Multi-resolution path planning for marine surface vehicle considering environmental effects

For ship navigation, many researchers have adopted ideas from traditional robot navigation technology. In most cases, however, they haven´t considered sufficiently, or even ignored sometimes, hydrodynamic or aerodynamic effects in ocean environment when they perform path planning. This may result in waste of enormous energy or sometimes induce potential collision risk. We should consider much more about environmental effects than in path planning on land, since sometimes navigation in ocean environment is more likely to navigate the vehicle on the terrain where several different vector and scalar forces exist. The real-time control itself is essential indeed in navigation problem for unexpected collision avoidance, however, we can save the power and even reduce collision risks by considering environmental effects earlier, in path planning step, through reducing the error between a predetermined path from path planning and the actual position of a vehicle. Considering external loads in the path planning step is also more desirable rather than in the path following step because computational resource is limited in field operations in most cases. If the shallow water effect as well as tidal currents and winds for the surface ship navigation are considered, more economical and thus efficient path can be found. Incorporating this concept together, more realistic and practical route can be generated, and ship domain for collision avoidance also can be reduced reasonably. The proposed path planning considering environmental effects was examined through computer simulations for validation.