A Novel Four legged linear piezoelectric inchworm motor with high thrust force

Abstract

A major limitation of most linear motors is limited travel range and low load capacity. In this research, a large motion range piezoelectric Inchworm Motor (IM) is realised which not only harnesses the prominent advantages of piezo-actuator but the four-legged design simultaneously offers reliable self-locking capability in a compact form-factor. The displacement deformation of each element of the motor (clamps, extender) is determined using finite element analysis (FEA) through force distribution analysis. Appropriate clamping force adjustment method on the rail/stator of the motor is adopted using load cell followed by multiple linear regression modelling to dynamically consider the clamping force and inherent non-linearities of piezo-actuators (PAs). The hardware prototype is fabricated and the experiment results verify the validity of the data driven model. Clamping error analysis, step length dependent stability profile and dynamic driving force has been carried out to characterize the IM. Performance evaluation of the motor has been researched at different voltages, frequencies and loads to assess its operating profile. Mechanical output suggests that the prototype achieves a maximum no load speed of 39.64 mm/sec under clamping force of 2 N at 100 V and frequency of 2000 Hz with 30% duty cycle. With load of 700 g, 0.46 mm/sec speed is obtained under a clamping force of 8 N. In addition, bidirectional control signal mechanism for the IM has been also developed, tested and implemented in real-time environment. The proposed large driving force prototype designed is highly suitable for industrial linear translation systems requiring high resolution, large strokes, and heavy loads capacities.