Browsing by Author "LIN, SK"

Now showing 1 - 9 of 9

A NEW COMPOSITE BODY METHOD FOR MANIPULATOR DYNAMICS
(1991-04-01)
LIN, SK
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
;
Institute of Electrical and Control Engineering
This article presents a new composite body method for numerically forming the inertia matrix and the bias vector of manipulators, which is more efficient than the other two existing types of composite body methods. The main discrepancy of this one from the existing ones is that all points in a manipulator are observed from the origin of the base frame and the distances are all measured from this origin. The required computations of the present method for the inertia matrix and the bias vector of a manipulator with n rotational joints are (10.5n2 + 38.5n - 85)M + (6n2 + 39n - 70)A and (12.5n2 + 5.5n + 3)M + (9n2 + n)A, respectively, where "M" denotes multiplications, "A" does additions. In numerically forming the inertia matrix, the present method is more efficient than other methods in the literature for a manipulator with five or more joints; whereas this method is also superior to the recursive Newton-Euler formulation in computing the bias vector for a manipulator with six or less joints.
AN APPROACH TO THE IDENTIFIABLE PARAMETERS OF A MANIPULATOR
(1994-10-01)
LIN, SK
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
;
Institute of Electrical and Control Engineering
This article deals with the minimal parameters of a manipulator in the least squares sense, so that the minimal parameters are equivalent to the identifiable parameters. The least squares concept is used to introduce terminology for the minimal linear combinations (MLCs) of the system parameters that define a set of linear combinations of the system parameters. The number of elements of the set is minimal, vet the set still completely determines the system. Furthermore, it is shown that the problem of finding a set of MLCs of a manipulator can be simplified to that of finding two individual sets of MLCs that determine the entries of the inertia matrix and the gravity load. Although the approach is applied to the inertia constants of composite bodies to obtain a set of MLCs identical to an earlier one, the result is newly interpreted in the least squares sense. The approach itself is a new method for finding the identifiable parameters of a manipulator, and it yields some new insight into the manipulator dynamics. The crucial feature is that a set of MLCs found by using the present approach is guaranteed to be identifiable. The earlier approaches always require an identification method to verify the results. An equivalence theorem is also presented that rigorously states the equivalence between the different sets of minimal parameters. (C) 1994 John Wiley & Sons, Inc.
AN IDENTIFICATION METHOD FOR ESTIMATING THE INERTIA PARAMETERS OF A MANIPULATOR
(1992-06-01)
LIN, SK
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
;
Institute of Electrical and Control Engineering
This article presents an off-line identification method to estimate the minimal knowledge of the inertia parameters for determining the dynamic model of a manipulator. A new approach is proposed to find a set of the minimal knowledge of the inertia parameters. This set is recursively estimated by moving one joint at a time. The off-line identification procedure also provides a sufficient condition for a persistently exciting trajectory. A simulation example of Stanford arm illustrates the validity and simplicity of the identification procedure.
COMPUTATION OF INPUT GENERALIZED FORCES FOR ROBOTS WITH CLOSED KINEMATIC CHAIN MECHANISM - COMMENT
(1990-04-01)
LIN, SK
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
;
Institute of Electrical and Control Engineering
ESTIMATING MINIMAL PARAMETERS OF A MANIPULATOR FOR GRAVITY LOAD AND FRICTION
(1994)
LIN, SK
;
電控工程研究所
;
Institute of Electrical and Control Engineering
IDENTIFICATION OF A CLASS OF NONLINEAR DETERMINISTIC SYSTEMS WITH APPLICATION TO MANIPULATORS
(1994-09-01)
LIN, SK
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
;
Institute of Electrical and Control Engineering
This note presents a recursive identification method to estimate the minimal parameters of a class of nonlinear deterministic system. The result can be applied to a manipulator with unknown torque constants. A procedure to identify the torque constants, the friction, and the gravity parameters at the same time is then proposed. This is worthwhile since the PD feedback control with the gravity and friction compensation ensures a zero steady-state response for the set-point control. A theory addresses the minimal parameters composed of the three groups of parameters. The identification procedure for the minimal parameters is conducted by moving one joint with a constant velocity at a time. The persistently exciting trajectories for the identification are also suggested. The experiment on the PUMA 560 illustrates the identification method.
IMPLEMENTATION OF DAMPED RESOLVED ACCELERATION CONTROL FOR A MANIPULATOR NEAR SINGULARITY
(1995-08-01)
LIN, SK
;
WU, SL
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
Resolved acceleration control fails in the neighbourhood of the singularity of the Jacobian matrix. The damped least-squares method has been proposed to overcome this singularity problem. In earlier work, all components of the velocity of the end-effector were damped when a manipulator was near a singular point, so that some components of the velocity that are physically feasible were also damped, sacrificing accuracy. This paper presents a new approach that applies the damped least-squares method only to the degenerated directions since only the components of the velocity in the degenerated directions are inherently impossible to generate. This approach requires few computations and then can be implemented in real-time. Another feature is that the selection of the damping factor is a one-dimensional problem. The new damped resolved acceleration control scheme is implemented on the Puma 560 robot. The experiment results show the validity and the drawbacks of the damped resolved acceleration control in the neighbourhood of singular points.
IMPLEMENTATION OF DAMPED RESOLVED ACCELERATION CONTROL FOR A MANIPULATOR NEAR SINGULARITY
(1995-08-01)
LIN, SK
;
WU, SL
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Resolved acceleration control fails in the neighbourhood of the singularity of the Jacobian matrix. The damped least-squares method has been proposed to overcome this singularity problem. In earlier work, all components of the velocity of the end-effector were damped when a manipulator was near a singular point, so that some components of the velocity that are physically feasible were also damped, sacrificing accuracy. This paper presents a new approach that applies the damped least-squares method only to the degenerated directions since only the components of the velocity in the degenerated directions are inherently impossible to generate. This approach requires few computations and then can be implemented in real-time. Another feature is that the selection of the damping factor is a one-dimensional problem. The new damped resolved acceleration control scheme is implemented on the Puma 560 robot. The experiment results show the validity and the drawbacks of the damped resolved acceleration control in the neighbourhood of singular points.
MINIMAL LINEAR-COMBINATIONS OF THE INERTIA PARAMETERS OF A MANIPULATOR
(1995-06-01)
LIN, SK
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper deals with the problem of identifying the inertia parameters of a manipulator, We begin by introducing the terminology of minimal linear combinations of the inertia parameters (MLC's) that are linearly independent of one another and determine the manipulator dynamics while keeping the number of linear combinations of the inertia parameters to a minimum, The problem is then to find an identification procedure for estimating the MLC's and to use the MLC's in the inverse dynamics for control. The recursive Newton-Euler formulation is rederived in terms of the MLC's. The resulting formulation is almost as efficient as the most efficient formulation in the literature. This formulation also provides a starting point from which to derive a recursive identification procedure, The identification procedure is simple and efficient, since it does not require symbolic closed-form equations and it has a recursive structure. The three themes concerning the dynamic modeling of a manipulator-the MLC's, the inverse dynamics in terms of the MLC's, and the identification procedure-are treated in sequence in this paper.