Showing papers on "Kinematics published in 1979"
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IBM1
TL;DR: Two methods for achieving straight line motions in manipulator control languages by interpolating intermediate points along the Cartesian straight line path at regular intervals during the motion, and solving the manipulator's kinematic equations to produce the corresponding intermediate joint parameter values.
Abstract: Recently developed manipulator control languages typically specify motions as sequences of points through which a tool affixed to the end of the manipulator is to pass The effectiveness of such motion specification formalisms is greatly increased if the tool moves in a straight line between the user-specified points This paper describes two methods for achieving such straight line motions The first method is a refinement of one developed in 1974 by R Paul Intermediate points are interpolated along the Cartesian straight line path at regular intervals during the motion, and the manipulator's kinematic equations are solved to produce the corresponding intermediate joint parameter values The path interpolation functions developed here offer several advantages, including less computational cost and improved motion characteristics The second method uses a motion planning phase to precompute enough intermediate points so that the manipulator may be driven by interpolation of joint parameter values while keeping the tool on an approximately straight line path This technique allows a substantial reduction in real time computation and permits problems arising from degenerate joint alignments to be handled more easily The planning is done by an efficient recursive algorithm which generates only enough intermediate points to guarantee that the tool's deviation from a straight line path stays within prespecified error bounds
305 citations
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TL;DR: Improvements in a Newton-Euler approach to spatial open-chain mechanism analysis introduced by one of the authors are presented, which are shown to satisfy a number of necessary conditions, thereby validating to some extent both the methodology and the corresponding computer program.
Abstract: This paper presents some improvements in a Newton-Euler approach to spatial open-chain mechanism analysis introduced by one of the authors in an earlier publication. The improvements have to do both with the introduction of simplified notation and with more efficient computational procedures. The validity and utility of the method is illustrated by an application to the problem of calculating joint torques for the legs of a hexapod locomotion system. The results obtained agree well with experimental measurements and are also shown to satisfy a number of necessary conditions, thereby validating to some extent both the methodology and the corresponding computer program.
236 citations
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TL;DR: In this paper, a purely kinematic model involving only one experimental constant is proposed for the description of the velocity field in a granular material discharging from a hopper, and experimental measurements have been made on velocity distributions on a two-dimensional hopper and excellent agreement with the model is found.
179 citations
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01 Feb 1979
TL;DR: An object-handling system for manual industry is described, designed to have a compact structure and to accomplish multiple prehension and flexible motion for manual tasks.
Abstract: An object-handling system for manual industry is described. This system is designed to have a compact structure and to accomplish multiple prehension and flexible motion for manual tasks. The system has three fingers which have structures similar to those of a human. Namely, these fingers are composed of three, four, and four joints, respectively, and can perform not only such simple motions as bending and extending but also such lateral flexing motions as adduction and abduction. The kinematics of the system is discussed in a rectangular coordinate system. The general solution for the finger joint is obtained by solving a fourth-degree equation. The control mode of each finger joint is suitably changed between position and torque control, and each joint is controlled by a hardware servo system. Cooperative motions among the fingers are easily realized by means of the hardware servo system. In an experiment of swing motion, cooperative motion based on a force control is accomplished between the right and left fingers without dropping the object. Bar turning and sphere turning are accomplished smoothly by a computer control in which control signals for finger joints are generated by interpolating a sequence of set points that has been stored in the computer in the teaching process.
162 citations
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TL;DR: The classification of mechanisms is reviewed and their kinematic structure and graph representation discussed in this article, where a mechanism creation based on the separation of structure from function is illustrated and discussed.
Abstract: The classification of mechanisms is reviewed and their kinematic structure and graph representation discussed Mechanism creation based on the separation of structure from function is illustrated f
153 citations
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TL;DR: A biomechanical investigation to determine the overall kinematic behavior of the human wrist or carpus is described and data for one normal subject and one rheumatoid patient, examined both pre and post operatively are presented and discussed.
110 citations
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TL;DR: In this article, a generalized kinematic channel network routing model was proposed to allow a flow relationship that describes both high and low-flow characteristics, and applied to the channel network of the Institute of Hydrology's River Severn experimental catchment.
Abstract: Field measurements suggest that the relationship between velocity and discharge in steep rough upland channels may be nonlinear at low-flow stages but approximately linear at high-flow stages. This paper describes a generalized kinematic channel network routing model which can allow a flow relationship that describes both high- and low-flow characteristics. The model is applied to the channel network of the Institute of Hydrology's River Severn experimental catchment and, for this specific application, proves to be equivalent to a linear model based on a constant kinematic flow velocity. A strategy for choosing and applying a flow routing model for use in small catchments is suggested.
105 citations
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79 citations
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TL;DR: The best least-squares fit to the model relating average electromyographic activity to forearm angular position, velocity and acceleration was obtained by assuming separate time delays for each kinematic variable.
66 citations
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TL;DR: A unified computer program is developed for the complete kinematic analysis of the wrist motion and the accuracy of the analysis is checked by using a known mechanical joint as wrist.
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TL;DR: The principles of an apparatus which incorporates orthogonal radiography with a method of placing and holding human subjects, and moving them through easily indexed ranges of motion are described.
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TL;DR: In this paper, the authors present a technique which produces explicit Lagrange or Hamilton equations for mechanism dynamics suitable for computer solution, which can be used to solve the Euler-Lagrange equation.
Abstract: The practical simplicity of obtaining equations of motion using the methods of Lagrange and Hamilton is lost in the algebra of the Euler-Lagrange equation when many nonlinear constraints exist among the physical coordinates in the energy state functions. Such is the case for mechanical systems containing kinematic mechanisms. This paper presents a technique which produces explicit Lagrange or Hamilton equations for mechanism dynamics suitable for computer solution. A general matrix description of mechanism kinematics and inertial properties permits the algebra of the reduction from physical to generalized coordinates to be performed symbolically or numerically by a digital computer. The physical inertia transformed into properties associated with the generalized coordinates of the mechanism displays both physical and artificial behavior to account for conservation of momentum, kinetic co-energy and energy. The method produces equations efficient for numerical calculation and provides insight into the complex inertial dynamics of mechanisms. Vector bond graphs provide a conceptual basis for the technique and describe the energetic structure of the equations. A numerical example illustrates the procedure and results.
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01 Feb 1979TL;DR: This paper uses an additional method for describing the kinematics of head motion through the use of Frenet-Serret frame fields and derived three-dimensional motion of the head, during and after impact, was derived from experimental measurements and expressed as kinematic quantities in various reference frames.
Abstract: The response of the head to impact in the posterior-to-anterior direction was investigated with live anesthetized and post-mortem primates. The purpose was to relate animal test results to previous head impact tests conducted with cadavers and to study the differences between the living and post-mortem state in terms of mechanical response. The three-dimensional motion of the head, during and after impact, was derived from experimental measurements and expressed as kinematic quantities in various reference frames. This paper uses an additional method for describing the kinematics of head motion through the use of Frenet-Serret frame fields. The experimental technique used a nine-accelerometer system, mounted rigidly to the head, to measure head motions. Additional measurements included impact force, epidural pressure, and strains in the skull bone. Language: en
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TL;DR: A technique for clinical evaluation of gait by relatively simple means is developed and the six components of the ground reaction forces were chosen for an analysis, with a major tool the time integral of the forces.
Abstract: The kinematic and dynamic aspects of human locomotion have been investigated during the last eighty years. Significant contributions were made towards the understanding of the mechanics of movement and of the joints. As a consequence the field of Rehabilitation and Orthopaedic Biomechanics advanced considerably. However the complexity of the kinematic and dynamic data of locomotion prevented the various techniques from becoming clinically applicable. This paper attempts to develop a technique for clinical evaluation of gait by relatively simple means. For this purpose the six components of the ground reaction forces were chosen for an analysis. The major tool of the technique is the time integral of the forces. Since this is a quantitative parameter with a distinct physical definition, it can be very meaningful as far as investment of efforts in ambulation is concerned. As a first step towards the reinforcement of this thesis a consistency test was developed. The consistency test ensures that the use of d...
01 May 1979
TL;DR: In this paper, the tractive forces between the terrain and the vehicle track are simulated by a rheological model that accounts for nonlinear shear-stress/shear-deformation relation, the effect of deformation rate on shearing resistance, and the impact of pressure on shear resistance and plastic yielding.
Abstract: : This report documents the development of a mathematical model for predicting the steering performance of track-laying vehicles in environments ranging from soft soils to hard surfaces such as rigid pavements. The tractive forces between the terrain and the vehicle track are simulated by a rheological model that accounts for nonlinear shear-stress/shear-deformation relation, the effect of deformation rate on shearing resistance, and the effect of pressure on shear resistance and plastic yielding. The rheological model is coupled with the kinematics and the characteristics of the vehicle to develop the equations governing the transient motion of a vehicle on a level flat surface and the steady-state turning motion on a sloping terrain. A computer program, named AGIL, numerically integrates and solves these equations of motion in terms of the kinematics of the problem. The computer program is used to investigate parametrically the steering performance of a specific vehicle on different types of terrain and to examine the effect of vehicle charcteristics on steering performance. Appendix A of this report presents a procedure for determining the coefficient of rolling resistance. Appendix B gives recommended stability criteria for uniform turning motion. The field direct shear device is described in Appendix C.
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TL;DR: In this paper, the analogies with articular and muscular mechanics of human limbs are pointed out, and a mathematical model with a computer program aids the study of kinematics and dynamics of the mechanical hand.
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01 Jan 1979••
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30 Apr 1979TL;DR: In this article, a kinematic inertial sensor is provided for measuring angular velocity and position relative to inertial space about one or more measurement axes, including angular rate sensor, signal generating means, torque applying means, angle measuring means, resolver means, component processing means and signal applying means.
Abstract: A kinematic inertial sensor is provided for measuring angular velocity and position relative to inertial space about one or more measurement axes. The kinematic inertial sensor includes an angular rate sensor having a ring of conducting fluid contained in a housing, a set of gimbals for supporting the angular rate sensor, signal generating means, torque applying means, angle measuring means, resolver means, component processing means, and signal applying means.
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01 Dec 1979TL;DR: In this article, the authors present an algorithm for the online optimal path control of a robotic manipulator using an array of Texas Instruments TMS9900 microprocessors and a global memory.
Abstract: This paper describes the implementation of an algorithm for the on-line optimal path control of a robotic manipulator using an array of Texas Instruments TMS9900 microprocessors and a global memory. In contrast to work by other investigators, this approach utilizes a horizontal decomposition which assigns a single processor to each joint for computing kinematics, but distributes the computation of control by coordinant axes. In the present configuration, the arm is modeled as a point mass under gravity loading and control is computed in Cartesian space utilizing minimum energy techniques.
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01 Jan 1979
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TL;DR: The aim of this paper is to introduce a method that enables the mathematical model automatically with the aid of a computer using only basic information about dimensions and variables.