This paper presents a robust controller for tracking control of a direct-drive robot. The proposed controller consists of two portions: a computed torque method which precompensates for dynamics of the modeled plant and an H∞ controller which postcompensates for residual errors which are not completely removed by the computed torque method. Experimental methods for identifying appropriate model structure and parameters are presented, and three specific controller types are compared. Using the robot designed in our laboratory, the combined controller reduced tracking errors by one half compared to computed torque control alone, and by one sixth compared to conventional independent joint control.

Issue Section:
Technical Papers
Topics:
Robots, Tracking control, Control equipment, Errors, Torque, Dynamics (Mechanics), Experimental methods, Torque control
1.
An, C. H., Atkenson, C. G., and Hollerbach, J. M., 1988, Model-Based Control of a Robot Manipulator, The MIT Press.
2.
Asada
H.
and
Kanade
T.
,
1983
, “
Design of Direct-Drive Mechanical Arms
,”
ASME Journal of Vibration, Acoustic, Stress, and Reliability in Design
, Vol.
105
(
3
): pp.
312
–
316
.
3.
Asada, H. and Youcef-Toumi, K., 1983, “Analysis and Design of Semi-Direct-Drive Robot Arms,” Proc. of American Control Conference, pp. 757–764, San Francisco.
4.
Asada
H.
and
Youcef-Toumi
K.
,
1984
, “
Analysis and Design of a Direct-Drive Arm with a Five-Bar Link Parallel Drive Mechanism
,”
ASME JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL
, Vol.
106
(
3
): pp.
225
–
230
.
5.
Craig, J. J., 1986, Introduction to Robotics—Mechanics & Control, Addison-Wesley.
6.
Doyle, J. C., et al., 1989, “State-Space Solution to Standard H2 and H∞ Control Problems,” IEEE Transactions on Automatic Control, Vol. 34, No. 8, Aug.
7.
Francis, B. A., 1987, A Course in H∞ Control Theory, Vol. 88 in Lecture Notes in Control and Information Science Series.
8.
Glover, K., and Doyle, J. C., 1988, “State Space Formulae for All Stabilizing Controllers that satisfy an H∞-norm Bound and Relations to Risk Sensitivity,” System and Control Letters.
9.
Isidori
A.
, and
Astolfi
A.
,
1992
, “
Disturbance Attenuation and H∞ Control via Measurement Feedback in Nonlinear System
,”
IEEE Transactions on Automatic Control
, Vol.
37
, pp.
1283
–
1293
.
10.
Khosla, P. K., and Kanade, T., 1986, “Experimental Evaluation of the Feedforward Compensation and Computed-Torque Control Schemes,” American Control Conference, June.
11.
Koivo
A. J.
, and
Guo
T. H.
,
1983
, “
Adaptive Linear Controller for Robotic Manipulators
,”
IEEE Trans. Automat. Contr.
, Vol.
AC-28
, pp.
162
–
171
.
12.
Lee
D. G.
,
Kim
K. S.
, and
Kwak
Y. K.
,
1990
, “
Manufacturing of a SCARA Type Direct-Drive Robot with Graphite Fiber Epoxy Composite Material
,”
Robotica
, Vol.
9
, pp.
219
–
229
.
13.
Luh
J. Y. S.
 et al.,
1980
, “
On-line Computational Scheme for Mechanical Manipulators
,”
ASME JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL
, Vol.
102
, pp.
69
–
76
, June.
14.
Maciejowski, J. M., 1989, Multivariable Feedback Design, Addison-Wesley.
15.
Miyamoto
 et al.,
1988
, “
Feedback-Error-Learning Neural Network for Trajectory Control of a Robotic Manipulator
,”
Neural Networks
, Vol.
1
, pp.
251
–
265
.
16.
Ozaki, T. et al., 1991, “Trajectory Control of Robotic Manipulators Using Neural Networks,” IEEE Trans. on Ind. Electronics, Vol. 38, No. 3, June.
17.
Schaft
V. D.
 et al.,
1992
, “
L2 Gain Analysis of Nonlinear Systems and Nonlinear State Feedback H∞ Control
,”
IEEE Transactions on Automatic Control
, Vol.
37
, pp.
770
–
784
.
18.
Slotine
J. E.
, and
Li
W.
,
1988
, “
Adaptive Manipulator Control: A Case Study
,”
IEEE Trans. Automat. Contr.
, Vol.
33
, No.
11
, pp.
995
–
1003
, Nov.
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