Motion Decoupling Method for a Single-Port Surgical Robot with Joint Linkage

Aiming at the strong motion coupling of the execution instruments of the single-port laparoscopy (SPL) surgical robot from the driving space to the operating space, the joint linkage configuration is studied to realize the motion decoupling and simplify the kinematics model. Firstly, the motion characteristics of the linkage configuration are analyzed and a roller constrained articulated joint is designed. Subsequently, a 7-DOF (degree of freedom) instrument with linkage configuration is developed, and it can implement 2-DOF "linked deployment". The D-H (Denavit-Hartenberg) model is established to analyze the posture separation of the linkage configuration device, and the inverse kinematics is directly solved by the analytical method. Then, the flexibility of the end of the surgical instrument at a given point is measured based on the solid angle, and the joint arrangement of the distal segment of the linkage configuration instrument is optimized. Finally, the experiment shows that the posture of the end of the linkage configuration instrument depends only on the distal joint, and the "linked deployment" only changes the position of the instrument end. The maximum error from the driving space to the joint space is less than 3°, and the drives of the proximal and distal sections don't interfere with each other.