bluuebunny/crossref_metadata_2025 huggingface dataset:
A System Reliability Method With Dependent Kriging Predictions
Authors: Zhu Zhifu , Du Xiaoping
Published: December 2016

When limit-state functions are highly nonlinear, traditional reliability methods, such as the first order and second order reliability methods, are not accurate. Monte Carlo simulation (MCS), on the other hand, is accurate if a sufficient sample size is used, but is computationally intensive. This research proposes a new system reliability method that combines MCS and the Kriging method with improved accuracy and efficiency. Cheaper surrogate models are created for limit-state functions with the minimal variance in the estimate of the system reliability, thereby producing high accuracy for the system reliability prediction. Instead of employing global optimization, this method uses MCS samples from which training points for the surrogate models are selected. By considering the dependence between responses from a surrogate model, this method captures the true contribution of each MCS sample to the uncertainty in the estimate of the system reliability and therefore chooses training points efficiently. Good accuracy and efficiency are demonstrated by three examples.
Optimal Design of a Metamorphic Parallel Mechanism With Reconfigurable 1T2R and 3R Motion Based on Unified Motion/Force Transmissibility
Authors: Gan Dongming , Dai Jian S. , Dias Jorge , Seneviratne Lakmal D.
Published: December 2016

This paper presents a metamorphic parallel mechanism which can switch its motion between one translation and two rotation (1T2R) motion and pure rotation (3R) motion. This feature stems from a reconfigurable revolute (rR) joint of which the rotation axis can be altered freely. Screw based geometric constraint is used to demonstrate the reconfiguration and mobility. Unified inverse kinematics, Jacobian matrix and motion/force transmissibility are provided using screws. Based on those, singularity loci are illustrated and optimal design of some key parameters are conducted considering both the 1T2R and 3R phases. Trade-off can be made between the maximum singularity-free workspace and transmission performance based on the optimal design results in this paper for specific applications requiring 1T2R and 3R motion.
Impacting a Clamped-Free Beam to Experimentally and Numerically Determine Higher Resonant Frequencies of Vibration
Authors: Shields Elvin B.
Published: December 2016

Clamped-free (cantilever) beams have practical applications. For example, it is not possible to use normal means to determine the modulus of elasticity for thin films. However, the film material can be deposited onto the beam substrate by sputtering or by applying the additive manufacturing technique and thereby change the beam’s stiffness as suggested by Dias da Silva et al [1]. The stiffness change causes a shift in the natural frequencies of the vibration of the beam and this shift can be used to determine the material properties of the film.

This study provides four methods of analysis: 1) formula calculation, which is used as the benchmark, 2) finite element method, 3) experimental method with accelerometer, and 4) experimental method with condenser microphone. Theoretical results are used as benchmarks and compared with the finite element method (FEM) and two experimental methods (accelerometer and condenser microphone). The challenge is to obtain results with the necessary accuracy (significant digits) at higher resonant frequencies of vibration. The two experimental methods were evaluated and the experimental method with condenser microphone showed the most promise for future work. Very little was found in the literature regarding the use of a condenser microphone to measure resonant frequencies.
Crushing Analysis of Tapered Ellipse Tubes Under Oblique Impact Loading
Authors: Gao Qiang , Wang Liangmo , Wang Yuanlong , Guo Fuxiang , Zhang Zunzhi
Published: December 2016

In this paper, a class of axisymmetric thin-walled tubes with two types of geometries (straight and tapered) and four kinds of cross-sections (square, rectangle, circle, ellipse) are considered as energy absorbing components under oblique impact loading. The crash behavior of these tubes are first investigated by nonlinear finite element analysis through LS-DYNA. It is found that the tapered tubes has the better crashworthiness performance than the straight ones under oblique impact regarding both specific energy absorption (SEA) and peak crushing force (PCF). Among the tapered tubes, the tapered ellipse tube (TET) has the best crashworthiness performance. Then by calculating the overall SEA considering load angle uncertainty effect, it is found that the weighting factors for different load angles are critical for evaluating the crashworthiness performance of the tubes.
The Design and Prototyping of Complex Compliant Mechanisms via Multi-Material Additive Manufacturing Techniques
Authors: Mirth John A.
Published: December 2016

The construction of compliant mechanisms is commonly performed in a single plane, due to the limitations on available manufacturing processes. This paper looks at the design and manufacturing of compliant mechanisms with members that cross over one another and thus need to be manufactured by alternative methods. The approach described here relies on the use of sheet-metal modeling software to create a 3D representation of a compliant linkage that can then be unfolded and 3D printed as a flat part. The modeling process begins with the development of a pseudo-rigid-body linkage to obtain a mechanism geometry to produce a specified motion. The PRBL is then converted to a lumped compliant mechanism by first laying out the locations of the flexural pivots in a modeling sketch, and then using the sheet metal feature of a solid-modeling program to create a model of the mechanism geometry. The sheet metal modeling process requires the user to separate the geometry into appropriate layers to provide clearance between links that cross over one another. The separation into proper layers includes the specification of a proper layer for each link, and the definition of the flexural pivots as belonging to either a single layer or to multiple layers. The sheet metal modeling must also pay attention to the need for the model to be able to unfold into a flat pattern. Once the sheet metal model is fully defined, the model is unfolded at the bends to obtain a flat pattern. The rigid portions of the mechanism are reinforced in the CAD model by thickening the regions of the model that lie between the sheet metal bends. The model is printed in its flat state, and then manually folded to its designed shape. This paper focuses on the design of relatively small models with the printing process being accomplished with the use of a desktop, dual material FFF 3D printer with soft PLA for the flexible material and ABS for the rigid reinforcement. The specific mechanism modeled in this paper is based on a Watt I six-bar linkage designed to imitate the motion of a finger. The size, space, and motion requirements of this design make the model an ideal candidate for conversion to a compliant linkage using the methods described in the paper. While the production process is simplified by the ability to use a 3D printer to produce the model, the design technique may also be applied to larger models where the parts are cut from flat stock using a variety of other manufacturing options.
A Cost-Effective Computerized Data Acquisition and Motor Current Signature Analysis Demonstrator for Industry and Academia
Authors: Georgescu Adrian , Simionescu P. A.
Published: December 2016

This paper presents the development, results and trainee perception of a laboratory experiment used for diagnosing the occurrence of different faults in impeller-pump induction motors by means of the Motor Current Signature Analysis (MCSA) technique. This is a quintessential experiment, relatively inexpensive and easy to implement, that combines elements of computerized data acquisition, Discrete Fourier Transform analysis and fault identification of electric motors. Following this laboratory exercise, students and trainees are able to understand and apply MCSA to determine common faults of induction motors. The test stand, experimental setup, and test procedure are described with sufficient details in the paper for others to build one of their own.
MeKin2D: Suite for Planar Mechanism Kinematics
Authors: Simionescu P. A.
Published: December 2016

MeKin2D is a collection of subroutines for kinematic simulation of planar linkages using a modular approach, for synthesis and analysis of disk-cam mechanisms with various types of followers, and for involute gear generation. The original set of subroutines accompanies as supplementary materials a book by this same author released in 2014. These, as well as other subroutines added since the book has been released are presented in the paper, together with examples accompanied by animations.
Identification of the Critical Stiffnesses of Motorcycles in Static and Dynamic Conditions
Authors: Doria Alberto , Taraborrelli Luca
Published: December 2016

Stiffness of structural elements has a significant effect on the dynamics of single-track vehicles, because it influences the stability of the typical modes of this class of vehicles (weave and wobble). Up to date no specific method for measuring the critical stiffnesses of front fork, chassis and swingarm is universally recognized. This measurement is difficult chiefly for two reasons. When a structural element of a single-track vehicle is loaded at one end it undergoes both bending and torsion deformation and stiffness has to be decomposed into the bending and torsion components. The stiffness characteristics measured in static conditions may be rather different from the ones measured in the presence of dynamic loads, owing to the excitation of vibration modes. The concept of Mozzi or twist axis is used in this paper for giving a lumped element representation of stiffness of structural elements of single-track vehicles. Then the differences between stiffness characteristics measured in static and dynamic conditions are highlighted and analyzed. Finally, a novel method is proposed for the decomposition of stiffness, it makes use of the axes of the bending and torsion modes. These axes are identified by means of impulsive tests measuring the frequency response functions of three points of a rigid plate that moves with the loaded end of the structural element. Experimental results dealing with swingarm, chassis and front fork are presented.
Quantitative Motor Assessment, Detection, and Suppression of Parkinson’s Disease Hand Tremor: A Literature Review
Authors: Ly Khoi , Cloutier Aimee , Yang James
Published: December 2016

Parkinson’s disease (PD) is difficult to detect before the onset of symptoms; further, PD symptoms share characteristics with symptoms of other diseases, making diagnosis of PD a challenging task. Without proper diagnosis and treatment, PD symptoms including tremor, bradykinesia, and cognitive problems deteriorate quickly into patients’ late life. Among them, the most distinguishable manifestations of PD are rest and postural tremor. Tremor is defined as an involuntary shaking or quivering movement of the hands or feet. Unified Parkinson’s Disease Rating Scale (UPDRS), Hoehn and Yahr (H&Y) scales are the most common rating scales that quantify the severity of PD. Due to the lack of consistency in these diagnostic tests, researchers are looking for devices for quantification and detection that can provide more objective PD motor assessments. Additionally, since there is currently no cure for PD, temporary PD symptom suppression is an active research area for improving patients’ quality of life. In this survey, the current state of research on Parkinson’s disease hand tremor quantification, detection, and suppression is discussed, especially focusing on electromechanical devices. The future direction of research on these devices is also considered.
Identification of Relationships Between Electroencephalography (EEG) Bands and Design Activities
Authors: Liu Lixin , Nguyen Thanh An , Zeng Yong , Hamza Abdessamad Ben
Published: December 2016

Electroencephalography (EEG) study of design activities has been drawing increasing attentions in design cognition research. The aim of this present paper is to identify EEG bands that are associated with design activities through principal component analysis (PCA). Based on the analysis of the data on 32 subjects collected from experiments conducted in the Design Lab at Concordia University, it was found that resting, problem solving and evaluation activities have relations to specific EEG bands. EEG powers of beta-2 (20–30Hz), gamma-1 (20–30Hz), and gamma-2 (30–40Hz) are mostly associated to the design activities whereas resting is mostly associated to alpha band (8–14Hz). In addition, there are differences in frequency above 20Hz between the resting before and after design activities. The work presented in this paper can be used to further quantify designer’s cognitive activities, which will ultimately improve the development of effective design tools and methods.
Muscle Force Prediction of 2D Gait Using Predictive Dynamics Optimization
Authors: Xiang Yujiang
Published: December 2016

Cyclic human gait is simulated in this work by using a 2D musculoskeletal model with 12 degrees of freedom (DOF). Eight muscle groups are modeled on each leg. Predictive dynamics approach is used to predict the walking motion. In this process, the model predicts joints dynamics and muscle forces simultaneously using optimization schemes and task-based physical constraints. The results indicated that the model can realistically match human motion, ground reaction forces (GRF), and muscle force data during walking task. The proposed optimization algorithm is robust and the optimal solution is obtained in seconds. This can be used in human health domain such as leg prosthesis design.
Mobility and Kinematic Paths of Foldable Origami Structures
Authors: Cai Jianguo , Qian Zelun , Feng Jian , Jiang Chao , Xu Yixiang
Published: December 2016

As one new type of deployable structures, foldable plate structures based on origami are more and more widely used in aviation and building structures in recent years. The mobility and kinematic paths of foldable origami structures are studied in this paper. Different constraints including the rigid plate, pin joints and the boundary conditions of linkages were firstly used to generate the system constraint equations. Then the degree of freedom (DOF) of the foldable plate structures was calculated from the dimension of null space of the Jacobian matrix, which is the derivative of the constraint equations with respect to time. Furthermore, the redundant constraints were found by using this method and multiple kinematic paths existing in origami structures were studied by obtaining all solutions of constraint equations. Different solutions represent different kinematic configurations. The degree of freedom and kinematic paths of a Miura-ori and a rigid deployable antenna were also investigated in details.
Web-Based Application for Algorithm Based Product Development Process of Integral Bifurcated Sheet Metal Parts
Authors: Weber Martins Thiago , Steinmetz Christian , Albrecht Katharina , Anderl Reiner
Published: December 2016

Within the Collaborative Research Center 666 the algorithm based product development process has been established. It is based on state of the art product development methodologies and enhanced in order to optimize the product development process of integral bifurcated sheet metal parts. Algorithms based on mathematical optimization approaches as well as the initial product requirements and constraints information are applied to obtain an optimized design as CAD-Model. Regarding this methodology there are still some challenges to be solved, such as reduction of iterations steps to elaborate final product design as CAD-model, use of heterogeneous data as well as software and enhancement of information exchange.

Therefore, this paper introduces a concept for a web-based application to support the algorithmic product development methodology and CAD modeling in CRC 666. It enables the development and adaptation of integral bifurcated parts based on the initial optimization data provided by XML-files. Besides the description of use cases and use scenarios, the concept is implemented as a web-based application for validation purposes. Based on the validation, advantages and limitations of the presented approach are discussed.
A General Technique to Evaluate the Effects of Manufacturing Errors on Positioning Precision During Design
Authors: Simas Henrique , Di Gregorio Raffaele
Published: December 2016

Industrial robots designed to accomplish high precision tasks require an accurate evaluation of the effects of manufacturing and assembly (geometric) errors on positioning precision. In the literature, such evaluations are mainly tailored on particular architectures and the proposed techniques are difficult to extend. Here, a general discussion on how to take into account geometric errors’ effects is presented together with a method for selecting either which workspace region is less affected by geometric errors or which geometric constants must be carefully sized to reduce these effects. The proposed method can be applied to any architecture. A case study is presented to better explain the method.
Smart Reading Aid for Detecting Problems With Reading Fluency and Comprehension
Authors: Rusák Zoltán , van de Water Niels , de Smit Bram , Horváth Imre , Van Der Vegte Wilhelm Frederik
Published: December 2016

Brain signal and eye tracking technology have been intensively applied in cognitive science in order to study reading, listening and learning processes. Though promising results have been found in laboratory experiments, there are no smart reading aids that are capable to estimate difficulty during normal reading. This paper presents a new concept that aims to tackle this challenge. Based on a literature study and an experiment, we have identified several indicators for characterizing word processing difficulty by interpreting electroencelography (EEG) and electrooculography (EOG) signals. We have defined a computational model based on fuzzy set theory, which estimates the probability of word processing and comprehension difficulty during normal reading. The paper also presents a concept and functional prototype of a smart reading aid, which is used to demonstrate the feasibility of our solution. The results of our research proves that it is possible to implement a smart reading aid that is capable to detect reading difficulty in real time. We show that the most reliable indicators are related to eye movement (i.e. fixation and regression), while brain signals are less dependable sources for indicating word processing difficulty during continuous reading.
The Unique Engineering Properties of Assur Groups/Graphs, Assur Kinematic Chains, Baranov Trusses and Parallel Robots
Authors: Hahn Elad , Shai Offer
Published: December 2016

Modular topological structures, commonly known as Assur groups, have been an important subject of research in machine theory over the past several decades. In this paper, some unique engineering properties which appear in this type of structures and only in them are exposed. The concept of Assur groups is reformulated in terms of graphs and named Assur Graphs (AGs). The graph representation enables to present the inter-connectivity between all the elements of the AG, which is the fundamental characteristic from which all its unique properties derive. This inter-connectivity leads to unique properties in three main engineering aspects of structures: kinematics, statics and singularity positions. These properties can be exploited for better analysis and synthesis of structures such as mechanisms, robots and trusses.
Vision-Based Wayfinding Simulation of Digital Human Model in Three Dimensional as-is Environment Models and its Application to Accessibility Evaluation
Authors: Maruyama Tsubasa , Kanai Satoshi , Date Hiroaki
Published: December 2016

Elderly and disabled individuals must be able to access the indoor and outdoor environment in an easy and safe manner. Accessibility must be assessed not only in terms of physical friendliness for users, but also of cognitive friendliness such as the ease of wayfinding. To ensure the ease of wayfinding, signage information available at every key decision point is essential because it enables people to find their way in unfamiliar environment. The aim of the present study is to develop virtual accessibility evaluation system that evaluates the environment accessibility from the cognitive friendliness aspect, such as the ease of wayfinding, by combining realistic human behavior simulation using a digital human model (DHM) with as-is environment models. To realize this system, we develop a vision-based wayfinding simulation algorithm for the DHM in textured three-dimensional (3D) as-is environment models. The as-is environment models are constructed with the structure-from-motion (SfM) technique. During the wayfinding simulation, the visibility and legibility of each sign are evaluated on the basis of the visual perception of the DHM and its visibility catchment area (VCA). The DHM walking trajectory is dynamically generated depending on the perceived sign. When a disorientation place is detected where the DHM cannot find any sign indicating its destination, plans for rearranging the signs are proposed by the simulation user and then examined using a developed virtual eyesight simulator (VES). The VES enables the user to check the DHM eyesight virtually during the wayfinding simulation through a head-mounted display. To mimic visual impairments, visual impairment filters are introduced into the VES. In this paper, we demonstrate the process of detecting the disorientation place, and planning and evaluating the rearranged signage.
Design and Static Analysis of Elastic Force and Torque Limiting Devices for Safe Physical Human-Robot Interaction
Authors: Zhang Meiying , Laliberté Thierry , Gosselin Clément
Published: December 2016

This paper presents the static analysis of elastic force and torque limiters that aim at limiting the forces that a robotic manipulator can apply on its environment. First, the design of one-degree-of-freedom force and torque limiting mechanisms is presented. It is shown that a single elastic component (spring) can be used to provide a prescribed preload and stiffness in both directions of motion along a given axis. Then, the mechanisms are analyzed in order to determine the nonlinear relationships between the motion of the mechanism and the extension of the spring. These relationships can then be used in the design of the force and torque limiters. Finally, the force capabilities of the mechanisms are investigated and numerical results are provided for example designs.
Mobility Analysis of Interconnected Hybrid Flexure Systems Using Screw Algebra and Graph Theory
Authors: Sun Frederick , Hopkins Jonathan B.
Published: December 2016

This paper introduces a general method for determining the mobility analysis of flexure systems of any complexity, including those that can’t be broken into parallel and serial flexure subsystems. Such systems are called interconnected hybrid flexure systems because they possess limbs with intermediate bodies that are connected by flexure systems or elements. The method in this paper utilizes screw algebra and graph theory to enable designers to determine the freedom spaces (i.e., the geometric shapes that represent all the ways a body is permitted to move) for all the bodies joined together by compliant flexure elements within interconnected hybrid flexure systems. Although many flexure-based precision motion stages, compliant mechanisms, and microarchitectured materials possess topologies that are highly interconnected, the theory for performing a mobility analysis of such interconnected flexure systems using traditional screw theory does not currently exist. The theory introduced here lays the foundation for an automated tool that can rapidly generate the freedom spaces of every rigid body within a general flexure system without having to perform traditional computationally expensive finite element analysis. Case studies are provided in the paper to demonstrate the utility of the proposed theory.
Dynamic Characteristics Analysis of Cable-Rib Tension Deployable Antenna
Authors: Ruiwei Liu , Guo Hongwei , Qinghua Zhang , Liu Rongqiang , Dewei Tang
Published: December 2016

Balancing stiffness and weight is of substantial importance for antenna structure design. Conventional fold-rib antennas need sufficient weight to meet stiffness requirements. To address this issue, this paper proposes a new type of cable-rib tension deployable antenna that consists of six radial rib deployment mechanisms, numerous tensioned cables, and a mesh reflective surface. The primary innovation of this study is the application of numerous tensioned cables instead of metal materials to enhance the stiffness of the entire antenna while ensuring relatively less weight. Dynamic characteristics were analyzed to optimize the weight and stiffness of the antenna with the finite element model by subspace method. The first six orders of natural frequencies and corresponding vibration modes of the antenna structure are obtained. In addition, the effects of structural parameters on natural frequency are studied, and a method to improve the rigidity of the deployable antenna structure is proposed.
Uncertainty Quantification in Metamodel-Based Reliability Prediction
Authors: Nannapaneni Saideep , Hu Zhen , Mahadevan Sankaran
Published: December 2016

Optimization under uncertainty has been studied in two directions — (1) Reliability-based Design Optimization (RBDO), and (2) Robust Design Optimization (RDO). One of the crucial elements in an RBDO problem is reliability analysis. Reliability analysis is affected by different types of epistemic uncertainty, due to inadequate data and modeling errors, along with aleatory uncertainty in input random variables. When the original physics-based model is computationally expensive, a metamodel has often been used in reliability analysis, introducing additional uncertainty due to the metamodel. This work presents a framework to include statistical uncertainty and model uncertainty in metamodel-based reliability analysis. Inadequate data causes uncertainty regarding the statistics (distribution types and distribution parameters) of the input variables, and regarding the system model parameters. Model errors include model form errors, solution approximation errors, and metamodel uncertainty. Two types of metamodels have been considered in literature for reliability analysis: (1) metamodels that compute the system model output over the desired ranges of the input random variables; and (2) metamodels that concentrate only on modeling the limit state. This work focuses on the latter type, using Gaussian process (GP) metamodels for performing both component reliability (single limit state) and system reliability (multiple limit states) analyses. A systematic procedure for the inclusion of model discrepancy terms in the limit-state metamodel construction is developed using an auxiliary variable approach. An efficient single-loop sampling approach using the probability integral transform is used for sampling the input variables with statistical uncertainty. The variability in the GP model prediction (metamodel uncertainty) is also included in reliability analysis through correlated sampling of the model predictions at different inputs. Two mechanical systems — a cantilever beam with point-load at the free end and a two-bar supported panel with point load at its center, are used to demonstrate the proposed techniques.
Influence of the Trajectory Planning on the Accuracy of the Orthoglide 5-Axis
Authors: Jha R. , Chablat D. , Rouillier F. , Moroz G.
Published: December 2016

Usually, the accuracy of parallel manipulators depends on the architecture of the robot, the design parameters, the trajectory planning and the location of the path in the workspace. This paper reports the influence of static and dynamic parameters in computing the error in the pose associated with the trajectory planning made and analyzed with the Orthoglide 5-axis. An error model is proposed based on the joint parameters (velocity and acceleration) and experimental data coming from the Orthoglide 5-axis. Newton and Gröbner based elimination methods are used to project the joint error in the workspace to check the accuracy/error in the Cartesian space. For the analysis, five similar trajectories with different locations inside the workspace are defined using fifth order polynomial equation for the trajectory planning. It is shown that the accuracy of the robot depends on the location of the path as well as the starting and the ending posture of the manipulator due to the acceleration parameters.
Reverse Engineering of Mechanical Parts: A Brief Overview of Existing Approaches and Possible New Strategies
Authors: Buonamici Francesco , Carfagni Monica
Published: December 2016

Reverse Engineering (RE), also known as “CAD reconstruction”, aims at the reconstruction of 3D geometric models of objects/mechanical parts, starting from 3D measured data (points/mesh). In recent years, considerable developments in RE were achieved thanks to both academic and industrial research (e.g. RE software packages).

The aim of this work is to provide an overview of state of the art techniques and approaches presented in recent years (considering at the same time tools and methods provided by commercial CAD software and RE systems). In particular, this article focuses on the “constrained fitting” approach, which considers geometrical constraints between the generated surfaces, improving the reconstruction result.

On the basis of the overview, possible theoretical principles are drafted with the aim of suggest new strategies to make the CAD reconstruction process more effective in order to obtain more ready/usable CAD models.

Finally, a new RE framework is briefly outlined: the proposed approach hypothesizes a tool built within the environment of an existing CAD system and considers the fitting of a custom-built archetypal model, defined with all the a-priori known dimensions and constraints, to the scanned data.
A Strain Distribution Based Classification of Ortho-Planar Springs: An Outlook to Piezoelectric Applications
Authors: van Kempen R. B. , Herder J. L. , Tolou N.
Published: December 2016

Ortho-planar springs are characterized by their planar shape and the dominant out of plane motion. These springs have benefits for integration in piezoelectric energy harvesting transducers, because of their compactness and monolithic planar manufacturing. The operating behavior in the first low frequency bending mode can be optimized by obtaining an appropriate strain distribution. A holistic design approach is proposed that contains both the focus on strain distribution as on the low frequency dynamic operation challenge. Therefore a classification based on the strain distribution has been made, which is derived from the perspective of loading, clamping and geometry of single flexures of ortho-planar springs. A comparison based on the type of strain (bending/torsion ratio), strain inversion,off-axis stiffness and the natural frequency-normalized area factor (NFNA) has been performed. The double clamped folded configuration shows the most potential for future optimal low frequency transducer designs.
Control of a Wheeled Inverted Pendulum: A Nonlinear Time-Frequency Approach
Authors: Baumann Tanja , Suh Steve
Published: December 2016

The wheeled inverted pendulum shown in Fig. 1 is a typical nonlinear system that is both nonholonomic and complex in dynamics. In this paper a novel control concept is applied to stabilize a wheeled inverted pendulum. The suggested controller requires no mathematical simplification or linearization of the system. Online identification and feed-forward control are realized by an adapted filtered-x least mean square algorithm (FXLMS). Using discrete wavelet transform (DWT), control can be exerted in both the time and frequency domains simultaneously. The results show that the proposed controller is robust even when the system is perturbed. The system can also be partially stabilized at positions out of the upper equilibrium. In this case the time domain error is small though the system stays broadband in the frequency domain.
Reducing Greenhouse Gas Emissions for Sustainable Bio-Oil Production Using a Mixed Supply Chain
Authors: Mirkouei Amin , Haapala Karl R. , Sessions John , Murthy Ganti S.
Published: December 2016

Recent growing interest in reducing greenhouse gas (GHG) emissions requires the application of effective energy solutions, such as the utilization of renewable resources. Biomass represents a promising renewable resource for bioenergy, since it has the potential to reduce GHG emissions from various industry sectors. In spite of the potential benefits, biomass is limited due to logistical challenges of collection and transport to bio-refineries. This study proposes a forest biomass-to-bio-oil mixed supply chain network to reduce the GHG emissions compared to a conventional bioenergy supply chain. The mixed supply chain includes mixed-mode bio-refineries and mixed-pathway transportation. Life cycle assessment is conducted for a case study in the Pacific Northwest with the assistance of available life cycle inventory data for biomass-to-bio-oil supply chain. Impact assessment, on a global warming potential (GWP) basis, is conducted with the assistance of databases within SimaPro 8 software. Sensitivity analysis for the case investigated indicates that using the mixed supply chain can reduce GHG emissions by 2–5% compared to the traditional supply chain.
Expected-Improvement-Based Methods for Adaptive Sampling in Multi-Objective Optimization Problems
Authors: Kristensen Jesper , Ling You , Asher Isaac , Wang Liping
Published: December 2016

Adaptive sampling methods have been used to build accurate meta-models across large design spaces from which engineers can explore data trends, investigate optimal designs, study the sensitivity of objectives on the modeling design features, etc. For global design optimization applications, adaptive sampling methods need to be extended to sample more efficiently near the optimal domains of the design space (i.e., the Pareto front/frontier in multi-objective optimization). Expected Improvement (EI) methods have been shown to be efficient to solve design optimization problems using meta-models by incorporating prediction uncertainty.

In this paper, a set of state-of-the-art methods (hypervolume EI method and centroid EI method) are presented and implemented for selecting sampling points for multi-objective optimizations. The classical hypervolume EI method uses hyperrectangles to represent the Pareto front, which shows undesirable behavior at the tails of the Pareto front. This issue is addressed utilizing the concepts from physical programming to shape the Pareto front. The modified hypervolume EI method can be extended to increase local Pareto front accuracy in any area identified by an engineer, and this method can be applied to Pareto frontiers of any shape. A novel hypervolume EI method is also developed that does not rely on the assumption of hyperrectangles, but instead assumes the Pareto frontier can be represented by a convex hull. The method exploits fast methods for convex hull construction and numerical integration, and results in a Pareto front shape that is desired in many practical applications.

Various performance metrics are defined in order to quantitatively compare and discuss all methods applied to a particular 2D optimization problem from the literature. The modified hypervolume EI methods lead to dramatic resource savings while improving the predictive capabilities near the optimal objective values.
A Compatibility Study of Static Balancing in Reconfigurable Mechanisms
Authors: Robertson P. D. , Kuo C.-H. , Herder J. L.
Published: December 2016

Reconfigurable mechanisms are a group of mechanisms that can change their topology or mobility while in operation. This property can add flexibility of the use of the mechanisms in constrained environments. Some situations require these mechanisms to be statically balanced. One example is a statically balanced lower-limb rehabilitation device, allowing patients who suffer from lower-limb paralysis to exercise without the need for a therapist to guide them. This mechanism by Tseng et al. [1] is one of the very few examples of a statically balanced reconfigurable mechanism. From literature it is known that there is no general way to statically balance these mechanisms. This paper aims to create an overview of the methods that can be applied by making a classification of reconfigurable mechanisms based on the intrinsic properties, then reviewing each group of this overview to find a generalised static balancing method. Only two mechanism groups show high compatibility with static balancing. One of these groups could be balanced using a single spring. The other shows the property that if one operation mode is balanced, no additional springs are needed for the other mode. Applying these techniques could reduce the overall complexity of the mechanism.
Hip Replacement Simulator for Predicting Dislocation Risk
Authors: Vaughan Neil , Dubey Venketesh N.
Published: December 2016

This paper reports development of a novel haptic 3D computer-based hip replacement simulator. A haptic device provides a kinesthetic interface in a virtual environment to conduct hip surgery. Predictive software enables modelling the risk of hip dislocation which was missing from previous simulators. The developed neural network autonomously matches compatible implant components from a library of industry standard part codes and sizes. The parameter driven simulator enables patient-specific modeling of femur and acetabulum. Combining haptic feedback with 3D graphics, the simulator enables training and assessment of orthopedic surgeons. The simulator includes haptic feedback for the orthopedic tools including reamer, saws, hip stems, acetabular cup implants. The hip replacement simulator allows surgeons to practice placing the stem and cup, providing a haptic sense of touch to replicate the in-vivo procedure. The novel capability to assess risk of dislocation could reduce post-operative dislocation. Enhancing the skill and accuracy of trainee hip surgeons can reduce the number of revision surgeries required, extend the life of artificial hip implants and improve patient safety, reducing costs for the health service.
Forward and Inverse Position Kinematics for the RRSSR Parallel Robot With Hardware Validation
Authors: Williams Robert L. , Lucas Ryan , Zhu J. Jim
Published: December 2016

This paper presents forward and inverse position kinematics equations and analytical solutions for the 2-dof RRSSR Parallel Robot. Two ground-mounted perpendicular offset revolute (R) joints are actuated via servomotors, and the single-loop parallel robot consists of passive R-S-S (revolute-spherical-spherical) joints in between the active joints. A study of the multiple solutions in each case is presented, including means to select the appropriate solutions. This rigid-link parallel robot forms the hip joints of the Ohio University RoboCat walking quadruped. The methods of this paper are suitable to assist in design, simulation, control, and gait selection for the quadruped. RoboCat hardware has been built and used to help validate the examples and results of this paper.
Spatial 3-SUR 1-RU Platform Robot Inverse Orientation Kinematics
Authors: Williams Robert L. , Kljuno Elvedin , Zhu J. Jim
Published: December 2016

This paper describes the spatial three-dof 3-SUR 1-RU spherical Parallel Platform Robot. This type of robot has been previously proposed by other authors, but the present design, platform-mounted actuators, and application are unique. Further, the inverse kinematics problem is solved analytically. This robot is under development at Ohio University to serve as the active orienting device for aerodynamic testing of unmanned aerial vehicles (UAV) with up to 3 m wingspan. The UAV will be tested on a Windmobile which is a ground vehicle that is driven with the test article on an instrumented truss extended in the front in an undisturbed flow field. This system is an inexpensive substitute for a large-scale wind tunnel for measuring aerodynamic parameters of the UAV.

The three-degrees-of-freedom (dof) of the platform robot are actively controlled by three servomotors (R joints) mounted to the underside of the moving platform and there is a passive fourth middle leg with passive R-U joints for support. The inverse orientation kinematics (IOK) problem is formulated and solved analytically in this paper. Given the three desired Euler Angles, the three required actuator angles are found. Geometrically this analytical solution is equivalent to finding the intersection point of two circles on different planes, independently for each of the three platform robot legs. The analytical solution requires finding the roots of a quartic polynomial. There are at most two real solutions (elbow-up and elbow-down) which means that there are always at least two imaginary solutions to the IOK problem, which are discarded. Examples are presented to demonstrate the platform robot IOK solution algorithm for use in practical platform robot control.
A General Framework for Evaluating Supply Chain Resilience
Authors: Chen Xi , Jing Pengyuan , Xi Zhimin
Published: December 2016

As the frequency of supply chain disruptions rises, businesses are increasingly realizing the value of supply chain resilience. A number of efforts has been devoted to define supply chain resilience or to develop risk mitigation strategies in order to maximize supply chain resilience. However, very few scholarly work has attempted to address how supply chain resilience should be quantified. This paper is dedicated to fill this gap by proposing a general framework for evaluating supply chain resilience. The proposed framework captures risks involved in the supply, the demand, the firm itself, and the external environment. In addition to risks, the framework also relates resilience to the supply chain’s risk prognosis capabilities, recover agility and recover time tolerance. Two example applications are used to demonstrate how this framework can be utilized to assess the effectiveness of risk mitigation strategies in supply chain design.
Mathematical Model for Rotor Bearing System by Considering the Effect of Shaft Dynamics and Localized Bearing Defects
Authors: Upadhyay N. , Jules M. , Kankar P. K. , Nbendjo B. R. Nana
Published: December 2016

This work is focused on development of model for unbalanced rotor bearing system to predict system behaviour in dynamic environment. In this model, nonlinearity is introduced due to two factors, namely, clearance of bearing and localized bearing races defects. The contact between the races and balls is considered as Hertzian contact which results in nonlinear restoring force due to elastic deformation in contact zone. In the mathematical formulation, the shaft is considered as rotating Timoshenko beam, supported on two ball bearings. After modelling of shaft corresponding equations representing the system behaviour has been formulated. The governing equations of motion are solved by Sixth order Runge-Kutta method. Bifurcation plots have been plotted to understand the state of the system in healthy condition and due to localized defects on races of the bearings. The Frequency spectrum and phase trajectory diagrams are also plotted for better understanding of the system response.
Quantification of Upper-Body Synergies: A Case Comparison for Stroke and Non-Stroke Victims
Authors: Heidari Omid , Roylance John O. , Perez-Gracia Alba , Kendall Eydie
Published: December 2016

Motion synergies are principal components of the movement, obtained as combinations of joint degrees of freedom, that account for common postures of the human body. These synergies are usually obtained by capturing the motion of the human joints and reducing the dimensionality of the joint space with techniques such as principal component analysis. In this work, an experimental procedure to investigate the synergies of the upper body is developed and the results of the pilot study are shown.

The upper-limb kinematics includes the joint complexes of the hand, wrist, forearm, elbow, and shoulder. The different kinematic models in the literature have been reviewed, and a serial chain is considered from the upper arm. A three degree of freedom (3-DOF) linkage containing two revolute joints and one prismatic joint has been chosen to simulate the shoulder motion. A spherical joint represents the Glenohumeral (GH) joint; the elbow and ulna-radius rotations are represented by two revolute joints and the wrist is modeled with two revolute joints. The hand has a tree structure and branches into the individual phalanges, with a 2-dof MCP joint and single R joints for the rest of the phalangeal joints.

The data are collected using motion capture and the joint angles are calculated using a combination of dimensional synthesis and inverse kinematics. Principal component analysis can be used to extract the synergies for a set of previously-selected motions. The motions are performed by healthy subjects and subjects who have suffered stroke, in order to see the changes in the motion primitives. It is expected that this study will help quantify and classify some of the loss of motion due to stroke.
Scheduling of Electronic Waste Collection Events
Authors: Raihanian Mashhadi Ardeshir , Behdad Sara
Published: December 2016

Despite recent efforts to alleviate the electronic waste (e-waste) problem, the product recovery management programs have not reached their full potential. The incompetency of the current e-waste recovery system mostly originates from the collection phase, where the consumers often have the tendency to keep their used electronics in storage rather than returning them. This may be due to lack of awareness about e-waste collection sites or the inconvenience of current e-waste collection infrastructure. To facilitate the collection of unwanted products, ‘e-waste collection’ events have been introduced for convenient and on-time disposal of electronic devices. However, factors such as consumer awareness, the volume of available e-waste for recovery, the resulting economic, environmental and social outcomes of those events, convenience of the location, laws and restrictions on the disposal of certain electronics, and the cost of holding such events make the scheduling a complicated decision, particularly for the remanufacturing industry. The purpose of this study is to characterize the e-waste collection scheduling problem and help decision makers determine the best schedule and characteristics of the e-waste event. An optimization framework has been developed to maximize the amount of collected e-waste.
On Complex Periodic Motions in a Time-Delayed, Double-Well Duffing Oscillator With Strong Excitation
Authors: Luo Albert C. J. , Xing Siyuan
Published: December 2016

The time-delayed double-well Duffing oscillator is extensively applied in engineering and particle physics. Determination of periodic motions in such a system is significant. Thus, in this paper, period-1 motions in the time-delayed double-well Duffing oscillator are discussed through a semi-analytical method. The semi-analytical method is based on the implicit mappings constructed by discretization of the corresponding differential equation. Complex period-1 motions are predicted and the corresponding stability and bifurcation analysis are completed. From predictions, complex periodic motions are simulated numerically, and the harmonic amplitudes and phases are presented. Through this study, the complexity of periodic motions in the time-delayed Duffing oscillator can be better understood.