A novel motion coordination method for variable-sized multi-mobile robots

Multi-mobile robot systems (MMRSs) are widely used for transportation in industrial scenes such as manufacturing and warehousing. In an MMRS, motion coordination is important as collisions and deadlocks may lead to losses or system stagnation. However, in some scenarios, robot sizes are different when loaded and unloaded, which means that the robots are variable-sized, making motion coordination more difficult. The methods based on zone control need to first divide the environment into disjoint zones, and then allocate the zones statically or dynamically for motion coordination. The zone-control-based methods are not accurate enough for variable-sized multi-mobile robots and reduce the efficiency of the system. This paper describes a motion coordination method based on glued nodes, which can dynamically avoid collisions and deadlocks according to the roadmap structure and the real-time paths of robots. Dynamic features make this method directly applicable to various scenarios, instead of dividing a roadmap into disjoint zones. The proposed method has been applied to many industrial projects, and this study is based on some manufacturing projects for experiments. Theoretical analysis and experimental results show that the proposed algorithm is effective and efficient.