Abstract: In view of the fact that kinematics calibration can effectively improve the positioning accuracy of the robotic manipulator and inverse kinematics solution is the key to controlling the correct motion of the robotic manipulator. Taking the six-degree-of-freedom(6-DOF) hydraulic manipulator as the research object, the M-DH method and the geometric mapping method are utilized to establish the Ⅰ-type and Ⅱ-type kinematic error models of the hydraulic manipulator, and then the kinematic parameter deviations are identified based on the Levenberg-Marquardt(L-M) algorithm. In addition, the inverse transformation method cannot be leveraged to solve the inverse kinematics because of geometric parameter errors in the robotic manipulator. Therefore, an inverse solution calculation method combining analytical solution and partial differential theory is proposed. The simulation results reveal that after calibration by the L-M algorithm, the end position error of the hydraulic manipulator is reduced from 3.032 9 mm to 0.007 0 mm, the effect is improved by 99.77%, the position error of hydraulic cylinder 1 is reduced from 1.276 2 mm to 0.000 3 mm, the effect is increased by 99.98%, and the position error of hydraulic cylinder 2 is reduced from 1.167 0 mm to 0.001 2 mm, the effect is increased by 99.90%, which illustrates the validity of the calibration algorithm. Moreover, the simulation results also reveal that the proposed inverse solution calculation method can effectively obtain the inverse solution of the robotic manipulator.

Key words: hydraulic manipulator, kinematic calibration, Ⅰ-type kinematic error modeling, Ⅱ-type kinematic error modeling, inverse kinematics