bluuebunny/crossref_metadata_2025_split huggingface dataset:
Algebraic Motion Approximation With NURBS Motions and its Application to Spherical Mechanism Synthesis
Authors: Ge Q. Jeffrey , Larochelle Pierre M. 
Published: February 2021

Abstract
In this work we bring together classical mechanism theory with recent works in the area of Computer Aided Geometric Design (CAGD) of rational motions as well as curve approximation techniques in CAGD to study the problem of mechanism motion approximation from a computational geometric viewpoint. We present a framework for approximating algebraic motions of spherical mechanisms with rational B-Spline spherical motions. Algebraic spherical motions and rational B-spline spherical motions are represented as algebraic curves and rational B-Spline curves in the space of quaternions (or the image space). Thus the problem of motion approximation is transformed into a curve approximation problem, where concepts and techniques in the field of Computer Aided Geometric Design and Computational Geometry may be applied. An example is included at the end to show how a NURBS motion can be used for synthesizing spherical four-bar linkages.
A Dual Ellipse Is a Cylindroid
Authors: Ghosal Ashitava , Ravani Bahram 
Published: February 2021

Abstract
In this paper, we take a relook at two-degree-of-freedom instantaneous rigid body kinematics in terms of dual numbers and vectors, and show that a dual ellipse is a cylindroid. The instantaneous angular and linear velocities of a rigid body is expressed as a dual velocity vector, and the inner product of two dual vectors, as a dual number, is used. We show that the tip of a dual velocity vector lies on a dual ellipse, and the maximum and minimum magnitude of the dual velocity vector, for a unit speed motion, can be obtained as eigenvalues of a positive definite, symmetric matrix whose elements are the dual numbers from the inner products. From the real and dual parts of the equation of the dual ellipse, we derive the equation of a cylindroid (Ball,1900).
A New Method of Task Specification for Spherical Mechanism Design
Authors: Tse David M. , Larochelle Pierre M. 
Published: February 2021

Abstract
In this paper we present a novel method for motion generation task specification for spherical mechanisms. This is accomplished with a new methodology for determining the optimal design sphere and the orientations on this design sphere for a finite set of desired spatial positions. In addition, we include a modification to the method which enables the designer to require that one of the n desired spatial positions be exactly preserved. The result is that designers can now specify spherical mechanism motion generation tasks without having to introduce into the design space an artificial design sphere. They are now free to work in unconstrained three-dimensional space. The application of this new task specification technique is discussed in a design case study.
Accurate Determination of Object Position From Imprecise Data
Authors: Gupta Krishna C. , Chutakanonta Puckpol 
Published: February 2021

Abstract
The problem of accurate determination of object position from imprecise and excess measurement data arises in kinematics, biomechanics, robotics, CAD/CAM and flight/vehicle simulator design. Several methods described in the literature are reviewed. Two new methods which take advantage of the modern matrix oriented software (e.g. MATLAB, IMSL, EISPACK) are presented and compared with a “basics” method. It is found that both of the proposed decomposition methods (I: SVD/QR and II: SVD/QS) give better absolute results than a “basic” method available from the text books. On a relative basis, the second method (SVD/QS Decomposition) gives slightly better results than the first method (SVD/QR Decomposition). Examples are presented for the cases when the points chosen are nearly dependent and when the independent points have small random errors in their coordinates.
Kinematic Fixturing With Respect to a Plane Using Contact Sensing
Authors: Nederbragt Walter W. , Ravani Bahram 
Published: February 2021

Abstract
This paper presents a method for determining the location of geometric elements that compose the external features of referencing fixtures. Since in most applications parts that are handled in robotic work-cells are on a worktable or a floor, this paper focuses on fixture geometries that reside on a plane of known location. The location of the unknown geometric elements are found using contacts to the geometric elements and spatial constraints between the geometric elements. Geometric equations for contacts between lines, planes, points, spheres, and cylinders are derived. Spatial constraint equations are also derived. An algorithm is given for locating the geometric elements that form the fixture. The algorithm uses the contact equations and spatial constraint equations to locate the geometric elements. To illustrate the use of this algorithm, two examples are described in detail.
The Topological Structure Code Permutation Group Method of Polyhedral Solid for Identification of Kinematic Chains Isomorphism
Authors: Liu Chuan-He , Yang Ting-Li 
Published: February 2021

Abstract
This paper puts forward a new method for identification of kinematic chains isomorphism, which is called the topological structure code permutation group method of polyhedral solid. It can be put into practice by means of computer, and it is exact, dependable, quick and efficient. When isomorphism of two kinematic chains is identified by the method, it only need determine whether one permutation can be found out or not between topological structure codes of the two kinematic chains, or determine whether adjoint codes of the two topological structure codes are equal or not, it need not find out a symmetry group at all. It applies to all kinds of non-separable closed kinematic chains that don’t contain compound hinges.
In this paper, a new concept called polyhedral solid is put forward, the polyhedral solid model is given, and a theorem that describes the relation of faces, vertices, edges and geometric solids of a connected graph is given and proved. This paper expounds the definitions and general forms of the topological structure code and its adjoint code, the methods and rules of coding, the procedure of generating them. It also expounds and proves the beingness, accuracy and the uniqueness of the topological structure code and its adjoint code and the necessary and sufficient condition and criteria of kinematic chains isomorphism as well. The algorithm and some typical examples for identification of kinematic chains isomorphism are given.
Establishment of Numeric Atlas and Synthesis for Planar 4-Bar Path Generator
Authors: Wu Chen , Chu Jinkui 
Published: February 2021

Abstract
Planar 4-bar crank-rocker mechanism is exampled to demonstrate how to establish a numeric atlas on the base of a new concept of basic dimensional type, which is originated by utilizing two discoveries that two groups of harmonic characteristic parameters of dimensional type (HCPDT) will have identical amplitude values but contrary phase values when (1) their corresponding dimensional type are identical but with normal and reverse assembling manner respectively, or when (2) length exchange of b (coupler) and c (rocker) occurs, resulting in such two dimensional types as (a,b,c,d) and (a,c,b,d) with the same assembling manner. Such a numeric atlas is composed of basic dimensional types of crank-rocker mechanism and their corresponding HCPDT. In fact, the two discoveries are also used to reveal inherent law of 4-bar curve cognate mechanisms.
Conception of Balanced Spring Mechanisms
Authors: Herder Just L. 
Published: February 2021

Abstract
Statically balanced mechanisms are well known in various appearances of counterweighed beams, and systems where undesired mass is balanced by means of compensation springs. Similarly, springs can be designed to balance other springs. Besides the application of spring force compensation, many other kinds of mechanisms can benefit from the concept of balanced spring mechanisms. This paper introduces a lucid and logical methodology for the conception of statically balanced spring mechanisms. Based on constancy of system potential energy, a set of elementary rules is derived for the modification of a standard configuration with idealized springs. A number of examples are included to illustrate the versatility of the methodology, and to demonstrate the application potential of balanced spring mechanisms in general mechanical engineering.
Closed-Form Inverse Kinematic Solution of Triple Octahedron Variable Geometry Truss Manipulators
Authors: Xu Li Ju , Duan Yang , Yang Sui Xian 
Published: February 2021

Abstract
In this paper the triple-octahedron variable geometry truss manipulator is presented and its inverse displacement analysis in closed form is studied, Input-output displacement equation in one output variable is derived. The solution procedure is given in detail. A numerical example is presented for illustration.
The Synthesis of Planar Parallel Manipulators With a Genetic Algorithm
Authors: Boudreau Roger , Gosselin Clément M. 
Published: February 2021

Abstract
This paper presents a genetic algorithm approach for the synthesis of planar three-degree-of-freedom parallel manipulators. A genetic algorithm is an optimization method inspired by natural evolution. As in nature, the fittest members of a population are given better chances of reproducing and transmitting part of their genetic heritage to the next generation. This leads to stronger and stronger generations which evolve towards the solution of the problem. For the applications studied here, the individuals in the population consist of the thirteen architectural parameters of the manipulators. The algorithm optimizes these parameters to obtain a workspace as close as possible to a prescribed working area. For each individual of the population, the geometric description of the workspace can be obtained. The algorithm then determines the intersection between the prescribed workspace and the actual workspace, and minimizes the area of the regions that do not intersect. The method is applied to two planar three-degree-of-freedom parallel manipulators, one with prismatic joints and one with revolute joints.
In-Parallel Manipulators: A Framework on How to Model Actuation Schemes and a Study of Their Effects on Singular Postures
Authors: Matone Ricardo , Roth Bernard 
Published: February 2021

Abstract
This paper is concerned with the modeling of actuation schemes and their effects on the singularities of in-parallel manipulators. We begin by presenting a framework on how to incorporate actuator location and drive mechanism into the kinematic model of in-parallel manipulators. We show how to obtain the model in joint (actuator) space given the corresponding representation in actuator (joint) space. Next we show that, for in-parallel manipulators, the locations of actuators can modify singular postures. We present necessary and sufficient conditions on how to transform a singular configuration into a non-singular one by simply changing actuators locations. Finally, we illustrate these concepts with the analysis and design of a five-bar in-parallel manipulator for which transmission ratios and drive mechanisms are selected in order to improve kinematic characteristics. The example illustrates the fact that the choice of actuation schemes influences the size, shape, and direction of the velocity ellipsoid. Consequently, this choice modifies the velocity distribution in the entire workspace.
Force Directed Design of Laparoscopic Forceps
Authors: Herder Just L. 
Published: February 2021

Abstract
Mechanical design usually applies a kinematic perspective. Desired motion is taken as point of departure for the type and dimension synthesis of a linkage. Next, actuators are added to enforce this motion at the desired velocity. In addition to this movement directed design approach, also desirable force configurations can provide a useful design perspective. Awareness of forces seems to stimulate the design of simple and efficient mechanisms. This paper aims to illustrate a simple form of a force directed design approach with an example from medical technology. A purely mechanical laparoscopic grasping instrument with extraordinary mechanical efficiency is presented, which enables surgeons to clearly perceive several physiological properties, such as stiffness of tissue and the pulse of arteries.
Cross-Over of Rope Around Drum in Multi-Layer
Authors: Luo Xu , Kokubo Kunio , Hongo Kaoru , Xia RungHain 
Published: February 2021

Abstract
Cross-over of rope wound on a drum in multi-layers, is analyzed by means of differential geometry and variational principle with movable boundaries. As a geometrically nonlinear problem of the linearly elastic rope, centerline of cross-over of rope is treated as a space curve, which is constrained by surface of the rope of the lower layer. Considering the parameters of the constraining surface, the bending energy of the cross-over and the virtual work of the non-conservative tensile force are obtained. Thereby the Euler equation of the variational problem is obtained, and is changed into an implicit form. Finally the expression for the centerline of the cross-over is formulated. An experiment is made to measure the central angle of the cross-over and the data are compared with the calculated value.
Design of a Novel Fixture for Part Referencing
Authors: Nederbragt Walter W. , Ravani Bahram 
Published: February 2021

Abstract
This paper presents a novel design for a practical tactile-sensing mechanical fixture. The fixture consists of two tactile-sensing surfaces, a cylindrical surface and a planar surface. A mathematical procedure is developed for constructing a reference frame using point-to-surface contact locations on the fixture and the geometry of the fixture. A numerical example is given to further illustrate the use of this approach. Finally, the design of the fixture is described and a picture of the laboratory demonstration unit is shown.
A Note on Trajectory Planning for Conservative Motion of Redundant Manipulators
Authors: Chyu Younker R. , Song Shin-Min 
Published: February 2021

Abstract
The conservative motion of a redundant manipulator has been a subject of research for many years. Up to the present time, a method which guarantees conservative motion for a redundant manipulator tracing an arbitrary trajectory has not been presented. Moreover, the implementation of any conservative motion trajectory planning in discrete time domain has not been adequately addressed. In this paper, a trajectory planning method which guarantees conservative motion and preserves minimum norm of joint rates for a redundant manipulator tracing a closed-loop trajectory is presented. This method includes two intermediate via points in each incremental movement so that the manipulator can precisely pass through, with constant joint accelerations, all incremental positions with minimum jerks. The tracking errors exist only at the via points but not at the incremental points. Thus, conservative motion is ensured. The overall tracking errors can be reduced by simply selecting a smaller increment. The presented method is simulated with a three-linked, planar redundant manipulator and the results are discussed.
Error Model for Rotating Reference Frame Sensors Employed in the Space Station Module, Rack-Insertion End-Effector
Authors: Brewer William V. 
Published: February 2021

Abstract
Flight dynamics projections depend on estimates of the mass and its location for everything launched. It has been decided that these estimates will be made with the assistance of measurements taken by sensors installed on the Rack Insertion End Effector (RIEE). This error model is used to estimate accuracy that might be expected from the titled sensor placement scheme, taken as a whole, given the errors of component sensors and their placement.
Numerical Synthesis of Binary Manipulator Workspaces Using the Fourier Transform on the Euclidean Motion Group
Authors: Kyatkin Alexander , Chirikjian Gregory S. 
Published: February 2021

Abstract
In this paper we apply the Fourier transform on the Euclidean motion group to solve problems in kinematic design of binary manipulators. We begin by reviewing how the workspace of a binary manipulator can be viewed as a function on the motion group, and how it can be generated as a generalized convolution product. We perform the convolution of manipulator densities, which results in the total workspace density of a manipulator composed of double the number of modules. We suggest an anzatz function which approximates the manipulator’s density in analytical form and has few free fitting parameters. Using the anzatz functions and Fourier methods on the motion group, linear and non-linear inverse problems (i. e. problems of finding the manipulator’s parameters which produce the total desired workspace density) are solved.
3D Collision-Free Trajectory Planning for Mobile Robot Based on Quadric Modeling
Authors: Hwang Kao-Shing , Tsai Ming-Dar , Ju Ming-Yi 
Published: February 2021

Abstract
A 3-D collision-free trajectory planning method for a mobile robot is proposed in the paper. The geometric shapes of the objects in the workspace are modeled as ellipsoids of 3-D quadric model for simple mathematical representation and easy geometric approximation. By a series of coordinate transformations between the mobile robot and obstacles, the collision detection problem in trajectory planning is reduced to test a point falling outside or inside the transformed ellipsoids, which models obstacles geometrically. Finally, the collision probability, which is defined by projecting the quadric ellipsoid onto a 3-D Gaussian distribution contour, plays a very significant role in search the optimal path through the defined objective function.
Design of a Tele-Robotic System for the Maintenance of Boiler Hoppers in Electric Power Plants
Authors: Saidi Kamel S. , Seo Jongwon , Sreenivasan S. V. , Haas Carl T. , Traver Alfred E. 
Published: February 2021

Abstract
The design of a novel tele-operated robotic device for clearing undesirable residues (known as clinkers) from the bottom of boiler hoppers in electric power plants is presented in this article. A key aspect of the problem that drives the design process is the fact that the environment inside the hopper is harsh and unstructured. The part of the device that goes into the boiler through a hatch door must be able to handle high temperatures, highly corrosive ash, and the possibility of large residues falling on the device which could lead to serious structural damage to the device. This has led to a new robot design which has all its sophisticated mechanical and control hardware located outside the boiler hopper access port. The only component that goes into the boiler is an inexpensive pole which is expendable and easily replaceable. Also, it can be pulled out from the hopper even if it is seriously damaged. A special insertion mechanism serves as a prismatic joint for inserting and extracting the pole. Forward (sensing) and inverse (control) kinematics problems that are unique to this new design are also presented. Finally, a discussion of the results from preliminary experimental testing in a laboratory setting is included.
An important component of the process of designing the robot was the inclusion of ideas from the currently practiced manual clinker clearing process. This was accomplished via periodic discussions with the plant workers who perform the manual process.
Determination of Principal Curvatures and Contact Ellipse for Profile Crowned Helical Gears
Authors: Feng Pin-Hao , Litvin Faydor L. , Townsend Dennis P. , Handschuh Robert F. 
Published: February 2021

Abstract
Helical gears with localized bearing contact of tooth surfaces achieved by profile crowning of tooth surfaces are considered. Profile crowning is analyzed through the use of two imaginary rack-cutters with mismatched surfaces. The goal is to determine the dimensions and orientation of the instantaneous contact ellipse from the principle curvatures of the pinion and gear tooth surfaces. A simplified solution to this problem is proposed based on the approach developed for correlation of principal curvatures and directions of generating and generated tooth surfaces. The equations obtained are applied to three cases of profile crowning where the normal profiles of the rack-cutters are: (i) parabolic curves: (ii) circular arcs; and (iii) a combination of a straight line for one of the rack-cutters and a parabolic curve or a circular arc for the mating rack-cutter. The gear drives can be the combination of a pinion generated by a parabolic curve or a circular arc and gear generated by one of three cases mentioned above.
Vibro-Acoustic Studies of Transmission Casing Structures
Authors: Crimaldi D. , Singh R. 
Published: February 2021

Abstract
Automotive transmission casing plates of irregular shape, with complex boundary conditions and non-uniform material properties, are experimentally and computationally studied to acquire a fundamental understanding of their dynamic and acoustic radiation characteristics. A modified flat cover is designed which simplifies the geometry while providing uniform thickness and material properties. Both covers (“real-life” and “laboratory”) are studied with free and bolted boundary conditions. In particular, the free boundary conditions are useful because they eliminate the cover-housing interaction allowing for a more detailed analysis of the cover plate. Finite element models for both covers under the free boundary conditions are developed and refined. Predicted natural frequencies and mode shapes are in excellent agreement with measured modal data. Then the finite element models are coupled with boundary element models to predict acoustic radiation properties. Predictions match well with measured acoustic directivity at resonant frequencies.
A Possible Strategy for Incorporating Edge Effects in Root Stress Estimation of Helical Gears
Authors: Kalluri Ravikiran , Houser Donald R. 
Published: February 2021

Abstract
This paper presents the development of a strategy to improve current root stress predictions at the edges of spur and helical gear teeth. Industry demands for higher power density gearboxes require maximum utilization of the load carrying capability of the gear. This requires an accurate understanding of the load distributions and the resulting root stresses. Current analytical methods for predicting root stresses include accurate but time-consuming three-dimensional finite element analysis and some special purpose gear programs. The special analysis programs are computationally faster but rely heavily on empirical mathematical formulations which do not easily lend themselves to the inclusion of edge effects. This effect is seen in the experimental and finite element results due to the difference in stiffness between the edges of helical gear teeth and increases with helix angle. Stress predictions from a state-of-the-art empirical program are compared with experimental and finite element results and a correction suggested for this discrepancy.