A novel ring-beam piezoelectric actuator for small-size and high-precision manipulator

A new type of ring (joint)-beam (arm) element based on piezoelectric actuator is designed in this paper. By using piezoelectric ceramics, the vibration modes of two parallel beams are excited and coupled to form in-plane waves on the ring. As the piezoelectric actuator has the dual effect of acting as the power source and the main body structure of the arm joint, compared with the rotating joint using DC motor as the power source, the actuator does not need additional space to install the motor, which makes joint mechanism have the advantages of simple structure and small volume. Furthermore, the micro-displacement control of joints can be achieved by the characteristics of fast response and power self-locking based on the friction driving principle. A two-degree-of-freedom three-arm prototype of the joint mechanism is designed to obtain the parameters of the piezoelectric actuator and carry out related experiments. The prototype of the mechanism is 72 g in weight and 105 mm in length, and the maximum rotation angle of each joint is 210 deg. The experimental results indicate that, when driving frequency is 58.6 kHz and the driving voltage is 300 Vpp, the angular speed of the prototype reaches 45.9 deg/s, the resolution is 0.015 deg and the startup and shutdown response time are 35 ms and 21 ms, respectively. Due to its simple and compact structure, the manipulator have strong growth potential for meeting the requirements of wet hyperbaric environment. The characteristics of fast response time and high resolution enable good mobility and high precision.