bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability and Robustness of a 3D Slip Model for Walking Using Lateral Leg Placement Control
Authors: Budday Dominik , Bauer Fabian , Seipel Justin
Published: September 2013

The SLIP model has shown a way to easily represent the center of mass dynamics of human walking and running. For 2D motions in the sagittal plane, the model shows self-stabilizing effects that can be very useful when designing a humanoid robot. However, this self-stability could not be found in three-dimensional running, but simple control strategies achieved stabilization of running in three dimensions. Yet, 3D walking with SLIP has not been analyzed to the same extent. In this paper we show that three-dimensional humanoid SLIP walking is also unstable, but can be stabilized using the same strategy that has been successful for running. It is shown that this approach leads to the desired periodic solutions. Furthermore, the influence of different parameters on stability and robustness is examined. Using a performance test to simulate the transition from an upright position to periodic walking we show that the stability is robust. With a comparison of common models for humanoid walking and running it is shown that the simple control mechanism is able to achieve stable solutions for all models, providing a very general approach to this problem. The derived results point out preferable parameters to increase robustness promising the possibility of successfully realizing a humanoid walking robot based on 3D SLIP.
A Study on the Role of Expertise in Design Fixation and its Mitigation
Authors: Viswanathan Vimal , Linsey Julie
Published: September 2013

Engineering idea generation plays a vital role in the development of novel products. Prior studies have shown that designers fixate to the features of example solutions and replicate these features in their ideas. This is a major hindrance in idea generation as it restricts the solution space where designers search for their ideas. This study hypothesizes that though expert designers fixate to example features, they still can outperform novices in terms of quantity of ideas as they have a larger set of knowledge acquired through their experience. To investigate this, the experimental by Linsey et al. is replicated for novice designers. Novices generate ideas for a design problem in three groups: one group working with a fixating example, a second group working with the same example along with alternate representations for the design problem and a control group only presented with the problem and no additional materials. The obtained results support the hypothesis. Both novice and expert designers are fixated to the example features, but the expert designers generated more nonredundant ideas. The alternate representations of the design problem help experts in mitigating their fixation, whereas in novices, these have no effect.
Multistable Shape-Shifting Surfaces
Authors: Montalbano Paul , Lusk Craig
Published: September 2013

This paper presents designs for Multistable Shape-Shifting Surfaces (MSSS) by introducing bistability into the Shape-Shifting Surface (SSS). SSSs are defined as surfaces that retain their effectiveness as a physical barrier while undergoing changes in shape. The addition of bistability to the SSS gives the surface multiple distinct positions in which it remains when shifted to, i.e. by designing bistability into a single SSS link, the SSS unit cell can change into multiple shapes, and stabilize within the resulting shape, while maintaining integrity against various forms of external assaults normal to its surface. Planar stable configurations of the unit cell include, expanded, compressed, sheared, half-compressed, and partially-compressed, resulting in the planar shapes of a large square, small square, rhombus, rectangle, and trapezoid respectively. Tiling methods were introduced which gave the ability to produce out-of-plane assemblies using planar MSSS unit cells. Applications for MSSSs include size-changing vehicle beds, expandable laptop screens, deformable walls, and volume-changing rigid-storage containers. Analysis of the MSSS was done using Pseudo-rigid-Body Models (PRBMs) and Finite Element Analysis (FEA) which ensured bistable characteristics before prototypes were fabricated.
Optimization-Based Prediction of Aiming and Kneeling Military Tasks Performed by a Soldier
Authors: Hariri Mahdiar , Arora Jasbir , Abdel-Malek Karim
Published: September 2013

The objective of this study is to predict the “Aiming While Standing” and “Aiming While Kneeling” motion tasks for a soldier (human) using a full-body, three dimensional digital human model. The digital human is modeled as a 55 degree of freedom branched mechanism. Six degrees of freedom specify the global position and orientation of the coordinate frame attached to the pelvis of the digital human and 49 degrees of freedom represent the revolute joints which model the human joints and determine the kinematics of the entire digital human. Motion is generated by a multi-objective optimization approach minimizing the mechanical energy and joint discomfort simultaneously. A sequential quadratic programming (SQP) algorithm in SNOPT is used to solve the nonlinear optimization problem. The optimization problem is subject to constraints which represent the limitations of the environment, the digital human model and the motion task. Design variables are the joint angle profiles. All the forces, inertial, gravitational as well as external, are known, except the ground reaction forces. The feasibility of the generation of that arbitrary motion by using the given ground contact areas is ensured by using the well known Zero Moment Point (ZMP) constraint. During the kneeling motion, different parts of the body come in contact and lose contact with the ground which is modeled using a general approach. The ground reaction force on each transient ground contact area is determined using the equations of motion. It is assumed that enough friction exists that allow the human to generate reaction forces as determined by the ZMP constraint. Using these ground reaction forces, the required torques at all joints are calculated by the recursive Lagrangian formulation. Using the given method, we can predict realistic motions for the “Aiming While Standing” and “Aiming While Kneeling” tasks. The optimization approach is able to very well predict the “Natural Point of Aim” which is a well known concept for soldiers. In other words, the approach is able to predict the most comfortable final orientation of the feet on the ground for engaging a specific target. We also predict cases where the orientation of the soldier’s feet are enforced. Many virtual experiments have been conducted by changing the target location in the 3D space, changing the anthropometry of the soldier, adding armor to different joints, changing the variable parameters of the rifle, adding backpack and using different weapons.
Competencies for Innovating in the 21st Century
Authors: Siddique Zahed , Panchal Jitesh , Schaefer Dirk , Haroon Sammy , Allen Janet K. , Mistree Farrokh
Published: September 2013

This is the first paper in a four-part series focused on a competency-based approach for personalized education in a group setting. In this paper, we focus on identifying the competencies and meta-competencies required for the 21st century engineers. These competencies are the ability to be able perform a specific task, action or function successfully. In the second paper, we provide an overview of an approach to developing competencies needed for the fast changing world and allowing the students to be in charge of their own learning. The approach fosters “learning how to learn” in a collaborative environment. We believe that two of the core competencies required for success in the dynamically changing workplace are the abilities to identify and manage dilemmas. In the third paper, we discuss our approach for helping students learn how to identify dilemmas in the context of an energy policy design problem. The fourth paper is focused on approaches to developing the competency to manage dilemmas associated with the realization of complex, sustainable, socio-techno-eco systems.

A deep understanding of innovation-related competencies will be required if we are to meet the needs of our graduates in preparing them for the challenges of the 21st century. In recent years development of competencies for innovation, especially in engineering, has received signification attention. The nature of innovation and its components needs to be identified and analyzed to determine proper ways to nurture and develop them in engineering students.

There are two levels of competencies in any professional field, field-specific task competencies, and generalized skill sets, or meta-competencies. The task-specific competencies are benchmarks for graduates in a given field. Their level of attainment defines how well graduates are prepared to meet job demands and excel in the future. The general (meta) competencies are skill sets that enable them to function more globally, such as to work with others, function in organizations and meet organizational demands, and transfer task-specific skills to new challenges they have not encountered before.
Nonlinear Control of Semi-Active MacPherson Suspension System
Authors: Anubi Olugbenga M. , Crane Carl D.
Published: September 2013

This paper presents the control design and analysis of a non-linear model of a MacPherson suspension system equipped with a magnetorheological (MR) damper. The model suspension considered incorporates the kinematics of the suspension linkages. An output feedback controller is developed using an ℒ2-gain analysis based on the concept of energy dissipation. The controller is effectively a smooth saturated PID. The performance of the closed-loop system is compared with a purely passive MacPherson suspension system and a semi-active damper, whose damping coefficient is tunned by a Skyhook-Acceleration Driven Damping (SH-ADD) method. Simulation results show that the developed controller outperforms the passive case at both the rattle space, tire hop frequencies and the SH-ADD at tire hop frequency while showing a close performance to the SH-ADD at the rattle space frequency. Time domain simulation results confirmed that the control strategy satisfies the dissipative constraint.
Vehicle Stability Control Through Predictive and Optimal Tire Saturation Management
Authors: Sill Justin , Ayalew Beshah
Published: September 2013

This paper presents a predictive vehicle stability control (VSC) strategy that distributes the drive/braking torques to each wheel of the vehicle based on the optimal exploitation of the available traction capability for each tire. To this end, tire saturation levels are defined as the deficiency of a tire to generate a force that linearly increases with the relevant slip quantities. These saturation levels are then used to set up an optimization objective for a torque distribution problem within a novel cascade control structure that exploits the natural time scale separation of the slower lateral handling dynamics of the vehicle from the relatively faster rotational dynamics of the wheel/tire.

The envisaged application of the proposed vehicle stability strategy is for vehicles with advanced and emerging pure electric, hybrid electric or hydraulic hybrid power trains featuring independent wheel drives. The developed predictive control strategy is evaluated for, a two-axle truck featuring such an independent drive system and subjected to a transient handling maneuver.
Application of Dynamic State Variable Models for Multiple-Generation Product Lines With Cannibalization Across Generations
Authors: Lin Chun-Yu , Okudan Gül
Published: September 2013

Developing multiple-generation of products has become a mainstream tactic in today’s markets. The most notable case is Apple Inc.’s huge success with its iPod, iPhone and iPad product lines. Multiple-generation product lines require carefully planned strategies. Under a multiple-generation product development strategy, companies introduce a line of products to the market instead of introducing a single product to better utilize technology assets and resources in an elongated time span. For such product development and launch scenarios, cannibalization can occur, however. That is, multiple product generations compete in the same market and partition the company’s market shares. In the paper, we propose a new framework to predict the sales and introduction timing for every product generation in a multiple-generation product line while considering cannibalization. We demonstrate a case study implementing the proposed framework on Apple Inc.’s iPhone product line. The results show that the forecast performance of the model matches the realized real data.
A Systematic Approach to Engineering Knowledge Organization and Modeling
Authors: Ameri Farhad , Urbanovsky Colin , McArthur Christian
Published: September 2013

Capturing engineering domain knowledge is a challenging problem due to several factors such as the complexity of the knowledge as well as the multiplicity of the representation techniques with varying underlying syntax and semantics. The existing approaches for knowledge capture and organization in engineering are typically ad hoc in nature, which inhibit efficient knowledge sharing and deployment. The objective of this paper is to introduce a systematic methodology for knowledge capture, organization, and modeling in the manufacturing domain. The proposed methodology focuses on the conceptualization phase and utilizes Simple Knowledge Organization System (SKOS) early in the process for creating a controlled vocabulary, or thesaurus, in the domain of interest. The resulting SKOS-based thesaurus is a lightweight ontology that helps identify the core concepts that will be translated into formal classes in an axiomatic ontology such as MSDL. The proposed methodology is discussed with the aid of examples from metal casting domain. Also, use of Semantic Web Rule Language (SWRL) for representation of constraint knowledge is discussed in this paper.
Kinematic Synthesis of Rotary Machines Generated by Regular Curve-Polygons
Authors: Figliolini Giorgio , Rea Pierluigi , Grande Salvatore
Published: September 2013

This paper deals with the kinematic synthesis of volumetric rotary machines, which are generated by the planetary motion of regular curve-polygons.

In particular, the synthesis of both outer and inner conjugate profiles has been formulated as envelope of the polycentric profiles of a generating regular curve-polygon with any number of lobes, different radii of the circumcircle and rounded corners.

A regular curve-polygon with cusp corners can be obtained as a particular case, like the Reuleaux triangle.

Finally, the proposed formulation has been implemented in a Matlab code and several examples are reported.
Computational Analysis to Design Energy Efficient Built Environments
Authors: Abou-Nassar Guy , Siddique Zahed , Fithian Lee
Published: September 2013

Double skin facades (DSF) provide a means of enhancing the energy saving capabilities of buildings. By being able to respond dynamically to changing ambient conditions using natural ventilation, shading devices, and/or thermal insulation devices or strategies, DSFs are being incorporated into modern architecture and even retrofitted in some older structures to reduce the energy required to balance the load input into the building. Utilizing a general building model and weather conditions and integrating various designs for DSFs, a comparative study can be made to support or oppose the different designs changes being made. The analysis of the set-up will be performed by Fluent, a computational fluid dynamics (CFD) software. Fluent will solve for the Navier-Stokes equations and turbulent flow using the finite volume method. These results show that the energy necessary to power the HVAC system decreases with certain configurations.
Variational Formulation for Frictional Interface Dynamics
Authors: Truster Timothy , Masud Arif , Bergman Lawrence A.
Published: September 2013

The dynamic response of component bolted joints often plays a significant role in the overall behavior of a structural system. Accurate finite element simulation of these problems requires proper treatment of the interface conditions. We present a formulation carefully suited to these problems that incorporates discontinuous Galerkin (DG) treatment locally at the interface. The present work is an extension of our previous investigations of friction models within a finite element method for quasi-static problems. The current emphasis is on the treatment of the inertial term and ensuring that artificial resonance is not induced by the discrete interface. The weak imposition of continuity constraints allows the stick-slip behavior at the jointed surface to proceed smoothly, reducing the numerical instability compared to node-to-node contact techniques. As a model problem, we simulate the dynamic response of a lap joint subjected to an impulse axial force assuming Coulomb friction at the interface.
Design of Cellular Self-Organizing Systems
Authors: Chiang Winston , Jin Yan
Published: September 2013

Technology development is facing increased challenges as engineers begin to tackle the problem domains with greater uncertainty. Future engineered systems must be able to function in unpredictable environments such as deep ocean, rough terrain, and outer space while performing uncertain tasks like hazardous waste cleanup and search-and-rescue missions. Furthermore, the increasing size of engineered systems introduces unplanned interdependencies of components. Complex systems can provide the adaptability in order to manage uncertainties that traditional systems cannot. As the uncertainty of the problem domain increases, engineering design methods must be advanced in order to properly address the changing needs and constraints. This paper proposes a new approach inspired by natural phenomena in order to extend the design envelope towards an artificial nature. This approach broadens the traditional design and re-design methods by utilizing the self-organization process exhibited in natural systems. From a design point of view, the critical question is: how can system adaptability be designed into complex systems based only on local interactions between (many) simple cells? The goal is to design systems that excel in hostile and unpredictable environments where it is impossible for the designer to conceptualize every possible contingency. The key is to focus on the interactions and behaviors of the system. In this paper, we suggest a meta-behavior model for cellular self-organization systems that can be used as a design approach to guide emergent function capacities.
Characterization of Fatigue Dynamics Under Deterministic and Stochastic Excitation
Authors: Nguyen Son Hai , Falco Mike , Liu Ming , Chelidze David
Published: September 2013

Estimating and tracking dynamics of crack growth is essential for fatigue failure prediction. A new experimental system coupling structural and crack growth dynamics was used to show fatigue damage accumulation is different under chaotic and stochastic loading, even when both excitations have similar spectral and statistical signatures. Furthermore, conventional rain-flow counting method considerably overestimates damage in case of chaotic forcing. Important nonlinear loading characteristics are identified to guide the new fatigue model development.
A Service Failure Modes Identifying Method to Realize Highly Reliable Services
Authors: Kurita Yusuke , Kimita Koji , Shimomura Yoshiki
Published: September 2013

Recently, service has been recognized as an effective means to enhance customer satisfaction. The importance of service is widely accepted. According to this background, the authors of this paper have carried out conceptual research on service design from the engineering viewpoint. The series of this research is called “Service Engineering.” In order to achieve a successful service, service providers should maintain the quality of their service and always satisfy their customers. Namely, the provision of highly reliable service is essential for service providers to survive in the target market. In order to realize highly reliable products or services, in general, it is an effective approach to prevent failures from occurring in use phase. In this study, we aim to support service failure analysis in order to minimize the occurrence of failures. This paper proposes a method for identifying the states of service failures. Specifically, we define service failure and propose a procedure to identify the states of service failures with models that are proposed in Service Engineering. The proposed method is verified through its application to a practical case.
USV Trajectory Planning for Time Varying Motion Goals in an Environment With Obstacles
Authors: Svec Petr , Thakur Atul , Shah Brual C. , Gupta Satyandra K.
Published: September 2013

Safe and efficient following of a time varying motion goal by an autonomous unmanned surface vehicle (USV) in a sea environment with obstacles is a challenge. The vehicle’s tracking capability is inherently influenced by its dynamics, the motion characteristics of the motion goal, as well as by the configuration of obstacles in the marine environment. We have developed an approach that utilizes a lattice-based trajectory planning to generate a dynamically feasible, resolution optimal, collision-free trajectory to allow the vehicle to reliably reach the motion goal. We utilized a trajectory following controller to achieve high tracking efficiency while still preserving motion safety. The entire approach is based on the developed USV system architecture that encapsulates the necessary trajectory planning components. We demonstrated the effectiveness of the developed planner in a simulated environment with static obstacles. In addition, we have developed a physical evaluation setup.
Workspace of a Flexure Hexapod Nanopositioner
Authors: Shi Hongliang , Su Hai-Jun
Published: September 2013

This paper studies the workspace of a flexure-based, hexa-pod nanopositioner previously built by the National Institute of Standards and Technology (NIST) which can produce high-resolution motions in six degree of freedom by actuating linear actuators on planar tri-stage. Because there is a lack of work in workspace of such kind of compliant mechanisms, the controller is typically limited to a very small range of motion in order to avoid material failure. In this work, we seek to derive a kinematic model for predicting the workspace of such kind of flexure based platforms by assuming that their workspace is mainly constrained by the deformation of flexure joints. We first study the maximum deformation including bending and torsion angles of each flexure joint. We then derive the inverse kinematics and calculation of bending and torsion angles of this compliant platform. To obtain the workspace of the mechanism, we developed a computational algorithm that varies the displacement of the top platform to extreme positions till the deformation of any flexure exceeding a maximum value. To demonstrate this approach, we provided example studies including constant orientation workspace and constant position workspace. We compare results with a finite element model of the entire platform. The error is 4.74% for original analytical model and 8.26% for simplified analytical model. This model is beneficial in guiding design engineers in maximizing workspace of flexure based parallel compliant mechanisms. To the end-users of the positioner, it gives them a guidance on how to efficiently exploit the workspace of the nanopositioner.
A Nonlinear System for Harvesting Energy From Sustained Low-Level Vibration
Authors: Remick Kevin , Triplett Angela , Quinn D. Dane , McFarland Donald M. , Vakakis Alexander , Bergman Lawrence
Published: September 2013

We address the conversion of mechanical energy from low-level ambient vibration into usable electrical energy. Development of this self-renewing energy source is vital to portable electronics and wireless sensors, especially since battery development has reached a plateau over the past decade. The passive nature of the proposed energy harvesting system provides for this self-renewing energy source. Conventional vibration energy harvesting systems are often based on linear elements, requiring specific tuning to achieve resonance and, thus, acceptable performance. This tuning is based on the predominant frequency of the ambient vibration. Linear energy harvesting systems are less desirable because ambient environmental conditions such as frequency content change with time, decreasing the performance of the system. This project focuses on the unique properties of a class of strongly nonlinear vibrating systems to effectively harvest energy under several excitation conditions. These excitations include low-level vibration from a wide range of environmental conditions including frequency content and low-level successive impulses at various frequencies. The later excitation condition is examined in this work. Numerical simulations of the proposed model, an essentially nonlinear oscillator with purely cubic stiffness attached to a larger grounded linear oscillator, have shown capture into sustained dynamic instability from successive low-level impulsive excitations. This sustained dynamic instability results in high energy harvesting efficiency. The electromechanical coupling is realized by a piezoelectric element in the mechanical system with voltage dissipated across a resistive load in the electrical system. This study focuses on characterizing the response of the system to varying parameters, such as fundamental period of the linear oscillator, impact frequency, and impact magnitude. An optimal fundamental period and impact frequency for dynamic instability are examined in this work. Analysis of the frequency-energy relation reveals the presence of sustained dynamic instability when the system operates under these specific parameters, leading to an optimized system for experimental validification.
The Synthesis of the Axodes of Spatial Four-Bar Linkages
Authors: Figliolini Giorgio , Rea Pierluigi , Angeles Jorge
Published: September 2013

The paper introduces a procedure for the motion analysis of a four-bar linkage by means of dual algebra and the Principle of Transference. This procedure allows the mapping of the motion from the Euclidean to the spherical dual space. In particular, the position analysis of a spatial four-bar linkage is formulated by referring to a spherical four-bar linkage, which moves on the dual unit sphere. Moreover, both fixed and moving axodes of the coupler link are obtained, as traced by the spatial motion of the instant screw axis (ISA) with respect to the fixed and moving frames. These ruled surfaces reproduce the spatial motion of the coupler link upon relatively rolling and sliding around and along the ISA. Finally, the proposed procedure has been implemented in MatLab, in order to analyze the motion of the different types of four-bar linkages, including the Bennett mechanism and the Hooke joint. The motion is illustrated by means of animations of the four-bar linkages and their axodes.
Dynamics-Based Model for a New Class of a Rectilinear-Gait for a Snake-Inspired Robot
Authors: Hopkins James K. , Gupta Satyandra K.
Published: September 2013

Snake-inspired locomotion is much more maneuverable compared to conventional locomotion concepts and it enables a robot to navigate through rough terrain. A rectilinear gait is quite flexible and has the following benefits: functionality on a wide variety of terrains, enables a highly stable robot platform, and provides pure undulatory motion without passive wheels. These benefits make rectilinear gaits especially suitable for search and rescue applications. However, previous robot designs utilizing rectilinear gaits were slow in speed. This paper introduces a new class of rectilinear gaits to be utilized by a snake-inspired robot design which is capable of pure linear motion and variable traction. The general model for the gait class is based on serial robot dynamics using the Lagrangian formulation. The gait class includes four unique gaits: a forward and a turning gait, which both emphasize speed for the robot; and a forward and turning gait which emphasize traction. Also, we perform an analysis of the variable traction concept.
Kinematic Synthesis of Fiber Reinforced Soft Actuators in Parallel Combinations
Authors: Bishop-Moser Joshua , Krishnan Girish , Kim Charles , Kota Sridhar
Published: September 2013

Complex controlled motions, flexible surfaces, and minimal moving mass all drive the need for soft robots using fiber reinforced elastomer enclosures (FREEs) in a parallel configuration. This paper addresses the challenge of synthesizing a design with desired kinematics, as only small portions of the entire design space have been previously investigated. A systematic characterization of the kinematic freedom, constraint, and actuation directions of all circumferentially and longitudinally repeating fiber topologies is determined. The parallel kinematics is mapped for the combinations of actuators by determining the sets of mobilities necessary in the constituent members for all possible output motions. The kinematics of all possible parallel combinations for pairs and triangular triplets of FREEs are mapped. A graphical user interface (GUI) is presented, which allows a user to input a kinematic specification and generate all feasible FREE sets and their respective kinematics. With the entire design space mapped and easily accessible, a range of possible applications across a span of kinematic requirements becomes readily attainable. A case study is performed to verify the ability of the GUI to determine feasible FREE sets for a pick-and-place manipulator task.
A Study on the Representation of Examples in Learning Engineering Concepts
Authors: Atilola Olufunmilola , Viswanathan Vimal , Linsey Julie
Published: September 2013

The use of examples in engineering curricula is a commonly used means to teach engineering students new concepts and ideas; these examples play an important role in teaching engineering students how to become technically competent engineers and designers. Being able to learn from examples and avoid fixation to those examples is an important task in that process. Design fixation is a major constraint in design thinking as it limits the solution space where designers search for their ideas. The experiments described in this paper aims to investigate how students fixate to different types of representations. A pilot study comparing sketched and physical representations of examples shows that students are less likely to fixate to the design specifications of examples provided in the form of physical model, this suggests that they are able to better understand the design limitations of examples presented in the form of a physical model. Based on the preliminary results from this pilot experiment, the framework for a follow-up experiment is developed. This second experiment will explore the trend observed in the pilot study further and will compare how students fixate on and derive information between sketched and computer-aided design representations.
A Fourier Descriptor Based Approach to Design Space Decomposition for Planar Motion Approximation
Authors: Li Xiangyun , Zhao Ping , Ge Q. J.
Published: September 2013

This paper deals with the classical problem of dimensional synthesis of planar four-bar linkages for motion generation. Using Fourier Descriptors, a given motion is represented by two finite harmonic series, one for translational component of the motion and the other for rotational component. It is shown that there is a simple linear relationship between harmonic content of the rotational motion and that of the translational motion for a planar four-bar linkage. Furthermore, it is shown that the rotational component can be used to identify the initial angle and the link ratios of a four-bar linkage. The rest of the design parameters of a four-bar linkage such as location of the fixed and moving pivots can be obtained from the translational component of the given motion. This leads naturally to a decomposed design space for four-bar motion synthesis for approximate motion generation.
Fault Detection in Gearbox With Non-Stationary Rotational Speed Using CWT Feature Extraction, PCA Reduction and ANN Classifier Methods
Authors: Heidari Hojat , Ohadi Abdolreza
Published: September 2013

Gearbox fault diagnosis is one of the core research areas in the field of condition monitoring of rotating machines. The aim of this paper is to present an intelligent method for fault diagnosis of a kind of automotive gearbox in run-up condition based on vibration signals. The vibration signals are obtained from an acceleration sensor and sampled at constant time increment by AdvantechTM PCI-1712 card. Automotive gearbox test setup has been designed and constructed in Acoustics Research Laboratory in Amirkabir University of Technology. To process the non-stationary vibration signals, the re-sampling technique at constant angle increment is combined with the continuous wavelet transform (CWT) and the wavelet coefficients of the signals are obtained. The statistical parameters of the wavelet coefficients are extracted, and then the principle component analysis (PCA) is introduced to enhance the pattern recognition and reduce the dimensionality of the original feature space. Gearbox is considered in healthy, chipped tooth and worn teeth gears conditions. Finally, a feedforward multilayer perceptron (MLP) neural network is used for classification. The experimental results show that the adoption of PCA diagnosis method leads to higher accuracy and less training time for fault detection of the gear chip and wear.
Active Aerodynamic System to Improve the Safety and Handling of Race Cars in Lane Change and Wet Road Maneuvers
Authors: Diba Fereydoon , Barari Ahmad , Esmailzadeh Ebrahim
Published: September 2013

Motor vehicle racing is usually supported by advanced engineering technologies considering every attempt to improve the performance of the car. A major objective of the engineering support is to enhance the handling and safety of race cars. The normal force on every tire has important effects on the handling properties, longitudinal dynamic and the safety of vehicle. Therefore, developing technologies to control and adjust these forces is highly desirable. The capability of active aerodynamic system to compensate the overall downward force of the vehicle has been widely published in literature. This paper shows the effectiveness of an actively controlled aerodynamic system to improve the handling and safety of a small-size race car in a lane-change maneuver and driving on wet roads. The analyses of a nonlinear vehicle model with active aerodynamic system, the controller structure and the control law have been presented. Computer simulations were carried out to verify the model and evaluate the performance of the control system.
Characteristic Lengths and Distances: Fast and Robust Features for Nonlinear Time Series
Authors: Nguyen Son Hai , Chelidze David
Published: September 2013

Estimation of most of the metrics used to characterize dynamical systems’ output require fairly long time series (e.g., Lyapunov Exponents, Fractal Dimensions), or substantial computational resources (e.g., phase space warping metrics, sensitivity vector fields). In many practical applications, when there is abundance of data (e.g., in Atomic Force Microscopy) fast and simple features are needed, and when there is sparsity of data (e.g., in many Structural Health Monitoring situations) robust features are needed. Here, we propose a new class of features based on Birkhoff Ergodic Theorem, which are fast to calculate and do not require large data or computational resources. Applications of these metrics, in conjunction with the smooth orthogonal decomposition, to identifying underlying processes causing nonstationarity both in simulations and actual experiments are demonstrated.
Reverse Logistics Network Design for the Collection of End-of-Life Vehicles
Authors: Dai Hang , Wang Qing
Published: September 2013

Reverse logistic network design problems involve strategic decisions which influence tactical and operational decisions. In particular, they involve facility location, transportation and inventory decisions, which affect the cost of the distribution system and the quality of the customer service level. Locating a collection centre is an important strategic decision, as purchasing or building facilities requires sizable investment; also the network transportation cost is affected by the selection of facility locations. The location that is selected must therefore take into account all the parameters and variables that are relevant and the decision may even affect demand.

In this paper, network design for reverse logistics is investigated to solve the End-of-life Vehicles (ELV) collection centres location problem. We start by giving an understanding of the process of this reverse logistics network design by considering the features of reverse logistics, the role of ELV management and use of optimization methods. Based on this, a reverse logistics network design case for collection of End-of-life Vehicles is presented by formulating the problem into a mixed-integer linear program (MILP), taking into consideration the Capacitated Facility Location Problem. The solution to this model is obtained using IBM CPLEX Optimization Studio©. In addition the applicability of the model in other reverse logistic networks is discussed and the subjects for further research are pointed out.
Meta-Material Design of the Shear Layer of a Non-Pneumatic Wheel Using Topology Optimization
Authors: Czech Christopher , Guarneri Paolo , Fadel Georges
Published: September 2013

The meta-material design of the shear layer of a non-pneumatic wheel was completed using topology optimization. In order to reduce the hysteretic rolling loss, an elastic material is used and the shear layer microstructure is defined to achieve high compliance comparable to that offered by the elastomeric materials. To simulate the meta-material properties of the shear layer, the volume averaging analysis, instead of more popular homogenization methods, is used as the relative size of the shear layer places realistic manufacturing constraints on the size of unit cells used to generate the meta-material. In this design scenario the properties predicted by the homogenization methods are not accurate since the homogenization scaling assumptions are violated. A number of optimal designs are shown to have meta-material properties similar to those of the linear elastic properties of elastomers, making them good meta-material candidates for the shear layer of the non-pneumatic wheel.
Efficient Simulation of Load Cases of Wind Turbines
Authors: Müller Andreas , Keil Albrecht , Freudenberg Heiko
Published: September 2013

Wind turbines have become the sustainable backbone of green energy. This is not least because of the development of complex models enabling numerical simulation of the turbine dynamics. Such simulation models, combining non-linear flexible and rigid substructures, wind field as well as converter and operational management, allow for detailed investigations of all parts of the turbine and its overall performance. However, such investigations require to long simulation times.

For a wind turbine design to get certified it must pass extensive simulation runs. The current standards require a few thousand different load case scenarios, which apparently poses a great challenge to the simulation tools. Even more, automatic mass simulation of predefined load cases requires capabilities that standard simulation tools are lacking, including parallel computation features indispensable for such applications.

In this paper a tailored software solution for distributed batch simulation of wind turbines is presented. The turbine model is described in detail and the implementation in the commercial multibody software alaska is outlined. Special emphasize is given to the structure of the software. The simulation tool is validated and successfully applied in the industrial design and certification.
On the Effects of Driving Amplitude, Frequency and Magnetic Fields on the Feed Rate of a Vibratory Micro-Pin Feeder
Authors: Rimai Benjamin E. , Cipra Raymond J.
Published: September 2013

The use of micro-pin feeder-bowls has been established as a way to singulate and orient micro-scale metallic pins of varying lengths. Increasing the rate and reliability with which pins can feed through the bowl is important when considering the use of such a feeder-bowl in an industrial setting.

Previous experimental work, which was limited to a single driving frequency and small range of driving amplitudes of the feeder-bowl, showed low feed rates and long capture times for pins whose aspect ratio exceeded five-to-one. New experimental work has shown that by altering the driving amplitude and frequency of the feeder-bowl, pins with aspect ratios exceeding seven-to-one could be fed.

Because the frequency response of feeder-bowls may be limited, other techniques for improving the feed rate for long pins were also sought. One such technique was the magnetizing of the pins to increase their response to a magnetic field which surrounded the feeder-bowl. In some circumstances, more than a 70% reduction in average capture time was observed.

The improved capture performance for long pins will permit more freedom in the design of devices that can be assembled with the aid of vibratory micro-pin feeder-bowls. The research results will also be used to improve the accuracy of feeder bowl simulations.
The Effectiveness of Design and Innovation Consulting
Authors: Palm William J. , Whitney Daniel E.
Published: September 2013

Although the risks and rewards of outsourcing product design have been argued extensively in the literature, little hard data on project outcomes exist to inform the discussion, and even these are methodologically suspect. To address this gap, this paper uses novel random sampling techniques to locate projects and measure the distribution of project outcomes in one particular type of design outsourcing, domestic design consulting. The results suggest that design consulting outcomes are generally good but vary significantly between projects and consultancies. Overall rates of product commercialization and market success compare favorably to results previously reported for in-house product design, and client satisfaction levels are comparable to those of other service industries.
Design and Manufacturing of Embedded Pneumatic Actuators for an MRI-Compatible Prostate Cancer Binary Manipulator
Authors: Miron Geneviève , Girard Alexandre , Plante Jean-Sébastien , Lepage Martin
Published: September 2013

Magnetic Resonance Imaging (MRI) compatible robots can assist physicians in precisely inserting biopsy needles or therapeutic instruments directly into millimeter-size tumors using MR imaging feedback. MRI systems although present a challenging environment, including high magnetic fields and limited space, making the development of MRI-compatible robots complex. This paper presents an MRI-compatible pneumatic actuation technology consisting of molded polymer structures with embedded air-muscle, operated in a binary fashion. While having good positioning accuracy, the technology presents advantages of compactness, perfect MRI-compatibility, simplicity, and low cost. Here we specifically report the design and validation of a transperineal prostate cancer manipulator prototype having 20 embedded air-muscles distributed in four star-like polymer structures. Structures are made of silicone elastomer, using lost-core injection molding. The molded compliant joints of the muscles eliminate sliding surfaces, for low motion hysteresis and good repeatability. A simple and effective two-level design method for polymer air-muscles is proposed, using a manipulator model and three muscle models: geometrical, finite elements and uniaxial analytic. Binary control of each air-muscle assures stability and accuracy with minimized costs and complexity. The manipulator is tested MRI-compatible with no effects on the signal-to-noise ratio and, with appropriate image feedback, reaches targets with repeatability and accuracy under 0.5 mm. The embedded approach reveals to be a key feature since it reduces hysteresis errors by a factor of 6.6 compared to a previous non-embedded version of the manipulator. The successful validation of this binary manipulator opens the door to a new design paradigm for low cost and highly capable pneumatic robots, specifically for the intra-MRI manipulation.
Vibration Suppression in a Tension-Aligned Structure Through Sequential Application and Removal of Constraints
Authors: Cai Tingli , Mukherjee Ranjan , Diaz Alejandro R.
Published: September 2013

We present an efficient method for vibration suppression in a tension-aligned array structure using constraint actuators. The primary role of constraint actuators is to cyclically apply and remove constraints such that vibration energy is efficiently funneled into high-frequency modes of the structure, where it can be dissipated quickly and naturally due to high rates of damping. A cycle of constraint application and removal can never add energy and hence the method can potentially achieve vibration control without accurate knowledge of the system states. The vibration control methodology is applied to a tension-aligned array structure supported by a structure in compression. Our approach for vibration suppression has the potential to positively influence the development of tension-aligned architectures which are contemplated for large precision apertures in space.
Design of Crashworthy Structures With Controlled Energy Absorption in the HCA Framework
Authors: Bandi Punit , Schmiedeler James P. , Tovar Andrés
Published: September 2013

This work presents a novel method for designing crashworthy structures with controlled energy absorption based on the use of compliant mechanisms. This method helps in introducing flexibility at desired locations within the structure, which in turn reduces the peak force at the expense of a reasonable increase in intrusion. For this purpose, the given design domain is divided into two subdomains: flexible (FSD) and stiff (SSD) subdomains. The design in the flexible subdomain is governed by the compliant mechanism synthesis approach for which output ports are defined at the interface between the two subdomains. These output ports aid in defining potential load paths and help the user make better use of a given design space. The design in the stiff subdomain is governed by the principle of a fully-stressed design for which material is distributed to achieve uniform energy distribution within the design space. Together, FSD and SSD provide for a combination of flexibility and stiffness in the structure, which is desirable for most crash applications.
Foot Contact Interactions of a Clock Torqued Spring-Loaded Inverted Pendulum
Authors: Riddle Steven , Seipel Justin
Published: September 2013

The clock-torqued spring-loaded inverted pendulum (CT-SLIP) model describes the robust dynamic stability properties observed in most animals and some legged robots. However, the model’s behavior is sensitive to changes in liftoff conditions such as those experienced on realistic terrain. Here the incorporation of friction at the foot-ground interface is explored on the CT-SLIP model with specific interest in improving the transient center-of-mass dynamics. Multiple friction models are presented and tuned to reflect a periodic center-of-mass gait. The transient dynamics with friction are analyzed in comparison to the CT-SLIP model and improvements to the settling time and disturbance rejection were found. This addition of foot-ground contact friction may allow for better understanding of center-of-mass system dynamics on realistic terrain.