bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Performance Analysis of Robust H∞ Controller for a Scaled Autonomous Multi-Wheeled Combat Vehicle Heading Control
Authors: Mohamed Amr , El-Gindy Moustafa , Ren Jing
Published: November 2018

This paper describes the design of a H∞ controller to track the desired heading angle for a scaled multi-wheeled combat vehicle considering the uncertainties that are difficult to estimate such as noise and disturbance. The augmented plant is structured by adjusting the weighting functions in presence of noise and disturbance. The developed H∞ framework is well suited for controlling the steering of the vehicle’s front four wheels individually to obtain the correct heading angle. The vehicle simulations are carried out and the robustness of the proposed heading angle tracking algorithm is incorporated. It has been found that the vehicle controller has the capability to achieve the desired heading angle changes with good performances and efficiency.
A Hybrid Symbolic-Numeric Computational Method for Analysis of Bilinear Systems
Authors: Tien Meng-Hsuan , D’Souza Kiran
Published: November 2018

In this paper, an efficient and accurate computational method for determining responses of high-dimensional bilinear systems is developed. Predicting the dynamics of bilinear systems is computationally challenging since the piecewise-linear nonlinearity induced by contact eliminates the use of efficient linear analysis techniques. The new method, which is referred to as the hybrid symbolic-numeric computational (HSNC) method, is based on the idea that the entire nonlinear response of a bilinear system can be constructed by combining linear responses in each time interval where the system behaves linearly. The linear response in each time interval can be symbolically expressed in terms of the initial conditions. The transition time where the system switches from one linear state to the other and the displacement and velocity at the instant of transition are solved using a numerical scheme. The entire nonlinear response can then be obtained by joining each piece of the linear response together at the transition time points. The HSNC method is based on using linear features to obtain large computational savings. Both the transient and steady-state response of bilinear systems can be computed using the HSNC method. Thus, nonlinear characteristics, such as subharmonic motion, bifurcation, chaos, and multistability, can be efficiently analyzed using the HSNC method. The HSNC method is demonstrated on a single degree of freedom system and a cracked cantilever beam model, and the nonlinear characteristics of these systems are examined.
Automatic Postprocessing of Topology Optimization Solutions by Using Support Vector Machines
Authors: Strömberg Niclas
Published: November 2018

The postprocessing step from the density result in topology optimization to a parametric CAD model is typically most time consuming and usually involves several hands on maneuvers by an engineer. In this paper we propose an approach in order to automate this step by using soft non-linear support vector machines (SVM). Our idea is to generate the boundaries separating regions of material (elements with densities equal to one) and no material (elements with densities equal zero) obtained from topology optimization automatically by using SVM. The hyper-surface of the SVM can then in the long run be explicitly implemented in any CAD software. In this work we generate these hypersurfaces by solving the dual formulation of the SVM with soft penalization and nonlinear kernel functions using quadratic programming or the sequential minimal optimization approach. The proposed SVM-based postprocessing approach is studied on topology optimization results of orthotropic elastic design domains with mortar contact conditions studied most recently in a previous work. The potential energy of several bodies with nonmatching meshes is maximized. In such manner no extra adjoint equation is needed. Intermediate density values are penalized using SIMP or RAMP, and the regularization is obtained by applying sensitivity or density filters following the approaches of Sigmund and Bourdin. The study demonstrates that the SVM-based postprocessing approach automatically generates proper hypersurfaces which can be used efficiently in the CAD modelling.
Dynamic Stability of Parallel Manipulator at its Singularities Corresponding to Kinematic Parameters of Dynamic Systems
Authors: Yu-Tong Li , Yu-Xin Wang
Published: November 2018

With the aid of the Liyapunov first approximate stability criterion, the dynamic stability condition for the 3-RPR parallel mechanism to realize a deterministic motion at singular configurations is deduced. Based on this condition, the distributions of the kinematic parameters including input velocities and accelerations of the system corresponding to the stable motion at its singular configuration are investigated then. It is found that for a given singular configuration, increasing input velocities and accelerations, the sub-distributions of eigenvalues with positive real parts have a tendency to shrink and, consequently, the motion stability at the singular configuration can be enhanced; adjusting input velocities and accelerations only can not necessarily get all negative real parts of the eigenvalues sharing a common intersection of the distributing subintervals and, normally, the additional adjustment of initial velocities of the particle system should be added. Besides, while the movable platform goes through the singular configuration, if the control law of the input parameters makes the instantaneous velocity center of the movable platform far away from the singular point, the platform is able to go through the singular configuration with high stability and strong capability to resist external disturbances. This research indicates the effectiveness to improve the motion stability of the dynamics system at singular configurations via adjusting the input kinematic parameters. From this, a singularity-free approach via adjusting the input kinematic parameters can be utilized to exclude singularities of parallel mechanisms dynamically in the joint trajectory planning stage without introducing either redundancy or active mass.
Simulation Based Trajectory Analysis for the Tilt Controlled High Speed Narrow Track Three Wheeler Vehicle
Authors: Sindha Jigneshsinh , Chakraborty Basab , Chakravarty Debashish
Published: November 2018

Small sized three wheeler electric vehicles (EVs) are gaining popularity in many developing countries because of its low cost operation and excellent manoeuvrability. However, usage of such a 3Ws usage is limited to low speed application such as last mile public transport. Vehicles with such configuration are not well accepted for personal mobility. If the safe speed of such a vehicles are improved, such a vehicles can also become viable to personal transport. Active tilt control (ATC) systems are seen as one of the possible solution to improve safe speed of narrow track 3Ws.Literature indicates that many attempts have been made for establishing active tilt control system on 3W vehicles for enhancing stability of ATC vehicles and promising results were obtained. This paper presents simulation based analysis of the ATC 3W electric vehicle. This work is part of full scale experimental prototype development for the narrow track ATC 3W vehicle with one wheel in front configuration. The primarily focus of this work is to address vehicle dynamics and trajectory related issue of the tilting 3Ws.

A multi-body model of ATC 3W vehicle using single track lateral dynamic model with nonlinear tire characteristics was prepared in SimMechanics. The lateral dynamic outputs in terms of the trajectory followed by vehicle were compared for the constant steering inputs given to non-tilting vehicle, tilting vehicle with direct tilt control (DTC) system and tilting vehicle with Steering direct tilt control (SDTC) system. Two critical driving scenarios of U-turn and Lane change manoeuvre are analyzed. It is observed from the results that there is certain trade-off in selecting a tilt actuator and controller so as to minimize the jerks in the perceived acceleration due to high gain and minimize the tilt angle error to ensure proper stability improvement. It is also identified that the controller must be tuned to the predictable trajectory control, in addition to the main task of reducing the load transfer across the rear wheel axle. The model presented in the paper is used to understand the performance of DTC and SDTC control strategies during potentially dangerous manoeuvres. The desired path following ability of the vehicle is the main measures considered for the analysis.
Increasing Energy Efficiency of High-Speed Parallel Robots by Using Variable Stiffness Springs and Optimal Motion Generation
Authors: Balderas Hill Rafael , Briot Sébastien , Chriette Abdelhamid , Martinet Philippe
Published: November 2018

The classical approach to decrease the energy consumption of high-speed robots is by lowering the moving elements mass in order to have a lightweight structure. Even if this allows reducing the energy consumed, the lightweight architecture affects the robot stiffness, worsening the accuracy of the mechanism. Recently, variable stiffness actuators (VSAs) have been used in order to reduce the energy consumption of high-speed pick-and-place robots. The idea is to smartly tune online the stiffness of VSA springs so that the robot is put in near a resonance mode, thus considerably decreasing the energy consumption during fast pseudo-periodic pick-and-place motions. However, the serial configuration of springs and motors in the VSA leads to uncontrolled robot deflections at high-speeds and, thus, to a poor positioning accuracy of its end-effector.

In order to avoid these drawbacks and to increase the energy efficiency while ensuring the accuracy, this paper proposes the use of parallel arrangement of variable stiffness springs (VSS) and motors, combined with an energy-based optimal trajectory planner. The VSS are used as energy storage for carrying out the reduction of the energy consumption and their parallel configuration with the motors ensure the load balancing at high-speed without losing the accuracy of the robot. Simulations of the suggested approach on a five-bar mechanism are performed and show the increase on energy efficiency.
Comprehensive Simulation Model of a High Pressure Variable Displacement Vane Pump for Industrial Applications
Authors: Rundo Massimo , Pavanetto Michele A.
Published: November 2018

This paper deals with the hydraulic model of a high pressure variable displacement vane pump for industrial applications. The simulation is based on a 0D model implemented in the Amesim® environment with customized libraries. The geometry of the pump is described analytically or numerically and different leakage passageways are taken into account. The evaluation of some critical parameters was performed by means of 3D simulations. A finite element analysis allowed determining the deformation of the port plate for correcting the current axial clearances. A CFD analysis was performed for the evaluation of the discharge coefficients in the valves of the displacement control. The model was validated experimentally in terms of steady-state flow-pressure characteristics and of displacement control dynamics.
Vibrational Analysis of Human Femur Bone
Authors: Sadeghi Reza , Bakhtiari-Nejad Firooz , Goudarzi Taha
Published: November 2018

Femur bone is the longest and largest bone in the human skeleton. This bone connects the pelvic bone to the knee and carries most of the body weight. The static behavior of femur bone has been a center of investigation for many years while little attention has been given to its dynamic and vibrational behavior, which is of great importance in sports activities, car crashes and elderly falls. Investigation of natural frequencies and mode shapes of bone structures are important to understand the dynamic and vibrating behaviors. Vibrational analysis of femoral bones is presented using finite element method. In the analysis, the bone was modeled with isotropic and orthotropic mechanical properties. The effect of surrounding bone muscles has also been accounted for as a viscoelastic medium embedding the femur bone. Natural frequencies extracted considering the effects of age aggravated by weakening the elastic modulus and density loss. The effects of real complex bone geometry on natural frequencies are studied and are compared with a simple circular cross-sectional model.
A Single-Loop 7R Spatial Mechanism That Has Three Motion Modes With the Same Instantaneous DOF but Different Finite DOF
Authors: Kong Xianwen , Müller Andreas
Published: November 2018

Multi-mode mechanisms, including kinematotropic mechanisms, are a class of reconfigurable mechanisms that can switch motion modes with the same or different DOF (degree-of-freedom). For most of the multi-mode mechanisms reported in the literature, the instantaneous (or differential) DOF and finite DOF in a motion mode are equal. In this paper, we will discuss the construction, reconfiguration analysis, and higher-order mobility analysis of a multi-mode single-loop 7R mechanism that has three motion modes with the same instantaneous DOF but different finite DOF. Firstly, the novel multi-mode single-loop 7R spatial mechanism is constructed by inserting one revolute (R) joint into a plane symmetric Bennett joint-based 6R mechanism for circular translation. The reconfiguration analysis is then carried out in the configuration space by solving a set of kinematic loop equations based on dual quaternions and the natural exponential function substitution using tools from algebraic geometry. The analysis shows that the multi-mode single-loop 7R spatial mechanism has three motion modes, including a 2-DOF planar 5R mode and two 1-DOF spatial 6R modes and can transit between each pair of motion modes through two transition configurations. The higher-order mobility analysis shows that the 7R mechanism has two-instantaneous DOF at a regular configuration of any motion mode and three instantaneous DOF in a transition configuration. The infinitesimal motions that are not tangential to finite motions are of second-order in transition configurations between 2-DOF motion mode 1 and 1-DOF motion modes 2 or 3 or first-order in transition configurations between 1-DOF motion modes 2 and 3.
Comparing Machine Learning Regression Techniques for Transmission-Related Storm Outages
Authors: Clark Caitlyn E. , DuPont Bryony
Published: November 2018

In this study, we characterize machine learning regression techniques for their ability to predict storm-related transmission outages based on local weather and transmission outage data. To test the machine learning regression techniques, we use data from the central Oregon Coast — which is particularly vulnerable to storm-related transmission outages — for a case study. We test multiple regression methods (linear and polynomial models with varying degrees) as well as support vector regression methods using linear, polynomial, and Radial-Basis-Function kernels. Results indicate relatively poor prediction capability by these methods, but this is attributed to the lack of outage data (characteristic of low-probability, high-risk events), and a cluster of data points representing momentary (<0 seconds) outages. More long-term outage data could lead to better characterization of the models, enabling others to quantify the frequency of storm-related transmission outages based on local weather data. Only by understanding the frequency of these occurrences can a cost-benefit analysis for potential transmission upgrades or generation sources be completed.
Metamorphic Mechanism and Reconfiguration of a Biomimetic Quadruped Robot
Authors: Tang Zhao , Dai Jian S.
Published: November 2018

This paper presents reconfiguration with mobility change of an 8-bar metamorphic single-loop mechanism consisting of 8 revolute joints. Higher order analyses are employed to determine the local mobility of two special bifurcated positions of this 8-bar linkage. All the sub-motion branches and their connections of these two singular positions are revealed. Then a biomimetic quadruped robot is built by adopting the reconfigurable 8-bar linkage as its trunk. Based on the configuration spaces of this metamorphic mechanism, two strategies are introduced to control the reconfiguration between different modes.
Polynomial Representation of the Gaussian Process
Authors: Kristensen Jesper , Asher Isaac , Wang Liping
Published: November 2018

Gaussian Process (GP) regression is a well-established probabilistic meta-modeling and data analysis tool. The posterior distribution of the GP parameters can be estimated using, e.g., Markov Chain Monte Carlo (MCMC). The ability to make predictions is a key aspect of using such surrogate models. To make a GP prediction, the MCMC chain as well as the training data are required. For some applications, GP predictions can require too much computational time and/or memory, especially for many training data points. This motivates the present work to represent the GP in an equivalent polynomial (or other global functional) form called a portable GP. The portable GP inherits many benefits of the GP including feature ranking via Sobol indices, robust fitting to non-linear and high-dimensional data, accurate uncertainty estimates, etc. The framework expands the GP in a high-dimensional model representation (HDMR). After fitting each HDMR basis function with a polynomial, they are all added together to form the portable GP. A ranking of which basis functions to use in the fitting process is automatically provided via Sobol indices. The uncertainty from the fitting process can be propagated to the final GP polynomial estimate. In applications where speed and accuracy are paramount, spline fits to the basis functions give very good results. Finally, portable BHM provides an alternative set of assumptions with regards to extrapolation behavior which may be more appropriate than the assumptions inherent in GPs.
Low-Order Aeroelastic Modeling of Flapping, Flexible Wings
Authors: Jankauski Mark A.
Published: November 2018

Flapping insect wings deform under aerodynamic and inertial-elastic loads. Existing aeroelastic wing models are computationally expensive, and consequently, the physics governing flexible wing deformation are not well understood. This paper develops a low-order, one-way coupled aeroelastic model of an arbitrary geometry wing undergoing three-dimensional rotation. The model is developed using the Lagrangian formulation and generalized aerodynamic loads are determined through a blade-element-momentum approach. The in-air and in-vacuum responses of a simulated Hawkmoth wing are compared for various conditions. During normal flight, simulation results show aerodynamic loading causes a 25% increase in maximum wingtip deflection versus a wing flapping in vacuum. This suggests aerodynamics plays a moderate role in structural deformation. Further parametric studies indicate (1) deviations in flap frequency excite torsional resonance and (2) the relative phase between pitch and roll rotations dramatically affects in-air wing response. Both the aeroelastic model and simulation results can guide optimal wing design for small-scale flapping wing micro air vehicles.
HEKM: A High-End Equipment Knowledge Management System for Supporting Knowledge-Driven Decision-Making in New Product Development
Authors: Zhang Chao , Zhou Guanghui , Bai Quandong , Lu Qi , Chang Fengtian
Published: November 2018

Pre-existing knowledge buried in high-end equipment manufacturing enterprises could be effectively reused to help decision-makers develop good judgements to make decisions about the problems in new product development, which in turn speeds up and improves the quality of product innovation. Nevertheless, a knowledge-based decision support system in high-end equipment domain is still not fully accomplished due to the complication of knowledge content, fragmentation of knowledge theme, heterogeneousness of knowledge format, and decentralization of knowledge storage. To address these issues, this paper develops a high-end equipment knowledge management system (HEKM) for supporting knowledge-driven decision-making in new product development. HEKM provides three steps for knowledge management and reuse. Firstly, knowledge resources are captured and structured through a standard knowledge description template. Then, OWL ontologies are employed to explicitly and unambiguously describe the concepts of the captured knowledge and also the relationships that hold between those concepts. Finally, the Personalized PageRank algorithm together with ontology reasoning approach is used to perform knowledge navigation, where decision-makers could acquire the most relevant knowledge for a given problem through knowledge query or customized active push. The feasibility and effectiveness of HEKM are demonstrated through three industrial application examples.
Tension-Induced Raman Spectrum Enhanced Phenomena of Graphene Membrane
Authors: Hu Kai-Ming , Peng Bo , Yan Han , Zhang Wen-Ming , Xue Zhong-Yin , Di Zeng-Feng , Sun Ya-Ting
Published: November 2018

In the Letter, we reported the tension-induced Raman spectrum enhanced phenomena of graphene membrane. The standard micro-fabrication processes are utilized to fabricate micro-scale holes on Silicon-On-Insulator (SOI) wafers, and suspended graphene membranes are transferred onto target substrates with shallow holes and flat substrates using the dry and wet transfer techniques, respectively. The corrugated graphene near the hole is stretched smoothly due to the built-in strain during the transfer processes, and the intensity ratio between the 2D and G bands I2D/IG>5, which demonstrates the high quality of graphene sheet is obtained under the stretching stress. The intensity ratio between the 2D and G bands would diminish greatly when the graphene membrane is broken. Therefore, the Raman spectrum intensities of graphene membranes can be tuned by the built-in strain. The study can be helpful for further understanding the formation mechanism of corrugated graphene, the suppressing method of the small ripple in graphene, and the way to improve the quality of graphene.
Short-Time Kurtogram for Bearing Fault Feature Extraction Under Time-Varying Speed Conditions
Authors: Huang Huan , Baddour Natalie , Liang Ming
Published: November 2018

The kurtogram is a spectral analysis tool used to detect non-stationarities in a signal. It can be effectively used to determine the optimal filter for bearing fault feature extraction from a blurred vibration signal, since the transients of the bearing fault-induced signal can be regarded as non-stationary. However, the effectiveness of the kurtogram is diminished when the signal is collected from a bearing operating under time-varying speed conditions. There is a need to improve the performance of the kurtogram under time-varying speed conditions. In this paper, a short-time kurtogram method is proposed for bearing fault feature extraction under time-varying speed conditions. The performance of the short-time kurtogram is examined with experimental data. The results demonstrate that the short-time kurtogram can effectively be used to extract bearing fault features under time-varying speed conditions.
Simulation and Experiment Research on Shuffle and Clunk in Gear Shifting Process
Authors: Wu Guangqiang , Sun Shuo
Published: November 2018

The dynamics model of gear shifting process considering the state of clutch and synchronizers and the process of engagement and disengagement is established to realize the continuous simulation of the entire shifting process. The pitching dynamics module is introduced based on the coupled mechanism of torsional, longitudinal and vertical vibration of the system. The simulation reproduces the dynamic responses and states of eight analyzed phases in the whole process. The model is verified from the comparison between simulation and experimental results of four working conditions. Based on the simulation analysis of time-domain and time-frequency domain, the characteristics of shuffle and clunk phenomena are investigated and compared between four working conditions. The key influencing factors of the jerk degree and shuffle intensity are obtained through theoretical analysis, and the verification is made through the simulation comparison of the assessing metrics. The real vehicle test is also carried out focused on shuffle phenomenon. The differences of characteristic frequencies and intensities of shuffle phenomenon in different gear shifting conditions are compared and analyzed.
Multi-Level Function Specification and Architecture Analysis Using ESL: A Lock Renovation Pilot Study
Authors: Wilschut T. , Etman L. F. P. , Rooda J. E. , Vogel J. A.
Published: November 2018

In this paper, we present a pilot study to show the first proof-of-principle of the recently developed Elephant Specification Language (ESL). The Prinses Marijke locks in the Netherlands are due for a major renovation. To effectively organize the renovation project, engineers need insight into the network of dependencies between components that are due for renewal and components that remain, to ensure that the replacement parts will fit and function properly in the existing structure. ESL is used to write a structured multi-level function specification for the Prinses Marijke locks. From this specification, multi-domain matrix (MDM) models of the system architecture are automatically derived at multiple levels of granularity. These models show dependencies between components, between functions, and combinations thereof. The MDM models are used to gain insight in the system architecture, to visualize which parts of the lock system are affected by the renovation, and to determine which dependencies have to be accounted for during the renovation process. This information is required to effectively organize the renovation project.
Roller Bearing Fault Feature Extraction Based on Compressive Sensing
Authors: Lin Huibin , Tang Jianmeng , Mechefske Chris
Published: November 2018

Compressive sensing (CS) theory allows measurement of sparse signals with a sampling rate far lower than the Nyquist sampling frequency. This could reduce the burden of local storage and remote transmitting. The periodic impacts generated in rolling element bearing local faults are obviously sparse in the time domain. According to this sparse feature, a rolling element bearing fault feature extraction method based on CS theory is proposed in the paper. Utilizing the shift invariant dictionary learning algorithm and the periodic presentation characteristic of local faults of roller bearings, a shift-invariant dictionary of which each atom contains only one impact pattern is constructed to represent the fault impact as sparsely as possible. The limited degree of sparsity is utilized to reconstruct the feature components based on compressive sampling matching pursuit (CoSaMP) method, realizing the diagnosis of the roller bearing impact fault. A simulation was used to analyze the effects of parameters such as sparsity, SNR and compressive rate on the proposed method and prove the effectiveness of the proposed method.
Examination of Tactor Configurations for the Design of Vibrotactile Feedback Systems for Use in Lower-Limb Prostheses
Authors: Shi Sam , Leineweber Matthew J. , Andrysek Jan
Published: November 2018

Vibrotactile feedback may be able to compensate for the loss of sensory input in lower-limb prosthesis users. Designing an effective vibrotactile feedback system would require that users could perceive and correctly respond to vibrotactile stimuli applied by the tactors. Our study explored three key tactor configuration variables (i.e. vibratory intensity, prosthetic pressure, spacing between adjacent tactors) through two experiments. The vibration propagation experiment investigated the effects of tactor configurations on vibratory amplitude at the prosthesis-limb interface. Results revealed a positive relationship between vibratory amplitude and intensity, and a negative relationship between vibratory amplitude and prosthetic pressure. The vibrotactile perception experiment investigated the effects of tactor configurations on user response accuracy, and found that greater spacing between tactors, and higher prosthetic pressure resulted in more accurate responses from the subjects. These findings inform the design of a vibrotactile feedback system for use in lower-limb prostheses: 1) the tactors may be best placed in areas of slightly elevated pressure at the prosthesis-limb interface; 2) a higher vibratory intensity level should improve performance for vibrotactile feedback systems; and 3) more spacing between adjacent tactors improves user response accuracy.
Paradoxical Chaos-Like Chattering in the Bouncing Ball System
Authors: Schindler Kilian , Leine Remco I.
Published: November 2018

This paper reports and investigates paradoxical simulation results of the bouncing ball system. Chaos-like motion of the bouncing ball system with intermittent chattering (Zeno behaviour) is observed in simulations if the relative acceleration of the table exceeds a critical value. However, one can show that this is theoretically impossible. A detailed analysis is given by looking at the backward and forward dynamics of grazing solutions. It is shown in detail that a self-similar structure appears if the relative acceleration of the table exceeds the critical value.
Blended Spaces: Collaborative Work and Computer Supported Learning and Tools
Authors: Wendrich Robert E.
Published: November 2018

Individualized and cooperative design combined with hybrid design tools, have the capacity to act as the missing link between humans, society, and technology (STS). The blended design environments (spaces) entail innovative interactive software solutions and design tools to create meaningful communication, experiences, personal involvement and social inclusion within various contexts and/or domains. In this paper we present preliminary data on two research experiments, user modeling and participant observation. The study is based on a comparison between a loosely (i.e. raw) and a formalized (i.e. hyper design) structured approach facilitated in blended spaces (BS) for design and engineering. Findings, results and feedback on interaction (IxD), usability (UA) and experiences (UX) are discussed along design environment parameters, strategy and contextualization.
Passive Variable Friction Damper for Increased Structural Resilience to Multi-Hazard Excitations
Authors: Downey Austin , Sadoughi MohammadKazem , Cao Liang , Laflamme Simon , Hu Chao
Published: November 2018

Structural control systems, including passive, semi-active and active damping systems, are used to increase structural resilience to multi-hazard excitations. While semi-active and active damping systems have been investigated for the mitigation of multi-hazard excitations, their requirement for real-time controllers and power availability limit their usefulness. This work proposes the use of a newly developed passive variable friction device for the mitigation of multi-hazard events. This passive variable friction device, when installed in a structure, is capable of mitigating different hazards from wind and ground motions. In wind events, the device ensures serviceability, while during earthquake events, the device reduces the building’s inter-story drift to maintain strength-based motion requirements. Results show that the passive variable friction device performs better than a traditional friction damper during a seismic event while not compromising any performance during wind events.
A New Contact Model of Rough Surface Based on Analytical Method
Authors: Sun Yunyun , Xiao Huifang , Xu Jinwu
Published: November 2018

In this paper, an analytical contact model is proposed to study the contact behavior between two rough surfaces. Elliptical function is employed to describe contact stiffness of a single asperity, and the contact area is characterized by polynomial function in elastoplastic deformation regime. Results show that the proposed model ensures the continuity and smoothness of contact variables across different deformation regimes for a single asperity. The accuracy of the contact model has been demonstrated by the good agreement between the proposed model and the existing statistical model. Influences of material properties on normal contact force and interfacial stiffness have been further studied using the established model.
Research on Motion Error of Cylindrical Roller Bearings Under Radial Load
Authors: Yongjian Yu , Jishun Li , Guoding Chen , Yujun Xue , Zhuoyi Si , Gurgenci Halim
Published: November 2018

Since the rotary motion of a rolling bearing is implemented by bearing components under geometric constraints, the motion accuracy of an assembled bearing should also be the result of interaction among geometric errors of bearing components. Therefore, it is significant to understand the relationship between the geometric errors of bearing components and motion accuracy of an assembled bearing for the design of high accuracy bearing. Based on quasi-static analytical method, a mathematical model for motion error of cylindrical roller bearings is established considering the roundness error of outer raceway. The motion error of a rolling bearing is affected by the amplitude and harmonic order of the roundness error of outer raceway, number of rollers and the operating conditions such as radial load, rotary speed of outer ring. The effects of above parameters are analyzed. The results show that the motion accuracy of a cylindrical roller bearing degrades with the increase of amplitude of the roundness error of outer raceway and the rotary speed of outer ring. The variation of the radial displacement of outer ring varies periodically with the increase of the harmonic order of the roundness error of outer raceway, and its period is equal to the roller number. With the increase of the roller number, the variation of radial displacement of the outer ring fluctuates. The larger the radial load is, the smaller the variation of radial displacement of outer ring is. The results would be helpful to reduce the production costs by controlling the distribution of machining tolerance of bearing components.
Deformation Analysis of a Compliant Underactuated Finger Grasping a Soft Object
Authors: Mouazé Nicolas , Birglen Lionel
Published: November 2018

In the literature, many models of compliant fingers grasping rigid objects have been extensively discussed. However, when the objects are themselves deformable, as in many practical cases, the effect of compliant underactuated fingers onto these soft objects is generally not addressed due to the complexity of the model required for accurate results. This paper aims at addressing this issue by proposing to simulate deformations using a simple mass-spring model. This model discretizes the object similarly to how a pseudo-rigid body technique usually approximates the compliant finger. Comparisons between simulations using the proposed model and finite element analyses demonstrate that for a significant range of deformations our approach offers an efficient and accurate approximation while less computationally intensive.
A Unit-Consistent Error Measure for Mixed Linear Complementarity Problems in Multibody Dynamics With Contact
Authors: Enzenhöfer Andreas , Peiret Albert , Teichmann Marek , Kövecses József
Published: November 2018

Modeling multibody systems subject to unilateral contacts and friction efficiently is challenging, and dynamic formulations based on the mixed linear complementarity problem (MLCP) are commonly used for this purpose. The accuracy of the MLCP solution method can be evaluated by determining the error introduced by it. In this paper, we find that commonly used MLCP error measures suffer from unit inconsistency leading to the error lacking any physical meaning. We propose a unit-consistent error measure which computes energy error components for each constraint dependent on the inverse effective mass and compliance. It is shown by means of a simple example that the unit consistency issue does not occur using this proposed error measure. Simulation results confirm that the error decreases with convergence toward the solution. If a pivoting algorithm does not find a solution of the MLCP due to an iteration limit, e.g. in real-time simulations, choosing the result with the least error can reduce the risk of simulation instabilities.
Unified Rotational and Translational Stiffness Characterization of Compliant Shell Mechanisms
Authors: Leemans Joost R. , Kim Charles J. , van de Sande Werner W. P. J. , Herder Just L.
Published: November 2018

Compliant shell mechanisms utilize spatially curved thin-walled structures to transfer or transmit force, motion or energy through elastic deformation. To design with spatial mechanisms designers need comprehensive characterization methods, while existing methods fall short of meaningful comparisons between rotational and translational degrees of freedom. This paper presents two approaches, both of which are based on the principle of virtual loads and potential energy, utilizing properties of screw theory, Plücker coordinates and an eigen-decomposition, leading to two unification lengths that can be used to compare and visualize all six degrees of freedom directions and magnitudes of compliant mechanisms in a non-arbitrary physically meaningful manner.
A Positively-Engaged Infinitely Variable Transmission Using Split Helical Gears
Authors: Brush Ethan R. , Nelson Carl A.
Published: November 2018

Continuously variable transmissions (CVTs), and the subset known as infinitely variable transmissions (IVTs) with gear ratio ranges reaching zero (0:1 or 1:∞ or “geared neutral”), offer motors the ability to run in preferred angular velocity ranges independent of transmission output speed, allowing optimization for power, torque, and efficiency. This paper presents and analyzes a positively engaged IVT (PE-IVT) mechanism of an entirely new type and working principle which solves the problems of current CVTs and is applicable to the unique requirements of robots, electric vehicles (EVs), and hybridelectric vehicles (HEVs).
Reliability Analysis Using Second-Order Saddlepoint Approximation and Mixture Distributions
Authors: Papadimitriou Dimitrios I. , Mourelatos Zissimos P. , Hu Zhen
Published: November 2018

This paper proposes a new second-order Saddlepoint Approximation (SOSA) method for reliability analysis of nonlinear systems with correlated non-Gaussian and multimodal random variables. The proposed method overcomes the limitation of current available SOSA methods which are applicable to problems with only Gaussian random variables, by employing a Gaussian Mixture Model (GMM). The latter is first constructed using the Expectation Maximization (EM) method to approximate the joint probability density function of the input variables. Expressions of the statistical moments of the response variables are then derived using a second-order Taylor expansion of the limit-state function and the GMM. The standard SOSA method is finally integrated with the GMM to effectively analyze the reliability of systems with correlated non-Gaussian random variables. The accuracy of the proposed method is compared with existing methods including a SOSA based on Nataf transformation. Numerical examples demonstrate the effectiveness of the proposed approach.
Design of Mechanical Metamaterials via Constrained Bayesian Optimization
Authors: Sharpe Conner , Seepersad Carolyn Conner , Watts Seth , Tortorelli Dan
Published: November 2018

Advances in additive manufacturing processes have made it possible to build mechanical metamaterials with bulk properties that exceed those of naturally occurring materials. One class of these metamaterials is structural lattices that can achieve high stiffness to weight ratios. Recent work on geometric projection approaches has introduced the possibility of optimizing these architected lattice designs in a drastically reduced parameter space. The reduced number of design variables enables application of a new class of methods for exploring the design space. This work investigates the use of Bayesian optimization, a technique for global optimization of expensive non-convex objective functions through surrogate modeling. We utilize formulations for implementing probabilistic constraints in Bayesian optimization to aid convergence in this highly constrained engineering problem, and demonstrate results with a variety of stiff lightweight lattice designs.
Kinematic Analysis and Dimensional Synthesis of a New 2R1T Parallel Kinematic Machine
Authors: Xu Lingmin , Zhu Xubiao , Ye Wei , Li Qinchuan , Chen Qiaohong
Published: November 2018

This paper deals with the kinematic analysis and dimensional synthesis of a new 2R1T (R: rotation, T: translation) parallel kinematic machine (PKM). This is a 2PRU-UPR (P, R, U standing for prismatic, revolute and universal joint, respectively) PKM that is actuated by three actuated prismatic joints, two of which are mounted on the fixed base to reduce the movable mass. Firstly, the mobility and inverse kinematics of the 2PRU-UPR PKM are proposed. And then the motion/force transmissibility is evaluated by the local transmission index and good transmission workspace. Moreover, the singular configurations are obtained according to the motion/force transmissibility. Dimensional synthesis is carried out based on the GTW, and the optimized architectural parameters with good GTW are obtained. Finally, a prototype based on the optimized parameters has been developed, which has great potential in machining workpieces with curved surfaces.
Vehicle Stability Control on Tire Burst Steering and Braking Condition With Active Steering System
Authors: Dai Yaqi , Song Jian , Yu Liangyao
Published: November 2018

By analyzing the key safety problems under the front-outside-tire burst steering condition, a vehicle stability control strategy is proposed in this paper, which is based on active front steering and differential braking systems. Taken both the handling stability and safety into account, we divided the whole control strategy into two layers, which are yaw moment control layer and the additional steering angle & tire force distribution layer. To solve the similar linear problem concisely, the LQR control is adopted in the yaw moment control layer. To achieve the goal of providing enough additional lateral force and yaw moment while keeping the burst tire in appropriate condition, the additional steering angle provided by active front steering system and the tire force distribution was adjusted step by step. To test the proposed control strategy performance, we modelling a basic front-outside-tire burst steering condition, in which the tire blows out once the vertical pressure reach the predefined critical value. Through simulation on different adhesion coefficient road, the control strategy proposed in this paper performance quite better compare with the uncontrolled one in aspect of movement, burst tire protection, handling stability.
Automated Disassembly of Electronic Components: Feasibility and Technical Implementation
Authors: Palmieri Giacomo , Marconi Marco , Corinaldi David , Germani Michele , Callegari Massimo
Published: November 2018

The paper deals with the feasibility of a flexible robotic cell for the disassembly of electronic components. First, the need for an automated process for the end of life management of electronic boards is motivated: the reuse of electronic components represents a potential cost saving opportunity for a class of electronic board producers, other than an effective means to improve the waste management efficiency and the sustainability of the electronics sector. Then, starting from a state of the art survey, a technical implementation of the cell is proposed. Finally, some preliminary tests of the disassembly equipment, aimed at setting the most relevant process parameters, are described.
Spatial Concept Synthesis of Compliant Mechanisms Utilizing Non-Linear Eigentwist Characterization
Authors: Nijssen Joep P. A. , Radaelli Giuseppe , Herder Just L. , Ring J. B. , Kim Charles J.
Published: November 2018

Spatial compliant mechanism are challenging to design owing to their complex spatial kinetic and kinematic behavior. There are many synthesis methods to design compliant mechanisms, but they are often presented for planar mechanisms or have other limitations such as lack of designer input possibilities. In this paper a method based on the compliance ellipsoid is presented to create compliant mechanism topologies for spatial design cases. The result of this synthesis method is a qualitative concept which fundamentally creates the desired kinetic and kinematic profile. This concept can then be further refined using a large deformation eigentwist analysis, presented here. Lastly, these tools are used in a design example to show its potential.
Tuning of a Piezoelectric Harvester by Means of a Cantilever Spring-Mass System
Authors: Doria Alberto , Medè Cristian , Fanti Giulio , Desideri Daniele , Maschio Alvise , Moro Federico
Published: November 2018

The possibility of improving the performance of a piezoelectric harvester by means of a cantilever dynamic vibration absorber (CDVA) is investigated. The CDVA cancels the original mode of vibration of the harvester and generates two new modes. Some prototypes are developed using a mathematical model for predicting the natural frequencies of the coupled system. Impulsive tests were performed on prototypes. Experimental results show that a small CDVA can lower the main resonance frequency of an harvester of the same extent as a larger tip mass. The measured voltage shows also an high frequency resonance peak, which can be exploited for collecting energy. A multi-physics numerical model is developed for performing modal analysis and stress analysis. Numerical results show that the stress inside the piezoelectric material of the harvester with CDVA results smaller than the stress inside the harvester with a tip mass tuned to the same frequency.
Applying Design Roadmapping in New Product Development Education: Insights From Student Design Teams
Authors: Kim Euiyoung , Beckman Sara L. , Agogino Alice M.
Published: November 2018

A design roadmap is a canvas that facilitates embedding user experience design goals into the earliest stages of the design process by envisioning how a concept can evolve over time to meet changing user needs. This paper explores the development of design roadmap canvases by product design teams in an educational setting. It does so by (1) examining the design roadmapping workshop deliverables from new product development student teams at the University of California, Berkeley between 2014–2017 and (2) analyzing 107 survey responses from students in those workshops about their design roadmapping experiences. The paper describes the benefits to students using design roadmapping and insights into how best to engage students in design roadmapping exercises. Finally, based on the challenges students had with the process employed in the experiment, recommendations are provided to help educators and practitioners make productive use of design roadmaps.