Development of a novel self-locking-at-rest piezoelectric inchworm motor with high switching frequency driving ability

In this paper, a novel piezoelectric actuator-based inchworm motor and its driving mechanism has been proposed for high speed linear application. Three high voltage positive square pulses with appropriate phase sequence amongst them have been applied to the two clamps and one extender of IM to achieve the desired linear translation. Isolated mosfet-based switching and oscillation circuits have been designed to operate the motor at high switching frequencies by dynamically reducing the capacitive reactance of the piezoelectric stack actuators. Consequently, experiments on the characterization of the piezo-actuators have been performed to identify the pre stress on the motor rail. Geometric model of the system has been developed using finite element analysis to determine displacement distribution in Clamping Mechanism and Extending Mechanism before physically fabricating the motor prototype to verify the driving mechanism. Performance evaluation has been carried out under varying duty cycles, switching frequencies and loads. The motor is observed to achieve a maximum no load speed of 60 mm/s under the 80-90 V positive square pulse at a frequency of 3 kHz with a 20 % duty cycle. A relatively high electrical driver efficiency of 42 % is experimentally achieved which makes the proposed mechatronic system highly suitable for low-size, high torque industrial applications.