Guidance Law For Penetrating Laser Guided Bomb

In recent years, local wars have shown the early general aerial bombs flying distance is limited, the attack precision and effect are all poor, obviously lag behind the requirements of modern warfare. The penetrating Laser Guided Bomb (LGB) is one kind new bomb with precision strike and thorough destruction capabilities. It has the following characteristics. First, its trajectory range is far. Second, its miss-distance is small. Third, its terminal velocity angle is large and angle-of-attack is small, the penetrating ability is strong. In order to achieve the above three goals, this article analysis the entire flight trajectory of LGB to proposed feasible guidance laws.Based on the force and moments analyzing, the motion equations are established in inertial coordinate system. On the assumption that small disturbance and LGB is axisymmetric, the LGB motion was decoupled into roll, pitch and yaw three independent loops.As the detecting distance of LGB seeker is limited, the trajectory between bomb-dropped and target-taking is named middle course guidance, while catching the target, called terminal guidance. During the middle course guidance, the LGB flies according to a scheduled angle-of-attack, called plan trajectory. And because of the constrained laser seeker gimbal angle, a transition trajectory is designed for the hand over of middle course guidance and terminal guidance. The simulation result show the plan trajectory can improve the LGB flying range, the transition trajectory satisfy the requirement of gimbal.During the terminal guidance, considering the states motion character of sliding mode control we design Sliding Mode Guidance law (SMG) to achieve penetrating attack in the pitch loop, the stability of SMG has been proved also. The commonly used Proportional Navigation Guidance law (PNG) is using in the yaw loop duiring terminal guidance. The simulation results show the terminal guidance laws can meet the demand of miss-distance and penetrating attack.Overload tracking controllers were designed based on classical PID design method for the entire trajectory simulation. In the entire trajectory simulation, all error sources have been considered. The impact of the wind is worth attention, so we establish a wind disturbance model and analyze the wind impact to trajectory. A typical entire trajectory simulation is given to show the miss-distance, terminal angle-of-attack and terminal velocity angle are satisfied the requirements. And the design of plan trajectory, transition trajectory and the SMG for terminal guidance are all available.