bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Analysis of Soft Pneumatic Sleeve for Arm Orthosis
Authors: Singh Gaurav , Xiao Chenzhang , Krishnan Girish , Hsiao-Wecksler Elizabeth
Published: December 2016

Patients that use crutches for ambulation experience forces as high as 50% of body weight and extreme extension angles at the wrist, which increases the risk of joint injury such as carpal tunnel syndrome. We have designed and fabricated a soft pneumatic sleeve to reduce the wrist loading by transferring part of the load to the forearm. The sleeve uses a Fiber Reinforced Elastomeric Enclosure (FREE). FREEs are soft pneumatic actuators that can generate force and moment upon inflation. We have used a contracting FREE, which is wrapped in a helical shape around the forearm as part of the sleeve. Upon actuation, it contracts in length and reduces in diameter, thereby generating a constricting force around the forearm.

In this paper, we describe the modeling of the constricting force generated by the helical FREE. We can model the FREE as a string due to its negligible bending stiffness. The constriction force can be expressed in terms of the axial tensile force generated in the FREE upon actuation and the geometry of the helix. To obtain the axial force, we have used a model previously reported in literature that uses a constrained volume maximization formulation. We validate the string model by comparing with experimental results.
Improved User Experience in a VR Based Design Review
Authors: Steger Wolfgang , Kim Tae-Soo , Gebert Martin , Stelzer Ralph
Published: December 2016

Observations of design review sequences by means of Virtual Reality (VR) and participant interviews have demonstrated that improvements may be made through providing selected user functions to participants who would otherwise just be observers. These functions are found from a survey of more or less experienced VR users in design reviews. The basic idea is that the participants are given access to special review data via App and smart device and are thus capable of immediately controlling the view of the product under review. Thus, for instance, the participants are able to download the structure tree including the components of the product to be tested onto their devices, navigate inside the structure tree, and get information about component parameters independently of the other participants.

Participants can also configure the representation of the VR model displayed for all participants via smart device (highlighting, visibility, colour, ...) and set up the view. This makes communication easier, since otherwise the respective settings have to be administered by a VR operator. Special user interaction functions may improve the control of design reviews by changing the participants’ role from passive to active.

A special requirement is the spatial selection of model components in the stereoscopic VR view. To meet this demand a Leap Motion controller transmits position data from the users hand to the pointer of the VR System via the protocol Virtual Reality Peripheral Network (VRPN).
Design and Fabrication of Hierarchical Multi-Stable Structures Through Multi-Material Additive Manufacturing
Authors: Chen Tian , Shea Kristina
Published: December 2016

The design and fabrication of hierarchical multi-stable structures using multi-material Additive Manufacturing (AM) is presented. First a reversible bistable unit actuator is designed to serve as the basis of the design hierarchy. With this unit actuator, the authors present monolithically printed proof-of-concept structures that can transform to multiple activated states, all of which are stable without the need for continuous energy input. The equilibrium positions of these hierarchical designs are found through iterative form finding when necessary. The novel structures illustrated in this paper are only made possible through design for AM that exploits the capabilities of a multi-material, inkjet 3D printer. The design procedure is illustrated through two concepts. The first consists of a series of tetrahedra fabricated as tiled deployable triangles with the out-of-plane members consisting of the actuators in the retracted configuration. The second concept consists of multiple shape changing square unit modules tiled in a grid to achieve complex 3D activated states including a hemisphere, a hyperbolic paraboloid, a star and a cube. Their design and prototyping form the foundation for new types of active and deployable 3D printed structures.
Function Modeling: A Study of Sequential Model Completion Based on Count and Chaining of Functions
Authors: Patel Apurva , Kramer William , Summers Joshua D. , Shuffler-Porter Marissa
Published: December 2016

Function models are widely recognized as a useful tool in mechanical engineering conceptual design as a bridge between problem and solution space. Unlike many other engineering design tools that are collaborative allowing many designers to contribute to the design task, function modeling has not been historically presented as a collaborative tool. This paper presents a controlled experimental study that explores the how different initial function models are completed by novice engineers influence the number of functions added to the model. Eighty-eight senior mechanical engineering students were given partial function models to two similarly complex engineering design problems. Each student was asked to complete the function model to best address the problem presented. The number of added functions was compared considering two variables: percent completed of initial seed model (10%, 40%, and 80%), initial chaining of functions (forward, backward, and nucleation). It was found that models for Backward Chaining and Nucleation at 10% initial seed resulted in the greatest addition of functions by the students. Further, Backward Chaining and Nucleation yielded more added functions than Forward Chaining in all seed configurations. Recognizing that there is a difference between Forward Chaining and Backward Chaining or Nucleation, further study is warranted to understand how individuals create function models and which approach yields more useful models to either understand the problem presented or to explore solution options.
Force Analysis of Spatial Single Closed-Loop Overconstrained Mechanisms
Authors: Liu Wenlan , Xu Yundou , Yao Jiantao , Zhao Yongsheng
Published: December 2016

Taking the Bennett and Schatz mechanisms as examples, force analyses of spatial single closed-loop (SSCL) overconstrained mechanisms are demonstrated aiming to obtain the driving forces/torques and joint reactions of this kind of mechanisms. Firstly, regarding the SSCL overconstrained mechanisms as parallel mechanisms with two supporting limbs, the constraint wrenches and actuation wrenches imposed on the moving platform by the two limbs are discussed, and the mobility of each mechanism is analyzed based on the screw theory. Then, the compliance matrices of the limbs’ constraint wrenches are derived, which contribute to solve the statically indeterminate force problem of the mechanisms. Next, by combining the force and moment equilibrium equation of the moving platform with the deformation compatibility equation of the corresponding mechanism, the magnitudes of all constraint wrenches and actuation wrenches are solved. Furthermore, the driving forces/torques and joint reactions are derived. Finally, the numerical and simulation results of the two mechanisms are presented.
Isotropic Analysis of Line Vector Forces and its Application in the Type Synthesis of Redundantly Actuated 3-DOF Translational Parallel Mechanisms
Authors: Xu Yundou , Zhou Xin , Lu Ling , Yao Jiantao , Zhao Yongsheng
Published: December 2016

The load-carrying capacity of a mechanism is closely related to its line vector force. This article presents a thorough isotropic analysis of line vector forces. The results show that the isotropic condition can be satisfied when the line vector forces are evenly distributed on a conical surface with a cone-top angle of 109.472 degrees. By combining the isotropic line vector forces, a method for the type synthesis of 3-DOF, redundantly actuated translational parallel mechanisms (PMs) is proposed, in which the arrangement of the active joints is taken into account in advance. Using this method, a kinematic chain with a twist system reciprocal to both the constraint and actuation wrenches is constructed firstly, and then the active joint reciprocal to the constraint wrenches but not to the actuation wrench is constructed. Thus, a series of typical redundantly actuated PMs with isotropic actuation forces are obtained. Finally, the 4-PRRR PM is analyzed as an example, and the results show that the isotropy of the load-carrying capacity can always be satisfied during its movement.
Extending the Energy System Optimization to New Paradigms
Authors: Abi Chahla Gisèle , Zoughaib Assaad , Farel Romain
Published: December 2016

Energy use optimization of systems is traditionally done by looking for the best thermodynamic operating conditions of the process and heat integration solutions such as networks to redistribute intelligently the heat between different sources and sinks. Hence, there are two emerging situations in industrial parks that call for new methodologies: first, the flow exchanges are not limited to the plant boundaries, and incoming and outgoing flows could generate economic and environmental gains. Second, material such as waste can no longer be neglected in this optimization. Not only the energy conversion potential of material could be investigated, but other conversion options would bring the possibility of turning the non-usable waste into another usable material through chemical processes. This paper present a conceptual framework of optimization for an energy and mass system, and proposes a methodology for integrating conversion processes, with a case demonstration on wooden waste in an industrial activity zone.
Obstacle Identification Through Fast Vector Analysis
Authors: Vingbäck Johan , Lideskog Håkan , Karlberg Magnus , Jeppsson Peter
Published: December 2016

During road travel, obstacles can impede productivity or durability for many different vehicles and render discomfort or injuries for the people within. Using remote sensing techniques, information from the surroundings can be acquired and analysed to identify obstacles ahead. The subsequent analysis can create a decision support for how the vehicle or driver should act upon encountered obstacles, through either autonomous control, guidance to the driver or a combination of both. In this paper, an experimental setup was created to mimic an obstacle in the shape of a speed bump on a flat road. An RGB-D camera was used to acquire information while travelling towards the speed bump. Afterwards, the acquired information was analysed by an estimation of the normal vector for each point in a 2D depth map. The resulting data from the experiments had sufficient resolution, speed and quality to retrieve proper identify obstacles or targets indoors with an accuracy of 2%. Obstacles were measured and identified in less than 20 ms where processing time mainly comprised data transfer from the USB-bus. The obstacle identification can be used to e.g. actively control the vehicle suspension, send feedback to the driver about obstacles ahead or optimise speed and direction for autonomous vehicles.
Framework and Feasibility Study for Pairwise Comparison Tool
Authors: Ellman Asko , Wendrich Robert , Tiainen Tarja
Published: December 2016

In design and engineering context, the use of tools, simulations and multi-realities is already an intrinsic part of design activities, methods and processes. To support participatory design during the ideation phase in a co-creative context, participative tools are needed. User-centered and co-creative design could benefit product creation and innovation process through data-collection (incl. product characteristics and user requirements) from individual data-mining activities.

The traditional approach for customer requirements prioritization is pair-wise comparison. It is used both in the QFD method and in the Pugh matrix method. In practice, this means that a user compares two product characteristics at a time and decides which one of the two is more important or if they are equally important. Determining a suitable user interface for the comparison has proven to be the most demanding phase in the implementation of this method.

This paper presents alternative ways to implement a customer property tool and discusses experiences with some of its implementations. In the first version, the interface is based on the use of numbers, whereas the last version is more visual, interactive and game-like. The feasibility of the tool was studied in user tests carried out in Finland and in the Netherlands.
Control of RF Transmission Characteristics Through Origami Design
Authors: Fuchi Kazuko , Buskohl Philip R. , Joo James J. , Reich Gregory W.
Published: December 2016

The efficient mapping between 2D and 3D spaces offered by origami facilitates the exploration of a vast design space of 3D reconfigurable devices. Many existing origami adaptations for engineering applications assume known folded geometries. However, “what to make” becomes a critical question for design problems where the intuition on the relationship between the geometry and function is limited. This article discusses a systematic design method for folding patterns used to tune electromagnetic performance. Radio frequency transmission characteristics of a frequency selective surface are investigated as an example. The fold stiffness distribution and the embedded actuator locations on a substrate are optimized using the sensitivity information obtained through the electromagnetic analysis in COMSOL. The optimal crease pattern and actuator distribution are used to fold a substrate hosting dipoles of known dimensions. Attaining a smooth optimization process proved to be challenging due to the high sensitivity of the FSS on the dipole orientations. A surrogate optimization problem is solved to achieve a resonant frequency tuning toward a target frequency.
Dynamics of Strongly Coupled Fluid-Filled Micro-Cavities and PMUTs in Integrated Microfluidic Devices
Authors: Dangi Ajay , Deshmukh Dhananjay , Singh Robin , Pratap Rudra
Published: December 2016

In this work, we present a novel device developed by integration of an array of Piezoelectric Micromachined Ultrasonic Transducers (PMUTs) with a microfluidic chip that can be used for characterizing the acoustical properties of the liquid present in the back-cavity of the PMUT. PMUT membrane operates in flexural mode of vibration and it is directly coupled with the cylindrical back-cavity formed during the release of the PMUT membrane. This leads to very strong structural-acoustic coupling between the PMUT and the liquid present in the its back-cavity. Presence of fluid around the thin PMUT membrane causes a significant reduction in the resonant frequencies of the PMUT due to mass loading imposed by the surrounding fluid. It also leads to the excitation of the acoustic modes of the cylindrical back-cavity when the PMUT vibrates near the fundamental acoustic frequencies of the cavity. These acoustic reverberations appear in the vibration response of the PMUT in form of additional resonant peaks. Further we explore the feasibility of capturing the acoustic signature of microbubbles introduced in the back-cavity liquid. Microbubbles are generated on the microfluidic chip using flow focusing technique and introduced in the cylindrical back-cavity of the PMUT through a network of channels and wells made on PDMS and adhered to the PMUT from the backside. This approach can provide an alternative method for on-chip characterization of microbubbles.
Two Approaches to the Induction of Graph-Rewriting Rules for Function-Based Design Synthesis
Authors: Eichhoff Julian R. , Baumann Felix , Roller Dieter
Published: December 2016

In this paper we demonstrate and compare two complementary approaches to the automatic generation of production rules from a set of given graphs representing sample designs. The first approach generates a complete rule set from scratch by means of frequent subgraph discovery. Whereas the second approach is intended to learn additional rules that fit an existing, yet incomplete, rule set using genetic programming. Both approaches have been developed and tested in the context of an application for automated conceptual engineering design, more specifically functional decomposition. They can be considered feasible, complementary approaches to the automatic inference of graph rewriting rules for conceptual design applications.
A Functional Modelling Based Methodology for Testing the Predictions of Fault Detection and Identification Systems
Authors: Papakonstantinou Nikolaos , Proper Scott , Van Bossuyt Douglas L. , O’Halloran Bryan , Tumer Irem Y.
Published: December 2016

Fault detection and identification (FDI) systems, which are based on data mining and artificial intelligence techniques, cannot guarantee a perfect success rate or provide analytical proof for their predictions. This characteristic is problematic when such an FDI system is monitoring a safety-critical process. In these cases, the predictions of the FDI system need to be verified by other means, such as tests on the process, to increase trust in the diagnosis. This paper contributes an extension of the Hierarchical Functional Fault Detection and Identification (HFFDI) system, a combination of a plant-wide and multiple function-specific FDI modules, developed in past research. A test preparation and test-based verification phase is added to the HFFDI methodology. The functional decomposition of the process and the type of the faulty components guides the preparation of specific tests for every fault to be identifiable by the HFFDI system. These tests have the potential to confirm or disprove the existence of the fault(s) in the target process. The target is minor automation faults in redundant systems of the monitored process. The proposed extension of the HFFDI system is applied to a case study of a generic Nuclear Power Plant model. Two HFFDI predictions are tested (a successful and an incorrect prediction) in single fault scenarios and one prediction is tested in a in a two fault scenario. The results of the case study show that the testing phase introduced in this paper is able to confirm correct fault predictions and reject incorrect fault predictions, thus the HFFDI extension presented here improves the confidence of the HFFDI output.
Kinematic Study of a Soft-and-Rigid Robotic Digit for Rehabilitation and Assistive Applications
Authors: Haghshenas-Jaryani Mahdi , Carrigan Wei , Wijesundara Muthu B. J. , Patterson Rita M. , Bugnariu Nicoleta , Niacaris Timothy
Published: December 2016

This paper presents the kinematic study of a pneumatically actuated soft-and-rigid robotic digit designed to be used in exoskeleton-based hand rehabilitation and assistive applications. The soft-and-rigid robotic digit is comprised of three inflatable bellow-shaped structure sections (soft sections) and four semi-rigid sections in an alternating order which correspond to the anatomy of a human finger. The forward and backward bending motions at each soft section (joint) are generated by pressure and vacuum actuation, respectively. The goal here is to investigate the compatibility of the soft robotic digit’s kinematic parameters such as range of motion, center of rotation, and lengthening at the joints with the required anatomical motion of the human finger to ensure proper function and safe interaction. The soft robotic digits were fabricated using silicone rubber materials in a compression molding process for the experimental study. The kinematic parameters of both a human and soft robotic index finger were measured using a motion capture system. The obtained results show that the robotic digit was able to provide the required range of motion: 0–90° at the metacarpophalangeal (MCP) joint, 0–100° at the proximal interphalangeal (PIP) joint, and 0–70° at the distal interphalangeal (DIP) joint. Furthermore, the data show the center of rotation of each soft section (robotic joint) was remotely coincident with that of the corresponding index finger. The lengthening of the three soft sections of the robotic digit were measured to be 7mm, 7mm, and 2mm for the MCP, PIP, and DIP, respectively. The corresponding values for the dorsal skin lengthening of a human index finger is 11mm, 15mm, and 5mm and are longer than the achieved lengthening in the robotic digit.
Design of a Compliant Endoscopic Ultrasound-Guided Radiofrequency Ablation Probe
Authors: Hanks Bradley W. , Frecker Mary , Moyer Matthew
Published: December 2016

Pancreatic cancer is one of the most deadly forms of cancer in the United States. Due to its late diagnosis, only 20% of patients diagnosed with the disease are eligible for surgical resection which is considered the preferred method of treatment. Radiofrequency ablation is a common cancer treatment modality for patients ineligible for open surgery. There is a lack of ablation probes which may be used to generate spherical heating zones which closely match the geometry of typical tumors. In particular, there are no endoscopic ablation probes commercially available in the United States. In this paper the design of a compliant endoscopic radiofrequency ablation probe is presented. This probe features an array of compliant tines which deploy through the cancerous tissue to effectively broaden the ablation zone. A thermal ablation model is used to inform the design of the geometry of the probe. In addition, finite element analysis is used to determine the feasibility of the compliant structures. These design tools are used as aids to inform the design and direct modifications toward a feasible probe which generates a spherical ablation zone.
Control of Galloping Oscillations Through Energy Harvesting Absorber
Authors: Dai Huliang , Abdelmoula Hichem , Abdelkefi Abdessattar , Wang Lin
Published: December 2016

In the present study, we combine the control strategy and energy harvesting performance of a square cylinder subjected to galloping vibrations, by internally installing a piezoelectric cantilever beam with a tip mass. The piezoelectric sheets are attached to the beam to convert the galloping oscillations of the big cylinder into electrical energy from the small cantilever structure. The coupled nonlinear representative model is developed by employing the Euler–Lagrange principle and implementing the Galerkin discretization. The impacts of the electrical load resistance on the coupled frequencies and coupled damping of both structures as well as the onset speed of galloping of the square cylinder are analyzed. The results show that there exists an optimal load resistance that maximizes the onset speed of galloping due to the largest coupled damping ratio. What’s more, the effects of the load resistance on controlling the displacement of the big cylinder and the level of harvested power produced from the small energy harvester are determined. It is indicated that with appropriate parameter values, the displacement of square cylinder can be effectively controlled, and at the same time high values of harvester power can be obtained.
Characterizing the Effective Bandwidth of Tri-Stable Energy Harvesters
Authors: Panyam Meghashyam , Daqaq Mohammed F.
Published: December 2016

This paper aims to investigate the response and characterize the effective frequency bandwidth of tri-stable vibratory energy harvesters. To achieve this goal, the method of multiple scales is utilized to construct analytical solutions describing the amplitude and stability of the intra- and inter-well dynamics of the harvester. Using these solutions, critical bifurcations in the parameter’s space are identified and used to define an effective frequency bandwidth of the harvester. A piezoelectric tri-stable energy harvester consisting of a uni-morph cantilever beam is considered. Stiffness nonlinearities are introduced into the harvesters design by applying a static magnetic field near the tip of the beam. Experimental studies performed on the harvester are presented to validate some of the theoretical findings.
Multi-Objective Robust Optimization Formulations With Operational Flexibility and Discretized Uncertainty
Authors: Azarm Shapour , Lee Yu-Tai
Published: December 2016

Traditional robust optimization formulations can be considered to be “passive” in the sense that they can obtain optimized design and operational solutions for a system for all realizations of uncertainty. However, flexibility in the system’s operation can be used to devise formulations that obtain solutions that are optimum for all realizations of uncertainty while operational variables are used to mitigate or eliminate the effects of uncertainty. The objective of this paper is to extend existing formulations in single-objective robust optimization to multi-objective robust optimization with or without operational flexibility under discretized uncertainty. The formulations with operational flexibility are referred to as flexible optimization. The flexible optimization formulations and corresponding solutions are demonstrated and compared with those from robust and deterministic optimization formulations using numerical examples, and an engineering example with black-box objective and constraint functions.
Modeling the Variability of Glenoid Geometry in Intact Shoulders
Authors: de Vries Charlotte M. , Parkinson Matthew B.
Published: December 2016

The objective of this research is to model the geometric variability of the glenoid (the “socket” component of the “ball and socket” connection of the shoulder joint) of the scapula. The model must capture the observed variability with sufficient resolution such that it informs operative and design decisions. This required the quantification of variability in landmark locations and relevant bone geometry. Landmarks were placed on the existing glenoid meshes, such that they provided enough information to represent the geometry, while being consistent across each glenoid. Additionally, the surface geometry of the glenoid vault was modeled. This required the application of existing mathematical and statistical modeling approaches, including geometric fitting, radial basis functions, and principal component analysis. The landmark identification process represented the glenoid in new manner. The work was validated against existing approaches and CT scans from 42 patients.

A range of information on shoulder geometries can assist with preoperative planning, as well as implant design, for Total Shoulder Arthroplasty (TSA). Principal component analysis (PCA) was used to quantify the variability of shape across the glenoid landmarks, and synthesize new glenoid models. The process of creation of these shoulder geometries may possibly be useful for the study of other joints. The models created will help surgeons and engineers to understand the effects of osteoarthritis on bone geometry, as well as the range of variability present in healthy shoulders.
Cognitive Heuristics in Defining Engineering Design Problems
Authors: Studer Jaryn A. , Yilmaz Seda , Daly Shanna R. , Seifert Colleen M.
Published: December 2016

This paper explores “problem exploration heuristics,” or cognitive strategies used to identify and reframe design problem descriptions. The way a design problem is structured influences the types of ideas a designer generates; in particular, some framings may lead to more creative solutions and using multiple framings can support diverse solutions. Most existing problem exploration strategies have not been derived from empirical studies of engineering design practice. Thus, in our work, we drew upon a sample of engineering design problems and analyzed how the problem descriptions evolved during design. Examining iterations on the problem description allowed us to identify heuristics evident in designers’ recrafting of problem descriptions. Heuristics were defined based on the elements in each problem description and their perceived role in transforming the problem. We present a systematic methodology for identifying problem exploration heuristics, and describe five unique Problem Exploration Heuristics commonly observed in structuring design briefs.
Shape-Morphing Space Frame (SMSF) Using Quadrilateral Bistable Unit-Cell Elements
Authors: Alqasimi Ahmad , Lusk Craig
Published: December 2016

This paper presents a new concept: a Shape-Morphing Space Frame (SMSF) using quadrilateral bistable unit-cell elements. The unit-cells are composed of either eight-bar or seven-bar mechanisms in which design constraints, system of elimination and graph theory are used to design, as a proof of concept, a disk like structure with the ability to morph into a sphere. Or specifically, the circumference of a disk structure is approximated by a ten-sided polygon that would then morph into a hollow sphere structure that is approximated by 60-sided polyhedron. The disk-to-sphere structure is tessellated into ten sides for the latitudes circles and 12 sides for the longitude circles; the disk’s thickness and radius are chosen at the design stage. The strategy in morphing the initial shape of the structure (disk) into its final shape (sphere) is that the radial lines on the surface of the disk bend but do not stretch, whereas the circumferential lines compress. Moreover, the radial lines on the disk become longitude lines on the sphere and the circumferential lines become latitude lines on the sphere. The disk’s thickness splits in half, the upper half becomes the thickness of the upper hemisphere and the lower half becomes the thickness of the lower hemisphere. The concept was successfully prototyped and actuation forces were measured.
Design of Four-Bar-Mechanism Stability Using Over-Constraint
Authors: Alqasimi Ahmad , Lusk Craig
Published: December 2016

This paper presents a new concept and method to design mechanisms’ stability using over-constraint. The designs involve the use of parametric Computer-Aided Design (CAD) software to synthesize a mechanism’s geometry in order to achieve a design’s specific bistability requirements. This method ensures a stable position without the need of a hard-stop. There are two main initial design considerations that need to be met in this analysis. First, both (first and second) state of the mechanism should be chosen and should represent the mechanism’s desired stable positions. The first state is the position that the mechanism was manufactured or assembled at, whereas the second state is the position at which the mechanism is toggled to. The second consideration is the assumption that the magnitude of the joints’ torsional spring stiffness is small i.e. living hinges. The main idea is to attach a Potential Energy Element (PEE), such as a spring or a compliant link, to the four-bar mechanism such that it is unstretched in both stable positions and has to deform (stretch or compress) during the motion between stable states. This approach seems to allow the designer considerable freedom in amount of motion between stable states and in the amount of force required to toggle between stable states.
Analysis of the Effect of Coulomb Friction on Haptic Systems Dynamics
Authors: Budai Csaba , Kovács László L. , Kövecses József
Published: December 2016

Dissipation mechanisms and dissipative forces play a pivotal role in the operations and performance of human-machine interfaces and particularly in haptic systems. Dissipation is a very difficult phenomenon to model. Coulomb friction in general can be the most influential element in systems involving multiple direct contact connections such as joints with transmissions or mechanically guided components. Coulomb friction includes non-smooth discontinuity and can induce complex dynamic behaviours. Very little attention has been paid to the analysis of the effects of Coulomb friction in haptic devices. In this paper we illustrate, by experiment, analysis and simulation, the nature of the dynamic behaviour caused by Coulomb friction in haptic sampled-data systems. We demonstrate that a simple model can represent this behaviour, and show the effects of the haptic system parameters on this dynamics.
Orientation Optimization in Layer-Based Additive Manufacturing Process
Authors: Luo Zhibo , Yang Fan , Dong Guoying , Tang Yunlong , Zhao Yaoyao Fiona
Published: December 2016

The advent of Additive Manufacturing (AM) process has greatly broadened the machining methods. Compared to conventional manufacturing methods, the process planning for AM is totally different. It should avoid process-induced defects such as warpage of overhang features. Process planning for AM should also generate necessary support structure not only to support the overhang structure but also to minimize thermal warpage and residual stress. In order to do so, a general process planning for AM is put forward in this paper. Given a specific part, the first step is the determination of build orientation. The choice of build orientation is one of the critical factors in AM since the build time, the material consumption, the removal of support structure, the deformation within final parts, the mechanical performance, and the surface roughness are all related to the build orientation. This paper utilizes the genetic algorithm to optimize the build orientation by considering the minimum volume of the support structure and the minimum strain energy of a part under specific working conditions. First, a general and feasible process planning for AM is proposed. Then detailed process planning for the optimization of build orientation is developed. The volume of support structure and strain energy are considered independently and corresponding optimal build orientations are obtained through genetic algorithm. A single weighted aggregate optimization function is then constructed to optimize the volume of support structure and strain energy simultaneously. Finally, a bracket is used to verify the feasibility of the proposed method.
Design of a Multi-Palm Robotic Hand for Assembly Tasks
Authors: Movassagh-Khaniki Reza , Hassanzadeh Neda , Makhal Abhijit , Perez-Gracia Alba
Published: December 2016

Some robotic tasks, especially those in which there are interactions between manipulated objects, require the collaborative work of two robotic arms equipped with end-effector grippers or robotic hands. Most of the current applications in which a bimanual task is attempted by a robot use two robot arm manipulators with simple grippers, in which the end-effectors are used for grasping and the remaining motion is performed by the robotic arms. In this work, we propose the design of a highly dexterous multi-fingered robotic hand, able to perform the bimanual task when attached to a simple arm manipulator. Dexterous robotic hands can be designed with more than one splitting stage; their design for a task can be done using kinematic synthesis for tree topologies. The synthesis process is applied in this case to the design of a robotic hand with three palms for a bimanual task consisting of assembling an emergency stop button.
Development, Design and Application of a Fatigue Test Bench for High Precision Flexure Hinges
Authors: Schoenen David , Lersch Sascha , Hüsing Mathias , Corves Burkhard , Klocke Fritz , Hensgen Lars , Klink Andreas
Published: December 2016

Due to their advantages compliant mechanisms are very popular. However, they also have some disadvantages as well. Considering that for micromanipulators, which have macroscopic dimensions and a workspace typically in millimeter range, the disadvantages of compliant mechanisms are not as significant as the feasible benefits by reason of their advantages. For instance the range of notch hinges, which are typically used for micromanipulators, can be increased by the use of precision notch hinges with a narrow web thickness. Precision notch hinges are cut efficiently by wire electrical discharge machining. Therefore, flexure hinges are widely used in precision engineering applications.

Even though electrical discharge machining is a manufacturing process which is based on the thermo-physical material removal principle with less resulting mechanical stress, it still induces thermal stress on the component. It can be assumed that these influences have an impact on the component’s performance, in particular when the component has filigree structures like precision notch hinges. However, experimental studies on the fatigue of compliant joints are currently missing in research activities.

To analyze the manufacturing related influences on the performance of precision notch hinges a series of fatigue tests have to be performed. Thus, a suitable test bench for fatigue testing of precision notch hinges is designed and the used transmission mechanism is explained. Furthermore, the adjustment mechanism for the swivel angle as well as the adjustment mechanism for different loadings of the test specimens are discussed. Additionally, to avoid incorrect loading several design features are explained. To obtain reliable results, the filigree test specimens have to be positioned on the test bench reproducibly in order to ensure recurring test conditions. Thus, the positioning process is explained. In order to increase the number of tested notch hinges, several test specimens are tested simultaneously under the same conditions. Hence, a clear detection of the maximum number of load cycles of each test specimen is ensured by a detection mechanism. This contribution ends with the presentation of preliminary results of the life expectancy analyses of precision notch hinges and a brief discussion of the results.
The Hybrid Predictive Dynamics Method for Analysis, Simulation and Prediction of Human Motion
Authors: Hariri Mahdiar
Published: December 2016

The ‘Hybrid Predictive Dynamics Method for Digital Human Modeling’ is analyzed in this work. The ‘Hybrid’ prefix mentioned in the literature recently [1], refers to the use of motion capture data for improving human motion simulations. This use of motion capture compensates for the inherent weaknesses of purely theoretical motion prediction due to deficiencies in computational power or available theoretical backgrounds. In this work, it is shown that while using the ‘Hybrid’ the more precisely and finely the human motion is modeled (if computational and theoretical limitations allow), the less will be the need for the ‘Hybrid’ method and the more will the human model be able to change the prediction if the inputs are varied (cause and effect). Several human motion scenarios are mentioned in this work. These motion tasks are: “Jogging around Markers”, “Rolling Over”, “Getting up from Prone”, “Vertical Jumping” and “Kneeling and Aiming”. The digital human model is a full-body, three dimensional model with 55 degrees of freedom. Six degrees of freedom specify the global position and orientation of the coordinate frame attached to the pelvic point of the digital human and 49 degrees of freedom represent the revolute joints which model the human joints and determine the kinematics of the entire digital human. Motion is generated by a multi-objective optimization approach. The optimization problem is subject to constraints which represent the limitations of the environment, the digital human model and the motion task. Design variables are the joint angle profiles. All the forces, inertial, gravitational as well as external, are known, except the ground reaction forces. The feasibility of the generation of that arbitrary motion by using the given ground contact areas is ensured by using the well-known Zero Moment Point (ZMP) constraint.
Determination of Optimal Unit-Cell Size of Homogeneous Conformal Unit-Cell Lattice Structure Using Solid Shape Matching
Authors: Alzahrani Mahmoud A. , Choi Seung-Kyum
Published: December 2016

With rapid developments and advances in additive manufacturing technology, lattice structures have gained considerable attention. Lattice structures are capable of providing parts with a high strength to weight ratio. Most work done to reduce computational complexity is concerned with determining the optimal size of each strut within the lattice unit-cells but not with the size of the unit-cell itself. The objective of this paper is to develop a method to determine the optimal unit-cell size for homogenous periodic and conformal lattice structures based on the strain energy of a given structure. The method utilizes solid body finite element analysis (FEA) of a solid counter-part with a similar shape as the desired lattice structure. The displacement vector of the lattice structure is then matched to the solid body FEA displacement results to predict the structure’s strain energy. This process significantly reduces the computational costs of determining the optimal size of the unit cell since it eliminates FEA on the actual lattice structure. Furthermore, the method can provide the measurement of relative performances from different types of unit-cells. The developed examples clearly demonstrate how we can determine the optimal size of the unit-cell based on the strain energy. Moreover, the computational cost efficacy is also clearly demonstrated through comparison with the FEA and the proposed method.
Computer Aided Visualization Tool for Part Quality Analysis of Additive Manufacturing Process
Authors: Taufik Mohammad , Jain Prashant K.
Published: December 2016

This paper presents a novel Computer Aided Visualization (CAV) tool to visualize and perform part quality analysis for Additive Manufacturing (AM) before actual fabrication of the part. An algorithm has been developed to extrude the 2D sliced contours to turn them into 3D layered model in the CAD environment. Extrude feature has been used to maintain the high level of precision during virtual fabrication stage. The part quality related issues were identified layer-by-layer by superposition of base model on its virtual layered model. The performance of the proposed automated modelling system is evaluated on different prototype surfaces related to part quality issues. With the proposed Computer Aided Visualization (CAV) tool, users have the facility to modify locally digital product models. The analysis of digital models can be used to generate a report on issues induced in Additive Manufacturing (AM). As a result, of this, the pre-processing and post preparation stage can be altered for optimal results. The proposed tool can significantly decrease the manufacturing lead time and cost needed for quality product development. Furthermore, the CAV tool would be very efficient for custom analysis and rapid product understanding purpose.
Heat Assisted Single Point Incremental Forming of Polymer Sheets
Authors: Kulkarni Shubhamkar , Sreedhara Vijay Sarthy Mysore , Mocko Gregory
Published: December 2016

The objective of this research is to study the improvement in the formability of thermoplastics using heat assisted single point incremental forming. Single point incremental forming is a production process for forming sheet materials without the use of dedicated tooling (dies/molds). The process is an alternative to thermoforming for low volume forming of sheets. It involves forming the final shape through a series of localized incremental deformations. It has been observed that heat assisted techniques have shown an improvement in the formability limits for sheet metals. In this research, this concept has been tested for improving the formability of polymer sheets. Hot air us used to increase the temperature within a localized region in front of the tool. A single point incremental forming device is modified through the development of a specialized tool holder and nozzle which heats the polymer sheet to temperatures higher than the room temperature but below the glass transition temperature of the polymer and applies the forming loads.

The results from the experiments are summarized as: i) the formability angle increases of polystyrene from 27 degrees to 46 degrees when comparing room temperature forming to forming at an elevated temperature (170°F–180 °F), ii) a reduction in the forces needed for forming is observed qualitatively, and iii) the surface finish on the formed parts do not show visible change. This demonstrates promise of manufacturing complex shapes from thermoplastic polymer sheets using heat assisted incremental forming. Future research includes 1) simulating the localized deformation of the material to enable process planning, 2) quantifying the forming forces and heat control of the system, and 3) exploring the manufacturing technique to other materials.
System for In Vivo Nanoinjection of Tissues
Authors: Jones Talmage H. , Jensen Brian D.
Published: December 2016

This paper investigates the design of a nano-injection system that can deliver genetic material to cells within live tissue. The approach to creating such a system was to create candidate designs that meet all the requirements for successful in vivo injection and can be fabricated using silicon etching. The designs were tested through large-scale prototyping and through models that describe the systems’ behavior on the micrometer scale. One design consists of an array of lances on a rigid backing. The other design consists of an array of lances grouped in sets of three on a backing that can conform to the shape of the tissue being injected. Each design was prototyped in 3D printed ABS plastic. Preliminary results were qualitative and showed that the rigid and flexible designs performed similarly on mostly flat and irregular surfaces. On convex surfaces with a strong curvature (radius of curvature of about 2 cm), the flexible array gave slightly better results. Final testing gave a quantitative comparison of the two designs’ efficiencies on strongly curved convex surfaces. These results supported the preliminary results that the flexible array is more efficient in reaching points on the tissue than the rigid array is. As the applied force increased, each array performed more efficiently.
A Degree-Based Decision-Centric Model for Complex Networked Systems
Authors: Sha Zhenghui , Panchal Jitesh H.
Published: December 2016

The system-level structure and performance of complex networked systems (e.g., the Internet) are emergent outcomes resulting from the interactions among individual entities (e.g., the autonomous systems in the Internet). Thus, the systems evolve in a bottom-up manner. In our previous studies, we have proposed a framework towards laying complex systems engineering on decision-centric foundations. In this paper, we apply that framework on modeling and analyzing the structure and performance of complex networked systems through the integration of random utility theory, continuum theory and percolation theory. Specifically, we propose a degree-based decision-centric (DBDC) network model based on random utility theory. We analyze the degree distribution and robustness of networks generated by the DBDC model using continuum theory and percolation theory, respectively. The results show that by controlling node-level preferences, the model is capable of generating a variety of network topologies. Further, the robustness of networks is observed to be highly sensitive to the nodes’ preferences to degree. The proposed decision-centric approach has two advantages: 1) it provides a more general model for modeling networked systems by considering node-level preferences, and 2) the model can be extended by including non-structural attributes of nodes. With the proposed approach, systems that are evolved in a bottom-up manner can be modeled to verify hypothesized evolution mechanisms. This helps in understanding the underlying principles governing systems evolution, which is crucial to the development of design and engineering strategies for complex networked systems.