A controller-implemented method for managing inventory of pallets on a pallet rack is provided. The controller-implemented method may include engaging a plurality of exciters to generate a rack frequency in the pallet rack, receiving the rack frequency at a plurality of corresponding harvesters, detecting variations between the rack frequency generated by the exciters and the rack frequency received by the harvesters, and detecting one or more load characteristics of pallets on the pallet rack based on the variations.