A practical control strategy for servo-pneumatic actuator systems

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.