US 12,454,448 B2
Control method, control device, and control system for detecting abnormality in automatic forklift operation
Takumi Shigemasa, Toyota (JP); Daisuke Asami, Toyota (JP); Yoshiaki Sato, Toyota (JP); Yutaka Oshima, Miyoshi (JP); and Tatsuya Mita, Kariya (JP)
Assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP); SHINMEI INDUSTRY CO., LTD., Toyota (JP); and KABUSHIKI KAISHA TOYOTA JIDOSHOKKI, Kariya (JP)
Filed by TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota (JP); SHINMEI INDUSTRY CO., LTD., Aichi (JP); and KABUSHIKI KAISHA TOYOTA JIDOSHOKKI, Kariya (JP)
Filed on May 10, 2023, as Appl. No. 18/315,038.
Claims priority of application No. 2022-087886 (JP), filed on May 30, 2022.
Prior Publication US 2023/0382703 A1, Nov. 30, 2023
Int. Cl. B66F 9/075 (2006.01); B66F 9/06 (2006.01)
CPC B66F 9/0755 (2013.01) [B66F 9/063 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A control method for controlling a forklift to unload a transport pallet onto an unloading place, the forklift including a load sensor configured to detect load of an item placed on a fork, and a lift height sensor configured to detect a lift height of the fork, the control method comprising:
acquiring load information of the transport pallet placed on the fork and lift height range information, the lift height range information indicating a lift height range, the lift height range being a range of height in which the fork is estimated to be positioned when unloading onto the unloading place is successful, the lift height range being determined based at least on a height of the unloading place;
performing a lowering operation based on the acquired load information and the acquired lift height range information, the lowering operation being an operation of lowering the fork with the transport pallet from above the unloading place;
performing an operation of pulling out the fork when a load value detected by the load sensor is equal to or less than a predetermined value and a lift height value detected by the lift height sensor is within the lift height range; and
determining that an abnormality is present when one of a first condition and a second condition is satisfied during the lowering operation, wherein:
the first condition is a determination by a processor that the lift height value is equal to or less than a lower limit value of the lift height range,
the second condition is a determination by the processor that the load value is equal to or less than the predetermined value and the lift height value is equal to or larger than an upper limit value of the lift height range,
the lift height value is a numerical height value detected by the lift height sensor on the forklift, and the lift height range is a range of numerical values starting from the lower limit value to the upper limit value, which is retrieved from a database outside the forklift, and
the database stores a plurality of lift height ranges each having a different numerical range, and one of the lift height ranges is selected based on the unloading place and retrieved by the forklift to be used in abnormality determination.