An Error Compensation Method for Surgical Robot Based on RCM Mechanism
Ming Bai, Minglu Zhang, He Zhang, Linjun Pang, Jie Zhao, Chunyan Gao
Abstract
Remote center of motion (RCM) mechanisms, which are widely used in surgical robots, use mechanical constraints to realize movement around the RCM point. Errors in processing and assembly cause deviation of the RCM point and position error of the end-effector, and these deviations cause the robot to exert excessive force on the incision during movement, leading to adverse effects that reduce the safety and accuracy of surgical robots based on the RCM. Based on kinematics calibration, this paper proposes a solution of forward and inverse kinematics considering the RCM point deviation, which can simultaneously reduce the positioning error of the end-effector and the deviation of the RCM point. First, a calibration method based on the combination of the model and neural network is used to improve the kinematic accuracy of the robot. Second, a forward and inverse kinematics solution applied for RCM mechanisms is proposed, which reduces the RCM point deviation during surgery. Finally, experiments on an established surgery robot were performed, verifying that the proposed method can simultaneously reduce the RCM point deviation and the position error of the end-effector. The proposed method is found to be superior to other methods and can improve the safety and accuracy of surgical robots.