Research On The Key Technologies Of The Infrared Imaging Guidance System In A Novel Loitering Missile

As the rapid development of precision-guided weapons and equipment with high technology and the requirement in actual applications,the key techniques of infrared imaging guidance system(IRGS)used for a novel loitering missile are studied in the thesis.Much effective work is carried out,which includes the design methods of performance indexes,the influence of missile attitude motion on IR imaging quality,modeling and analysis of transient pointing error and the miniature design of IR imaging system,in order to successfully design and develop the IRGS and loitering missile with the characteristics of low cost,miniaturization,high reliability and tracking precision.The main research works are as follows:1.The develop tendency of loitering missile and IRGS is summarized.The weakness of the existing loitering missile,needing to be catapulted off and unable to scare at the target for a while is then pointed out.In order to solve the above problems,a novel loitering missile structure with IRGS is presented,which not only has the ability of landing and taking off autonomously,but also overcomes a general problem of weak performance of yaw in multi-rotor,by means of the special configuration of multi rotors.Then,the develop tendency of the IRGS index design,the IR imaging system miniaturization and the pointing accuracy are reviewed and discussed in detail.2.The design methods of major performance indexes of IRGS are studied.The principle and functional requirement of IRGS are analyzed,integrated with the proportion guidance law.The major index classification,as the core of optical system and inertial stabilization,is presented.The classification includes nine specific indexes within the two types.Combined with the atmospheric attenuation property and the IR radiation characteristic of remote targets,the specific design methods of the focal length,the clear aperture and the field of view of optical system are given.With the searching blind regions,the image motion changes,the maximum line-of-sight(LOS)rate and the real time performance of tracking algorithm as constraint conditions,the specific design methods of the searching speed,the stabilization precision,the maximum tracking speed and the angle tracking precision are acquired.3.The influence of missile attitude motion on IR imaging system is studied.The relational expressions between the missile attitude motion and the image motion changes of the IR detector are established based on the geometric optical theory.The influence laws of missile attitude motion on image motion are obtained.Then,with the spatial resolution,the temperature resolution,the modulation transfer function and NIIRS as the evaluation indexes,the constraint conditions for IRGS stabilization precision are given.4.The theoretical model and original errors of transient pointing error are studied.Starting with the characteristics of system structure,the theory model of LOS rate error is established.The strategy to acquire LOS rate is described based on servo control circuit.The measurement equations of LOS rate are derived by means of coordinate transformation.Error model is then obtained with the help of differentiation method.Influence factors are discussed in detail for error analysis,mainly including gyroscope error,angle error in process of coordinate transformation and mechanical installation error.Each error is determined by the transfer function of control.Error measurement for an IRGS prototype is carried out,showing that the LOS rate error can be predicted accurately.The theoretical model can be used for key part selection and accuracy allocation.With the reasonable design of IRGS,the LOS rate accuracy is 0.10°/s and 0.28°/s as the LOS rate is less than 1.5°/s and 6°/s,respectively.5.In order to meet the application requirement of lightweight and miniaturization,the design method of IR imaging system with the characteristics of large relative aperture and compact structure is studied.Based on the comparison of different optical structures and features,the two-lens telephoto structure merely using aluminum alloy as the housing material is adopted.By balancing the thermal drift of refraction index and the geometrical change,an athermalized lens with the focal length is 90 mm and F number 1.2 is achieved.The whole optical length is 75 mm and the weight is only 234 g.The optical-structure-thermal integrated analysis is completed and experiment is carried out.Results showed that the lens can remain fine imaging quality under temperature range from-40 oC to 60 oC,which is beneficial to the lightweight design of IRGS.6.The IRGS prototype is manufactured and the experiment is carried out.