PHOTODETECTOR SYSTEM FOR DETECTING OBSTACLES IN AISLES BETWEEN MOBILE SHELVING CARRIAGES

摘要

Obstacles are protected against collision in aisles adjacent mobile storage units with an IR transmitter mounted in spaced apart relation to an IR receiver on a unit. For initializing and calibrating the system a microcomputer controls the transmitter to emit IR pulses of increasing width at a uniform repetition rate. If there is no defect in the system the receiver responds with output electric pulses after the IR pulse width is reached that has the minimum integrated energy to exceed the input signal threshold of the receiver. The minimum energy pulse width is stored in the microcomputer and the system switches to a run mode allowing storage units to move when commanded. The computer responds to the absence of returned pulses from the receiver by inhibiting the system so the mobile unit will not run. If returned pulses are not in the proper phase relationship the system goes into a diagnostic mode wherein the interval between transmitted IR pulses is reduced in increments for reasons including determining if there may only be temporary ambient IR interference. If the problem does not clear up by the time the interval is reduced to one-half normal interval the system locks out.