Research On Measurement Method Of Plume Light Transmittance

Guided weapon is widely used in modern warfare. The performance of solid propellants, major acting energy in guided weapons, is playing a critical role in the internal ballistics attributes and specifications of the engine of weapons. At the same time, the identification accuracy of weapons is affected by guided signals attenuation, which is caused by plume generated by propellants. The ability of signal attenuation caused by plume is measured by light transmittance. There are some common methods of test for light transmittance measurement, such as detection method based on one testing node and detection method based on video image. Detection method based on video image has advantages such as strung expandability, highly accuracy and repeatability, but it has deficiencies such as instability, complexity, time-consuming and weakness of anti-interference ability at the same time.This paper studies the detection methods of plume light transmittance based on video image and summarizes its advantages and disadvantages. To solve the problem of instability of calculation results, this paper proposes an improved transmittance calculation algorithm. The improved algorithm divides target board into small regions using the continuity of plume distribution on space and time to achieve better transmittance calculation results. A new target board location algorithm based on board expandability is proposed for solving the shortage of accuracy, the new algorithm takes full consideration of characteristic of target board to decrease time consuming and increase accuracy rate. A verification method of calibration data is proposed for solving the weakness of anti-interference ability. First transmittance of a series of optical attenuator will be calculated by calibration curve, then the relative error rate between measurement value and real value will be calculated to evaluate validity of calibration data. Finally, a visualization method of transmittance based on multispectral is proposed for providing more visually appealing results.Experimental results show that the improved algorithm of transmittance calculation have advantages of highly accuracy and stability, the dynamic errors has decreased by 20%. The target board location algorithm based on board expandability solves the weakness of old location algorithm such as time-consuming and poor location precision. The verification method of calibration data fully screen all the valid calibration data as improved accuracy of result.The weakness of plume transmittance measurement will be most considered in further research, subsequent work will focus on further improving the accuracy of the solution, decreasing the influence by environmental light changes and improving calibration capability.