Stick and Slip Actuators: design, control, performances and applications

This paper describes Stick and Slip Actuators, which can be included into the inertial drives' family. We propose several configurations and a modeling of these actuators. Stick and Slip Actuators present the advantage to allow long displacements (several centimeters or even more) at a high speed (several mm/s) with an ultra high resolution (< 5 nm). Moreover, they are simple, compact and offer a high stiffness. They are therefore perfectly well adapted to challenging applications such as micro-manipulation. Long displacements are obtained by stepping motion (stepping-mode), each step being typically 400 mm, while fine displacements with high resolution are made possible thanks to a scanning-mode. A simple controller, combining stepping- and scanning-modes, has been designed. The excellent performances of a 1-degree-of-freedom (1-DOF) actuator are demonstrated. An innovative concept developed at ISR, the so called "Monolithic Piezoceramics Flexible Structures" allowing to design extremely simple micro-manipulators, is also reported. Four prototypes are presented: a 1-DOF actuator, a 6-DOF platform and two 3-DOF mobile micro-robots. The authors also describe briefly four applications where Stick and Slip Actuators have been used successfully, namely: a sample holder for AFM (tilt), a micro EDM machine, a micro-assembly system and a micro-telemanipulation system for biological specimens.