Measurement model and algorithm for measuring flight parameter of parabolic trajectory by six-light-screen array

Abstract To solve errors of current light-screen array in terminal trajectory measurement, a measurement model and algorithm for calculating the external trajectory flying parameters of the projectile with variable velocity and parabolic trajectory basing on the six-light-screen array are put forwarded in the paper. The spatial position of the light-screen array is analyzed, planar equations are constructed by analytic geometry. This study also investigates the impact of gravity and air drag force on projectile flight trajectory and establishes a space trajectory equation of projectile. The spatial impacting position, the velocity and the velocity reversal angles of a projectile can be correctly calculated with target placement parameter and time sequence of the projectile passing through the light-screen array. Measurement formula and calculation method are deduced in consideration of the influence of gravity only and the influence of gravity and air drag force. To verify the validity of the research method, this study adopts XGK-08 type six-screen array measurement system and wooden target to compare the projectile impacting coordinates of 7.62 mm rifle cartridge. Result shows that when the detecting area is 3 × 3 m2, the coordinate measurement error of the model is less than 2.5 mm.