An autonomous mobile robot includes a housing mounted on a track and controllable to move along the track and to stop at each selected location, two side covers pivotally mounted on the left and right sides of the housing and movable by a respective driving motor to close/open the left or right side of the housing, and a mechanism controllable to move a material carrier horizontally leftwards or rightwards to the outside of the housing after opening of the left-sided or right-sided side cover.