Position Tracking Control with Velocity from Accelerometer and Encoder

Being widely used in industrial systems and manufacturing lines, precision position control systems need to use high feedback control gains to reject disturbances. However, phase-lag in velocity estimation resulting from encoder measurement imposes a limitation on maximum allowable feedback gains, when system stability and control smoothness are concerned. In this paper, use of velocities derived from both acceleration and position measurements is suggested. The derived velocity possesses a much higher bandwidth without having theoretical phase-lag. Experimental results reveal that the use of velocities derived from practical accelerometers and encoders allows a typical position control system to substantially increase its feedback gains without compromising stability and control smoothness. It in turn results in much smaller tracking errors, compared to scenarios when velocities are created from position sensors only.