Research On Key Techniques Of Measurement Equipment Pose Parameter Tracing In Multi-degree-of-freedom Non-orthogonal System

Multi-degree-of-freedom non-orthogonal systems require external measuring instruments to obtain performance parameters when performing calibration and online measurement compensation.However,the static measurement calibration part of the ISO standard only specifies qualitative indicators of instrument performance and accuracy,and lacks quantitative analysis.The dynamic measurement calibration section does not clearly define the dynamic performance of the instrument.As people pay more attention to dynamic performance,qualitative and quantitative evaluation of the accuracy and stability of external measurement equipment has become an urgent problem to be solved.In this paper,the qualitative and quantitative analysis of the dynamic and static measurement accuracy and performance of the laser tracker and binocular vision system is carried out,and the high-precision characteristics of the multi-coordinate coordinate measurement method are used for traceability calibration.For the static measurement accuracy of the measuring instrument,this paper selects the positional characteristics of the industrial robots as the evaluation index,analyzes the relationship between the running speed of the robot and the position error,and reflects the response characteristics of the equipment under different conditions.Experiments show that the robot performance is stable,the overall trend of the measurement results of the two devices is first reduced and then stabilized,but there are differences in measurement accuracy.At the same time,the influence of the laser interruption number of the laser tracker on the instrument position measurement error is analyzed experimentally.It is found that the laser interruption number of the laser tracker has an accuracy influence of 0～3μm on the laser tracker accuracy.And the maximum influence degree accounts for the robot position error measurement is 6.6%,which can be neglected.For the problem of lower accuracy of binocular vision system position measurement,it is recommended to establish a high-precision coordinate system with standard length and obtain the correction amount after the conventional calibration,which can correct the system error of the binocular vision system.The method can increase the static measurement accuracy and repeatability of the binocular vision system by 32% and 80%,respectively,and can be quantitatively improved to the laser tracker accuracy level.For the dynamic measurement accuracy,this paper selects the trajectory characteristics of the manipulator as the evaluation index,selects the target moving speed and the instrument measurement distance as variables for studying the tracking performance and dynamic measurement accuracy.The sampling error will be caused by the different sampling frequency of the instrument,analyze the error by simulating the influence of sampling point layout,quantity and error on the target trajectory fitting.The influence of the trajectory fit determines that the fitting criterion is that the sampling points must be greater than 15 and uniformly distributed over 1/2 of the trajectories.It is concluded that the dynamic trajectory accuracy and repeatability error measured by the laser tracker and binocular vision system increase with the increase of the motion speed and the increase of the measuring distance,but the maximum tracking speed and dynamic trajectory measurement accuracy of the laser tracker both are superior to the binocular vision system.In this paper,a cooperative target is designed,and the receivers including large or small target balls and marker points)of the three measuring devices are evenly distributed at the end of the robot arm to complete the simultaneous positional characteristic measurement experiment.The experimental results show that the positional repeatability accuracy measured by the laser tracker and the binocular vision system is 10 μm and 24 μm respectively when the measurement distance is at 4 m,which are superior to the nominal accuracy.This is mainly due to the good environmental conditions and stable changes in the experimental site.