bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Design Methodology of Common Components for a Class of Products: Its Foundations and Promise
Authors: Fujita Kikuo , Yoshioka Shin’ichi
Published: June 2008

This paper discusses the optimal design of common components used for a class of products. While simultaneously designing multiple products has become an important concept in manufacturing in these days, alliances involved in such activities are extended from the traditional form. This means the existence of a chance that an integrator designs a set of components apart from particular products or a supplier commonalizes components independently from integrators. That is, any methodology for simultaneously designing a set of components becomes necessary behind ones for simultaneously designing a set of products. This paper formulates the design problem of common components as an optimization problem, investigates the condition of optimal design through the tradeoff among the level of system-level performance, the number of different components, etc. Then a computational procedure is configured for optimizing the commonalization of components apart from designing a particular set of products by using multivariate analysis, an optimization code based on mini-max operation and a genetic algorithm for constrained nonlinear mathematical programming. Finally the proposed optimization procedure is preliminarily applied to a design problem of liftgate dumpers for passenger cars for demonstrating the meaning of the levels of optimal design and tradeoff structure.
Internet Based Framework to Perform Automated FEA on User Customized Products
Authors: Siddique Zahed , Ninan Jiju A.
Published: June 2008

Designing family of products require analysis and evaluation of performance for the entire product family. In the past, products were mainly mass-produced hence the use of CAD/CAE was restricted to developing and analyzing individual products. Since the products offered using a platform approach include a variety of products built upon a common platform, CAD/CAE tools need to be explored further to assist in customization of products according to the customer needs. In this paper we investigate the development of a Product Family FEA (PFFEA) module that can support FEA analysis of user customized product families members. Customer specifications for family members are gathered using the internet, users are allowed to scale and change configurations of products. These specifications are then used to automatically generate 3D solid models of the product and then perform FEA to determine feasibility of the customer specified product. In this paper, development of the PFFEA module is illustrated using a family of lawn trimmer and edger. The PFFEA module uses Pro/E to generate the solid model and ANSYS as the base FEA software.
Dimensional Adjustment for Assemblability of Rapid Protoyped Parts
Authors: ElMaraghy Hoda A. , Nassef Ashraf O. , ElMaraghy Waguih H.
Published: June 2008

Recent advances in rapid prototyping technology make it a useful tool in assessing the early designs of not only individual parts but also assemblies. These rapid assemblies should allow the designers to evaluate the desired functional requirements for the actual fabricated parts. However, the rapid prototyping errors, especially shrinkage, make it difficult to emulate such functional requirements in the prototype. This paper presents an algorithm for the optimal adjustment of the nominal dimensions of rapid prototyped parts to maximize the probability of adherence to the assembly functional requirements. The proposed modification of the nominal dimensions compensates for shrinkage. In addition, the algorithm preserves the general shape of the parts. Real coded genetic algorithms are used to maximize the probability of adhering to those requirements and a truncated Monte Carlo simulation is used to evaluate it. Several examples have been used to demonstrate the developed algorithm and procedures. Guidelines have been presented for the applicability of this adjustment method for various types of fits. The proposed method allows the designers to experience more realistically the intended fit and feel of actual manufactured parts assemblies.
Assembly Synthesis With Subassembly Partitioning for Optimal In-Process Dimensional Adjustability
Authors: Lee Byungwoo , Saitou Kazuhiro
Published: June 2008

Achieving the dimensional integrity for a complex structural assembly is a demanding task due to the manufacturing variations of parts and the tolerance relationship between them. While assigning tight tolerances to all parts would solve the problem, an economical solution is taking advantage of small motions that joints allow, such that critical dimensions are adjusted during assembly processes. This paper presents a systematic method that decomposes product geometry at an early stage of design, selects joint types, and generates subassembly partitioning to achieve the adjustment of the critical dimensions during assembly processes. A genetic algorithm (GA) generates candidate assemblies based on a joint library specific for an application domain. Each candidate assembly is evaluated by an internal optimization routine that computes the subassembly partitioning for optimal in-process adjustability, by solving an equivalent minimum cut problem on weighted graphs. A case study on a 3D automotive space frame with the accompanying joint library is presented.
Analytical Target Setting: An Enterprise Context in Optimal Product Design
Authors: Cooper Adam B. , Georgiopoulos Panayotis , Kim Hyung Min , Papalambros Panos Y.
Published: June 2008

Engineering design decisions have more value and lasting impact if they are made in the context of the enterprise that produces the designed product. Setting targets that the designer must meet is often done at a high level within the enterprise, with inadequate consideration of the engineering design embodiment and associated cost. For complex artifacts produced by compartmentalized hierarchical enterprises, the challenge of linking the target setting rationale with the product instantiation is particularly demanding. The previously developed analytical target cascading process addresses the problem of translating supersystem design targets into design targets for all systems in a multilevel hierarchically structured product, so that local targets are consistent with each other and allow top targets to be met as closely as possible. In this article the process of rigorously setting the supersystem targets in an enterprise context is explored as a model-based approach termed “analytical target setting.” The effectiveness of linking analytical target setting and cascading is demonstrated in an automotive truck vehicle example.
Multi-Objective Configuration Optimization With Vehicle Dynamics Applied to Midsize Truck Design
Authors: Miao Yi , Blouin Vincent Y. , Fadel Georges M.
Published: June 2008

Recent improvements in vehicle propulsion systems, such as hybrid electric and fuel cells, demand new configuration solutions that may be totally different from conventional designs. Packaging of vehicle components is still a new area of research. This paper describes a configuration optimization method based on a multiple objective genetic algorithm. The method is applied to configuration optimization of a mid-size truck, in which two objectives are considered: ground clearance and dynamic behavior. A vehicle packaging model was developed using the commercial CAD software, ACIS, to analyze interference among vehicle components. An eight-degree of freedom model was used to analyze the dynamic behavior of a given configuration for the J-turn maneuver. Parallel computation technology was also incorporated to accelerate the optimization process. The applicability of this method is discussed and exemplified with the design of a mid-size truck for two propulsion systems: conventional diesel and hybrid diesel electric. A set of Pareto solutions is generated in which tradeoff decisions can be made to select a final design.
A New Mathematical Model for Geometric Tolerances as Applied to Axes
Authors: Bhide S. , Davidson J. K. , Shah J. J.
Published: June 2008

A new mathematical model for representing the geometric variations of lines is extended to include form and accumulation (stackup) of tolerances in an assembly. The model is compatible with the ASME/ANSI/ISO Standards for geometric tolerances. Central to the new model is a Tolerance-Map©, a hypothetical volume of points which corresponds to all possible locations and variations of a segment of a line (the axis) which can arise from tolerances on size, position, orientation, and form. Every Tolerance-Map is a convex set in a metric space. The new model makes stackup relations apparent in an assembly, and these can be used to allocate size and orientational tolerances; the same relations also can be used to identify sensitivities for these tolerances. All stackup relations can be met for 100% interchangeability or for a specified probability. Much of the detail in this paper would probably reside internally to software for designers, yet would not be included in the interface; its workings should be invisible to the user.
Tolerance Synthesis of Mechanisms: A Robust Design Approach
Authors: Caro Ste´phane , Bennis Fouad , Wenger Philippe
Published: June 2008

The paper aims at dimensioning a mechanism in order to make it robust, and synthesizing its dimensional tolerances. The design of a mechanism is supposed to be robust when its performance is as little as sensitive as possible to variations. First, a distinction is made between three sets to formulate a robust design problem; (i) the set of Design Variables (DV) whose nominal values can be selected between a range of upper and lower bounds, they are controllable; (ii) the set of Design Parameters (DP) that cannot be adjusted by the designer, they are uncontrollable; (iii) the set of performance functions. DV are however under uncontrollable variations although their nominal value can be adjusted. Moreover, two methods are described to solve robust design problems. The first method is explicit and solves problems that aim at minimizing variations in performance. The second method, an optimization problem, aims at optimizing the performance and minimizing its variations, but only when the ranges of variations in DV and DP are known. Besides, we define and compare some robustness indices. From the explicit method, we develop a new tolerance synthesis method. Finally, three examples are included to illustrate these methods: a damper, a two-dof and a three-dof serial positioning manipulator.
A Methodology for the Study of the Effects of Communication Method on Design Review Effectiveness
Authors: Ostergaard Karen J. , Wetmore William , Summers Joshua D.
Published: June 2008

It is necessary for product teams with diverse expertise to communicate during the product development process, notably during design reviews. As this expertise may be distributed across different geographic locations of an organization, design review teams are facing new challenges in effective communication. This paper presents the results of a controlled user study devised to examine the effectiveness of various communication methods for design reviews. Speech only, text only, and free communication methods were chosen to simulate current technologies commonly used in situations of geographic distribution. Primary results from the study include: group design reviews were approximately twice as effective as individual design reviews; free communication produced greater perceived effectiveness than speech only communication, speech only communication produced greater perceived effectiveness than text only communication; and certain personality factors, such as extroversion and intuition, may have contributed to higher productivity in design review teams.
Knowledge Intensive Collaborative Decision Support for Design Process
Authors: Zha Xuan F. , Sriram Ram D. , Lu Wen F.
Published: June 2008

Engineering design is essentially a collaborative decision-making process that requires rigorous evaluation, comparison and selection of design alternatives and optimization from a global perspective on the basis of different classes of design criteria. Increasing design knowledge and supporting designers to make right and intelligent decisions can achieve the improvement of the design and design efficiency. This paper develops a knowledge-based decision support model and framework that can be extensively applied for an engineering system, which allows for the seamless / smooth integration of collaborative product development with optimal product performance. The developed hybrid robust design decision support model quantitatively incorporates qualitative design knowledge and preferences of multiple, conflicting attributes stored in a knowledge repository so that a better understanding of the consequences of design decisions can be achieved from an overall perspective. Two new concepts and mechanisms, transforming bridge and regulatory switch, are introduced in integration of decision support models. The results of this work provide a framework for an efficient decision support environment involving distributed resources to shorten the realization of products with optimal life-cycle performance and competitiveness. The developed methodology and framework are generic and flexible enough to be used in a variety of decision problems. Case application and studies for concept evaluation and selection in design for mass customization are provided.
Analysis of Support Vector Regression for Approximation of Complex Engineering Analyses
Authors: Clarke Stella M. , Griebsch Jan H. , Simpson Timothy W.
Published: June 2008

A variety of metamodeling techniques have been developed in the past decade to reduce the computational expense of computer-based analysis and simulation codes. Metamodeling is the process of building a “model of a model” that provides a fast surrogate for a computationally expensive computer code. Common metamodeling techniques include response surface methodology, kriging, radial basis functions, and multivariate adaptive regression splines. In this paper, we present Support Vector Regression (SVR) as an alternative technique for approximating complex engineering analyses. The computationally efficient theory behind SVR is presented, and SVR approximations are compared against the aforementioned four metamodeling techniques using a testbed of 22 engineering analysis functions. SVR achieves more accurate and more robust function approximations than these four metamodeling techniques and shows great promise for future metamodeling applications.
Introducing Rough Set for Design Space Exploration and Optimization
Authors: Shan Songqing , Wang G. Gary
Published: June 2008

Modern engineering design problems often involve computation-intensive analysis and simulation processes. Design optimization based on such processes is desired to be efficient, informative, and transparent. This work proposes a rough set based approach that can identify multiple subregions in a design space, within which all of the design points are expected to have a performance value equal to or less than a given level. The rough set method is applied iteratively on a growing sample set. A novel termination criterion is also developed to ensure a modest number of total expensive function evaluations to identify these sub-regions and search for the global optimum. The significances of the proposed method are two folds. First, it provides an intuitive method to establish the mapping from the performance space to the design space; given a performance level, its corresponding design region(s) can be identified. Such a mapping can be used to explore and visualize the entire design space. Second, it can be naturally extended to a global optimization method. It also bears potentials for more abroad applications to problems such as robust design optimization. The proposed method was tested with a number of test problems.
Level Set Models for Structural Topology Optimization
Authors: Wang Michael Yu , Wang Xiaoming
Published: June 2008

This paper presents a new model for structural topology optimization. We represent the structural boundary by a level set model that is embedded in a scalar function of a higher dimension. Such level set models are flexible in handling complex topological changes and are concise in describing the boundary shape of the structure. Furthermore, a gradient-based procedure leads to a numerical algorithm for the optimum solution satisfying specified constraints. The result is a 3D topology optimization technique with outstanding flexibility of handling topological changes, without resorting to homogenization-based relaxations that are widely used in the recent literature.
Topology Optimization of a Compliant Gripper Using Hybrid Simulated Annealing and Direct Search
Authors: Shalaby Mohamed M. , Hegazi Hesham A. , Nassef Ashraf O. , Metwalli Sayed M.
Published: June 2008

The present work introduces a new methodology for solving the topology optimization problem of a compliant gripper. A hybrid optimization technique is developed using simulated annealing as a random search method, while the simplex method (Nelder-Mead) is used as a direct search method. A new modified technique of motion from one search point to another based on the discrete nature of adding and/or removing a structural member is proposed. The traditional continuous simulated annealing technique is used to find the members’ heights. A discrete uni-variant search method is adopted following the simulated annealing and before the simplex method. This corresponds to about 14% of the number used in the old method and in the previous work in the literature, and about 86% of the optimization time is saved. The optimum design of a compliant mechanism is conducted for maximum flexibility and stiffness using the developed hybrid optimization technique.
A Face Clustering Method for a Hexahedral Meshing
Authors: Doi Jun , Yamada Atsushi , Inoue Keisuke
Published: June 2008

Finite element analysis has become a key technology for a design process of manufacturing industry. A hexahedral mesh is focused, because using a hexahedral mesh increases the quality of analysis. However it is very difficult problem to generate high quality hexahedral meshes, and there are many challenging research topics. Our goal is to develop a method to generate hexahedral meshes automatically to general volumes. Our method uses an intermediate model to recognize the input volume. The intermediate model is defined in the integer 3-dimensional space, and faces of the intermediate model are vertical to coordinate axes. Hexahedral mesh is generated by dividing the intermediate model into integer grids, and blocks of grids are projected into original volume. In this paper, we describe the method to generate a topology of the intermediate model. We use face clustering technique to generate the topology of the intermediate model. The faces of the input volume are clustered into 6 types; according to 3 coordinate axes and its direction, and clustered faces will be the faces of the intermediate model.
Smoothing of Noisy Laser Scanner Generated Meshes Using Polynomial Fitting and Neighborhood Erosion
Authors: Vieira Miguel , Shimada Kenji , Furuhata Tomotake
Published: June 2008

This paper presents a method for removing geometric noise from triangulated meshes while preserving edges and other intended geometric features. The method iteratively updates the position of each mesh vertex with a position lying on a locally fitted bivariate polynomial. The user selects the width of the vertex neighborhood, the order of the fitted polynomial, and a threshold angle to control the effects of the smoothing operation. To avoid smoothing over discontinuities, the neighborhood can be eroded by removing vertices with normals that deviate beyond a threshold from the estimated median normal of the neighborhood. The method is particularly suitable for use on laser scanner generated meshes of automobile outer body panels. Smoothing methods used on these meshes must allow C2 continuous equilibrium surfaces and must minimize shrinkage. Despite the abundance of existing smoothing schemes, none addresses both of these specific problems. This paper demonstrates the effectiveness of our method with both synthetic and real world examples.
A Study of Convergence in Decentralized Design
Authors: Chanron Vincent , Lewis Kemper
Published: June 2008

The decomposition and coordination of decisions in the design of complex engineering systems is a great challenge. Companies who design these systems routinely allocate design responsibility of the various subsystems and components to different people, teams or even suppliers. The mechanisms behind this network of decentralized design decisions create difficult management and coordination issues. However, developing efficient design processes is paramount, especially with market pressures and customer expectations. Standard techniques to modeling and solving decentralized design problems typically fail to understand the underlying dynamics of the decentralized processes and therefore result in suboptimal solutions. This paper aims to model and understand the mechanisms and dynamics behind a decentralized set of decisions within a complex design process. By using concepts from the fields of mathematics and economics, including Game Theory and the Cobweb Model, we model a simple decentralized design problem and provide efficient solutions. This new approach uses numerical series and linear algebra as tools to determine conditions for convergence of such decentralized design problems. The goal of this paper is to establish the first steps towards understanding the mechanisms of decentralized decision processes. This includes two major steps: studying the convergence characteristics, and finding the final equilibrium solution of a decentralized problem. Illustrations of the developments are provided in the form of two decentralized design problems with different underlying behavior.
A Concurrent Design Method for Multiple Cross-Sectional Automotive Body Frames Involving Discrete and Continuous Design Variables
Authors: Yoshimura Masataka , Nishiwaki Shinji , Izui Kazuhiro
Published: June 2008

As CAE (Computer Aided Engineering) applications become increasingly precise, the knowledge and technical skill required to operate such applications has become more highly specialized. However, such tools have not been utilized in the initial design process of mechanical products, where designers cannot construct detailed analytical models. This paper proposes a cross-sectional shape design optimization system that supports the initial design process for bar structures. The cross-sectional design problem is formulated as an eight-objective optimization problem that can be solved using genetic algorithms. A method for generating cross-sectional shapes satisfying designer-required characteristics is also proposed. These methods, which reduce the number of trial and error processes and product design failures, are expected to enable shortened product development lead-times.
Scenario Expression for Characterizing Failure Cases
Authors: Iino Kenji , Hatamura Yotaro , Shimomura Yuko
Published: June 2008

Mere collection of failure information and accident records do not effectively relay the knowledge associated with the case to the reader. We propose to collect data in a structured manner so the message is better transferred to the information receiver. We further developed a scheme that records the essence of each failure case in a sequence of predefined phrases displayed to the recorder in a hierarchy of phrases. We call the sequence the “scenario” of the event. Arranging the phrases in descending steps and supplementing it with an illustration and a key knowledge sentence composes the visual summary of the case. A glance at the visual summary and reading the scenario steps generate a good image of the case in the receiver’s mind. Among the predefined hierarchical phrases, we call those that express the cause of the event, failure cause phrases. Recording high level failure cause phrases from the hierarchy forces the event recorder to evaluate the root cause of the failure. To the top and second level (in the phrase hierarchy) failure cause phrases, we assigned 5-space vector components to characterize each phrase in terms of “knowledge”, “carefulness”, “judgment”, “organization”, and “nature”. This vector characterization of the failure cause phrases with the scenario allows us to further characterize each failure case as a linear combination of the predefined phrases. Once each failure case has its vector characterization, we can evaluate its similarity with other cases. Also, if we find the characterization of an individual, group, or organization in the same 5-space, we can warn about failure cases with similar characteristics that are likely to happen. The method is powerful in predicting failures so they can be avoided before happening.
Design Sensitivity Analysis of Nonlinear Shell Structure With Frictionless Contact
Authors: Choi Kyung K. , Yi Kiyoung , Kim Nam H. , Botkin Mark E.
Published: June 2008

A continuum-based shape and configuration design sensitivity analysis method for a finite deformation elastoplastic shell structure with frictionless contact has been developed. Shell elastoplasticity is treated based on the projection method that performs the return mapping on the subspace defined by the zero-normal stress condition. An incrementally objective integration scheme is used in the context of finite deformation shell analysis, wherein stress objectivity is preserved for finite rotation increments. The penalty regularization method is used to approximate the contact variational inequality. The material derivative concept is used to develop continuum based design sensitivity. The design sensitivity equation is solved without iteration at each converged load step. Numerical implementation of the proposed shape and configuration design sensitivity analysis is carried out using the meshfree method. The accuracy and efficiency of the proposed method is illustrated using numerical examples.
Genetic Range Genetic Algorithms to Obtain Quasi-Optimum Solutions
Authors: Arakawa Masao , Miyashita Tomoyuki , Ishikawa Hiroshi
Published: June 2008

In some cases of developing a new product, response surface of an objective function is not always single peaked function, and it is often multi-peaked function. In that case, designers would like to have not oniy global optimum solution but also as many local optimum solutions and/or quasi-optimum solutions as possible, so that he or she can select one out of them considering the other conditions that are not taken into account priori to optimization. Although this information is quite useful, it is not that easy to obtain with a single trial of optimization. In this study, we will propose a screening of fitness function in genetic algorithms (GA). Which change fitness function during searching. Therefore, GA needs to have higher flexibility in searching. Genetic Range Genetic Algorithms include a number of searching range in a single generation. Just like there are a number of species in wild life. Therefore, it can arrange to have both global searching range and also local searching range with different fitness function. In this paper, we demonstrate the effectiveness of the proposed method through a simple benchmark test problems.
Optimizing Optimization for Design Optimization
Authors: Krus Petter , Andersson Johan
Published: June 2008

Design optimization is becoming and increasingly important tool for design. In order to have an impact on the product development process it must permeate all levels of the design in such a way that a holistic view is maintained through all stages of the design. One important area is in the case of optimization based on simulation, which generally requires non-gradient methods and as a consequence direct-search methods is a natural choice. The idea in this paper is to use the design optimization approach in the optimization algorithm itself in order to produce an efficient and robust optimization algorithm. The result is a single performance index to measure the effectiveness of an optimization algorithm, and the COMPLEX-RF optimization algorithm, with optimized parameters.
Distributed Compliant Model for Efficient Dynamic Simulation of Systems With Frictional Contacts
Authors: Song Peng , Kumar Vijay
Published: June 2008

The use of Coulomb’s friction law with the principles of classical rigid body dynamics introduces mathematical inconsistencies. Specifically, the forward dynamics problem can have no solutions or multiple solutions. In these situations an explicit model of the contact compliance at the contact point can resolve these difficulties. In this paper, we introduce a distributed compliant model for dynamic simulation. In contrast to the rigid body model and the lumped model, our approach models each contact as a finite patch and uses half space approximation to derive solutions for the small deformations and force distributions in the contact patch. This approach leads to a linear complementarity problem formulation for the contact dynamics. The existence of an unique solution can be proved for both the lumped model in the point contact case and the more accurate, distributed model. Simulation algorithm that incorporates compliant contact models and linear complementarity theory are created and demonstrated through numerical examples.
Forward Problem Singularities of Manipulators Which Become PS-2RS or 2PS-RS Structures When the Actuators Are Locked
Authors: Di Gregorio Raffaele
Published: June 2008

The instantaneous forward problem (IFP) singularities of a parallel manipulator (PM) must be determined during the manipulator design and avoided during the manipulator operation, because they are configurations where the end-effector pose (position and orientation) cannot be controlled by acting on the actuators any longer, and the internal loads of some links become infinite. When the actuators are locked, PMs become structures consisting of one rigid body (platform) connected to another rigid body (base) by means of a number of kinematic chains (limbs). The geometries (singular geometries) of these structures where the platform can perform infinitesimal motion correspond to the IFP singularities of the PMs the structures derive from. This paper studies the singular geometries both of the PS-2RS structure and of the 2PS-RS structure. In particular, the singularity conditions of the two structures will be determined. Moreover, the geometric interpretation of their singularity conditions will be provided. Finally, the use of the obtained results in the design of parallel manipulators which become either PS-2RS or 2PS-RS structures, when the actuators are locked, will be illustrated.
Singularity Analysis of a Novel 4-DOFs Parallel Robot H4 by Using Screw Theory
Authors: Choi Hee-Byoung , Konno Atsushi , Uchiyama Masaru
Published: June 2008

The closed-loop structure of a parallel robot results in complex kinematic singularities in the workspace. Singularity analysis become important in design, motion, planning, and control of parallel robot. The traditional method to determine a singular configurations is to find the determinant of the Jacobian matrix. However, the Jacobian matrix of a parallel manipulator is complex in general, and thus it is not easy to find the determinant of the Jacobian matrix. In this paper, we focus on the singularity analysis of a novel 4-DOFs parallel robot H4 based on screw theory. Two types singularities, i.e., the forward and inverse singularities, have been identified.
An Integrated Virtual Validation System for Parallel Kinematic Machine Analysis Design
Authors: Zhang Dan , Wang Lihui , Lang Sherman Y. T.
Published: June 2008

Selecting a configuration for a machine tool that will best suit the needs of a forecast set of requirements can be a difficulty and costly exercise. This problem can now be addressed using an integrated virtual validation system. The system includes kinematic/dynamic analysis, kinetostatic model, CAD module, FEM module, CAM module, optimization module and visual environment for simulation and collision detection of the machining and deburring. It is an integration of the parallel kinematic machines (PKM) design, analysis, optimization and simulation. In this paper, the integrated virtual system is described in a detail, a prototype of a 3-dof PKM is modeled, analyzed, optimized and remote controlled with the proposed system. Some results and simulations are also given. Its effectiveness is shown with the results obtained by NRC-IMTI during the design of the 3-dof NRC PKM.
Design Optimization of 6-HTRT Parallel Robot Orientated on Workspace
Authors: Yu Hui , Wang Jinsong , Duan Guanghong , Sun Lining
Published: June 2008

In this paper an optimization method based on the Mechanics of Parallel Robots and orientated on workspace is conducted in the construction of 6-HTRT parallel robot. By analyzing the characteristics of specific workspace and setting up objective functions, optimizations are implemented on the design of parallel robot. As a result of the optimization design, the parallel robot not only figures the minimum overall size of robot structural, but also has workspace unrestricted by the limit range of Hooke joint’s conical angles. The restriction factors on workspace of 6-HTRT parallel robot are reduced thus the algorithm for motion control of the robot is simplified and the performance of the parallel mechanism is improved.
Optimal Integration of Smart Actuators in the Structure of Serial and Parallel Robot Manipulators to Enhance Speed and Tracking Precision
Authors: Rastegar J. , Yuan L. , Zhang J.
Published: June 2008

A method to determine optimal placement of smart (active) materials based actuators in the structure of robot manipulators for the purpose of achieving higher operating speed and tracking precision is developed. The method is based on the evaluation of the transmissibility of the displacement from the integrated smart actuators to the robot manipulator joint and end-effector displacements. By studying the characteristics of the Jacobian of the mapping function between the two displacements for a given position of the robot manipulator, the optimal positioning of the smart actuators that provides maximum effectiveness in eliminating high harmonics of the joint motion or the end-effector motion is determined. In robots with serial and parallel kinematics chains containing non-prismatic joints, due to their associated kinematics nonlinearity, if the joint motions were synthesized with low harmonic trajectories, the end-effector trajectory would contain high harmonics of the joint motions. Alternatively, if the end-effector motion were synthesized with low harmonic motions, due to the inverse kinematics nonlinearity, the actuated joint trajectories would contain a significant high harmonic component. As the result, the operating speed and tracking precision are degraded. By integrating smart materials based actuators in the structure of robot manipulators to provide small amplitude and higher frequency motions, the high harmonic component of the actuated joint and/or the end-effector motions are eliminated. As the result, higher operating speed and tracking precision can be achieved.
Influence of End-Effector Velocities on Robotic Manipulator Dynamic Performance: An Analytical Approach
Authors: Kim ChangHwan , Bowling Alan
Published: June 2008

This article explores the effect that end-effector velocities have on a nonredundant robotic manipulator’s ability to accelerate its end-effector as well as to apply forces/moments to the environment at the end-effector. The velocity effects considered here are the Coriolis and Centrifugal forces, and the reduction of actuator torque with rotor velocity, as described by the speed-torque curve. Analysis of these effects is accomplished using optimization techniques, where the problem formulation consists of a cost function and constraints which are all purely quadratic forms, yielding a nonconvex problem. An analytical solution, based on the dialytic elimination technique, is developed which guarantees that the globally optimal solution can be found. The PUMA 560 manipulator is used as an example to illustrate this methodology.
Analysis and Visualization of the Contact Force Solution Space for Multi-Limbed Mobile Robots With Three Feet Contact
Authors: Hong Dennis W. , Cipra Raymond J.
Published: June 2008

A new analytical method for determining, describing, and visualizing the solution space for the contact force distribution of multi-limbed robots with three feet in contact with the environment in three-dimensional space is presented. The foot contact forces are first resolved into strategically defined foot contact force components to decouple them for simplifying the solution process, and then the static equilibrium equations are applied to find certain contact force components and the relationship between the others. Using the friction cone equation at each foot contact point and the known contact force components, the problem is transformed into a geometrical one to find the ranges of contact forces and the relationship between them that satisfy the friction constraint. Using geometric properties of the friction cones and by simple manipulation of their conic sections, the whole solution space which satisfies the static equilibrium and friction constraints at each contact point can be found. Two representation schemes, the “force space graph” and the “solution volume representation,” are developed for describing and visualizing the solution space which gives an intuitive visual map of how well the solution space is formed for the given conditions of the system.
An Articulated Body Algorithm for Modelling and Simulation of an Underwater Vehicle Equipped With Manipulator Arm
Authors: Meghdari A. , Vossoughi G. R. , Hosseini M. Amir
Published: June 2008

In this paper, an efficient dynamic simulation algorithm is developed for an Unmanned Underwater Vehicle (UUV) with a N degrees of freedom manipulator. In addition to the effects of mobile base, the various hydrodynamic forces exerted on these systems in an underwater environment are also incorporated into the simulation. The effects modeled in this work are added mass, viscous drag, fluid acceleration, and buoyancy forces. Also the dynamics of thrusters are developed, and an appropriate mapping matrix dependent on the position and orientation of the thrusters on the vehicle, is used to calculate resultant forces and moments of the thrusters on the center of gravity of the vehicle. It should be noted that hull-propeller and propeller-propeller interactions are considered in the modeling too. Finally the results of the simulations are presented.
On the Robustness of Exactly Constrained Mechanical Assemblies
Authors: Hammond Alisha , Parkinson Alan R.
Published: June 2008

In recent years a number of practicing engineers have discussed the virtues of exactly constrained (EC) mechanical assemblies. While found by engineers in industry to have many benefits, EC designs remain somewhat unrecognized by academia. One reason for this minimal exposure may be the lack of a mathematical foundation for such designs. EC designs can be analyzed quite simply by understanding that they are statically determinate. This paper describes the history and current background for EC designs. It also begins to develop the mathematical foundation for EC design based on equations of equilibrium. Finally, it examines a Monte Carlo simulation of the effects of variation on EC assemblies vs. over-constrained assemblies. The EC design assembles 100% of the time, while the over-constrained design assembles only 50% of the time with greater error.
Similarity and Equivalence of Nutating Mechanisms to Bevel Epicyclic Gear Trains
Authors: Nelson Carl A. , Cipra Raymond J.
Published: June 2008

This paper addresses similarities between various nutating or wobbling mechanisms, especially kinematic similarities. A case is made for the generalization of several mechanisms into a mechanism “class” having common kinematic characteristics. This mechanism class is shown to be typified by bevel epicyclic gear trains. It is proposed that not only kinematic analysis, but static-force, power-flow, and efficiency analyses of mechanisms belonging to this “class” can be simplified by modeling them as bevel-gear trains. Simplified kinematic, force, and efficiency analyses are demonstrated for a novel wobbling speed reducer using this concept of “equivalent” geared mechanisms. The reduction in complexity of these analyses is the main motivation for this work.
Modularity: International Industry Benchmarking and Research Roadmap
Authors: Ishii Kosuke , Yang Tae G.
Published: June 2008

Increased time to market pressure and globally distributed engineering design environments demand a modular product structure that provides affordable life-cycle cost, high quality, and efficient development work tasks among the engineering enterprise, its partners and its suppliers. This project, in the long run, intends to develop a systematic methodology to achieve effective product modularity and work tasks that will enhance product development process. As an initial effort, we conducted a two-phased survey to explore the level of understanding and to benchmark modularity practice in various industries. The results indicate that the form and the extent of modularity practice depend on industry specific drivers, which are largely affected by strategic preferences, external uncertainties and tactical alternatives. This paper presents an introductory overview of modularity as defined in academia, presents the results of the survey, and then proposes potential directions for future research.
A Template for Design for Manufacture Guidelines
Authors: Stauffer Larry , Rule Robert , Ren Hong
Published: June 2008

DFM is often viewed as a body of useful information for improving the manufacturability of a part but without a step-by-step method. DFM guidelines are a primary resource providing guidance on how to improve the manufacturability of a part for the particular manufacturing process being used. One major problem with these guidelines is that there is not a consistent format for organizing them and understanding specifically what they are trying to accomplish. A standard DFM guideline structure would provide a consistent context for better understanding them. To this end we built a template, in the form of a taxonomy, based on variable cost of the part. We define the variable cost of the part to be comprised of its material, labor, and utility costs and for each of these, we defined factors that influence these costs. We claim that this template can provide a framework for organizing and presenting DFM guidelines in a context that the engineer can use in a more useful way. To provide more confidence in our template, we pursued a validation process based on the Content Analysis technique which is a way for making quantitative inferences about qualitative data, such as DFM guidelines. We used this technique to refine and validate the template which is presented in this paper. To provide further evidence and demonstrate the template’s usefulness, we provide two examples: the guidelines for electromechanical machining and guidelines for plastic injection molding.
Life Cycle Energy Analysis as a Method for Material Selection
Authors: Fitch Peder E. , Cooper Joyce Smith
Published: June 2008

This paper presents a method of performing Life Cycle Energy Analysis (LCEA) for the purpose of material selection. The method applies product analysis methods to the evaluation of material options for automotive components. Specifically, LCEA is used to compare material options for a bumper-reinforcing beam on a 1030 kg vehicle. From an energy perspective, glass fiber composites and high-strength steel beams performed best. This paper also presents a set of life cycle energy terms designed to clearly distinguish between energy consumption occurring during different phases of a product’s life cycle. In addition, this paper compares the results of the LCEA method to those of other energy analyses and demonstrates how different methods of varying thoroughness can result in different material selections. Finally, opportunities are identified for extending this type of analysis beyond both automotive components and energy consumption.
A Genetic Algorithm for Cost Estimating Turned Parts in an Interactive DFM Environment
Authors: Schrader R. Sebastian , Philpott Michael L. , Subbarao Gautam , Holmes Dale E.
Published: June 2008

This paper presents a method for the optimization of machining parameters, essential for the determination of an economical operating point for multi-pass turning operations. Optimal selection of cutting parameters such as the number of passes, depth of cuts, cutting speeds and feed rates are critical to process planning and cost optimization. This in turn creates a crossing point between product design and manufacturing. Generally, machining models are complex since they are highly non-linear. This research utilizes genetic algorithms as an optimization technique in order to maximize the accuracy of results, the computational achievement, and to minimize the influence of initial conditions and part geometry. A new approach that uses conventional turning process modeling along with genetic algorithms to rapidly search and optimize the feasible workspace is considered. The total production cost minimization is achieved by adding together the minimum cost of each roughing pass and the final finishing pass. In addition, the preventive tool replacement policy used in practice is incorporated. Finally, the results obtained for test cases are evaluated and compared.
On the Complexity of Mechanical Assemblies
Authors: Morse Edward P.
Published: June 2008

There is no doubt that today’s mechanical systems are complex. Mechanical systems tend towards greater complexity as each component interacts with a larger number of neighboring components. This structure of interaction permits function-sharing of the components — one of the hallmarks of creative design. Function-sharing is one of the interesting ways in which mechanical design differs from, for example, solid state circuit design. Assembly models that require fixed contact between components at specified locations to determine their relative positions will also have gaps that provide clearance between the components. The complexity of these assembly models is linear in the number of gaps, as the clearance at each gap is dependent on a single set of dimensions. However, if the assembly model is defined in terms of potential (vs. required) contacts between components, the complexity of the analysis increases dramatically. In this paper we describe the complexity of assemblies analyzed in a single direction (i.e. one-dimensional analyses) and propose a means of characterizing different types of assemblies.