  Multi-vehicle coordinated motion planning has always been challenged to
safely and efficiently resolve conflicts under non-holonomic dynamic
constraints. Constructing spatial-temporal corridors for multi-vehicle can
decouple the high-dimensional conflicts and further reduce the difficulty of
obtaining feasible trajectories. Therefore, this paper proposes a novel
hierarchical method based on interactive spatio-temporal corridors (ISTCs). In
the first layer, based on the initial guidance trajectories, Mixed Integer
Quadratic Programming is designed to construct ISTCs capable of resolving
conflicts in generic multi-vehicle scenarios. And then in the second layer,
Non-Linear Programming is settled to generate in-corridor trajectories that
satisfy the vehicle dynamics. By introducing ISTCs, the multi-vehicle
coordinated motion planning problem is able to be decoupled into single-vehicle
trajectory optimization problems, which greatly decentralizes the computational
pressure and has great potential for real-world applications. Besides, the
proposed method searches for feasible solutions in the 3-D $(x,y,t)$
configuration space, preserving more possibilities than the traditional
velocity-path decoupling method. Simulated experiments in unsignalized
intersection and challenging dense scenarios have been conduced to verify the
feasibility and adaptability of the proposed framework.
