Mesoscale piezoelectrically driven mechanisms - design, modeling, fabrication, and control

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Mechanisms and robots remain difficult to fabricate and actuate at small scales. While these challenges have found suitable solutions in medium to large scale robotics, at the mesoscale, on the order of a millimeter to centimeters, these challenges remain. Piezoelectric materials represent one possible solution to the challenge of actuation as they are materials that strain when an electric field is applied across them. At small scales in particular, actuation via the piezoelectric effect becomes favourable. While generating only small displacements, these actuators have a large bandwidth and hence can generate fast and precise movements. This research program has three main objectives which are to leverage new fabrication techniques in order to create new piezoelectric motors and parallel robots that are piezoelectrically driven. The first objective is to find cost effective fabrication techniques for piezoelectrically driven structures. The second is to build from my recent work to create planar piezoelectric motors based on a series of unimorph arms. I have designed and fabricated a series of prototypes of a piezoelectric motor which has a planar diameter of 9 mm and a thickness of less than 0.8 mm. Hence, the goal is to continue work on the design, modeling, and fabrication of this piezoelectric motor to increase its performance for small scale robotics. The third objective is to leverage these fabrication techniques to create parallel robotic mechanisms which leads from my previous work on a three degree of freedom nanopositioning platform based on piezoelectric stack actuators. This work will deal with the design of transmissions and multiple degree of freedom joints with demonstration on a planar parallel five-bar robot, en route to the final long term goal of creating a miniature Stewart platform. This platform will achieve a large workspace with high motion frequencies. The overarching goal of this research program is to engineer low-cost piezoelectrically driven motors and mechanisms at the mesoscale. By employing the developed design, modeling, fabrication, and control techniques, a number of applications will be pursued such as surgical instruments, micro-assembly, manipulators for pico to femto class satellites, and miniature autonomous vehicles while offering a unique and novel opportunity for HQP training.