A New Velocity Estimator for Motion Control Systems

In motion control systems, differentiated position signal is commonly used to estimate velocity, and used for speed feedback control. Position quantization error can result in the amount of noise jamming, which affects system control precision and stability. In this paper, a simple but reliable velocity estimator is proposed to estimate velocity from the measured position. This estimator consists of two parts: a traditional moving-average filter for data smoothing process, and a closed-loop PID controller to compensate the phase lag caused by smoothing process. Simulation and experimental results demonstrate that the quantization error in the velocity feedback signal can be reduced dramatically when the proposed estimator is used for velocity estimation, the estimated signal has fewer phase lag than the traditional velocity estimation method, and the current noise of motor is reduced as well.