Improved Design And Calibration Techniques Of Six-light-screen Optical Target

The velocity and impact location measurements of projectile are key components of firearm and ammunition range testing.Six-light-screen optical target has larger performance advantages and application prospect,since it provides an all-day and multi parameter measurement of projectile under severe approach angle.The velocity,flying direction and impact location of projectile can be measured in just one single shot.At present,the research progress of six-light-screen optical target just stays in prototype level since its size is relatively large as supporting unit and function units are seperated,its measurement precision is unable to meet practical requirement due to its limited solving precision caused by traditional geometry solving model and indirect light-screen calibrating technique.In order to promote the production process of the six-light-screen optical target,an engineering model for solving and accuracy analyzing,an improved structural design and a calibration technique are studied,according to its deficiencies of research progress in this paper.Firstly,a modeling and accuracy analyzing method based on plane equation was developed and a highly versatile engineering model and error transfer formula for six-light-screen optical target were deduced.Measurement accuracy decline caused by target distance and its error,light-screen tilt angle and its error,alignment error of light source and receiver,temperature variation,etc.were analyzed and compared under “double parallel” and“double V” six-screen structural model.Sets of position and velocity measurement error distribution data and graphics in effective sensor area were acquired.A structural parameter based on previous results and technical requirements was proposed and analyzed.It provides useful theoretical basis and data reference for the following practical design and accuracy estimation of six-light-screen optical target.Secondly,a new integrated six-light-screen optical target structure is designed.By imsert light source unit or receiver unit into certain support frame with an adjustable,individual mechanism,this new six-light-screen optical target has a more compact and simplified structure and easy to be installed,adjusted,and maintained.It can meet the technical requirements,and its capability of long term usage was proven by the finite element analysis results.Thirdly,a new calibration method of multible invisible light screen spacial location is proposed,based on actural screen thickness detection when using shadowing probe,and accurate spatial location detection when using double theodolite.The calibration principle and algorithm are discussed in detail.Some key techniques are researched and tested for practical,such as the extraction method of screen thickness center when using shadowing probe as subsitute of incoming projectile,and positioning optimization of double theodolite.At last,a calibration system was built to calibrate the screen parameters of a real multi-light-screen optical target.The calibration result shows a good agreement to another comparative calibration test result and proved the practicability and accuracy of this method.