Line-of-sight Rate Estimation Research Articles

Design of Integrated Guidance and Control Law with LOS Rate Estimate Based on UKF

The traditional way to design a guidance and control system of a missile is to form subsystems separately, with disadvantages of lack of cooperation between subsystems. A homing missile with a strapdown seeker was discussed, and an integrated guidance and control (IGC) model in vertical plane has been formulated. A scheme of IGC law based on sliding mode control (SMC), using the line of sight (LOS) rate estimated by Unscented Kalman Filter (UKF) from the strapdown seeker was proposed. In addition, to verify the effectiveness of the IGC law based on SMC with LOS rate estimation by UKF algorithm, a numerical simulation by MATLAB was made. The simulation results demonstrated that the flight attitude was in stability and the missile was able to hit the target with a small miss distance.

Line-of-Sight Rate Estimation Based on UKF for Strapdown Seeker

Aiming at the problem that the strapdown imaging seeker cannot measure line-of-sight (LOS) rate directly, this paper presents an effective algorithm for LOS rate estimation. To address the problem, the reference frames and angles are defined. According to the relative kinematics and attitude relationship between missile and target, the nonlinear state equations and measurement equations of LOS rate are derived, and the estimation algorithm based on unscented Kalman filter (UKF) is proposed. Considering the estimation accuracy mainly depends on body LOS (BLOS) angle accuracy and gyro accuracy, the paper is unprecedented to research how these two factors impact the LOS angle and rate accuracy by simulation. Semiphysical simulation experiment verifies the correctness and accuracy of the algorithm, and the result shows that the estimation algorithm can meet the accuracy and real-time requirements of guidance system simultaneously. Thus LOS rate estimation algorithm based on UKF provides a theoretical basis for engineering applications of strapdown imaging seeker.

A Novel Decoupled LOS Rate Estimator for Terminal Guidance

An novel decoupled estimation algorithm based on kalman filter is presented to solve the line-of-sight (LOS) rate estimation problem in terminal guidance of air-to-air combat. The measurements of target azimuth and elevation are obtained by missile-borne active radar seeker which use a monopulse doppler radar. As it cant be directly measured by this kind of radar, the LOS rate which is needed as the input of guidance law should be estimated from these angle measurements. The close-loop simulation of LOS rate estimation in typical terminal guidance scenario that an air-to-air missile seeks a military fighter validates the presented algorithm.

A Novel Decoupled LOS Rate Estimator for Terminal Guidance

An novel decoupled estimation algorithm based on kalman filter is presented to solve the line-of-sight (LOS) rate estimation problem in terminal guidance of air-to-air combat. The measurements of target azimuth and elevation are obtained by missile-borne active radar seeker which use a monopulse doppler radar. As it cant be directly measured by this kind of radar, the LOS rate which is needed as the input of guidance law should be estimated from these angle measurements. The close-loop simulation of LOS rate estimation in typical terminal guidance scenario that an air-to-air missile seeks a military fighter validates the presented algorithm.

Estimation of LOS Rates for Target Tracking Problems using EKF and UKF Algorithms- a Comparative Study

One of the most important problem in target tracking is Line Of Sight (LOS) rate estimation for using from PN (proportional navigation) guidance law. This paper deals on estimation of position and LOS rates of target with respect to the pursuer from available noisy RF seeker and tracker measurements. Due to many important for exact estimation on tracking problems must target position and Line Of Sight rates estimated with least error rather than actual values. In this paper extended Kalman filter (EKF) and unscented Kalman filter (UKF) algorithms are used for estimation of target position in three-dimensional (3-D) and LOS rates in elevation and azimuth for seekers and trackers. For comparison of algorithms, model of the system simulated using MATLAB and many tests were carried out. Simulation experiments show that the efficiency of EKF due to least RMSE has better performance. However, the performance of EKF algorithm has been dramatically decreased when initializations (initial state assumption) are not near to real values, which in this condition UKF method provides a more accurate approximation. Numerical results from simulations show that the UKF is robust against uncertainties and has better state estimation accuracy. Therefore, UKF algorithm is appropriate, and it can run on target tracking systems

공분산 및 신호관리를 이용한 RF탐색기 시선각 변화율 추정기법

The line-of-sight(LOS) rate is estimated using Kalman filter in Radio-Frequency(RF) seeker. For the two axis gimbaled seeker, proper system modeling is considered and the basic filter structure is set up. The main issue for Kalman filter is choosing the proper process and measurement noise. For the measurement process, the signal to noise ratio(SNR) and other components are introduced. To cope with the eclipse problem or other abnormal seeker status, the pseudo input signal concept is proposed. By conditioning abnormal signals, the LOS rate estimation performance is increased. The process noise is also an important factor in the propagation phase. The analytical approach on a process noise component is performed and a reliable region for the filter is calculated based on the eigenvalue analysis. Some numerical simulations are performed to check the validity of suggested algorithm.

Synthetic-Waypoint Guidance Algorithm for Following a Desired Flight Trajectory

Synthetic-Waypoint Guidance Algorithm for Following a Desired Flight Trajectory

A LOS rate estimation method for bank-to-turn missiles

We compensate for the effect of the fast roll motion of bank-to-turn (BTT) missiles through appropriate coordinate transformation. Thereby, the proposed line-of-sight (LOS) rate estimator can provide better estimation performance than the previously known passive target tracking methods since it is independent of seeker-stabilization loop and robust with the measurement noise.

Miss Distance Error Analysis of Exoatmospheric Interceptors

A miss distance error analysis of exoatmospheric interceptors with liquid divert thrusters in endgame is presented. The analysis relates miss distance uncertainty to 1) infrared/electrooptic seeker noise, 2) seeker latencies caused by image processing and motion compensation and integration to detect the target on the focal plane, 3) seeker scan angle measurement errors of gyro, 4) range error or time-to-go error, and 5) filtration of all these errors through a Kalman filter for estimating the line-of-sight (LOS) rates. With the relationships developed, the missile designer/analyst can predict a probable miss distance with the hardware parameters of the selected divert thrusters and sensor suite, as well as software parameters of the selected guidance policy. The analyst can also arrive at the LOS rate estimation accuracy requirements about the azimuth and elevation axes, to be achieved by a tracking Kalman filter for specified miss distance statistics. The analysis provides insight and predicts reliably the miss distances expected from Monte Carlo simulations and hardware-in-the-loop laboratory tests. I. Introduction M ISS distance error analysis of air missiles seems to be well understood, 1,2 but that of exoatmospheric interceptors equipped with infrared sensors and liquid divert thrusters appears to be lagging behind. To be sure, Refs. 3‐6 provide a system engineer design tools to arrive at hardware/software requirements for exoatmospheric interceptors to meet a specific miss or hit accuracy without the use of an elaborate trajectory simulation. However, these references do not specifically address unique features of exoatmospheric interceptors with liquid propulsion systems. This paper attempts to fill this gap.