Abstract: Kinematic calibration is an effective way to improve machine accuracy. An improved error analysis and calibration method is verified through simulation, and it solves the kinematics calibration problem of a special 3-DOF parallel mechanism used in a forging manipulator’s bench clamp. Based on its forward and inverse kinematic model, the workspace is obtained, and kinematic accuracy analysis of the mechanism is carried out to obtaine the influences of all error sources of the mechanism on the terminal pose errors. The Jacobian matrix is obtained by using differential method. Simulation result shows that the difference between the identification value and the true value of the kinematic parameter error is less than 5%, which proves the effectiveness of the new accuracy analysis and calibration method for this special parallel mechanism.

Key words: Accuracy analysis, Kinematic calibration, Parallel-link machine