A control unit is provided to improve positioning of transporting devices to thereby allow transporting devices to be driven at faster speeds and/or accelerations with minimal positional errors allowing for a reduction in the spacing between transporting devices. A control unit is arranged to control movement of at least one transporting device for containers stored in a facility having a plurality of pathways arranged in cells so as to form a grid-like structure above the stacks which extends in a first direction and in a second direction. The control unit includes a receiving unit arranged to receive information from a first sensor mounted on the at least one transporting device, and a calculating unit arranged to calculate a position of the at least one transporting device based on the received information.