Design and evaluation of linear ultrasonic motors for a cardiac compression assist device

Exploiting new suitable actuators is key in developing cardiac compression assist devices. In this paper, a self-moving linear ultrasonic motor with large displacement within a limited housing space is proposed and investigated as a primary attempt to develop a new actuator suitable for a cardiac compression assist device. In the motor, the rectangular piezoelectric ceramic plates are directly used as the vibrators of a self-moving element with just one input power. The housing is used directly as a guide. Reversible motion direction is achieved through applying power to different electrodes. The motion principle is analysed on the basis of harmonic response calculation results. Using a data acquisition board with LabVIEW software, a control circuit, a laser displacement sensor, a force sensor, and a spring, an experimental rig is set up. Measured resonant frequencies and frequency properties agree with the calculated results and their analysis. Also under force control of the linear ultrasonic motor, 1 Hz pulse of desired force is realised with thrust force changing from 0 to 68% of the desired force in about 100 ms after 8 mm of displacement.