0

ASME Conference Presenter Attendance Policy and Archival Proceedings

2013;():V06BT00A001. doi:10.1115/DETC2013-NS6B.
FREE TO VIEW

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to ASME’s conference presenter attendance policy, if a paper is not presented at the Conference, the paper will not be published in the official archival Proceedings, which are registered with the Library of Congress and are submitted for abstracting and indexing. The paper also will not be published in The ASME Digital Collection and may not be cited as a published paper.

Commentary by Dr. Valentin Fuster

37th Mechanisms and Robotics Conference: Novel Mechanisms, Robots and Applications

2013;():V06BT07A001. doi:10.1115/DETC2013-12107.

Dynamic balancing generally involves the static balancing of a mechanism using countermasses followed by the dynamic balancing of the inertia using counter-rotations. This approach requires that the statically balanced mechanism have a constant inertia for any configuration. Two of the main drawbacks of dynamic balancing are a significant increase in mass and actuation inertia. In this paper, static balancing strategies are optimized regarding the addition of mass and actuation inertia using Lagrange multipliers. The results are optimal mass-inertia curves which are akin to Pareto curves. Optimal static balancing rules are obtained and a comparison of balancing strategies shows that relaxing the constant inertia constraint may significantly reduce the total mass and actuation inertia. Then, a counter-mechanism is introduced in order to dynamically balance a mechanism with variable inertia. The conditions for which the counter-mechanism matches the inertia of the main mechanism for any configuration are derived. The significant influence of the radius of gyration of the counter-inertias on the optimal mass-inertia curves is revealed. Additionally, the advantages of counter-mechanisms over counter-rotations are demonstrated. Finally, examples of dynamically balanced mechanisms and a prototype are presented in order to illustrate the concepts.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A002. doi:10.1115/DETC2013-12186.

Shape-Shifting Surfaces (SSSs) are multilayered surfaces that are able to change shape while maintaining their integrity as physical barriers. SSSs are composed of polygonal unit cells, which can change side lengths and corner angles. These changes are made possible by each side and corner consisting of at least two different shields, or layers of material. As the layers undergo relative motion, the unit cell changes shape. In order for the SSS to retain its effectiveness as a barrier, no gaps can open between different layers. Also, the layers cannot protrude past the boundaries of the unit cell. Based on these requirements, a design space exploration was performed to determine, using equilateral triangle unit cells and triangular shields, the maximum deformation range of a unit cell. It was found that the triangular shields with maximum allowable deformation were right triangles with one of the angles being equal to 37.25 degrees and the adjacent side equal to 61% of the side length of the unit cell. The key contribution of this paper is a first algorithm for systematic SSS shield design. Possible applications for SSSs include protection, by creating body-armor systems; reconfigurable antennas able to broadcast through different frequencies; recreational uses, and biomedical applications.

Topics: Design , Shapes
Commentary by Dr. Valentin Fuster
2013;():V06BT07A003. doi:10.1115/DETC2013-12411.

A compound load simulator has drawn increasing attention due to the growing demand for testing of critical components in mechanical devices. However, its development is still limited owning to the shortage of corresponding design principle. Accompanied with the application of parallel mechanisms in a variety of multi-axis machine tools and motion simulators, it brings new inspiration to this field. Although existing six degree-of-freedom (DOF) parallel mechanisms such as Stewart platform can output multi-dimensional loads, it also produces the complexity of force control and inevitable collaborative error. Actually, it is enough to utilize deficient-DOF mechanisms for a majority of load patterns and practical engineering applications. Therefore, this paper mainly focuses on synthesizing deficient-DOF parallel/hybrid compound load simulators. Regular load types are summarized including one-dimensional generalized force and compound of them. Based on characteristics of each load type, DOF of the moving platform connecting to the component to be tested is determined through the mapping between force and displacement in rigid body motion. Current typical deficient-DOF parallel mechanism is enumerated to evaluate its load output characteristics. What is more important, a type synthesis procedure based on the graphic approach is presented to construct the configurations of parallel/hybrid mechanism corresponding to different compound load types, which may lead to useful load simulator configurations. The procedure also verifies that the graphic approach is a concise and effective method to synthesize the load simulators associated with a specified load pattern.

Topics: Stress
Commentary by Dr. Valentin Fuster
2013;():V06BT07A004. doi:10.1115/DETC2013-12479.

Flapping wing air vehicles offer many useful flight characteristics due to their versatility, as proven by flying animals. Wing design significantly influences the performance. However designing successful wings presents significant challenges. Efficient matching of the drive motors to the flapping wings is necessary to overcome the highly constrained weight budget. Simulating detailed information about the force response due to flapping is challenging due to complex fluid-structural interactions of the wings resulting in non-linear force response to flapping motion. To overcome this challenge, we conducted an experimental study of flapping wings to provide detailed temporal force response data for flapping wings. A prototype was built by synthesizing lightweight manufacturing techniques with the results of the experimental study. Our experimental investigations enabled us to select the flapping angle range and flapping frequency.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A005. doi:10.1115/DETC2013-12502.

The coupling between two opposite bars of the hinged parallelogram produces relative 1-DoF circular translation and the opposite bars can move but remain parallel. From the point of view of kinematics, a hinged parallelogram is equivalent to a prismatic pair for a small motion. On the basis of a special parallel mechanism with the limb architecture of type CPUh (C and P denote cylindrical and prismatic pairs; Uh indicates the pseudo-universal-joint having one revolute and one screw pairs with the intersecting axes), we provide one novel Schoenflies-motion isoconstrained CPaUh//CPaUh robot with only two limbs having the hinged parallelograms for the fast pick-and-place operation of the assembly and packaging applications. This type of robot is compact for not only its structure but also its actuation. The robot architecture and kinematics including inverse and forward solutions are studied. In addition, Jacobian matrix, singularity analysis and workspace are further discussed. It is hoped that the evaluations of such two-limb parallel mechanism can be useful for possible application in industry where pick-and-place motion and higher accuracy are required.

Topics: Robots
Commentary by Dr. Valentin Fuster
2013;():V06BT07A006. doi:10.1115/DETC2013-12682.

Tolerances on line-profiles are used to control cross-sectional shapes of parts, even mildly twisted ones such as those on turbine or compressor blades. Such tolerances limit geometric manufacturing variations to a specified two-dimensional tolerance-zone, i.e. an area, the boundaries to which are curves parallel to the true profile. The single profile tolerance may be used to control position, orientation, and form of the profile.

For purposes of automating the assignment of tolerances during design, a math model, called the Tolerance-Map (T-Map), has been produced for most of the tolerance classes that are used by designers. Each T-Map is a hypothetical point-space that represents the geometric variations of a feature in its tolerance-zone. Of the six tolerance classes defined in the ASME/ANSI/ISO Standards, only one attempt has been made at modeling line-profiles [1], and the method used is a kinematic description, based largely on intuition, of the allowable displacements of the middle-sized profile within its tolerance-zone. The result presented is a 4-D double pyramid having a 3-D shape for the common base. Allowable small changes in size represent the fourth dimension in the altitude-direction of the pyramids. However, that work is limited to square, rectangular, and right-triangular profile shapes for which the 3-D transverse sections (called hypersections) of the 4-D T-Map are all geometrically similar to the base because the boundaries are doubly traced. For more generally shaped profiles, [2] the hypersections are not geometrically similar to the base.

The objective of this paper is to expand the kinematic description of a profile in its tolerance-zone to include the changing constraints that take place as size is incremented or decremented within the allowable tolerance-range. It provides validation of a different method that is described in a companion paper [3].

Topics: Kinematics
Commentary by Dr. Valentin Fuster
2013;():V06BT07A007. doi:10.1115/DETC2013-12741.

A novel approach of dynamic, non-contact measurement of joint parameters using the planar Vestibular Dynamic Inclinometer (pVDI) is proposed in this paper. The gravity-invariant planar Vestibular Dynamic Inclinometer (pVDI) is a non-contact sensor that consists of symmetrically placed four dual-axis accelerometers and one tri-axial gyroscope. The deployment of the non-contact sensor is strategic and need not be at the joints. The paper proposes measurement of joint parameters — base angle, joint angle, angular velocity and angular acceleration, that are independent of integration errors/drift.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A008. doi:10.1115/DETC2013-12795.

The Second Spine is a vest intended to prevent musculoskeletal injuries caused by heavy backpack loads, while also maintaining the range of motion of the wearer. The vest is formed by multiple segments between the shoulder and a pelvic belt. In normal “off” configuration, the segments are disconnected from each other and the vest is flexible providing full range of motion to the upper body. With the pull of a string in the “on” configuration, the vest becomes semi-rigid creating a secondary pathway to transfer loads between the shoulder and a pelvic belt.

The device was evaluated by a subject who walked on a treadmill while carrying a backpack load of 25% of his body weight (BW). Experiment results showed that the semi-rigid vest reduces the force exerted on the shoulders and induces a more erect posture. Muscle activations in the lower limbs indicate that loads were successfully transferred from the shoulders to the waist while bypassing the vertebral column. These results show that the device can be used to mitigate potential risks of musculoskeletal injuries caused from backpack loads.

Topics: Stress , Design
Commentary by Dr. Valentin Fuster
2013;():V06BT07A009. doi:10.1115/DETC2013-12885.

Shape–controlled adaptable buildings constitute a major excursion from traditional architectural approaches with a potential for superior performance and enhanced flexibility compared to traditional fixed–shape building structures. A building concept is examined whose skeleton structure consists of a parallel arrangement of planar closed–loop n–bar linkages and it is covered with a flexible material. Shape adjustments involve coordinated reconfigurations of the constituent closed–chain mechanisms. Each individual linkage is equipped with one motion actuator as well as brakes installed on every joint. For the reconfigurations an “effective 4–bar” concept has been proposed that involves stepwise adjustments. Each step involves the selective locking of (n – 4) joints of each linkage so that it is effectively reduced to a single–DOF 4–bar mechanism the configuration of which can be adjusted using the available motion actuator. Appropriately planned control sequences can be used for a complete reconfiguration of the linkage. Motion planning is concerned with the generation of optimal control sequences while taking into account imposed limitations arising from the moving structure as well as the flexible envelop. This paper is a continuation of a prior work paying special attention to the envelop design. Simulation examples as well as an experimental study are used to demonstrate the feasibility of the concept and investigate relevant issues.

Topics: Structures , Robotics , Shapes
Commentary by Dr. Valentin Fuster
2013;():V06BT07A010. doi:10.1115/DETC2013-12898.

In legged mobile robotics the most common approach is to design fully actuated legs with several degrees of freedom (DOF) in order to successfully navigate through rough terrains. However, simpler leg architectures with as few as one-DOF have been developed in the past to achieve the very same goal. The ability of these simpler legs to traverse uneven terrains is arguably limited with respect to multi-DOF designs, but in some applications the reduction of the DOF and hence, of the number of actuators, as well as the simplicity of the associated control could be a great advantage and the decisive argument. In this paper, the authors propose a novel one-DOF robotic leg that has been specially designed to achieve the greatest robustness possible with respect to the difficult terrains it has to traverse. In order to do that, a method to analyze and optimize any one-DOF robotic leg with respect to its ability to overcome obstacles is proposed here. This method is based on a simple and efficient novel technique to generate synthetic terrains combined with a simulation algorithm estimating the traversability of the particular one-DOF leg design under scrutiny. To illustrate the generality of the proposed method, it is used to design both an optimal leg with the architecture presented here for the first time and also, one with the most common one-DOF leg architecture found in the literature.

Topics: Robotics
Commentary by Dr. Valentin Fuster
2013;():V06BT07A011. doi:10.1115/DETC2013-12938.

Docking mechanisms are an integral part of modular self-reconfigurable robot (MSR) systems, allowing multiple robot modules to attach to each other. An MSR should be equipped with robust and efficient docking interfaces to ensure enhanced autonomy and self-reconfiguration ability. Genderless docking is a necessary criterion to maintain homogeneity of the robot modules. This also enables self-healing of a modular robot system in the case of a failed module. The mechanism needs to be compact and lightweight and at the same time have sufficient strength to transfer loads from other connected modules. RoGenSiD is a rotary-plate genderless single sided docking mechanism that was designed to perform robustly and efficiently considering its application in unstructured terrains. The design methodology followed design for manufacture (DFM) and design for assembly (DFA) guidelines as well as considerations for minimal space and weight. As a result, this docking mechanism is applicable for multi-faceted docking in lattice-type, chain-type, or hybrid MSR systems. Bench-top testing validated the system performance.

Topics: Robots
Commentary by Dr. Valentin Fuster
2013;():V06BT07A012. doi:10.1115/DETC2013-12948.

Intrinsically safe mechanisms represent an innovative solution to develop physical human-robot interactions. These systems are characterized by low masses, inertia and torques. In this paper, an innovative actuation strategy is presented, focused on safety concerns. The system is first statically balanced to compensate gravity forces in any configuration. Our contribution then lies in the design of a mechanism that modifies the system balancing, making it possible to follow a planned trajectory or to remain in contact with a moving environment, without developing large forces. This principle is illustrated with an elementary one degree of freedom arm. The whole design procedure is described, so as to define properly the arm parameters for a given task. A closed loop position control strategy is then proposed in order to drive the mechanism. It uses a proportional-derivative controller with configuration dependent gains, whose efficiency is illustrated by trajectory following and interaction simulations.

Topics: Robots
Commentary by Dr. Valentin Fuster
2013;():V06BT07A013. doi:10.1115/DETC2013-13150.

This paper reports ongoing work on the design of a new gripper for garments handling. The development of this device is part of the CloPeMa European Project creating a robot system for automated manipulation of clothing and other textile items. First, we analyze the specificity of the application determining the requirements for the design and functioning of the grasping system. Textiles do not have a stable shape and cannot be manipulated on the basis of a priori geometric knowledge. The necessary exploration of the material and the environment is performed with the help of tactile sensors embedded in the fingertips of the gripper, complementing the vision system of the robotic work cell. The chosen design solution is a simple mechanism able to perform adequately the grasping task and to permit exploratory finger motions. The kinematics and statics of the mechanism are outlined briefly and, in accord with initial experiments, used to validate the design.

Topics: Grippers
Commentary by Dr. Valentin Fuster
2013;():V06BT07A014. doi:10.1115/DETC2013-13187.

This paper presents a novel deployable mechanism. Unlike most deployable structures, which have one degree of freedom, the proposed device can be deployed and compacted independently in two directions. This widens the range of its potential applications, including flexible industrial fixtures and deployable tents. The mechanism’s basic deployable unit is assembled by combining a scissor linkage and a Sarrus linkage. The kinematic properties of the two component linkages and the combined unit are analyzed. The new deployable mechanism is obtained by linking the deployable units. The Mobility and kinematics are analyzed. The relationship between the degree of overconstraint and the number of deployable units is derived. The magnification ratio is calculated as a function of the geometry of the link and the number of deployable units. Finally, kinematic simulations are performed to validate the proposed design and analysis.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A015. doi:10.1115/DETC2013-13225.

Mobile robotic devices and other mobility related drive systems are often relegated to one of the two classes of devices available today: wheeled devices or tracked devices. Wheeled systems are more energy efficient and reliable than tracked systems, but existing designs have drawbacks related to rough-terrain driving and maneuvering in tight spaces.

In this paper we describe the design and development of a drive system named the Single Motor Propelled Drive-train (SiMPl-D), which can potentially improve maneuvering over rough terrain and in tight spaces compared to traditional wheeled robots. SiMPl-D has two prominent features: a single drive motor, which provides both propulsion and turning, and is suspended under the center of mass of the device on a swingarm, which is linked through a suspension system to caster wheels; and it has reconfigurable drive wheel, which changes the turning radius of the device.

Due to these features, SiMPl-D can traverse a wide range of terrain while remaining energy and cost efficient. SiMPl-D has been successfully used in an indoor/outdoor low-cost personal mobility device and is currently being implemented in other robotic mobility applications.

Topics: Engines , Design , Trains
Commentary by Dr. Valentin Fuster
2013;():V06BT07A016. doi:10.1115/DETC2013-13345.

This paper details the development of an open-source surface electromyographic interface for controlling 1-DOF for the DARwIn-OP humanoid robot. This work also details the analysis of the relationship between surface electromyographic activity of the Biceps Brachii muscle and the angle of the elbow joint for the pseudo-static unloaded arm case. The human arm was mechanically modeled for a two link system actuated by a single muscle. The SEMG activity was found to be directly proportional to joint angle using a combination of custom joint angle measuring hardware and a surface electromyographic measuring circuit. This relationship allowed for straightforward control of the robot elbow joint directly. The interface was designed around the Arduino Microcontroller; another open-source platform. Software for the Arduino and DARwIn-OP were drawn from open source resources, allowing the entire system to be comprised of open-source components. A final surface electromyographic measuring and signal conditioning circuit was constructed. Data recording and processing software was also coded for the Arduino, thus achieving control of the robotic platform via surface electromyography.

Topics: Humanoid robots
Commentary by Dr. Valentin Fuster
2013;():V06BT07A017. doi:10.1115/DETC2013-13358.

In this paper, we propose an underactuated robotic finger whose grasp behavior is modulated by the design of its superelastic joints. Using shape-memory alloy, the finger joints can be given specific stiffness and pre-form shapes such that a single-cable actuation rather than opposing-pair actuation can be used; this also allows the grasping motions of the phalanges to be synchronized in the free phase and then adaptive once contact is made. A default-closed pre-tensioned configuration allows grasp forces to be maximal for larger objects and still keeps control components such as tendons out of the grasp workspace. The simplicity of the design lends itself to the possibility of integrated joint angle and surface pressure sensing on the finger itself. The details of design, prototyping and testing are described.

Topics: Design , Robotics , Stiffness
Commentary by Dr. Valentin Fuster
2013;():V06BT07A018. doi:10.1115/DETC2013-13384.

Cardanic motion profiles are a special case of the general epicycloids, hypocycloids, epitrochoids, and hypotrochoids. Under certain geometric constraints, circles, ellipses, and straight lines can be generated. In this paper we explore the use of the geared Cardan mechanism as a component generating metamorphic effects, or equivalent topology changes, in planar linkages by capitalizing on this change from linear to circular motion. The concept of instantaneous Grashof criterion in these mechanisms is also explored. The theory is detailed and example applications are described.

Topics: Linkages
Commentary by Dr. Valentin Fuster
2013;():V06BT07A019. doi:10.1115/DETC2013-13408.

A four-fingered metamorphic robotic hand with a reconfigurable palm is presented in this paper with the application in deboning operation of meat industry. This robotic hand has a reconfigurable palm that generates changeable topology and augments dexterity and versatility for the hand. Mechanical structure and design of the robotic hand are presented and based on mechanism decomposition, kinematics of the metamorphic hand is investigated with closed-form solutions leading to the workspace characterization of the robotic hand. Based on the kinematics of the four-fingered metamorphic hand, utilizing product-of-exponentials formula, grasp map and grasp constraint of the hand are then formulated revealing the grasp robustness and manipulability performed by the metamorphic hand. A prototype of the four-fingered metamorphic hand is consequently fabricated and integrated with low level control and sensor systems leading to a scenario of applying the hand in the field of meat industry for deboning operation.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A020. doi:10.1115/DETC2013-13461.

Advanced robotics requires a new generation of actuators able to exhibit a number of desirable characteristics ranging from high power density and high efficiency, high positioning resolution, high torque capacity and torsional stiffness, lightweight designs and low-cost packages. In this paper, we present the development and the experimental evaluation of a new actuator, aimed at improving the torque density and mechanical efficiency of actuated robotic joints, and enhancing the portability and effectiveness of robotic systems engaged in biomechanical applications such as rehabilitation robots and wearable exoskeletons. The new actuator, called the Gear Bearing Drive (GBD), consists of a two-stage planetary gear arrangement coupled through the planets and driven by an external rotor brushless motor that is inscribed within the input stage sun gear. This planetary configuration enables for incredible high-speed reductions and allows for embedding the motor directly within the gearbox saving significant space on the actuator length. Our initial experimental prototypes have demonstrated impressive performance with the potential to deliver more than 30Nm of continuous torque with 85% mechanical efficiency and 0.0005 degree of backlash, and up to 200 rpm maximum output speed in a highly compact and robust package.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A021. doi:10.1115/DETC2013-13614.

Variable compliance has been a growing topic of interest in legged robotics due to recent studies showing that animals adjust their leg and joint stiffness to adjust their natural dynamics and to accommodate changes in their environment. However, existing designs add significant weight, size, and complexity. Series Elastic Actuators, on the other hand, are designed with a set stiffness usually tuned for actuator performance. We propose a new concept for implementing a physical spring in series with a linear SEA using a cantilevered spring. A movable pivot is used to adjust the stiffness by changing the effective length of the cantilever. While the proposed design does not allow for variable compliance, it does retain many of the benefits of passive spring elements such as absorbing impacts, storing energy, and enabling force control. The primary advantage of the design is the ability to adjust the stiffness of each joint individually without the increased weight and complexity of variable stiffness designs. This paper introduces the motivation for configurable compliance, describes the proposed design concept, explains the design methods, and presents experimental data from a completed prototype.

Topics: Actuators
Commentary by Dr. Valentin Fuster
2013;():V06BT07A022. doi:10.1115/DETC2013-13637.

Series elastic actuators (SEAs) have many benefits for force controlled robotic applications. Placing an elastic member in series with a rigid actuator output enables more-stable force control and the potential for energy storage while sacrificing position control bandwidth. This paper presents the design and measurement error analysis of a low-friction, lightweight linear SEA used in the Shipboard Autonomous Fire Fighting Robot (SAFFiR). The SAFFiR SEA pairs a stand-alone linear actuator with a configurable compliant member. Unlike most electric linear actuators, this actuator does not use a linear guide, which reduces friction and weight. Unlike other SEAs which measure the force by measuring the spring deflection, a tension and compression load cell is integrated into the design for accurate force measurements. The configurable compliant member is a titanium cantilever with manually adjustable length. The final SEA weighs 0.82[kg] with a maximum force of 1,000[N]. The configurable compliant mechanism has in a spring constant range of 145–512[kN/m]. Having no linear guide and incorporating the load cell into the universal joint both introduce measurement errors. The length error across a parallel ankle joint is less than 0.015[mm] and the force measurement error is less than 0.25% of the actual force. Finally, several changes are suggested for the next iteration of the SEA to improve its usability on future robots.

Commentary by Dr. Valentin Fuster

37th Mechanisms and Robotics Conference: Origami-Based Engineering Design

2013;():V06BT07A023. doi:10.1115/DETC2013-12226.

This paper discusses coil structures made from a folded flat sheet which is used for an inductor in high frequency operated battery chargers for future electrified vehicles. For AC loss reduction, a Litz wire is known to be a solution, however, since Litz wires are based on a cable type structure, planar type designs are desired for miniaturization and efficient fabrication of inductors. There exists a paper proposing planar type Litz windings using a printed circuit board for planar inductors. Our unit cell FEM analysis indicates that the stacking effect of multiple winding layers, i.e. the proximity effect between layers, was significant to its overall resistance and therefore the Litz wire pitch has to be much finer than the single board case. Thus, an effective Litz wire design, within our design requirements, requires a very fine strand width that goes beyond the fabrication capability of the vias, i.e. metalized through holes to connect different layers. In this paper, we propose novel planar Litz wire structure without vias by introducing a PCB folding technique by implementing a development chart for a coil structure with twisted strand bundle on one single sheet.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A024. doi:10.1115/DETC2013-12227.

In the context of mechanisms, origami folds can be represented as equivalent mechanisms by taking creases as revolute joints and panels as links. This paper systematically presents various foldable closed-loop linkages extracted from origami folds and origami tessellations. The geometrical characteristics of typical origami crease patterns and patterned assemblies as well as the corresponding equivalent closed-loop linkage are investigated. The basic closed-loop linkages and complicated assemblies are classified according to their mobility in general configuration and the motion characteristics of these origami-enabled linkages are analyzed in terms of screw theory. Based on the geometry and motion analysis, possible simplified mechanisms of each complicated assembly are derived. The existing applications of the origami-inspired foldable closed-loop linkages in packaging and deployable structures, and emergence of new practical use in advanced robotics are addressed.

Topics: Linkages
Commentary by Dr. Valentin Fuster
2013;():V06BT07A025. doi:10.1115/DETC2013-12326.

In this research, we study a method to produce families of origami tessellations from given polyhedral surfaces. The resulting tessellated surfaces generalize the patterns proposed by Ron Resch and allow the construction of an origami tessellation that approximates a given surface. We will achieve these patterns by first constructing an initial configuration of the tessellated surfaces by separating each facets and inserting folded parts between them based on the local configuration. The initial configuration is then modified by solving the vertex coordinates to satisfy geometric constraints of developability, folding angle limitation, and local non-intersection. We propose a novel robust method for avoiding intersections between facets sharing vertices. Such generated polyhedral surfaces are not only applied to folding paper but also sheets of metal that does not allow 180° folding.

Topics: Metals , Construction
Commentary by Dr. Valentin Fuster
2013;():V06BT07A026. doi:10.1115/DETC2013-12343.

This paper investigates the stiffness characteristics of an origami-type carton, which can be modeled into an equivalent mechanism by considering creases as revolute joints and panels as links. Stiffness characteristics of a single crease is investigated regarding its relationships with folding angular velocity and crease length. Based on the kinematic analysis of carton folding, the aggregated stiffness is obtained by integrating the individual crease stiffness into the equivalent mechanism. Finally experiment results of carton folding manipulation are obtained, and comparisons between the mathematical model and experimental data show that the model predicts the carton’s behaviour well.

Topics: Kinematics , Stiffness
Commentary by Dr. Valentin Fuster
2013;():V06BT07A027. doi:10.1115/DETC2013-12348.

The purpose of this work is to create deployment systems with a large ratio of stowed-to-deployed diameter. Deployment from a compact form to a final flat state can be achieved through origami-inspired folding of panels. There are many models capable of this motion when folded in a material with negligible thickness; however, when the application requires the folding of thick, rigid panels, attention must be paid to the effect of material thickness not only on the final folded state, but also during the folding motion (i.e., the panels must not be required to flex to attain the final folded form). The objective is to develop new methods for deployment from a compact folded form to a large circular array (or other final form). This paper describes a mathematical model for modifying the pattern to accommodate material thickness in the context of the design, modeling, and testing of a deployable system inspired by an origami six-sided flasher model. The model is demonstrated in hardware as a 1/20th scale prototype of a deployable solar array for space applications. The resulting prototype has a ratio of stowed-to-deployed diameter of 9.2 (or 1.25 m deployed outer diameter to 0.136 m stowed outer diameter).

Topics: Thickness
Commentary by Dr. Valentin Fuster
2013;():V06BT07A028. doi:10.1115/DETC2013-12405.

The use of origami principles to create 3-dimensional shapes has the potential to revolutionize active material structures and compliant mechanisms. Active origami structures can be applied to a broad range of areas such as reconfigurable aircraft and deployable space structures as well as instruments for minimally invasive surgery. Our current research is focused on dielectric elastomer (DE) and magneto active elastomer (MAE) materials to create multi-field responsive structures. Such multi-field responsive structures will integrate the DE and MAE materials to enable active structures that fold/unfold in different ways in response to electric and/or magnetic field. They can also unfold either as a result of eliminating the applied field or in response to the application of an opposite field. This concept is demonstrated in a folding cube shape and induced locomotion in the MAE material. Two finite element models are developed for both the DE and MAE materials and validated through physical testing of these materials. The models are then integrated to demonstrate multi-field responses of a bi-fold multi-field responsive structure. The bifold model is designed to fold about one axis in an electric field and a perpendicular axis in a magnetic field. Future modeling efforts and research directions are also discussed based on these preliminary results.

Topics: Modeling
Commentary by Dr. Valentin Fuster
2013;():V06BT07A029. doi:10.1115/DETC2013-12497.

Origami is traditionally implemented in paper of homogeneous material properties. This research explores the use of material with embedded electronics such as PCB (Printed Circuit Boards) as the medium for origami folding in order to create an interactive folding experience and to generate foldable objects with added functionalities. PCBs are produced as 2D shapes. By folding PCB arrays it is possible to create 3D objects that contain electronic functions. Conductivity, output devices (such as Light Emitting Diodes) and microcontroller computation can create an interactive folding experience, for user guidance and verification of the folding. We call this approach and methodology PCB Origami. The work presented in this paper describes two unique interaction and fabrication techniques for creating and folding electronic materials. We demonstrate prototypes and present verification/evaluation strategies for guiding the user through the folding process.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A030. doi:10.1115/DETC2013-12584.

An eight bar spatial mechanism inspired from an origami paper fold by considering the carton panels as links and creases as revolute joints is proposed. The constraint deposition and motion characteristics analyses of the eight bar spatial mechanism show that the mechanism implements one screw motion and one pure translation. The configuration space of the mechanism comprises four subspaces. Through adding different geometrical constraints to the eight bar spatial mechanism, different motions of the end-effector are limited leading to three 2-DOF and one 1-DOF motion branches. Additional geometrical constrained conditions in four motion branches with aimed motions of double translations, single translation and two single screw motions are revealed. In the first two motion branches, the eight bar spatial mechanism remains the constant relative orientations of joint-axes. However, the joint-axes of the eight bar spatial mechanism change their orientations in the last two motion branches. Kinematic analyses are discussed in four motion branches, respectively.

Topics: Bifurcation
Commentary by Dr. Valentin Fuster
2013;():V06BT07A031. doi:10.1115/DETC2013-12659.

Origami tessellations consisting of repetitively tiled unit cell elements can be used to manufacture cellular three-dimensional structures with interesting mechanical and other properties. In recent years, the search for alternative and innovative core materials for sandwich constructions has resulted in renewed interest in such foldable structures. The ability to simulate the folding process of such structures with one kinematic degree of freedom is essential for their successful design and manufacture. We present an algorithm that allows for the implicit calculation of arbitrary rigid folding states of quadrilateral-based structures with certain topological features. This enables reliable real-time virtual folding of a large number of important tessellation types which has been put to good use in numerous projects.

Topics: Algorithms
Commentary by Dr. Valentin Fuster
2013;():V06BT07A032. doi:10.1115/DETC2013-12681.

Foldcore sandwich panels have been the focus of much recent study in the aerospace industry. Existing foldcores are composed of a partially folded Miura origami pattern sandwiched between two stiff facings, and have been shown to possess numerous useful properties for impact-resistant applications. Non-Miura origami pattern with similar geometric properties, specifically rigid-foldability and tessellation, may be used as potential alternative origami-cores for sandwich panels, however the mechanical performance of such cores remains an unexplored area. This paper conducts a preliminary investigation into the impact resistance of five non-Miura sandwich panels. The selected patterns are numerically analysed under quasi-static lateral impact loads, and comparisons are drawn with existing foldcore designs. Two particular patterns are found to have failure modes suited for energy-absorbing applications. Prototypes of these two cores are constructed from polypropylene sheet material and experimentally tested to validate numerical results. Reasonable correlation is seen in the force-displacement response of numerical and experimental models.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A033. doi:10.1115/DETC2013-12692.

Origami-based design methods enable complex devices to be fabricated quickly in plane and then folded into their final 3-D shapes. So far, these folded structures have been designed manually. This paper presents a geometric approach to automatic composition of folded surfaces, which will allow existing designs to be combined and complex functionality to be produced with minimal human input. We show that given two surfaces in 3-D and their 2-D unfoldings, a surface consisting of the two originals joined along an arbitrary edge can always be achieved by connecting the two original unfoldings with some additional linking material, and we provide an algorithm to generate this composite unfolding. The algorithm is verified using various surfaces, as well as a walking and gripping robot design.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A034. doi:10.1115/DETC2013-12710.

David A. Huffman (1925–1999) is best known in computer science for his work in information theory, particularly Huffman codes, and best known in origami as a pioneer of curved-crease folding. But during his early paper folding in the 1970s, he designed and folded over a hundred different straight-crease origami tessellations. Unlike most origami tessellations designed in the past twenty years, Huffman’s straight-crease tessellations are mostly three-dimensional, rigidly foldable, and have no locking mechanism. In collaboration with Huffman’s family, our goal is to document all of his designs by reverse-engineering his models into the corresponding crease patterns, or in some cases, matching his models with his sketches of crease patterns. Here we describe several of Huffman’s origami tessellations that are most interesting historically, mathematically, and artistically.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A035. doi:10.1115/DETC2013-12725.

This paper presents a new method using conformal transformation to design crease patterns of circular membranes that can be wrapped up compactly. This method is focused on the advantages of origami that are packaged compactly and deployable at will, and enables to design complex deployable structures systematically and efficiently from simple structures, controlling angles among fold lines. Various deployable circular membranes are successfully produced by the method. They are wrapped up around the center of membranes and form structures such as regular polygons, rectangles, diamond shapes, etc. Circular membranes with zigzag fold lines to radial direction are also demonstrated. They are deployable along radial direction of membranes. The proposed method is flexible to generate zigzag fold lines, compared with the method by mirror image, since zigzag fold lines can be designed close to the center of membranes without geometrical constraints. For industrial application, models made of a plastic film, closing and a stainless steel plate are also demonstrated.

Topics: Design , Membranes
Commentary by Dr. Valentin Fuster
2013;():V06BT07A036. doi:10.1115/DETC2013-12743.

In recent years, as space structures have become large and require higher accuracy, composite honeycombs, which can reduce weight and have low thermal expansion, are in increasing demand. As observed in the design of antenna reflectors and rocket bodies, both flat and 3D-shaped cores are used in this field. However, these special honeycombs have high manufacturing costs and limited applications. This study illustrates a new strategy to fabricate arbitrary cross-section honeycombs with applications of advanced composite materials. These types of honeycombs are usually manufactured from normal flat honeycombs by curving or carving, but the proposed method enables us to construct objective shaped honeycombs directly. The authors first introduce the concept of the kirigami honeycomb, which is made from single flat sheets and has periodical slits resembling origami. In previous studies, honeycombs having various shapes were made using this method, and were realized by only changing folding line diagrams (FLDs). In this study, these 3D kirigami honeycombs are generalized by numerical parameters and fabricated using a newly proposed FLD design method, which enables us to draw the FLD of arbitrary cross-section honeycombs. Next, the authors describe a method of applying this technique to advanced composite materials. Applying the partially soft composite techniques, folding lines are materialized by silicon rubber hinges on carbon fiber reinforced plastic. Complex FLD patterns are then printed using masks on carbon fabrics. Finally, these foldable composites that are cured in corrugated shapes in autoclaves are folded into honeycomb shapes, and some typical samples are shown with their FLDs.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A037. doi:10.1115/DETC2013-12753.

A mechanism that admits continuous free rotation between a fixed platform and a rotating body is described. The mechanism is a serial kinematic chain with several revolute joints. The end of the kinematic chain has free and unlimited rotational motion, equivalent to a standard mechanical pivot, but the travel of each individual joint in the chain is limited to less than ±70 degrees. The joints that compose the chain can thus be constructed using compliant flexure hinges. The entire mechanism can be folded from a single flat sheet of material, and is thus well suited for self-assembly by folding, which is an increasingly attractive technique for building micro-scale devices. Potential applications include rotating propellers for micro underwater or fluid-immersed (e.g. within a blood vessel) robots, and high-mobility wheel-legs for crawling vehicles.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A038. doi:10.1115/DETC2013-12901.

Traditionally, origami-based structures are designed on the premise of “rigid folding,” meaning that the facets and fold lines of origami can be replaced with rigid panels and ideal hinges, respectively. Rigid folding is an important factor in defining origami for mathematicians and geometricians. However, ideal rigid folding is impossible in real structures and every act of folding and unfolding is accompanied by elastic deformations. In this study, we focus on these elastic deformations in order to expand origami into a new method of designing morphing structures. We start by proposing a simple model for evaluating elastic deformation in nonrigid origami structures. In this model, the facets of origami are replaced with plates that are not only rigid but also elastic. This partially elastic origami model has a one-degree-of-freedom mechanism; therefore, its folding process can be described using rigid folding simulation techniques. In this process, the deformations of the elastic plates can be calculated and we can estimate the elastic energy through folding/unfolding. We then apply these methods to deployable plate models constructed of quadrilateral plates and hinges to design new deployable structures. Initial strain is introduced into the elastic parts of the partially elastic origami model and these parts function as actuators for deployment. Then, by using the finite element method, we conduct numerical simulations and confirm the deploying capabilities of the models.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A039. doi:10.1115/DETC2013-12947.

Because of the internal mobility, rigid origami structures have great potential in engineering applications. In this research, a kinematic model of the rigid origami pattern is proposed based on the assembly of spherical 4R linkages. To ensure the rigid origami pattern with mobility one, the kinematic and geometric compatibility conditions of the kinematic model are derived. Four types of flat rigid origami patterns are obtained, including three existing types as well as a novel one called the supplementary type. To testify and display the mobile processes of the patterns, their simulation models are built accordingly.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A040. doi:10.1115/DETC2013-13016.

In this paper, we present a deformable wheel robot using the ball-shaped waterbomb origami pattern, so-called magic-ball pattern. The magic-ball origami pattern is a well-known pattern that changes its shape from a long cylindrical tube to a flat circular tube. By using this special structure, a wheel with mechanical functionalities can be achieved without using many mechanical parts. Moreover, because of the characteristic that the structure constrains its own movement, it is possible to control the whole shape of the wheel using only few actuators. And also, from analysis of the wheel structure in kinematic model, the performance of the wheel and determine the condition for actuators can be predicted. We think that the proposed design for the deformable wheel shows the possibility of using origami structure as a functional structure with its own mechanism.

Topics: Robots , Wheels
Commentary by Dr. Valentin Fuster
2013;():V06BT07A041. doi:10.1115/DETC2013-13231.

Origami is a traditional Asian fine art of creating three-dimensional structures by folding paper. Recently, engineers have started to exploit the functional advantages of foldable structures. Formal representations of origami structures are limited. Most of the origami research describes an origami structure by providing the geometric properties of creases and vertices. This paper proposes a novel representation of an origami structure by describing the faces. An origami sheet is first pixelated with evenly distributed cellular agents, referred to as cells. Pixelization makes the origami structurally analogous to an LED matrix screen, with each of the cells being one LED pixel on the screen. Every cell will possess two key properties that contribute to determine the entire pattern: the cell type, which is analogous to the color of the LED; and the cell size, which is analogous to the light intensity of the LED. Therefore, a collection of cells with the same cell type (color) could represent the rough profile of an origami face, while the sizes of the cells are used to determine the face borders.. Creases and vertices can be subsequently determined by attaining the precise borders among faces. In this paper, we will also propose a crease restoration algorithm to determine the face borders and creases that then enable a fold to the final origami shape. The novel pixelated multicellular representation of origami enables new computational origami design methods as well as new self-folding origami structures.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A042. doi:10.1115/DETC2013-13324.

Foldcores are folded open cellular structures which are currently under development at Institute of Aircraft Design (IFB). The IFB has generated an integrated manufacturing process to produce foldcores, starting with the mathematical methods to design the required foldcore geometry to the point of realizing them in an automated and continuous fashion. By isometric folding of planar base materials foldcores can and have already been manufactured out of a large variety of materials: cardboard, papers, metals (aluminum, steel, titanium), different thermoplastic films (PC, PVC, PPSU, PEEK) as well as advanced fibre reinforced materials (glass, carbon, aramid fibres).

For the technical use of foldcores in sandwich structures it is necessary to supply a competitive level of mechanical performance. We discuss the mechanical properties of foldcores compared to other state of the art core materials. We detail the testing methods used to determine compression and shear strengths and stiffnesses, which are based upon international standards. Evaluation of the test results show potential for the use of foldcores in high performance lightweight structures, especially considering their unique multifunctional applicability.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A043. doi:10.1115/DETC2013-13378.

Radio communications apertures for spacecraft have long been implemented using deployable architectures in order to fit within the allowable launch vehicle volume. Apertures for optics missions have traditionally not been segmented because of the tight requirements on the deployed surface. By the nature of the problem, larger apertures are generally better, but complicate orbital delivery. While there are several reflectors commercially available, high packing ratios come at very high cost due to the extremely complex nature of the designs. Researchers at the Space Vehicles Directorate have been investigating ways to enable high packing ratios while reducing the design, integration, and testing complexity of deployable systems, thereby driving down cost and enabling greater mission capabilities. Recent advances in flexible composites have opened up the possibilities of packaging apertures using either distributed or concentrated strain. This paper offers an overview of recent work done to enable lower complexity deployable apertures. Several origami-inspired designs are presented including a flat spiral folding membrane, a parabolic antenna reflector, and a phased array structure.

Topics: Space vehicles
Commentary by Dr. Valentin Fuster
2013;():V06BT07A044. doi:10.1115/DETC2013-13407.

Action origami is a field of origami dealing with models that are folded so that in their final, deployed state they exhibit motion. Hundreds of action origami models exist, many of which use complicated kinematics to achieve motion in their deployed state. Understanding the kinematics of action origami could result in a new source of concepts for deployable, movable engineering solutions. This paper presents an approach for evaluating and classifying the mechanisms that enable action origami motion. Approximately 300 action origami models are studied. Although disguised with artistic elements, it is found that most action origami models are based on a few fundamental mechanisms. A classification scheme is proposed, and a previously unused class of action origami is identified as an area for future origami art.

Topics: Kinematics
Commentary by Dr. Valentin Fuster
2013;():V06BT07A045. doi:10.1115/DETC2013-13439.

Origami engineering — the practice of creating useful three-dimensional structures through folding operations on two-dimensional building-blocks — is receiving increased attention from the science, mathematics, and engineering communities. The topic of this paper is a new concept for a self-folding material system. It consists of an active, self-morphing laminate that includes two meshes of thermally-actuated shape memory alloy (SMA) separated by a compliant passive layer. The goal of this paper is to analyze several of the key engineering tradeoffs associated with the proposed self-folding material system. In particular, we examine how key design variables affect folding behavior in an SMA mesh-based folding sheet. The design parameters we consider in this study are wire thickness, mesh wire spacing, thickness of the insulating elastomer layer, and heating power. The output parameters are maximum von Mises stress in the SMA, maximum temperature in the SMA, and minimum folding angle. The results show that maximum temperature in the SMA is mostly dependent on the total heating power per unit width of SMA. The results also indicate that through-heating — heat transfer from one SMA layer to the other through the insulating elastomer — can impede folding for some physical configurations. However, we also find that one can mitigate this effect using a staggered mesh configuration in which the SMA wires on different layers are not aligned. Based on our results, we conclude that the new staggered mesh design can be effective in preventing unintended transformation of the non-actuated layer.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A046. doi:10.1115/DETC2013-13477.

This paper describes “digital origami” from geometrically frustrated tiles: arrays of structures that cannot attain an energetically favorable flat state because of internal constraints. Each tile can typically snap between two symmetric energy-minimizing states, and neighboring tiles are coupled so that a collection of binary tile states determines the local curvature of the entire sheet. Modular structures like these tiles give great advantages in manufacturing and in predictive simulation, and their discrete nature is a good match for digital readout and control of self-folding systems.

The digital origami concept applies to materials from the nanoscale to the macroscale. An example from previous researchers is a metal sheet with an array of dimples that can flex up or down. In this paper we investigate more general techniques that can develop planar sheets into bistable structures. Such methods include installing compressed pieces into a flat sheet of material, or tying together parts of a sheet (smocking). These methods work with a large variety of technologically important materials including circuit boards and semiconductor substrates.

While there are clear benefits to such structures, significant obstacles to design exist in manufacturing, in evaluating their mechanical properties, and in choosing the best arrangement of tile states to match a desired shape. Determining the optimal flipping order of tile states to change the sheet from one shape to another is a sequencing problem analogous to protein folding, and origami from non-planar surfaces is a little-explored area in the fine arts. The paper discusses algorithms for curve-matching with one-dimensional arrays by error diffusion, and shape prediction for two-dimensional sheets with pre-programmed tile states. Low computational cost is required for creating structures that can predict, detect, and even change their own three-dimensional shapes using low-power onboard microprocessors. Motivators for this challenge include shape measurement over a large size range — for example, detecting the changing shapes of biological microstructures or endowing robots with a spatial sense similar to human proprioception — and self-modeling of structural properties for lightweight morphing structures that can strengthen for impact in a given direction using a limited amount of material.

Topics: Tiles
Commentary by Dr. Valentin Fuster
2013;():V06BT07A047. doi:10.1115/DETC2013-13490.

Some attempts to get efficient membrane space structure designs using various conceptual origami models are introduced, and their basic design considerations to fit their concepts to actual space structural hardware are presented. They cover cylindrical shell elements with axially buckled patterns for inflatable tubes, and deployable flat membrane structures for light weight large aperture spacecraft including their thickness effects and their various variations driven from geometrical dual properties. Some examples of deployable concepts in nature with reference to better designs of membrane space structures are also shown, and some limitations of their origami models are discussed.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A048. doi:10.1115/DETC2013-13495.

Crash boxes in automobiles are often made from thin-walled tubes. They are designed to absorb energy when subjected to axial crushing. In this paper we present a novel crash box known as the origami crash box. It is produced by pre-folding the surface of a thin-walled tube according to a developable origami pattern. The pre-folded surface serves both as a type of geometric imperfection to lower the initial peak force, and as a mode inducer to trigger a collapse mode that is more efficient in terms of energy absorption. Numerical simulation of quasi-static axial crushing of the origami crash box has shown that a new collapse mode deemed the completed diamond mode can be triggered in tubes with square, rectangular, and polygonal cross sections and tapered shapes, leading to both a substantial gain in overall energy absorption, while at the same time, a reduction in initial peak force.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A049. doi:10.1115/DETC2013-13553.

To realize engineered materials and structures via origami methods and other folding construction techniques, fundamental understanding of paper folding mechanics and their dependency on paper micro/nanostructure is needed. Using selected papers commonly used in origami designs, we establish the relationship between the mechanical properties of fibrous paper and their corresponding ability to form and retain simple creases and mountain/valley folds. Using natural fiber paper (abaca), synthetic fiber paper (Tyvek), and a metal-fiber laminate paper, we studied how the fold radius depends on the load applied using a controlled rolling apparatus. After folding, we examined the resultant micro- and nanoscale deformation using electron microscopy. In general we found that the fold radius follows a power law, decreasing with the applied rolling force. At a critical strain, each paper exhibits a transition between elastic and plastic behavior, after which the trend asymptotically approaches the minimum fold radius with increased applied force. Finally, we present examples of centimeter-scale two-dimensionally “mountain fold” patterns and relate the folding characteristics observed in these designs to the mechanical properties of the papers in folding.

Commentary by Dr. Valentin Fuster

37th Mechanisms and Robotics Conference: Robot Kinematics and Motion Planning

2013;():V06BT07A050. doi:10.1115/DETC2013-12044.

In a previous paper, this author proposed a novel type of underactuated parallel wrist (PW) with a single-loop architecture containing only one nonholonomic constraint. Moreover, he addressed its position analysis and path planning and showed that closed-form formulas can be used to solve all the finite-kinematics problems involved in the path planning of the novel PW. Here, the instantaneous kinematics and the singularity analysis of this PW are addressed. In particular, both the analytic and geometric conditions which identify the singular configurations are presented together with their static interpretation. The presented results are relevant for designing this type of PWs.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A051. doi:10.1115/DETC2013-12285.

Turning a robot, particularly an under-actuated bipedal humanoid robot, is challenging. Several methods proposed in the literature for producing human-like motion in such robots are innovative but are limited in their range of motion. This paper presents an approach to control the orientation of a robot using a control moment gyroscope (CMG). A demonstration platform is developed to test this concept and physical experiments are conducted to determine the prototype’s turning range and performance. This concept is then extended to a backpack mount where trials are conducted using human subjects to estimate the performance of the system that can potentially be used to turn bipedal humanoid robots.

Topics: Robots
Commentary by Dr. Valentin Fuster
2013;():V06BT07A052. doi:10.1115/DETC2013-12445.

Mechanisms with reconfigurability have become a trend in development of multi-functional robots which can adapt to unexpected environments and perform complicated tasks. This paper presents a novel metamorphic parallel manipulator with the ability to change its mobility through the phase change of a variable-axis (vA) joint integrated in each limb. The platform has 6 DOFs in the source phase and can reconfigure its mobility to 5, 4 and 3 resorting to redundant actuation. This leads to reconfigurability and multi-functionality of the parallel manipulator characterized by the mobility configuration variation. A control strategy and a trajectory planning algorithm for reconfiguring the mobility configuration of the manipulator are proposed and simulations are carried out to identify a proper way of reconfiguration.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A053. doi:10.1115/DETC2013-12498.

In this paper, kinematic analysis and motion planning of a quadruped robot are presented by regarding the robot as an equivalent parallel platform-type mechanism with RRRS limb structure. Based on screw theory, the mobility of the quadruped robot with different touchdown legs is analyzed, and proves that the design for degree of freedom (DOF) is available. Base on the established kinematic model of a single leg in terms of POE formula of screw theory, several typical patterns of walking motion planning are implemented and verified by the ADAMS-based simulation. In order to show a good maneuverability and potential manipulation capability of the quadruped robot as a parallel manipulator, the gait planning reflecting two rotating motion patterns (including the rotating motion and walking motion) is modeled and simulated by kinematics of the equivalent parallel manipulators. Finally, a prototype of the quadruped robot has been built. Experimental test shows the practical walking and rotating ability as desired.

Topics: Kinematics , Robots
Commentary by Dr. Valentin Fuster
2013;():V06BT07A054. doi:10.1115/DETC2013-12590.

This paper presents the design of our new 33 degree of freedom full size humanoid robot, SAFFiR (Shipboard Autonomous Fire Fighting Robot). The goal of this research project is to realize a high performance mixed force and position controlled robot with parallel actuation. The robot has two 6 DOF legs and arms, a waist, neck, and 3 DOF hands/fingers. The design is characterized by a central lightweight skeleton actuated with modular ballscrew driven force controllable linear actuators arranged in a parallel fashion around the joints. Sensory feedback on board the robot includes an inertial measurement unit, force and position output of each actuator, as well as 6 axis force/torque measurements from the feet. The lower body of the robot has been fabricated and a rudimentary walking algorithm implemented while the upper body fabrication is completed. Preliminary walking experiments show that parallel actuation successfully minimizes the loads through individual actuators.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A055. doi:10.1115/DETC2013-12873.

A quadruped robot named “Baby Elephant” with parallel legs has been developed. It is about 1 m tall, 1.2 m long and 0.5m wide. It weighs about 130 kg. Driven by a new type of hydraulic actuating system, the Baby Elephant is designed to work as a mechanical carrier. It can carry a payload no less than 50 kg. Operating outdoors using wireless remote control, the robot will be able to traverse uneven terrain applying walking and trotting gaits and can walk up and down 10 degree inclines. The Baby Elephant carries a lithium battery fixed at the belly to supply all the power. This paper describes the structure of the legs and the application of the energy saving mechanisms on the leg. Simulations and experiments are carried out to testify the efficiency of the spring system in terms of energy saving.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A056. doi:10.1115/DETC2013-13034.

The Mars Science Laboratory (MSL) Curiosity Rover is currently exploring the surface of Mars with a suite of tools and instruments mounted to the end of a five degree-of-freedom robotic arm. To verify and meet a set of end-to-end system level accuracy requirements, a detailed positioning uncertainty model of the arm was developed and exercised over the arm operational workspace. Error sources at each link in the arm kinematic chain were estimated and their effects propagated to the tool frames. A rigorous test and measurement program was developed and implemented to collect data to characterize and calibrate the kinematic and stiffness parameters of the arm. Numerous absolute and relative accuracy and repeatability requirements were validated with a combination of analysis and test data extrapolated to the Mars gravity and thermal environment. Initial results of arm accuracy and repeatability on Mars demonstrate the effectiveness of the modeling and test program as the rover continues to explore the foothills of Mount Sharp.

Topics: Robotics
Commentary by Dr. Valentin Fuster
2013;():V06BT07A057. doi:10.1115/DETC2013-13197.

This paper studies the rigid body guidance problem for 3-DOF planar parallel manipulators (PPM) with three-triad assembly. We present a novel, unified, and simultaneous type and dimensional synthesis approach to planar parallel manipulator synthesis by using kinematic mapping, surface fitting, and least squares techniques. Novelty of our approach lies in linearization of a highly non-linear problem and the fact that the nature of the given motion or displacement drives the synthesis process without assuming triad topology or their geometry. It has been well established that by using planar quaternions and kinematic mapping, workspace related constraints of planar dyads or triads can be represented as algebraic constraint manifolds in the image space of planar displacements. The constraints associated with planar RR-, PR- and RP-dyads correspond to a single quadric in the image space, while that of each of the six planar triads (RRR, RPR, PRR, PPR, RRP and RPP) map to a pair of quadrics and the space between them. Moreover, the quadrics associated with RRR- and RPR-triads are of the same type as that of RR dyads, of PRR- and PPR-triads as that of PR-, and RRP- and RPP-triads as that of RP-dyad. This simplification nicely extends a dyad synthesis problem to a triad synthesis one. The problem is formulated as the least-squares error minimization problem to find a trinity of quadrics that best fit the image points of task displacements. The fitting error corresponding to each single quadric of the trinity is regarded as variation (thickness) of that quadric, which turns that quadric into a pair of quadrics. Hence, three dyads with minimal surface fitting errors can be converted to three triads in the Cartesian space.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A058. doi:10.1115/DETC2013-13475.

This paper introduces a strategy to accomplish pick-and-place operations for a six-degrees-of-freedom (6-DOF) robotic arm attached to a wheeled mobile robot. This research work is part of a bigger project in developing a robotic-assisted nursing to be used in medical settings. The significance of this project relies on the increasing demand for elderly and disabled skilled care assistance which nowadays has become insufficient. Several methods were implemented to make a 6-DOF manipulator capable of performing pick-and-place operations. This paper presents an approach for solving the inverse kinematics problem and planning collision-free paths. An Iterative Inverse Kinematics method (IIK) was introduced to find multiple configurations for the manipulator along a given path. The IIK method takes advantage of a specific geometric characteristic of the manipulator, in which several joints share a common plane. Ten different scenarios with different number and pattern of obstacles were used to verify the efficiency of a path planning algorithm introduced here. Other methods, also implemented in the current project, which describe the manipulator and its capabilities, are presented elsewhere [1]. Overall results confirmed the efficiency of the implemented methods for performing pick-and-place operations for a 6-DOF manipulator.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A059. doi:10.1115/DETC2013-13587.

Robotic manipulators can be categorized as either parallel, serial, or in some cases a combination of the two. Among others, a notable drawback of serial manipulators in dynamic applications is the large inertia created by typically heavy electromechanical actuators at the distal end of the manipulator. In addition, compact packaging of multiple actuators in a multi-degree of freedom (DOF) joint, as is often necessary with serial manipulators, can be difficult. These difficulties can be alleviated should a means be found to relocate actuators across one or more degrees of freedom. In this paper, we investigate a constant velocity (CV) linkage, the Clemen’s linkage, that may be used to relocate an actuator across a one DOF revolute joint to an adjacent link while maintaining a serially actuated architecture. This can be very advantageous in some applications such as a humanoid robot ankle. The linkage is analyzed for both its range of motion and torque capacity for such applications given limitations of currently available bearing hardware.

Topics: Linkages , Robotics , Statics
Commentary by Dr. Valentin Fuster

37th Mechanisms and Robotics Conference: Robot/Machine Dynamics and Control

2013;():V06BT07A060. doi:10.1115/DETC2013-12103.

Parallel robots have proved they can have better performances than serial ones in term of rigidity and payload-to-weight ratio. Nevertheless their workspace is largely reduced by the presence of singularities. In particular, the Type 2 singularities (parallel singularities) separate the workspace in different aspects, corresponding to one (or more) robot assembly modes. In order to enlarge the workspace size, it has been proved that a mechanism can cross the singularity loci by using an optimal motion planning. However, if the trajectory is not robust to modeling errors, the robot can stop in the singularity and stay blocked.

Therefore, the objective of this paper is to show new general procedure that allows the exit of a parallel manipulator from a Type 2 singularity. Two strategies are presented. The first one proposes the computation of an optimal trajectory that makes it possible for the robot to exit the singularity. This trajectory must respect a criterion that ensures the consistency of the robot dynamic model all along the singularity loci. The second trajectory consists in declutching one of the robot actuator in order to change the kinematic and dynamic behavior of the mechanism so that no singularity exists anymore. Theoretical works are illustrated, discussed and analysed through simulations achieved on a planar five-bar mechanism.

Topics: Manipulators
Commentary by Dr. Valentin Fuster
2013;():V06BT07A061. doi:10.1115/DETC2013-12160.

Static grasping of a spherical object by two robot fingers is studied in this paper. The fingers may be rigid bodies or elastic beams, they may grasp the body with various orientation angles, and the tightening displacements may be linear or angular. Closed-form solutions for normal and tangential contact forces due to tightening displacements are obtained by solving compatibility equations, force-displacement relations based on Hertz contact theory, and equations of equilibrium. Solutions show that relations between contact forces and tightening displacements depend upon the orientation of the fingers, the elastic constants of the materials, and area moments of inertia of the beams.

Topics: Robots , Grasping
Commentary by Dr. Valentin Fuster
2013;():V06BT07A062. doi:10.1115/DETC2013-12407.

Joint torque feedback is useful in serial manipulator control algorithms for contact control, collision detection, performance analysis, etc. For example, the predicted torque can be compared to the measured torque so the system can respond to unexpected or unmodeled physical inputs. The input current to the joint motors can be used to estimate the input torque if the motor parameters are well-understood. However, in a closed commercial system, the motor parameters are often proprietary or unknown. Also, systems that sense or estimate motor torques instead of the joint torques require compensation for gear train losses.

In this work, we propose a method for mapping the measured motor current to the joint torque on a serial manipulator without joint torque sensors, thus advancing the potential to implement torque feedback algorithms such as collision detection on any industrial robot with joint position and motor current feedback. This new torque estimating technique (as opposed to using Newton-Euler dynamics) allows for sensing of external forces in collision detection applications for a position controlled robot.

The method requires knowledge of the robot link centers of mass, masses, and inertias and that the motor currents and joint positions can be measured. The joint torques due to gravity, inertia, and Coriolis are estimated by the Newton-Euler method using the system geometry, link masses, and the measured joint positions. A method for estimating friction losses using only the current and the predicted joint torque is demonstrated. The measured current, less estimated friction, is then mapped to the joint torque.

The validity of the black box joint torque estimating model was demonstrated using two Motoman SIA-5D manipulators with a 3rd party controller provided by Agile Planet. The joints of the robot were moved through a variety of test motions with known joint torque characteristics (as calculated using Newton-Euler dynamics). Estimated joint torques are similar to the calculated torque. Physical significance of the torque is validated by comparing the estimated torque to the calculated torque generated by a known force. The feasibility of the estimated torque error to force detection is discussed in terms of improving the safety and deployment options for industrial robotic systems.

Topics: Torque , Manipulators
Commentary by Dr. Valentin Fuster
2013;():V06BT07A063. doi:10.1115/DETC2013-12781.

In this paper, a new kind of 6-legged robot for drilling holes on the aircraft surface is presented. Each leg of the robot is a parallel mechanism with 3 degree of freedoms thus the robot includes totally 18 motors. Due to different work status, the control modes of these motors are also different and thus the force-position hybrid control method is applied. The kinematic and dynamic model is briefly introduced. Then the robot gait is discussed. After that hybrid control method is introduced: first the control mode of each motor should be determined, then the position or force control curves should be calculated. In the end of this paper, both virtual and real prototype of this robot is showed and the experiment result showed that the hybrid control method can significantly improve the robot performance.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A064. doi:10.1115/DETC2013-12991.

This paper presents the topology variation of a 3(rT)PS metamorphic parallel mechanism which can change its mobility from 3 to 6. The reconfiguration stems from a reconfigurable (rT)PS limb of which the two phases can be unified by taking one as a special case of the other. Based on this, unified inverse kinematics is solved and a unified dynamics modeling is built using screw theory which naturally represents the geometric constraint and actuation forces in the same manner. The obtained modeling covers all the topologies of the parallel mechanism. A numerical example demonstrates the theoretical results which provide basis for this metamorphic parallel robot with applications in reconfiguration-required environment.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A065. doi:10.1115/DETC2013-13121.

This paper presents a grid-based scan-to-map matching technique for accurate simultaneous localization and mapping (SLAM). At every acquisition of a new scan, the proposed technique estimates the relative position from which the previous scan was taken, and further corrects its estimation error by matching the new scan to the globally defined map. In order to achieve best scan-to-map matching at each acquisition, the map to match is represented as a grid map with multiple normal distributions (NDs) in each cell. Additionally, the new scan is also represented by NDs, developing a novel ND-to-ND matching technique. The ND-to-ND matching technique has significant potential in the enhancement of the global matching as well as the computational efficiency. Experimental results first show that the proposed technique successfully matches new scans to the map generating very small position and orientation errors, and then demonstrates the effectiveness of the multi-ND representation in comparison to the single-ND representation.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A066. doi:10.1115/DETC2013-13431.

We consider the use of autonomous boats for oil skimming and clean up of surface debris by operating two boats with a boom cooperatively. A boom, or a cable as considered in this paper, attached to two robots at each end can be used to efficiently manipulate multiple objects on the surface of the water. In our previous work, Bhattacharya, et al. (ICRA 2011), we showed the feasibility of this concept with an experimental testbed using two autonomous boats and a towed cable. This work showed that an accurate dynamic simulation of the system is indispensable in analysis and development of efficient control schemes. For the purpose of manipulating objects in such a way, not only do we need to model the drag forces, but we also need to model the interaction between the cable and the objects. In this paper we model the boom or the cable as a chain with a discrete number of rigid links connected by passive revolute joints and model the interaction of the cable with the water (drag) as well as the contacts with objects on the surfaces. We derive the equations governing the cable and object dynamics and model the contact interactions as linear complementarity constraints. The boats are driven by simple controllers that only require knowledge of positions and velocities at the both ends of the cable. Several examples are used to illustrate the performance of the numerical simulation.

Topics: Simulation , Boats
Commentary by Dr. Valentin Fuster
2013;():V06BT07A067. doi:10.1115/DETC2013-13516.

Hip torque and radial forcing along the leg are two common actuation methods for legged robots. However, hip torque and radial forcing have not been compared as potential alternative strategies of actuation. The respective advantages and disadvantages of hip torque and radial forcing are not well known. In this paper, we compare hip torque and radial forcing actuation through the simulation of two models: a Rotary-forced Spring-Loaded Inverted Pendulum and a Radially Forced Spring-Loaded Inverted Pendulum. Both actuation methods can produce fully asymptotically stable locomotion. Interestingly, it is found that they improve locomotion stability in different ways: hip torque first destabilizes locomotion when initially introduced but greatly stabilizes locomotion when it keeps increasing; radial forcing always stabilizes locomotion, but in a moderate way.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A068. doi:10.1115/DETC2013-13599.

This paper presents a study of the dynamic response of actuation devices used in mechanical systems with nonlinear dynamics such as robot manipulators. The study shows that the actuation forces/torques provided by actuation devices can be divided into two basic groups. The first group corresponds to the components of each actuator force/torque that is “actuator motion independent”. The dynamic response of this group is relatively high and limited only by the dynamic response limitations — for the case of electrically driven actuation systems — of the driving power amplifiers, electronics, computational and signal processing devices and components. The second group corresponds to those components of the actuator forces/torques that is “actuator motion dependent”. The dynamic response of this group is relatively low and dependent on the actuator effective inertial load and actuation speed. In all mechanical systems that are properly designed, the dynamic response of the first group is significantly higher than those of the second group. By separating the required actuating forces/torques into the above two groups, the dynamic response of such nonlinear dynamics systems may be determined for a given synthesized trajectory. The information can also be used to significantly increase the performance of control systems of such mechanical systems. When a feed-forward control signal is used, the performance of the system is shown to be significantly improved by generating each one of the group of components separately considering the dynamic response of the actuation system to each one of the groups of components. An example and practical methods of implementing the proposed feed-forward control for nonlinear dynamics systems are provided.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A069. doi:10.1115/DETC2013-13605.

In this paper, a new method is presented for model parameter identification of a large class of nonlinear dynamics systems that are not fully controlled. The method uses trajectory patterns with feed-forward controls to identify model parameters of the system. The developed method ensures full system stability, does not require close initial estimated values for the parameters to be identified, and provides a systematic method of emphasizing on the estimation of the parameters associated with lower order terms of the system dynamics model and gradually upgrading the accuracy with which the model parameters, particularly those associated with the higher order terms of the system dynamics, are estimated. The developed method is based on Trajectory Pattern Method (TPM). The mathematical proof of convergence of the developed method and results of its implementation on a typical system with highly non-linear dynamics are provided.

Commentary by Dr. Valentin Fuster

37th Mechanisms and Robotics Conference: Theoretical and Computational Kinematics (A.T. Yang Symposium)

2013;():V06BT07A070. doi:10.1115/DETC2013-12110.

This research investigates analytical analysis and synthesis problems of force-input and coupler-driven four-bar linkages. Very little bibliography can be found of this type of mechanism in contrast to the conventional torque-input crank-driven four-bars. Traditional four-bar mechanisms use the adjacent links jointed to the ground as input/output links; whereas a coupler-driven four-bar mechanism is actuated by applying the force or torque directly to the coupler link, the member has no direct connection to the base. In this paper, the transmission performance indices, TI (Transmissibility Index) and MI (Manipulability Index) are reviewed, Collinearity Points are defined, where both the MI and TI are unity and therefore the optimal motion transmission performance can be achieved. The Collinearity Circle, which is the locus of all Collinearity Points, is proposed, a novel performance indicator which is used to monitor the effectiveness of the transmission in a force-input coupler-driven four-bar. The beauty of this Collinearity Circle lies not only in its convenient shape, which is a circle, but also in its derivation that can be shown to be merely geometry-dependent. Just like the famous Instant Center, which is also only geometry-dependent, this new Collinearity Circle will prove to be a handy addition to the kinematics toolbox for its power to enable speedy construction and ballpark estimations on the transmission properties of force-input coupler-driven mechanisms. Observations and applications are presented.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A071. doi:10.1115/DETC2013-12555.

Baranov truss is a structural framework composed of revolute jointed bars. It is also regarded as an Assur kinematic chain (briefly termed AKC) in viewpoint of kinematics. Based on Grübler mobility criterion, these AKCs with zero DoF should be generally unmovable. However, under some specified dimensional constraints, they have the constrained motion. In the paper, we focus on identifying mobility constraints of the simplified planar 7-bar Type-I Baranov-truss (AKC-I) linkage and on synthesizing one novel family of movable focal-type 7-bar linkages. In the beginning, applying the vector-loop approach produces the algebraic relations between structural parameters and angular variables of the simplified 7-bar such linkages. Next, by Sylvester elimination method, we attain one algebraic polynomial, which is function of an input variable only, and propose the mobility dimensional constraints of such truss architecture. Moreover, following the graphical technique for generating Kempe focal linkages, we systematically synthesize eight kinds of new movable focal-type 7-bar Baranov-truss linkages by removing one specified redundant link. These synthesized linkages further confirm the accuracy and availability of the derived mobility dimensional constraints.

Commentary by Dr. Valentin Fuster
2013;():V06BT07A072. doi:10.1115/DETC2013-12836.

A central element in the kinematic analysis is the determination of partial derivatives of the twist of a member in a serial kinematic chain with respect to the joint parameters (angles, translations). This requires partial derivatives of the screw system, generated by a given ordered set of joint screws. While the closed form expression of first and second order derivatives are widely known in terms of screw products, and even the derivatives up to fifth order have been reported, a general closed form expression for derivatives of arbitrary order remained an open issue. Such a closed form expression of partial derivatives of the joint screws for any order is reported in this paper. The final result for the n-th partial derivative involves n-fold nested Lie bracket (screw products) of the joint screws. The crucial observation that gives rise to the closed form expression is that the derivative is given as a sum of terms with complementary joint index ranges.

Topics: Screws
Commentary by Dr. Valentin Fuster
2013;():V06BT07A073. doi:10.1115/DETC2013-13364.

Structural mobility criteria, such as the well-known Chebychev-Kutzbach-Grübler (CKG) formula, give the correct generic mobility of a linkage (possibly of a certain class, e.g. planar, spherical, spatial) provided that it is not topologically overconstrained. As a matter of fact all known structural mobility criteria are prone to topological redundancies.

In this paper a combinatorial algorithm is introduced that determines the correct generic/topological mobility of any planar and spherical mechanism. The algorithm also yields a set of independent links that can be used as input, as well as the redundantly constrained sub-linkages. A mathematical proof of the algorithm and the underlying mathematical concept is presented. The proposed method relies on an established algorithm developed within combinatorial rigidity theory, called pebble game, originally developed for checking the rigidity/immobility of constraint graphs. A novel theorem is introduced and later proved in the paper which in turn enables applying the algorithm to any holonomic planar or spherical mechanism with higher and lower kinematic pairs and multiple joints. A further important result of applying this algorithm is that it gives rise to a decomposition into Assur graphs, which is briefly discussed in this paper.

Topics: Algorithms
Commentary by Dr. Valentin Fuster

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In