Rapid trajectory optimization for cooperative penetration of missile formation based on two-stage RRT-GMP strategy

In order to improve the autonomous flight capability of a missile formation, this paper studies the rapid optimization of a missile formation's trajectory with multi-constraints by considering the cooperative relative motion relationship between missiles and the hard/soft constraints in penetration. In view that the Gauss pseudospectral method (GPM) has difficulties in selecting initial values, and the rapidly-exploring random tree (RRT) obtains flectional and non-optimal results which are difficult to meet the dynamic constraints, a two-stage optimization strategy of RRT and GPM is proposed based on the analyses of GPM's rapidity and initial value selection. The two-stage strategy takes advantage of the whole-space-search ability of RRT to provide initial values for GPM. Meanwhile, the rapidity and optimality of GPM is used to further smooth and optimize the results of RRT. Then several simulations for the flight mode of the "leader-follower" are conducted to demonstrate the effectiveness of the strategy and the effects of different constraints. The simulation results show that the two-stage strategy can rapidly obtain a missile formation's optimal flight trajectory to meet various constraints, and the optimization time by the two-stage strategy is only about 20% of that by GPM alone.