Background: Compared with the traditional series mechanism, the parallel mechanism
has a better kinematic performance. Structural size error is the main factor affecting the accuracy of
Objective: The paper mainly studies the compensation of the rod length error, the moving platform
radius error and the fixed platform radius error of 3-UPU parallel mechanism.
Methods: To establish a generalized forward and inverse solution equation with error compensation,
the position change of the moving platform is measured by a laser interferometer, and the change
amount of the three connecting rod lengths at the corresponding position is recorded. Optimized by
least squares method, the optimized error compensation values are compensated to the kinematics
algorithm of the numerical control system, and the positioning accuracy is improved.
Results: The results show that the positioning accuracy is higher when the mechanism moves in the
lower plane, and the positioning error in the z axis direction is smaller than x, y, y=x, y=-x axis.
Conclusion: After the error compensation, the overall positioning accuracy of the mechanism is
increased by 60%.