Torque for an electromechanical integrated harmonic piezodrive system

In this paper, an electromechanical integrated harmonic piezodrive system is proposed in which piezodrive principle is combined with harmonic drive and movable tooth drive principles, and sliding friction between rotor and stator is changed into rolling mesh. It can cause a significant increase of the output torque as well as increase of the operating life and efficiency. Here, the structure of the motor is determined and its operating principle is illustrated. The deformation energy of the flexible ring is analyzed under the piezoelectric excitation. The equation of the output torque for the drive system is deduced. Using the equation, the output torque and its changes along with the system parameters are investigated. The results show that an output torque larger than that of the normal bar-type ultrasonic motor is obtained, and the output torque is influenced by the system parameters such as the length, thickness and material of the flexible ring, the excitation voltage, and the speed ratio obviously. The results are useful for further study and application of the drive system.