Patent attributes
A stacker crane includes a transporter, a slide fork, first to third sensors, a counter, and a main controller. The transporter moves from a shelf on which an article is supported to an empty shelf. The slide fork is mounted on the lift stage and transfers the article to and from the shelf. The first, second and third sensors recognize an abnormality of the article moved by the movement of the transporter. The counter counts the number of event occurrences. When an abnormality is recognized by the sensor, the main controller reduces a moving speed of the transporter, and when no abnormality is recognized by the sensor upon reduction in the moving speed, the movement of the transporter is continued. When the number of event occurrences reaches a first threshold, the stacker crane is brought into an abnormal-stop state.
