Rearrangement Task by Multiple Mobile Robots With Efficient Calculation of Task Constraints

We address multiple-robot rearrangement problems in this paper. The rearrangement of multiple objects is a fundamental problem involved in numerous applications. In this case, it must be considered that a rearrangement task has constraints regarding the order of the start, grasping and finish time of transportation. Attention to these constraints makes it possible to rearrange rapidly; however, the calculation of the constraints is costly in terms of computation. In this paper, we propose a rearrangement method that calculates constraints efficiently. We analyze constraints and classify them into two groups: those that require less computational cost and those that require more. Robots do not calculate all groups at the same time — the time required for each type of calculation varies. The proposed method is tested in a simulated environment 96 times in six kinds of working environments with up to four mobile robots. Compared to the method that calculates all constraints at the same time, the robots' inactive time is significantly reduced and the total time for task completion is also eventually reduced. The proposed method is incomplete, but can be used to perform most rearrangement problems in a short time.