🤖 AI Summary
This work addresses the challenge of simultaneously achieving path optimality and kinematic feasibility in multi-agent motion planning by proposing a two-stage framework. It first generates initial collision-free paths using Conflict-Based Search (CBS) or Priority-Based Search (PBS), then refines them through a multi-phase optimal control problem (OCP) formulation. A motion primitive generation mechanism is introduced to enforce uniform sampling time constraints. Additionally, the SIPP-IP algorithm is extended to accommodate general cost functions and large-footprint agents. Experimental results demonstrate that, in trailer-truck systems, lattice-based planners outperform the extended SIPP-IP due to less conservative collision checking. In cluttered environments, CBS yields higher success rates and lower computation times than PBS, though both approaches produce solutions of comparable quality after optimization.
📝 Abstract
Multi-agent motion planning (MAMP) is an important problem for autonomous systems with multiple agents. In this work we propose a two-step method for finding optimized and kinematically feasible solutions to MAMP problems. The first step finds an initial feasible solution using state-of-the-art methods such as conflict-based search (CBS) or priority-based search (PBS), and the second step is an improvement step which improves the solution by solving a multi-phase optimal control problem (OCP) where the initial solution is used to warm-start the solver. We also propose a method for generating motion primitives in an optimized way under the constraint that the primitive durations are all multiples of the same sample time.
We evaluate our proposed framework on a MAMP problem for tractor-trailer systems. We extend the safe interval path planning with interval projections (SIPP-IP) algorithm so it can handle more general cost functions and larger agents, but our results show that for the tractor-trailer system a simple lattice-based planner performs better due to less conservative collision checks. Our experiments also indicate that CBS performs better than PBS for this system as it achieves a higher success rate in environments with obstacles and had a lower average runtime, although both planners achieve solutions of similar quality after the improvement step.