Development Of A Joint Arm Chassis Measuring Instrument

The popularity of automobiles facilitates people's trip,but it also brings many unavoidable problems.In order to ensure normal driving and reduce environmental pollution,vehicle chassis needs regular maintenance and tes ting.In many chassis detection technology,three-dimensional detection technology can not only ensure the location size of the key quality points,but also ensure the accuracy of its functional dimensions.Therefore,it is the best measure method for vehi cle chassis at present.This project is based on three-dimensional detection technology,completed the design of vehicle chassis measuring instrument.In this paper,the design of the measurement system based on the joint arm coordinate measuring machine is decided first of all.Based on the function requirements of articulated arm CMM,the hardware is designed,and the functions of signal extraction,processing and sending of rotary encoder are realized.According to the D-H model method,the kinematics model of the articulated arm coordinate measuring machine is established,and the coordinate measuring function is realized.In order to improve the measurement accuracy,the calibrated model parameters are analyzed,and the calibration equation is constructed with the kinematic model.The least square method is used to solve the equation.Finally,the optimal estimation of the model parameters is obtained.The experimental results show that the accuracy of the calibrated coordinate machine reaches to 1mm,and the repeatability of single point repeatability is within 1mm.The relationship between the coordinate system of the measuring machine and the coordinate system of the chassis is solved by the theory of rigid body transformation,and the result of the solution is converted to the chassis coordinate system by the result of the solution.According to the detection function of the vehicle chassis measuring instrument,the demand analysis of the upper computer is put forward.Finally,the software system of the measuring instrument is designed based on this.The chassis testing experiment was carried out after the automobile chassis measurement system was perfected.The experimental results show that the design of the chassis measuring instrument conforms to the standard of the chassis detection.