Research On Precision Guidance Technology For Guided Ammunition

According to the demand of guided ammunition to precison guidance technology,this paper is devoted to three issues: comparison of traditional guidance law,theory and application research of biased proportional navigation for impact angle constraint,and that of switch gain proportional navigation with the same constraint.This paper could provide theoretical support for the development of national precision guided ammunition.In the paper,the status and trend of development about foreign advanced precision guided ammunition combined with traditional and multi constrained guidance law and the problems to be further studied is summarized.Considering different guidance system error,the guidance accuracy of proportional navigation(PN),velocity pursuit(VP)and integrated proportional navigation(IPN)is compared comprehensively,by constructing three linear models of the three guidance laws with same system dynamics.Some relevant conclusions are obtained.When terminal guidance time is sufficient,all the deterministic errors has no influence on the accuracy of PN with N?3 and IPN with N?2,but the VP accuracy is degraded by seeker zero position error.The three guidance laws have been influenced by random errors,although the terminal guidance time is provided,also the miss distance of PN by random errors is equivalent to that of IPN,both of which is greater than that of VP.The biased proportional navigation for stationary targets(BPNS)is studied.According to the relative geometric kinematics between missile and targets,the functional relationship between required integral quantity of bias and expected impact angle is derived.Stability region of BPNS is given by using the phase plane trajectory curve.Then BPNS is compared with Trajectory Shaping Guidance law(TSG)and some conclusions are obtained from trajectory simulation and application analysis.BPNS need more overload and wider field of view and have a little less impact angle accuracy than TSG,but it can works well without the remaining flight time and line of sight information,implying much less hardware requirements,so the former is more applicable to low cost ammunition.Biased proportional navigation for moving targets at uniform speed(BPNM)and Close-loop biased proportional navigation for maneuvering targets(C BPN)are both studied.When it comes to constant maneuvering targets,the overload and field of view of CBPN is is smaller than C BPN.Consequently,C BPN need more guidance information.Switch gain proportional navigation guidance laws are also included in the research.In theory,the ability of them about raising impact angle has been proved and general rules of overload and field of view demand of them are given.A kind of switch gain proportional navigation realizing impact angle and field of view constraints(SPNGF)by taking middle navigation gain as one is analyzed.Trajectory simulation imply that the impact angle ability of SPNGF is obviously influenced by the initial look angle because SPNGF with small initial look angle could not make full use of the seek field of view.At last,a switch gain proportional guidance law within the constraints of field of view and overload(SPNGO),using the derived function relation among navigation ratio,overload and field of view,is studied.Trajectory simulation shows that the SPNGO could not only make full use of trajectory resource,but also enhance impact angle ability of switch gain proportional guidance law.From linear model of SPNGO,the conclusion that the deterministic errors have no influence on guidance accuracy with sufficient terminal flight time could be obtained.