Safe and Distributed Multi-Agent Motion Planning under Minimum Speed Constraints

The motion planning problem for multiple unstoppable agents is of interest in many robotics applications, for example, autonomous traffic management for multiple fixed-wing aircraft. Unfortunately, many of the existing algorithms cannot provide safety for such agents, because they require the agents to be able to brake to a complete stop for safety and feasibility insurance. In this paper, we present a distributed multi-agent motion planner that guarantees collision avoidance and persistent feasibility, which can be applied to a team of homogeneous mobile vehicles that cannot stop. The planner is built on top of the idea that a collision-free trajectory in form of a loop can safely accommodate multiple unstoppable agents, while avoiding collisions among them and static obstacles. At every time step, in a distributed manner, the agents generate trajectory-manipulating actions that preserve the loop structure. Then, a deconfliction process selects a conflict-free subset of the generated actions, which are applied at the next time step. Through simulation using an unstoppable Dubins car model, we show that the proposed motion planner is able to provide persistent safety guarantees for such agents in obstacle-cluttered space in real-time.