Mechanical (direct-drive) systems designed for high-speed and high-accuracy applications require control systems that eliminate the influence of disturbances like cogging forces and friction. One way to achieve additional disturbance rejection is to extend the usual (P(I)D) controller with a disturbance observer. There are two distinct ways to design, represent, and implement a disturbance observer, but in this paper it is shown that the one is a generalization of the other. A general systematic design procedure for disturbance observers that incorporates stability requirements is given. Furthermore, it is shown that a disturbance observer can be transformed into a classical feedback structure, enabling numerous well-known tools to be used for the design and analysis of disturbance observers. Using this feedback interpretation of disturbance observers, it will be shown that a disturbance observer based robot tracking controller can be constructed that is equivalent to a passivity based controller. By this equivalence not only stability proofs of the disturbance observer based controller are obtained, but it also provides more transparent controller parameter selection rules for the passivity based controller.

Issue Section:
Technical Papers
Keywords:
manipulator dynamics, stability, observers, three-term control, Observers, Mechanical System, Design, Unknown Input Observer, Passivity Based, Tracking, Manipulators
Topics:
Control equipment, Design, Feedback, Stability, Robots, Filters
1.
Johnson
,
C.
,
1971
, “
Accommodation of External Disturbances in Linear Regulator and Servomechanism Problems
,”
IEEE Trans. Autom. Control
,
16
(
6
), pp.
635
–
644
.
2.
Profeta
,
J.
,
Vogt
,
W.
, and
Mickle
,
M.
,
1990
, “
Disturbance Estimation and Compensation in Linear Systems
,”
IEEE Trans. Aerosp. Electron. Syst.
,
26
(
2
), pp.
225
–
231
.
3.
Coelingh, H., Schrijver, E., De Vries, T., and Van Dijk, J., 2000, “Design of Disturbance Observers for the Compensation of Low-Frequency Disturbances,” Proc. of Int. Conf. Motion and Vibration Control (MOVIC) 2000, Sydney, Australia, B. Samali (ed.), pp. 75–80.
4.
Murakami, T., and Ohnishi, K., 1990, “Advanced Motion Control in Mechatronics—A Tutorial,” Special Lecture—Proc. of IEEE Int. Workshop on Intelligent Control, Istanbul, Turkey, 1, pp. SL9–SL17.
5.
Umeno
,
T.
, and
Hori
,
Y.
,
1991
, “
Robust Speed Control of DC Servomotors Using Modern Two Degrees-of-Freedom Controller Design
,”
IEEE Trans. Ind. Electron.
,
38
, pp.
363
–
368
.
6.
Lee
,
H.
, and
Tomizuka
,
M.
,
1996
, “
Robust Motion Controller Design for High-Accuracy Positioning Systems
,”
IEEE Trans. Ind. Electron.
,
43
, pp.
48
–
55
.
7.
Mita
,
T.
,
Hirata
,
M.
,
Murata
,
K.
, and
Zhang
,
H.
,
1998
, “
h∞ Control Versus Disturbance-Observer-Based Control
,”
IEEE Trans. Ind. Electron.
,
45
(
3
), pp.
488
–
495
.
8.
Bickel
,
R.
, and
Tomizuka
,
M.
,
1999
, “
Passivity-Based Versus Disturbance Observer Based Robot Control: Equivalence and Stability
,”
ASME J. Dyn. Syst., Meas., Control
,
121
, pp.
41
–
47
.
9.
Ko, R., Halgamuge, S., and Good, M., 1998, “An Improved Feedforward Extension and Disturbance Observer Design in High-Speed and High-Precision Tracking Control,” Proc. of Int. Conf. Motion and Vibration Control (MOVIC), Zu¨rich, Switzerland, 2, pp. 745–750.
10.
Kempf, C., and Kobayashi, S., 1996, “Discrete-Time Disturbance Observer Design for Systems With Time Delay,” Proc. of Int. Workshop on Advanced Motion Control, 1, pp. 332–337.
11.
Endo
,
S.
,
Kobayashi
,
H.
,
Kempf
,
C.
,
Kobayashi
,
S.
,
Tomizuka
,
M.
, and
Hori
,
Y.
,
1996
, “
Robust Digital Tracking Controller Design for High-Speed Positioning Systems
,”
Control Eng. Pract.
,
4
(
4
), pp.
527
–
536
.
12.
Tesfaye
,
A.
,
Lee
,
H.
, and
Tomizuka
,
M.
,
2000
, “
A Sensitivity Optimization Approach to Design of a Disturbance Observer in Digital Motion Control Systems
,”
IEEE/ASME Trans. Mechatronics
,
5
(
1
), pp.
32
–
38
.
13.
Hori, Y., Shimura, K., and Tomizuka, M., 1992, “Position/Force Control of Multi-Axis Manipulator Based on the TDOF Robust Servo Controller for Each Joint,” Proc. of American Control Conf., 1, pp. 753–757.
14.
Doyle, J., Francis, B., and Tannenbaum, A., 1992, Feedback Control Theory, McMillam, New York.
15.
Kempf
,
C.
, and
Kobayashi
,
S.
,
1999
, “
Disturbance Observer and Feedforward Design for a High-Speed Direct-Drive Positioning Table
,”
IEEE Trans. Control Syst. Technol.
,
7
(
5
), pp.
513
–
526
.
16.
Francis
,
B.
, and
Wonham
,
W.
,
1976
, “
The Internal Model Principle of Control Theory
,”
Automatica
,
12
, pp.
457
–
465
.
17.
Johnson, C., 1976, Theory of Disturbance-Accommodating Controllers, Control and Dynamic Systems, Vol. 12, pp. 387–489.
18.
Hostetter
,
G.
, and
Meditch
,
J.
,
1973
, “
On the Generalization of Observers to Systems With Unmeasurable, Unknown Inputs
,”
Automatica
,
9
, pp.
721
–
724
.
19.
Franklin, G., Powell, J., and Emani-Naeini, A., 1994, Feedback Control of Dynamic Systems, Addison Wesley.
20.
Benschop, R., Steinbuch, M., and Bosgra, O., 1995, “Observer for Unknown Inputs and Disturbances: A Survey of Literature,” Nat. Lab. Unclassified Report (RWR-501-RB-95015-rb).
21.
Sadegh
,
N.
, and
Horowitz
,
R.
,
1990
, “
Stability and Robustness Analysis of a Class of Adaptive Controllers for Robotic Manipulators
,”
Int. J. Robot. Res.
,
9
(
3
), pp.
74
–
92
.
22.
Slotine
,
J.
, and
Li
,
W.
,
1987
, “
On the Adaptive Control of Robot Manipulators
,”
Int. J. Robot. Res.
,
6
(
3
), pp.
44
–
59
.
23.
Ortega
,
R.
, and
Spong
,
M.
,
1989
, “
Adaptive Motion Control of Rigid Robots: A Tutorial
,”
Automatica
,
25
(
6
), pp.
877
–
888
.
Copyright © 2002
 by ASME
You do not currently have access to this content.