Dynamic Modeling and Experimental Research on Low-Speed Regulation of a Bending Hybrid Linear Ultrasonic Motor

The principle of friction force drive of ultrasonic motor (USM) results in complex nonlinear behavior. The friction force at the contact interface is easily affected by factors such as surface morphology, friction coefficient, and sliding speed especially when the USM is running at low speed. In order to improve the low-speed characteristic of the USM, as the vibration amplitude of the bending hybrid USM can be regulated independently along two orthogonal directions, an orthogonal vibration decoupling method for low-speed regulation was proposed. The complete dynamic model of a bending hybrid USM was first constructed to explore the working mechanism for low-speed drive. The USM was working at the continuous operating modes, the dynamic response of the runner and low-speed characteristic of the USM under three speed regulation modes were then simulated and discussed. At last, a proportional integral differential (PID) closed-loop control system of USM for speed regulation was established. As a result, the maximum errors of the target speed of 1 mm/s and sine wave tracking of 5 mm/s are 0.2 mm/s and 0.67 mm/s, respectively, which verified the availability of the proposed method.