Design And Error Compensation Of Passive Tracking Measurement System

Under the new development pattern of double-cycle development in China,industrial robots,as high-end manufacturing equipment,are gradually increasing in use density in various industries,and it is imperative to localize them.However,industrial robots have low absolute accuracy and need to be calibrated regularly to ensure product quality and processing efficiency,which will inevitably put forward higher requirements for industrial robot spatial position accuracy measuring instruments.As an instrument that breaks through the limitation of measurement space,laser tracker plays an increasingly prominent role in precision correction of industrial robots.Traditional laser tracker adopts active tracking method and has complex tracking control system,which is too expensive to be popularized.Therefore,it is necessary to develop a space measuring instrument with simple measuring principle and low cost.In this paper,a passive tracking and measuring system is designed.The radial telescopic movement is realized by using a lightweight roller and double sliding rods.The radial telescopic length of the telescopic mechanism is measured by grating measuring system.When working,the standard steel ball at the end of the telescopic mechanism is attracted to the measured target by magnetic force,and the measured target is passively tracked to measure the spatial position coordinates of the measured target.Compared with the complex active tracking and measuring system,this passive tracking and measuring system has the advantages of light weight,smooth movement and low cost.In order to improve the accuracy of the measurement system,firstly,the main error items of the system are comprehensively analyzed,and an error compensation model including 7system geometric errors and 1 unknown parameter is established based on the multi-body system error theory.Then calibrate the parameters of error compensation model step by step:calibrate the angle measurement error of the two-dimensional turntable circular grating angle encoder with multi-tooth indexing table and high-precision photoelectric autocollimator,and compensate the angle measurement error with harmonic error compensation method.The verticality error and off-axis of two rotating shafts of two-dimensional turntable are measured by double-sided test method Two linear axes of a high-precision two-dimensional motion platform are used to construct linear motion constraints,and an identification model of the pose error of the optical axis is established,and then the off-axis amount and verticality error of the optical axis and the two rotating axes of the two-dimensional turntable are measured.Finally,based on the high-precision two-dimensional motion platform,the repeatability and compensation effect verification experiment of the passive tracking measurement system is designed and completed.The experimental results show that within the measuring range of 150mm×150 mm,the repeatability uncertainty of the passive tracking measurement system for fixed points in space is better than ±9.8 ?m.After error compensation,the spatial positioning accuracy of the system is improved by 66.9%,and the accuracy of the passive tracking measurement system is effectively improved.