This paper presents analysis of a particular force tracking control problem for rectilinear hydraulic actuators governed by a servovalve. It presents no new theory, but rather uses a revealing model reduction insight coupled with Classical analysis to explain a physical phenomenon. As such, this work is an attempt to explain why a seemingly innocuous problem is more subtle than initially believed. A motivation for this problem is given along with prior attempts at a simple solution. It is shown that simple controller solutions are quite adequate for other types of control objectives such as force regulation or position tracking. However, most simple solution methods are shown to be inadequate for force tracking due to fundamental limitations of the problem formulation. Due to an inherent feedback mechanism, the poles of the plant being forced by the hydraulic actuator become zeros of the open loop force transfer function. Therefore, more advanced control algorithms are shown to be a necessity rather than a luxury.

1.
Alleyne, A., 1994, “Nonlinear and Adaptive Control of Active Suspensions,” Ph.D. dissertation, University of California, Berkeley.
2.
Alleyne, A., 1996, “Nonlinear Force Control of an Electro-Hydraulic Actuator,” Proceedings of the 1996 Japan/USA Symposium on Flexible Automation, pp. 193–200, Boston, MA, June.
3.
Alleyne
A.
, and
Hedrick
J. K.
,
1995
, “
Nonlinear Adaptive Control of Active Suspensions
,”
IEEE Transactions on Control Systems Technology
, Vol.
3
, No.
1
, Mar., pp.
94
102
.
4.
Armstrong-Helouvry
B.
,
Dupont
P.
, and
Canudas de Wit
C.
,
1994
, “
Friction in servo machines: Analysis and control methods
,”
Applied Mechanics Reviews
, Vol.
47
, No.
7
, pp.
275
305
, July.
5.
Dyke
S. J.
,
Spencer
B. F.
,
Quast
P.
, and
Sain
M. K.
,
1995
, “
Role of Control-Structure Interaction in Protective System Design
,”
Journal of Engineering Mechanics
, ASCE, Vol.
121
, No.
2
, pp.
322
338
, Feb.
6.
Hrovat
D.
,
1997
, “
Survey of Advanced Suspension Developments and Related Optimal Control Applications
,”
Automatica
, Vol.
33
, No.
10
, pp.
1781
1817
.
7.
Lee
S. R.
, and
Srinivasan
K.
,
1991
, “
Self-Tuning Control Application to Closed-Loop Servo-Hydraulic Material Testing
,”
ASME JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL
, Vol.
112
, No.
4
, pp.
680
689
, Dec.
8.
Liu, R., 1998, “Nonlinear Control of Electrohydraulic Servosystems: Theory and Experiment,” M. S. thesis, Dept. of Mech. & Ind. Eng., Univ. of Illinois, Urbana-Champaign, Sept.
9.
Patarinski
S.
, and
Botev
R.
,
1993
, “
Robot Force Control, a Review
,”
Mechatronics
, Vol.
3
, No.
4
, pp.
377
398
.
10.
Thompson
A. G.
, and
Chaplin
P. M.
,
1996
, “
Force Control in Electrohydraulic Active Suspensions
,”
Vehicle System Dynamics
, Vol.
25
, pp.
185
202
.
11.
Ulsoy, G., 1997, Personal Communication, Seattle, WA, Jan.
12.
Vossoughi
R.
, and
Donath
M.
,
1995
, “
Dynamic Feedback Linearization for Electro-hydraulically Actuated Control Systems
,”
ASME JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL
, Vol.
117
, No.
4
, pp.
468
477
, Dec.
13.
Yi
K.
, and
Hedrick
J. K.
,
1995
, “
Observer-Based Identification of Nonlinear System Parameters
,”
ASME JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL
, Vol.
117
, No.
2
, pp.
175
182
, June.
14.
Yue
C.
,
Butsuen
T.
, and
Hedrick
J. K.
,
1989
, “
Alternative Control Laws for Automotive Active Suspensions
,”
ASME JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL
, Vol.
111
, pp.
286
291
, June.
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