FIGURE 6.

An overview of the state machines defining the behaviour of the welder in the welding cell, highlighting the interactions between the process and safety layers. An excerpt of the safety controller state machine is included to highlight the control of the safety mode and welder activity. The transitions capture both the messages sent, and the guard enabling the transition. (A) Welder safety behaviour model. (B) Welder process behaviour model. (C) Except of the safely controller behaviour model, including abstract state core to highlight controller actions.