Methods, systems and apparatus for controlling movement of transporting devices

A method for controlling movement of at least one transporting device arranged to transport at least one container, the method comprising:

• determining, by one or more processors, a plurality of paths for a plurality of transporting devices to travel on pathways of a facility so that no two of the plurality of transporting devices have locations while traveling along the plurality of paths that would cause the plurality of transporting devices to overlap at a same time, the plurality of paths comprising a first path for traveling by a first transporting device of the plurality of transporting devices and a second path for traveling by a second transporting device of the plurality of transporting devices,
• wherein the pathways form a grid-like structure above a plurality of containers arranged within the facility, the pathways comprising a first set of parallel rails extending in a first direction and a second set of parallel rails extending in a second direction transverse to the first direction in a substantially horizontal plane, at least some of the plurality of containers being stored in stacks,
• wherein the plurality of transporting devices are configured to selectively move laterally in the first direction and the second direction on the pathways, at least some of the plurality of transporting devices being configured to transport the plurality of containers;
• generating, by the one or more processors, a plurality of clearance commands for the plurality of transporting devices to cause the plurality of transporting devices to travel on the pathways along portions of the plurality of paths, the plurality of clearance commands comprising a first clearance command for the first transporting device;
• determining, by the one or more processors, there is a potential for a collision between the first transporting device traveling along the first path and the second transporting device traveling along the second path;
• in response to determining that there is the potential for the collision:
• withholding, by the one or more processors, a second clearance command for the first transporting device that would cause the first transporting device to travel on the pathways along a portion of the first path,
• determining, by the one or more processors, a revised path different from the first path for the first transporting device to travel on the pathways, and
• generating, by the one or more processors, a third clearance command for the first transporting device to cause the first transporting device to travel on the pathways along a portion of the revised path;
• and
• storing the plurality of clearance commands and the third clearance command to a memory device.