Research On Measurement Technology For Center Of Gravity Based On Three-dimensional Scanning

The center of gravity is the inherent characteristic of the object and one of the important parameters in the measurement of the mass characteristic parameters of the object.Its properties directly affect the design and performance of the object.In actual production and life,rocket,aircraft,satellite and other objects need the center of gravity measurement.However,with the development and progress of science and technology,objects gradually tend to be refined and irregular,and their structure and shape are becoming more and more complex,which requires higher and higher accuracy of center of gravity measurement.In order to improve the center of gravity measurement accuracy of complex surface structural parts,two center of gravity measurement methods,suspension center of gravity measurement method and weighing center of gravity measurement method based on three-dimensional scanning,are proposed in this paper.The main research contents of this paper are as follows:(1)Research on center of gravity measurement method based on three-dimensional scanning.The three-dimensional scanning technology is introduced into the measurement method.Based on the gravity center measurement principle of suspension method and weighing method,the theoretical calculation models of gravity center based on three-dimensional scanning are established respectively.Based on the theory of least square method and the theoretical model of gravity center measurement based on three-dimensional scanning suspension method,the calculation method of multi ball center fitting best line and multi line optimal intersection is established to realize the theoretical calculation of point cloud fitting ball to gravity center;Based on the established theoretical model of gravity center measurement based on three-dimensional scanning weighing method,combined with the principle of torque balance,the solution equations of multiple measurement pose are established,and the calculation method of optimal gravity center is obtained.(2)Error analysis of center of gravity measurement method based on three-dimensional scanning.The fitting errors of point cloud stitching,point cloud fitting and hanging point extension line in the suspension measurement method based on three-dimensional scanning are analyzed;The influence of mass measurement on the center of gravity position,the angle error between the product coordinate system and the action line in the gravity direction,and the error of the measured position and attitude in the weighing measurement method based on three-dimensional scanning are analyzed.(3)Accuracy verification of measurement method.For the two measurement methods,the standard parts are designed respectively.The center of gravity of the two standard parts is measured respectively to obtain the actual center of gravity coordinates.The measurement results are compared with the theoretical center of gravity of the standard parts to obtain the measurement error.For 80 mm × 80 mm × For 80 mm standard parts,the measurement accuracy of suspension method is 0.4 mm;for 300 mm × 300 mm × For 10 mm standard parts,the measurement accuracy of weighing method is 0.6 mm.The relevant data obtained in the measurement process are substituted into the theoretical error calculation formula.The theoretical error is close to the experimental error,which proves the feasibility of the two methods.(4)Development of measurement system and application test experiment.According to the two measuring principles,the measuring devices are designed and manufactured respectively.The two sets of devices include mechanical structure system and sensing detection system respectively;The measurement application module is developed to realize the rapid solution of the center of gravity position.The center of gravity position of the airliner model is measured by the suspension method based on three-dimensional scanning,and the center of gravity position of the irregular assembly is measured by the weighing method based on three-dimensional scanning.The results show that this method can accurately obtain the center of gravity coordinates of different types of objects or systems.