Optimal on-off controller with charge recovery for thin-film piezoelectric actuators for an autonomous mobile micro-robot

In this paper an efficient control strategy using charge recovery for a MEMS piezoelectric actuator is described. For piezoelectric actuators or other actuation schemes which act as capacitor loads, energy consumption can be reduced by minimizing the number of times the actuator is charged and by recovering the drained energy when it is turned off. An integer programming-based algorithm is used to drive micro-robotic legs consisting of piezoelectric actuators to a certain specific angle in a given time with the use of minimum energy. Partial charge recovery, which recovers a portion of the drained energy, is incorporated by making use of a lighter inductor. This allows the use of a more flexible controller than a pure ultra low-power on-off controller, with two or more intermediate voltage levels between the minimum and maximum voltages available to improve positioning accuracy, while also reducing energy consumption.