INVESTIGATION OF INFLUENCES OF FABRICATION TOLERANCES ON OPERATIONAL CHARACTERISTICS OF PIEZO-ACTUATED STICK-SLIP MICRO-DRIVES

Piezo-actuated stick-slip micro-drives (PASSMDs) are often used in microrobotic applications due to their advantages of a straightforward design and good operational characteristics. In this work, influences of fabrication tolerances on operational characteristics of PASSMDs are theoretically investigated. A dynamic model describing the whole macroscopic movement of the driver’s runner and the actuators, and the microscopic behavior of the frictional contacts using the method of dimensionality reduction, was used. Three essential parameters of the drives including the angle between working surfaces of the runner, the alignment angle between two actuator blocks on each side of the runner, and the stiffness of an individual actuator, whose values are impacted by the tolerance of the fabrication and assembly process, were considered as the input of the investigation. By performing hybrid-dynamic simulations, influences of these parameters on the drives' operational characteristics, including the repeatability of the step length, the critical amplitude phenomenon, and the maximal-achievable driving frequency/velocity, were evaluated. Simulation results show that these parameters significantly influence on the characteristics of the drives. The contribution of this work is so important that several important phenomena of PASSMDs, which are experimentally detected, are physically explained for the first time. The results of this work could help designers to optimize for better generations of PASSMDs.