Complete Decentralized Method for On-Line Multi-Robot Trajectory Planning in Valid Infrastructures

TL;DR

This paper introduces a complete decentralized method for online multi-robot trajectory planning in valid infrastructures, guaranteeing collision-free paths with quadratic time complexity, and demonstrating significant efficiency improvements over local collision avoidance methods.

Contribution

The paper presents a novel decentralized trajectory planning approach that guarantees success in valid infrastructures and outperforms reactive methods in speed and deadlock avoidance.

Findings

Guaranteed collision-free trajectories in valid infrastructures.

Quadratic time complexity in the number of robots.

Up to 48% faster trajectories compared to local collision avoidance.

Abstract

We consider a system consisting of multiple mobile robots in which the user can at any time issue relocation tasks ordering one of the robots to move from its current location to a given destination location. In this paper, we deal with the problem of finding a trajectory for each such relocation task that avoids collisions with other robots. The chosen robot plans its trajectory so as to avoid collision with other robots executing tasks that were issued earlier. We prove that if all possible destinations of the relocation tasks satisfy so-called valid infrastructure property, then this mechanism is guaranteed to always succeed and provide a trajectory for the robot that reaches the destination without colliding with any other robot. The time-complexity of the approach on a fixed space-time discretization is only quadratic in the number of robots. We demonstrate the applicability of the presented method on several real-world maps and compare its performance against a popular reactive approach that attempts to solve the collisions locally. Besides being dead-lock free, the presented approach generates trajectories that are significantly faster (up to 48% improvement) than the trajectories resulting from local collision avoidance.