Second-Order Order-Reduction Speed and Acceleration Estimators for Speed Servo Systems via Model-Free Adaptive Observer Design Technique

The proposed model-free adaptive observer estimates the speed, acceleration, and low-frequency disturbance for servo drives based on a second-order order-reduction technique, which ensures consistent dynamic performance and is independent of the servo system model and load information. The contributions of this article are twofold: 1) the combination of a coordinate transformation and special gain structure diagonalizes the observation error dynamics to render the performance tuning process more convenient; and 2) an extra adaptation mechanism estimates the low-frequency disturbance to improve the closed-loop robustness according to the output filtering error. A 500-W prototype servo drive validates the effectiveness of the proposed estimation technique by incorporating a feedback system application.