bluuebunny/crossref_metadata_2025 huggingface dataset:
Algorithm for Multiple Time-Frequency Curve Extraction From Time-Frequency Representation of Vibration Signals for Bearing Fault Diagnosis Under Time-Varying Speed Conditions
Authors: Huang Huan , Baddour Natalie , Liang Ming
Published: November 2017

Bearing fault diagnosis under constant operational condition has been widely investigated. Monitoring the bearing vibration signal in the frequency domain is an effective approach to diagnose a bearing fault since each fault type has a specific Fault Characteristic Frequency (FCF). However, in real applications, bearings are often running under time-varying speed conditions which makes the signal non-stationary and the FCF time-varying. Order tracking is a commonly used method to resample the non-stationary signal to a stationary signal. However, the accuracy of order tracking is affected by many factors such as the precision of the measured shaft rotating speed and the interpolation methods used. Therefore, resampling-free methods are of interest for bearing fault diagnosis under time-varying speed conditions. With the development of Time-Frequency Representation (TFR) techniques, such as the Short-Time Fourier Transform (STFT) and wavelet transform, bearing fault characteristics can be shown in the time-frequency domain. However, for bearing fault diagnosis, instantaneous time-frequency characteristics, i.e. Time-Frequency (T-F) curves, have to be extracted from the TFR. In this paper, an algorithm for multiple T-F curve extraction is proposed based on a path-optimization approach to extract T-F curves from the TFR of the bearing vibration signal. The bearing fault can be diagnosed by matching the curves to the Instantaneous Fault Characteristic Frequency (IFCF) and its harmonics. The effectiveness of the proposed algorithm is validated by experimental data collected from a faulty bearing with an outer race fault and a faulty bearing with an inner race fault, respectively.
A Passive Ankle-Foot Prosthesis With Energy Return to Mimic Able-Bodied Gait
Authors: Holgate Robert , Sugar Thomas , Nash Audrey , Kianpour Jasper , Johnson Craig Trevor , Santos Edwin
Published: November 2017

It has been shown previously that for slow to normal walking speeds the ankle joint behaves similar to a passive mechanism from foot flat to push off. Thus a passive ankle mechanism was developed in order to mimic able-bodied gait in amputees. The ankle device is shown to be capable of matching the ground slope during heel strike, efficiently storing breaking energy from the user during rollover then releasing that energy to assist in push off, and raising the toe during swing phase to reset the system for the next heel strike. Mechanism functionality was verified through lab testing. Human testing was done through an ankle-bypass system on able-bodied subjects to verify device safety and functionality.
Eye Gaze Experiment Into the Recognition of Intended Affordances
Authors: Burlamaqui Leonardo , Dong Andy
Published: November 2017

An eye-tracking experiment aimed at testing the claim that individuals understand how to use artifacts through the visual perception of their intended affordances was conducted. Sixty-one participants were asked to state the manner in which they would interact with an artifact after looking at their screen-based images for ten seconds with their gaze captured. The participants’ responses to perceived affordance were compared to their gaze data. Although individuals identified plausible affordances, a binary logistic regression analysis was inconclusive as to which eye-tracking variable is likely to entail a successful identification of the intended affordance. That said, there was a strong relationship between perception of the intended affordance and mention of either the artifact’s function or semantic category. The results suggest that affordances may not have a significant impact in the usability of products and interfaces. Extrapolating from the findings, we postulate that analogical priming may be a better explanation for the way individuals understand what to do with the artifact.
Polyhedra Fabrication Through Mesh Convexification: A Study of Foldability of Nearly Convex Shapes
Authors: Xi Zhonghua , Lien Jyh-Ming
Published: November 2017

A polyhedron can be unfolded to a net, i.e., an unfolding without overlapping, by carefully cutting along the surface. If the cuts are restricted only on the edges of the polyhedron, where should the cuts be? This is called an edge-unfolding problem, which has been extensively studied in the literature for centuries. Although several promising properties have been discovered, several recent preliminary works show that no valid net exists even for certain simple non-convex polyhedra. Therefore, we propose to convexify the input polyhedron before unfolding. More specifically, we remove local concave surface features via inflation simulation. We then eliminate global concave structure features by segmenting the polyhedron to a small number of part-aware and nearly convex components. Then the net for each nearly convex component can be obtained. We further show that convexified shapes can be continuously folded and can be easily realized by a physical self-folding machine Our experimental results show that the proposed convexification approaches can reduce the computation time by several folds.
A DOE Approach for Evaluating the Effect of Bicycle Properties on Stability
Authors: Doria Alberto , Favaron Valerio , Roa Sergio
Published: November 2017

The effect on stability of mass, geometric and stiffness parameters of a bicycle with compliant frame, fork and wheel is studied. Critical stiffnesses of the structural elements are identified by means of specific experimental tests based on modal analysis and static stiffness measurement. Numerical stability analysis is carried out by means of a MATLAB code and simulations are planned with the design of experiment (DOE) approach. Numerical results show that the rigid body properties that have the main influence on self-stability are front wheel radius, longitudinal position of the center of mass and trail. Compliance of structural elements has a small effect on self-stability, but causes the appearance of a wobble mode that may be unstable at high speed.
Multi-Objective Decision Making of a Simplified Car Body Shape Towards Optimum Aerodynamic Performance
Authors: Song Kisun , Choo Kyung Hak , Kim Jung-Hyun , Mavris Dimitri N.
Published: November 2017

The importance of the aerodynamic performance, specifically meaning reducing both drag coefficient (CD) and lift coefficient (CL), is a growing issue in the modern automotive industry. The former is to improve fuel efficiency whereas the latter is to improve driving stability. These characteristics are quite associated with the geometric details of the external car body such that many studies are putting a lot of efforts to understand the contribution of geometrical details to the aerodynamic performance. For the design point of view, the comparison among local shape factors and the following trade-off study are essential during the early stage of the exterior design. In this paper, the qualitative and quantitative contribution of local shapes to overall aerodynamic performance is explored with a simplified vehicle model, especially the Ahmed body, by performing a multi-objective design optimization in a high-speed cruising condition. To achieve the goal of this research, Computational Fluid Dynamics (CFD) analysis is incorporated with various state-of-the-art design methodologies such as Design of Experiments (DOE), surrogate modeling, sensitivity analysis, Pareto-Optimum decision making, etc. Six design variables around the rear shapes of the Ahmed body are parameterized and populated into design space via a hybrid DOE method combining Central Composite Design (CCD) and Latin Hypercube. For CD and CL, corresponding Artificial Neural Networks (ANN) are created for the surrogate model. Then, the individual and collaborative contributions of design variables are scrutinized. For further detailed analysis, a Monte Carlo Simulation (MCS) is performed so that the empirical joint probability distribution is calculated to explore the feasible and optimum design space. Based on the simulation and analysis results, Pareto frontier is identified and multi-objective optimization is conducted to seek the best appropriate vehicle shapes for different design goals between CD and CL, which weigh on fuel efficiency and driving stability, respectively.
Reconfigurable 3-PRS Parallel Solar Tracking Stand
Authors: Yang Zhongxing , Zhang Dan
Published: November 2017

The solar tracking stand adjusts its pose timely to have the solar panel properly face to the moving sun. A 3-PRS parallel manipulator is designed that provides high stiffness and easy maintenance. The reconfiguration of the 3-PRS parallel stand allows further optimization of workspace and stiffness with respect to seasons. The research discusses an optimized design for green energy collection.
Kinematics, Workspace and Singularity Analysis of a Multi-Mode Parallel Robot
Authors: Chablat Damien , Kong Xianwen , Zhang Chengwei
Published: November 2017

A family of reconfigurable parallel robots can change motion modes by passing through constraint singularities by locking and releasing some passive joints of the robot. This paper is about the kinematics, the workspace and singularity analysis of a 3-PRPiR parallel robot involving lockable Pi and R (revolute) joints. Here a Pi joint may act as a 1-DOF planar parallelogram if its lockable P (prismatic) joint is locked or a 2-DOF RR serial chain if its lockable P joint is released. The operation modes of the robot include a 3T operation modes to three 2T1R operation modes with two different directions of the rotation axis of the moving platform. The inverse kinematics and forward kinematics of the robot in each operation modes are dealt with in detail. The workspace analysis of the robot allow us to know the regions of the workspace that the robot can reach in each operation mode. A prototype built at Heriot-Watt University is used to illustrate the results of this work.
Anisotropic, Adaptive, and Asymmetric Multi-Stability From Origami Folding
Authors: Li Suyi
Published: November 2017

This study investigates the elastic multi-stability properties originated from origami folding. Specifically, it focuses on a space-filling architecture consisting of stacked Miura-ori sheets, which exhibits multiple stable states corresponding to different internal folding configurations. The fundamentally three-dimensional shape transformations from origami folding impart several unique properties that are unachievable from the lower dimensional mechanisms. They are (1) anisotropy-arrangement of the stable and unstable states fundamentally differs along different principle axes; (2) adaptability-stable states can be generated or eliminated via simple pressurization; and (3) asymmetry-the energy barrier of switching from one stable state to another can be significantly higher than the opposite switch, even though the two stable states have the same energy level. These unique stability properties could be harnessed to create a wide variety of adaptive functionalities, such as programmable stiffness, impulsive actuation, and mechanical diode effect. The purpose of this paper is to examine the physical origin of the three stability properties and their correlations to the origami design. Results of this of study can foster the creation of novel multi-functional structures and materials based on origami.
Structural Shape Reconstruction of FBG Flexible Plate Using Modal Superposition Method
Authors: Li Li , Zhong Ben S. , Geng Zi Y. , Sun Wei
Published: November 2017

Structural shape reconstruction is a critical issue for real-time structural health monitoring in the fields of engineering application. This paper shows how to implement structural shape reconstruction using a small number of strain data measured by fiber Bragg grating (FBG) sensors. First, the basic theory of structural shape reconstruction is introduced using modal superposition method. A transformation is derived from the measured discrete strain data to global displacement field through modal coordinate, which is the same for strain mode shape superposition and displacement mode shape superposition. Then, optimization of the sensor layout is investigated to achieve the effective reconstruction effect. Finally, structural shape reconstruction algorithm using modal superposition method is applied in experiments. The experiment results show that the reconstructed displacements match well with those measured by a laser displacement sensor and the proposed approach is a promising method for structural shape reconstruction.
Analysis of Differential Mechanisms for a Robotic Head Stabilization System
Authors: Williams Adam , Saab Wael , Ben-Tzvi Pinhas
Published: November 2017

This paper presents a robotic system intended to help automate the head and neck stabilization process performed on trauma patients through application of a differential apparatus, a device that distributes an input between multiple output channels. A system to streamline the head stabilization process can save valuable time in a life and death scenario, as well as play a key role in future work on a mobile stretcher robot. This investigation focuses on finding the most suitable device to accommodate multiple possible head positions while maintaining a steady force in order to provide secure motion restriction. After an initial review of current emergency medical services standards, a comparison of potential differential mechanisms is undertaken. Static analysis as well as dynamic modeling is performed in order to determine the most appropriate mechanisms. An initial prototype design incorporating a differential pulley, the most mechanically advantageous mechanism, is then introduced.
A User Study on Exploring the Sequencing of Unit Cell Design Guidelines
Authors: Fazelpour Mohammad , Patel Apurva , Shankar Prabhu , Summers Joshua D.
Published: November 2017

The objective of this user study is to evaluate the effect of sequencing of unit cell design guidelines. The unit cell design guidelines support engineers in intentionally redesigning the topology and shape of unit cells for a desired structural behavior. In this study, four different unit cell design guidelines are selected to enable designers in increasing the shear flexure in meso-scale periodic cellular materials. These guidelines are not necessarily objective and may result in different modified unit cells when applied by different designers. Therefore, this user study was designed to evaluate the effect of sequencing the guidelines on the subjectivity and the modified unit cells. Twelve different sequencing sets are tested and it is found that certain sequencing of guidelines resulted in more novel ideas than other cases with less subjective guidelines.
Integration of Static Worst-Case Execution Time and Stack Usage Analysis for Embedded Systems Software in a Cloud-Based Development Environment
Authors: Hausladen Jürgen , Gerstmayer Florian , Jerabek Thomas , Horauer Martin
Published: November 2017

New applications relying on embedded systems technologies often come with an increased number of features and functionalities. For instance, improved safety, reliability, usability or reduced power consumption are commonly encountered aspects. Those in turn, however, come usually at the cost of increased complexity. Managing the latter can become challenging, especially when looking at (worst-case) execution times or memory usage of embedded systems. In particular, many applications, e.g., safety-critical or real-time applications, require knowledge about the worst-case execution time and stack usage to make a clear statement on important system parameters such as the overall performance or schedulability with regard to critical deadlines. Assessing these properties require elaborate tool support and profound knowledge and skills of the developers. In this paper, an evaluation of static analysis tools and the required steps to integrate these in a existing development environment is presented. The toolchain is either considered to be offline or deployed within a cloud-based integrated development environment. The cloud-approach enables ubiquitous access to the results and a unique visualization across multiple platforms. Additionally, the results are demonstrated along with a small use case.
Sequential Kriging Optimization for Time-Variant Reliability-Based Design Involving Stochastic Processes
Authors: Li Mingyang , Wang Zequn
Published: November 2017

This paper presents a sequential Kriging optimization approach (SKO) for time-variant reliability-based design optimization (tRBDO) with the consideration of stochastic processes. To handle the extremely high dimensionality associated with time-variant uncertainties, stochastic processes are transformed to random parameters through the equivalent stochastic transformation, leading to equivalent time-independent reliability models that are capable of capturing system failures over time. To alleviate computational burden, Kriging-based surrogate modeling is utilized to predict the response of engineered systems. It is further integrated with Monte Carlo simulation (MCS) to approximate the probability of failure. To reduce the epistemic uncertainty due to the lack of data, a maximum confidence enhancement method (MCE) is employed to iteratively identify important points for updating surrogate models. Sensitivities of reliability with respect to design variables are estimated using the first-order score function in the proposed tRBDO framework. Two case studies are introduced to demonstrate the efficiency and accuracy of the proposed approach.
Design of a Multi-Directional Hybrid-Locomotion Modular Robot With Feedforward Stability Control
Authors: Kumar Prashant , Saab Wael , Ben-Tzvi Pinhas
Published: November 2017

This paper presents the design of a modular robot capable of multi-directional mobility to aid reconfiguration on uneven terrain. Modular reconfigurable robotic systems consist of a large number of self-sufficient modules that can dock and reconfigure to scale locomotion and manipulation capabilities. However, on uneven terrains, reconfigurable robots face challenges due to the requirement of precise alignment between modules during the docking procedure. First, a survey of current modular reconfigurable robots is presented, analyzing their strengths and shortcomings in reconfiguration and mobility. A novel design is formulated that features a hybrid combination of wheels and tracks, symmetrically assembled about the front and right planes, providing multi-directional mobility and modularity. The robot can move over uneven terrain via tracks, move at higher speeds via wheels placed orthogonally to the tracks, and move in the vertical direction via a vertical translation mechanism in order to aid in multi-robot docking. Both the wheels and tracks possess yaw mobility via differential drive. The design’s compact size and hybrid multi-directional mobility system make the robot highly mobile on uneven terrain. Presented in this paper are the mechanical and electrical design and a feedforward dynamic stability controller, the performance of which is validated using a simulated case study.
Three-Dimensional Biomimetic Biosensors for Food Safety Applications
Authors: Huffman Brian , Mazrouei Roya , Bevelheimer Joseph , Shavezipur Mohammad
Published: November 2017

Three-dimensional biomimetic biosensors for food safety applications are presented. The sensors mimic the porous media of fresh produce and can detect the presence of pathogens in low concentration, monitor their internalization, and also determine potential formation of biofilm. The sensors use capacitive/impedance measurement for detection and have 3-dimensional structures allowing microorganisms to occupy the space between electrodes and the substrate. Interdigitated sensors with suspended electrodes and a parallel-plate sensor are studied using finite element analysis, and their performance is compared to that of a 2-imensional planar sensor. The simulation results show that under similar circumstances, all 3D sensors provide better sensitivities for detection of microorganisms and biofilm formation compared to the 2D sensor. 3D interdigitated and parallel-plate sensors display 16% and 30% higher sensitivity in detection of microorganisms, and 44% and 48% higher sensitivity for detection of biofilm formation, respectively. Furthermore, a biomimetic device with stack of electrodes is presented that can monitor the internalization of pathogens in real time. The device forms layers of multiple sensors resembling the actual fresh produce and can track the penetration of microorganisms inside the device. This novel structure allows us to understand how long it takes for microorganisms to penetrate in a produce and how environmental parameters such as temperature variation or the presence of nutrients or sanitizers affect their behavior, providing invaluable data to improve food safety and optimize the sanitization processes.
Design Heuristics: A Conceptual Framework and Preliminary Method for Extraction
Authors: Lee Bumsoo , Fillingim Kenton B. , Binder William R. , Fu Katherine , Paredis Christiaan J. J.
Published: November 2017

In designing complex systems, systems engineers strive to turn an existing situation into a situation that is most preferred. A rational decision maker would choose the alternative that maximizes the expected utility of the existing situation, but there are significant computational challenges to this approach. To overcome these challenges, most decision makers revert to heuristics. In this paper, we propose a conceptual framework for heuristics in design. A preliminary empirical study of designers for a robotics design problem was conducted to observe how participants apply heuristics. Participants having at least 2 years of experience designing robots were recruited to partake in a robotics design session in which participant were given 45 minutes to work on a design problem. A preliminary heuristics extraction method was developed, and the identified heuristics were studied to find trends within the overall set. These trends were the basis of a taxonomy of heuristics consisting of three initial classification methods: design phase, field of study, and action intent. The heuristics and classifications are presented, along with the challenges from extracting heuristics and recommendations for future work to further research design heuristics and to improve the method for extraction.
A Comparison of Variety Metrics in Engineering Design
Authors: Henderson Daniel , Helm Kevin , Jablokow Kathryn , McKilligan Seda , Daly Shanna , Silk Eli
Published: November 2017

This paper focuses on comparing and contrasting methods for assessing the variety of a group of design ideas. Variety is an important attribute of design ideas, because it indicates the extent to which the solution space has been explored. There is a greater likelihood of successfully solving a design problem when a more diverse set of ideas is generated in the early stages of design. While there are three existing metrics for variety, it has not been established how well they correlate with each other, so it is unknown whether they provide similar assessments of variety. This uncertainty inspired our investigation of the three existing metrics and, eventually, the development of a new variety metric — all of which we compared statistically and qualitatively. In particular, 104 design ideas collected from 29 sophomore mechanical engineering students were analyzed using the existing and new variety metrics. We conducted correlation analyses to determine if the four metrics were related and to what degree. We also considered the qualitative differences among these metrics, along with where they might be used most effectively. We found varying levels of statistically significant correlations among the four metrics, indicating that they are dependent. Even so, each metric offers a unique perspective on variety and may be useful in different situations.
3D Printed Electronics: Opportunities and Challenges From Case Studies
Authors: Song Yu , Boekraad Roy A. , Roussos Lampros , Kooijman Adrie , Wang Charlie C. L. , Geraedts Jo M. P.
Published: November 2017

3D printed electronics introduces new opportunities in product design. On the other side, it also brings challenges regarding many aspects in the design and manufacturing process of prototypes/products. In this paper, based on our preliminary investigations, we summarize the opportunities of using 3D printed electronics in product design as: 1) it offers designers more freedom in their designs; 2) it promotes miniaturization of design; 3) it accelerates the design and manufacturing process; 4) it is able to improve the efficiency of producing customized/personalized mechatronic/electronic products and 5) it improves the sustainability in the product design and manufacturing process. Motivated by those opportunities, we conducted four case studies regarding four key aspects of 3D printed electronics: the conductive materials, geometric modelling, multiphysics simulation and manufacturing tools. Based on the findings in those case studies, we identified the challenges in 3D printed electronics and highlight the future works which may provide a better support to the needs of product designers.
Functional Design and Optimization of a Novel 3-URU Multimodal Reconfigurable Robot
Authors: Carbonari Luca , Corinaldi David , Palpacelli Matteo-Claudio , Palmieri Giacomo , Callegari Massimo
Published: November 2017

This paper presents the functional design and dynamics optimization of a reconfigurable 3-DoF parallel kinematics manipulator conceived for motions of pure rotations and pure translations. The main peculiarity of the device, indeed, is that of allowing changes of the mobility of its moving platform. The kinematic structure of the three identical legs is designed in a way that, when a particular configuration of the manipulator is reached, the transition between the working modes is possible through the reconfiguration of three metamorphic universal joints, which are used to connect each limb to the ground. This configuration allows to limit the weight of the moving bodies of the robot, with a consequent enhancement of the dynamic performance. The kinematics of the parallel robot is introduced in the very first part of the work as a necessary preamble to the optimization of the manipulator geometry, which has been performed in two steps: at first, the Jacobian matrices which characterize the two working modes were used as performance indices for the preliminary functional optimization of the device; subsequently, an optimization of the dynamic behaviour was performed to obtain a complete characterization of the robot in both its modes.
Towards Optimizing DC Loads for Power Generation From Arbitrarily Excited Nonlinear Vibration Energy Harvesters
Authors: Dai Quanqi , Harne Ryan L.
Published: November 2017

In order to effectively take advantage of stiffness nonlinearities in vibration energy harvesters, the harvesters must be appropriately designed to ensure optimum direct current (DC) power generation. Yet, such optimization has only previously been investigated for alternating current (AC) power generation although most electronics demand DC power for their functioning. Moreover, real world excitations contain stochastic contributions combined with periodic components that challenges conventional approaches of investigation that only give attention to the harmonic excitation parts. To fill in the knowledge gap, this research undertakes comprehensive simulations to begin formulating conclusive understanding on the relationships between rectified power generation and nonlinear energy harvester system characteristics when the platforms are subjected to realistic combinations of harmonic and stochastic excitations. According to the simulation results, the rectified power demonstrates clear dependence on the load resistance in the unique limiting cases of complete or no stochastic excitation. When the excitation vibrations include both harmonic and stochastic components, the optimal resistance to maximize DC power exhibits a smoothly correlated but nonlinear change between the limiting case values of the resistance. The results of this investigation provide direct evidence of the intricate relationships among peak DC power, optimal resistive loads, and the nonlinear energy harvester design, and encourage continued study for direct analytical expressions that define such relationships.
Computational Characterization of Double Porosity Metamaterials for Broadband Sound Insulation
Authors: Cui Shichao , Harne Ryan L.
Published: November 2017

This research investigates the sound insulation properties — sound absorption coefficient and transmission loss — of a double porosity metamaterial and the functional dependence of such properties on the selection of underlying poroelastic material. The internal metamaterial geometry enables a global rotation phenomenon when the system is under a static compression. Using the finite element method, the influence of such compression upon the acoustic properties is quantified for its role in enhancing and tailoring sound insulation characteristics, while the additional influence of embedded rigid inclusions is examined. By applying these concepts to metamaterials composed from different poroelastic media, it is found that the acoustic properties can be tuned over strategic frequency ranges of relevance for sound insulation. In particular, the results demonstrate that for certain metamaterial compositions the absorption coefficient can be increased by about 100% and the transmission loss enhanced by 20% across a broad range of low frequencies by the introduction of the inclusions, while the compression constraint can increase the properties by 10 to 20% across narrow frequency bands. The outcomes suggest new possibilities for greatly enhancing the acoustic insulation properties of poroelastic materials in applications where space is limited and/or where added mass is not a concern.
Periodic Motions in a Coupled Van Der Pol-Duffing Oscillator
Authors: Xu Yeyin , Luo Albert C. J.
Published: November 2017

In this paper, periodic motions of a periodically forced, coupled van der Pol-Duffing oscillator are predicted analytically. The coupled van der Pol-Duffing oscillator is discretized for the discrete mapping. The periodic motions in such a coupled van der Pol-Duffing oscillator are obtained from specified mapping structures, and the corresponding stability and bifurcation analysis are carried out by eigenvalue analysis. Based on the analytical prediction, the initial conditions of periodic motions are used for numerical simulations.
Realtime Power Management of a Multi-Source HEV Using Adaptive Dynamic Programing and Probabilistic Drive State Model
Authors: M. Ali Ahmed , Söffker Dirk
Published: November 2017

Power management in multi-source hybrid electric vehicles (HEVs) is a nontrivial problem dealing with different forms of energy. Optimal-based approaches are not facile to apply in realtime due to their high computational requirements. Rule-based (RB) algorithms are suitable for realtime control; however, the solution provided is non-optimal. Development of applicable optimal-based solution in realtime control can ensure higher efficiency of HEVs. This paper presents a new method for realtime optimal control of multisource HEVs using adaptive dynamic programming (ADP). The developed concept is based on drive state recognition in terms of physics-based parameters. Vehicle operating conditions are offline optimized for each state using NSGA-II optimization tool. The optimized solution can be applied state-wise in realtime using adaptive RB method. To apply ADP, probabilistic drive state model is developed to provide a lookahead window and generate state transition network for the specified horizon. The algorithm is customized in terms of prediction stepsize/length to solve the shortest path problem in realtime. Experimental application is conducted using emulation test-rig to validate the results. Both simulation and experimental results show reduction of total cost function in terms of fuel consumption and on-board charge sustaining.
A Goal-Oriented, Inverse Decision-Based Design Method to Achieve the Vertical and Horizontal Integration of Models in a Hot Rod Rolling Process Chain
Authors: Nellippallil Anand Balu , Rangaraj Vignesh , Gautham B. P. , Singh Amarendra Kumar , Allen Janet K. , Mistree Farrokh
Published: November 2017

Reducing the manufacturing and marketing time of products by means of integrated simulation-based design and development of the material, product, and the associated manufacturing processes is the need of the hour for industry. This requires the design of materials to targeted performance goals through bottom-up and top-down modeling and simulation practices that enables handshakes between modelers and designers along the entire product realization process. Manufacturing a product involves a host of unit operations and the final properties of the manufactured product depends on the processing steps carried out at each of these unit operations. In order to effectively couple the material processing-structure-property-performance spaces, there needs to be an interplay of the systems-based design of materials with enhancement of models of various unit operations through multiscale modeling methodologies and integration of these models at different length scales (vertical integration). This ensures the flow of information from one unit operation to another thereby establishing the integration of manufacturing processes (horizontal integration). Together these types of integration will support the decision-based design of the manufacturing process chain so as to realize the end product.

In this paper, we present a goal-oriented, inverse decision-based design method to achieve the vertical and horizontal integration of models for the hot rolling and cooling stages of the steel manufacturing process chain for the production of a rod with defined properties. The primary mathematical construct used for the method presented is the compromise Decision Support Problem (cDSP) supported by the proposed Concept Exploration Framework (CEF) to generate satisficing solutions under uncertainty. The efficacy of the method is illustrated by exploring the design space for the microstructure after cooling that satisfies the requirements identified by the end mechanical properties of the product. The design decisions made are then communicated in an inverse manner to carry out the design exploration of the cooling stage to identify the design set points for cooling that satisfies the new target microstructure requirements identified. Specific requirements such as managing the banded microstructure to minimize distortion in forged gear blanks are considered in the problem. The proposed method is generic and we plan to extend the work by carrying out the integrated decision-based design exploration of rolling and reheating stages that precede to realize the end product.
Effect of Implicitly Derived Infill Patterns on Mechanical Properties
Authors: Adams Davis W. , Turner Cameron J.
Published: November 2017

One of the most important steps in the preprocessing stage of fused deposition modeling is the generation of a set of instructions that control every movement of the tool head, known as GCode, which is created by a slicer software. The tool path is dependent on various user defined inputs including infill pattern, infill density, layer height, and feed rate. All current slicers generate the path explicitly and do not consider certain geometries that will create critical voids such as thin walls and small corners. This work replicates a new implicit slicing method in which functionally derived infill patterns are overlaid onto each layer of a part reducing the possibility of voids and flaws. Further research investigating the effects of varying implicit infill patterns have on mechanical properties is also included. Stress and strain data is gathered for three different test cases, and the resulting mechanical properties for each case are compared.
Design and Preliminary Evaluation of a Powered Pediatric Lower Limb Orthosis
Authors: Laubscher Curt A. , Farris Ryan J. , Sawicki Jerzy T.
Published: November 2017

This paper describes the first stages of hardware development and preliminary assessment for a powered lower limb orthosis designed to provide gait assistance and rehabilitation to children with walking impairments, such as those associated with cerebral palsy and spina bifida. The design requirements, including range of motion, speeds, torques, and powers, are investigated and presented based on a target user age range of 6–11 years old. A three stage joint actuator is designed, built, and tested against the design requirements. The 0.6 kg actuator produced 4.2 Nm continuous torque and 17.2 Nm peak torque, and was able to run up to a speed of 480 deg/s. Backdrivability was characterized in terms of rotational friction, which was measured at 1.1 Nm. Finally, a 5.1 kg prototype orthosis was developed consisting of a hip segment, left and right thigh segments, and left and right shank segments, with four identical actuator prototypes installed in the thigh segments to actuate the hips and knees. Control electronics and a basic control structure were implemented to test the joint tracking capability of the orthosis against a predefined set of trajectories which were representative of pediatric gait patterns. Fitted to a dummy, the controlled limb successfully tracked the desired trajectories with a root-mean-square error of 9% and 4% of full scale for the hips and knees, respectively. With the dummy loaded with additional weight to representing a 32 kg child, the limbs also successfully tracked the trajectories with a root-mean-square error of 15% and 6% of full scale for the hips and knees, respectively.
Motor Skill Evaluation During Robot-Assisted Surgery
Authors: Shafiei Somayeh B. , Cavuoto Lora , Guru Khurshid A.
Published: November 2017

Remote manipulation during robot-assisted surgery requires proficiency in perception, cognition, and motor skills. We aim to understand human motor control in remote manipulation of robotic surgical instrument and attempt to measure motor skills. Three features, smoothness, normalized jerk score, and two-thirds power law coefficient, estimating the motor skills of surgeons were analyzed. These features were calculated through segments, extracted from continuous end-effector trajectories during suturing, knot-tying, and needle-passing surgical tasks, performed by 8 right-handed subjects on bench-top models using da vinci surgical kit control system. Each subject repeated each task five times. Totally 1567 segments were extracted, 413, 437, and 717 segments performed by experts, intermediates, and novice subjects, respectively. Dynamic change of kinematic properties was analyzed to evaluate the relationship between considered features and motor skill level. Results show smoothness is significantly correlated with normalized jerk score and both features are significant measures of expertise levels. Also, results show the power law is violated by many end-effector trajectories and there is no relationship between obeying two-thirds power law, smoothness and jerk. We conclude trajectory is improved from non-smooth and jerky in novices to smooth in expert surgeons. This property may be used for motor skill evaluation. It is unlikely that obeying two-thirds power law be a valid property of all end-effector trajectories. However, power law coefficient may be a discriminant feature for levels of expertise. The results are also applicable in a home-based monitoring platform, to monitor motor functioning improvement of stroke patients during rehabilitation process.
Unified Scaling of Dynamic Optimization Design Formulations
Authors: Herber Daniel R. , Allison James T.
Published: November 2017

In this article, we explore scaling in dynamic optimization with a particular focus on how to leverage scaling in design studies. Here scaling refers to the process of suitable change of variables and algebraic manipulations to arrive at equivalent forms. The necessary theory for scaling dynamic optimization formulations is presented and a number of motivating examples are shown. The presented method is particularly useful for combined physical-system and control-system design problems to better understand the relationships between the optimal plant and controller designs. In one of the examples, scaling is used to understand observed results from more complete, higher-fidelity design study. The simpler scaled optimization problem and dimensionless variables provide a number of insights. Scaling can be used to help facilitate finding accurate, generalizable, and intuitive information. The unique structure of dynamic optimization suggests that scaling can be utilized in novel ways to provide better analysis and formulations more favorable for efficiently generating solutions. The mechanics of scaling are fairly straightforward but proper utilization of scaling is heavily reliant on the creativity and intuition of the designer. The combination of existing theory and novel examples provides a fresh perspective on this classical topic in the context of dynamic optimization design formulations.
Analysis of Drilling Process Knowledge Derived From Microdrill Catalog Database Using Data-Mining Method
Authors: Tabata Shogo , Aoyama Eiichi , Hirogaki Toshiki , Kodama Hiroyuki
Published: November 2017

As electronic devices and products are being miniaturized, the printed wiring boards (PWBs) within them are also being miniaturized. Therefore, it is becoming increasingly difficult to decide the drilling conditions required for producing small-diameter and high-density holes. We have been focusing on drilling conditions recommended in drill catalogs and have been attempting to gather knowledge that drilling experts use to decide the drilling conditions. In this study, we classify drills using the relationship between the diameter and the flute length and hence show that the methods used for setting the cutting conditions are different in different regions of a PWB. In addition, by using a catalog of microdrills that use alloy steel as the work material, we discuss how unique drilling conditions can be set for PWBs.
On the Controllability of Distributed-Order Fractional Systems With Distributed Delays
Authors: He Bin-Bin , Chen YangQuan , Kou Chun-Hai
Published: November 2017

This paper investigates the controllability of distributed-order fractional systems with distributed delays. By using the controllability Gramian matrix and reduction to absurdity, a necessary and sufficient condition for the controllability of linear system is established, and a sufficient condition for the nonlinear system is obtained. Examples are given to illustrate the effectiveness of the theorems.
Scenario-Based Conjoint Analysis: Measuring Preferences for User Experiences in Early Stage Design
Authors: Kim Hyeji , Chen Jing , Kim Euiyoung , Agogino Alice M.
Published: November 2017

Conjoint analysis has proven to be a useful method for decomposing and estimating consumer preference for each attribute of a product or service through evaluations of sets of different versions of the product with varying attribute levels. The predictive value of conjoint analysis is confounded, however, by increasing market uncertainties and changes in user expectations. We explore the use of scenario-based conjoint analysis in order to complement qualitative design research methods in the early stages of concept development. The proposed methodology focuses on quantitatively assessing user experiences rather than product features to create experience-driven products, especially in cases in which the technology is advancing beyond consumer familiarity. Rather than replace conventional conjoint analysis for feature selection near the end of the product development cycle, our method broadens the scope of conjoint analysis so that this powerful measurement technique can be applied in the early stage of design to complement qualitative research and drive strategic directions for developing product experiences. We illustrate on a new product development case study of a flexible wearable for parent-child communication and tracking as an example of scenario-based conjoint analysis implementation. The results, limitations, and findings are discussed in more depth followed by future research directions.
Environmental Sustainability Awareness in Product Design Practices: A Survey of Italian Companies
Authors: Favi Claudio , Germani Michele , Gregori Fabio , Mandolini Marco , Marconi Marco , Marilungo Eugenia , Papetti Alessandra , Rossi Marta
Published: November 2017

This paper aims to analyze the attitude and the awareness of environmental sustainability issues within diverse Italian industrial companies. A survey has involved a balanced sample of companies operating in different industrial sectors. Considering the survey’s results it can be concluded that: (i) environmental sustainability is an opportunity and a current market requirement, (ii) environmental sustainability is not formalized, since specific methods and tools are not used in technical departments, and (iii) environmental decisions are mainly made by specific key figures (i.e. energy/environmental manager). This analysis can be considered as a useful starting point for the framework formalization of eco-design approaches and tools able to bring eco-design principles into the work of technical departments with the aim to foster the future development of green and sustainable products and services.
Hysteresis Effect in the Nonlinear Stability of Towed Wheels
Authors: Beregi Sándor , Takács Dénes , Barton David A. W.
Published: November 2017

In this paper the dynamics of towed elastic wheels are studied with the help of the brush tyre model. To calculate the lateral deformation of the contact patch centre-line distributed time-delay is taken into account for the rolling parts, whereas parabolic limits are used to determine the deformation in case of side-slip. After linear stability analysis of the rectilinear motion the limit cycles of the non-smooth time-delayed system are calculated with the method of numerical collocation. With the help of bifurcation diagrams it is demonstrated how the periodic orbits develop from the linear stability boundary in a structure characteristic of piecewise-smooth systems. Moreover, it is shown that the contact memory effect and the dry friction yield bistable parameter ranges besides the linearly unstable domains. Namely, for one particular towing velocity a stable equilibrium corresponding to straight-line motion and a stable periodic orbit coexist resulting a hysteresis effect in the stability of the straight-line motion.
A Fast Finite Element Based Methodology to Predict the Temperature Field in a Thermoplastic Spur Gear Drive
Authors: Roda-Casanova V. , Sanchez-Marin F. , Porras-Vazquez A.
Published: November 2017

Plastic gears bring some interesting advantages compared to metal gears. However, they also have some drawbacks, many of them related to the dependency of their mechanical properties with the temperature. Among other reasons, the friction between the gear teeth causes a heat flux that heats the gears and produces temperature variations within the gear geometries. These temperature variations have effects on the mechanical response of the gears, that must be taken into account when designing plastic gear drives.

In this work, two different finite element models have been proposed to perform heating contact analysis, that is a coupled thermal-stress analysis that takes into account the heating produced by friction and the non-linear properties of the material. As a result of these models, the temperature field of the gears can be determined at any running time, as well as other interesting results, such as the transmission error function or the instantaneous power loss.