A jerk-constrained time-optimal servo with disturbance compensation

• Derivation regarding the jerk-constrained time-optimal control (JCTOC) system is provided.
• The JCTOC system has increased robustness with the addition of a disturbance observer.
• An enhanced disturbance observer is proposed and experimentally proved effective.
• In practice JCTOC outperforms the PD control in terms of settling time and maximum control effort.

For positioning servo-systems, this paper presents a jerk-constrained time- optimal control (JCTOC) scheme, augmented with an improved disturbance rejection method. In mechanical systems, the jerk that is the time derivative of acceleration may cause many unwanted results when too high. Thus, the JCTOC method is proposed to constrain the system׳s jerk and also obtain a time-optimal characteristic with the constrained jerk. However, because the JCTOC relies on the accuracy of the plant׳s model, system uncertainties and disturbances can adversely affect the output response. Thus, a disturbance observer (DOB) is added for compensation of the perturbation. The DOB used in this paper is in an integral form, and is thus referred to as an integral DOB (IDOB). The IDOB is further enhanced with a dynamic compensator to provide both better noise immunity and asymptotic compensation for disturbances of various orders.