The performance of the Conventional On-Off Controller with deadband was improved by applying the Modified On-Off Controller with fixed pulse width for an electro-pneumatic on-off servo mechanism, with only position feedback. While it can be cheaply implemented, and effectively improve the steady state error, it has the drawback such as longer rise time than the Conventional On-Off Controller.
In this thesis, another Modified On-Off Controller is developed to improve the rise time, called Modified On-Off Controller with varying pulse width. Comparing to the Modified On-Off Controller with fixed pulse width, this controller generates pulses of which the pulse width increases linearly as the error increases between deadband and pulseband. To investigate the performance of this control configuration a series of experiments are conducted for the various controller parameters, which include the deadband, pulseband, pulse frequency and etc.. The experimental results show that the Modified On-Off Control technique with varying pulse width reduces the minimum stable deadband slightly, and also decreases the rise time, comparing to the Modified On-Off Control technique with fixed pulse width.
The PWM Control technique is applied to eliminate steady state error, with various controller parameters-such as, pulse frequency, integral gain and etc.. The position control for this case is experimented by applying only proportional controller. The experimental results show that the rise time increases, but the steady state error is almost zero. And, the tracking control is experimented by applying proportional and proportional-integral controller. The experimental results show that the proper integral gain makes the steady state error almost zero.
