A practical control strategy with a simple controller structure is proposed
for servo-pneumatic cylinder actuator systems. Theoretical analysis reveal
s that the acceleration of the piston indirectly represents the cylinder ch
amber pressure difference so it is possible to employ acceleration feedback
instead of pressure feedback in the construction of servo-pneumatic actuat
or control systems. The main features of the control strategy developed in
the paper are (1) using acceleration feedback to improve the stability of t
he system; and (2) introducing time-delay minimisation and optimised null o
ffset compensation to address the problem of time delay and dead zone, whic
h are mainly caused by the compressibility of air and friction. The experim
ental studies have been conducted using an asymmetric pneumatic cylinder sy
stem and the results show that the system performance has been much improve
d when compared with a conventional PID controller. (C) 1999 Elsevier Scien
ce Ltd. All rights reserved.