Combined Velocity and Disturbance Observer for Cost-Sensitive Motor Control Applications

Many cost-sensitive motor control applications use position sensors with limited resolution due to budget constraints. For such applications, positioning performance reaches a critical point at low operating velocities, where the effects of quantization noise in velocity measurement and mechanical disturbances such as cogging torque become more prominent. Increasing the mechanical loop sampling frequency can improve the system's dynamic response but leads to noisier current commands due to exacerbated velocity quantization. Increasing controller gains has similar effects and downsides. The proposed combined velocity and disturbance observer addresses such challenges for low-cost motor control applications by improving velocity resolution through estimation and simultaneously identifying and compensating unwanted mechanical disturbances.