title: Error Analysis and Experimental Study of a Bi-Planar Parallel Mechanism in a Pedicle Screw Robot System.
abstract: Due to the urgent need for high precision surgical equipment for minimally invasive spinal surgery, a novel robot-assistant system was developed for the accurate placement of pedicle screws in lumbar spinal surgeries. The structure of the robot was based on a macro-micro mechanism, which includes a serial mechanism (macro part) and a bi-planar 5R parallel mechanism (micro part). The macro part was used to achieve a large workspace, while the micro part was used to obtain high stiffness and accuracy. Based on the transfer function of dimension errors, the factors affecting the accuracy of the end effectors were analyzed. Then the manufacturing errors and joint angle error on the position-stance of the end effectors were investigated. Eventually, the mechanism of the strain energy produced by the deformation of linkage via forced assembly and displacements of the output point were calculated. The amount of the transfer errors was quantitatively analyzed by the simulation. Experimental tests show that the error of the bi-planar 5R mechanism can be controlled no more than 1 mm for translation and 1° for rotation, which satisfies the required absolute position accuracy of the robot.
authors.affiliation: School of Mechano-Electronic Engineering, Xidian University, Xi'an 710071, China. qjduan@xidian.edu.cn.
authors.forename: Qingjuan
authors.initials: Q
authors.lastname: Duan
authors.affiliation: State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China. duzj01@hit.edu.cn.
authors.forename: Zhijiang
authors.initials: Z
authors.lastname: Du
authors.affiliation: State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China. yuhongjian99@126.com.
authors.forename: Hongjian
authors.initials: H
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China. wang_yf16@163.com.
authors.forename: Yongfeng
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China. dongwei@hit.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Dong
keywords: bi-planar 5R mechanism; dimension error; error analysis; joint angle error; non-parallelism of the rotation axis; robot-assistant spine surgery