Harmonic PZT poly-actuators

Capacitive actuators, such as piezoelectric stack actuators, provide an efficient solution for robotic and mecha-tronic systems that typically require large forces and minimal velocities over long periods of time. To overcome the stack actuator's limitations, particularly their limited stroke, a harmonic poly-actuator design is presented. This design utilizes a multitude of intermediate buckling amplification mechanisms in a parallel arrangement to create a large stroke, high force actuator. The redundant system architecture combined with a particular spatial and temporal coordination allow for a number of salient features, including robustness to failure, backdrivability, and continuous force control via elementary ON-OFF control. A prototype was built using six intermediate buckling amplification mechanisms and was able to produce over 100 Newtons of force over a stroke of 450 mm.