Question L5-C3

The question is about the choice of a navigation algorithm for global path planning of a robotic ship that navigates around the UK. On the right there is an illustration of the map of UK built by large sectors with regular points on the border. There are a start and an end point. The question is: "You have to design the navigation algorithm for a robotic ship that navigates around the UK, outside the territorial waters (22km from the coast), based on the vector map on the right. Which of the statements below are correct (multiple correct answers possible)?". Four possible statements are proposed. The student has to state, for each statement, if it is correct or wrong:

Statement A. is "Potential field navigation would not work here, as there are possible local minima.". This statement is correct, as the start and end points are on opposite sides of UK and the shape of UK introduced several local minima where a potential field approach would not find a path.
In the explanation of the student we would like to see that they understand that potential field can get trapped by the shapes of the UK island combined with the position of start and end.

Statement B. is "Voronoi diagrams need the information of the limits of the sea, not available in this map.". This statement is correct, as Voronoi diagrams require objects on both sides to find a middle path.
In the explanation of the student we would like to see that they understand that, by their definition, Voronoi diagrams require objects on both sides.

Statement C. is "Visibility graphs applied to the borders extended by 22km could generate optimal paths." This statement is correct, this is a common approach and all elements are there to work, and generate optimal paths.
In the explanation of the student we would like to see that they understand that a visibility graph, with the given implementation details, could solve the issue.

Statement D. is "An occupancy-grid map with cells of 10km of side and a A* path search could work, but the path would not be optimal." This statement is correct, as all elements of the statement are correct, in particular the fact that this will work and be sub-optimal because of the granularity of the grid.
In the explanation of the student we would like to see that they understand that this will work and not be optimal because of the granularity of the grid.

