Study On Measurement Technology With Six-light-screen Array

Based on the present light screen measurement technology, a method used six-light-screen array to measure the projectile velocity, flying direction angle of velocity and impacting position is put forward in present thesis. The technology of relevant circuit and algorithm are designed in this thesis.The main contributions are as follows:(1) A six-light-screen array structure is given and analyzed. The measurement formula of projectile velocity, flying direction angle and impacting position is demonstrated. The six-light-screen is the key part of this measuring system, which can synchronously measure all the above parameters.(2) The light screen in the system is realized with a large area light screen target. The receiver circuits which composed of some PIN photoelectric cell, Opto-electronic transform circuit, preamplifier circuit, amplifier circuit, trigger circuit and anti-disturb circuit have been designed.(3) Algorithms for acquiring the moment on which a projectile going through a light screen is researched. The algorithms based on projectile nose, base, mid-screen, mid-projectile, and correlation are theoretically analyzed. And a geometry computational model that a projectile go through light screen is built up. Those algorithms are simulated on MATLAB with simulated signals. The result demonstrated that the methods such as mid-screens, mid-projectile, and correlation could accurately get a time and have less sensitivity to the discrepancy of parameters of mechanical structure and amplifier times. The algorithms are verified by a real projectile test.(4) The measurement precision of studied system is analyzed, and it is proved by air-gun projectile impacting experiment. The result demonstrated that the system can meet the expectant need.(5) A method to measure the flying parameters of swarm of fragments is put forward. The DAQ (Data Acquire) system can capture the analog signal when the fragments passed through the screens, and the time between each signal is calculated by the algorithm. According to the location coordinate of the location identifier and six time sequences of the fragments, the real velocity and flying angle of each fragment can be calculated, and the false combinations of the six times can be eliminated. The method is proved to be accurate and effective by the computer simulation.