pc-dbCBS: Kinodynamic Motion Planning of Physically-Coupled Robot Teams

-- Motion planning problems for physically-coupled multi-robot systems in cluttered environments are challenging due to their high dimensionality. We propose Physically-coupled discontinuity-bounded Conflict-Based Search (pc-dbCBS), an anytime kinodynamic motion planner, that extends discontinuity-bounded CBS to rigidly-coupled systems. Our approach proposes a tri-level conflict detection and resolution framework that includes the physical coupling between the robots. Moreover, pc-dbCBS alternates iteratively between state space representations, thereby preserving probabilistic completeness and asymptotic optimality while relying only on single-robot motion primitives. Across 25 simulated and six real-world problems involving multirotors carrying a cable-suspended payload and differential-drive robots linked by rigid rods, pc-dbCBS solves up to 92% more instances than a state-of-the-art baseline and plans trajectories that are 50-60% faster while reducing planning time by an order of magnitude. Physically-coupled systems, such as multirotors collabora-tively transporting cable-suspended payloads [1] or multiple mobile manipulators transporting objects [2], are increasingly used in real-world tasks requiring coordinated interaction. These systems are particularly valuable in environments such as construction sites for carrying tools or materials and in precision tasks requiring synchronized motion. The robot coupling introduces additional challenges, as the planned motions must respect both inter-robot dependencies and the system's dynamic constraints. There has been a significant focus on controlling such systems [3, 4] and only limited work on planning feasible motions in cluttered environments that require team formation changes. Moreover, existing planners produce motions that are rather slow and fail to exploit the agility of the underlying single-robot systems.