bluuebunny/crossref_metadata_2025 huggingface dataset:
Pose Changes From a Different Point of View
Authors: Chirikjian Gregory S. , Mahony Robert , Ruan Sipu , Trumpf Jochen
Published: November 2017

For more than a century, rigid-body displacements have been viewed as affine transformations described as homogeneous transformation matrices wherein the linear part is a rotation matrix. In group-theoretic terms, this classical description makes rigid-body motions a semi-direct product. The distinction between a rigid-body displacement of Euclidean space and a change in pose from one reference frame to another is usually not articulated well in the literature. Here we show that, remarkably, when changes in pose are viewed from a space-fixed reference frame, the space of pose changes can be endowed with a direct product group structure, which is different from the semi-direct product structure of the space of motions. We then show how this new perspective can be applied more naturally to problems such as monitoring the state of aerial vehicles from the ground, or the cameras in a humanoid robot observing motions of its hands.
Evaluation of Paravalvular Leakage in Novel Mechanical Heart Valve
Authors: Saxena Ankit , Shad Rohan , Mathur Mrudang , Chattoraj Anwesha , Shad Sujay
Published: November 2017

We developed a new mechanical heart valve prototype with a unique mechanism for attachment to cardiac tissue. The development of novel prosthetic heart valve systems requires careful assessment of paravalvular leaks — leakage of fluid that takes place between the valve and the cardiac tissue it is attached to. Traditional methods of testing paravalvular leaks in flow chambers are not ideal for novel devices and may underestimate its true extent. In this paper we developed a novel method of quantifying paravalvular leaks involving the use of 3D printed prototype heart valves and cadaveric bovine hearts, and compared the results with those from commercially available Medtronic ATS mechanical bileaflet valves. The average leak in our final prototype heart valves were found to be 0.13 ml/sec, compared to 0.33 ml/sec in the ATS valve.
Tangible Augmented Reality Model to Support Manual Assembly
Authors: Matteucci Marco , Raponi Damiano , Mengoni Maura , Peruzzini Margherita
Published: November 2017

Manual work is a cornerstone of manufacturing, also for factories of Industry 4.0 era. Use cases of manual work regard the production of single item, customized assemblies, small batches. Several injuries can be caused or aggravated by manual handling activities at work. Moreover, the efficiency of the whole process can benefit from correct body posture, parts’ visibility and accessibility. Finally, manual work is strongly human-centered and its performance is affected by the expertise, the level of knowledge, attitudes and belief of workers.

In this complex context where multiple factors such as Efficiency, Work Performance, Ergonomics and Safety relate each other to achieve a satisfactory smart industry, the paper proposes an innovative Tangible Augmented Reality platform to train and assist workers during the manual handling and assembly tasks necessary to produce consumer goods with high aesthetic qualities. The proposed platform is the result of the application of a multipath methodology to link health and safety elements, typologies of injuries, ergonomics factors and relative qualitative and quantitative assessment methods and ergonomics analysis tools. The TAR platform allows the worker to consult the assembly instructions in a simple and user friendly way and to be informed by potential risk of injuries by a real-time alert. Based on video mapping techniques, the TAR system superimposes the necessary digital contents on the physical model of the product while the operator is building it.
Application Kinetic Energy Shaping to Controlling and Anticontrolling Chaotic Gait of Underactuated Compass-Gait Bipedal Robot
Authors: Xie Jin , Sun Bowen , Wei Wei , Liu Zhaohui
Published: November 2017

Being different from uncontrolled and unpowered biped, an underactuated compass-gait bipedal robot is the one actuated at the ankle. Energy is inputted to control the gait of biped. Based on kinetic energy shaping, controlling and anti-controlling of chaotic gait are investigated in this paper. In order to provide energy at proper instant, the energy shaping function is modified as ksinθ1+θ0θ.12. This modification permits of taking the characteristic of gait of the biped into consideration by taking the best initial phase as initial phase, i.e. θ0=θ0*. The results of simulation show that the control scheme ksinθ1+θ0θ.12 is efficient in controlling and anti-controlling chaotic gait.
Scalable Pressure Sensor Based on Electrothermally Operated Resonator
Authors: Hajjaj Amal Z. , Hafiz Md Abdullah Al , Alcheikh Nouha , Younis Mohammad I.
Published: November 2017

We experimentally demonstrate a new pressure sensor that offers the flexibility of being scalable to small sizes up to the nano regime. Unlike conventional pressure sensors that rely on large diaphragms and big-surface structures, the principle of operation here relies on convective cooling of the air surrounding an electrothermally heated resonant structure, which can be a beam or a bridge. This concept is demonstrated using an electrothermally tuned and electrostatically driven MEMS resonator, which is designed to be deliberately curved. We show that the variation of pressure can be tracked accurately by monitoring the change in the resonance frequency of the resonator at a constant electrothermal voltage. We show that the range of the sensed pressure and the sensitivity of detection are controllable by the amount of the applied electrothermal voltage. Theoretically, we verify the device concept using a multi-physics nonlinear finite element model. The proposed pressure sensor is simple in principle and design and offers the possibility of further miniaturization to the nanoscale.
Lithium-Ion Laptop Battery Testing and Energy Recycling
Authors: Zhou Jiexin , Wang Qing , Wang Jie
Published: November 2017

Before recycling used lithium-ion laptop batteries, testing and sorting work is needed through charge and discharge tests. For current lithium-ion battery charge and discharge tests, the battery is discharged through a resistor. Thus, the energy in the process is all dissipated.

In this paper, an energy-recycling battery test system model is introduced. In the system, a Li-ion 18650 battery can be charged at a constant current mode and a constant voltage mode and discharged at a constant current mode, which are realized by PWM-controlled DC-DC converters. The modes are automatically switched through a controller. In the discharging process, energy is transferred from the under-test battery to a storage battery, which can also serve as a charging source instead of the DC power supply to recycle the energy.

The system is simulated using Matlab Simulink. Its test accuracy and energy-transferring efficiency is considerable. According to the simulation results, the system can save about 50% energy overall in one charge and discharge cycle.
Dynamic Response and Identification of Tower-Cable-Roller Battery Interactions in Ropeways
Authors: Arena Andrea , Carboni Biagio , Lacarbonara Walter , Babaz Mathieu
Published: November 2017

Towers, roller batteries, propelling cables and vehicles are the substructures of ropeway transportation systems. High-fidelity modeling of their dynamical interactions together with a reliable identification is a key step towards the prediction of the system response under various transit conditions as well as to investigate design optimization strategies. In this work, a nonlinear mechanical model for the dynamical description of cablecar ski lift systems is discussed. The investigation is focused on the modal features and the forced dynamic response caused by the vehicles transit across the so-called compression towers. The model is validated according to experimental data acquired via a custom-design sensor network. The Enhanced Frequency Domain Decomposition (EFDD) method is employed to identify the frequencies and damping ratios.
Baseline Experimental Results on the Effect of Oil Temperature on Shrouded Meshed Spur Gear Windage Power Loss
Authors: Delgado Irebert R. , Hurrell Michael J.
Published: November 2017

Rotorcraft gearbox efficiencies are reduced at increased surface speeds due to viscous and impingement drag on the gear teeth. This windage power loss can affect overall mission range, payload, and frequency of transmission maintenance. Experimental and analytical studies on shrouding for single gears have shown it to be potentially effective in mitigating windage power loss. Efficiency studies on unshrouded meshed gears have shown the effect of speed, oil viscosity, temperature, load, lubrication scheme, etc. on gear windage power loss. The open literature does not contain experimental test data on shrouded meshed spur gears. Gear windage power loss test results are presented on shrouded meshed spur gears at elevated oil inlet temperatures and constant oil pressure both with and without shrouding. Shroud effectiveness is compared at four oil inlet temperatures. The results are compared to the available literature and follow-up work is outlined.
Experimental Determination of Dominant Multipliers in Milling Process by Means of Homogeneous Coordinate Transformation
Authors: Kiss Adam K. , Bachrathy Daniel , Stepan Gabor
Published: November 2017

In this contribution, a chatter detection method is investigated for milling operations. The proposed approach can give not only qualitative condition (stable or unstable), but a quantitative measure of stability. For this purpose, it requires an external excitation of stable machining condition. Transient vibration of the perturbation is captured by means of stroboscopic section, and the corresponding monodromy operator is approximated by its projection to the subspace of the dominant modes. The monodromy matrix is determined with the application of homogeneous coordinate representation. Then, the periodic solution and the dominant characteristic multipliers are calculated and their modulus determines the quantitative measure of stability condition.
Cost Minimization in Metal Additive Manufacturing Using Concurrent Structure and Process Optimization
Authors: Huang Runze , Ulu Erva , Kara Levent Burak , Whitefoot Kate S.
Published: November 2017

Metals-additive manufacturing (MAM) is enabling unprecedented design freedom and the ability to produce significantly lighter weight parts with the same performance, offering the possibility of significant environmental and economic benefits in many different industries. However, the total production costs of MAM will need to be reduced substantially before it will be widely adopted across the manufacturing sector. Current topology optimization approaches focus on reducing total material volume as a means of reducing material costs, but they do not account for other production costs that are influenced by a part’s structure such as machine time and scrap. Moreover, concurrently optimizing MAM process variables with a part’s structure has the potential to further reduce production costs. This paper demonstrates an approach to use process-based cost modeling in MAM topology optimization to minimize total production costs, including material, labor, energy, and machine costs, using cost estimates from actual MAM operations. The approach is demonstrated in a simple case study of a Ti64 cantilever produced with electron beam melting (EBM). Results of a concurrent optimization of the part structure and EBM process variables are compared to an optimization of the part structure alone. The results show that, once process variables are considered, it is more cost effective to include more material in the part through a combination of (1) building additional thin trusses with a faster laser speed and (2) increasing the thickness of other truss members and decreasing laser velocity to create larger melt pools that reduce the number of passes required, thereby reducing build time. Concurrent optimization of the part’s structure and MAM process parameters leads to 7% lower estimated total production costs and approximately 50% faster build time than optimizing the part’s structure alone.
Design of Wearable Lower Leg Orthotic Based on Six-Bar Linkage
Authors: Ghosh Shramana , Robson Nina , McCarthy J. M.
Published: November 2017

The paper presents the design of a lower leg orthotic device based on dimensional synthesis of multi-loop six-bar linkages. The wearable device is comprised of a 2R serial chain, termed the backbone, sized according to the wearer’s limb anthropometric dimensions. The paper is a result of our current efforts in proposing a systematic process for the development of 3D printed customized assistive devices for patients with reduced limb mobility, based on anthropometric data and physiological task.

To design the wearable device, the physiological task of the limb is obtained using an optical motion capture system and its dimensions are set such that it matched the lower leg kinematics as closely as possible. As a next step a six-bar linkage is synthesized and ensured that its motion is as close as possible to the physiological task. Next, the 2R backbone is replaced by the wearer’s limb to provide the skeletal structure for the multi-loop wearable device. During the final stage of the process the 2R backbone is relocated to parallel the human’s limb on one side, providing support and stability. The designed device can be secured to the thigh of the user to guide the lower leg without causing any discomfort and to ensure a natural physiological gait trajectory. This results in orthotic device for assisting people with lower leg injuries with compact size and better wearability.
Design of a Parallel Architecture Robotic Spine Exoskeleton With Series Elastic Actuators
Authors: Ophaswongse Chawin , Murray Rosemarie C. , Agrawal Sunil K.
Published: November 2017

This paper proposes a novel methodology for the design of series elastic actuators in parallel-actuated platforms which have full six degrees-of-freedom in position and orientation. Series elastic actuators can potentially contribute to lower power consumption and provide a better human-machine interface for the user. This is an important consideration in the use of a robotic spine exoskeleton for human subjects, which motivates this work. In the study of parallel-actuated systems with full six degrees-of-freedom, the effect of compliance in series with actuators has not been adequately studied from the perspective of kinematics and wrench capabilities. These analyses are performed in this paper with the goal to improve the design of the robotic spine exoskeleton (ROSE) and its human usage.
Design Optimization of Folding Solar Powered Autonomous Underwater Vehicles Using Origami Architecture
Authors: Hur Doe Young , Peraza Hernandez Edwin , Galvan Edgar , Hartl Darren , Malak Richard
Published: November 2017

Recently, the importance of design process with unknown parameter increased. On the other hand, the design of Autonomous Underwater Vehicles (AUVs) is a difficult challenge since it requires the consideration of various aspects such as mission range, controllability, energy source, and carrying capacity. A design process for novel type of AUV constructed using an origami-based structure that includes active material actuators and solar panels is proposed in this paper. To increase the efficiency in the three-dimensional shape modeling of the AUV, the shape of the outer surface is parameterized by a finite set of variables using shape functions. Here, the AUV should operate underwater via electrical power with the batteries being charged periodically using solar panels. The ability of the AUV to transport cargo such as instrumentation is also addressed. The design parameters include the total height and width of the AUV. As these dimensions of the AUV might vary in a non-preferential manner based on particular mission goals, these dimensions are considered as design parameters in a multi-objective optimization setting. The Predictive Parameterized Pareto Genetic Algorithm (P3GA) is selected as the optimization method to determine a Pareto frontier of design options with desired characteristics for a variety of missions for the AUV. The evaluation of each AUV design entails quantitative assessment of the origami fold pattern determined using a method developed by the authors and Computational Fluid Dynamics (CFD) analysis. The development of a design process that addresses the design optimization of the AUV considering its hydrodynamic performance and origami aspects is the main topic of this paper.
Towards the Optimal Crown-to-Implant Ratio in Dental Implants
Authors: Sego T. J. , Hsu Yung-Ting , Chu Tien-Min Gabriel , Tovar Andres
Published: November 2017

Short dental implants are commonly recommended to be implemented with small crown-to-implant (C/I) ratios due to their mechanical stability — decreasing C/I ratios cause less deformation in skeletal tissue under occlusal force. However, the long-term stability of short implants with high C/I ratios remains a controversial issue due to biomechanical complications. This study evaluates the strain distribution and functional implications in an implant-supported crown with various C/I ratios using a high-fidelity, nonlinear finite-element model. Several clinical scenarios are simulated by loading implants with various implant lengths (IL) and crown heights (CH). Strain distribution and maximum equivalent strain are analyzed to evaluate the effects and significance of CH, IL, and the C/I ratio. The study shows underloading for certain implant configurations with high C/I ratio. Increasing IL and decreasing C/I in moderation demonstrates a positive effect in long-term stability.
Experimental Characterization of Pressure Loss Caused by Flow Through Foldcore Sandwich Structures
Authors: Klett Yves , Zeger Carla , Middendorf Peter
Published: November 2017

Folded structures based on different tessellation types have been investigated as alternatives to conventional sandwich core materials like honeycombs and foams. Besides the mechanical performance offered by such foldcores, they feature some unique properties that can be used to integrate additional functionalities. One of these is the possibility to generate large cross-section channels within the sandwich core that can be used for gas and fluid transport. In this study, we present an experimental setup to measure pressure loss within foldcore sandwich panels, and compare results for seven different foldcore configurations.
Analysis of the Housing Vibration of a Rotorcraft Planetary Gear Using a Finite Element/Contact Mechanics Model
Authors: Cooley Christopher G. , Hood Adrian A.
Published: November 2017

This study investigates the planetary gear housing vibration for rotorcraft systems with equally spaced and diametrically opposed planets using a finite element/contact mechanics model. This approach permits accurate housing deflection calculations at each time instant that result from the changing contact conditions on all gear teeth and elastic deformations of each gear. Planetary gears with diametrically opposed planets have larger amplitude vibrations and more frequency content than those with equally spaced planets. Parametric studies show that although the frequency content does not change with changes in the system’s parameters, the amplitudes of response at these frequencies are meaningfully impacted. The frequency components of the acceleration spectra can have additional content when the planetary gear has manufacturing and assembly errors. Each error case results in different frequency content in the acceleration spectra. Understanding these housing vibrations is beneficial for interpreting measured accelerometer signals to detect and classify damage.
Nonlinear Static and Dynamic Behavior of an Imperfect Circular Microplate Under Electrostatic Actuation
Authors: Jallouli Aymen , Kacem Najib , Lardies Joseph
Published: November 2017

In this article, we investigate the nonlinear static and dynamic behavior of a clamped circular microplate in presence of imperfections. By taking in account the von Kàrmàn nonlinearity, the geometrical imperfections lead to a significant delay in static pull-in occurrence. Numerical simulations are performed in the frequency domain to study the dynamic behavior under primary resonance. A parametric analysis is conducted with respect to actuation voltages and initial deflection in order to capture the competition between hardening and softening behavior. Interestingly, we show that a geometric imperfection can change the type of nonlinear response from softening to hardening. In practice, the imperfection can be functionalized to enhance the performances of capacitive micromachined ultrasonic transducers.
Part Separation Methods for Assembly Based Design in Additive Manufacturing
Authors: Oh Yosep , Behdad Sara , Zhou Chi
Published: November 2017

The goal of this study is to develop a heuristic part separation algorithm for assembly-based design in Additive Manufacturing (AM). The objective is to minimize the total processing time including both buildup time and assembly time. In the proposed algorithm, the part separation is recursively conducted until the number of assemblies reaches a threshold value. The proposed method helps designers determine the proper number of assemblies and their buildup orientations. A numerical example is provided to illustrate the application of the algorithm.
Multi-Goal Path Planning for Robotic Agents With Discrete-Step Locomotion
Authors: Sagar Keerthi , Zlatanov Dimiter , Zoppi Matteo , Nattero Cristiano , Muthuswamy Sreekumar
Published: November 2017

The paper introduces a new, intrinsically discrete, path planning and collision-avoidance problem, with multiple robots and multiple goals. The issue arises in the operation of the novel Swing and Dock (SaD) locomotion for a material handling system. Its agents traverse a base grid by sequences of rotations (swings) around fixed pins. Each agent must visit an array of goal positions in minimal time while avoiding collisions. The corresponding off-line path-planning problem is NP-hard. We model the system by an extended temporal graph and introduce two integer linear programming (ILP) formulations for the minimization of the makespan, with decision variables on the nodes and the edges, respectively. Both optimizations are constrained and favor idling over detours to reduce mechanical wear. The ILP formulations, tailored to the SaD system, are general enough to be applicable for many other single- and multi-agent problems over discretized networks. We have implemented the ILPs with a gurobi solver. Computational results demonstrate and compare the effectiveness of the two formulations.
An XY Nanopositioner With a Self-Adjusting Stiffness Center Module
Authors: Liu Zhiqing , Zhang Zhen
Published: November 2017

This paper presents an innovative large stroke XY compliant nanopositioner with a self-adjusting stiffness center (SASC) module in order to minimize the in-plane parasitic rotation. Double parallelogram flexure is utilized to achieve kinematics decoupling. Moreover to realize SASC, an additional planar joint based on parallelogram flexure is adopted, which significantly reduces the in-plane moment. SASC design approach makes the stiffness center adjust by itself and stay fixed by the variation of the stiffness of parallelogram flexures when the stage is in motion. In a case study, a 1mm × 1 mm XY nanopositioner with a SASC module is presented in details. Finite element analysis (FEA) results show that the proposed XY positioner is capable to achieve the required millimeters stroke, and significantly reduces parasitic rotation with the SASC design.
Design of Variable-Density Structures for Additive Manufacturing Using Gyroid Lattices
Authors: Zhang Botao , Mhapsekar Kunal , Anand Sam
Published: November 2017

Additive manufacturing (AM) processes enable the creation of lattice structures having complex geometry which offer great potential for designing light weight parts. The combination of AM and cellular lattice structures provide promising design solutions in terms of material usage, cost and part weight. However, the geometric complexity of the structures calls for a robust methodology to incorporate the lattices in parts designs and create optimum light weight designs. This paper proposes a novel method for designing light weight variable-density lattice structures using gyroids. The parametric 3D implicit function of gyroids has been used to control the shape and volume fraction of the lattice. The proposed method is then combined with the density distribution information from topology optimization algorithm. A density mapping and interpolation approach is proposed to map the output of topology optimization into the parametric gyroids structures which results in an optimum lightweight lattice structure with uniformly varying densities across the design space. The proposed methodology has been validated with two test cases.
A Lobster-Inspired Hybrid Actuator With Rigid and Soft Components
Authors: Chen Yaohui , Le Sing , Tan Qiao Chu , Lau Oscar , Song Chaoyang
Published: November 2017

Soft actuators have drawn significant attentions from researchers with an inherently compliant design to address the safety issues in physical human-robot interactions. However, they are also vulnerable and pose new challenges in the design, fabrication, and analysis due to their inherent material softness. In this paper, a novel hybrid actuator design is presented with bio-inspirations from the lobster, or crustaceans in a broader perspective. We enclose a soft chamber with rectangular crosssection using a series of articulated rigid shells to produce bending under pneumatic input. By mimicking the shell pattern of lobsters’ abdomen, foldable rigid shells are designed to provide the soft actuator with full protection throughout the motion range. The articulation of the rigid shells predefines the actuator’s bending motions. As a result, the proposed design enables one to analyze this hybrid actuator with simplified quasi-static models and rigid-body kinematics, which are further validated by mechanical tests. This paper demonstrates that the proposed hybrid actuator design is capable of bridging the major design drawbacks of the entirely rigid and soft robots while preserving their engineering merits in performance.
Towards a Better Design Team Formation: A Review of Team Effectiveness Models and Possible Measurements of Design-Team Inputs, Processes, and Outputs
Authors: Takai Shun , Esterman Marcos
Published: November 2017

Cooperation among team members and good teamwork are essential to successfully complete design projects. As such, engineering students are expected to learn how to design and work effectively in a team. While, team-based project courses have been implemented in almost all engineering and engineering technology disciplines, achieving full contribution by all team members has been a persistent challenge in design and other engineering disciplines. This paper proposes a possible approach to establish guidelines to form design teams. In this paper, we first review team-effectiveness models. We then propose a design-team-effectiveness model, which will study associations between inputs, processes, and outputs in order to improve team processes and maximizes team performance through design team composition, work structure and improved team processes. Finally, we propose (1) measurements of design-team inputs, processes, and outputs, and (2) approaches to analyze associations among inputs, processes, and outputs.
Two-Stage Modeling of Customer Choice Preferences in Engineering Design Using Bipartite Network Analysis
Authors: Fu J. Sophia , Sha Zhenghui , Huang Yun , Wang Mingxian , Fu Yan , Chen Wei
Published: November 2017

Customers’ choice decisions often involve two stages during which customers first use noncompensatory rules to form a consideration set and then make the final choice through careful compensatory tradeoffs. In this work, we propose a two-stage network-based modeling approach to study customers’ consideration and choice behaviors in a separate but integrated manner. The first stage models customer preferences in forming a consideration set of multiple alternatives, and the second stage models customers’ choice preference given individuals’ consideration sets. Specifically, bipartite exponential random graph (ERG) models are used in both stages to capture customers’ interdependent choices. For comparison, we also model customers’ choice decisions when consideration set information is not available. Using data from the 2013 China auto market, our results suggest that exogenous attributes (i.e., car attributes, customer demographics, and perceived satisfaction ratings) and the endogenous network structural factor (i.e., vehicle popularity) significantly influence customers’ decisions. Moreover, our results highlight the differences between customer preferences in the consideration stage and the purchase stage. To the authors’ knowledge, this is the first attempt of developing a two-stage network-based approach to analytically model customers’ consideration and purchase decisions, respectively. Second, this work further demonstrates the benefits of the network approach versus traditional logistic regressions for modeling customer preferences. In particular, network approaches are effective for modeling the inherent interdependencies underlying customers’ decision-making processes. The insights drawn from this study have general implications for the choice modeling in engineering design.
Development of an Automated Flexible Micro-Soldering Station
Authors: Venkatesan Vinoth , Cappelleri David J.
Published: November 2017

This paper describes a flexible automated soldering system to handle meso and micro-scale soldering operations. The system is guided by a vision system and consists of two micromanipulators, an XY motion stage, and a solder pen with an automatic solder feeder. One micromanipulator is used to hold and position the solder pen and attached solder feeder in the workspace; the second micromanipulator is used to hold and position the wire(s) to be soldered on to a printed circuit board (PCB). After hardware and vision system calibration, the user can select point(s) from a real-time image of the workspace for the desired soldering operations to occur. The soldering process is then carried out automatically two different ways: 1. By servoing the XY motion stage with the PCB to position it under the soldering manipulator followed by the solder operation; or 2. By moving the soldering manipulator to the target soldering sites on the PCB that remain stationary. Experimental results for both scenarios are presented and discussed for soldering single and multiple wires at a time. This system provides a flexible manufacturing solution for operations that demand custom micro-soldering operations in a 2D plane.
Sequential Decision Process for Tradespace Exploration by Bounding Probabilistic Decision Criteria Using Mean-Risk Analysis
Authors: Chhabra Jaskanwal P. S. , Warn Gordon P.
Published: November 2017

Uncertainty is an integral part of decision making. While performing tradespace analysis multiple design alternatives need to be compared with respect to uncertain decision criteria in order to identify non-dominated design alternatives. However when the decision criteria is obtained from a computationally intensive numerical analysis or from an experimental analysis it might not be feasible to precisely derive distributions of the decision criteria for all design alternatives in the tradespace. In this study it is hypothesized that the availability of precise distributions of decision criteria for all design alternatives in the tradespace is not necessary and appropriate decisions can be made on the basis of imprecise distributions of decision criteria. Key contribution of this study is to investigate an approach using mean-risk analysis to sequentially evaluate a tradespace of design alternatives by bounding and sequentially reducing the imprecision in evaluation of experimental/numerical performance. A sequential decision process is presented where models of increasing fidelity are used to discriminate dominated design alternatives from the tradespace on the basis of imprecise distributions of decision criteria. Application of the framework is demonstrated on a multi-objective discrete choice problem of designing a two bar truss.
Perceptions of Prototypes: Pilot Study Comparing Students and Professionals
Authors: Lauff Carlye , Kotys-Schwartz Daria , Rentschler Mark E.
Published: November 2017

Just as design is a fundamental part of engineering work, prototyping is an essential part of the design process. For many engineering design courses, students must develop a final prototype as part of the course requirements. And in industry, engineers build multiple prototypes when creating a product for market. Although prototyping is core to design education, there is a lack of research on understanding the perceptions and usage of prototypes from both students and professionals. Without understanding students’ perceptions of prototypes, we cannot adequately train them. Likewise, without knowing how professionals use prototypes, we cannot translate these practices back to design education.

This paper reports on the pilot study comparing the perceptions of prototypes between mechanical engineering students and professional engineers. The findings indicate that the interpretation of the term “prototype” varies between students and professionals. Specifically, these mechanical engineering students have a more narrow perception and identify prototypes as only having a few key elements, namely for building and testing functionality and feasibility of physical elements in a product. Comparatively, professionals have a broad perception of prototypes. They identify a wider range of attributes, including prototypes as a communication tool, an aid in making decisions, and a way to learn about unknowns throughout the design process.

Many instructors in design education are cognizant of the importance of prototyping. However, we believe that students require explicit instruction about key concepts. It is not enough to just tell students to “prototype.” As design educators, we must be aware of the various roles of prototypes, and teach these concepts to students. We provide some immediate recommendations for practice, including a list of ten principles of prototypes to create similar mental models between students.
Effect of Body Posture on Comfort During Cycling
Authors: Polanco Alejandra P. , Suárez Daniel R. , Muñoz Luis E.
Published: November 2017

The purpose of this study was to analyze the influence of body posture on comfort during road cycling by implementing procedures that require only basic instrumentation. Static comfort and dynamic comfort were studied through experimental and computational approaches, respectively. For the experimental approach, subjective rating scales and an objective index proposed by the authors were used to assess static comfort. For the computational approach, a lumped-mass model with four degrees of freedom was implemented to compute the vertical acceleration of the bicycle and cyclist. The vertical acceleration was used to evaluate dynamic comfort according to ISO 2631. Body posture was determined from the handlebar-hands contact point and quantified in terms of the location of its center of mass and the location of the hands-handlebar contact point. Five postures were considered in the study.

For static comfort, correlation indexes of 0.941 and −0.913 were found between the cyclist’s center of mass location and the hands and buttocks static comfort, respectively. For dynamic comfort, a correlation index of −0.992 was found between dynamic comfort and the hands-handlebar contact point location. The results suggest correlations between the body posture and static and dynamic comfort.
Analysis of Sliding Mode Observers Using a Novel Time-Averaged Lyapunov Function
Authors: Mehta Sagar , Vijayaraghavan Krishna
Published: November 2017

Sliding mode observers are known to be robust to model uncertainties. However, sliding mode observers have not been well analyzed in the presence of Gaussian disturbances and no previous results exist for a pure sliding mode observer in the presence of sensor noise. A traditional quadratic Lyapunov function that is used to determine the stability of sliding mode observers, fails for noisy systems. Hence this paper introduces a novel Lyapunov candidate function termed the time averaged Lyapunov (TAL) function to analyze the stability of noisy systems. The TAL specifically examines the effect of the Gaussian noise on a sliding mode observer. Using this TAL function, the paper demonstrates that Gaussian sensor noise does not affect the stability or chatter of the observer. Further, the covariance of the noise only affects the convergence rate of the observer. Simulation results are reported to demonstrate the effectiveness of the proposed approach on a Linear system.
Handling Performance Improvement via Steering Reactive Torque Design Based on Integrated Driver-Vehicle Model
Authors: Cheng Shuai , Song Jian , Lu Zhenghong , Dong Wenlong
Published: November 2017

In some specific driving conditions, the steering behavior of the driver is significantly influenced by the reactive torque of the steering system. According to the vehicle dynamics, the steering angle along with the longitudinal velocity determines the vehicle states as well as the driving feeling. Thus, the steering reactive torque shows a remarkable influence on the evaluation of the lateral stability in high-speed condition. Given that the steady state gain increases with the velocity, this effect is especially significant in the high speed condition. As a result, the steering reactive torque must be designed to match the vehicle speed properly. However, except for simple experiential method, no normative design procedure of the reactive torque is proposed at present. In this paper, the influence of the steering reactive torque on the driver’s steering behavior is studied on the basis of the integrated neuromuscular system (NMS) vehicle model, which shows that a larger reactive torque could effectively restrain the unnecessary rapid steering operations and thus improve the handling performance of the vehicle. Key states of the vehicle dynamics is selected as the parameterized index of the physiological perception of the lateral stability. A novel design approach of the steering reactive torque is then proposed on the basis of the correlation of the reactive torque and the vehicle states. By introducing a new design principle — maintaining the physiological-perception-related dynamics states, the evaluation of the lateral stability can remain favorable despite the increasing speed. Effectiveness of the proposed design procedure is validated by a driving simulator and promising results have been obtained.
Bimaterial Micro-Structured Annulus With Zero Thermal Expansion Coefficient
Authors: Xie Yan , Lu Dengfeng , Yu Jingjun
Published: November 2017

This paper mainly concentrates on the design and analysis of the annulus with zero thermal expansion coefficient (ZTE) aiming to solve the heat generation and deformation in high speed bearing. First, a fork-like lattice cell inspired by the basic triangular cell is put forward and further applied to construct an annulus. The stretch-dominated lattice cell utilizes the Poisson’s contraction effect to achieve the tailorable thermal expansion coefficient (CTE). The thermal behaviors differences between the continuous interfaces and lattice cells will lead to the internal stress. Thus, the CTE of the annulus consisting of the lattice cell can be tailored to zero even negative values through the offset between the thermal-strain and force-strain. Then a theoretical model is established with some appropriate assumptions to reveal the quantitative relations among the geometrical parameters, material properties and equivalent CTEs thoroughly. The prerequisites for realizing a zero CTE are further derived in terms of material limitations and geometric constraints. Finally, FEA method is implemented to verify and analyze the thermal behaviors of annulus. The proposed annulus design characterized by the CTE tunability, structure efficiency and continuous interfaces is hopefully to be applied in the high speed bearings, adapters between the shaft and collar and fastener screws.
A Modular Method for Manufacturing Error Analysis of Linkages and Manipulators
Authors: Ting Kwun-Lon , Hsu Kuan-Lun , Wu Long-Iong , Wang Jun
Published: November 2017

This paper presents a simple and effective methodology to address the issues on the manufacturing error analysis and the tolerance design of linkages and manipulators. It assesses the effect of the dimension tolerances to the performance error and inversely determines the required dimensional tolerances for a prescribed performance tolerance. The methodology is adaptable to assess the effect of an individual tolerance as well as any combination of tolerances.

Instead of using complex closed loop equations to describe the linkage geometry, the methodology is focused on using linkage topology. Complex linkages are broken down to basic RR, PR, and RP units. The error and tolerance computation of complex linkages are reduced to repeatedly or alternatively using forward and inverse analysis of basic RR, PR, and RP units. The methodology is exemplified by simple and complex linkages.

For design and manufacturing engineers, the proposed method is most useful for quick tolerance allocation and performance error assessment.
A Framework for Energy-Based Kinetostatic Modeling of Compliant Mechanisms
Authors: Chen Guimin , Ma Fulei , Bai Ruiyu , Magleby Spencer P. , Howell Larry L.
Published: November 2017

Although energy-based methods have advantages over the Newtonian methods for kinetostatic modeling, the geometric nonlinearities inherent in deflections of compliant mechanisms preclude most of the energy-based theorems. Castigliano’s first theorem and the Crotti-Engesser theorem, which don’t require the problem being solved to be linear, are selected to construct the energy-based kinetostatic modeling framework for compliant mechanisms in this work. Utilization of these two theorems requires explicitly formulating the strain energy in terms of deflections and the complementary strain energy in terms of loads, which are derived based on the beam constraint model. The kinetostatic modeling of two compliant mechanisms are provided to demonstrate the effectiveness of using Castigliano’s first theorem and the Crotti-Engesser theorem with the explicit formulations in this framework. Future work will be focused on incorporating use of the principle of minimum strain energy and the principle of minimum complementary strain energy.
Interaction of Higher Modes in Nonlinear Free Vibration of Stiffened Rectangular Plates
Authors: Farhangdoust Saman , Younesian Davood , Esmailzadeh Ebrahim
Published: November 2017

Nonlinear free vibration analysis of stiffened plates is presented in this paper. The von Karman theory is employed to model the rectangular stiffened steel plate. The first two symmetric and asymmetric modes are taken into consideration and the coupled nonlinear differential equations of system are derived using the Galerkin approach. The Variational Iteration Method (VIM) is considered as the solution technique and an integral iterative formulation is presented to obtain the nonlinear natural frequencies. Subsequently a parametric sensitivity study is carried out and the effect of different initial amplitudes on the frequency responses is investigated.
The Snap-Through of Four-Fold Origami Cones
Authors: Pagano Alexander , Tawfick S.
Published: November 2017

Some insects, such as beetles, are able to store their wings under their elytra by folding them and can rapidly deploy their wings for flight. The crease patterns of these wings allow the fold/unfold kinematics to take place using simple manipulation, and to remain stable in both configurations. It has been observed that the structures of the beetle wings are kinetically multi-stable origami. The crease pattern of these wings is comprised of a peculiar arrangement of four-fold vertices. In this manuscript, we show preliminary work towards studying the non-flat (conical) four-fold vertices observed in the wing structure using experiments and rigid origami analysis. We construct four-fold origami paper cones of varying angles and study their snap-through behavior under varying point-load configurations. From these experiments, the threshold forces, displacements and duration timescale of snap-through buckling are extracted. Similarly, we study the snap-through instability of two-dimensional (2D) arches having a vertex, which provide insights into the wing folds and are hypothesized to represent properties which facilitate the deployability of the wing. Using the pseudo-rigid body model (PRBM) [1], we numerically analyze the kinematics and potential energy of the snap-though buckling of 2D arches, and show that the model captures the kinematic behavior sufficiently well to provide insights of energetic behavior from kinematic experimental results. Overall, our approach shows promise in studying the design and kinetics of the insect wing origami, and could enable the design of bio-inspired deployable engineering structures.
Enabling Cyber-Based Learning of Product Sustainability Assessment Using Unit Manufacturing Process Analysis
Authors: Raoufi Kamyar , Haapala Karl R. , Kremer Gül E. Okudan , Kim Kyoung-Yun , Psenka Carolyn E. , Jackson Kathy L.
Published: November 2017

Efforts to reduce product environmental impacts such as energy consumption and carbon footprint have received attention for many years, often driven by consumer pressure on companies to produce more environmentally friendly products. As the next generation of engineers who will take responsibility for advancing the sustainability of products, processes, and systems, engineering students need to become more familiar with the concepts of sustainable product design and manufacturing. Yet, educators are disadvantaged in training these students, and tools are deficient in assisting product sustainability assessments for manufacturing decision making by other non-experts. A manufacturing analysis module is introduced, which was developed under collaborative research titled, Constructionism in Learning: Sustainable Life Cycle Engineering (CooL:SLiCE). This CooL:SLiCE manufacturing analysis module provides an opportunity for non-expert students and engineers to investigate the impacts of product design changes on manufacturing processes and supply chain network configurations, e.g., selection of upstream processes, transportation routes, and transportation modes, from environmental responsibility perspective. One popular consumer product, a multicopter, is selected to demonstrate the module. The production of three hexacopter components are evaluated: the upper shell, lower shell, and propeller. The manufacturing analysis module enables non-experts to gain a better understanding of sustainable product design and manufacturing.
A Note on the Lyapunov Stability of Fractional-Order Nonlinear Systems
Authors: Dadras Sara , Dadras Soodeh , Malek Hadi , Chen YangQuan
Published: November 2017

In this paper, stability of fractional order (FO) systems is investigated in the sense of the Lyapunov stability theory. A new definition for exponential stability of the fractional order systems is given and sufficient conditions are obtained for the exponential stability of the FO systems using the notion of Lyapunov stability. Besides, a less conservative sufficient condition is derived for asymptotical stability of FO systems. The stability analysis is done in the time domain. Numerical examples are given to show that the obtained conditions are effective and applicable in practice.