A Comparative Assessment of Electronic and Pneumatic Controllers When Controlling Fast Processes Subject to Rapid Load Disturbance

Abstract

Experimental and analytical methods have been developed for measuring the performance, in an integral-square-error sense, of process control systems subject to random load disturbances. Results are given for the relative performance of pneumatic and electronic controllers when controlling a fast process (process time constant 1.3 s) subject to rapid load disturbances. It is shown that the performance of both types of controller is essentially the same when short lengths of pneumatic transmission line are used, but the performance of the pneumatic controller considerably deteriorates when longer transmission lines are used. The analytical method of performance assessment can give accurate information on controllability at the process design stage, provided that the process is linear about its operating point and that the transfer function is known.