Type Synthesis of Parallel Mechanisms with H+ and H- Co-axial Screw Pairs for Minimally Invasive Surgical Instrument

The performance of surgical instruments is crucial to determine the precision, efficiency, and safety of minimally invasive surgical procedures. Robotic surgical instruments typically utilize guide wheels to manage cable drives; however, this approach inevitably introduces the drawbacks of coupled motion, low stiffness, and low payload. In this paper, the parallel mechanisms (PMs) are employed to achieve wrist-like movement. A series of 2R1T PMs containing pairs of coaxial H pairs are synthesized based on screw theory, using the addition of moving joints and the identification of the self-rotation part (SRP), and new definitions of chains and platforms containing helical pairs are given. Besides, the kinematic solution, workspace performance, and transmission efficiency are analysis for the synthesized PMs. Finally, surgical instruments based on the synthesized PMs are presented and simulated for surgical applications.