Patent attributes
Interposer assemblies may be inserted between a traditional shelf and traditional supports for the shelf. Each of the interposer assemblies may be configured to generate signals corresponding to changes in loading on the traditional shelf, and information regarding the changes may be determined to identify items placed onto or removed from the traditional shelf, and locations at which the items were placed or from which the items were removed. The interposer assemblies may include one or more load cells, such as strain-gage load cells, and analog signals generated by the load cells may be processed to determine a mass of an item placed on the shelf or removed therefrom. The item, and a location corresponding to the item, may be determined based on the mass and according to standard equilibrium procedures.