Piezoelectric manipulation robotic system for automatic handling of micrometric objects using visual servoing control techniques

This paper presents the design of a micro-manipulator based on piezoelectric actuators, that may have potential applications for handling biological tissue and animal cells. This article focuses on developing the electronic instrumentation, the evaluation of several controllers as well as the inclusion of the visual servoing components. The robotic system consists of a robotic arm made with 6 degrees of freedom and a dual-finger gripper made with 2 bi-morph piezoelectric actuators. The instrumentation includes the electrical devices that drive the actuators, dc-motors and, piezoelectric, which allow the micromanipulator to handle small objects. In view of the proposed manipulator aims to use visual servoing, the instrumentation stage includes the implementation of electronic cameras to close the control loop. This study evaluated a class of extended state feedback as well as a class of twisting controllers with the application of a super-twisting algorithm operating as a robust exact differentiator for each of the angular motions in the robotic manipulator. The comparison proved that the norm of the tracking error reduced faster and attained smaller values when the twisting controller was implemented. The application of low-pass filters aided to reduce the chattering effect on the robotic manipulation tasks. The motion of the piezolectric actuators was also mobilized using the same controller considering the robustness of the twisting controller to overcome the effect of the hysteresis nonlinear effect. The proposed controller succeeded to complete the gripping process using the given piezoelectric configuration.