Abstract: An online trajectory planning algorithm based on dynamic inversion in the virtual domain(IDVD) is proposed for the online rapid planning of midcourse guidance trajectory of interceptor missile that meets multiple constraints. The virtual factors are introduced to transfer the discrete state variables from the time domain to the virtual domain. Based on the idea of dynamic inversion，the virtual arc length is used to obtain the high-order derivative of the boundary conditions，which improves the computational efficiency. A penalty function for process constraints is constructed to plan the guidance trajectory with the performance indicators so that the trajectory can meet multiple constraints in the time domain. Finally，an on-line re-planning strategy after updating the target information is presented based on the proposed algorithm.The simulated results show that, although the proposed algorithm can quickly generate a reference trajectory that satisfies multiple constraints，it has good real-time performance and robustness，and is suitable for solving on-line rapid trajectory planning problems.

Key words: interceptor, midcourseguidancetrajectory, multipleconstraint, on-linerapidplanning, inversedynamicsinthevirtualdomain