| 摘要 |
First and second mobile carriers are accessible to individual cells defined in a storage. The first and second mobile carriers move along overlapped paths. First and second controller circuits are connected to the first and second mobile carriers, respectively. The second controller circuit is also connected to the first mobile carrier. Even when a defect occurs in the first controller circuit, the transport mechanism allows the second controller circuit to take over the control on the first mobile carrier from the first controller circuit. The control on the first mobile carrier serves to avoid interference between the first mobile carrier and any obstacle on the path. If the first mobile carrier is removed from the path of the second mobile carrier, the second mobile carrier is allowed to keep operating. The operation of the transport mechanism can be kept without any interruption.
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