Patent ID: 7937289

Claim:
A computer implemented method for monitoring the mass depletion of an item in a storage unit, the computer implemented method comprising: responsive to detecting, by a processor of a computer, an initial presence of an item in the storage unit, collecting data about the item, wherein the data include an item identification and a product type; and responsive to detecting, by the processor, the presence of the item resting on a portion of a plurality of mass sensors arranged in a grid of mass sensors of a first mass sensor shelf of the storage unit, collecting an initial mass of the item by adding up the total increase in mass measured by the portion of the grid of mass sensors on which the item is resting; searching, by the processor, a database for a recorded item containing the same item identification; retrieving, by the processor, a total mass of the recorded item from a database; comparing, by the processor, the initial mass of the item with the total mass of the recorded item; and responsive to a difference of less than a predetermined amount between the initial mass of the item and the total mass of the recorded item, setting, by the processor, a tare mass of the item equal to a tare mass of the recorded item retrieved from the database; responsive to detecting, by the processor, the item has been removed from the first mass sensor shelf and replaced in the storage unit on the first or a second mass sensor shelf, collecting a current mass of the item; and determining, by the processor, a mass depletion of the item as the current mass of the item minus the tare mass of the item; and responsive to the mass depletion of the item reaching a threshold depletion, alerting a user.