Development Of A Small-caliber Electromagnetic Railgun Orbital Structure Parameter Measurement System

For small-caliber electromagnetic railgun,measurement of track structure parameters has important reference significance for the research of bore wear mechanism and firing accuracy.Due to the special structure and aperture limitation of small-caliber track,the existing structure parameter measurement system has the problems of large reference positioning error and low measurement accuracy,For which,after in-depth analysis of the track structure characteristics,the track structure parameters measurement system of small caliber electromagnetic railgun was carried out,and the basis for track design optimally of railgun was provided.Firstly,according to the performance requirements of the track structure parameter measurement system,the overall scheme of the measurement system was formulated.By analyzing the influence of track spacing change and track theoretical axis positioning error on track straightness measurement,the track straightness measurement model was established.Which provided a basis for the design of track structure parameter measurement device.Secondly,based on the analysis of the overturning characteristics of the measurement datum caused by the convex structure,a self centering measuring device of track structure parameter measuring was designed.While the device moved along the axial direction,the centering function was realized.and the measurement of the track depth,track spacing and track straightness were completed.Thirly,by analyzing the nonlinear output characteristics of the two-dimensional positionsensing dector(PSD)in the track straightness measurement module,a binary polynomial-zone PSD correction model was established.The experimental results show that the measurement error can be controlled within 5.02 micron by using cubic polynomial correction model.By designing software system based on LabVIEW,the calculation and display of track structure parameters were realized.Finally,the performance of the measurement system was verified.According to the track structure,the verification tool of distance measurement was designed,the measurement error of the track distance measurement module was verified to be no more than 16 micron by comparing the measured value of the track distance measurement module with the measured value of the three coordinate detector;the measurement error of the track depth was verified to be no more than 1 millimetres by measuring the track of a small-caliber electromagnetic railgun,and the stability of the measurement system was verified as well.The measurement uncertainty model of track structure parameters of small caliber electromagnetic railgun was established,and the influence of sensor precision,installation error and machining on the uncertainty was analyzed.The evaluation results shown that the measurement uncertainty of each parameter met the system requirements.