Article transport facility

An article transport facility, comprising:

• a plurality of transport vehicles configured to transport articles;
• a first traveling rail for the plurality of transport vehicles to travel;
• a second traveling rail below the first traveling rail, wherein the second traveling rail is a rail for the plurality of transport vehicles to travel;
• a lifter configured to lift and lower the plurality of transport vehicles between the first traveling rail and the second traveling rail;
• and
• a control system configured to control the plurality of transport vehicles and the lifter, and
• wherein:
• the first traveling rail comprises a first upstream area and a first downstream area discontinuous from each other, the first upstream area is upstream from a lift area in which the lifter is located, and the first downstream area is downstream from the lift area,
• the second traveling rail comprises a second upstream area and a second downstream area discontinuous from each other, the second upstream area is upstream from the lift area, and the second downstream area is downstream from the lift area,
• the lifter comprises a lift rail for the plurality of transport vehicles to travel, and the lift rail ascends and descends in the lift area,
• the lift rail at a first position connects the first upstream area and the first downstream area in the first traveling rail, and the lift rail at a second position connects the second upstream area and the second downstream area in the second traveling rail,
• the plurality of transport vehicles in an entry request section transmit an entry request signal to the control system to request permission for entering the lift rail, the plurality of transport vehicles in a preliminary request section transmit a preliminary request signal to the control system, the entry request section is defined in each of the first upstream area and the second upstream area, and the preliminary request section is defined upstream from the entry request section in each of the first upstream area and the second upstream area,
• the plurality of transport vehicles comprise a target transport vehicle and a non-target transport vehicle other than the target transport vehicle,
• in response to the entry request signal from the target transport vehicle, the control system transmits an entry permission signal to the target transport vehicle to permit entry into the lift rail when the lift rail is at a target position and no non-target transport vehicle is on the lift rail, where the target position is one of the first position or the second position corresponding to a target upstream area, the other of the first position or the second position not being the target position is a non-target position, and the target upstream area is one of the first upstream area or the second upstream area comprising the target transport vehicle, and
• in response to the preliminary request signal from the target transport vehicle, the control system performs a preliminary lifting process of moving the lift rail not at the target position to the target position when no non-target transport vehicle is on the lift rail and no entry request signal is received from the non-target transport vehicle.