Stop-N-Go: Search-based Conflict Resolution for Motion Planning of Multiple Robotic Manipulators

TL;DR

This paper introduces a search-based conflict resolution method for multi-robot motion planning that inserts pauses into trajectories to resolve conflicts and improve success rates in crowded environments.

Contribution

It proposes a novel conflict resolution approach using A* search to insert pauses, enabling scalable and effective multi-robot motion planning in complex environments.

Findings

Successfully solves challenging multi-robot planning instances

Outperforms baseline methods in feasibility and efficiency

Effectively handles blocked goal positions

Abstract

We address the motion planning problem for multiple robotic manipulators in packed environments where shared workspace can result in goal positions occupied or blocked by other robots unless those other robots move away to make the goal positions free. While planning in a coupled configuration space (C-space) is straightforward, it struggles to scale with the number of robots and often fails to find solutions. Decoupled planning is faster but frequently leads to conflicts between trajectories. We propose a conflict resolution approach that inserts pauses into individually planned trajectories using an A* search strategy to minimize the makespan--the total time until all robots complete their tasks. This method allows some robots to stop, enabling others to move without collisions, and maintains short distances in the C-space. It also effectively handles cases where goal positions are initially blocked by other robots. Experimental results show that our method successfully solves challenging instances where baseline methods fail to find feasible solutions.