Research On Measuring Method Of LOS Angular Rate Based On Single Camera And DSP Platform

Line-of-sight(LOS)angular rate is a very important parameter for a navigation and target-guidance system.In an accurate terminal guidance system especially,the main guidance information provided by the terminal guidance is the LOS angular rate.Therefore,the extraction and calculation of LOS angular rate has been a very important research project.By studying the research status of the existing LOS angular rate,a method to calculate LOS angular rate with only image sequences of one single camera is proposed in this paper and carried on a DSP platform to test and verify.The method is a view on the fact that the LOS angular rate is difficult to obtain in a strap-down inertial navigation system and that the development of navigation system is smaller and lighter.Target detection and tracking is an important precondition and basis for the calculation of LOS angular rate,which has great influence on the efficiency and accuracy of follow-up calculation of LOS angular rate.The target detection tracking is introduced in this paper therefore.Firstly,two methods,temporal difference and background subtraction target detection,are introduced and tested,with the advantages and disadvantages,and applications of the two methods shown.Then the mean-shift target tracking technique is introduced,which is a simple and fast target tracking technology and is suitable for a small and fast system.And the tests show that target is well tracked with the mean-shift method.The model and method to calculate the LOS angular rate are deduced with the basis of previous studies.With the coordinates system defined and converts among these coordinates,the LOS angle and Body LOS angle are expressed by these coordinates,and the method of calculation of LOS angular rate is indicated therefore.The procedure is introduced as follows,firstly Body LOS angle is calculated with the moving object coordinates in the image sequences,then missile attitude angle is obtained by images matching,and lastly the LOS angle and LOS angular rate are calculated with the Body LOS angle and the missile attitude angle.Experimental results show that missile attitude angle are obtained well by the images matching,with the attitude transform error less than ±5%,and the LOS angular rate can be better restored using Kalman filter,when body LOS angle and missile attitude angle being noised.The method has a practical value,being applicable to micro-small target detection and guidance system,eliminating gyro inertial elements,and reducing the weight of detecting devices.