Deog-Ho Lee, Seok-Kyoon Kim, and Kyo-Beum Lee, "Nonlinear Output-Feedback Speed Servo Systems through Active Damping Injection and Position Filtering Approaches without Current Feedback," Journal of Power Electronics, vol. 22, pp. 1199-1208, Jul. 2022. -S > Paper

This paper proposes a novel current feedback-free speed regulation method for servo systems subject to system parameter and load uncertainties. The proposed solution has two features. First, the position measurement from the rotary encoder constitutes the speed and acceleration estimates for control loops through the

position filter with nonlinearly-structured design parameters and without any dependence on the system parameters. Second, the proposed controller requires only nominal system parameter information and stabilizes both the speed and acceleration loops using only the position measurement by injecting active damping terms, which leads to pole-zero cancellation. A prototype servo system built using a 500 W brushless DC-motor-based dynamo experimentally validates the effectiveness of the proposed solution in speed tracking and regulation tasks.