bluuebunny/crossref_metadata_2025 huggingface dataset:
Trust Region Augmented Lagrangian Methods With Secant Hessian Updating Applied to Structural Optimization
Authors: Coster J. E. , Stander N. , Snyman J. A.
Published: February 2021

The problem of determining the optimal sizing design of truss structures is considered. An augmented Lagrangian optimization algorithm which uses a quadratic penalty term is formulated. The implementation uses a first-order Lagrange multiplier update and a strategy for progressively increasing the accuracy with which the bound constrained minimizations are performed. The allowed constraint violation is also progressively decreased but at a slower rate so as to prevent ill-conditioning due to large penalty values. Individual constraint penalties are used and only the penalties of the worst violated constraints are increased. The scheme is globally convergent. The bound constrained minimizations are performed using the SBMIN algorithm where a sophisticated trust-region strategy is employed. The Hessian of the augmented Lagrangian function is approximated using partitioned secant updating. Each function contributing to the Lagrangian is individually approximated by a secant update and the augmented Lagrangian Hessian is formed by appropriate accumulation. The performance of the algorithm is evaluated for a number of different secant updates on standard explicit and truss sizing optimization problems. The results show the formulation to be superior to other implementations of augmented Lagrangian methods reported in the literature and that, under certain conditions, the method approaches the performance of the state-of-the-art SQP and SAM methods. Of the secant updates, the symmetric rank one update is superior to the other updates including the BFGS scheme. It is suggested that the individual function, secant updating employed may be usefully applied in contexts where structural analysis and optimization are performed simultaneously, as in the simultaneous analysis and design method. In such cases the functions are partially separable and the associated Hessians are of low rank.
A Systems Approach to Structural Topology Optimization: Designing Optimal Connections
Authors: Jiang Tao , Chirehdast Mehran
Published: February 2021

In this paper, structural topology optimization is extended to systems design. Locations and patterns of connections in a structural system that consists of multiple components strongly affect its performance. Topology of connections is defined, and a new classification for structural optimization is introduced that includes the topology optimization problem for connections. A mathematical programming problem is formulated that addresses this design problem. A convex approximation method using analytical gradients is used to solve the optimization problem. This solution method is readily applicable to large-scale problems. The design problem presented and solved here has a wide range of applications in all areas of structural design. The examples provided here are for spot-weld and adhesive bond joints. Numerous other potential applications are suggested.
The Application of a Concurrent Design Optimization Tool to a Composite Panel for a Naval Ship Structure
Authors: Dirlik S. , Hambric S. , Azarm S. , Marquardt M. , Hellman A. , Bartlett S. , Castelli V.
Published: February 2021

A prototype concurrent design optimization tool, named CELS for Concurrent Engineering of Layered Structures, has been developed. This tool can be used to analyze and/or optimize the conceptual design of a composite panel for Naval ship topside structures. CELS integrates five technology modules: (1) electromagnetic interference, (2) radar cross section, (3) structures, (4) cost, and (5) weight. Two optimization methods drive the integration of the technology modules. These methods include: (i) a local optimizer based on feasible sequential quadratic programming, and (ii) a global optimizer based on an exhaustive search. To obtain an objectively balanced design, “goodness” measures are allocated for each objective or constraint function. These measures, via a graphical user interface, allow topside designers to easily and quickly assess the impact of their decisions on various technologies. The utility and capability of CELS are demonstrated via the design of a topside composite panel. The design study shows that CELS can be easily adapted to different topside conceptual design problems, and that design tradeoffs can be performed quickly and used in decision making.
Mixed Continuous Variable and Catalog Search Using Genetic Algorithms
Authors: Senin Nicola , Wallace David R. , Jakiela Mark J.
Published: February 2021

In this paper a general design and catalog representation is proposed and implemented. The representation is applied to mixed continuous variable and catalog search using genetic algorithms. The representation addresses a number of common catalog search design scenarios. In addition to catalogs of static data (e.g., different sizes of pipes), it is possible to model/search subdesigns that can provide performance data based upon operating conditions. The use of catalog hierarchies allows the search to simultaneously consider catalogs from different vendors and at different levels of detail, therefore achieving the capability of modeling solutions containing general information. The capabilities of the representation are demonstrated through an object-oriented computer implementation that uses a genetic optimization and search algorithm.
Modeling of Ram Extrusion Process and Optimal Die Design
Authors: Deng Qingwen , Lin Yuyi
Published: February 2021

This paper presents a one-dimensional analytical model of the ram extrusion process of a powdered material and a procedure for optimizing the shape of the extrusion die. Powdered coal mixed with water and asphalt was used as the extrudate material in the model development. The analytical model relates the pressure at the entrance of the die to the exit pressure of the die. Certain key parameters of the model were obtained from experiments. The comparison of the inlet pressure derived from the analytical model and the value obtained from the experimental procedure shown a good agreement. Optimization algorithms were applied to generate the ideal die shape. The objective is to minimize the power consumed in the extrusion process, while maintaining maximum strength for the extrudates. It is concluded from the study that the model and the optimization procedure developed for the model can be used in extrusion studies of other powdered materials.
Stepper Motor Driven Four-Bar: Dynamic Modeling and Synthesis
Authors: Wang Sern-Hong , Pisano Albert P.
Published: February 2021

This paper presents the dynamic modeling and synthesis of a four-bar mechanism that is driven by a four-phase, variable-reluctance stepper motor. Dynamic models of both the mechanism and the motor are derived and subsequently combined in order to numerically determine the system dynamic response. In the stepper motor model, full circuit equations are derived for each of 8 stator poles, with full expressions for armature self- and mutual-inductances, as well as developed motor torque. The stepper motor model admits arbitrary input pulse trains, and includes both coil resistance and inductance. A set of five, simultaneous, nonlinear, second-order ordinary differential equations is analytically derived and numerically solved to determine stepper response. In the four-bar mechanism model, three dynamical properties (primary effective inertia, secondary effective inertia, and gravitational disturbance torque) are derived using a Lagrangian approach, and utilized to determine the dynamic suitability of candidate four-bars for three-position, rigid body guidance. Three candidate four-bar mechanisms are synthesized, and their dynamic response (when coupled to the variable-reluctance stepper motor) is compared. It is shown that an engineering trade-off exists between parallelogram and crank-rocker four-bars, in which the former may possess lower primary effective inertia, but the latter may possess lower gravitational disturbance torque.
A Virtual Corporation: An Interdisciplinary and Collaborative Undergraduate Design Experience
Authors: Howell Steve , Harrington Tim , Larson Debra , Collier Ken , Hatfield Jerry
Published: February 2021

Engineering industries are calling for graduates that have a breadth of skills including design and analysis skills, teaming skills and “soft skills” (i.e., project management, concept value analysis, communication, cross-disciplinary understanding, etc.) Furthermore, many American industries are implementing “virtual project work teams”, where expert teams work concurrently in several remote locations, sharing design information and data electronically.

Northern Arizona University’s College of Engineering and Technology is implementing an innovative, four-year, sequence of classes called the Path to Synthesis. The sophomore and junior courses in the Path to Synthesis program are team-taught industry simulations which use collaborative product design to not only develop design skills, teamwork skills, and soft engineering skills, but to also encourage the use of state of the art design methods and professional software tools. During the Fall 1995 semester, a “virtual team” paradigm was introduced into these two classes. NAU students worked with “expert” teams at other institutions to collaboratively complete a major design project. Students used modern high speed electronic media to communicate design ideas, share electronic data, and complete a project which required expertise from student teams dispersed across a wide geographic area.

This paper describes the piloted junior and sophomore level Path to Synthesis courses, and how geographically distributed teams located in Flagstaff, Tempe, and San Francisco collaborated on different aspects of an industrial simulation. This collaborative effort required the use of modern high speed electronic networks for communication, live two way video interaction, and transfer of graphic and CAD data.
Design of Mobile Temperature Monitor System for Autobrazer Baseline Calibration
Authors: Agba Emmanuel I. , Jones E. William , Penaherrera A. Simon , Thrift Bruce
Published: February 2021

The production of heat exchanger coils involves the brazing of return tubes and hairpins to complete the refrigeration circuit. The knowledge of the temperature distribution within an autobrazer is essential for the control of process variables such as burner alignment, gas/flux mixture and conveyor speed. This paper presents the design of a mobile temperature monitor system to measure temperature distributions for the proces s control of an autobrazer. The physical characteristics of the monitoring system in the area of temperature transducer locations simulate closely the actual characteristics of the brazing process. By comparing a measured temperature distribution with a known optimal distribution, the process variables can be adjusted either manually or automatically to affect the process for maximum brazing efficiency. Presently, process variables are adjusted manually and often these adjustments are not repeatable, resulting in high percentage of production coil rejects and subsequent rework.
Design Reasoning Using Plastic Injection Molding Primary Features
Authors: Wood Stephen L.
Published: February 2021

The conceptual design of industrial components requires the engineer to be knowledgeable and competent in designing with features. Basic design features are the primary building blocks of designers: mechanical engineers, industrial engineers, material processing engineers, and tooling specialists. Each feature is specifically used to satisfy an intended function by the individual designer. How the features are used is based upon the experience of the designer and the potential of various features to satisfy specific functions.

This paper develops the primary features used by designers in the injection plastic molding domain, according to their functional properties. The analysis of a part’s functions satisfied by various features, along with the frequency of use, gives an overview of the most pertinent aspects of feature based design. The next generation CAD systems should incorporate design reasoning as a part of the design process algorithms and the capacity to analyze the functional aspects of each feature.
What Are Feature Interactions?
Authors: Regli William C. , Pratt Michael J.
Published: February 2021

Manufacturing features and their interactions have become areas of research scrutiny in recent years. It is widely accepted that intelligent reasoning about interactions among features is a critical element in the development of systems for automated manufacturing. Conversely, however, there has not emerged any general consensus as to what features are, how they are defined, and what it means when one says that features interact.

This paper attempts to focus and refine what is meant by the term feature interaction and outline precisely how interactions can affect automated feature recognition and manufacturing planning. It is our belief that, by establishing a conceptual common ground with regard to these concepts, the research community will be better able to assess how to effectively address the problems that they present.
Reconfigurable Feature Recognition for an Adaptable, Maintainable CAD/CAPP Integration
Authors: Gaines Daniel M. , Castaño Fernando , Hayes Caroline C.
Published: February 2021

This paper presents MEDIATOR, a feature recognition system which is designed to be maintainable and extensible to families of related manufacturing processes. A problem in many feature recognition systems is that they are difficult to maintain. One of the reasons may be because they depend on use of a library of feature-types which are difficult to update when the manufacturing processes change due to changes in the manufacturing equipment. The approach taken by MEDIATOR is based on the idea that the properties of the manufacturing equipment are what enable manufacturable shapes to be produced in a part. MEDIATOR’S method for identifying features uses a description of the manufacturing equipment to simultaneously identify manufacturable volumes (i.e. features) and methods for manufacturing those volumes. Maintenance of the system is simplified because only the description of the equipment needs to be updated in order to update the features identified by the system.
Part to Art
Authors: Sinha Sarvajit S. , Seneviratne Pradeep
Published: February 2021

We posit that free-form design of 3D shapes is far easier when done with a physical medium such as clay than on a 2D computer screen. To this end, we have built a Computer Aided Reverse Engineering system called Surfacer which allows conversion of three-dimensional measurements of the physical prototype into NURBS surfaces that can be manipulated by most Computer Aided Design and Manufacturing systems. The system’s interface has been made simple enough to be mastered by anyone, and the software provides a number of mathematical algorithms that simplify the task of converting 3D data into surfaces. This software and its algorithms are the focus of this paper.
Computing Boolean Combinations of Solids Composed of Free-Form Surfaces
Authors: Krishnan Shankar , Manocha Dinesh
Published: February 2021

We present efficient and accurate algorithms for Boolean combinations of solids composed of sculptured models. The surface of each solid is represented as a collection of trimmed and untrimmed spline surfaces and a connectivity graph. Based on algorithms for trapezoidation of polygons, partitioning of polygons using polygonal chains, surface intersection of high degree spline surfaces and ray-shooting, the boundaries of the resulting solids and its connectivity graph after the Boolean operation are computed. The algorithm has been implemented and its performance measured on a number of industrial models.
Kinematics-Based Geometric Design of Sculptured Surfaces
Authors: Ge Q. J. , Kang Donglai
Published: February 2021

Current practice in CAD/CAM separates the process of geometric shape design from that of CMC (Computer Numerically Controlled) tool path generation. Although successful for 3-axis machining, this strategy is not as effective for 5-axis machining of sculptured surfaces due to the difficulty in generating accurate and gouge-free 5-axis tool paths from the CAD models. This paper presents a framework for a new, kinematics-based methodology for geometric modeling that integrates sculptured-surface design with too-path generation for 5-axis CMC machining. In particular, sculptured surfaces are represented directly in terms of rational Bézier and B-spline motions of the cutting tool. The proposed framework brings together the fields of Kinematics and Computer Aided Geometric Design as well as the recent results in Computer Aided Motion Synthesis and Swept Volume Modeling and provides a basis for concurrent geometric shape design and manufacture.
Machining Algebra for Mapping Volumes to Machining Operations
Authors: Shirur Arvind , Shah Jami J.
Published: February 2021

This paper presents geometric models for representing machining operations. The characteristic shapes produced by machining operations are represented in a uniform (canonical) way for all machining operations as the resultant to two types of tool-workpiece interactions. Each interaction is characterized by a type of sweep operator. The directors of these sweep operations are derived from cutting and feed motion directions. The profiles used in the sweeps are defined in terms of geometric entities and constraints based on tool geometry and tool-workpiece interaction. Most conventional machining processes can be represented using the proposed model (process-to-volume mapping). Inverse operators are also defined for mapping volumes to processes; the inverse operators can be used in selecting potential machining processes for removing given volumes. Thus, representation of machining knowledge is process-based not feature-based, which overcomes the problem of dealing with new feature shapes that are not predefined in the process selector.
Design by Word and Deed
Authors: Fukuda Shuichi
Published: February 2021

It is becoming more and more important to consider how we should integrate our knowledge of skills into design, if we really wish to integrate design and manufacturing, because skills play very important roles in manufacturing. Although there are many design systems avaible, most of them deal only with the symbolic representation of our knowledge and even such medias as TV, video, etc which are considered to be good for skill representation are still in most cases one way from a teacher to a student. To really learn a skill, feedback from a student to a teacher should be established and more interactiveness secured.

We developed a prototype system with the simple example of learning the skill of penmanship for the purpose of clarifying the problems of skill representation and with the hope of integrating skill knowledge into design in the future.
Kitchen Layout Design in Virtual Environments
Authors: Yamamura Akira , Hatanaka Tomoyuki , Nomura Junji
Published: February 2021

This report is a description of our Virtual Reality (VR) technology application, a VR-supported kitchen layout design system. This VR system was developed on personal computers and has made it possible to achieve hardware cost reduction and a user-friendly interface. With the VR system, customers can have a pseudo-experience of their “virtual kitchen” and modify the design of the kitchen. This system helps our customers to make decisions when designing the layout of their new kitchen by giving them a good idea of their potential purchase. The VR system has been in practical use in Matsushita’s showrooms since 1994. In the future, we plan to put the VR system on the Internet. The VR system will also play an important role in user interface in the House Design Advisory System. This system, which we are currently developing, will give advice on house design, as well as on kitchen layout design, according to the customers’ diversified lifestyles.
An Integrated Product and Process Data Model Using Step
Authors: Ghodous Parisa , Vandorpe Denis
Published: February 2021

The integration in computer integrated manufacturing systems (CIMs) plays a significant role in improving the quality and productivity. To achieve this objective, a uniform product and process representation and an effective, comprehensive and reliable data exchange mechanism are required. Recent works on product data integration have led to STEP (international Standard for Exchange of Product data models). In this paper, we define a model which integrates the STEP product data models with process data models. The idea of classification of STEP product data models is used to classify the process data models. Examples from mechanical industries are included to demonstrate the features of this model.
The Green Browser: An Information Sharing Tool for Product Life Cycle Design
Authors: Kurakawa Kei , Kiriyama Takashi , Baba Yasunori , Kobayashi Hideki , Umeda Yasushi , Tomiyama Tetsuo
Published: February 2021

This paper presents the concept and implementation of the Green Browser, which enables designers and consumers to share environmental information. We propose the conceptual scheme of the Green Browser called green life cycle model. This model is intended to represent the product’s environmental impacts over the stages of raw materials, use, recycling, and disposal. The Green Browser has been implemented using WWW and MOO to be able to deal with the strategy model, which is the key element of the green life cycle model. A case study on building the strategy model of refrigerator is presented to illustrate the strategy model.
Quantified Relations: A Class of Predicate Logic Design Constraints Among Sets of Manufacturing, Operating, and Other Variations
Authors: Finch William W. , Ward Allen C.
Published: February 2021

This paper addresses a class of engineering design problems in which multiple sources of variations affect a product’s design, manufacture, and performance. Examples of these sources include uncertainty in nominal dimensions, variations in manufacture, changing environmental or operating conditions, and operator adjustments. Quantified relations (QR’s) are defined as a class of predicate logic expressions representing constraints between sets of design variations. Within QR’s, each variable’s quantifier and the order of quantification express a physical system’s causal relationships. This paper also presents an algorithm which propagates intervals through QR’s involving continuous, monotonic equations. Causal relationships between variables in engineering systems are discussed, and a tabular representation for them is presented. This work aims to broaden the application of automated constraint satisfaction algorithms, shortening design cycles for this class of problem by reducing modeling, and possibly computing effort. It seems to subsume Ward’s prior work on the Label Interval Calculus, extending the approach to a wider range of engineering design problems.
Conceptual Product Development
Authors: Ahrens Gritt , Tegel Oliver
Published: February 2021

The importance of conceptual modelling more and more becomes recognized in the industrial practice, since it is commonly known that it is during that phase of the product development process where fundamental choices are made that have a strong influence on the result of the development — the process!

The process of product development can only be efficient if it is basically put into practice methodically. The time additionally invested in the first steps of the methodical process of product development as it is described in the German guideline VDI 2221 prevents from forgetting important specifications or even overseeing possible ways of solution. This way the phase of conceptual modelling can result in a saving of time needed for product development due to fewer iteration loops for the correction of mistakes in later phases of the process and an increase of the product quality, too.

The prerequisite of the efficiency of conceptual modelling is a definition of the product specifications which is as precise as necessary and as abstract as possible in order not to restrict the amount of solutions in an unnecessary way.

Looking at the functions a product to be developed has to fulfill, the requirements list serves as a basis for the definition of function structures in which all functions and the relationships amongst each other are defined. This function structure can be utilized not only for the description of the product in an abstract way, but also for structuring the development process as well. With the definition of interfaces between parts of the product, implicitly interface specifications for the work on different parts of the product are defined. The function structure, therefore, can be used as a tool for management in the product development process.

Because of this, the information summarised in these documents must be available throughout the entire development process the information technological support of these tools should be standard. Nevertheless, common CAD-Software does not support any step of conceptual modelling. In this paper an information technological support for conceptual modelling is also presented. Furthermore, it is shown what kind of changes in and extensions of common CAX-Systems would be necessary for the realisation of this theory.
Total Value Management: A New Trend Beyond Total Quality Management (TQM)
Authors: Prasad Biren
Published: February 2021

One of the pitfall of total quality management (TQM) is that it is based on a single measurement, which has mostly been “quality” or “quality-driven.” Today manufacturing sectors are much more fiercely competitive and global than ever before. Consumers are more demanding, competition is more global, fierce and ruthless, and technology is advancing (and changing) rapidly. The quality-based philosophy inherent in TQM does not account for the shrinking time factor inherent in today’s complex product design, development and delivery (PD3) process. The competitors are always finding better and faster ways of doing things. Catching up in quality is not enough to be a world-class leader in manufacturing. It only makes a company at par with its competitors in terms of inheriting some of their product’s quality characteristics. But relatively speaking it gets you there only after a few years later. What is required is a total control of one’s own process — that is to identify and satisfy the needs and expectations of consumers better than the competitions and to do so profitably faster than any other competitor.

Competition has driven organization to consider concepts such as time compression (fast-to-market), concurrent engineering, design for X-ability, and tools and technology (such as Taguchi, Value Engineering, QFD, etc.) while designing and developing an artifact. Quality — as in TQM — addresses aspects of “quality” with reference to the functions a product has to perform. But, this is one of the many value characteristics that need to be considered by a world-class manufacturer. With conventional TQM process, it is difficult to address all aspects of Total Values Management (TVM) such as X-ability, cost, tools and technology, responsiveness and organization issues. It is not enough to include “Quality” into a product or process and expect the outcome to be a world-class. TVM efforts are vital in maintaining a competitive edge in today’s global marketplace. The question is how to address all value aspects of this TVM? This is what discussed in this paper. A new concurrent PD3 process for TVM methodology is proposed, which accounts for concurrency — paralleling of value characteristics — along with a methodology for their systematic deployments.
A Comparison of Equality Constraint Formulations for Concurrent Design Optimization
Authors: Tappeta Ravindra V. , Renaud John E.
Published: February 2021

This paper investigates a concurrent approach for design optimization. The method of Simultaneous ANalysis and Design (SAND) is tested in application to three Multidisciplinary Design Optimization (MDO) test problems. A Generalized Reduced Gradient (GRG) optimizer and a Sequential Quadratic Programming (SQP) optimizer are compared with respect to their efficacy in handling three different forms of equality constraints referred to as compatibility constraints in the SAND based optimization procedure. Results highlight the need for both strategies in application of SAND based design to different engineering test problems. More importantly significant savings in the number of analyses required for design optimization are observed when using the SAND approach of concurrent design. SAND based design delivers on the promise of concurrent engineering, namely to develop optimal designs, working concurrently, while reducing design cycle time.
A Finite Element Model for Hydroforming Parts With Rigid Tolerances
Authors: An Jian , Soni A. H.
Published: February 2021

For many key process parameters in such a hydroforming hole piercing operation, the fluid pressure and the piercing force might be the most important process parameters that determine a quality of hydroformed parts. However, designing such process parameters is still arrived at based on extensive trial-and-error activities and experiences. This situation prevents the hydroforming technology from being adopted further even though the benefits of using hydroforming as an alternative to the conventional stamping is obvious. In this study a finite element based simulation model is developed to investigate the effects of process parameters in a tubular part hydroforming process. The process parameters includes fluid pressure path and axial force path and the curvature of die profile. A simulation model developed for the study is based on an explicit nonlinear finite element code and includes three dimensional modeling of die, blank tube and hole piercing punch. The behaviors of the fluid pressure, axial force and die profiles on the deformation of a complex tubular part are predicted and the design of such process variables is achieved.
Kinematic Analysis and Singularity Loci of Spatial Four-Degree-of-Freedom Parallel Manipulators
Authors: Wang Jiegao , Gosselin Clément M.
Published: February 2021

The kinematic analysis and the determination of the singularity loci of spatial four-degree-of-freeedom parallel manipulators with prismatic or revolute actuators are discussed in this article. After introducing the architecture of the spatial parallel four-degree-of-freedom manipulators, algorithms for the solution of the inverse kinematic problem are provided for the two kinds of manipulators considered. Two different methods are presented for the derivation of the velocity equations and the corresponding Jacobian matrices are derived. The numerical determination of the workspace boundaries is then briefly discussed. Finally, the determination of the singularity loci is performed using the velocity equations and examples are given to illustrate the results obtained. Spatial four-degree-of-freedom parallel manipulators can be used in several robotic applications as well as in flight simulators. The determination of their singularity loci is a very important design issue.
Alternative Inverse Kinematic Equations for General RRP and RRR Regional Structures of Manipulators
Authors: Riley Peregrine E. J.
Published: February 2021

Many manipulators with six degrees of freedom are constructed with two distinct sections, a regional structure for spatial positioning, and an orientational structure having a common intersection point for the joint axes. With this arrangement, inverse kinematic solutions for position and orientation may be found separately. While solutions for general three link manipulators have been available since the work of Pieper in 1969, this paper presents new forms of the inverse kinematic equations for general RRP and RRR regional structures. Cartesian coordinates of the F-surface (generated by movement of the outer two joints) together with the outer joint angle are used as the equation variables. In addition, a second degree polynomial approxiamation of the equation may be used for quick iteration to a solution. It is hoped that these new equations will be useful by themselves and in workspace regions where solutions using equations in terms of the joint variables are numerically inaccurate or impossible.
Real-Time Computation of the Actual Posture of the General Geometry 6-6 Fully-Parallel Mechanism Using Two Extra Rotary Sensors
Authors: Parenti-Castelli V. , Di-Gregorio R.
Published: February 2021

The paper presents three algorithms for the determination of the actual configuration of the general geometry 6-6 fully-parallel mechanism by using two extra rotary sensors in addition to the six ones that are normally implemented in the servosystems of the six actuated legs. The three proposed algorithms provide a one-to-one correspondence between the sensor measurements and the configuration of the mechanism. Comparison of the three algorithms, that are all for real-time computation, is presented and one of them is shown to be a good compromise between precision and computation time.
A Workspace Analysis of RRP Manipulators
Authors: Ceccarelli Marco
Published: February 2021

An Analytical procedure is proposed for determining the workspace boundary of general telescopic RRP manipulators. The algorithm has been developed by using the Theory of Envelopes providing an algebraic formulation. An analysis of the workspace of RRP chain has been carried out to enlighten a general topology and to investigate the effect of link parameters and telescopic stroke.
Acceleration Analysis of Platform-Type Manipulators
Authors: Mohamed Maher G.
Published: February 2021

The screw algebra is used to efficiently derive expressions in compact form for both the angular accelerations of the moving links and the linear accelerations of points on the links of platform-type manipulators. The analysis employs the property that the acceleration state of the manipulator platform can be determined by considering the acceleration states of the links of only one — any one — of the manipulator legs. The obtained expressions provide an ease in symbolic and algebraic manipulation. The analysis is then extended to specify the acceleration center point of ithe nstantaneous motion of the manipulator platform. The acceleration center point is then used in expressing the distribution of the acceleration field of the platform instant motion which is important in manipulator synthesis. The special case of planar manipulators is studied and simpler expressions are derived. Numerical examples are presented for the analysis of a 3-DOF planar platform-type and of a 6-DOF spatial “Stewart Platform” manipulators to illustrate the analysis procedure.
Maximum Entropy Method for Optimal Linkage Function Generation
Authors: Hu Xinsheng , Zhou Ji , Yu Jun , Shi Baochang , Zong Zhijian
Published: February 2021

A new algorithm for solving optimal linkage function generation is proposed. The algorithm is simple in form, easily used and has much reliability and accuracy than any other algorithms reported on linkage synthesis. The existing standard software of unconstrained differential optimization can directly be used in it. Numerical experiments indicate the effectiveness of the new algorithm.
The Detection of Embedded Structure in Planetary Gear Trains
Authors: Hsu Cheng-Ho , Hsu Jin-Juh , Wu Yi-Chang
Published: February 2021

The detection of embedded structure is one of important steps in the structural synthesis of planetary gear trains. The purpose of this paper is to develop a computer program for the automatic detection of embedded structure in planetary gear trains. First, the graph representation of planetary gear trains are used to clarify the kinematic structure. Next, a method which is based on the concept of fundamental circuits for the detection of embedded structure in a planetary gear train. Using the notation of adjacency matrix, an interactive computer program has been developed such that embedded structure in a planetary gear train can be automatically analyzed by only entering the corresponding graph.
Camera Positioning Mechanism for ARIES: An Autonomous Mobile Robot
Authors: Rocheleau David N. , Moore Matthew M.
Published: February 2021

ARIES (Autonomous Robotic Inspection Experimental System) is under development for the Department of Energy (DOE) to survey and inspect drums containing low-level radioactive waste stored in warehouses at DOE facilities. This paper focuses on the development of CPS-II, the second generation camera positioning system used in the project. The first generation camera positioning system (CPS-I) positioned four identical but separate camera packages. CPS-II positions a single camera package which consists of vision cameras and other required sensors such as a bar-code reader and light stripe projectors. CPS-II is attached to the top of a mobile robot and consists of two mechanisms. The first is a lift mechanism composed of 6 interlocking rail-elements which starts from a retracted position and extends up and down to position the camera package to survey a column of drums four high. The second is a parallelogram special case Grashof four-bar mechanism which is used to deploy the camera package off the back of the robot. Both mechanisms are the subject of this paper.
Discretely Actuated Manipulator Workspace Generation by Closed-Form Convolution
Authors: Ebert-Uphoff Imme , Chirikjian Gregory S.
Published: February 2021

We discuss the determination of workspaces of discretely actuated manipulators using convolution of real-valued functions on the Special Euclidean Group. Each workspace is described in terms of a density function that provides for any unit taskspace volume of the workspace the number of reachable frames therein. A manipulator consisting of n discrete actuators each with K states can reach Kn frames in space. Given this exponential growth, brute force representation of discrete manipulator workspaces is not feasible in the highly actuated case. However, if the manipulator is of macroscopically-serial architecture, the workspace can be generated by the following procedure: (1) partition the manipulator into segments; (2) approximate the workspace of each segment as a continuous density function on a compact subset of the Special Euclidean Group; (3) approximate the whole workspace as an n-fold convolution of these densities. We represent density functions as finite Hermite-Fourier Series and show for the planar case how the n-fold convolution can be performed in closed form requiring O(n) computation time. If all segments are identical the computation time reduces to O(logn).
Vibration Centers for Planar Motion
Authors: Blanchet Pat , Lipkin Harvey
Published: February 2021

A novel analysis is presented for the planar free vibration of an elastically suspended rigid body. Vibration centers describe the modes shapes and are shown to be constrained to regions specified by the center-of-elasticity, center-of-mass, and stiffness principal directions. Responses are classified by the number of pure translational modes and conditions for existence are given. Numerical examples illustrate the results.
Remote Center of Compliance Reconsidered
Authors: Ciblak Namik , Lipkin Harvey
Published: February 2021

Remote center-of-compliance devices have long been used to facilitate insertion for assembly operations. A new analysis with a more accurate model better characterizes the interesting properties of remote compliance. The center location and stiffnesses are presented as nondimensional ratios that are only functions of geometrical properties and Poisson’s ratio. Important results show: i) the high sensitivity of the center location and ii) the inverse relationship between linear and angular lateral stiffnesses.
Analytical Criteria for the Analysis of Design Propagations in Mechanisms
Authors: Zou Hong-Liu , Abdel-Malek Karim , Wang Jia-Yi
Published: February 2021

A broadly applicable formulation for investigating design propagations in mechanisms is developed and illustrated. Analytical criteria in terms of the variations of joint position vectors and orientation matrices for planar and spatial mechanisms are presented. Mechanisms are represented using graph theory and closed loops are converted to a tree-like structure by cutting joints and introducing new constraints. The Jacobian matrix in Cartesian space is then transformed to Joint coordinates space. Two cases are considered: a pair of bodies remain connected by one joint after cutting additional joints and a pair of bodies are disconnected after cutting joints. Using this method, a designer has the ability to study the propagated effect of changing a design variable on the design. The presented formulation is validated through a numerical example of a McPherson strut suspension system. The system is analyzed and an assembled configuration is computed after a change in design.
C
2 Piecewise Bézier Harmonics for Motion Specifications of High-Speed Cam Mechanisms
Authors: Ge Q. J. , Srinivasan L.
Published: February 2021

This paper deals with the problem of specifying motions for high-speed cam mechanisms where reduction of vibration is a major concern, ft presents Bézier harmonic curves and C2 piecewise Bézier 3-harmonic curves for synthesizing cam-follower motions with low-harmonic content. As examples, these curves have been applied to the synthesis of Rise-Dwell-Return (RDR) cam motion program to demonstrate the flexibility and ease-of-use of the curves. It has also been shown that these curves have considerably lower harmonic contents than those of 3-4-5 polynomials at high frequencies. The results are useful for motion specifications of high-speed machinery including not only cam mechanisms but robot manipulators as well.
Trajectory Pattern Based Simultaneous Kinematic and Dynamic Optimal Design of High Speed Manipulators
Authors: Tai M. , Rastegar J.
Published: February 2021

An integrated structure and motion pattern specific design approach is proposed for optimal design of high speed and accuracy computer controlled machines including robots. The approach is based on the Trajectory Pattern Method (TPM). The current approach to the design of such machines is to assume that the machine will be required to perform more or less any arbitrary and often unrealistic tasks. This assumption nearly always leads to designs based on the worst operating conditions. The proposed trajectory pattern based design methodology presented in this paper stems from a fundamentally new design philosophy. The philosophy behind the proposed approach is that machines in general and ultra-high performance machines in particular must only be designed to perform a class or classes of motions effectively. And that trajectory patterns, i.e., classes of parametric trajectories, exist with which high speed motions can be synthesized with minimal ensuing vibration and control problems. In the proposed approach, given the kinematic structure of the machine, its kinematic and dynamic parameters are optimized simultaneously with the parameters that describe a selected trajectory pattern. The controller parameters may also be included as design variables. In the present study, the optimality criterion employed is based on minimizing the higher harmonic portion of the actuating forces (torques) required for performing the selected class(es) of motion patterns. Trajectories that do not demand high frequency actuating torque harmonics are desirable since they reduce vibration and control problems in high performance systems and reduce settling time. Examples of the application of the proposed approach are presented.
Dynamic Response of Multi-Cylinder Engines As Spatial Elastic Linkage Systems
Authors: Bagci Cemil , Rajavenkateswaran Siva K.
Published: February 2021

Dynamics of multi-cylinder engines have been performed by the conventional methods using lumped pure torsional systems. This article offers a finite element method of performing elastodynamic analysis of multi-cylinder engines considering them as spatial linkage systems with true spatial geometries of the crankshaft and the linkage loops. An engine can have any number of cylinders with linear offsets and angular orientations relative to each other. A three-dimensional finite-line element with isoparametric joint irregularity freedoms is developed and used. Consistent or lumped mass systems can be used. Elastodynamics of engines is considered in two forms: (a) kinetoelastostatics (KES) where all forces and torques acting on the system are considered except the vibratory motion effect; (b) kinetoelastodynamics (KED) where the forced and damped equations of motion of the system are solved. Matrix exponential method of solving equations of KED motions are presented and used. It is proven to be a very efficient and stable technique for the solutions of large systems of linear and nonlinear differential equations of any order. After solving for the generalized coordinates, time histories of the neutral coordinate displacements, forces, moments, stresses, bearing forces, and generated torque are determined for as many work cycles as desired. A generalized computer program performing KED and KES studies of any multi-cylinder engine is made available for industrial use. KED and KES analyses of a four-cylinder automobile engine are performed.
Complete Shaking-Force, -Moment, and, -Torque Balancing of Multi-Cylinder Engines Without Requiring Harmonic Balancers
Authors: Bagci Cemil
Published: February 2021

Conventional engine balancing process truncates the piston acceleration to form harmonics form for the shaking force; then using dynamically equivalent two-particle mass system for the connecting rod, the shaking force is balanced by arranging the phase angles of the crank throws. During this process, the shaking torque balancing (about the crank shaft axis) is ignored. Shaking force due to truncated portion of piston acceleration is left unbalanced; and that some phase angle arrangements cannot balance the harmonics of the shaking force. This requires force harmonic balancers. Unbalanced inertial forces generate shaking moment about the transverse axis (normal to crankshaft axis) that remains unbalanced. Shaking moment due to force harmonics for some phase angles also remain unbalanced. They require moment harmonic balancers.

This article presents a complete balancing method by which shaking force in each slider-crank loop is completely balanced. This also means that shaking moment is also completely balanced, thus eliminating the need for both force-, and moment-harmonic balancers. Article uses linearly independent mass vector method to retain the total center of mass of each slider-crank loop stationary. Shaking torque (sum of the inertial torques about the axis parallel to the crankshaft axis) causes variation in the output torque generated. This variation may be considered when designing the flywheel. However, the shaking torque is also balanced (or minimized) retaining the total angular momentum of each loop constant by arranging the phase angles of the crank throws. Several multi-cylinder engines are completely balanced for shaking force, shaking moment and shaking torque in the application examples, including balanced designs of connecting rod and throw sides.