bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of an Integrated AFS/ACD Control System to Enhance 4WD Vehicles Dynamics and Stability
Authors: Goodarzi Avesta , Arabi Samaneh , Esmailzadeh Ebrahim
Published: March 2011

An integrated vehicle dynamic control system for a four-wheel drive vehicle with an active front steering (AFS) and active centre differential (ACD), based on fuzzy logic control, is developed to improve the vehicle stability and its handling performance. The control system has a hierarchical structure consisting of two layers. A fuzzy logic controller is used in the upper layer to keep the yaw rate in its desired value. The yaw rate error and the side slip angle are applied to the upper controlling layer as the inputs, where the desired traction torque transfer ratio and the steering angle correction of the front wheels are the outputs. However, the ideal control effectors could not directly be the control inputs for the centre differential. Therefore, in the lower control loop, one should map the ideal control effectors to the physical control inputs for the centre differential by optimum dynamic traction force distribution. A nonlinear eight degree-of-freedom (DOF) vehicle model with the traction force distribution being utilized by a PI controller is considered. The simulation results illustrate considerable improvements have been achieved for the vehicle stability and handling performance through the integrated AFS/ACD control system.
Motion Control of a Piezoelectric Microprecision Positioner Using Diagonal Recurrent Neural Networks
Authors: Chen Jua-Liang , Chen Zong-Lin
Published: March 2011

The objective of this paper is to design a suitable controller for a piezoelectric microprecision positioner. The dimensions of this positioner are 150 mm × 150 mm × 10 mm and with X-Y-θZ three degrees of freedoms. Piezo-electric actuators are used to drive the positioner, which is constructed by flexure structures. In order to improve the short stroke of PZT, simple-levers are added to the structures. In this research, a diagonal recurrent neural networks (DRNN) controller is added to the system with aim to reduce the effect causes by the hysteresis, inaccurate system model and phase lag, and to save time for adjusting control gains for PID control. From the experimental results, it shows that the positioning errors for the X-axis, Y-axis, and θ-axis of continuous stepping test are less than 20 nm and 0.15 μrad. For the ramp tracking test, the tracking errors are less than 30 nm and 0.3 μrad. For the circular tracking test, the tracking error is less than 55 nm for both X- and Y-axis.
Robustness Analysis of Airfoil Performance
Authors: Lindstro¨m David E.
Published: March 2011

We demonstrate a technique to evaluate the aerodynamic robustness of a given blade profile which it is exposed to stochastic geometrical variation. The technique is based on random fields, with geometrical deviations continuously defined over the entire structure, with a prescribed statistical distribution function and a given correlation between these deviations. Control points are defined on the blade surface to model the blade geometry disturbances. At each control point a stochastic deviation is defined, which acts in the normal direction of the blade. By modeling disturbances in the normal direction instead of in the separate Cartesian directions, we automatically reduce the number of stochastic variables by a factor two. The perturbation variables are transformed via Karhunen-Loe`ve eigenvalue decomposition, giving stochastically independent variables. The robustness is finally estimated by a Monte Carlo simulation, where computational fluid dynamic simulations are performed to evaluate the resulting change in blade performance for given geometrical perturbations.
Estimating the Relative Importance of Iterative Information Coupling in the Design Process
Authors: Forootan M. Zaman , Freiheit Theodor
Published: March 2011

It is hard to plan tasks using tools for conventional project management in the complex process of product design and development when considering the essential exchange of information necessary in this interdisciplinary, concurrent engineering activity. The dependency structure matrix (DSM) is a useful tool to identify iterative information flows between processes and plan a strategy for managing them. Beyond quality, successful product development is dependent on its time and resource consumption, and the less iteration the project undergoes, the more successful it will be. Extending work done by others utilizing a binary DSM to minimize product development iteration, this paper presents a quantitative form of DSM, called QDSM, with a score of the relative importance of the information dependency of coupled iterations between system elements and through an example explains some of its applications and benefits. QDSM can be used by project managers to more effectively optimize project iteration.
Performance Analysis of a Relative Motion Based Magneto-Rheological Damper Controller for Suspension Seats
Authors: Huang Xiaoxi , Rakheja Subhash
Published: March 2011

A kineto-dynamic model of a suspension seat is formulated to account for contributions due to suspension kinematics. A regression-based model of a magneto-rheological (MR) fluid damper is also formulated and integrated to the suspension model. Two semi-active controllers based on the ‘sky-hook’ and ‘relative states’ are synthesized and simulations are performed to evaluate the shock and vibration performance of the MR suspension seat. The simulations are performed under an exponentially-decaying transient excitation with fundamental frequency in the vicinity of the suspension natural frequency, random excitations encountered at the seat base of vehicles with both low and high frequency components. The shock and vibration isolation properties of the suspension seat model are evaluated in terms of frequency-weighted rms accelerations and vibration dose values. Comparisons of the responses of the suspension seat model with ‘sky-hook’ and ‘relative states’ controllers revealed significant improvements compared to those of the passive suspension seat. The semi-active suspension seats could yield 19 to 40% reductions in the transmission of continuous vibration and 26 to 55% reduction of the shock motions. Both semi-active suspension models could considerably reduce the amount of end-stop impacts under high intensity excitations.
Development of a Product Family Analysis Toolkit for Systematic Benchmarking
Authors: Jain Avanti , Sarnobat Rahul , Simpson Timothy W.
Published: March 2011

As global markets saturate and competition intensifies, many manufacturers are focusing on benchmarking families of products alongside individual products to gain valuable insight and strategic advantage over their competitors. Unfortunately, the advantages of benchmarking families of products are often undermined by the limited capability of current benchmarking tools to assist in this process. While methods have been proposed for product family analysis and benchmarking, a major problem is the way in which the component details are collected, and few of the methods have been integrated together. Benchmarking and product family analysis is also time-consuming and subject to human variability since the process is typically done manually without the aid of software. To address these problems, we introduce the Product Family Analysis Toolkit (PFA Toolkit), which combines several popular benchmarking tools to streamline and standardize the process of product family benchmarking. We describe the toolkit’s features and capabilities and then discuss its functionality and usability. The advantages of automating the product family benchmarking process are discussed along with future work.
Development of a CMM Training System in Virtual Environments
Authors: Zhao Long , Peng Qingjin
Published: March 2011

Product inspection is a critical process of quality control in manufacturing. Coordinate measuring machine (CMM) is a type of precise inspection device widely used in manufacturing industry. The training of CMM operators is a time-consuming and costly processing, which has been identified as the primary intervention to improve the quality and reliability of the product inspection. Virtual Reality (VR) technology provides an intuitive and immersive user interface, which can be an efficient tool for the CMM training. Existing CMM software tools are either without VR user interface, or inefficient for a particular CMM application. This paper proposes a VR-based CMM training system. It uses virtual environments for trainees to operate and view the CMM motion and measurement processing. The VR-based training provides guides, instructions, and examples for trainees. The system design and implementation are discussed and illustrated.
Development of a Driving Simulator for Virtual Evaluation of Vehicle Dynamics
Authors: Sharaf A. M.
Published: March 2011

This paper delineates the conceptual algorithms of a driving simulator which is intended for vehicle performance evaluation and to act as a virtual platform for research studies and therefore eliminates the cost and dangerous of field testing. A virtual proving ground for vehicle testing has been devised through which virtual handling, traction and ride tests can be performed. A fully instrumented simulator cabin combining the driver and the vehicle simulation package is developed. Different vehicle configurations are simulated during typical sever manoeuvres which reflects the robustness and fidelity of the devised simulator.
Fingertip Force/Torque Sensor With High Isotropy and Sensitivity for Underwater Manipulation
Authors: Liang Qiaokang , Zhang Dan , Chi Zhongzhe , Ge Yunjian
Published: March 2011

Control strategies for robotic manipulators in underwater applications are still immature compared with the strategies of the manipulators on land. Part of the reason is that there is no precise force/torque information, which is essential to the close-loop control. Unlike the sensor applied on the ground, the sensors for underwater applications have to endure the high-pressure, low-temperature and corrosive environment. Therefore, aimed at obtaining the accurate interaction force/torque between underwater robot manipulators and objects, a novel four-dimensional fingertip force sensor is presented based on e-type membrane for underwater robot manipulators. A seal technique is described. Experimental results demonstrate the design could detect force/torque with good linearity, high sensitivity and weak couplings.
Innovative Approaches and Lesson Learned in Teaching CAD/CAE Applications Course
Authors: Tang Chin Pei , Xue Zhendan , Wang Yao
Published: March 2011

The application of Computer Aided Design and Engineering has been very popular in the engineering industry recently due to its usefulness in significantly reducing the time-to-market and cost involved within the design lifecycle of an engineering product. Despite the extensive availability of step-by-step manuals and tutorials to learn such tools, the emphasis of synergic utilization of such tools within the engineering design process has not been effectively addressed. Students often pay attention to learn how to use the tools instead of why to use such tools. In this paper, we present an innovative engineering education framework with various collaborative and interactive in-class activities and Web 2.0 tools to address the above issues in a senior undergraduate/graduate level CAD/CAE Applications course offered in University at Buffalo. Specifically, we categorize the approaches based the following components: (a) traditional lecture and computer labs, (b) team-based projects, (c) in-class activities, and (d) online course management tools. We show how the proposed approaches can be merged to the existing course syllabus in a synergic manner based on our experience. We also describe the rationale of the approaches and the expected outcome/improvements.
Symmetry Plane Detection for 3D CAD Volumes
Authors: Li Ke , Foucault Gilles , Le´on Jean-Claude
Published: March 2011

Symmetry properties of components have many applications during a product development process, including shape transformations for modification purposes, Finite Element Analysis (FEA), model retrieval, etc. This paper presents an algorithm to generate 3D model symmetry planes using the B-Rep model of CAD volumes. In the framework of CAD software, 3D models are described as B-Rep volume models. Design processes of volume models strongly rely on extrusion and revolution primitives from sketches containing essentially straight line segments and circular arcs. Hence, the boundary surfaces considered are planes, cylinders, cones, tori and spheres. The object boundary is effectively processed as an infinite set of points. Global symmetry properties of faces are derived to initiate the global symmetry planes of the object. To this end, the intersection curves between two adjacent faces are used to characterize possible global symmetry planes of the object. Then, the algorithm starts analyzing the symmetry properties of couple of faces. Subsequently, the candidate symmetry planes set up contains all the possible global symmetry planes. Finally, the symmetry properties of neighboring faces help determining robustly the global symmetry planes, whether there is a finite number or an infinite number.
Parameter Screening in Dynamic Computer Model Calibration Using Global Sensitivities
Authors: Drignei Dorin , Mourelatos Zissimos P. , Rebba Ramesh
Published: March 2011

Sensitivity analysis and computer model calibration are generally treated as two separate topics. In sensitivity analysis one quantifies the effect of each input factor on outputs, whereas in calibration one finds the values of input factors that provide the best match to a set of field data. In this paper we show a connection between these two seemingly separate concepts, and illustrate it with an automotive industry application involving a Road Load Acquisition Data (RLDA) computer model. We use global sensitivity analysis for computer models with transient responses to screen out inactive input parameters and make the calibration algorithm numerically more stable. Because the computer model can be computationally intensive, we construct a fast statistical surrogate for the computer model with transient responses. This fast surrogate is used for both sensitivity analysis and RLDA computer model calibration.
Similarity Computation for Knowledge-Based Sustainability Evaluation of Engineering Changes
Authors: Yang Seung-Cheol , Patil Lalit , Dutta Debasish
Published: March 2011

Systematic sustainability assessment of a proposed Engineering Change (EC) is, typically, a time-consuming process due to the complexity of typical products and the lifecycle-wide impact of a change. One approach to enable faster evaluation is the use of the knowledge from similar past ECs. In this paper, we present an approach based on research in psychology to calculate the similarity of Engineering Changes such that the retrieved ECs can be used to predict only the carbon footprint of the proposed EC. Product knowledge is structured, and there is no acceptable standard for representation. Therefore, we propose a measure that focuses on identifying and aligning corresponding components of the query and target representations. We apply the measure to a case of 14 Engineering Changes (91 matching problems) and compare the matches for relevance to evaluation of carbon footprint. The precision and recall are evaluated by comparing against carbon footprints obtained using commercial LCA tool.
Comparing Physical and Cyber-Enhanced Dissection: An Analysis From Multiple Perspectives
Authors: Grantham Katie , Moore-Russo Deborah , Lewis Kemper
Published: March 2011

Product dissection has evolved into a versatile pedagogical platform useful across the engineering curriculum. With the advent of digital, cyber, haptic, virtual, and immersive technologies, the opportunities to implement product dissection as an instructional tool increase dramatically. However, the effectiveness of cyber-enhanced dissection must be studied and the advantages and limitations of each type of platform must be understood in the context of achieving educational outcomes. In this paper, we first outline the history of dissection and carefully delineate the difference between physical, virtual, and cyber-enhanced dissection. We then study the impact of variations of cyber-enhanced (a blend of physical and virtual) dissection across two populations of sophomore engineering students at two universities using a number of exercises and data collection methods. We report on student perceptions regarding the affordances and disadvantages of physical vs. cyber-enhanced dissection. Students perceived the cyber-enhanced dissection exercises to be relevant to the students’ own professional preparation, to facilitate easier dissemination, to better align with emerging industrial practices, and to provide unique experiences not available in other courses the students had taken. Some potential drawbacks of cyber-enhanced dissection were also reported by students, including technology distracting them from the core educational objectives and overreliance on historical data of unknown origin. Although there are important tradeoffs between physical and cyber-enhanced dissection that need to be considered, using a blend of physical and virtual instructional tools may provide an effective platform to teach a wide range of engineering concepts across a curriculum.
Constraint Importance Mode Pursuing Sampling for Continuous Global Optimization
Authors: Kazemi Moslem , Wang G. Gary , Rahnamayan Shahryar , Gupta Kamal
Published: March 2011

Many engineering design problems deal with global optimization of constrained black-box problems which is usually computation-intensive. Ref. [1] proposed a Mode-Pursuing Sampling (MPS) method for global optimization based on a sampling technique which systematically generates more sample points in the neighborhood of the function mode while statistically covering the entire problem domain. In this paper, we propose a novel and more efficient sampling technique which greatly enhances the performance of the MPS method, especially in the presence of expensive constraints. The effective sampling of the search space is attained via biasing the sample points towards feasible regions and being away from the forbidden regions. This is achieved by utilizing the incrementally obtained information about the constraints, hence, it is called Constraint-importance Mode Pursuing Sampling (CiMPS). According to intensive comparisons and experimental verifications, the new sampling technique is found to be more efficient in solving constrained optimization problems compared to the original MPS method. To the best of our knowledge, this is the first metamodel-based global optimization method that directly aims at reducing the number of function evaluations for both expensive objective functions and constraints.
Equivalent Mechanisms Techniques for Redesign of a Spherical Surgical Tool Manipulator
Authors: Nelson Carl A. , Zhang Xiaoli
Published: March 2011

In the design of robotic manipulators for minimally invasive surgery (MIS), the spherical mechanism is a very important kinematic entity, since it can be used to mimic the constraint that the incision point provides to the surgical tool. In previous research by the authors, a bevel-gear-based spherical manipulator was designed whose actuators could be located on a fixed base link. In this paper, concepts of mechanism equivalency are applied to improving the manipulator design. The guidelines arrived at in this work can inform design of future spherical manipulators, especially those created with surgical tool manipulation in mind.
The Dimensional Synthesis of the Linear Delta Robot for a Force-Feedback Device
Authors: Cardou Philippe , Laurendeau Denis , Beaulieu Luc , Be´langer Luc , Carette Alexandre
Published: March 2011

We perform the dimensional synthesis of a parallel manipulator to be used as a force-feedback device in a virtual reality application for surgeon training in prostate brachytherapy. For such brachytherapy operations, the characteristics of the required workspace point towards the architecture of the linear DELTA robot to be used as the force-feedback device to the surgeon. In this paper, we address the dimensional synthesis of the linear DELTA robot for the prescribed workspace. To this end, we propose the minimum relative kinematic sensitivity as an objective function, a kinematic performance index that is different from most of the commonly used metrics, i.e., manipulability and dexterity. The minimum relative kinematic sensitivity represents the ratio of the minimum to the maximum effect of a unity-bounded set of actuator displacements on the moving-platform pose. These extremum sensitivities are computed independently over the prescribed workspace. Thence, the dimensional synthesis problem consists in finding the robot dimensions that maximize the minimum relative kinematic sensitivity, so it is guaranteed within a narrow interval over the prescribed workspace. This optimization problem is nonconvex, which poses a challenge from the computational point of view. However, because of symmetry in the mechanism and other simplifications, the number of optimization variables is reduced to four. This allows a reasonably fine discretization of the search domain, giving the designers confidence that the ensuing local optimum is close to the global optimum.
A Modified Continuous Reactive Tabu Search for Damage Detection in Beams
Authors: Arafa Mustafa , Youssef Ayman , Nassef Ashraf
Published: March 2011

The use of vibration-based techniques in damage identification has recently received considerable attention in many engineering disciplines. While various damage indicators have been proposed in the literature, those relying only on changes in the natural frequencies are quite appealing since these quantities can conveniently be acquired. The identification of damage involves an optimization step where response of a continuously updated finite elements model (FEM) is compared with the response of the experimental measurements and error between both responses is minimized. In this paper it is shown that such error function is highly multi-modal and that the same response can be obtained by more than one damage scenario. In order to find these optima a hybrid optimization approach is developed which utilizes two components; namely. Modified Continuous Reactive Tabu Search (MCRTS) and Real Coded Genetic Algorithms. MCRTS, the primary component, is a meta-heuristic capable of finding several optima in a multi-modal search space, which suites the nature of the problem at hand. GAs, the secondary component, although a global optimizer, is used as a local optimizer that is fired in promising regions of the search space as identified by the major component (MCRTS). It is used in favor of direct search methods to account for the presence of minor local optima. In order to test the algorithm, several beams are manufactured and crack damages are induced using wire-cutting, and the natural frequencies are tested experimentally. Such beams have two locations that can give the same response. The developed algorithm managed to find the two sought-for optima consistently in several runs. This proves the merit of this approach as being capable of handling the problem at hand.
Vibration Control of Smart Functionally Graded Plate Bonded With PZT4 Sensor/Actuator Patches
Authors: Kargarnovin M. H. , Viliani N. S.
Published: March 2011

The vibration of FG plate embedded with PZT4 rectangular patches on the top and/or the bottom surface(s) as actuators/sensors is investigated. Based on the classical laminated plate theory, the governing differential equations of motion are derived under a variable electric charge. The equation of motion for PZT4 patch is obtained and solved. The effect of feedback gain and FGM volume fraction exponent on the plate frequency and its deflection are studied. It is noticed that increasing the feedback gain leads to the reduction of frequency and displacement. Moreover, by increasing the value of the FGM volume fraction exponent the resonant frequency decreases.
On the Static Workspace of Large Dimension Cable-Suspended Robots With Non Negligible Cable Mass
Authors: Riehl Nicolas , Gouttefarde Marc , Pierrot Franc¸ois , Baradat Ce´dric
Published: March 2011

In most studies on parallel cable-driven robots, cables are supposed to be massless and inextensible. However, in the case of large dimension robots, cable mass and elasticity cannot be neglected anymore. Based on a well-known cable static model which takes these characteristics into account, the formulation of the inverse kinematics of n cable/n-DOF cable-driven robots is presented. The consequences of this modeling on the usual static workspace definition is then discussed. Notably, as the tension in a cable is not constant, the maximal tension along the cable has to be found. An example of a planar 3 cable/3-DOF robot is used to highlight that, in some particular poses, the mobile platform can be in static equilibrium while some cables are hanging below the platform. Finally, new limiting factors for the definition of the static workspace are introduced and applied to the same planar robot example which shows the significance of taking into account cable mass and elasticity.
Statically Balanced Compliant Micro Mechanisms (SB-MEMS): Concepts and Simulation
Authors: Tolou Nima , Henneken Vincent A. , Herder Just L.
Published: March 2011

Compliant mechanisms play an important role in micro mechanical structures for MEMS applications. However, the positive stiffness of these mechanisms remains a significant drawback. This stiffness can be compensated by including a static balancing mechanism (SBM), resulting in a statically balanced compliant micro mechanism (SB-CMM). This paper presents concepts and simulation results of such mechanisms, which could be applied to MEMS (SB-MEMS). Two categories of SB-CMMs are presented for different situations: the balancing force and travel path are either (1) perpendicular to each other, or (2) parallel to each other. The presented concepts provide compliant mechanisms with a finite zero stiffness range at the start or at a further predefined position of the overall mechanism travel range, respectively. The simulation results confirm the validity and performance of the presented concepts, which have been optimized for further evaluation. Incorporation of these concepts can ultimately result in a reliable, smaller, and energy efficient microsystem, having a larger useful travel range.
Requirements for Semantic Web Applications in Engineering
Authors: Fowler David , Crowder Richard M. , Guan Tao , Shadbolt Nigel , Wills Gary
Published: March 2011

In this paper we describe some applications of Semantic Web technologies for the engineering design community. Specifically, we use Semantic Wikis to form a central knowledge base, which other applications then refer to. The developed applications include an advisor for performing Computational Fluid Dynamics simulations, a Semantic search engine, and an assistant for airfoil design. In the conclusions we discuss lessons learned and subsequently requirements for future systems.
An Efficient Tradeoff Approach for Topology Optimization With Manufacturing Constraints
Authors: Stro¨mberg Niclas
Published: March 2011

In this paper an efficient approach for generating tradeoff curves when performing topology optimization with manufacturing constraints is presented. By minimizing a new stiffness-volume ratio, or in-fact a new compliance-volume product, the tradeoff curve is generated by changing a new design parameter. The volume appearing in the objective is raised to the power of this new design parameter. In such manner different conceptual designs can be generated. By adopting a nested approach, the problem is easily solved by a simple numerical scheme. This is a nice feature of the approach which makes the numerical performance most efficient and robust. This feature makes it also easy to include manufacturing constraints by simply updating the move limits such that these constraints are satisfied. The design parametrization is done by the SIMP-model and patterns of checker-boards are prevented by adopting Sigmund’s filter. The efficiency of the approach is demonstrated by presenting tradeoff curves for both 2D- and 3D-problems.
Design of a Robotic Hand With a Biologically-Inspired Parallel Actuation System for Prosthetic Applications
Authors: Crawford Anthony L. , Perez-Gracia Alba
Published: March 2011

This paper presents the design of a robotic hand for prosthetic applications. The main characteristic of this robotic hand is its biologically-inspired parallel actuation system, which is based on the behavior/strength space of the Flexor Digitorum Profundus (FDP) and the Flexor Digitorum Superficialis (FDS) muscles. The design separates the strength space of the FDS and FDP muscles into a lighter strength region where finer manipulation and general approach tasks are executed, and a higher strength region where the more robust grasps are achieved. Two parallel actuator types and kinematic structures are designed to complement the requirements of both strength space regions. This unique structure is intended to be driven by electromyographical (EMG) signals captured at the surface of the skin. The direct relation between signal and actuation system lends itself well to interpreting the EMG signals from the FDP and FDS muscles into effective task execution, with the goal of helping the user to achieve a good approximation of the full capabilities associated with the human hand, without compromising strength, dexterity, appearance, or weight; which are common issues associated with prosthetic hands.
A Planar Spring-Loaded Cable-Loop-Driven Parallel Mechanism
Authors: Liu Hanwei , Gosselin Cle´ment , Laliberte´ Thierry
Published: March 2011

A novel architecture of planar spring-loaded cable-loop-driven parallel mechanism is introduced in this paper. By attaching springs to the cable loops, two degrees of freedom can be controlled using only two actuators. In this mechanism, spools are eliminated. Therefore, it is expected that the accuracy of this mechanism is improved compared with conventional cable-driven mechanisms making use of spools. The mechanism can be actuated using either linear sliders or rotary actuators driving the motion of a cable or belt. This paper presents the inverse kinematics and the static equilibrium equations for the new architecture. It is verified that the cables and the springs can be kept in tension within the workspace. Results of numerical simulations are also given.
Design and Modeling of Variable Stiffness Joints Based on Compliant Flexures
Authors: Palli Gianluca , Melchiorri Claudio , Berselli Giovanni , Vassura Gabriele
Published: March 2011

The development of safe and dependable robots for physical human-robot interaction is actually changing the way robot are designed introducing several new technological issues. Outstanding examples are the adoption of soft covers and compliant transmissions or the definition of motion control laws that allow a compliant behavior in reaction to possible collisions, while preserving accuracy and performance during the motion in the free space. In this scenario, a growing interest is devoted to the study of variable stiffness joints. With the aim of improving the compactness and the flexibility of existing mechanical solutions, a variable stiffness joint based on the use of compliant flexures is investigated. The proposed concept allows the implementation of a desired stiffness profile and range along with the selection of the maximum joint deflection. In particular, this paper reports a systematic procedure for the synthesis of a fully-compliant mechanism used as a non-linear transmission, together with a preliminary design of the overall joint.
Design of a Vibration-Based Energy Harvester With Adjustable Natural Frequency
Authors: Mansour Mohamed O. , Arafa Mustafa H. , Megahed Said M.
Published: March 2011

The recent years have witnessed a wealth of research on energy harvesting technologies. To maximize the output power, vibration-based energy harvesters are normally designed to have natural frequencies that match those of the excitation. This has spurred interest into the design of devices that possess tunable natural frequencies to cope with sources which exhibit varying frequencies. In this work, an energy harvester is proposed in the form of a base excited cantilever treated with a piezoelectric layer. The cantilever carries a tip mass in the form of a magnet which is placed in close proximity to another magnet with opposite polarity. Different values of axial tensions, and hence different natural frequencies, are obtained by adjusting the gap between the magnets. A dynamic model to predict the system performance is presented and verified experimentally. Based on the findings of this paper, natural frequencies ranging from 3.19–12 Hz were achieved.
Topology and Constraint Analysis of Reconfiguration in Metamorphic Mechanisms
Authors: Zhang Ketao , Dai Jian S. , Fang Yuefa , Zhu Zi-Qiang
Published: March 2011

This paper investigates the reconfiguration of the metamorphic mechanisms and proposes mechanism topology matrix, phase matrix and augmented adjacency matrix to identify variation of geometric and topological configurations. This is then used to investigate the two generic ways in the study of induced constraint change of the metamorphic mechanisms. The topological phase change of the metamorphic mechanisms correlative to the variable-axis revolute joints and link annex is hence investigated and constraint analysis is then presented in the working phases of the new metamorphic mechanisms.
APU FMEA Validation and Its Application to Fault Identification
Authors: Yang Chunsheng , Letourneau Sylvain , Zaluski Marvin , Scarlett Elizabeth
Published: March 2011

FMEA (Failure Mode and Effects Analysis) is a standard method to characterize and document product and process problems at the design phase. The FMEA is often delivered to the end user along with the product or system. However, once the system is deployed, the corresponding FMEA is rarely validated and updated. This is mainly due to the lack of method to validate and update FMEA. This paper argues that historical maintenance and operational data could be used to help address this problem. Building on data mining and database techniques, the paper introduces a FMEA validation and updating technique. The proposed technique derives statistics from real world historical operation and maintenance data and uses these statistics to update key FMEA parameters such as Failure Rate and Failure Mode Probability. The paper then shows how the validated FMEA can be used with data mining for fault detection and identification of root contributing component for a given failure mode or failure effect. The paper presents the developed methodology for FMEA validation and experimental results for fault identification. The results show that the updated FMEA can provide more reliable and accurate information that could benefit the decision-making process and improve maintenance efficiency.
A Multi-Axis Slicing Method for Direct Laser Deposition Process
Authors: Kanakanala Divya , Routhu Swathi , Ruan Jianzhong , Liu Xiaoqing Frank , Liou Frank
Published: March 2011

With multi-axis capability, direct laser deposition process can produce a metal part without the usage of support structures. In order to fully utilize such a capability, the paper discusses a slicing method for multi-axis metal deposition process. Using the geometry information of adjacent layers, the slicing direction and layer thickness can be changed as needed. A hierarchy structure is designed to manage the topological information which is used to determine the slicing sequence. Its usage is studied to build overhang type structure. With such a character, some overhang features such as holes, can be deposited directly to save the required machining operation and material cost, which improves the efficiency of the metal deposition process. Combined with direct 3D layer deposition technique, the multi-axis slicing method is implemented.
Teaching Creative Design by Integrating General Design Theory and the Pahl and Beitz Methodology
Authors: Tomiyama Tetsuo , Breedveld Paul , Birkhofer Herbert
Published: March 2011

The design methodology developed by Pahl and Beitz (P&B) is one of the most widely taught design methodologies. However, this methodology is not easy to correctly exercise for non-experienced designers such as students. At TU Darmstadt in Germany, a method was developed to make students to realize the background philosophy of P&B, to reduce misunderstanding and misuse of the method, and to help them to arrive at creative design. At TU Delft in the Netherlands, an experienced designer who works on designing mechanical medical devices developed a method to generate creative designs. Although independently developed, these two methods share some commonality and have a potential to improve design education towards creative design. This paper is an attempt to give a theoretical explanation why these two methods facilitate creative design based on General Design Theory.
Kinematically Excited Large Angle Tilting Actuator
Authors: Ya’akobovitz Assaf , Krylov Slava
Published: March 2011

We report on a novel architecture and operational principle of a large angle kinematically excited tilting micro actuator. The device transforms and amplifies small linear out-of-plane motion of a parallel-plate electrostatic transducer into a tilting motion of a plate. The device characterized by robust single layer architecture was fabricated using a silicon on insulator (SOI) wafer and common deep reactive ion etching (DRIE) based fabrication process. Experimental and model results collectively illustrate the feasibility and efficiency of the suggested actuation approach. The optical tilting angle of 37.5° was experimentally registered under relatively low actuation voltage of 100 V.
The Case for Urban Vehicles: Powertrain Optimization of a Power-Split Hybrid for Fuel Economy on Multiple Drive Cycles
Authors: Whitefoot John W. , Ahn Kukhyun , Papalambros Panos Y.
Published: March 2011

Designing vehicles specifically for city use is a topic of increasing interest in the transportation community. Hybrid vehicle design typically seeks to maximize fuel economy subject to acceleration performance and other constraints, based upon the expected driving needs of the average user. Fuel economy predictions are inaccurate when the vehicle’s expected and actual uses are different. This paper studies the variation in design and fuel economy for a vehicle with a power-split hybrid electric powertrain optimized on a range of U.S. Environmental Protection Agency drive cycles, from the high-speed US-06 cycle to the low-speed New York City cycle. Results show variation of up to 9.8% in fuel economy and up to 41% in electric motor size. The vehicle designed for the dense urban environment has the largest variation in fuel economy, whereas the other vehicles have more similar performance. These results imply that the urban vehicle is the least robust and offers motivation for developing urban-specific vehicles. This analysis provides only a lower bound on potential performance because it does not consider possible vehicle downsizing or other design changes to meet customer expectations in urban use.
Integration of TRIZ and Virtual Environments for Hemp Scutcher Design
Authors: Xu Jinke , Peng Qingjin , Chen Ying
Published: March 2011

TRIZ method provides useful theory for users to analyze and solve problems using a logic manner. It is widely used in different fields and has gained great success in machine design. Virtual reality (VR) is a computer generated environment with features of visualization and users’ interaction, which provides a cost-effective tool for product evaluation and design improvement. In this research, TRIZ is applied in the design of a new hemp scutcher prototype. With the assistance of VR technology, the design visualization and concept evolution are achieved in a virtual environment. A VR-based system is developed to evaluate the mechanism of the conceptual design, and to compare differences with traditional machines. The new design is supposed to have a better performance in terms of scale, product quality and energy efficiency.
The Monitoring of Information Transfers to Control Design Progress During Product Development
Authors: Grebici Khadidja , Hisarciklilar Onur , Thomson Vincent
Published: March 2011

Uncertainty and complexity are inherent characteristics of a modern product development process. Concurrent engineering necessitates the use of interim information that may be incomplete, provisional, inconsistent and unreliable for the purpose of the tasks at hand. Mechanisms that allow actors in the design process to exchange interim information while being able to estimate the remaining risk of rework is of great importance to ensure robust decision making and to realize continuous progress. However, product development processes are traditionally managed through the use of milestone, or earned value methods without enabling the measurement as well as the capture of progress according to the state of progress of design tasks. The present paper presents a new methodology for monitoring interim information transfers. The approach supports design process planners by providing them with a monitoring system to control when interim information should be released, with which pace, and at which point of progress. This takes into account the criticality of information that is one of the main drivers of rework risk.
Force-Displacement Model of the FlexSuRe™ Spinal Implant
Authors: Stratton Eric , Howell Larry , Bowden Anton
Published: March 2011

This paper presents modeling of a novel compliant spinal implant designed to reduce back pain and restore function to degenerate spinal disc tissues as well as provide a mechanical environment conducive to healing of the tissues. Modeling was done through the use of the pseudo-rigid-body model. The pseudo-rigid-body model is a 3 DOF mechanism for flexion-extension (forward-backward bending) and a 5 DOF mechanism for lateral bending (side-to-side). These models were analyzed using the principle of virtual work to obtain the force-deflection response of the device. The model showed good correlation to finite element analysis and experimental results. The implant may be particularly useful in the early phases of implant design and when designing for particular biological parameters.
Improving Mobile Robot Step-Climbing Capabilities With Center-of-Gravity Control
Authors: Skonieczny Krzysztof , D’Eleuterio Gabriele M. T.
Published: March 2011

The Mars Exploration Rover Spirit will henceforth be a stationary science platform, as its current mobility capabilities have been unable to free it from a sand trap for several months. Mobility systems of future planetary exploration robots will need to reduce risk of entrapment, access more challenging terrain, and cover more ground than ever before. This work presents a novel center-of-gravity (CoG) control algorithm, designed to increase rover mobility over step obstacles. The control algorithm is applied to a mobile robot platform featuring a reconfigurable chassis / suspension system. The 6-wheeled platform is equipped with active wheel-walking degrees of freedom in addition to driving, steering, and passive suspension DoFs typical for such robots. The controller is based on a new concept introduced here, the Contact-Angle Adjusted Support Plane, and uses wheel-ground contact angles to place the CoG such that weight acting on wheels encountering difficult local terrain is reduced. Mobility analysis, using the detailed multibody dynamics simulator RCAST (Rover Chassis Analysis and Simulation Tool), shows that the control algorithm dramatically improves step-climbing ability. The CoG controller can increase the height of obstacle surmountable by a factor of 2 to 3. Wheel-step interaction modes, joint angle limits for wheel-walking DoFs, and other practical mechanical considerations are discussed in the context of a hardware prototype of the studied chassis design.
Inverse Solution to the Coupled Ordinary Differential Equation
Authors: Venkataraman P.
Published: March 2011

The identification of the actual form of the constant coefficient coupled differential equations and their boundary conditions, from two sets of discrete data points, is possible through a unique two-step approach developed in this paper. In the first step, the best Bezier function is fitted to the data. This allows an effective approximation of the data and the required number of derivatives for the entire range of the independent variable. In the second step, the known derivatives are introduced in a generic model of the coupled differential equation. This generic form includes two types of unknowns, real numbers and integers. The real numbers are the coefficients of the various terms in the differential equations, while the integers are exponents of the derivatives. The unknown exponents and coefficients are identified using an error formulation. Two examples are solved. The given data is exact, smooth and they represent solutions to coupled linear differential equations. The solution is obtained through discrete programming. Three methods are presented. The first is limited enumeration, which is useful if the coefficients belong to a limited set of discrete values. The second is global search using the genetic algorithm for a larger choice of coefficient values. The third uses a state space integrator driven by the genetic algorithm, to minimize the error between known data and that obtained from numerical integration.
Multi-Objective Optimization in Industrial Robotic Cell Design
Authors: Feng Xiaolong , Wa¨ppling Daniel , Andersson Hans , O¨lvander Johan , Tarkian Mehdi
Published: March 2011

It has become a common practice to conduct simulation-based design of industrial robotic cells, where Mechatronic system model of an industrial robot is used to accurately predict robot performance characteristics like cycle time, critical component lifetime, and energy efficiency. However, current robot programming systems do not usually provide functionality for finding the optimal design of robotic cells. Robot cell designers therefore still face significant challenge to manually search in design space for achieving optimal robot cell design in consideration of productivity measured by the cycle time, lifetime, and energy efficiency. In addition, robot cell designers experience even more challenge to consider the trade-offs between cycle time and lifetime as well as cycle time and energy efficiency. In this work, utilization of multi-objective optimization to optimal design of the work cell of an industrial robot is investigated. Solution space and Pareto front are obtained and used to demonstrate the trade-offs between cycle-time and critical component lifetime as well as cycle-time and energy efficiency of an industrial robot. Two types of multi-objective optimization have been investigated and benchmarked using optimal design problem of robotic work cells: 1) single-objective optimization constructed using Weighted Compromise Programming (WCP) of multiple objectives and 2) Pareto front optimization using multi-objective generic algorithm (MOGA-II). Of the industrial robotics significance, a combined design optimization problem is investigated, where design space consisting of design variables defining robot task placement and robot drive-train are simultaneously searched. Optimization efficiency and interesting trade-offs have been explored and successful results demonstrated.