Controller and method for transporting devices

A storage system comprising:

• a first set of parallel rails or tracks extending in an X-direction, and a second set of parallel rails or tracks extending in a Y-direction transverse to the first set in a substantially horizontal plane to form a grid pattern having a plurality of grid spaces;
• a plurality of stacks of containers located beneath the rails, and arranged such that each stack is located within a footprint of a single grid space;
• a multiplicity of load handling devices, each load handling device configured to selectively move laterally in the X and Y directions, above the stacks on the rails;
• and
• a controller having:
• a route determination unit configured to determine a route from one location on the grid-like structure to another location on the grid-like structure for each load handling device;
• a clearance unit configured to provide clearance for each load handling device to traverse a portion of the determined route;
• a constraint area determination unit configured to determine a plurality of constraint areas based on static loading, dynamic loading and/or shear loading of the grid-like structure;
• and
• a calculation unit configured to calculate a constraint limit in each constraint area,
• wherein at least one of:
• the clearance unit is configured to grant or withhold clearance to a load handling device to traverse a portion of the determined route based on the calculated constraint limit in the particular constraint area, and
• the route determination unit is configured to determine a route for a load handling device from one location to another location traversing or not traversing a particular constraint area based on the calculated constraint limit in the particular constraint area.

A method of controlling movement of a plurality of transporting devices, the plurality of transporting devices configured to transport containers, the containers being stored in a facility, the facility configured to store the containers in a plurality of stacks, the facility including a plurality of pathways arranged in cells so as to form a grid-like structure above the stacks, wherein the grid-like structure extends in a first direction and in a second direction, the plurality of transporting devices configured to operate on the grid-like structure, the method comprising the steps of:

• determining a plurality of constraint areas based on static loading, dynamic loading and/or shear loading of the grid-like structure;
• and
• calculating a constraint limit in each constraint area;
• determining a route for each transporting device from one location on the grid-like structure to another location on the grid-like structure traversing or not traversing a particular constraint area;
• and
• granting or withholding clearance to each transporting device to traverse a portion of a determined route,
• wherein at least one of the determining a route step or the clearance step is based on the calculated constraint limit in the particular constraint area.