A Large-stroke Motion Controller for Speed-constrained Servo Systems

A modified design of expanded proximate time-optimal servo (PTOS) controller is proposed for typical servo systems characterized by an integrator cascaded with a damping block. The controller resorts to the time-optimal control for initial acceleration, and then switches into a linear control law to achieve a smooth settling. In the presence of speed constraint, a speed regulation stage is inserted in the tracking process. Thus the controller can accomplish large-stroke motion in speed-constrained servo systems. To tackle the unmeasured-speed and unknown disturbance, an extended state observer (ESO) can be included in the controller. The controller is applied to a permanent magnet DC servo system for position control. MATLAB simulation and experimental verification using a TMS320F28335 board are conducted. The results confirm that the proposed controller can track a wide range of target references with desirable performance under speed constraint and load disturbance.