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Optimal Launch Time Selection in Target-Missile-Defender Scenario

This paper proposes a novel launch strategy to deal with the problem of active aircraft protection, where an aircraft (target) actively launches a defensive missile (defender) to intercept an attacking missile (attacker). The attacker is assumed to pursue the target aircraft by employing a known linear guidance law, and the defender is chasing the attacker using the proportional navigation-based guidance laws or the predictive guidance law after launch. Regarding the defender using proportional navigation-based guidance law, a piecewise-nonlinear guidance model is established considering the launch time of the defender as the control input. The defender’s launching envelope and optimal launch time are derived through online optimization, by considering the control effort as the performance index. As to the defender employing the predictive guidance law, the problem of solving the optimal launch time is converted into an equivalent parameter optimization, and the optimal launch situation is obtained from a geometric perspective. Numerical simulations in different scenarios validate the algorithm to be effective, and demonstrate that the proposed strategy can accomplish successful interceptions under more scenarios than before. The guidance commands and control effort of the defender are adequately reduced through optimal launch time.