Material Handler (MH) MPSG

The accessibility graph for the material handler is again a generic graph that is capable of handling both the automated and human material handlers. The pick_s and pick_ns messages are for an automated material handler (e.g. a robot arm) representing synchronous and non-synchronous pick tasks. Put message has the same structure for the automated material handler. In case of a human material handler, ordinary pick and put messages are provided, which are always non-synchronous. Although it seems like having double messaging for non-synchronous pick and put, the messages are separated for the purpose of creating a difference between the responses. Because in case of a non-synchronous activity, the part program for a robot handler can be written such that the robot will clear away automatically after it puts (picks) the part. However for a human material handler, the controller has to be sure that the operator is cleared from the put (pick) location, since there may be a hazardous situation coming along with the next step (e.g. a machining operation). Therefore, as seen in the graph, pick_ns message automatically sends a clear_ok while regular pick gets a clear_bh message from BIG-E.

MH Graph

M file