Design and development of a new piezoelectric linear Inchworm® actuator

This paper presents a proof-of-concept design of an inchworm-type piezoelectric actuator of large displacement and force (or power) for shape control and vibration control of adaptive truss structures. Applications for such actuators include smart or adaptive structural systems, auto and aerospace industries. The proposed inchworm-type actuator consists of three main components with frictional clamping mechanisms: two clamping or braking devices and one expanding device. The two frictional clamping devices provide alternating braking forces when the moving shaft, which is pushed by expanding device, walks inside the PZT tubular stack and emulates an inchworm, summing small steps to achieve large displacements. Since the development of a robust clamping mechanism is essential to realize the high force capability, a considerable design effort has been focused on optimizing the clamping device to increase the output force. CATIA is used as a platform to model the whole actuator and ANSYS is used to analyze and optimize the performance of the actuator. The proposed design avoids the tight tolerance of the tube diameters and reduces the clearance between clamps and the moving shaft with the adjustment device. The moving shaft of the actuator could also be replaced by one member of a truss structure for vibration suppression and position control purposes. In the proposed actuator the flexure clamps can also be easily replaced to outfit different dynamic characteristics. The complete design of the proposed actuator has been performed using the finite element analysis. The simulation result confirms that the output force of 160 N and incremental displacement in each step of 8.3 μm can be achieved using the proposed actuator. A prototype of actuator has been fabricated and static tests have been performed to validate the simulation results.