Development, Control and Evaluation of a Mobile Platform for Microrobots

This paper describes the development, control and evaluation of a mobile platform for microrobots. The platform uses laser-structured piezoceramic plates equipped with ruby hemispheres in order to continuously rotate three steel spheres using the stick-slip effect. The spheres roll on the working surface and can thus move the platform in two translational and one rotational degrees of freedom. This indirect stick-slip actuation does not stress the working surface and can even operate on surfaces that are not perfectly flat. The exact geometry of the actuators is analyzed and an open-loop control approach is derived. As there are 27 piezo segments moving nine ruby hemispheres and three steel spheres, both the amplification hardware and the software algorithms need to be carefully designed. A prototype was built and evaluated to prove the concept. Basic data about the platform’s properties such as step length, resolution and actuation speed was gathered. The results are very promising as the platform can move with nm-resolution and with velocities of up to 10mm/s.