Structure Design And Precision Research Of Flexible Coordinate Measuring Machine

At present, with the development of industrial measurement and processing technology, the application of the traditional orthogonal coordinate measuring machine is restricted on many occasions. For example, on-line detection of the production line parts, test of the workshop scene parts, measure of the large parts, converse data collection of outdoor items in the environment, and so on. Compared with the traditional coordinate measuring machine, non-orthogonal Coordinate Measuring System's mechanical structure uses joint arms, and it is small size, light weight, flexible, easy to transit, surveying a large space, simple to operate, low-price and so on. Then its application is growing in recent years. However, the relatively low accuracy limited its widespread use. This thesis studied a new type of non-orthogonal coordinate measurement system (flexible coordinate measuring machine). The study focused on the accuracy of coordinate measuring machine and structural design, established system kinematics model and error model, discussed the relationship between the parameters of the structure and the accuracy optimize, and then done the simulation analysis and experimental verification.Firstly, design the mechanical structure of flexible coordinate measuring machine, determine the number of the structure freedom and the way of joint connections. Use a slip ring to connect the measure signal lines between each of the joints, and so achieve the unrestricted rotation of the three joints. The material of the joints used aviation aluminum alloy, and the material of articulated arm used carbon fiber. By this way reduce the weight of flexible coordinate measuring machine and it can be easy to operate, at the same time also reduce the heat distortion of the arm which is caused by changes in temperature.Establish the kinematics model and error model of the flexible coordinate measuring machine. Including specific, the first step established an ideal motion equation, and the second step worked out the integrated measurement equation after considering the structural parameters' error and the angle sensors' error, and the third step established the system error model and random error model under the integrated measurement equation.Analyses the relations that between the structural parameters' error and the probe location accuracy. Focus on the optimization of the length of the joint arms and the parts' tolerance. Study the stress and strain of key parts in ANSYS. Verify the design of the structure is reasonable.Simulate the system error model and the random error model in Matlab, and verify the correctness of the model. Calculate the system error and random error in the calculation example, and calibrate the system error in calibration model, then effectively eliminated the impact of system error to the measurement accuracy.Finally, the research and the conclusions of the thesis are summarized.