The Design Of A High-precision Measuring Method And The Measuring System For Mass And Centroid Measurement

Mass and centroid were intrinsic properties of missile.High accuracy of mass and centroid can decrease difficulty for missile flight control.It was an important guarantee for missile flight test success and hit rate increasing.Therefore,guarantee of mass properties accuracy became one of the basic requirements of missile assembly.To do this,beside manufacture and assembly accuracy needed to be increased,measuring precision of these mass properties also should be improved.Accurate and effective measuring of mass properties were premises of high mass and centroid accuracies.In consequence,measuring and analysis of missile mass property parameters were important work for missile manufacturing.Unfortunately,missile mass property parameters measurement system was usually specialized for specific type,measuring precision was not high and versatility was bad.It was no longer fitted for high accuracy demand of missile mass property.Firstly,several kinds of mass and centroid measurement methods were compared and analyzed.Properties and range of each measuring method were introduced.Then,the Off-centering Measuring Method was proposed according to objects outline and measurement accuracy requirement.The off-centering sensor force needed to balance object off-centering torque was reduced by extending of sensor arm.Therefore,low measurement range and high resolution off-centering sensor could be chosen.Meanwhile,measurement theory and steps were demonstrated in detail.Measurement error and influencing factors were analyzed.This would be theory basis for High Precision Mass Properties Measuring System design.Based on the Off-centering Measuring Method,mechanical system of High Precision Mass and Centroid Measuring System was designed.In order to increase measuring accuracy and efficiency,meanwhile extend service life of measuring system,functions like auto-lifting,auto horizontal degree adjusting and offcentering measuring mode transformation were designed.As the sensitive components,mass sensors were most important parts of measuring system.Its service life influenced the life time of the whole system.Though the auto-lifting function,load apply only happened during measuring.As a result,upload time was decrease greatly,mass sensors get well protection,and therefore,system service life was extended.The auto horizontal degree adjusting function was easily to manipulate,and kept system horizontal degree,improved measuring accuracy.Offcentering measuring mode transformation mechanism separated centroid measurement and off-centering measurement by structure design,therefore both two measurement accuracy could be guaranteed.Supporting assembly of testing tool could slide along measurement crossbeam.Different length missile could be fitted.According to different dimension of missile,universality for diverse product measuring would be realized just by changing of different ring tools.Corresponding for demands of high accuracy,high efficiency and easily operating,electrical sub-system of High Precision Mass and Centroid Measuring System was designed.Then,the chosen of weighting sensor and measurement data acquisition card design was introduced detailed.Electronic integrated test software was developed based on PM Designer.Afterwards,the Testing Application Program on host computer was designed base on Visual Basic 6.0.Measurement datum were recorded and analyzed by Access database.The operate system was easy to operate.Mechanical engineers can operate measuring without training.Testing result display was clearly,and print out was convenient and fast.This Electronic integrated test equipment special software could be used in different product mass property parameters measuring.Apparently,this software was universality.Eventually,verification rules were established and accuracy detection plan based on standard cylinders was made to verify High Precision Mass and Centroid Measuring System measuring accuracy.System mass measuring accuracy and repetitive accuracy,centroid measuring accuracy,off-centering centroid measuring accuracy was checked based on mass property parameters of standard cylinders which were verification by a metrology institute.The results show that measuring accuracy of the High Precision Mass and Centroid Measuring System was high,and measuring data was stable.To keep system accuracy during real products measuring,mass,centroid,off-centering centroid measuring accuracy of the standard cylinders after assembled with ring tools were verified.The verification results were further indicated that measuring accuracy of the High Precision Mass and Centroid Measuring System was high and stable enough for real product mass property parameters measuring.