bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preliminary Experiments on Using Direct Calibration As an Approach for Automated Windshield Loading
Authors: Murray William R. , Pohlhammer Christopher M. , Wilson Paul C. 
Published: February 2021

Abstract
Assembly experiments are described that were conducted to evaluate direct calibration, a straightforward approach to the calibration problem for sensor-guided assembly systems. In direct calibration, the entire assembly system — the robot, the sensors, and the parts to be assembled — is calibrated for the required assembly task in a single procedure to directly determine the relationship between the part feature information in sensor coordinates and the part location in robot coordinates. This calibration procedure is accomplished in two steps: calibration data are generated by using the robot to move the part(s) to be assembled under the view of the sensors; and the best-fit mapping representing this assembly process is determined.
In this research project, the method of direct calibration is applied to the use of a vision-guided robotic system to install windshields in automobiles. Glass installation on the automotive assembly line is a delicate and difficult-to-automate assembly task. In the approach to windshield loading proposed herein, direct calibration is used to provide robust estimates of the location of both the windshield and the windshield opening, or aperture, in the car body. This location information is used to modify the taught insertion path such that each windshield is inserted into the corresponding aperture in the same manner that the windshield at calibration was inserted into the aperture at calibration.
To evaluate direct calibration as an approach in windshield loading and to determine the level of performance achievable with common industrial hardware, simplified 3-DOF assembly experiments were conducted. Results from these preliminary experiments indicate that direct calibration is a promising technical approach for the industrial application of automated windshield installation.
Workspace Representation of Parallel Manipulators Using the Finite Twist Method
Authors: Singh H. , Dai J. S. , Kerr D. R. 
Published: February 2021

Abstract
A method has been developed that successfully represents the workspace of a parallel manipulator within a finite twist image space. A point in this space represents a unique position and orientation of the end effector. The method of analysis is based upon the established technique of simplifying the parallel manipulator, by modelling each leg as an independent serial manipulator. The workspace corresponding to each serial manipulator is mapped onto the image space to produce a hyper-volume. The intersection of the individual hyper-volumes represents the workspace of the complete parallel manipulator. Since the hyper-volume corresponds to all possible positions attainable by the end effector, this represents the reachable workspace. Within the reachable workspace there lies subsets of volumes in ⮲3 that correspond to all possible orientations attainable. Such volumes represent the dextrous workspace. Although the method is illustrated by the use of a Stewart platform, it is equally applicable to the general parallel manipulator. The method is demonstrated successfully by the use of a 3 legged, 3-DOF planar parallel manipulator.
Optimization-Based Grashof-Mechanism Synthesis via Sub-Type Specific Parameter Transforms
Authors: Podhorodeski Ron P. , Fang Xiaoqi 
Published: February 2021

Abstract
Transformations are developed to allow mapping from an unconstrained n-dimensional search variable set to n link length values describing a constrained linkage within a specific mechanism sub-type. The transformations are based on redefining link length limits, incorporating “Grashof-criteria” considerations, concurrently with the transformation of the unconstrained variable set values. The technique facilitates effective optimization allowing search and convergence within a preferred mechanism sub-type. A transform is presented for a Grashof four-bar (crank-rocker), the methodology being easily applied to other single and multiple-loop planar mechanisms. The developed transforms are demonstrated to be effective through application in the synthesis of mechanism dimensions for a deep-digging implement.
The Synthesis of a Transmission With Intersecting Axes for Rectifying and Reducing a Periodic Speed: A Preliminary Study
Authors: Teng ChinPun , Angeles Jorge , Khader Khaled 
Published: February 2021

Abstract
In power-transmission tasks, the mechanical designer faces sometimes the problem of transmitting a constant angular velocity from a shaft at the output of a motor to another shaft connected to the load. When the first shaft is connected to the rotor of the motor via a gear box directly, and the motor is supplied with an effective speed control system, then the problem of power transmission can be readily solved using a spur-gear train if the shafts are parallel; a bevel-gear train if the two shafts intersect; and a gear train with skew axes if the shafts are neither parallel nor intersecting. However, instances occur in practice whereby the rotor of the motor is connected to a speed reducer that does not preserve the constancy of the motor speed, e.g., when a sprocket-chain transmission is used. In these cases, the input speed is not constant, but periodic. This paper focuses on the design of a transmission mechanism that serves to rectify the periodic speed of an input shaft to deliver a constant speed to the load. Moreover, in doing this, we show that it is possible to reduce the speed delivered by the motor as well. The problem of power transmission between parallel axes was reported in an earlier paper. Here, we report work on the corresponding problem when the shafts intersect. In the two cases, a transmission based on cams is synthesised, this paper reporting on a design based on spherical cams.
Position Analysis and Higher-Order Synthesis of the Swinging-Block Mechanism
Authors: Benedetto Augusto Di , Pennestrì Ettore 
Published: February 2021

Abstract
Algorithms for graphical analysis and kinematic synthesis of the path generator swinging-block mechanism are proposed in this paper. In particular, through a blending of optimization procedures and higher-curvature properties of infinitesimal rigid motions, it is shown how such a mechanism may approximate symmetric continuous curves with up to two sets of four infinitesimally separated precision points. Thus the generated path has eight precision points in common with the ideal curve.
A New Class of Linkage With Synthesis Method for Exact Dwell Motion at 1-2 Limit Positions of Output Link
Authors: Zhang W. J. 
Published: February 2021

Abstract
Occasions still exist for a designer to select a purely mechanical means to realize some special motion types, such as exact dwell at limit positions of the output link. This happens particularly when the design emphasis is placed on highly reliability, high operation speed and low cost. In this paper, a new principle and synthesis method to develop a class of linkages which enable a relatively long exact dwell at 1-2 limit positions of output link are presented. It will be shown that with this new class of linkages, a longer exact dwell can be realized in comparison with those existing classes of linkages including cam mechanisms. Furthermore, a spatial input and output motion can be realized. Application of such a kind of linkage has been found in a package packing machine.
The Optimum Quality Index for the Stability of In-Parallel Planar Platform Devices
Authors: Lee Jaehoon , Duffy Joseph , Keler Max 
Published: February 2021

Abstract
The paper investigates primarily the geometrical meaning of the determinant of the Jacobian (det j) of the three connector lines of a planar in-parallel platform device using reciprocity. A remarkably simple result is deduced : The maximum value of det j namely, det jm is simply one-half of the sum of the lengths of the sides of the moving triangular platform. Further, this result is shown to be independent of the location of the fixed pivots in the base.
A dimensionless ratio λ = |det j| / det jm is defined as the quality index (0 ≤ λ ≤ 1) and it is proposed here to use it to measure “closeness” to a singularity.
An example which determines the optimal design by comparing different shaped moving platforms having the same det jm is given and demonstrates that the optimal shape is in fact an equilateral triangle.
Dynamic Modeling of Parallel Manipulators
Authors: Baiges Ivan J. , Duffy Joseph 
Published: February 2021

Abstract
The dynamic response is an important consideration when designing and controlling manipulators. This dynamic response can be better understood with the explicit equations of motion.
This paper presents the derivation of the explicit equations of motion for a parallel manipulator using Kane’s Method. These equations illustrate the high degree of coupling existing in this type of manipulator.
A simulation program is developed with the equations of motion and used for the inverse dynamic analysis of the system. The results of the tests indicate that the most important coupling effect is caused by gravity.
Force Distribution Characteristics of Actively Reconfigurable Wheeled Vehicle Systems
Authors: Sreenivasan S. V. , Nanua P. 
Published: February 2021

Abstract
This paper addresses the force distribution issues associated with redundantly actuated wheeled vehicles that are suited for operation on uneven terrain. Basic results relating to the partitioning of motion and force variables in these mechanisms are developed. The redundant actuation scheme allows for the control of force distribution in the system, in addition to motion control. The unique kinematic characteristics of wheeled systems, that makes these vehicles ‘singular’ on even terrain, and ‘near-singular’ on uneven terrain; and the presence of ‘kinematic slipping’ when these vehicles move on uneven terrain make their force distribution mathematics distinct from other systems considered in the literature. In a singular configuration, it is shown here that these active wheeled vehicles possess only a partial control over their internal force distribution. A procedure to partition the ‘force space’ into controllable and uncontrollable spaces is provided based on a geometric approach. Closed-form force space results are included for an actively articulated multi-module system (a generalization of a passive, articulated mobile robot that has been studied extensively in literature).
The force distribution in actively reconfigurable wheeled vehicles is closely related to their rate kinematics. Rate kinematics of these vehicles has been studied in a companion paper [SN96].
On the Existence and Characteristics of Solution Paths at Algorithm Singularities
Authors: O’Neil Kevin A. , Chen Yu-Che , Seng Jiaqing 
Published: February 2021

Abstract
The Extended Jacobian method is a popular approach for controlling a kinematically redundant arm which allows one to resolve redundancy by locally optimizing an objective function and to gain repeatability for a cyclic end effector trajectory. It is a special case of a family of methods called constraint function methods. It has been found that the occurrence of algorithmic singularities can cause severe difficulties and the advantages of the methods such as repeatability might no longer exist. The purpose of this analysis is to study the characteristics of algorithmic singularities, especially ones where only one rank is lost. We establish sufficient conditions for the existence of a joint path at an algorithmic singularity. The phenomenon of branch repeatability is shown to occur at an algorithmic singularity. We also show that the extended Jacobian method cannot successfully optimize the objective function beyond the singularity without loss of continuity of the joint derivative. Simple examples are given to demonstrate the use of our theoretical results.
The Effects of Actuation Schemes on the Kinematic Performance of Manipulators
Authors: Matone Ricardo , Roth Bernard 
Published: February 2021

Abstract
This paper is concerned with the effects of actuation schemes on three measures of kinematic performance which depend upon a manipulator’s Jacobian matrix (namely, the minimum singular value, the manipulability, and the condition number.) We begin by presenting a simple framework on how to incorporate actuator location and drive mechanisms in the kinematic model. Then, we redefine the performance measures using the new model. For each measure we derive properties relating its joint space to its actuator space description. Next we demonstrate that the choice of actuation scheme influences the size, shape, and direction of the velocity ellipsoid of the end-effector. Finally, we employ the above concepts in the design of a 2R planar mechanical arm. Its transmission ratios and drive mechanisms are selected in order to obtain good kinematic characteristics. We show that the choice of actuation scheme can be used to improve kinematic performance.
The Problem of Scheduling Parallel Computations of Multibody Dynamic Analysis Is NP-Hard
Authors: Liu Jin-Fan , Abdel-Malek Karim A. 
Published: February 2021

Abstract
A formulation of a graph problem for scheduling parallel computations of multibody dynamic analysis is presented. The complexity of scheduling parallel computations for a multibody dynamic analysis is studied. The problem of finding a shortest critical branch spanning tree is described and transformed to a minimum radius spanning tree, which is solved by an algorithm of polynomial complexity. The problems of shortest critical branch minimum weight spanning tree (SCBMWST) and the minimum weight shortest critical branch spanning tree (MWSCBST) are also presented. Both problems are shown to be NP-hard by proving that the bounded critical branch bounded weight spanning tree (BCBBWST) problem is NP-complete. It is also shown that the minimum computational cost spanning tree (MCCST) is at least as hard as SCBMWST or MWSCBST problems, hence itself an NP-hard problem. A heuristic approach to solving these problems is developed and implemented, and simulation results are discussed.
A Parallel Manipulator With Only Translational Degrees of Freedom
Authors: Tsai Lung-Wen , Stamper Richard 
Published: February 2021

Abstract
This paper presents a novel three degree of freedom parallel manipulator that employs only revolute joints and constrains the manipulator output to translational motion. Closed-form solutions are developed for both the inverse and forward kinematics. It is shown that the inverse kinematics problem has up to four real solutions, and the forward kinematics problem has up to 16 real solutions.
The Kinematics of Active Surfaces: Hyper-Redundant In-Parallel Manipulators
Authors: Smith David R. , Parziale Peter C. 
Published: February 2021

Abstract
Active surfaces are introduced, defined, and modeled as a cooperating set of parallel manipulators. In this context, active surfaces may be viewed as a means of approximating complex shapes or as hyper-redundant in-parallel force manipulators for modal vibration control. Such surfaces may be employed to correct for support structure deformations or vibrations, as well as to achieve other shape dependent performance requirements. As a result of these features, active surfaces have applications in many types of intelligent structures, such as telescopes, communications antennas, bridges, and airfoils. The paper provides an overview of the kinematics of active surfaces. Additionally, it outlines the vibration control problem, and demonstrates how active surfaces can be employed as a modal force manipulator.
Follow-the-Leader Control for the Payload Inspection and Processing System
Authors: Williams Robert L. , Tamasi Gabor 
Published: February 2021

Abstract
This paper presents a follow-the-leader algorithm for control of the Payload Inspection and Processing System (PIPS) at NASA Kennedy Space Center. PIPS is an automated system, programmed off-line for inspection of Space Shuttle payloads after integration and prior to launch. PIPS features a hyper-redundant 18-dof serpentine truss manipulator capable of snake-like motions to avoid obstacles. Given an obstacle-free trajectory for the manipulator tip, the follow-the-leader algorithm ensures whole-arm collision avoidance by forcing ensuing links to follow the same trajectory. This paper summarizes modular development, implementation, testing, and graphical demonstration of the algorithm for prototype PIPS hardware.
Design of a Cleaning and Homogenization Robot for Large Oil Storage Tanks
Authors: Qin Y. , Rastegar J. , Khorrami F. 
Published: February 2021

Abstract
A number of methods are currently employed for cleaning and inspection of large fuel storage tanks. All of these methods require that the tank be first taken out of service, emptied, the present sludge material removed, vented, and cleaned before the inspection process is undertaken. This process is very time consuming, laborious and costly. In addition, there is a great safety concern for people that have to operate the machinery inside the tank. In this paper, the design of a novel robotic system for cleaning large crude and # 6 oil storage tanks through regular homogenization that also prepares the tank surfaces and weld line for in-situ inspection is presented. The developed system is shown to not only reduce the direct and indirect cost of fuel tank cleaning and inspection, but also greatly reduce the amount of solid waste that has to be disposed of at high cost and with potentially high adverse environmental impact. This design solves most of the problems associated with the presently available telerobotic systems for similar operations since it makes it possible for the operator to be in constant visual contact with the robot operating within the tank. This novel design also greatly reduces the logistics problems related to the tether line and its handling within the tank and its entanglement. A prototype of this system is under construction.
Using Burmester Theory in the Design of Compliant Mechanisms
Authors: Mettlach Gregory A. , Midha Ashok 
Published: February 2021

Abstract
Compliant mechanisms have been defined as mechanical systems that derive some or all of their mobility from the flexibility of one or more of their members. In general, due to the large-deflection nature of the compliant members, analysis and synthesis of compliant mechanisms have typically required a numerical iterative solution method. Recently, analytical loop-closure synthesis techniques have been extended to the design of compliant mechanisms, by utilizing the concept of an equivalent pseudo-rigid-body model for a compliant mechanism. These developments have greatly simplified the synthesis of compliant mechanisms. These mechanisms have been synthesized for three precision points using analytical and graphical methods. In rigid-link mechanism design, additional precision points may be incorporated by using Burmester theory. With this enhancement as the motivation, this paper presents the first use of Burmester theory to design compliant mechanisms for four and five precision points. This is facilitated by use of the concept of an equivalent pseudo-rigid-body model. Burmester theory yields a linear set of kinematic equations, allowing for their easy utilization herein. Also for some design problems, this theory can provide a graphical representation of all possible solutions for compliant mechanisms. In addition to the specification of precision points for compliant mechanisms, input torque and/or potential energy values may also be prescribed.
Computing an Assembled Configuration for the McPherson Strut Suspension System
Authors: Zou Hong-Liu , Wang Jia-Yi , Abdel-Malek Karim A. , Alkam Moh’d 
Published: February 2021

Abstract
Geometry analysis for the kinematic design of the McPherson strut suspension system is presented. Analytical formulations for computing variational constraints of spatial joints are derived. Using this method, a designer may alter design variables and determine the propagated effect throughout the underlying mechanism. The McPherson suspension is represented using graph theory and closed loops are converted to a tree-like structure by cutting joints and introducing new constraints. A change in link length or link orientation is propagated through the model and a new assembled configuration is computed. The analytical formulation and its numerical solution methods are presented. The aim of this work is to provide the user of the experimental computer code with a method for the design and redesign of the McPherson suspension system.
Isotropic Coordinates, Circularity, and Bezout Numbers: Planar Kinematics From a New Perspective
Authors: Wampler Charles W. 
Published: February 2021

Abstract
It is commonly recognized that a convenient formulation for problems in planar kinematics is obtained by considering links to be vectors in the complex plane. However, scant attention has been paid to the natural interpretation of complex vectors as isotropic coordinates. These coordinates, often considered a special trick for analyzing four-bar motion, are in fact uniquely suited to two new techniques for analyzing polynomial systems: the BKK bound and the product-decomposition bound. From this synergistic viewpoint, a fundamental formulation of planar kinematics is developed and used to prove several new results, mostly concerning the degree and circularity of the motion of planar linkages. Useful for both analysis and synthesis of mechanisms, the approach both simplifies theoretical proofs and facilitates the numerical solution of mechanism problems.
Synthesis of Four-Bar Function Generators by an Iterative Learning Control Procedure
Authors: Phan Minh Q. , Chew Meng-Sang 
Published: February 2021

Abstract
This paper investigates the applicability of learning control theory to mechanism synthesis via the classical four-bar function generator problem. A function to be generated by a mechanism can be looked upon as a trajectory to be tracked. The parameters that define the mechanism can be thought of as the control inputs. In this sense, the problem of synthesizing a mechanism to generate a particular output function can be treated as a “control” problem. Moreover, it is a learning control problem if the mechanism is synthesized by an iterative process. At each trial or iteration, a learning scheme modifies the mechanism dimensions based on how well it generates the desired function in the previous trial so that the synthesized mechanism approximates the desired output function more and more closely. With this thinking, concepts and tools from learning control theory can be adapted to the mechanism synthesis problem. It will be shown that mechanisms with minimum residual error or minimum structural error can be synthesized by a procedure analogous to that derived for iterative learning control. The starting angles of the input and output links are learned together with the mechanism dimensions. By the use of weighted cost functionals, iterative learning schemes that handle the tradeoff between the emphasis on a certain portion of the output trajectory (e.g., local control) and the mechanism dimensions can be derived in a straight forward manner. Numerical examples are used to illustrate the utility and flexibility of the learning formulation.