Research On Wireless High Precision Infrared Velocity Measurement System

The speed of the flying projectile is a critical content of assessment index of the weapon system. It is an important indicator of measuring gun’s features, ammunition properties and ballistic characteristics. To the requirements of improve the projectile speed measuring precision and ensure the test safety, wireless infrared speed measure system is developed by the average speed measurement method.According to implementation of the light screen, mathematical model of light energy distribution in the screen is built for studying the system’s output sensitivity. Comparing the MATLAB simulation value and the measuring results of light intensity validates the correctness of the theoretical simulation. An adjustable double slit diaphragm is designed embedding in the target shell. It improves the uniformity of the light screen target’s intensity distribution and enhances the ability of resistance to stray light’s interference.According to 0.1% technical index of the system speed measuring relative error, analog signal amplifier circuit and the shaping circuit with accurate extraction of projectile passing moment are designed respectively. Different time extraction methods are simulated to analyze the precision of the measurements, and collecting the firing signal to validate the correctness of the theoretical simulation. In the Digital part, the anti-interference circuit based on CPLD and the control & transmission circuit based on single chip microcomputer are designed. On the basis of the hardware circuit, the software of wireless infrared speed measuring system is designed completely. The CPLD completes the extraction and conversion of the projectile passing interval time; the CPLD and wireless module are controlled to complete and the data transmission by MCU. PC adopts Lab VIEW programming; it can communicate with lower machine communication through the wireless module. The PC program can set the parameters of related speed measurement, display and store the test results etc.Through the experiments comparing with the standard measuring device show that the system has a strong ability of anti-interference, can meet the remote testing requirements of different caliber projectile and can reach a high speed measuring precision of 0.1%.