bluuebunny/crossref_metadata_2025 huggingface dataset:
Shape Optimization of Double Curved Arch Dams With Spline Function in Shape Description Module
Authors: Behfar Seyed M. R.
Published: February 2021

Shape description is the first step of shape optimization. This paper shows the possibility of shape description with spline function for surfaces of a double curved arch dam. A mathematical formulation of the boundary of the structure is necessary for the optimization algorithm. A finite element model with 3-dimensional elements is used for structural analysis of the arch dam and its foundation. The optimization algorithm, a sequential quadratic programming (SQP), can be started from initial unfeasible points.
Stochastic Approximation Methods in Optimal Structural Design: The Use of Intermediate Variables
Authors: Marti Kurt
Published: February 2021

Reliability-based optimization methods in optimal structural design use mostly the following basic design criteria: I) Minimal weight (volume or costs) and II) high or reliability of the structure. Since, in practice, several parameters of the structure, e.g. elastic moduli, tolerances of structural dimensions, loads, are not given, fixed quantities, but random variables having a certain probability distribution P, a stochastic optimization problem will result from criteria (I), (II), which can be represented

min F(x) with F(x) := Ef(ω, x). (1)

x∇D

Stochastic approximation methods are considered for solving (1): The gradient estimators are obtained by the response surface methodology (RSM) where especially the improvement of the estimators by using so-called “intermediate” or “intervening” variables is considered.
Investigations Into the Experimental and Numerical Simulation of a Shaping Machine
Authors: Reddy Vijay , Rajeev P. T. , Ramamurti V. , Madhusudan R.
Published: February 2021

One of the main requirements for efficient and economical material removal is optimal machine tool design. The main objective of this paper is to investigate the dynamic characteristics of a shaping machine using finite element method. In the first part, experimentation and computation are combined to formulate and validate the mechanical model of the shaper. A parametric study is done in the second part. The main housing along with the ram of a typical shaper is analyzed during the process of shaping. This assembly is modeled using triangular shell elements. The eigenvalues and the eigenvectors are obtained. There is an acceptable degree of agreement between analytical results and the experimental observations. The cutting force is determined experimentally and using this the response of the shaping machine is determined. The dynamic acceleration response so obtained is compared with the experimentally obtained response. An exhaustive stress analysis is done. The system is sensitive to changes in certain parameters which are identified and analyzed, with optimization of the structural weight and machining accuracy being the criteria.
Structural Topology Optimization for Forced Frequency Vibrations
Authors: Soto Ciro A. , Yang R. J. , DeVries Richard
Published: February 2021

This work deals with the problem of computing the optimum topology of structures subject to a force frequency spectrum. The analysis is done in the frequency domain and the optimum topology is computed using the simplified density approach. Optimization formulation as well as the sensitivity analysis are discussed. An example showing the capabilities of the computational implementation is presented.
Robust Design for Fatigue Performance: Shot Peening
Authors: Esterman Marcos , Nevarez Ivan M. , Ishii Kosuke , Nelson Drew V.
Published: February 2021

Fatigue data usually display substantial scatter. The goal of this paper is to demonstrate how simulated variation in surface treatment processing parameters and material properties affect the predicted fatigue life (mean and scatter) of a component. This is achieved by applying robust design principles to fatigue life evaluation methods, using shot peening as the representative manufacturing process for this study. Analyzing changes in the appropriate fatigue performance quality characteristic due to variations in the process parameters and material properties will identify levels of the controllable process parameters which maximize the mean fatigue performance and minimize its scatter. The simulation predictions of this study are consistent with past experimental observations which show that compressive residual stress distributions tend to increase mean fatigue life and reduce its scatter for a component. Our results extend these observations by relating the increase in mean life and the reduction in scatter to the controllable manufacturing and design parameters. In addition, the intermediate measure of compressive zone depth is identified as a possible off-line production quality check that relates directly to the component fatigue performance (mean and scatter), as well as an aid to the designer to identify an appropriate surface treatment process. This study serves as an initial step in the development of a generalized methodology that can aid engineers with design for robust fatigue performance for other manufacturing processes.
Configuration Design With Neural Networks
Authors: Chawdhry Pravir K. , Potter Stephen E. , Culley Stephen J. , Burrows Cliff R.
Published: February 2021

This research examines a novel application of artificial neural networks (ANN) in engineering design. A NN-based learning technique is presented for generating configuration designs from functional requirements and basic domain concepts.

With functional requirements as input, an elementary neural network can learn simple domain design rules. The output of the network is a set of complex design functions, later transformed into configurations. The application of design rules provides a strategy to enable an efficient search for acceptable design configurations.

We validate the methodology in the domain of fluid power systems by a circuit simulation and analysis package Bathfp. This research is creating new insights into the practical realisation of an automatic configuration design process. It also sheds light on novel applications of neural networks.
Cooperatively Planning Sheet Metal Bending
Authors: Bourne David A. , Gupta Satyandra K. , Kim Kyoung H.
Published: February 2021

A cooperative planning system for bending sheet metal parts is presented by using a detailed example. In this example, two of subplanners (a robotic grasp planner and a tool selection planner) have conflicting results that prevent a timely solution. We show how these conflicts can be avoided by sharing constraints before the search process begins. In this discussion, we detail the decisions that are made by each of the subsystems. The resulting cooperative planner is able to solve difficult real-world planning problems, while reducing the time between design and production by 50 times from the current state of practice.
A New Numerical Approach to Model Surface Generation Through Wrapping
Authors: Oancea Victor G. , Oancea Nicolae
Published: February 2021

Several methods exist for the determination of profiles of cutting tools which work by wrapping. Most of these methods are based on the envelope theory and most often require cumbersome analytical formulations and the solution of equations not always easy to resolve. This work, based on the principle of minimal distance first proposed in a previous work of the second author, presents a new purely numerical method for the calculation of the active profile of the cutting tools which work by wrapping (direct problem) as well as for the estimation of the effectively generated surface on the workpiece when the tool is known at discrete points (inverse problem). The method can be used for any nonstandard profiles when an analytical description of the surfaces is not available. Several examples are shown for machining ball screws and parts of helical pumps.
Design for Manufacturability via Agent Interaction
Authors: Frost H. Robert , Cutkosky Mark R.
Published: February 2021

We describe an approach for making the capability of manufacturing processes manifest to designers starting with the earliest stages of geometry specification. The approach involves a dialogue among design and manufacturing agents over the Internet. The dialogue focuses on the specification and exchange of process capability models for establishing “design rules on-demand” to ensure manufacturability. The models include both declarative knowledge and, for those aspects of the process that are difficult to represent declaratively, platform-independent procedural code which is automatically loaded onto the designers’ machines. The approach is being implemented using agents, written in the Java2 language, which exchange feature-based capability models. The approach is being tested initially on machining and shape-deposition processes.
IVECS: An Interactive Virtual Environment for the Correction of .STL Files
Authors: Morvan Stéphane M. , Fadel Georges M.
Published: February 2021

The current trends towards fully integrated digital design processes depend on the use of physical mockups. Free Form Fabrication extracts data from Computer Aided Design software and transforms them into a tangible reality. Virtual Reality (VR) provides a remarkable complement to these techniques. The system presented responds to the needs to ensure accurate data and quick prototyping by providing visualization and edition of Computer Aided Design files in a Virtual Environment. This paper expands on the use of VR to virtually prototype artifacts represented by .STL files. It describes different techniques to interact with the object in the VE. Besides manipulating the object, various methods to display the triangles generated by tessellation are detailed and ways to correct the files are illustrated.
Value Implications of Green Design: Case Study of a Videocassette
Authors: Kopp Anne-Claire , Sturges Robert H.
Published: February 2021

Recent concern for the environment has caused growing attention to recycling, both using recycled materials to make products and recycling products after use. Although environmentalists may be eager to buy recycled/recyclable products, other consumers may not be so easily convinced. It may also be difficult to convince manufacturers that it is beneficial to develop green products. This paper supports a joint project between engineering and marketing disciplines to determine the cost and value of an environmentally designed product. Specifically, this paper evaluates the resources spent to manufacture a green videocassette in comparison with a standard videocassette by performing a resource analysis. This analysis estimates the cost, time and energy necessary to produce both videocassettes. This paper also compares the value of the videocassettes in terms of performance and physical attributes.
Computation of Voxel Maps Containing Tool Access Directions for Machining Free-Form Shapes
Authors: Tangelder Johan W. H. , Vergeest Joris S. M. , Overmars Mark H.
Published: February 2021

An algorithm that derives tool access directions for machining free-form shapes is presented. A free-form shape to be machined is given by a preliminary B-spline model. We allow that the B-spline surface data are as inaccurate as the user-selected geometric accuracy of the prototype to be machined. Using surface sampling a visibility voxel map is obtained. From this map a voxel map is derived that contains per voxel a set of tool access directions. From the obtained voxel map regions can be selected that can be machined with a fixed tool access direction per region.
Genetic Planner to Support DFA Assemblability Evaluation: Insights on Integrated Design and Planning for Assembly
Authors: Sebaaly Milad Fares , Fujimoto Hideo
Published: February 2021

Several Design for Assembly (DFA) methodologies have already been introduced both in research and industry, among which methodologies having quantitative assemblability evaluations are more favored in industry. The evaluation criteria involved in such quantitative measures are only concerned with the difficulty of performing assembly operations one by one. These measures are then combined by a formula to find the total product evaluation. Accordingly, the designer can improve the total assemblability by redesigning the parts that caused bad measures. It can be observed that a major effect of cascading several assembly operations in a certain order on the remaining operations to complete the product assembly is neglected by most DFA evaluation methodologies. Actually, this effect might result in serious difficulties while generating the assembly sequence usually done at a later stage in most industrial firms. To overcome these difficulties, this paper introduces some elementary insights to the integration of assembly design and planning. A systematic feature-based method is introduced to find the precedence assembly constraints and the global evaluation constraints resulting from operations cascading orders. A modified genetic algorithm that finds the best assembly sequence based on these constraints and on the traditional DFA evaluations is then introduced to be included in the DFA procedure. This genetic planner generates a more representative evaluation of the product assemblability by considering the effects of operations orders. As a result, feedback reflecting the actual assembly process difficulties can be given to the designer to improve the product design, while simultaneously generating the best sequence to assemble the product.
Gear Shaft Design Process by Using Object-Oriented Methods
Authors: Heikkinen Ari , Korpela Tapio , Leinonen Tatu
Published: February 2021

Ideas introduced in this paper have been applied in a development process of a design system for a Finnish gear manufacturer, Santasalo Ltd. Main products of the company are standard catalog gears, tailored products (standard gears with special requirements of the customer) and special gears. Our first application in this project has been a manufacture oriented shaft design, which is knowledge-based and included in commercial CAD software.
Towards Life-Cycle Fastening and Joining Cost Optimization Using Genetic Algorithms
Authors: Shu Lily H. , Flowers Woodie C.
Published: February 2021

This paper extends from our previous results which suggest that fastening and joining methods preferred for assembly and scrap-material recycling do not necessarily facilitate remanufacture. We identify, through collaboration with three remanufacturing companies, primary factors that determine the life-cycle fastening and joining cost of products that are remanufactured. These factors, that also determine life-cycle joint reliability, are the fastening or joining method specified during design, the disassembly and reassembly method used during remanufacture, and the repair policy. A reliability model was applied to describe the failure characteristics of the joint so that part failure and replacement costs can be estimated over a specified length of product service. We then present an illustrative sample search space and the resulting life-cycle costs. A larger search space would require the use of optimization methods to minimize life-cycle costs. The fastening and joining plan, consisting of the above three factors, is represented for genetic algorithm optimization to be used on larger search spaces in the future.
Anchoring and Adjustment Design: A User-Centered Design Strategy
Authors: Dixon Lisa A. , Colton Jonathan S.
Published: February 2021

“Anchoring and adjustment” and “deltaSpecs” are presented as concepts for modeling design scenarios in which “previous” re-design solutions form the basis for a new design. The “anchor” provides the basis for the redesign and may consist of a collection of previous design solutions (ideas, components, devices and solution principles). It represents the initial solution. The “deltaSpecs” represent the difference between the specifications for the “new” design and the current version of the design solution and guide the adjustment of the anchor toward the final solution. A case study on the design of the Scanning Tunneling Microscope (STM) illustrates the use of these concepts to describe a design development process strategy.
Configuration Design: An Integrated Approach Using Grammars
Authors: Schmidt Linda C. , Cagan Jonathan
Published: February 2021

A computational approach to design that integrates conceptual design, configuration design, and catalog component selection tasks overcomes some of the barriers to successful design automation. FFREADA is a design generation and optimization algorithm featuring hierarchical ordering of grammar based-design generation processes at different levels of abstraction. FFREADA is used to design hand-held, power drills and to develop an appropriate objective function for design optimization. The drill grammar expresses a vast space of design states that are not limited to any particular functional architecture or component configuration. (The algorithm’s optimization runs operate in a space which exceeds 20249 designs.) Good drill designs, those with values within 1% of the optimal solution, are found in minutes by sampling less than 0.15% of the design states. Optimal configurations are found for drills with three different torque requirements.
Numerating Possible Design Options for Integral Attachment
Authors: Genc Suat , Messler Robert W. , Gabriele Gary A. , Bonenberger Paul R.
Published: February 2021

Proliferation of plastic in parts, and the ability to mold such parts of great complexity at little cost penalty, has resulted in growing use of integral attachments (or so called snap-fits) in designs. The diversity of integral attachment features and the potential applications of this assembly method have made it appear that design possibilities may be unbounded. This paper extends an “attachment level” methodology first articulated by researchers at General Motors by enumerating all possible design options for 2-D (rectilinear) and 3-D (prismatic) polyhedral as well as 2-D and 3-D curvilinear parts using a recently developed hierarchical classification scheme. It was found that there are only 343 possible interface combinations that will allow attachment, of which only 150 are totally unique if one recognizes the interchangeability of attachment features between mating components comprising the assembly. Thus, for a seemingly infinite or unbounded group of possible real integral attachment applications, the choices are, in fact, limited to a quite manageable number. This allows designers to truly optimize a design by considering literally every possibility after working down through the classification hierarchy.
A Set-Based Approach to Stamping Designs
Authors: Lee Jinkoo , Ward Allen C. , Hu S. Jack
Published: February 2021

This paper describes a new approach to stamping designs in a concurrent engineering environment. The conventional stamping design approach is based on making iterative changes to a single design. In other words, a design has to be quickly guessed in order to proceed with the design process even if there are uncertainties in some design variables. There are two major drawbacks with this current approach: 1) one change in a part design can cause more changes to the designs for other interconnected parts; and 2) it is difficult to accomplish parallel development of stamping and tool designs, because a change to a stamping design may make obsolete the corresponding tool design. To improve ipon these drawbacks, we present a set-based approach to stamping designs in contrast to the conventional approach of making iterative changes to a single design. In this set-based approach, stamping and tool designers represent design possibilities for functional and manufacturing requirements. As the design process continues, the design possibilities are narrowed by removing impossible or infeasible designs with concrete data. As a real-world example, Toyota uses “design tolerances” for design possibilities and “lessons learned” books for manufacturable shapes that are identified through decades of experiences. This paper presents a computational tool developed to support the set-based approach, in which the computational tool contains three components: representation of sets of shapes, removal of infeasible regions, and selection of some feasible shapes for visual checking.
Forming Product Design Specifications
Authors: Otto Kevin N.
Published: February 2021

Design teams commonly form quantitative functional specification lists that define performance targets for a product. Meeting these specifications ensures that the customer needs are satisfied. A central difficulty is to identify the relevant metrics to use as specifications. A working methodology is presented here to establish relevant, quantitative, measurable performance specifications. To start, customer needs, their importances, and the customer use patterns are gathered for the product. Voice-of-the-customer methods are augmented to distinguish no-compromise constraints that must be met. Next, a design is analyzed to establish a representative function structure, applying Pahl and Beitz’s systematic design approach. An optimal function structure can now be defined by a condition of simultaneous maximum simplicity and comprehensive coverage of the gathered customer needs. The function structure can then be used as a list over which specifications are to be made, with at least one specification per sub-function. Having a rational function structure allows a team to more easily determine variables on which to make specifications. A team can then use the House of Quality to document and form consensus over these specifications in the typical way.
Student Responses to Impromptu Estimation Questions
Authors: Linder Benjamin , Flowers Woodie
Published: February 2021

Undergraduate students were asked to give rough estimates for basic engineering quantities associated with common engineering artifacts. Their responses to two such estimation questions are presented and discussed. Examples are drawn from the responses to illustrate the extreme difficulty students had performing estimates and using engineering fundamentals in impromptu situations. We propose a shift from engineering pedagogy’s focus on detailed analysis to a focus on estimation to improve students’ overall problem-solving skills.
A Reverse Engineering and Redesign Methodology for Product Evolution
Authors: Otto Kevin N. , Wood Kristin L.
Published: February 2021

New products drive business. To remain competitive, industry is continually searching for new methods to evolve their products. To address this need, we introduce a new reverse engineering and redesign methodology. Motivation is provided by the S-curve product improvement history. We start by formulating the customer needs, followed by reverse engineering, creating a functional model through teardowns. The functional model leads to specifications that match the customer needs. Depending upon required redesign scope, new features are possibly conceived, or not. Next models of the specifications are developed and optimized. The new product form is then built and further optimized using designed experiments. An electric wok redesign provides an illustration. The methodology has had a positive impact in results and systematic approach, both on design education and application.
Formalisms for Negotiation in Engineering Design
Authors: Scott Michael J. , Antonsson Erik K.
Published: February 2021

Engineering projects often undergo several design iterations before being completed. Information received from other groups working on a project (analysis, manufacturing, marketing, sales) will often necessitate changes in a design. The interaction between different groups associated with a design project often takes the form of informal “negotiation.” This form of interaction commonly arises when engineering information is imprecise. The Method of Imprecision (MOI) is a formal method for the representation and manipulation of preliminary and imprecise design information. It provides a mechanism for the formalization of these informal negotiations. The nature and scope of informal negotiation in engineering is explored and discussed, and application of the MOI is illustrated with an example.
On the Nature and Consequences of Functional Couplings in Axiomatic Machine Design
Authors: Johannesson Hans L.
Published: February 2021

A functional coupling is defined in this work as a harmful interaction between two sub-systems, components or parts on the same hierarchical level within a product structure. In order to qualify as a functional coupling this interaction must be such that the choice of one sub-system, component or part solution decreases the possibility to fulfil the requirements governing another solution. In this work the nature and characteristics of such functional couplings are analysed and the following consequences when judging the degree of functional coupling in a product are discussed.

In particular this work identifies and classifies the information needed to characterize and judge functional couplings in structural axiomatic machine design. The information needed for coupling removal decisions is identified. This is very important as it increases the robustness of a design. Furthermore, the difficulty with limited information on higher hirarchical product structure levels is discussed and an iterative strategy to deal with this problem is suggested.
Dependence of Early Engineering Concepts on Information Characteristics
Authors: Knoop Willem G. , van Breemen Ernest J. J. , Vergeest Joris S. M. , Wiegers Tjamme
Published: February 2021

The expectations of computer tools to support the conceptual design phase are not yet met. An experimental approach to discover the use of information in conceptual design will give a realistic insight of the information requirements. This can be used to specify future computer support systems. A method to observe the use of information in a conceptual design process has recently been developed. The method has been tested and fine-tuned through the observation of 10 design sessions. Valuable empirical data resides from this experiment. Data has been analyzed in several perspectives. This paper presents the results of the activity/information analysis of the experiment in relation with the quality of the design concept. For the latter a rating system has been defined to quantify this. We have found a significant positive correlation of the amount of information that is communicated and the quality of the design. Furthermore a discussion is given on the relation between information and the activities of the designer. Analysis activities are more communication intensive compared to synthesis and evaluation tasks.
Required and Requested Information During Conceptual Engineering Design As Found by Categorization of Empirical Data
Authors: Wiegers Tjamme , Van Breemen Ernest J. J. , Knoop Willem G. , Vergeest Joris S. M.
Published: February 2021

To offer effective computer support in the early stages of the engineering process, we need more insight in the information needs of the designer during these stages. For this reason we developed a new method to observe the information handling of a designer, without forcing him or her to think aloud. We applied this method in ten sessions in which a subject had to perform a design assignment. We compared the information actually requested by the subjects, with the set of information that would be generally required according to an independent expert designer. Individual subjects differed much in the engineering aspects about which they requested information. Only 10% of the engineering aspects was requested by seven or more of them. The number of requested aspects corresponds well with the extent to which their concepts meet the requirements. We present a detailed picture of these differences and discuss possible explanations. An independently measured variable in the experiment was the designer’s performance in terms of the requirements met by the resulting design objects. We found a significant positive effect of the amount of different requested engineering aspects on this performance. The interpretation of this finding and its implications will be discussed.
Enabling Concurrent Engineering Through Collaborative Product and Process Data Management
Authors: Chen Yuh-Min , Ho Cheng-Ter , Hsiao Yun-Tau
Published: February 2021

This paper presents a collaborative data management framework which is capable of supporting information sharing and team data management in concurrent team-oriented product and process development by providing functions for project configuration, personal product and process item management, and team library management. Establishing this framework involves: (i) identification of functional requirements for computer-aided engineering data management through the investigation of concurrent product delivery process, with an emphasis on product and process development, (ii) use of system engineering and object-oriented modeling techniques for development of the proposed framework.
Architectures of Concurrent Engineering System for Composites
Authors: Zhang Jian , Hahn H. Thomas
Published: February 2021

The demand for the better quality products with shorter lead-time and lower life-cycle cost forces the manufacturing enterprises all around the world to optimize their production strategies from both enterprise engineering and enterprise operation respectively. This paper addresses the architectural issue of applying the Concurrent Engineering (CE) approach in the composite manufacturing area. It first discussed briefly the characteristics of composite manufacturing process to examine the feasibility and possibility of applying the CE approach to improve its process productivity and product quality. Then the functional requirements for a concurrent engineering system for composites (CESC) were defined from both operational and architectural points of view. Finally, the integrated infrastructure based system architectures for the CESC were presented in accordance with the physical system requirements, and so were the associated and currently conducted R&D focuses for the system.
Optimizing Flexibility in a Sugar Packaging System
Authors: Levermore David M. , Derby Stephen
Published: February 2021

This paper investigates the optimization of flexibility in production systems. The problems associated with sugar production, at the Sugar Industry of Jamaica, is used as a case study. The lack of flexible packaging machinery is identified as a component of these problems. The paper proceeds to assemble a system capable of effectively accomplishing the packaging of bags of various sizes. A simulation of the system using petri nets is used to validate this project.
Modeling Issues for the Intelligent Simulation of Multibody Dynamics
Authors: Cuadrado Javier , Cardenal Jesús , Bayo Eduardo
Published: February 2021

Current simulation tools for multibody dynamics are not problem dependent, they use the same modeling process to all cases regardless of their characteristics. In addition, real-time simulation of small multibody systems is achievable by existing simulation tools, however, real-time simulation of large and complex systems is not possible with existing methods. This is a challenge that needs to be addressed before further advances in mechanical simulation with hardware-in-the-loop and man-in-the-loop, as well as virtual prototyping are made possible.

This paper addresses the issue of how the modeling process-dependent versus independent coordinates, and descriptor form versus state-space form of the equations of motion-affects the dynamic simulation of multibody systems and how it may be taken into account and added to the concept of intelligent simulation. With this new concept all the factors involved in the simulation process — modeling, equations, solution, etc. — are chosen and combined depending upon the characteristics of the system to be simulated. It is envisioned that this concept will lead to faster and more robust real-time simulators.
Geometrical Properties of the Generalized Inverse and its Application to the Inverse Velocity Analysis of Planar Redundant Manipulators
Authors: Martínez José María Rico , Davidson Joseph K.
Published: February 2021

The geometrical properties of the generalized inverse, a scheme frequently applied to the inverse velocity analysis of redundant manipulators, are presented. The columns of the Jacobian matrix, as well as, the rows of the generalized inverse are identified with infinitesimal screws. Then, many geometric properties of these screws are obtained and summarized, especially those that relate to the location of the row screws that appear in the generalized inverse. These properties are then used to develop a simplified alternative method for computing the generalized inverse of planar redundant manipulators.
Assur’s Groups, AKCs, Basic Trusses, SOCs, etc.: Modular Kinematics of Planar Linkages
Authors: Ceresole E. , Fanghella P. , Galletti C.
Published: February 2021

The paper presents a unified point of view on modular methods of kinematic analysis of planar linkages. It is shown that various approaches adopted in different fields, such as linkage analysis, robot kinematics, variational CAD systems, are based on the common idea of decoupling complex systems of equations by solving sequences of simpler subsystems. These subsystems correspond to modules with particular topological properties. Then, the three main issues of a modular method, namely, systematic topology of the modules, solution algorithms for each module, and module recognition in a given mechanism, are discussed and solutions are provided by means of the general unifying concept of Assur Kinematic Chain (AKC).
Finding All Solutions to Approximate Synthesis of Planar Linkages for Function Generation, Rigid-Body Guidance and Path Generation
Authors: Liu An-Xin , Yang Ting-Li
Published: February 2021

Generally, approximate kinematic synthesis of planar linkage is studied using optimization method. But this method has two defects: i) the initial guesses are hard to determine and ii) the global optimum solution is difficult to find. In this paper, a new method which can find all solutions to approximate kinematic synthesis of planar linkage is proposed. Firstly, we reduce the approximate synthesis problem to finding all solutions to polynomial equations. Polynomial continuation method is then used to find all solutions. Finally, all possible linkages can be obtained. Approximate syntheses of planar four-bar linkage for function generation, rigid-body guidance and path generation are studied in detail and 3 examples are given to illustrate the advantages of the proposed method.
Kinematic Geometry of Wheeled Vehicle Systems
Authors: Sreenivasan S. V. , Nanua P.
Published: February 2021

This paper addresses instantaneous motion characteristics of wheeled vehicles systems on even and uneven terrain. A thorough kinematic geometric approach which utilizes screw system theory is used to investigate vehicle-terrain combinations as spatial mechanisms that possess multiple closed kinematic chains. It is shown that if the vehicle-terrain combination satisfies certain geometric conditions, for instance when the vehicle operates on even terrain, the system becomes singular or non-Kutzbachian — it possesses finite range mobility that is different from the one obtained using Kutzbach criterion. An application of this geometric approach to the study of rate kinematics of various classes of wheeled vehicles is also included. This approach provides an integrated framework to study the kinematic effects of varying the vehicle and/or terrain geometric parameters from their nominal values. In addition, design enhancements of existing vehicles are suggested using this approach.

This kinematic study is closely related to the force distribution characteristics of wheeled vehicles which is the subject of the companion paper [SN96].
The Inverse Force Analysis of a Four-Bar Mechanism With Compliant Input and Output Links
Authors: Yin J. P. , Matthew G. K. , Duffy J.
Published: February 2021

A closed-form inverse force analysis was performed for a planar four-bar mechanism with a rigid coupler and frame but with compliance in the form of linear springs in the input and output links. A known force was applied to the coupler link on a line fixed in the plane containing the frame. A sixteenth degree polynomial in the tan-half-angle of the angular displacement of the output link was derived using algebraic elimination. A numerical result is presented which verifies the solutions.
A Coordinate Invariant Formulation of the Dynamics of Cooperating Robot Systems
Authors: Ploen Scott R. , Park Frank C.
Published: February 2021

In this article we formulate the dynamics of cooperating robot systems using standard ideas and notation from the theory of Lie groups. Beginning with the coordinate-invariant formulation of robot dynamics introduced in Ploen and Park (1995), we extend these results to develop the equations of motion of a system of N cooperating robots manipulating a common workpiece. In the resulting dynamic equations the mass matrix, Jacobian, Coriolis, and gravity terms of the closed chain system admit concise block-triangular factorizations in terms of simple linear operators on se(3), the Lie algebra of the Euclidean group SE(3). A straightforward manipulation of the equations of motion and the kinematic constraints leads to a closed-form expression for the forces of constraint in which the robot parameters appear in a transparent manner.
An Efficient Trajectory Planning Method for Binary Manipulators
Authors: Lees David S. , Chirikjian Gregory S.
Published: February 2021

Binary manipulators have actuators with only two stable states. Therefore, they can reach only a finite number of locations. Compared to a manipulator built with continuous actuators, a binary manipulator provides reasonable performance, robustness, and is relatively inexpensive (up to an order of magnitude cheaper). The number of states attainable by a binary manipulator grows exponentially with the number of actuators. This makes brute force calculation of the inverse kinematics impossible for binary manipulators with many actuators. This paper presents a combinatorial method for planning trajectories for a binary manipulator while reducing the search space to a manageable size. Despite the discrete nature of binary actuation, it also creates motions that follow a specified trajectory accurately (in both position and orientation) without large deviations of the end-effector from the specified path.
Experimental and Finite Element Modal Analyses of Planar Mechanisms With Three-Dimensional Geometries
Authors: Smaili Ahmad , Bagci Ismail
Published: February 2021

This article presents the results of numerical and experimental modal analyses of a planar four-bar (4R) mechanism having three dimensional geometry due to the offsets between its links. An experimental mechanism is built and modern modal testing techniques are used. A five-node isoparametric finite element is developed and used to model the mass and flexibility of the links and joints, link offsets, and drive and load shafts. The results obtained from the finite element solution matched closely the experimental results, a testimony to the accuracy of the proposed element. The results indicated that link offsets have considerable influence on the dynamic characteristics of a mechanism system and should be considered in dynamic modeling of planar mechanisms.
Two Precision Position Synthesis of Planar Linkages With Positional Rectification
Authors: Mirth John A.
Published: February 2021

Precision position synthesis is used to generate planar linkages that pass through two exact positions and an additional number of approximate positions. The approximate positions provide a means of rectifying the solution linkages such that all solutions presented are more likely to describe a motion that remains within acceptable positional bounds. The rectification method involves the development of three different numerical algorithms that may be applied to a particular step in the dyad/triad method of precision position synthesis. The three algorithms presented can be applied in a variety of combinations to allow for the synthesis of both simple (four-bar) and complex (multiloop) planar linkages.
Nonlinear Dynamics and Vibrations of Three Dimensional Multibody Tracked Vehicles
Authors: Shabana A. A. , Choi J. H. , Lee H. C.
Published: February 2021

A three dimensional model that includes significant details is developed for the nonlinear dynamic analysis of large scale multi-body tracked vehicle systems. In this model, the joint articulations of the track chains are taken into consideration so as to allow the developement of a computational procedure for the analysis of the vibrations and the contact forces of the multibody tracked vehicles. The three dimensional vehicle system is assumed to consist of three kinematically decoupled subsystems which include the chassis subsystem, and two track subsystems. A recursive approach for formulating the nonlinear equations of the vehicle based on the velocity transformation is used in this investigation in order to reduce the number of equations, avoid the solution of a system of differential and algebraic equations, and avoid the use of nonholonomic constraints to describe the rotations of the sprockets. The singular configurations of the closed kinematic chains of the tracks are also avoided by using a penalty function approach to define the constraint forces at selected secondary joints of the tracks. Detailed three dimensional nonlinear contact force models that describe the interaction between the track links and the vehicle components such as the rollers, sprockets, and idlers as well as the interaction between the track links and the ground are developed and used to define the generalized contact forces associated with the vehicle generalized coordinates. In particular, body and surface coordinate systems are introduced in order to define the spatial contact conditions that describe the dynamic interaction between the teeth of the sprockets and the track link pins. These conditions provide the forces necessary for driving the tracked vehicle. The effect of the tangential friction forces on the stability of the motion of the vehicle is also discussed in this investigation. A computer simulation of a tracked vehicle that consists of one hundred and six bodies and has one hundred and twenty degrees of freedom is presented in order to demonstrate the use of the formulations presented in this study. A simple formula that can be used to predict the steady state velocity of the vehicle when the sprockets rotate with a constant angular velocity is presented and used to verify the numerical results obtained from the nonlinear dynamic simulation of the multibody vehicle.
Dynamic Analysis of Flexible Mechanisms With Clearances
Authors: Wang Yu (Michael) , Wang Zaiping
Published: February 2021

A finite element method in time is presented for the periodic solution of vibrating elastic mechanisms with clearances. The solution of motion is made possible by utilizing time finite elements which discretize the forcing time period into a number of time intervals. During each interval, the solution form is derived from a Hamilton’s law of varying action. The periodic response is described in terms of a set of temporal nodes of all spatial degrees of freedom of the system, yielding a block-diagonal nonlinear algebraic system to be solved iteratively. The suggested method is applied to an example problem of cam-driven valve train, demonstrating the effectiveness of the method in dealing with multiple clearance nonlinearities.
Numerical Formulations for Computing Design Propagations of the Spatial Slider-Crank Mechanism
Authors: Zou Hong-Liu , Abdel-Malek Karim , Wang Jia-Yi
Published: February 2021

A numerical formulation for studying the design of a spatial slider-crank mechanism is developed and illustrated. The mechanism is modeled using graph theory and closed loops are converted to a spanning tree structure by cutting joints and introducing new constraints. Variations of these constraints with respect to design parameters are derived. A change in link length or link orientation is propagated through the model and a new assembled configuration is computed hence redesigning the mechanism. Constraints are formulated in Cartesian space but computed in relative joint coordinate space. The Jacobian of the constraint is transformed to joint coordinate space in order to compute an assembled configuration for the cut-joint constraint formulation. The experimental code is illustrated through numerical examples where joint-position vectors and orientation matrices are altered.
On Steady-State Response of Multi-Cylinder Engine System
Authors: Shanshal Yassir , Farhang Kambiz
Published: February 2021

This paper deals with the rigid-body dynamic response of an internal combustion engine. An earlier work (Farhang and Midha, 1989) has presented an efficient algorithm for computing the steady-state rigid-body dynamic response of single degree of freedom engine systems. The method is utilized in the present work to examine the effects of spark time and combustion duration on the performance of a four-stroke, four-cylinder engine. In contrast with the earlier work in which combustion is viewed as an instantaneous process, in this work the combustion is accounted for and is related to the reference crank angle.
Robomech-III: A Stack of Three Four-Bar Chains for Triple-Function Task Applications
Authors: Smaili Ahmad , Rick Oliver
Published: February 2021

This paper presents Robomech-III, the third of a new class of linkage arms called robomechs. A robomech is a parallel architecture arm that combines features of a mechanism and a robot devised to perform coordinated multi-function tasks. In particular, Robomech-III is formed from a stack of three planar four-bar (4R) chain. This robomech requires three independently actuated joints to perform a specific triple-function task. The features of Robomech-III are discussed, a synthesis procedure is outlined and an application example is given.
A Framework for Closed-Form Displacement Analysis of Planar Mechanisms
Authors: Almadi Abdulaziz N. , Dhingra Anoop K. , Kohli Dilip
Published: February 2021

This paper presents a closed-form approach, based on theory of resultants, to the displacement analysis problem for n-link planar mechanisms. The proposed approach, called the method of successive elimination, generalizes Sylvester’s dialitic eliminant to the case when m equations (m ≥ 3) are to be solved in m unknowns. Conditions under which the method of successive elimination can be used to reduce m equations (in m unknowns) into a univariate polynomial, devoid of spurious roots, are presented. This univariate polynomial corresponds to the 1/0 polynomial of the mechanism. A comprehensive treatment is also presented on some of the problems associated with the conversion of transcendental loop-closure equations into an algebraic form using tangent-half-angle substitutions. It is shown how trigonometric manipulations in conjunction with tangent-half-angle substitutions can lead to extraneous roots in the solution process. Theoretical conditions for identifying and eliminating these spurious roots are presented. The computational procedure is illustrated through the displacement analysis of a 10-link SDOF mechanism which has 4 independent loops.