Research On Variable Measurement Space Technology Of Articulated Arm Coordinate Measuring Machine

The Articulated Arm Coordinate Measuring Machine(AACMM)is a common 3d measuring equipment,it has the advantages of large measuring range,good flexibility,easy to carry and can be used in industrial field measurement.In actual measurement,it is found that only part of the measuring space is used when the AACMM is used to detect small parts,that is,the measuring space of the AACMM is redundant.At the same time,the measurement accuracy of the AACMM is affected by the number of joints and the series of structures,and the joint error will be amplified with the length of the rod.Therefore,the research focus of this paper is to improve the measurement accuracy by reducing the joint freedom degree of the AACMM and changing the measurement space of the AACMM.This paper presents a concept and implementation scheme of variable measurement space AACMM.By locking different joints,the measurement space of the AACMM can be changed,so as to improve its measuring accuracy.The main research contents include:Firstly,Build the mathematical model of the variable measurement space AACMM.The measuring principle of variable measurement space AACMM is analyzed,and the kinematic model is constructed and verified by simulation.The error source of variable measurement space AACMM analyzed and the error model is established.The error model of the AACMM in variable measurement space is compared with that of traditional AACMM to provide theoretical basis for subsequent research.Secondly,The joint error model was constructed to analyze the influence of the joint error on the measuring precision of the AACMM.The change of measuring space and measuring precision of the AACMM after locking different joints was analyzed to provide basis for selecting suitable measuring space,and a joint combination selection method for common parts was proposed for the measurement space with high applicability.Thirdly,The influence of single-point calibration method and multi-point calibration method on the measurement accuracy of variable measurement space AACMM is studied.The multi-point calibration method is selected according to the simulation results for subsequent research.A multi-point calibration simulation scheme is designed for the AACMM in variable measurement space,the measurement accuracy of the variable measurement space AACMM and the traditional AACMM after multi-point calibration are simulated and compared.Lastly,The experimental scheme was designed,the experimental platform was built,and two kinds of joint fixation schemes were proposed and selected.By comparing the measurement accuracy of the variable measurement space AACMM and the traditional AACMM,the superiority of AACMM and the feasibility of the AACMM are verified.