Roll-pitch Seeker Research Articles

Research on the Influence of the Disturbance Rejection Rate of a Roll–Pitch Seeker on Stable Tracking Characteristics

The disturbance rejection rate (DRR) is an inherent problem of the seeker. The additional line-of-sight (LOS) angular velocity information of the seeker caused by the DRR will affect the attitude of the aircraft through the guidance system, thus forming a parasitic loop in the guidance and control system of the aircraft, which has a great influence on the guidance accuracy. In this study, the influence of the DRR of the roll–pitch seeker on the stable tracking of a maneuvering target is explored. First, the tracking principle of the roll–pitch seeker is analyzed and the conditions for completely isolating the disturbance of the aircraft attitude are deduced. Then, the expression of the frame error angle is derived, a semi-strap-down stable control closed-loop scheme is established, and the DRR transfer function is derived by adding different disturbance torque models. Finally, the simulation of stability tracking characteristics is carried out. The results show that when the aircraft attitude is disturbed at a low frequency or the target is maneuvering at a low frequency, the DRR caused by the spring torque has a great influence on the tracking angle of the two frames, the line of-sight rate accuracy of the optical axis output and the detector error angle. On the contrary, the damping torque DRR plays a leading role in tracking accuracy.

Research on the Influence of the Parasitic Loop of the Roll-Pitch Seeker on the Stability of the Guidance System

Disturbance rejection rate is an important performance index of the seeker,the disturbance rejection rate affects the extraction accuracy of the line-of-sight angular velocity output by the seeker,and introduce an additional parasitic loop in the guidance loop,this loop affects the stability of the guidance system and reduces the accuracy of the missile guidance system. This paper analyzes the extraction principle of the line-of-sight angular velocity of the roll-pitch seeker,the parasitic loop model of the roll-pitch seeker caused by the scale deviation between the detector, the frame angle sensor and the angular rate gyroscope is established, and the stability and time domain response characteristics of the parasitic loop are analyzed. Then, based on the time-invariant theory, the influence of the parasitic loop of the roll-pitch seeker on the stability of the guidance system and the guidance parameters is analyzed.The simulation results show that the positive and negative feedback characteristics of the disturbance rejection rate parasitic loop have a great influence on the stability of the guidance system. It is necessary to design appropriate guidance parameters according to the characteristics of the parasitic loop to meet the guidance accuracy requirements.

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.

Research on Command Generation Strategy of Roll and pitch seeker

The roll pitch seeker has a large field of view, which can achieve large off-axis angle attacks. At the same time, it has a simple structure and is easy to miniaturize, which is beneficial to the overall design of the missile. However, the over-tracking problem of the rolling seeker restricts her application in engineering. To solve this problem, this paper proposes a method to calculate the roll frame angle by using the angular rate of the projectile line of sight when the pitch frame angle is small. The simulation results show that this method is effective in the overhead tracking control.

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. Co-ordinate 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 roll-pitch seeker under the anti-infrared decoy state is effective.

A New Compensation Method for DRR of a Roll-Pitch Seeker Based on ESO

We propose a new DRR (Disturbance Rejection Rate) compensation method of a roll-pitch seeker based on ESO (extended state observer). The characteristics of a roll-pitch seeker and the DRR definition of two frames of a roll-pitch seeker are analyzed. The influence of different interference torques and different frequency bandwidths on the compensation effect is analyzed. Modeling and simulation of the guidance system of a roll-pitch seeker with the parasitic loop of DRR are carried out. Influence of the new DRR compensation method on dimensionless miss distance is analyzed. Mathematical simulation is established to compare the new ESO-based DRR compensation method with the existing methods such as the feedforward method and Kalman filter method. The analysis and simulation results show that the new ESO-based DRR compensation method has the advantages of high precision, good applicability, and easy adjustment, and the new method can effectively reduce the dimensionless miss distance with different types of input errors. The research of this proposed new method can provide a reference for the latest generation air-to-air missile operations in a high-altitude and high-speed environment and the high-precision research of a roll-pitch seeker.

Predictive Functional Control-Based Zenith Pass Controller Design for Roll-Pitch Seeker

A roll-pitch seeker has a wide field of view but suffers from a singularity as the sightline coincides with the outer gimbal (OG) axis. In the vicinity of the singularity, the tracking effectiveness is often degraded or even lost due to the high actuation demand on OG, which is known as the zenith pass problem. To solve this problem, this paper first proposes a novel motion model of sightline to predict the singularity in a receding horizon, where the model parameters are identified using a modified recursive least square estimator. And with the singularity predictions as set points, a predictive functional controller is then designed for the OG position control to minimize the tracking error. This novel combination control scheme is validated in MATLAB/Simulink. Simulation results have confirmed that the proposed scheme can significantly mitigate the zenith pass problem and be applied to the real-time tracking process.

Line-of-sight stabilization of roll-pitch seeker using differentiator-based disturbance compensation control

A new control problem of roll-pitch seeker about the disturbance coupling is investigated in this work. Previous control strategies of roll-pitch seeker rarely considered the effects of the dynamic coupling disturbances from the missile angular motion, and because of the polar coordinate structure, the disturbance rejection strategies of yaw-pitch seeker cannot be utilized directly on roll-pitch seeker. Thus this article presents a new control strategy to improve the disturbance rejection ability of roll-pitch seeker. To analyze the disturbance coupling problem, the roll-pitch seeker model is derived with consideration of the missile body angular motion and torque disturbances. The motion equation of roll-pitch seeker shows that part of the dynamic coupling disturbance can be eliminated by certain choices of inertial parameters. The rest of disturbance is reduced by the stabilization loops using a differentiator-based disturbance compensation controller. Particularly, a missile body angular acceleration estimation method is designed for the compensator based on an adaptive differentiator. In addition, comparisons with other control strategies are carried out via numerical simulations, and the results confirm the effectiveness of the proposed method.

A line-of-sight rate estimation method for roll-pitch gimballed infrared seeker

Roll-pitch gimballed infrared seeker has wide field of view but suffers from the rapid roll motion of the zenith-pass problem. For estimating the line-of-sight (LOS) rate with the roll-pitch seeker, we propose a coordinate transformation method to compensate for the impact of rapid roll motion. A precise LOS rate dynamics model is derived on the transformed coordinate system. And based on the model, we design a novel LOS rate estimator with the Improved Iterated Cubature Kalman Filter algorithm (IICKF). The proposed IICKF is derived from reducing the dimensionality of the optimization problem of the ICKF, which inherits the estimation accuracy but decreases the computational complexity of the algorithm. For validating, Monte Carlo simulations are performed at last. The simulation results show that the proposed LOS rate estimator outperform the standard EKF, CKF, ICKF, and can well cope with the rapid roll motion of the zenith-pass problem in roll-pitch gimballed infrared seeker system.

滚仰式导引头跟踪回路角增量优化

A method to generate and optimize angle increments was put forward to extract the tracking loop instruction of a roll-pitch seeker. Firstly, one kind of the roll-pitch seeker was introduced, and its mechanical construction and operation principle were given. Then, the angle increments of roll gimbals and pitch gimbals were calculated based on the target deviation on the image plane and the optical focal length. Both roll gimbal instruction and pitch gimbal instruction were calibrated to be absolute angular position instructions from the zero position respectively. The absolute angular position instruction for the pitch gimbals was calibrated to be from zero to /2, while that for the roll gimbals was calibrated to be from zero to 2. According to the principle of minimizing the angle increment of roll gimbals as small as possible, four different optimized control strategies were designed. On the basis of mentioned strategies, the feedback roll gimbal angle was separated into four quadrants. Finally, a simulation and a test were implemented to check the validity of the presented algorithm. Results show that the submitted generation and optimization of angle increments for roll-pitch seekers perform effectively and the tracking error is less than 0.15.

LOS Stabilization and Gyro Configuration Analysis for Roll-Pitch Seeker

Roll-pitch seeker is currently applied in particular missiles, especially in air to air missiles. A representation of the seeker gimbal forward kinematics is analysed for the roll-pitch seeker based on the product-of-exponentials (POE) formula. And by transforming the inertial angular rate into the line-of-sight (LOS) coordinate system with the aid of recursive angular velocity equations, the LOS stabilization equation is obtained, then various schemes of gyroscope configuration and control are put forward based on the gyro direct stabilization. The research provides theoretical basis for the LOS stabilization control to isolate the LOS from the disturbance and vibration of carrier.