Mechanism and utilization of Optical data transmission device for AGV (automated guided vehicle) / AMR (transport robot)

As there is a demand for efficiency and automation in factories and logistics, AGVs (Automated Guided Vehicles) and AMRs (Transportation Robots) is being actively promoted.
This time we explain the optical data transmission device that is often used for exchanging control signals when transferring cargo with AGV and AMR.

Optical data transmission device uses light as a medium. It does not require cables between devices, so it can be installed in the locations where it is difficult to lay cables and can be used for exchanging data with moving objects such as unmanned guided vehicles, stacker cranes in multi-level automated warehouses and overhead traveling cranes.

Parallel type optical data transmission device transmits input/output data of ON/OFF signals in bit.
There is also serial type that can be alternative to communication cables such as RS232C, RS422, and Ethernet.
This time, we explain the parallel type that is often used in AGV/AMR.

Optical data transmission device receives the input (IN) from the device and communicates and turns on the output (OUT) of the other side of optical data transmission device. Two-way transmission and reception is possible because a transmission and reception are housed together.
When the switch A is turned on or off, a optical signal is sent to B to turn the switch B on or off.
The transmission capacity of 4 bits or 8 bits indicates the number of switches 4 or 8.

As a method of use in AGV/AMR, various instruction signals are exchanged with the station (ground side device) without cables using optical data transmission device during transfer.

As an example of the transfer system of semiconductor manufacturing equipment, the cart that arrives at the load port specifies the load port number to be transferred using 2 bits.

The trolley side turns on a signal indicating that communication is valid, and the load port side turns on a request signal when transfer preparations are complete. The truck side turns on the request signal to the load port side to start the transfer operation, and the load port side turns on the request acceptance signal. The trolley confirms that the acceptance signal has been turned on, turns on the signal indicating that the transfer is in progress, and starts the transfer.
When the load port side completes the transfer, it turns off the request signal to the trolley side, and the trolley side turns off the transfer signal. The truck side turns off the request signal and turns on the completion signal.

The load port turns off the request acceptance signal after confirming that the completion signal on the truck side has turned on. Also, after confirming that the request acceptance signal has been turned off, the truck side turns off the completion signal, communication enable signal, and load port selection signal.

*For details, please check the SEMI Standard SEMI E84 from the SEMI Industry Association.

In this way, we will transfer while exchanging signals called handshake.

Parallel type has a line-up with transmission capacities from 4 bits to 16 bits.