Automatic Implementation and Verification of Coordinating PLC-Code for Robot Cells

Abstract A method for automatically generating the coordinating PLC-code for a multi-robot cell is presented. Finite state automaton models of the allocation and release of the spatial volumes that the robots share, as well as the sequences of each robot's allocations, are automatically extracted from a 3D simulation environment. This includes explicitly calculating the intersection between the robots' work envelopes, the spatial volumes where collisions may occur. The system model is then analyzed using the Ramadge-Wonham supervisory control theory to verify collision freeness and nonblocking. If necessary, a maximally permissive supervisor that guarantees these properties can be synthesized. The supervisor will include the necessary interlocks but in doing so still permits the robots as much freedom as possible. Thus, if one robot is delayed, the other robots may be free to book and enter a spatial volume that they normally would have to wait for. Finally, from the synthesized supervisor, PLC-code to be run in a controller for coordination of the robots is generated.