System for counting persons in a high density mobile storage system
 High density mobile storage comprising a mobile carriage between two stationary end shelving structures. Photoelectric light beam emitters and receivers are installed in the stationary structures. The light beams emitted pass through a passage in the mobile carriage and through the aisles between the mobile carriage and stationary structures. The passage in the mobile carriage is shielded to prevent interference with the light beams. The photoelectric emitters and receivers cooperate with a control to prevent rolling of the mobile carriage in response to sensing the presence of a person in any aisle, and to enable rolling of the mobile carriage in response to sensing the absence of persons in all aisles. The light beams are located to produce reliable sensing of persons entering and leaving the aisles. 
Tab Products Company
G A
G01V A47B
inventional inventional
David R. Jeffrey W.
Eaton Frank