Optimal Low-Power Piezoelectric Actuator Control With Charge Recovery for a Microrobotic Leg

This paper describes an efficient control strategy for a piezoelectric microactuator using charge recovery. For piezoelectric actuators, as well as other actuators that behave primarily as capacitive loads, energy consumption can be reduced by minimizing the number of times an actuator is charged and by recovering stored energy when it is turned off. An integer programming-based algorithm is used to drive microrobotic legs powered by piezoelectric actuators to a specified angle in a specified time using minimum energy. Partial charge recovery is incorporated; this allows the use of a more flexible controller than a pure on-off controller, with two or more intermediate voltage levels between the minimum and maximum voltages available to improve positioning accuracy. Simulated and experimental tests show that a prototype piezoelectric robotic leg joint achieved controlled movements with one third of the energy consumed by a pure on-off controller.