Material Transporter / Handler (MT/MH) MPSG
MTMH is a combination of two different classes of classical shop floor controllers: material transporter (MT) and material handler (MH). This controller is basically intended to serve as an administrator for a human material-handling operator in the shop floor. It combines the transportation messages with the handling messages. This controller can be used for an automatic material transporter/handler (e.g. an AGV carrying a robot arm) by including a few messages for synchronous operations (i.e. automatic clamping).
M file
The part is first assigned to MT/MH and then the MT/MH can first move to the location where it will pick up the part (in case it is not already at that location). If the MT/MH is already at the desired location it can directly pick up the part and proceed to state 9. At this state, it can either move to another location or it can put the part right at the same location. The latter one is for reprocess and refixturing of the part in the same machine. After the part is put to the desired location, the MT/MH is given a clear message to clear away from the machine or buffer. This is done for safety purposes, because after a put the machine will be ready to start processing the part. In the manufacturing system, the clear command verified when the door of the machine is closed. Namely, clear_ok message is sent to BIG-E after the machine door is closed. The signal required for this purpose is provided by a couple of limit switches attaché to the machine hood mating the door area. After the MT/MH has cleared from the machine or buffer, the part is unassigned and MT/MH becomes available for another part.
One inherent assumption of this controller is MT/MH can only possess one part at a time. This assumption is valid for a human operator, however can be improved for an automatic material transporter/handler having a buffer space.
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