Chaos of a pneumatic actuator in digital control

This paper describes chaotic motion and control of a pneumatic actuator in digital control. Experiments are carried out in order to investigate the conditions in which chaotic motion is generated. A strange vibration appears when the system is in a transition from stable to unstable with a proportional digital controller. It is confirmed that the strange vibration is chaotic from 3 indexes, i.e., the auto-correlation function, the power spectrum and Lyapunov exponents. Computer simulations also carried out in order to clarify the cause of this generated chaotic motion. As a result of the computer simulations, it can said that the friction, feedback interval and the gain of the control system are very important in generating the chaotic motion. Finally, OGY control method, which is called the method for controlling chaos, is applied. The experiment shows the OGY control method is very useful in keeping the chaotic vibration stable