Design and performance of a resonant roller wedge actuator

A compact rotary motor driven by piezoelectric bimorph actuators was developed for applications in adaptive, conformable structures for flow control. Using a roller wedge (rotary roller clutch) as its central motion rectifying element, the actuator converts electrical power to mechanical power by way of a set of resonating bimorph/mass systems. With this type of resonant drive system, the output mechanical power of the actuator was dramatically improved over previous inchworm-type designs. Also, the actuator cost was kept low by using commercial roller clutches and bimorph actuators instead of PZT stacks. Within an application size constraint of 4 × 4 × 1.75 inches, the unloaded speed was 600 RPM, the stall torque was 0.5 N-m, and the peak output power was nearly 4 watts. The motor is driven by a single frequency sinusoidal input, resulting in significant improvements of the cost, size and complexity over typical piezoelectric actuator drivers. Since the backlash of the roller clutch is a critical parameter in assessing the motor performance, an experimental study was performed to better understand its dynamics.