Influence of roll-pitch seeker DRR and parasitic loop on Lyapunov stability of guidance system

This paper focuses on the influence of the disturbance rejection rate(DRR)and parasitic loop parameters on the stability domain of the roll-pitch seeker's guidance system.The DRR models of the roll-pitch seeker caused by different types of disturbance torques and the scale deviation of different sensors are established.The optimal DRR model of the roll-pitch seeker,which contains the scale deviation model,is proposed by formula derivation.The model of the roll-pitch seeker's guidance system is established and equivalently simplified by the dimensionless method.The Lyapunov stability criterion for stability analysis of the guidance system is given by means of the passivity theorem and related definitions and lemmas.A simplified model of the roll-pitch seeker's guidance system,which is suitable for the Lyapunov stability criterion,is established by formula derivation and equivalent transformation.Three conditions that satisfy the Lyapunov stability criterion are obtained.Mathematical simulation with Nyquist plots is used to analyze the influence of different DRR parameters on the stability domain of the roll-pitch seeker's guidance system.Simulation results of this paper can provide reference for the stability analysis of systems related to the roll-pitch seeker.

Modified attitude pursuit guidance law for low-cost missiles using strap-down seekers

Attitude pursuit guidance law is suitable for low cost missiles.A strap-down seeker is used to achieve this guidance law.The additional angles of attack or sideslip caused by wind and by control system are considered as two disturbing factors which make attitude pursuit law impossible.Therefore,general attitude pursuit guidance law did not account for this two disturbing factors,because with those disturbing factors,it is difficult to apply.To solve the problem,the principle of strap-down seeker detecting target is investigated,the mathematical control model is established,then a modified attitude pursuit guidance law which employs the angular correction for those two disturbing factors is presented.It is proved that the modified attitude pursuit guidance law is appropriated to both in the presence of the additional angle of attack or sideslip via the simulations with the mathematical control model and Monte-Carlo method.

Line-of-sight rates extraction of roll-pitch seeker under anti-infrared decoy state

In this paper,the method of extracting guidance information such as the line-of-sight(LOS)rates under the anti-infrared decoy state for the roll-pitch seeker is researched.Coordinate systems which are used to describe the angles transform are defined.The LOS angles reconstruction model of the roll-pitch seeker in inertial space is established.A Kalman filter model for extracting LOS rates of the roll-pitch seeker is proposed.In this model,the target performs constant acceleration(CA)model maneuvers.The error model of LOS rates extraction under infrared decoy state is established.Several existing methods of extracting LOS rates under anti-infrared decoy state are listed in this paper.Different from the existing methods,a novel method that uses extrapolated values of target accelerations as filter measurements is proposed to solve the guidance information extraction problem under the anti-infrared decoy state.Numerical simulations are conducted to verify the effectiveness of the proposed method under different target maneuvering models such as the CA model,the CA extended model and the singer model.The simulation results show that the proposed method of extracting guidance information such as LOS rates for the rollpitch seeker under the anti-infrared decoy state is effective.

滚仰式捷联导引头视线角速度提取技术研究

滚仰式捷联导引头具有很好的应用前景,但在过顶跟踪时提取稳定的视线角速度问题一直没有妥善的解决方法。提出一种利用导引头提供的失调角、框架角及框架角速度等信息构建"虚拟偏仰式导引头"的方法,设计Kalman滤波器对目标垂直视线运动信息进行估计,进而间接提取出视线角速度信息,用于产生制导指令。仿真结果表明,在过顶跟踪时该方法能有效抑制视线角速度抖动,视线角速度精度显著提高。

Coning motion instability of spinning missiles induced by the delay of strap-down seeker

The strap-down seeker,which combines the seeker's and the onboard gyro's measurements to obtain the target information,has been extensively applied by spinning missiles.The response delay of the strap-down seeker,a novel factor that could result in crosscoupling between the acceleration commands in the pitch and yaw channels and subsequently cause the significant deterioration in dynamic stability of the spinning missile equipped with a rate loop,is noted in this paper.The sufficient and necessary stability conditions are also analytically established based on the system equation with complex coefficient,which are further verified by numerical simulations.It could be indicated that the response delay of the strap-down seeker will greatly deteriorate the dynamic stability of the whole guidance system designed by the conventional method.It is also noticed from analysis that the stable region of the combined guidance coefficient is shrunken significantly with the increase of the spinning rate.

Snake-Hot-Eye-Assisted Multi-Process-Fusion Target Tracking Based on a Roll-Pitch Semi-strapdown Infrared Imaging Seeker

Aiming at intercepting large maneuvering targets precisely,the guidance law of advanced self-seeking missiles requires not only inertial line-of-sight(LOS)angular rate but also target maneuvering acceleration.Moreover,the semi-strapdown stabilization platform has lost the ability to measure the inertial LOS angular rate directly,which needs to be extracted by numerical calculation.The differential operation commonly used in traditional methods can magnify the measurement error of the sensor,resulting in insufficient calculation accuracy of the line-of-sight angular rate.By analyzing the mathematical relationship between the missile-target relative motion and the angle tracking system,a multi-process-fusion integrated filter model of relative motion and angle tracking is presented.To overcome the defect that the infrared seeker cannot directly measure the missile-target distance,following the snake-hot-eye visual mechanism,a visual bionic imaging guidance method of estimating the missile-target relative distance from the infrared images is proposed to improve the observability of the filter model.Finally,target-tracking simulations verify that the estimation accuracy of target acceleration is improved by four times.