Transportation by Multiple Mobile Manipulators in Unknown Environments With Obstacles

A novel approach to transport a large object by multiple mobile manipulators in unknown environments with obstacles is proposed in this paper. The main moving direction of the system as well as its width and the leading mobile manipulator are first assigned manually or obtained automatically according to the geometric layout of mobile manipulators. Then, three transportation modes, i.e., default mode, shrink mode, and incline mode, are defined based on constraints from the object and mobile manipulators. In default mode, mobile manipulators are distributed around the object to be transported with the initial geometric layout. Mobile manipulators in shrink mode are required to lie inside the boundaries of the object's outlined rectangle, whereas multiple mobile manipulators in incline mode endeavor to hold the object with an inclined angle. On this basis, a decision based on the multiscale passageway is proposed to facilitate the selection of best transportation mode and moving direction. The effectiveness of the approach is verified by simulations and experiments.