Robust Force Control of Piezoelectric Precision Positioning Actuators Using Self-Sensing Method

In this paper, a new method for sensorless force control has been developed based on position and force self-sensing in piezoelectric positioning actuators utilized for low frequency and long-term applications in micro-robotic and micromanipulation tasks. In each of the insertion and retraction phases during contact with objects, this developed system can simultaneously detect force and position in piezoelectric positioning actuators and control the exerted force to prevent any damage to objects. The estimation of the actuator position and the externally applied force are based on the integration of the online charge and capacitance measurement methods. Based on the detected position and measurement of the actuator capacitance, the applied force is estimated and can be used for further control purposes. Furthermore, To control the exerted force on objects, a robust impedance force control algorithm is proposed. As an experiment, the proposed self-sensing system and the designed force control algorithm are implemented on a piezoelectric micro-positioning actuator entering in contact with an object. The experimental results demonstrate the effectiveness of the proposed self-sensing approach in both force estimation and control.