抄録
This paper presents a method for self-adjusting the parameters of a control system using a sinusoidal test signal. In this method, the frequency of the test signal is automatically adjusted to have 180° phase lag in the control loop, and the proportional sensitivity of the controller is adjusted to keep the gain of the test signal constant at this frequency. The integral and derivative time of the controller are also adjusted to have a fixed relation to this frequency.
This system has two self-adjusting loops, each for adjusting frequency of the test signal and for adjusting proportional sensitivity of the controller. The dynamic behaviors of these loops are equivalent to that of the first order lag system, and the increase in the speed of response of the loop is obtained by increasing the amplitude of the test signal.
The dynamic error in the parameter adjustment in this system depends on the spectral density of the process noise at the frequency of the test signal. For detecting the signal component in the control system output which contains the signal and noise, a simple demodulation technique which cross-correlate the sign of this output with a known sinusoidal signal, is proposed in this paper. It is shown that by the introduction of this technique, the dynamic characteristics of the self-adjusting loops are improved.
Experimental results of this method applied to a flow control system are also shown.
