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She H.-P.,Beijing Institute of Technology | Ni H.,Science Research Institute of China North Group Company
Journal of Beijing Institute of Technology (English Edition) | Year: 2011

The precise target location needs to be loaded before the airborne satellite-guided bomb launch from the aircraft for attacking the target accurately. In the traditional method, the laser range finder and the angle sensors of the optical pod/airborne radar were used to measure the relative distance and angle between the bomb and the target, and the target position can be calculated by these measurements. It is difficult to meet the requirement of high positioning accuracy when launching outside the enemy defense area because of the limited precision of the angle sensors. A new algorithm for target location using distance measurements at different locations is proposed to solve this problem. It is derived from the theoretical formulas, and least squares estimation and iterative method are used for calculation process. Based on this algorithm, only the laser range finder is needed and the angle sensors are not required. Simulation results for a typical example show that, the positioning accuracy for target at the range of 40 km is less than 3 m (CEP), and the convergence rate is fast enough. In addition, the accuracy and convergence rate of the algorithm can be improved by optimization of the aircraft flight path and selection of the positions for measurement. © Copyright. Source


She H.-P.,Beijing Institute of Technology | Yang S.-X.,Beijing Institute of Technology | Ni H.,Science Research Institute of China North Group Company
Binggong Xuebao/Acta Armamentarii | Year: 2011

When GPS/INS guided munition needs in-flight realignment after it is fired from a conventional platform, an initial roll angle is difficult to be acquired. To solve this problem, two new algorithms of initial roll angle were proposed with regard to the non-spin and low-speed spin of projectile. The relationships between the roll angle and the transverse angular rates and attitude angle rates were derived from attitude kinematics equations. The measured values of angular rate gyroscopes and GPS velocity were used to obtain optimal estimation of roll angle based on least squares estimation. Simulation results and performance analysis show that the random and constant wind during flight are the main factors affecting estimation accuracy. The estimated errors are less than 3° under different typical levels of measurement and flight conditions. The algorithm can be used to estimate the roll angle during in-flight coarse alignment. Source


Guo Z.,Beijing Institute of Technology | She H.,Beijing Institute of Technology | Ni H.,Science Research Institute of China North Group Company
Proceedings of the 2015 27th Chinese Control and Decision Conference, CCDC 2015 | Year: 2015

This paper considers the optimal route planning problem for an unmanned aerial vehicle which flies in average wind field with constant altitude and airspeed between two fixed positions. According to characters of the average wind and voyage of the unmanned aerial vehicles, constant wind model and wind model varying with position are presented based on formula from meteorology and function approximation. By defining new Euler angles, kinematic model in arbitrary variable wind fields and equations expressing relation between airspeed and ground speed are derived. If the distance between origin and destination is much larger than minimum turning radius, the turn rate constraint can be neglected. Analytic expressions are developed to solve the problem by calculus of variations. This solution has small calculation quantity, and it can be used to real-time online implementation for the unmanned aerial vehicle. Simulation examples show that it is feasible and effective for optimal route planning. © 2015 IEEE. Source


She H.,Beijing Institute of Technology | Yang S.,Beijing Institute of Technology | Ni H.,Science Research Institute of China North Group Company | Baier H.,TU Munich
International Journal of Computational Intelligence Systems | Year: 2011

State-dependent Riccati equation (SDRE) techniques are rapidly emerging as general design methods for nonlinear controllers. A nonlinear optimal guidance law with impact angle constraint is derived for planar engagements to attack stationary targets. The guidance problem is formulated as an infinite horizon nonlinear regulator problem whose equilibrium state is zero. It is solved by SDRE technique and the state weight matrix is chosen as a function of time-to-go. Performance of the guidance law is tested numerically with different initial firing conditions for a realistic GPS/INS guided artillery rocket model with low available lateral acceleration. A reasonable launch angle is helpful to reduce the control effort, and it is acquired by trajectory optimization using genetic algorithm. Results show negligible errors for miss-distance and the desired impact angle. The proposed guidance law is a choice for the guided artillery rocket. © 2011 Copyright Taylor and Francis Group, LLC. Source


She H.-P.,Beijing Institute of Technology | Guo S.-L.,Beijing Institute of Technology | Yang S.-X.,Beijing Institute of Technology | Ni H.,Science Research Institute of China North Group Company
Journal of Beijing Institute of Technology (English Edition) | Year: 2011

The theorem is proved that the missile trajectory is a circular curve, when the initial guidance condition is satisfied that the difference between line-of-sight angle and trajectory inclination angle is equal to the difference between desired impact angle and line-of-sight angle, and then the proportional navigation guidance (PNG) whose navigation coefficient equals 2 is executed to attack the stationary target. Based on this theorem, a circular trajectory guidance (CTG) law with impact angle constraint is proposed, and the fixed rudder angle method is used to reach the initial guidance condition. The guidance law is used to the guided artillery rocket with limited maneuverability and ballistic trajectory. Simulation results show that the rocket can hit the target at desired impact angle, and the required lateral overloads during guidance phase is relatively small and it match very well with the available lateral overloads. © Copyright. Source

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