Research On Error Modeling And Compensation Of Contact Probe For Articulated Arm Coordinate Measuring Machine

The accuracy of instrument measurement can affect the whole industrial development level to some extent.So,how to improve the precision of the instrument is a common problem faced by the industry of precision instruments.Articulated Arm Coordinate Measuring Machine(AACMM)is a high precision measuring instrument for space coordinate measurement.However,it's formed by measuring arms and measuring joints in series,resulting in low measurement accuracy.At present,the research mainly focuses on the analysis and the static error sources,and the error sources such as measuring force and measuring temperature is insufficient.So,in this subject,the research focuses on the influence of measuring force between the probe and the measured object on the accuracy of AACMM.Than further analyzes the mapping relationship between the measuring force and the equivalent diameter of the probe.Finally,the measurement error caused by the thermal deformation of the machine is studied,and the error compensation is carried out.About the problems of measuring force,in this paper,we used the basic principle of Hertz formula and cantilever probe to establish local compression deformation model and rod bending model,and used the experimental results to establish the error compensation model based on least square method.The results show that the maximum error compensation decreased about 47 um after compensation,the average error is reduced by about 82%.On this basis,the mapping relation between equivalent diameter and measuring force is obtained by experiment,and the least square method is used to fit the measuring error,which compensates the diameter error of probe caused by measuring force.The maximum error is reduced by about 43 um,the average error is reduced by about 28.5um,and the average measurement accuracy is improved by about 87.7%.Finally,the temperature variation law of main structural parameters and the variation trend of measurement error of AACMM under the experimental temperature of 20? are studied.The algorithm error compensation model is established by using multiple linear regression in thermal deformation.With this model,the compensation of thermal deformation error of the structural parameters of AACMM is realized,and the average measurement error is reduced from 71.5um to 33.5um.