Matlab Based Interactive Model of a Position Servo Drive*

An interactive MATLAB based simulation tool is presented that may be used for verifying properties of several position control loops for electrical drives with a torque generator and position measurement by an incremental position sensor. The compared loops include cascade P-PI control with P controller in a position loop and PI controller in an underlying velocity loop, its filtered versions denoted as P-FPI and FP-FPI controls, and the solution with PD controller and disturbance observer (DO) using low pass filters in the disturbance observer and in the position feedback (DO-FPID). All controls may be supplemented by a feedforward to eliminate the error if a setpoint signal is continuous. As a default option the tool provides parameter tuning of all position controllers for a nearly equal integral of absolute error (IAE) of setpoint steps. Differences in the noise impact are highlighted by relative total variance of the input and output signals. The tool enables users an experimental way of discovering properties of particular loops. It exhibits high importance of appropriate filter design and shows that the solutions with the feedback filters may yield for both the nominal and uncertain situations the highest performance to noise impact (torque ripple) ratio.