Velocity characterization and control strategies for nano-robotic systems based on piezoelectric stick-slip actuators

Abstract

Nano-robotic systems based on Piezoelectric StickSlip (PSS) actuators have become increasingly popular in research and industry for semi-automated and automated tasks at small scales. For an efficient use of PSS actuators, a series of research have been fulfilled on design process, dynamic modeling, driving methods and position control. However, there have been very few investigations on velocity control of PSS actuators. Velocity control is important to enable the nano-robotic system to generate a smooth and efficient motion and to avoid the undesired inertial shock of the end effector. This paper deals with velocity characterization and control strategies for nano-robotic systems based on PSS actuators. The range of achievable velocities on PSS actuators is studied in air and vacuum environments. This analysis allows the definition of a detailed map of the velocity characteristics in forward and backward directions of motion. Velocity control strategies are then studied based on an instantaneous velocity feedback and an average velocity feedback. Results of the proposed method show the first experimental demonstration of velocity control for PSS actuators in medium and high speed configurations opening new perspectives on the use of nano-robotic systems in dynamic automated tasks.