**2.1.1 Guidance**

The guidance system is responsible for producing the desired trajectory for the vehicle to follow. This task is completed by taking the desired waypoints defined pre-mission and, with the possible inclusion of external environmental disturbances, generates a path for the vehicle to follow in order to reach each successive waypoint (Fossen, 1994, 2002). Information regarding the current condition of the vehicle, such as actuator configuration and possible failures, can also be utilised to provide a realistic trajectory for the vehicle to follow. This trajectory then forms the desired state of the vehicle, as it contains the desired position, orientation, velocity, and acceleration information.
