bluuebunny/crossref_metadata_2025 huggingface dataset:
A Potential Field Method for Path Planning Into Cavities Defined by B-Splines
Authors: Butler Alley C. , LeClair Steven R.
Published: February 2021

This paper describes a potential field approach to robot path planning into cavities defined by B-splines. It discusses existing methods, and describes the development of a Voronoi tree using intersecting hodographs. The Voronoi tree is similar to the Voronoi diagram in that it is maximally distant from all objects in the robot’s environment, but the Voronoi tree is developed for cavities modeled by splines. By adding a potential field to the robot manipulator, a robot path can be found by seeking the manipulator position with the minimum value of the potential function. This position as defined by the potential field is also maximally distant from cavity walls. Results with the potential field method are discussed and conclusions are drawn.
Compensating Cleanup Tool Path
Authors: Zhu Xiaohong , Riesenfeld Richard F.
Published: February 2021

Today’s part geometries are becoming ever more complex and require more accurate tool path to manufacture. Machining process efficiency is also a major consideration for designers as well as manufacturing engineers. Although the current advanced CAD/CAM systems have greatly improved the efficiency and accuracy of machining with the introduction of Numerically–Controlled machining, excessive material may still be left on the finished part due to machining constraints, including the inaccessibility of the designed part geometry with respect the cutter, machine motion constraints like ramp angles, specific cutting patterns, etc. Polishing operations such as grinding and hand finishing are quite time consuming and expensive, and may damage the surface of the part or introduce inaccuracies because of human errors. While most of the existing machining approaches attempt to reduce such excessive restmaterials by modifying NC tool paths, none of them is satisfactory. They can be time–consuming, error prone, computationally intensive, too complicated to implement, and limited to certain problem domains. A compensating cleanup tool path will be developed in this research to automatically remove these excessive material from the finish part. This method greatly reduces the burden of hand finishing and polishing, and also reduces the error and complexities introduced in manually generating cleanup tool paths in the shop floor. More important, the tool path generated by this method will reduce the machining time, and increase tool life compared with optimized tool path which left no excessive material behind.
Support of Disassembly / Reassembly Evaluation Within Total Life Cycle Modeling Through Feature Neighborhoods
Authors: Otto Harald E. , Kimura Fumihiko , Mandorli Ferruccio
Published: February 2021

Current research trends are extending from partially integrated product and process modeling to life cycle modeling, in order to provide a framework and methodologies based on a holistic approach for the support of sustainable product development.

Within given scope we are interested to investigate, if feature technology, introduced in the late seventies and developed over the paste twenty years provides the potential, if further enhanced, to be used as a means to provide basic integration for geometry related processes and models over different product life cycle stages. In a first approach, feature neighborhoods are developed and introduced as an extension, to foster evaluation of disassembly / reassembly on grounds of feature-based product descriptions. An attempt to support product maintenance and material recycling within life cycle modeling while investigating structural dimension and limits of improved feature models as a means of geometry-based model integration.
An Architecture for Interoperability of Layered Manufacturing Data
Authors: Qian Xiaoping , Dutta Debasish
Published: February 2021

In this paper, we address the lack of interoperability of data in commercial layered manufacturing systems. Since it is a new field, all machines require users to deal with vendor specific softwares and data formats. We propose a simple architecture, one that already exists in the NC machining domain, to address this issue. Analogous to CLData, we propose LMData that is not vendor specific and can be used on a variety of LM machines. Implementation and examples are presented.
Simulation of Engine Assembly Clamping With a Detailed Cylinder-Head Multilayered Steel Gasket
Authors: Coquery Marie-Hélène , Polit Olivier , Touratier Maurice , Duysens Jacques , Magoni Pierre
Published: February 2021

A unique analytical and hierarchic methodology for mastering the clamping and the sealing analysis of an automotive engine block assembly is presented. The different levels of finite element modelisations are described; a flowchart of the entire process analysis focused on the cylinder-head multilayered metallic gasket technology is presented. Numerical results and correlation between these results and engine reliability tests and specific static tests are illustrated using the industrial application of a Renault engine to demonstrate the efficiency of the approach.
Optimal Structural Design of Compliant Mechanisms Considering a Quantitative Displacement Constraint
Authors: Ejima Susumu , Nishiwaki Shinji , Sekiguchi Minako , Kikuchi Noboru
Published: February 2021

Compliant mechanisms are a relatively new breed of jointless mechanisms in which the elastic deformation is intended to be a source of motion. In the past, flexible structural design optimization was considered only for the direction of the flexible point by using the material density or the homogenization method to identify the optimum layout. Here we shall extend this design theory to the case of a two dimensional design for compliant mechanisms which can specify the amount of deformation of the flexible portion. Finally, some examples are presented to confirm that the verification of optimal configuration using an image-based design method.
Globally Independent Coordinates for Real-Time Vehicle System Simulation
Authors: Serban Radu , Haug Edward J.
Published: February 2021

Models of the dynamics of multibody systems generally result in a set of differential–algebraic equations (DAE). State–space methods for solving the DAE of motion are based on reduction of the DAE to ordinary differential equations (ODE), by means of local parameterizations of the constraint manifold that must be often modified during a simulation. In this paper it is shown that, for vehicle multibody systems, generalized coordinates that are dual to suspension and/or control forces in the model are independent for the entire range of motion of the system. In addition to the immediate advantage of avoiding the computationally expensive redefinition of local parameterization, the existence of globally independent coordinates leads to efficient algorithms for recovery of dependent generalized coordinates. A topology based approach to identify efficient computational sequences is presented. Numerical examples demonstrate the improved performance of the proposed approach, relative to the conventional Cartesian coordinate formulation.
Incorporating Tribological Considerations in the Robust Concurrent Design of Automobile Engine Lubricated Components
Authors: Rangarajan Bharadwaj , Mistree Farrokh , Sorab Jagadish
Published: February 2021

Absence of any tribological considerations in design can lead to quality and durability problems in automobile engines, which arc unearthed only during the testing phase of an engine. The usage of an overall engine friction model in conjunction with robust design techniques facilitates the concurrent design of engine components with tribological considerations. The case study under investigation involves developing robust top-level design specifications with tribological considerations for principal lubricated components in an automobile engine. The Robust Concept Exploration Method is adopted as a framework to address tribological considerations in preliminary engine design, involving three major action items: design space exploration (design of experiments), system modeling (engine friction computer modeling and system approximation using response surface methods) and system synthesis (Compromise DSP). The usage of these action items helps in achieving an efficient and effective design process and makes possible exploration of different design scenarios. The details of the case study, the implication of the results and the conclusions that can be drawn, are elaborated in this paper. Our focus in this paper is to demonstrate a method of abstracting tribological issues to the preliminary stages of design, rather than the results per se.
Using Robust Design Techniques to Model the Effects of Multiple Decision Makers in a Design Process
Authors: Hacker Kurt , Lewis Kemper
Published: February 2021

In this paper we introduce a methodology to reduce the effects of uncertainty in the design of a complex engineering system involving multiple decision makers. We focus on the uncertainty that is created when a disciplinary designer or design team must try and predict or model the behavior of other disciplinary subsystems. The design of a complex system is performed by many different designers and teams, each of which only have control over a small portion of the entire system. Modeling the interaction among these decision makers and reducing the uncertainty caused by the lack of global control is the focus of this paper. We use well developed concepts from the field of game theory to describe the interactions taking place, and concepts from robust design to reduce the effects of one decision-maker on another. Response Surface Methodology (RSM) is also used to reduce the complexity of the interaction analysis while preserving behavior of the systems. The design of a passenger aircraft is used to illustrate the approach, and some encouraging results are discussed.
Novel Empirical Similarity Method for the Reliable Product Test With Rapid Prototypes
Authors: Cho Uichung , Wood Kristin L. , Crawford Richard H.
Published: February 2021

Contemporary industries are devoting increasing attention to the product development process, due to tight market shares and the abridged product life cycle. Reliable scaled product testing with rapid prototypes has the potential to improve these processes by replacing traditional costly and time-consuming product tests. In this context, rapid prototypes provide visual, ergonomic, and functional information with minimal time delay. Among the information classes, reliable functional information is least realized because of several features of rapid prototypes: (1) limited material choices and part size; (2) distinct material structure; (3) restrictive loading conditions; and (4) state-dependent material properties. To develop reliable functional tests, an improved similarity method is needed to overcome these limitations. The traditional similarity method, based on a Buckingham П approach, is commonly applied to perform scaled tests. In contrast to this method, wherein the state transformation between two similar systems is derived from dimensional vectors, we present a new similarity method that empirically derives the transformation from a geometrically simple specimen pair. The primary advantage of the new method over the traditional method is the capability to relate highly distorted systems. In this paper, the concept and theoretical framework of the novel similarity method are introduced, and two numerical examples demonstrate the new method.
A Method for Architecting Product Platforms With an Application to Interplanetary Mission Design
Authors: Gonzalez-Zugasti Javier P. , Otto Kevin N. , Baker John D.
Published: February 2021

Consider a group of products sharing common parts and assemblies. The products in question we call a product family, and the common elements, the platform. A platform architecture is the set of selection and configuration choices shared among multiple products. We present a method for designing product platforms that takes into consideration both the performance requirements as well as the cost of the product family. The definition of a product platform is formulated as a general optimization problem in which the advantages of designing a common base must be balanced against the constraints of the individual product variants and of the whole family. This optimization approach has been implemented as an interactive multi-team-based negotiation model for designing an interplanetary spacecraft platform and its supported family variants. The model is used to identify possible subsystems of each spacecraft that could be made common to all or some of the missions, and the impact of architecture decisions on the performance of the product family.
Spatial Correlation Metamodels for Global Approximation in Structural Design Optimization
Authors: Simpson Timothy W. , Allen Janet K. , Mistree Farrokh
Published: February 2021

Despite the steady and continuing growth of computing power and speed, the complexity and computational expense of engineering analysis codes maintains pace. Statistical techniques are becoming widely used in engineering design to construct approximations or metamodels of these analysis codes which are then used in lieu of the actual codes, facilitating optimization and concept exploration. Our purpose in this paper is to report results of ongoing research aimed at increasing the efficiency of computer-based engineering design through the use of spatial correlation metamodels to build global approximations of computationally expensive computer analyses. Three structural design examples are presented to test the predictive capability of these metamodels for use in design optimization. The reported results confirm that these spatial correlation metamodels can produce sufficient accuracy for optimization when used as global approximations.
A Unified Representation of Geometric Constraint Problems to Support Design and Manufacturing Applications
Authors: Bettig Bernie , Shah Jami
Published: February 2021

This research is based on the premise that a large number of problems in a variety of mechanical design and manufacturing domains can be mapped to a finite set of generic geometric problems. This paper presents only the representation aspects, which include not only the entities and their relationships at several levels of abstraction but also geometric tasks. To induce comprehensiveness we start at a very high level, listing many queries/commands arising in mechanical design and manufacturing and generalize these into a small set of generic queries/commands. In doing this we find it necessary to devise a new type of high level entity, the geometry characterization which is described with examples. To ensure tractability we start at a low level, describing primitive entities and constraints, and functions, and work our way up through compound entities and constraints. The end goal of this project is to produce an application independent system for geometric constraint solving and querying that can be integrated with any design or manufacturing application using a standardized representation.
Capturing Articulation in Assemblies From Component Geometry
Authors: Sinha Rajarishi , Paredis Christiaan J. J. , Gupta Satyandra K. , Khosla Pradeep K.
Published: February 2021

This paper presents a method to extract instantaneous articulation from part geometry, based on surface mating constraints as well as constraints imposed by other incidental contacts.

Many assemblies contain joints, each of which have degrees of freedom associated with them. These joints allow the relative positions of parts in the mechanism to change as the joints are articulated. Being able to represent these joints and their behavior is important from the designers perspective because it enables him or her to verify whether kinematic requirements have been met. Therefore, it is useful to be able to obtain such joint information directly from part geometry and contact physics.

The method presented here handles all lower pairs of kinematic joints. Surface mating contacts are classified into one of three types: planar, spherical and cylindrical. The contacts are represented by algebraic inequalities describing the translational and angular velocities at the contact. Non-penetration conditions are written for a finite set of points on the boundary of each contact face, and it is shown that the finite set of conditions is representative of the entire boundary and the region enclosed by the boundary. Simultaneous satisfaction of the non-penetration conditions at all the contact surfaces between a pair of bodies is represented by a 6-dimensional simplex, which can be solved using linear programming.
Design for Desired Mode Shapes: Preliminary Results
Authors: Lai Elizabeth K. , Ananthasuresh G. K.
Published: February 2021

This paper is concerned with the shape optimization of structures to attain prescribed normal mode shapes. Optimizing structural members in order to have desired mode shapes, besides the desired natural frequencies, is of interest in some applications at both macro and micro scales. After reviewing the relevant past work on the “inverse mode shape” problem, a feasibility study using the lumped spring-mass models and finite element models of an axially vibrating bar is presented. Based on the observations made in the feasibility study with bars, a meaningful optimization problem is formulated and solved. Using finite element analysis and numerical optimization, a method for designing beam-like structures for prescribed mode shapes is developed. The method is demonstrated with an example of designing the cross-sectional area profile of a beam along its longitudinal axis to get a desired fundamental mode shape. The nonuniqueness of the solution is noted and avenues for future research are identified.
A CAD/CAM Representation Model Applied to Tolerance Transfer Methods
Authors: Desrochers Alain
Published: February 2021

This paper presents the adaptation of tolerance transfer techniques to a model called TTRS for Technologically and Topologically Related Surfaces. According to this model, any three-dimensional part can be represented as a succession of surface associations forming a tree. Additional tolerancing information can be associated to each TTRS represented as a node on the tree. This information includes dimensional tolerances as well as tolerance chart values. Rules are then established to simulate tolerance chains or stack up along with tolerance charts directly from the graph. This way it becomes possible to combine traditional one dimensional tolerance transfer techniques with a powerful three-dimensional representation model providing high technological contents.
Optimization for Vibration Problems: Junction Layout of a Combined Structure Under Oscillation
Authors: Kawabe Yoshiko , Yoshida Shinobu , Saegusa Shozo , Kajiwara Itsuro , Nagamatsu Akio
Published: February 2021

Layout optimization of junctions yields the minimum number of junctions. And a fewer junctions means fewer joint components or fewer spot-welding operations, and this leads to higher production efficiency. A method is developed for optimizing the layout of junctions between two structures so as to minimize the relative displacement between them when one of them is oscillated by noise disturbances. A quadratic response function serves as the expected value of relative displacement between the two structures and as the objective function in the optimization process. A set of evenly distributed variable-spring elements joins the two solid structures in a single junction surface, and the distribution of elasticity indices is continually revised. After optimization, those spring elements with elasticity indices higher than a certain threshold are considered to represent rigid joints, while lower elasticity indices indicate the absence of any joints. The optimized elasticity-index distribution thus shows where to place junctions. Use of variable-strength spring joints like this makes it easier to determine optimum junction positions. This is because it eliminates the need to renew the entire FEM model for each case.
Tolerance Representation for Mechanism Assemblies in Layered Manufacturing
Authors: Rajagopalan Sanjay , Cutkosky Mark R.
Published: February 2021

By building parts up incrementally in layers or “compacts,” 3D layered manufacturing processes are capable of fabricating parts with complex internal geometry and multiple materials. Additionally, since parts are built fully embedded in a sacrificial support material, it is possible to fabricate fully assembled devices with multiple moving parts and mating/fitting surfaces (such as mechanisms). Given the method of manufacture, it becomes possible to provide designers of linkages with some flexibility in expressing constraints on the manufactured geometry of these parts. For example, designers now have the option of directly specifying the geometry of gaps and clearances with explicit tolerance assignments. In processes like Shape Deposition Manufacturing (SDM), these features are directly manifest in the geometry of the support structure. In many cases, it is these “shadow” features that most directly govern the behavior of the artifact being built. This paper explores the impact of in-situ manufacturing of assembled mechanisms on the tolerances required. Relaxation of the assemblability constraint is shown to result in looser manufacturing tolerances and better control over gap geometry for the specific instance of an isolated pin-joint.
Developing a DFX Course Using Structured Methodologies
Authors: Martin Mark V. , Ishii Kosuke
Published: February 2021

As part of the curriculum for a manufacturing program at Stanford, a Ph.D.-level course covering life-cycle design (also referred to as design for “X”) issues is required to be taken by students in the program. As a Ph.D. candidate doing research in this area, the first author (Martin) was asked to develop and teach this course. This paper discusses some of the issues in creating a new course and describes the use of structured methodologies (affinity diagrams, customer surveys, benchmarking, concept generation, and concept selection) in developing the course. Our goal in this paper is threefold: 1) to give an example of the use of structured methodologies in developing a course, 2) to show a sample curriculum for a dfX course, and 3) to present a framework describing course development.
The VR Factory: Discrete Event Simulation Implemented in a Virtual Environment
Authors: Kelsick Jason J. , Vance Judy M.
Published: February 2021

Virtual reality (VR) refers to an immersive, interactive, multi-sensory, viewer-centered, three-dimensional (3D) computer generated environment and the combination of technologies required to build such an environment (Cruz-Neira, 1993). Related to problems of engineering design and manufacturing, this new technology offers engineers the ability to work with computer models in a three-dimensional, immersive environment. This paper describes a virtual reality application where the results of a discrete event simulation of a manufacturing cell are integrated with a virtual model of the cell to produce a virtual environment. The program described in this paper, the VR Factory, allows the user to investigate how various changes to the manufacturing cell affect part production. This investigation is performed while immersed in a computer generated three-dimensional representation of the cell. This paper describes the creation of the VR model of the manufacturing cell, the animation of the environment and the implementation of the results of the discrete event simulation.
Determining the Value of Remanufacture in an Integrated Manufacturing-Remanufacturing Organization
Authors: McIntosh Mark W. , Bras Bert
Published: February 2021

In recent years, the concept of reusing products has received significant attention in academia as a means for reducing society’s negative impact on the environment. In fact, due to a number of both economic and environmental advantages to product reuse, some authors have proposed a larger role for reuse within society. In order to achieve an expanded role for product reuse, it will first be necessary to integrate remanufacturing capabilities into original equipment manufacturers (OEMs) such that reuse can be carefully planned by both product and process design. However, the implementation of OEM reuse is currently limited to the few examples that exist today by several barriers. These barriers include the problem of incomplete incentives due to the product disposal externality, the trends in production towards rapid innovation and mass customization, and the fact that remanufacture presents a fundamentally new set of challenges that producers are not prepared to deal with. It is our belief that reuse will not play a larger role in society until producers have both the incentives and ability to implement remanufacture given their business conditions. Providing this capability and these incentives will require a better understanding of how different factors impact remanufacturing operations within an OEM. This understanding can be provided through the improved modeling of remanufacture. In this work, a motivation and an algorithm for modeling how product design characteristics, product development strategies, and different business conditions impact remanufacturing viability is presented. The authors’ implementation of this model is described and the model is used to study a family of single use camera products over an eleven-year period in order to gain insight from a successful OEM remanufacturer.
Analytical Modeling for Semiconductor Wafer Fab Environments in Support of Drum-Buffer-Rope Implementation
Authors: Maguire Jay , Hinchman Jim , Luce Steve
Published: February 2021

A simple, practical analytical approach to capacity planning is described in the context of semiconductor wafer fabrication (fab) areas and implementation of Drum-Buffer-Rope methodology. The well validated model integrates bottleneck identification with predictors of headcount requirement, fab activity levels, cycle time and inventory curves, financial impacts and other metrics, as desired, for given volume and mix. The model, used in combination with the knowledge of local experts, provides information for medium or long range planning and for focusing improvement efforts for maximum effect. Opportunities for improvement are simply explained, verified, quantified and prioritized through the use of specific tool models and of Overall Equipment Effectiveness (OEE) as a measure of equipment performance. Several manufacturing areas on the same site can be simultaneously modeled, showing the effect of a change on the entire site.
An Experiment in Improving Student Estimation Skills
Authors: Smith David R. , D’Angelo John P. , DaSilva Robert A. , Sherwood James A.
Published: February 2021

In recent years, it has been suggested that engineering students are frequently unable to perform rough estimates. In an attempt to confirm and perhaps remedy this situation, we conducted an experiment into the estimation capabilities of upper-division Mechanical Engineering students in the Fall semesters of 1996 and 1997. The experiment sought to identify weaknesses in the abilities of students to recognize plausible results when performing calculations. Additionally, the experiment attempted to improve student estimation skills through exposure to estimation problems in both individual and group settings.

Specifically, the entire senior class was given an in-class estimation problem approximately once per week. At the end of the semester, a final estimation problem was given to this class, as well as to the entire junior class, and the results compared.

The initial results corroborate studies by others which indicate that students are frequently unable to estimate a solution within an order of magnitude. Indeed, a significant percentage are unable to even provide consistent units. Our experiment suggests that students can slightly improve their estimation skills through practice. More importantly, we found that students estimate significantly better when working in teams.
A Multi-Agent Interactive Approach to Assembly Modeling
Authors: Sfeir Neyla Antoine , Fujimoto Hideo , Iwata Akira
Published: February 2021

This paper introduces a new interactive multi-agent approach to automate the assembly modeling problem in order to generate the parts precedence relations of a product starting from its design data. Assembly parts are considered as self-interested intelligent agents with local information and goals. Centralized approaches based on graphical representation resulted so far in both combinatorial and information complexity, especially when dealing with actual complex industrial products. The proposed decentralized approach overcomes exhaustive combinatorial search, while the ability to store and exchange dynamic information among agents reduces the oversimplification of graphical representation. Furthermore, the incorporation of human agents helps the system to overcome the limitations of artificial intelligence. This approach offers a promising platform for assembly planning automation with minimum human intervention especially for all-new products.
Synchronization of Multiple Geneva Wheels in Parallel: Part I — A Novel Process
Authors: Sepahpour Bijan , Fischer Ian S.
Published: February 2021

Synchronization of the intermittent motion of multiple Geneva wheels in parallel by a single driver is presented. Three different types of drivers and their corresponding geometry are introduced. The characteristics of the generated synchronized motion of the multiple wheels actuated by each of the drivers are discussed. A special orientation of the multiple wheels and the single driver is proposed for optimizing the ratio of the synchronized index and dwell times of the output wheels. The assembly requirements of this approach are discussed. Correlation of the active/dwell times of the wheels are also considered. A comparison of the three types of drivers and the advantages of their applications is included. A condensed kinematic and kinetic analysis of Geneva mechanisms is presented for cohesion and continuity of the work in the appendix.
On the Generation of Identical Noncircular Pitch Curves
Authors: Tong Shih-Hsi , Yang Daniel C. H.
Published: February 2021

In this paper the theory and algorithm for generating pairs of identical noncircular conjugate pitch curves are presented. A set of criteria for two identical rigid bodies engaging in conjugate rolling motion is established. Based on these criteria, an algorithm is developed, which can be used to design this type of rolling pairs with almost unlimited profile varieties and any number of lobes. Geometrical conditions for having C1 (or slope) continuity at the intersections of tips and roots of lobe profiles are also established. A family of similar profiles can be designed at the same time by using a single parameter, the pitch noncircularity, via a dimensionless analysis. Results from this investigation should have applications to the design of noncircular gears and lobe pumps.
Using Dual Cam Tracks for High Speed Rigid Body Motion
Authors: Cooper Clay , Derby Stephen
Published: February 2021

Rigid Body Motion has long been one of the standard problems for kinematicians. For high speed transfer rates, an industrial example of using a dual cam track system to achieve better performance is documented. The dual track establishes both a positional and orientational location of the followers. The selection of this mechanism type is discussed.
A Method for Creative Design of Mechanisms and its Application
Authors: Shen Hui-ping , Xu Zhen
Published: February 2021

This paper presents an operable and practical similarity transplant creation method for creative design of mechanisms and mechanical structures. The theoretical basis and the procedures of this creation method are given. As an industrial example, the process of creation design of an expansion-contraction plugger designed by this method is discussed in detail. The method can be used in efficient solving one kind of mechanical creative design problems.
Modal Loss Factor Predication in Flexible Mechanism Systems With Constrain Viscoelastic Layers
Authors: Xianmin Zhang , Jike Liu
Published: February 2021

Control of dynamic vibration is critical to the operational success of many flexible mechanism systems. This paper addresses the problem of vibration control of such mechanisms through passive damping, using constrained layer damping treatment technique. A new type of shape function for three layer frame element containing a viscoelastic layer is developed. The equations of motion of the damped flexible mechanism are derived. Modal loss factors of this kind mechanisms are predicated from undamped normal mode by means of the modal strain energy method. Comparisons between the results obtained by this paper and the results obtained by exact solution of the governing equations for a well known sandwich beam demonstrate that the method presented in this paper is correct and reliable. Application of this method in predication of modal damping ratios for damped mechanisms is discussed. It is believed that the method of this paper hold the greatest potential for optimal design of damped flexible mechanism systems.
Inverse Force Analysis of General Planar Three-Spring System Using Continuation Method
Authors: Liu An-Xin , Shi Bao-Qian , Zhang Ming , Yang Ting-Li
Published: February 2021

The inverse force analysis of planar three-spring system is studied in this paper. First, the force balance equations and moment balance equations, together with the loop equations, are reduced into polynomial form. Then continuation method is used to find all static equilibrium positions of the system.
3D Dynamic Modelling of Flexible Gear-Bar Mechanical Systems: A Specific Finite Element Approach
Authors: Wang Y. , Zhang W. J. , Li Q.
Published: February 2021

A mechanical system considered here consists of gear, bar, shaft and bearing. The objective of the study is to develop a unified and systematic procedure to build a dynamic model for such complex mechanical systems taking into account as many as factors. These factors include the flexibility of all components and gear transmission errors. Existing literature provides a separate studies of dynamic behaviors on gear transmissions and multi-body systems (usually excluding gear transmission or at most considered as two disks with pure rolling). In this paper we propose to apply a specific finite element theory that has been widely successful in multi-body dynamics. This specific finite element theory promises that a dynamic model will be systematically established provided that an appropriate type of finite element is defined which of course should represent the dynamic features of a real world system. For this reason, we develop a new type of finite element that can describe the transmission behavior of a pair of gears with parallel axes. This new type of finite element is 3D, therefore we can demonstrate to build a dynamic model for such complex systems with consideration of rotational, transverse and axial deformations and gear transmission errors. A case study is provided.
A Numerical Scheme for Dynamic Systems Containing Fractional Derivatives
Authors: Yuan Lixia , Agrawal Om P.
Published: February 2021

This paper presents a numerical scheme for dynamic analysis of mechanical systems subjected to damping forces which are proportional to fractional derivatives of displacements. In this scheme, a fractional differential equation governing the dynamic of a system is transformed into a set of differential equations with no fractional derivative terms. Using Laguerre integral formula, this set is converted to a set of first order ordinary differential equations, which are integrated using a numerical scheme to obtain the response of the system. Numerical studies show that the solution converges as the number of Laguerre node points are increased. Further, results obtained using this scheme agree well with those obtained using an analytical technique.
Control of Robot Manipulators Using a Dual-Model-Based Structure
Authors: Li Q. , Zhang W. J. , Tso S. K.
Published: February 2021

This paper proposes a dual-model-based structure for uncertainty attenuation in the trajectory-tracking control of robot manipulators. A conventional model-based control algorithm with an estimated robot dynamic model employed is first placed in the overall structure as a basic control component. To further attenuate the unwanted effects caused by modelling uncertainties, another model-based structure, appended in the outer-loop of the basic control structure as a compensator, is developed based on the concept of the internal model control. Combination of these two model-based structures results in a novel dual-model-based controller for robot manipulators. Sensitivity analyses show that the effects due to both modelling errors and external disturbances can be significantly reduced by applying this dual-model-based control structure without relying on a high-gain control solution. Effectiveness of this control design is successfully demonstrated by simulation studies on a 2 degree-of-freedom robot.
Active Residual Vibration Control for Flexible Robot Manipulator Systems
Authors: Xianmin Zhang , Li Song , Jike Liu
Published: February 2021

In this paper, a mathematical model for flexible robot manipulators with smart links featuring piezoelectric films is developed in conjunction with the finite element method. The dynamics of piezoelectric actuators and strain gage sensors bonded on the flexible links are presented for beam model. Theory and measures of active vibration control for flexible manipulators are studied based on the modal and modern control theory, and the correspondent optimal control scheme is proposed. The robust control low is formulated based on the modified independent modal control method and the Linear Quadratic theory. The computational method for the actual control moments and the control voltages are also presented.
Singularities of a Manipulator With Offset Wrist
Authors: Williams Robert L.
Published: February 2021

The singularities of manipulators with offset wrists are difficult to enumerate. The wrist offset “skews” the known regional arm singularities and wrist singularities of the zero-offset case. This paper illustrates the problem for a specific example.
Orthonormal Isotropic Vector Bases
Authors: Ciblak Namik , Lipkin Harvey
Published: February 2021

Orthonormal bases of isotropic vectors for indefinite square matrices are proposed and solved. A necessary and sufficient condition is that the matrix must have zero trace. A recursive algorithm is presented for computer applications. The isotropic vectors of 3 × 3 matrices are solved explicitly. Deviatoric stresses in continuum mechanics, the existence of isotropic vectors (particularly in screw space), and stiffness synthesis by springs are shown to be related to the isotropic vector problem.
Application of Stiffness Decompositions to Synthesis by Springs
Authors: Ciblak Namik , Lipkin Harvey
Published: February 2021

Stiffness decompositions originating from two distinct eigenvalue problems are applied to stiffness synthesis by springs. The resulting free-vector and line-vector syntheses provide a clear geometric explanation of the methods. Numerical examples and algorithms are also provided to verify the results.
Structure Types Synthesis of Multiloop Spatial Kinematic Chains With General Variable Constraints
Authors: Luo Yufeng , Yang Tingli , Seireg Ali
Published: February 2021

A systematic procedure is presented for the structure type synthesis of multiloop spatial kinematic chains with general variable constraints in this paper. The parameters and the structure types of the contracted graphs and the branch chains used to synthesize such kinematic chains are given for kinematic chains with up to four independent loops. The assignments for the constraints values of all the loops in a kinematic chain are discussed. Using these as the basis, the structure types of the multiloop spatial kinematic chains with hybrid constraints could be synthesized.
A Geometric-Algebraic Exploration of Two Kinds of Schatz 6R Linkages
Authors: Lee Chung-Ching
Published: February 2021

The generation of two kinds of Schatz six-revolute linkages is first delineated from the view point of geometry and then, the general analytical kinematic closed-form solutions of both types are developed by matrix algebra and its differentiation for confirming the constrained motion and further application. The full cycle range of motion about the input link for these linkages is also verified by using the matrix differential closure loop equation. Furthermore, based on the six-by-six screw coordinate transformation matrix, we establish the algebraic formulas of screw coordinates of six-revolute joint axes and the single screw axis reciprocal to the five-order screw system defined by the joint axes of linkages. Then we make their algebraic and geometric analysis with the help of 3D computer graphics. Two kinds of algebraic surfaces for both linkages’ reciprocal screws are presented for understanding the real features and for proving the fact that during their cycles of movement there are no transversal to all six-revolue joint axes permanently.
Design of Spherical 4R Mechanisms: Function Generation for the Entire Motion Cycle
Authors: Farhang Kambiz , Zargar Yasir S.
Published: February 2021

A class of spherical 4R mechanisms are studied for which the crank is relatively smaller than the remaining links. The theory of small-crank mechanisms is applied to obtain approximate descriptions for the follower angular displacement in terms of the input crank angle. The follower angle is presumed to comprise a mean and a perturbational motion. This results in an approximate expression in which the follower displacement is given as a linear combination of simple harmonic functions of the first and second harmonics of the crank angle. The approximate equations are utilized for synthesis of spherical 4R mechanisms for function generation. In contrast to the conventional design procedures, the use of the approximate equations allows synthesis of spherical mechanisms in which the prescribed function is satisfied for the entire motion of the mechanism. In addition to design examples, sample error charts are provided to assist the designer in ascertaining feasible ranges for design and corresponding orders of error.
Identification of Singularity Free Joint Rotation Space of Two-DOF Parallel Manipulators
Authors: Dou Xiaohong , Ting Kwun-Lon
Published: February 2021

In this article, a novel approach is presented to identify the singularity free joint rotation space (JRS) of two-DOF seven-bar parallel manipulators. The configuration space of a seven-bar manipulator is expressed as joint rotation space sheets and each sheet may have one, two or four-sides. Each sheet represents a manipulator branch and each side of a sheet corresponds to a singularity free Joint rotation space. The article presents a logical approach to understand how the joint rotatability of one loop in a seven-bar manipulator is affected by the other loop, the formation of branches and its relationship to singularities. Based on the types of interaction between loops, manipulators are classified into three types. The paper offers an effective method to identify and understand the problems with branch and singularity of parallel manipulators. The concept and method can also be used in other types of parallel manipulators.
Analysis of the DLR Planetary Roller Spindle Drive
Authors: Balázs Matthias , Spieck Martin
Published: February 2021

The DLR Planetary Roller Spindle Drive (PRSD), a new linear actuator developed at the German Aerospace Center (DLR), transforms fast rotation of a drive into slow but powerful linear movement. To optimize dynamical behaviour and performance of modified PRSD design versions, modelling and calculation methods have been developed, taking into account the very special requirements of this new design.

To analyze the operating characteristics and performance figures, the DLR Planetary Roller Spindle Drive was modelled as a multibody system (MBS). Special attention was directed on the description of the complex contact mechanics between the PRSD elements. Accompanying experiments ensured the accuracy of the modelling. Analysis of the MBS model of an existing PRSD in the time domain showed satisfying accordance with testbench measurements.
Burmester Field Envelopes for Multiple Design Parameters
Authors: Mlinar John R. , Erdman Arthur G.
Published: February 2021

The Burmester field is the area swept by a Burmester curve as one or more of the design variables change. This paper presents the envelope of the Burmester field for more than one design parameter. It is shown that the envelope consists of various segments. These segments are found to be portions of Burmester curves and curves found using envelope theory. A two- and three-parameter example are provided and discussed. The application of the Burmester field concept to the design of linkages is also discussed. This includes the limitations on the selection of the second dyad.
A Parametrization Scheme for the Burmester Curves
Authors: Niyogi Siddhartha , Kinzel Gary L.
Published: February 2021

The cubic representation of the Burmester curve in Cartesian coordinates has certain disadvantages when automated searches are carried out. A parametric representation of the curve would be ideal. A systematic search could then be carried out by tracking points in a continuous fashion along the curve. In addition, solution rectification methods could be applied to determine the feasible segments, and the search could be limited to those portions only. This paper presents an alternative scheme for parametrizing the Burmester curves, as opposed to the complex number approach used by Chase et al. It uses the graphical method as its basis. The final scheme is not single valued, as it involves a parameter value as well a sign variable, but otherwise fulfils the requirements for an automatic search. It is an improvement on the cubic representation as it is double valued, rather than triple valued. The basic theory associated with the parametrization and the issues arising out of it are developed.
Solving the Kinematics of Planar Mechanisms
Authors: Wampler Charles W.
Published: February 2021

This paper presents a general method for the analysis of planar mechanisms consisting of rigid links connected by rotational and/or translational joints. After describing the links as vectors in the complex plane, a simple recipe is outlined for formulating a set of polynomial equations which determine the locations of the links when the mechanism is assembled. It is then shown how to reduce this system of equations to a standard eigenvalue problem, or if preferred, a single resultant polynomial. Both input/output problems and tracing-curve equations are treated.
Path Generation Using a Random Walk Algorithm
Authors: Camuto Matthew , Kinzel Gary
Published: February 2021

This paper develops a method for improved path generation utilizing optimization and rectification theory. Gradient based optimization methods with respect to path generation are examined and proved impractical by example. A random walk algorith is presented then tailored for path generation. By parameterizing the desired curve and utilizing this random walk algorithm results using gradient based methods are improved upon. An example using this algorithm is presented.