Near space interception of ballistic missiles during boost phase

A near optimal guidance law for an interceptor that impacts the ballistic missile in near space is presented in this paper. The interception issue is casted as an optimal control issue with optimal estimate of the interceptor's reference trajectory. A higher-order polynomial that satisfies all the initial and final conditions is used to approximate the near optimal trajectory. The near-optimal guidance trajectory is fed back into the control system of the interceptor and is refined when the information is updated. It can be adjusted by changing the final conditions or the interception time. Then a compound performance index is given to determine the uncertain parameters. By minimizing the performance index the optimal value of all parameters can be obtained and the intercept geometry can be easily controlled. Then the control vectors can be obtained by discretization. Simulation results show the effectiveness of the proposed guidance law.