Generation of restart states for manufacturing cell controllers

Calculating restart states using reset transitions

“…With such an open approach, different postprocessing can be applied on the result to meet different needs. For instance, in [3] the set of valid restart states are minimized with the constraint that all potential error states have at least one valid restart state. For other systems it can be desirable to select one valid restart state for each potential error state, such that the operator action to place the physical system in a corresponding physical state becomes as simple as possible, according to some appropriate metric.…”

“…The method is a generalization of the work presented in [3] and [6]. Supervisory control theory [11] is used to calculate restart states in the control system, that is, states from where it is valid to restart the system after an error such that the requirements on the nominal and the restarted productions are fulfilled.…”

“…Error recovery in manufacturing systems is, however, a complicated task [3], often divided into three major activities [4]: detection of discrepancies between the intended behavior of the control system and the actual behavior of the physical system, diagnosis to find the original fault causing the observed error leading to an unsynchronization between the control and the physical systems, and recovery of the systems to continue the production. Recovery is further partitioned into error correction to remove underlying faults and restart to resynchronize the control system and the physical system such that the production can be resumed [5].…”

Planning in assembly systems — A common modeling for products and resources

“…Additional transitions, or sequences of locations and transitions, can also be added to represent restart of the system after a failure. These transitions are not generic and may not be applied to all operations; they can be automatically computed and added to the initial model [2].…”

Fault Handling in PLC-Based Industry 4.0 Automated Production Systems as a Basis for Restart and Self-Configuration and Its Evaluation

“…[20]. Andersson et al [21] [22] address the challenge to automatically derive operation sequences for restarting manufacturing systems (and here especially assembly cells typically used in the automotive industry). In context of these works, restarting is the procedure to "resynchronize the control system and the physical system, such that the production can be restarted and eventually complete" [23].…”