual reality applications have been developed based on non-immersive and immersive virtual reality systems for educational purposes. However, a major limitation of non-immersive virtual reality systems is the lack of an immersive experience that not only provides content to students, but also enables them to interact and learn in a completely 360 degree immersive environment. The authors of this work have developed a replica of a physical engineering laboratory in an interactive virtual learning environment. This research measures the difference in task performance between i) students exposed to an immersive virtual reality system and ii) students exposed to a non-immersive virtual reality system, in the interactive virtual environment developed by the research team. This research seeks to explore whether statistically significant differences in performance exist between these groups. Knowledge gained from testing this hypothesis will inform educators about the value and impact of immersive virtual reality technologies in enhancing online education. A case study involving 54 students in a product functional analysis task is used to test the hypothesis.

Commentary by Dr. Valentin Fuster
2015;():V003T04A005. doi:10.1115/DETC2015-47417.

This paper describes a three semester long project which promotes the development and retention of engineering skill-sets by involving students in the design and fabrication of a can-crushing device. The can-crusher project was inspired by spiral learning theory and provides opportunities for students to practice engineering skill sets, including CAD, programming, machining and working with practical electronics. The paper details the implementation of the project and shows how the project addresses skill-set deficits that can occur in conventional curricula. Finally, modifications to the content/organization of the can-crusher project are proposed based on the experiences of the first group of students to complete the three semester sequence.

Topics: Design
Commentary by Dr. Valentin Fuster

12th International Conference on Design Education: Creativity and Innovation

2015;():V003T04A006. doi:10.1115/DETC2015-46492.

We report four cases from a larger study, focusing on participants’ self-identified “most creative” concept in relation to their other concepts. As part of an ideation session, first-year engineering students were asked to create concepts for one of two engineering design problems in an 85-minute period, and were exposed to one of two different forms of fixation. Participants worked as individuals, first using traditional brainstorming techniques and generating as many ideas as possible. Design Heuristics cards were then introduced, and students were asked to generate as many additional concepts as possible. After the activity, participants ranked all of the concepts they generated from most to least creative. Representative cases include a detailed analysis of the concept that each participant rated as “most creative,” idea generation method used, and relative location and relationship of the concept to other concepts generated by that participant. Across four cases, we identified a number of characteristic “misrules” or misconceptions, revealing that first-year students judge creativity in their concepts in ways that could inhibit their ability to produce truly novel concepts. We present Design Heuristics as a tool to encourage the exploration of creative concept pathways, empowering students to create more novel concepts by rejecting misrules about creativity.

Commentary by Dr. Valentin Fuster
2015;():V003T04A007. doi:10.1115/DETC2015-46542.

Conventional syllabi of engineering design courses either do not pay enough attention to conceptual design skills, or they lack an objective assessment of those skills to show students’ progress. During a semester-long course of advanced engineering product design, we assigned three major design projects to twenty five students. For each project we asked them to formulate the problems in the Problem Formulator web-based testbed. In addition, we collected sketches for all three design problems, feasibility analyses for the last two, and a working prototype for the final project. We report the students’ problem formulation and ideation in terms of a set of nine problem formulation characteristics and ASU’s ideation effectiveness metrics respectively. We discuss the limitations that the choice of the design problems caused, and how the progress of a class of students during a semester-long design course resulted in a convergence in sets of metrics that we have defined to characterize problem formulation and ideation. We also review the results of students of a similar course which we reported last year in order to find common trends.

Commentary by Dr. Valentin Fuster
2015;():V003T04A008. doi:10.1115/DETC2015-47650.

Multiple research studies have examined the role of the undergraduate engineering curriculum on students’ innovation capabilities. The majority of these studies have used cross-sectional samples to compare students at the beginning and end of their college careers, and most results have shown that seniors outperform freshmen. In the following paper, we use a combination of cross-sectional and longitudinal comparisons to uncover when innovation capabilities grow. Over a two-year period, undergraduate engineering majors at different points in their college careers completed concept generation tasks. Their resulting concepts were scored for originality. While no difference was found from freshman to senior year using a cross-sectional comparison, a significant increase in originality was found between separate senior groups at the beginning and end of a capstone course. The difference between the senior groups occurred despite no difference between these students in academic performance or engineering design self-efficacy. In addition, a significant increase in originality was found from junior to senior year using a longitudinal analysis. This increase in originality occurred without corresponding changes in academic performance or engineering design self-efficacy. These results are discussed in relation to prior research regarding the interplay between curricular and individual difference factors in the development of students’ innovation capabilities.

Commentary by Dr. Valentin Fuster

12th International Conference on Design Education: Methods to Aid Learning

2015;():V003T04A009. doi:10.1115/DETC2015-46617.

In this work we present the results of hands-on design experience implemented in an undergraduate mechanical engineering design course. This work is motivated by the need to provide students with more design-decision making experience to enable them to be ready to engineer upon graduation. Students were guided through the process of designing learning aid prototypes to be used in general engineering education. Three significant results of this work are that: 1) 3D printing was a critical technology for enabling authentic learning environments; 2) Student’s grasp of fundamentals is improved through construction of learning aids compared to their typical classroom use; and 3) Setting limits on resources and client’s time are necessary but require flexibility to enable “learning through failures.” Overall this work demonstrates a structured approach to using additive manufacturing as integrated technology in engineering education.

Topics: Design , Students
Commentary by Dr. Valentin Fuster
2015;():V003T04A010. doi:10.1115/DETC2015-46873.

Many educators agree that developing an interdisciplinary design curriculum is critical in creating the next generation of design professionals. However, literature surrounding the pedagogical challenges to undergraduate interdisciplinary design courses is limited. In this paper we study the initial challenges in developing and delivering an interdisciplinary design course. We observe from the perspective of the educators and the students in a newly synthesized co-taught design course that combines both architecture and engineering disciplines.

Through exploratory observations and analysis of student and instructor feedback throughout the semester, our findings suggest that disciplinary boundaries often influence pedagogical styles despite a concerted effort to create an interdisciplinary course that focuses on design. Despite agreement to interdisciplinary design teaching through shared lectures and activities, individual teaching methods varied, impacted by pedagogical norms from their respective disciplines. In response, students had mixed reactions to the varying presentation methods and critique feedback. This study, while preliminary in assessment, raises many questions about the challenges of teaching interdisciplinary design courses.

Topics: Design , Teaching
Commentary by Dr. Valentin Fuster
2015;():V003T04A011. doi:10.1115/DETC2015-46952.

Today, it is common for design engineers around the world to work in distributed teams on a shared project. However, their exposure to shared projects is limited in academia as it poses a series of challenges. This paper explores teams of students working in a design project with its members located in the United States and Chile. During the yearlong study, students tracked their hourly dedication to team tasks while solving a common cross-cultural challenge: designing products to improve mobility in aging populations. To see if team diversity contributed to innovative solutions, teams of students worked in an orchestrated manner, within their regions for a whole academic period. Over a second semester, students from both geographic regions interacted as distributed teams to face the design challenge. Data of the duration and timing of each of the teams design activities and final products were collected. The data were explored to seek similarities and differences between co-located and distributed teams. The effect of distributed teams on product development is discussed, and the challenges and benefits of this practice are explored. Also, recommendations are given for future studies regarding distributed teams.

Topics: Design , Teams , Students
Commentary by Dr. Valentin Fuster
2015;():V003T04A012. doi:10.1115/DETC2015-46978.

In helping students learn engineering design, it is very important that they explore complex scenarios that are realistic, and fall outside the domain of standard and over-simplified textbook problems that typically have an answer. A majority of the current educational methods and computer-based tools do not bridge this gap and lack affordances for design exploration. Although computational methods such as Finite Element Analysis have this potential, they are hard to use requiring the users to spend a significant effort. Also, several instructors have identified significant knowledge gaps in concepts related to structural design and strength of materials when the students reach their senior year. To this end, we have developed a problem-based framework to allow for rapid design exploration within engineering design curricula using an easy-to-use, simplified and constrained version of finite elements for stress analysis and exploration. Our framework makes it possible for users to rapidly explore various design options by incorporating a Finite Element Analysis (FEA) backend for design exploration. Our approach uses a constrained design problem for weight minimization that incorporates elements of structural topology optimization but does not automate it. Instead we provide the user the control on decision making for changing the shape through material removal. Using this framework, we explore the decision making of users, and their methodology in the course of the activities that provide a context of control, challenge and reflection. Using video and verbal protocol analysis we integrate assessment in ways that are important and interesting for learning. Our framework demonstrates that the ability of computational tools that are transformed for learning purposes can scaffold and augment learning processes in new ways.

Commentary by Dr. Valentin Fuster
2015;():V003T04A013. doi:10.1115/DETC2015-47276.

Project-based education in combination with problem-based learning has been very successful, and has contributed to the popularity of engineering design education among students at technical universities. The close connection to industrial problems by the use of industry-connected projects has boosted this popularity still further and to get an insight of future working environments after graduation is very inspiring for the students.

The curriculum of the Machine Design capstone course at KTH Department of Machine Design covers the whole process from idea generation to manufacturing and testing a final prototype. A major part of the course consists of project work where students develop a product prototype in close cooperation with an industrial partner or with a research project at the department. This means that a major part of the course uses project-based learning as a teaching strategy. In addition, a model-based design methodology is introduced which enables the students to evaluate and “experience” many different behaviors of the product using digital models in a virtual environment. In this way, students can see that many undesirable concepts and flaws can be avoided even before a prototype is manufactured.

This paper evaluates the use and learning outcome of model-based design in a capstone course in the Engineering Design MSc program at KTH Department of Machine Design. The approach has been used during a period of three years and the effect on the students’ learning has been evaluated by a questionnaire after each course. I this paper we compare the results of these questionnaires and discuss implications and general conclusions about this learning approach.

Commentary by Dr. Valentin Fuster

12th International Conference on Design Education: New Topics and Content in Design Courses

2015;():V003T04A014. doi:10.1115/DETC2015-46172.

Uncertainty is ubiquitous in engineering, but it is not taught in most of engineering courses. One of the major problems is the lack of proper teaching materials. The objective of this project is to create an Engineering Repository with teaching and learning materials so that they can be adopted in various engineering courses. We at first discuss the basics of uncertainty and the need of uncertainty education. We then report the current status of the development of the Engineering Repository and its use in classes of Dynamics and Probabilistic Engineering Design. Several examples of the Engineering Repository are also presented.

Topics: Uncertainty
Commentary by Dr. Valentin Fuster
2015;():V003T04A015. doi:10.1115/DETC2015-47312.

Additive Manufacturing (AM) is a revolutionary technology in the manufacturing sector, although it has yet to become a cornerstone of formal engineering education. This paper discusses the procedure, result, and impact of incorporating physical prototyping, design iteration, and Design for Additive Manufacturing (DfAM) in a first-year, first-semester technical drawing and CAD course. In the course, students design balloon powered model car assemblies and are expected to learn core concepts of engineering design, such as modeling, assemblies, and tolerancing. The course consists of 473 students that each design up to two unique model cars. These model cars are fabricated using AM from these CAD designs and returned to students for assembly. Surveys are given to students to empirically validate the usefulness of incorporating AM in the course, with regards to motivating students and improving their ability to accurately translate imagined designs from CAD to physical products. The results show improvement in student intrinsic motivation concerning CAD processes. Student design abilities are also assessed: when student designs do not function as intended, it corresponds with a greater mismatch in how they imagine their CAD design in comparison to its final physical assembly. The mismatch on average decreases for students who design a second model car, which suggests an improvement in design skills. As a whole, our findings demonstrate the feasibility and benefits of including AM in a first-year course, particularly with respect to improving student motivation and their development of key CAD-related skills. Such motivation and skill development is particularly important early in an engineer’s career as it can impact their potential to learn and design over the course of their budding career.

Commentary by Dr. Valentin Fuster
2015;():V003T04A016. doi:10.1115/DETC2015-47396.

In design research, creativity assessment methods have been studied to obtain quantitative measurements of design novelty and feasibility for use in the concept selection process. However, little research exists that studies the application and implementation of these tools by engineering students on grade-dependent class projects. In this study, teams of undergraduate engineering design students evaluated their own early product sketches using informal team discussions, a creativity scale and our Tool for Assessing Semantic Creativity (TASC) adjective selection method. The resulting evaluations were compared and contrasted with evaluations obtained from the widely adopted Shah Vargas-Hernandez and Smith (SVS) method and expert ratings. These findings demonstrate that our TASC adjective selection method of evaluating design creativity is tapping into similar constructs of creativity as informal team discussions and expert evaluations. They also indicate that the SVS method does not appear to be evaluating creativity as perceived by engineering design students or experts. The results of this study can be used to understand how students make decisions during the concept selection process and how tools can be developed or implemented in the classroom setting to aid in this process.

Commentary by Dr. Valentin Fuster
2015;():V003T04A017. doi:10.1115/DETC2015-47604.

This paper presents the findings of a study comparing the motivational factors and performance of two mechanical engineering senior capstone design course cohorts: 2014 and 2015 students. The study measures the motivation of students throughout capstone, a non-traditional course, and the impacts motivation had on their course performance (peer evaluations and team grade). The second cohort participated in an intervention plan during a design methodologies course completed the semester prior to senior capstone design. Quantitative data was collected at both the beginning and end of the course; whereas, qualitative data was collected at the end of the course. Our method utilizes an adapted version of the Motivational Student Learning Questionnaire (MSLQ). The survey asks a variety of questions to measure the performance and motivation levels of the student. Performance factors studied are cognitive value and self-regulation. Motivation factors include presentation anxiety, intrinsic value, and self-efficacy. Statistical analysis is performed among the factors, cohort populations, and within the population (male versus females and domestic versus international) to identify if a correlation exists with student course performance. Amongst other findings, the results indicate the student’s experienced positive change due to participation in the intervention plan.

Topics: Design , Students
Commentary by Dr. Valentin Fuster

12th International Conference on Design Education: Short Papers: Design Education Innovations

2015;():V003T04A018. doi:10.1115/DETC2015-46646.

The subject course has as its central focus a design and build project that draws its context from addressing problems faced by a mythical Gondwannan population. Through it, students are exposed to an authentic design experience across a range of technical domains in an integrated semester long process. They grapple with user needs, requirements analysis, concept and detail design reviews and prototype demonstration. The course, as run at the University of New South Wales, Canberra, is described in the paper and the facilitation of the course academically and physically is discussed.

Topics: Design
Commentary by Dr. Valentin Fuster
2015;():V003T04A019. doi:10.1115/DETC2015-46778.

The School of Mechanical, Industrial, and Manufacturing Engineering at Oregon State University is home to one of the largest academic Mechanical Design groups in the country. As a leader in undergraduate design education, we have been able to keep in touch with a large group of mechanical design graduates, and as such are capable of assessing how students retain information learned in undergraduate coursework to see how this understanding is employed in real-world engineering practice. However, the principles governing the design of sustainable products and processes are relatively novel and are only now being integrated into the undergraduate and graduate mechanical design curriculum. It is our hypothesis that particular means of learning and understanding sustainable design — via lectures, homework assignments, design projects, and the use of various sustainability-related LCA tools — will enable the highest retention of sustainable design understanding, and a higher likelihood that this sustainable design knowledge will be propagated into design practice in industry. Multiple curricular studies that explore dissemination and retention of sustainable design skills are being explored, including a junior-level introductory mechanical design course and a graduate level sustainable product development course. In the junior-level course, baseline sustainability knowledge is tested by allowing students to make sustainable design decisions by applying varied skill sets, including general principles, a list of sustainable design guidelines, and an innovative online survey (The GREEn Quiz). The graduate-level course, which employs sustainable design principles within a larger product development architecture, will capitalize on more “expert” knowledge. Future work will also be discussed, including planned validation studies and curriculum improvements, as well as the means of quantifying the retention of sustainable design information.

Commentary by Dr. Valentin Fuster
2015;():V003T04A020. doi:10.1115/DETC2015-47286.

Freshman/sophomore design projects provide students with hands-on experiences in conceptual design and manufacturing. For some of these courses, a design competition is used to teach the design and construction components. These competitions are often reused from semester to semester, so the students typically suffer from design fixation. When design competition tables are erected new every single semester, it requires advanced planning and high budgets. This paper discusses a case study of a different structure for introductory design courses and competitions at Harvard. We summarize a yearlong effort to improve an existing early design competition with more machine component elements and linkage design. The goal of a interchangeable design competition was to prevent design fixation while at the same time providing boundaries for students to successfully implement their robot designs, independent of their previous mechanical engineering exposure.

Commentary by Dr. Valentin Fuster
2015;():V003T04A021. doi:10.1115/DETC2015-47455.

Lab exercises have traditionally been a time when students follow a given procedure, collect data, and interpret the data. The highly structured experience often leads to students focusing on the procedure and not fully thinking through the concepts being covered. While labs are fully completed each week, the structured approach does not prepare students for the open-ended, non-procedural work entry-level engineers will encounter in industry. To encourage a deeper understanding of course concepts and how they translate to physical systems and better prepare students for the workforce, open-ended design projects were offered in place of structured labs in the circuits and mechatronics courses at James Madison University.

The design projects are undirected experiences that build on the directed experiences in lecture and lab. Students are challenged to work in teams to design, build, test, and in one case, calibrate, an electrical system. No instruction is provided for the project, rather, a set of design requirements, timetable, and supplemental materials (e.g., data sheets, vendor design briefs, past labs relevant to the design requirements) are given. Students must synthesize multiple weeks of course content into a single design project. This paper reports on our observations and student feedback for embedding design experiences in engineering science courses.

Commentary by Dr. Valentin Fuster
2015;():V003T04A022. doi:10.1115/DETC2015-47622.

A lack of knowledge of how to design products specifically for Additive Manufacturing (AM, also referred to as “3D Printing”) is often viewed as a barrier to industrial adoption of the technology. To advance the AM workforce, the author hosted a 10-week university-wide extracurricular competition that challenged students to design, build, and operate remotely piloted ground and air vehicles made entirely via AM and a standardized electronics kit. The context of the competition was guided by the Department of Defense’s shared vision for forward deployment of AM systems to provide agile on-site part production and reduction of supply chain complexity. The competition vehicles were designed to allow future deployed military or civilian engineers to fabricate remotely-piloted vehicles while in battlefield or austere environmental conditions, such as the site of a natural disaster to search for survivors or to carry out reconnaissance missions. The competition served as unique informal learning environment that engaged over 200 students in the emerging principles of “design for Additive Manufacturing” (DfAM). In this paper, the author presents an overview of the competition structure, and the results of preliminary assessment of the students’ gains in design learning.

Commentary by Dr. Valentin Fuster
2015;():V003T04A023. doi:10.1115/DETC2015-47792.

In this paper, the new graduate course, referred to as “Creation and Innovation”, for interdisciplinary design and innovation is introduced based on the collaboration between arts and engineering. In this course, students having various backgrounds in arts and engineering schools participates and forms several interdisciplinary teams for project-based learning. The systematic methods such as Design Thinking Process and Strategic Foresight and Innovation have been combinatorially adopted for this course. Those methods are human-centered approaches, which allow deep understanding on users’ needs and wants by being empathized with users and their environments. This empathy activity can enable the students to actively consider users’ various aspects, which has been of much significance in the current interdisciplinary design education. It is also shown that the collaboration among the team members with the backgrounds of arts and engineering can be effective to generate more creative and innovative ideas by combining their holistic and analytic views.

Commentary by Dr. Valentin Fuster

12th International Conference on Design Education: Thinking in Design

2015;():V003T04A024. doi:10.1115/DETC2015-46126.

Based on the available evidence from published literature, we reviewed the effectiveness of Course-based Undergraduate Research Experiences (CUREs). In many cases, CUREs present open-ended, complex problems that student teams tackle. Our review of 41 published articles, additional archival research, and semi-structured interviews identified multiple benefits of CUREs, including their ability to introduce larger numbers of students to research than is possible within traditional, apprenticeship-style models for undergraduate research experiences. We identified outcomes of CUREs as well as obstacles to their successful implementation. We recommended a set of features for consideration for future CURE implementers. A brief comparison of CURE with REU, or Research Experience for Undergraduate, is also included in the paper.

Commentary by Dr. Valentin Fuster
2015;():V003T04A025. doi:10.1115/DETC2015-46334.

This paper examines ideation variety as a measure of the extent to which a design solution space has been explored. We investigated one cognitive factor (cognitive style) and one cognitive intervention (Design Heuristics cards) and their relationships with students’ ideation variety, both actual and perceived. Cognitive style was measured using the Kirton Adaption-Innovation inventory (KAI), while variety scores were computed using the metrics of Nelson et al. [18] and Shah et al. [20]; an adapted form of these metrics was also explored. A group of 132 sophomore mechanical engineering students generated ideas for two design problems (one with and one without Design Heuristics cards). They sketched and described their conceptual solutions in words and assessed the variety of their solutions after ideation. Linear statistical techniques were applied to explore the relationships among the variety scores, students’ self-assessments of variety, cognitive style, quantity of ideas, and the presence of the Design Heuristics intervention. Our results show statistically significant correlations between students’ perceived variety and their variety performance, and between cognitive style and both variety performance and student perceptions.

Commentary by Dr. Valentin Fuster
2015;():V003T04A026. doi:10.1115/DETC2015-47379.

In this paper, we present a technology assisted flat learning environment, Teaching to Learn (TeatoL), where all participants have dual roles as students and instructors. The main objective of this work is to investigate how peer-to-peer information exchange aids in bridging knowledge gap in a flat-learning environment. We present our TeatoL implementation that was developed to enhance ill-structured problem solving skill along with its assessment. The participants in the learning environment were given an open design problem related to sheet metal forming. A short lecture about 35 minutes (Phase 0) was given and then student teams were asked to make an instructional video (Phase I) describing their approach for solving the open-ended problem. The videos were viewed by peers, using their computers and mobile devices. The students then critiqued and provided feedback on the posted videos (Phase II). The final step of the process had students write short reports on their problem solving approach (Phase III) that was modified based on peer-to-peer interactions. Student learning in all three phases was assessed to understand the effects of different modes of learning in TeatoL. Our findings indicate that TeatoL is an effective flat online learning environment. Correlation analysis suggests that learning gains are dependent on the level of knowledge on the topic for the learning community (class) and the number of meaningful comments provided by peers. The findings from this work can be utilized to develop technology based online peer learning environments to improve learning outcomes through active collaborative learning. Such an environment can be particularly useful for open course delivery.

Commentary by Dr. Valentin Fuster
2015;():V003T04A027. doi:10.1115/DETC2015-47843.

To support the development of TheDesignExchange — a portal to a comprehensive set of design methods applicable to a range of disciplines — we hosted a series of workshops with design students, educators and practitioners. In this paper, we summarize insights gained from the three practitioner workshops associated with early stage design methods used to: Research, Analyze and Communicate. We contrast the practitioner feedback with insights from previous workshops with design students and educators. We also discuss implications for enhancing professional skills and industry practice into design education.

Topics: Design
Commentary by Dr. Valentin Fuster
2015;():V003T04A028. doi:10.1115/DETC2015-47922.

Nature is a powerful resource for engineering designers. The natural world provides numerous cases for analogy and inspiration in engineering design. Transferring the valuable knowledge and inspiration gained from the biology domain to the engineering domain during concept generation is a somewhat disorganized process and relies heavily on the designers’ insight and background knowledge of many fields to make the necessary leaps between the domains. Furthermore, the novice designer approaching biology for inspiration tends to focus heavily on copying the visual attributes of a biological system to develop a solution that looks like the biological system rather than explore at deeper levels to uncover relationships that lead to the development of true analogies.

There are now well-known methods for teaching bioinspired design in engineering and the majority of methods prescribe the use of analogies in order to facilitate knowledge transfer, however, guidance in analogy formulation to foster the creative leaps is missing or ill defined. Thus little is known about how students use biological systems for design inspiration. This paper proposes categories for analogical knowledge transfer in bio-inspired design to foster and characterize diverse analogical knowledge transfer. The proposed analogy categories are used to describe the behavior seen in an engineering class. Results indicate that (1) single biological system provides multiple analogies that result in different engineering inspiration for design; (2) biological information from multiple categories is transferred during concept generation; and (3) non-physical characteristics may inspire more sophisticated engineering inspiration than those based on physical characteristics alone. Overall, the analogy data classification has resulted in a better understanding of analogical knowledge transfer during bio-inspired design and leads to best practices for teaching bio-inspired design to engineering students.

Topics: Design , Biomimetics
Commentary by Dr. Valentin Fuster

8th Frontiers in Biomedical Devices: Computational Modeling and Simulation

2015;():V003T14A001. doi:10.1115/DETC2015-46165.

In this paper, a physically motivated micromechanical model for connective soft tissues like tendon and ligament is presented. A representative volume element (RVE) is introduced based on the crimped pattern of collagen fiber in the tissue. In order to investigate the macroscopic behavior of tissue, numerical homogenization and appropriate periodic boundary conditions are used. Neglecting the effects of nano scale structures and properties on tissues macroscopic behavior leads to linear transversely isotropic model for collagen fibers. Comparison of obtained result with available experimental one, shows that this assumption leads to inaccurate results. Including the effects of nano scale structures into the presented model leads to a nonlinear transversely isotropic constitutive model for collagen fibers which leads to results that are in good agreement with experimental results.

Commentary by Dr. Valentin Fuster
2015;():V003T14A002. doi:10.1115/DETC2015-47373.

The closed head impact (CHI) rat models are commonly used for studying the traumatic brain injury. Although various impact parameters (e.g., impact depth, velocity, and position) have been investigated by a number of researchers, little is known about the effects of the impactor shape, diameter, and material on the internal responses of the rat brain. In this work, numerical CHI experiments were conducted to investigate the sensitivities of intracranial responses to the impactor details such as impactor shape, diameter, and material. A 3D finite element rat head model with anatomical details was subjected to impact loadings. Results revealed that the impactor shape can affect the intracranial responses significantly. The effect of impactor diameter on the intracranial responses in different brain regions was uniform. In addition, careful attention should be paid when using an extremely compliant material for the impactor, since the actual impact depth might be compensated by the impactor deformation.

Topics: Brain
Commentary by Dr. Valentin Fuster
2015;():V003T14A003. doi:10.1115/DETC2015-47878.

Low-trauma hip fracture, usually caused by fall from standing height, has become a main source of morbidity and mortality for the elderly. Factors affecting hip fracture include sex, race, age, body weight, height, body mass distribution, etc., and thus, hip fracture risk in fall differs widely from subject to subject. It is therefore necessary to develop a subject-specific biomechanical model to predict hip fracture risk. The objective of this study is to develop a two-level, image-based, subject-specific biomechanical model consisting of a whole-body dynamics model and a proximal-femur finite element (FE) model for more accurately assessing the risk of hip fracture in lateral falls. Required information for constructing the model is extracted from a whole-body and a hip DXA (Dual Energy Xray Absorptiometry) image of the subject. The proposed model considers all parameters subject-specifically, which will provide a fast, accurate, and non-expensive method for predicting hip fracture risk.

Commentary by Dr. Valentin Fuster
2015;():V003T14A004. doi:10.1115/DETC2015-47958.

The structural topological optimization method is an effective way to find the optimal topology of stents, which could be tailored for targeted stent performance, such as scaffolding ability, foreshortening, potential restenosis rate, etc. The radial stiffness is one of the major characteristics about stent performance. In this work, the homogenization method was utilized for the optimization of stent designs with the objective of maximizing the scaffolding ability of stent, i.e. its radial stiffness. A few design choices were presented by changing the number and distribution of strut connectors while keeping the void volume as 80%. The obtained optimal topology illustrated that the material distribution was mainly determined by the radial stress applied onto the stent. The optimal topology design in this work paves the way for the following dimension design, which can be targeted to the customized stent design for patient-specific lesions.

Topics: Optimization , stents
Commentary by Dr. Valentin Fuster
2015;():V003T14A005. doi:10.1115/DETC2015-48052.

Low-trauma hip fracture, usually caused by fall from standing height, has become a main source of morbidity and mortality among the elderly. However, the hip fracture risk is subject-dependent as it is related to the subject’s anthropometric parameters, the kinematic/kinetic variables in fall, and the hip anatomy. A compound fracture risk indicator is proposed in this study to define the correlation between the hip fracture risk and subject’s parameters such as anthropometric parameters, bone mineral density (BMD), height of body mass center (HMC), and hip soft tissue thickness (STT). In this study, a two-level, subject-specific biomechanical model composed of a whole-body dynamics model and a proximal femur finite element model was used to predict the hip fracture risk for 80 subjects. The required information was obtained from the subject’s whole body and hip DXA (dual energy X-ray absorptiometry) images. Then, multivariate nonlinear least-square fits of power functions were used to investigate the effect of parameters on hip fracture risk. Results indicated that although BMD is the dominant parameter affecting the hip fracture risk, other parameters such as hip soft tissue thickness and anthropometric parameters also have considerable effects. This finding suggests that the hip fracture risk cannot be accurately predicted by the currently available single factor predictors as they do not consider all multifactorial parameters. However, the proposed function can properly predict the risk of hip fracture in the absence of any computational simulation and biomechanical model. It also quantifies the effect of musculoskeletal-, and organ-level parameters on hip fracture risk and demonstrates which individual is more likely to experience hip fracture.

Topics: Hip fractures , Risk
Commentary by Dr. Valentin Fuster

8th Frontiers in Biomedical Devices: General Biomedical Devices

2015;():V003T14A006. doi:10.1115/DETC2015-46254.

This paper describes an automatic system for analyzing phantom images from two types of PET/CT scanners. The system was developed for the purpose of obtaining tomographic image quality parameters, which determine a number of different performance parameters, primarily scanner sensitivity, tomographic uniformity, contrast and spatial resolution. The system provides a method for generating and altering image masks used for the analysis of PET images, which are then automatically aligned with the PET data. The system automatically generates Quality Control (QC) reports and is currently being used at clinical PET/CT center.

Topics: Reliability , Phantoms
Commentary by Dr. Valentin Fuster
2015;():V003T14A007. doi:10.1115/DETC2015-46296.

Low-cost label-free bio-sensing systems have long been desired to enable rapid, sensitive, quantitative, and high-throughput biosensing for bio-medical and chemical applications. Here we present an optical bio-detection system consists of injection-molded biosensors based on double-sided grating waveguide couplers and an optical intensity-based detection platform for low-cost, real-time, and label-free biosensing. The biosensors were fabricated combining injection-molding and sputtering techniques, providing unique advantages of low-cost and reduced production time. A simple and cost-effective optical intensity-based detection system employing a low-cost light emitting diode and a simple photodetector is also developed to perform label-free biosensing. We demonstrate that a high refractive index resolution of 6.43 × 10−5 RIU is achieved with this compact bio-sensing system, showing great promises for low-cost, real-time, label-free detection in bio-medical and chemical applications.

Commentary by Dr. Valentin Fuster
2015;():V003T14A008. doi:10.1115/DETC2015-46826.

In this paper, concept of developing a haptic tele-robotic master-slave manipulators for ultrasound imaging examination, and some preliminary results will be presented. In a tele-ultrasound system the motion of a master manipulator (such as a haptic wand or a simple joystick) which carries a virtual probe is controlled by a medical expert and remotely reproduced at the patient site by a slave robot, carrying the ultrasound probe. In general a remote diagnostic system contains three divisions: expert station (or expert site), patient station (or patient site), and a communication network such as servers Wi-Fi or satellite network. The experiments demonstrate that the slave manipulator is capable of successfully following the motion of a master manipulator in a path following as well as for point-to-point motions.

Commentary by Dr. Valentin Fuster
2015;():V003T14A009. doi:10.1115/DETC2015-46997.

This paper documents the design and validation of a measurement tool for chronic wound assessment. Using the Google Glass™ head-mounted display (HMD) as a platform for research, we developed a digital ruler to dynamically capture wound dimensions in a hands-free manner. The system consists of the Glass HMD equipped with an infrared light emitting diode (IR-LED) distance sensor, lithium polymer battery, and a custom printed circuit board. Programmed using Android 4.4.2 (API 19), orthogonal rulers along the X and Y axes are superimposed on the Glass eyepiece and calibrated for measurement accuracy. To evaluate system performance, we conducted an ANOVA Gage Repeatability and Reproducibility (R&R) analysis with six wound care nurses measuring seven artificial wounds of various dimensions, two times each. Data was analyzed using Minitab statistical software. For width measurements, the results indicate that the total Gage R&R percent contribution was 10.2%, with 4.2% attributed to equipment variation (repeatability) and 6.0% to operator variation (reproducibility). Wound-to-wound variation was 89.8%. For length measurements, the total Gage R&R percent contribution was 16.7%, with 14.1% attributed to equipment variation and 2.6% to operator variation. Wound-to-wound length variation was 83.3%. The system received positive feedback from nurses as a hands-free measurement tool for sterile wound handling. Yet, further refinements are needed to improve system accuracy and depth measurement capabilities.

Topics: Design
Commentary by Dr. Valentin Fuster
2015;():V003T14A010. doi:10.1115/DETC2015-47451.

Technological advancement in cell and microscopy imaging generate a high demand for complex image analysis techniques. Image processing techniques are powerful tools to assess the images and extract information for quantization and evaluation of regions. It is crucial to develop advanced automatic cell segmentation methods with capability to analyze image data with high level of accuracy. In this paper, a quantitative technique is developed to count the number of cells from phase contrast microscopy. The technique selects region of interests (ROI) in the cell images and it measures the cell locations within ROI in a specific microfluidic device. The cell location is an important factor which will affect the flow pattern in the microfluidic device and consequently induced shear stresses.

Commentary by Dr. Valentin Fuster
2015;():V003T14A011. doi:10.1115/DETC2015-47567.

A direct cardiac compression (DCC) device is a non-blood contacting sleeve placed around the failing heart to actively assist blood pumping function. For design optimization of a DCC device, it is necessary to monitor the surface pressure exerted on the heart surface at multiple points during active assist, and to correlate this with device performance and cardiac output. In this paper, we present the design, fabrication and characterization of a soft, elastic, conformable pressure sensing sleeve that is placed at the heart/device interface to monitor device performance without affecting device function. This sleeve enables identification of optimal pre-tensioning, positioning and user-controlled parameters of the DCC device. Individual sensors (8×8×3 mm) were fabricated using a surface mount device (SMD) barometer on a custom double-sided flexible printed circuit board and casting the assembly in urethane rubber. A typical sensor has a dynamic range of 2.5 kPa to 50 kPa with a sensitivity of 11.3 counts per kPa. An array of up to 24 sensors was integrated into a flexible, stretchable circuit embedded in a thin (500 micron) silicone sheet using a multi-step layering fabrication process. Continuous magnet wires were wrapped around an alignment fixture, soldered to individual sensors in place and the entire circuit was transfer printed on to a silicone sheet. This assembly allows stretch corresponding to the fractional shortening of the heart muscles (up to 50%). The sleeve successfully measured static and dynamic pressures with a mechanical tensile tester and did not affect DCC device performance. Preliminary results demonstrated that the sleeve is robust enough to withstand >10000 cycles, compression forces from the DCC device and can achieve sensing range and repeatability suitable for procedural pressure monitoring for a DCC device. In addition to allowing performance measurements for iterating DCC device designs, the sensing sleeve can enable increased understanding of the response of the cardiovascular system to compressive assistance.

Topics: Pressure , Compression
Commentary by Dr. Valentin Fuster
2015;():V003T14A012. doi:10.1115/DETC2015-47620.

Phlebotomy is a routine task, performed over a billion times annually in the United States alone, that is essential for proper diagnosis and treatment. We designed and constructed Phlebot, a robotic assistive device that uses a novel combination of near-infrared (NIR) monocular imaging and force-feedback to guide a needle into a forearm vein for blood sample collection or intravenous catheterization. Through initial validation on phantoms, we show that our approach offers a feasible and reliable method to automate phlebotomy. We envision the device to be a first major step towards more affordable point-of-care testing and diagnostic healthcare systems. In the long term, we expect that Phlebot will expedite healthcare delivery and drastically reduce needle stick injuries, instances of hemolysis, and infections caused by blood-borne pathogens.

Topics: Robotics
Commentary by Dr. Valentin Fuster
2015;():V003T14A013. doi:10.1115/DETC2015-47655.

Research has suggested that elevated intracranial pressure (ICP) can cause damage to the optic nerve and reduce visual acuity. There is a need for noninvasive ICP monitoring devices. A simple, portable device capable of measuring relative changes in ICP using a noninvasive methodology would have a significant impact on clinical care. The methodology presented in this paper utilizes transcranial Doppler ultrasonography to monitor ophthalmic artery hemodynamics while small forces are applied to cornea. In vivo testing using a porcine model results in a correlation between pulsatility or resistivity indices and ICP levels. Specifically, the change in these indices while force is applied decreases as ICP increases. The data collection prototype used in these experiments contained an ultrasound transducer instrumented with a load cell to measure force applied to the cornea. These experiments are an initial step towards adapting the data collection prototype into a handheld noninvasive ICP monitoring device.

Topics: Testing
Commentary by Dr. Valentin Fuster
2015;():V003T14A014. doi:10.1115/DETC2015-47671.

This paper provides a systematic review of over 350 publications that document specific medical device examples in which the design and manufacturing relied on additive manufacturing processes (more popularly referred to as “3d Printing”). Existing reviews on 3d printing for medical device design focus on the range of clinical applications and potential uses for this technology. However, existing work tends to omit key medical device development and regulatory requirements pertaining to the use of 3d printing for technology translation. These omissions often present a skewed view of each device’s potential for rapid translation to commercialization and common clinical practice.

To fill gaps in existing literature, this review includes medical device journal articles and identifies each article’s country of origin, the product development stage in which 3d printing was used, and the device’s specific type and classification under the U.S. Food and Drug Administration. The findings from this systematic review provide a detailed international snapshot of current additive manufacturing research and its near term potential for changing clinical practice.

Commentary by Dr. Valentin Fuster

8th Frontiers in Biomedical Devices: Orthopedics and Rehabilitation

2015;():V003T14A015. doi:10.1115/DETC2015-46229.

This paper presents the mechanical design and evaluation of a knee-ankle-foot robot, which is compact, modular, and portable for stroke patients to carry out overground gait training at outpatient and home settings. The robot is driven by a novel series elastic actuator (SEA) for safe human-robot interaction. The SEA employs one soft translational spring in series with a stiff torsion spring to achieve high intrinsic compliance and the capacity of providing peak force. The robotic joint mechanism and the selection of the actuator springs are optimized based on gait biomechanics to achieve portability and capability. The robot demonstrated stable and accuracy force control in experiments conducted on healthy subjects with overground walking. Major leg muscles of the subjects showed reduced level of activations (Electromyography, EMG) while maintaining normal gait patterns with robotic assistances, indicating the robot’s capability of providing effective gait assistance.

Commentary by Dr. Valentin Fuster
2015;():V003T14A016. doi:10.1115/DETC2015-46343.

Patellofemoral disorders have been recognized as one of the major causes of the human knee articulation problems. In general, the current available methods to assess patellofemoral joint disorders include the analysis of clinical history, clinical tests and imaging exams. These approaches are ambiguous in the diagnosis produced since they strongly depend on the expertise of the examinant. With the purpose to assist in the diagnosis process of the patellofemoral disorders, a new medical device is proposed throughout this work. In the sequel of this process, the identification and full characterization of the main issues associated with patellofemoral joint are presented. The main features and the engineered solution are accuracy and reproducibility, possibility of incorporation into imaging equipment, adaptability to a large range of knee sizes, easy and cheap to manufacture and anatomically and ergonomically fashion. The mechanical system designed and built allows for the measurement and quantification of the most significant patellofemoral joint motions, more precisely the medial-lateral translation, internal-external tilt and internal-external rotation. The validation of the medical device is investigated here by analyzing the data produced from actual clinical exams, being the early results quite satisfactory and very promising for extensive use in helping in the diagnosis of the patellofemoral disorders.

Commentary by Dr. Valentin Fuster
2015;():V003T14A017. doi:10.1115/DETC2015-47720.

Recognition of user’s mental engagement is imperative to the success of robotic rehabilitation. The paper explores the novel paradigm in robotic rehabilitation of using Passive BCI as opposed to the conventional Active ones. We have designed experiments to determine a user’s level of mental engagement. In our experimental study, we record the brain activity of 3 healthy subjects during multiple sessions where subjects need to navigate through a maze using a haptic system with variable resistance/assistance. Using the data obtained through the experiments we highlight the drawbacks of using conventional workload metrics as indicators of human engagement, thus asserting that Motor and Cognitive Workloads be differentiated.

Additionally we propose a new set of features: differential PSD of Cz-Poz at alpha, Beta and Sigma band, (Mental engagement) and relative C3-C4 at beta (Motor Workload) to distinguish Normal Cases from those instances when haptic where applied with an accuracy of 92.93%. Mental engagement is calculated using the power spectral density of the Theta band (4–7 Hz) in the parietal-midline (Pz) with respect to the central midline (Cz). The above information can be used to adjust robotic rehabilitation parameters I accordance with the user’s needs. The adjustment may be in the force levels, difficulty level of the task or increasing the speed of the task.

Commentary by Dr. Valentin Fuster

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