具有终端角度约束的H_∞制导律设计

针对导弹对地面运动目标精确攻击时姿态约束的H_∞末制导问题,提出了一种新的具有终端角度约束的制导律.基于二维弹目相对运动学的非线性关系,并将目标机动运动和系统结构摄动作为外部的扰动,建立了垂直平面内弹目相对运动的数学模型.以命中点终端姿态角跟踪误差和控制能量最小为性能指标,同时基于零化弹目视线角速率的思想, 设计得到了非线性H_∞鲁棒制导律.该方法利用Lyapunov稳定理论严格证明了制导系统的全局渐近稳定性,而非求解HJI偏微分方程,同时也避免了对剩余时间的估计.数字仿真表明这种制导律在不需要任何目标运动信息的情况下,仍然保证终端角度和制导精度的要求,具有很强的鲁棒性和适应性.

Design of H_∞ Guidance Law with Terminal Angle Constraint

According to the problem of terminal guidance for air-to-ground missile in vertical plane with impact angle constraint, a new continuous nonlinear guidance law with robustness is proposed. Target acceleration and system perturbation are regarded as an exogenous disturbance, the mathematic dynamic model is bult acoording to two-dimensional relationship between missile and target. Based on the performance index of minimizing the terminal angular constraint tracking error and the method of zeroing the rate of line-of-sight (LOS) angle, a nonlinear control strategy is contrived to obtain the continuous nonlinear guidance law. The asymptotic stability of guidance system is strictly proven by Lyapunov stability theory instead of solving the Hamilton-Jacobi-Isaacs (HJI) partial differential equation, at the same time avoiding the estimation of the time-to-go. Finally simulation results show that the guidance law is more robust and both the impact angle and guidance precision are met in the case of no any target information.The proposed method is simple, so it is convenient for comprehension and practical implementation.