Control methodology of stacker cranes for collision avoidance considering dynamics in a warehouse

We propose a control methodology of stacker cranes to avoid collisions in warehouse environment including the constraint on trajectories caused by dynamics. In a warehouse environment, there are three problems: constraint on trajectories caused by the consideration of dynamics (e.g., vibration control), safety in the case of an emergency stop, and practical calculation time. In the proposed method, the motion is planned through two approaches. In the first, the trajectories of cranes are chosen from candidates that satisfy the constraint on dynamics and checked to determine whether the selected trajectory ensures safety in an emergency. The calculation cost is reduced by confining the candidate trajectories using the characteristic of the number of cranes. If a collision cannot be avoided in the first approach, we adjust the confined candidate trajectories and find a suboptimal trajectory. Measures used in the second approach are to delay the movement of cranes or to generate detours. The simulation results show the effectiveness of the proposed method.