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.