The high-level structure diagram in the picture below shows how the three system layers are connected to each other and the devices they interface. The diagram is simplified and only shows the main system structure. Level 1 takes care of monitoring the system and, if the main navigation system for some reason cannot control the USVs rudder, fallback autopilot. In level 2, navigation and collision avoidance are implemented. Level 3 is intended for scientific use and does not hold functions that are important for navigation, collision avoidance or system monitoring.