Low Speed Control of PMAC Servo System Based on Reduced-order Observer

Incremental encoders are popular for detecting angular position and speed. However, the conventional incremental encoder-based methods for estimating speed are prone to poor performance at low speed where the encoder output rate is correspondingly low, leading to a number of research efforts in improved low-speed detection algorithms. To improve speed control performance, a speed detection method based on reduced-order observer is presented in this paper. The observer can interpolate speed and position which is the integration of speed and compared with real data from the encoder when the encoder pulse is detected between encoder pulses. Furthermore, inertia identification based on recursive extended least square algorithm is presented to reduce sensitivity of the speed estimation. Experimental results show that low speed control performance using the reduced-order order is superior to that of conventional one