Improved Servomechanism Control Design - Nonswitching Case

This paper attempts to achieve time-optimal performance for servomechanisms via a practical feedback control law. An improvement over the traditional Proximate Time Optimal Servomechanism (PTOS) is proposed in order to eliminate the conservatism present in the controller. The original PTOS switches from the nonlinear approximation of Time Optimal Control (TOC) to a linear controller as the system approaches the reference point. This switching results in a compromise in performance inasmuch as the linear controller is not sufficiently aggressive to settle the system output with acceptable levels of overshoot. The proposed controller eliminates the necessity of the switching function by making use of an elaborate nonlinear control law. Simulations and experimental results show that the proposed design achieves levels of performance comparable to that of the theoretical TOC.