Apparatus and method for detecting stock-out of articles on rack and rack

An apparatus for detecting stock-out of articles on a rack, the rack comprising a first end and a second end opposite to each other and being capable of accommodating the articles arranged from the first end towards the second end, the apparatus comprising:

• a distance detector, configured to detect a distance between an article farthest from the first end and one of the first end and the second end;
• and
• a controlling and processing unit, communicatively connected to the distance detector and configured to determine whether the articles are out of stock based on the distance;
• wherein the distance detector comprises:
• an elastic tape having a fixing end fixed to the first end and a winding end being retractable such that the elastic tape may extend and retract in the direction from the first end to the second end, wherein the material of the elastic tape comprises resistive material;
• a housing, configured to accommodate the winding end of the elastic tape and being capable of moving with the winding end as the elastic tape extends and retracts, wherein the housing has an opening through which the elastic tape passes to be wound up in the housing;
• and
• two electrode sheets, one of which being configured to be electrically connected to the fixing end of the elastic tape and the other being configured to be electrically connected to a portion of the elastic tape at the opening of the housing, the two electrode sheets being configured to measure resistance between the fixing end of the elastic tape and the portion of the elastic tape at the opening of the housing;
• wherein the controlling and processing unit is further configured to calculate the distance between the article farthest from the first end and the first end based on the resistance.