Analysis Of Pose Error Of The Probe On 3-PUU Parallel Coordinate Measuring Machine

Parallel mechanism is widely used in robot,machine tool and other fields because of its advantages of small motion inertia,large stiffness and average error effect.Based on the above advantages,a parallel coordinate measuring machine with 3-PUU configuration is developed,aiming to expand the application of parallel mechanism in the field of precision measurement,which was supported by national natural science foundation of China.The analysis of the error characteristics on the parallel coordinate measuring machine will be focused in this paper.Firstly,based on the structure of 3-PUU parallel coordinate measuring machine and the principle of closed-loop vector method,the inverse kinematics solution and forward kinematics solution model of the probe's pose are established,and the pose error model of the measuring machine's probe is established.According to the pose error model and the basic principle of Monte Carlo method,the pose error solution program is designed,so as to realize the measurement function and the analysis of error of the measuring machine.Secondly,the influence of hinge position error on the pose error of the probe is studied.The hinge position error includes the slider motion error component and hinge assembly position error component.In view of the movement error of the slider,the straightness error is measured by the dual frequency laser interferometer,and the angle error is measured by the autocollimator.Monte Carlo method is used to analyze the probability distribution and standard deviation distribution of the position and attitude error of the probe under the coupling action of the hinge assembly position error and the slider motion error.The analysis shows that the hinge assembly position error has more significant influence on the position and attitude error of the probe than the slider motion error.Thirdly,the influence of the rod length error on the pose error of the probe is studied.Monte Carlo method is used to analyze the probability distribution and standard deviation distribution of the position and attitude error of the probe under the error of rod length.The experiment of the length error is carried out.The experimental and simulation results show that the influence of rod length error on the position error of the probe in the X-axis direction is greater than that in the Y-axis direction.Finally,the influence of slider motion error,hinge assembly position error and rod length error on the pose error of the probe is studied.Monte Carlo method is used to analyze the probability distribution and standard deviation distribution of the position and attitude error of the probe.The research shows that the hinge assembly position error has the most significant influence on the pose error of the probe,and the slider motion error has the least influence.The error distribution is different between different positions and different pose error components in the workspace,and the pose error at the edge of the workspace is the largest.Specifically,the X-axis position error is the largest,and the Zaxis position error is the smallest.The angle ? error is the largest,and the angle ? error is the smallest.