A novel laparoscopic surgical robot (LSR) based on double-leg ultrasonic motor (DUM)

Magnetic anchor and guidance system has been widely used in laparoendoscopic single-site surgery with the benefit of small wound, wide field of vision (FoV), and convenience for repeated positioning. This paper introduces a novel three DoF laparoscopic surgical robot (LSR) based on double-leg ultrasonic motor (DUM) which features small dimension, fast response, and high positional precision. Piezoelectric ceramic (PZT) plates can excite longitudinal and bending coupled vibration of DUM and the two phase in-plane three order bending vibration can form traveling wave to drive DUM rotor. DUM stator is optimized by non-dominated sorting genetic algorithm-II for good consistency of two working mode frequencies and negligible influence of adjacent interference modes on working modes, which improves motion stability and driving efficiency. The mechanical characteristic of DUM under different chamfer parameters has been studied through comparative experiments and the design of robot prototype is completed further. For clockwise and counterclockwise rotation, the maximum no-load rotary speeds are 333.75 and 335.77 rpm, and the maximum output torques are 2 and 1.6 N mm. The experimental platform for FoV measurement is built to verify that LSR can adjust the posture to obtain suitable surgical FoV, indicating that the application of DUM in LSR has significant advantages and great potential.