In order to find lakes when the camera can’t find any the marslander should move around mars, this is called roaming. It basically drives around and makes decisions based on light sensor readings. This can be seen in figure above. Using a fixed treshold for avoiding edges and lakes, like we did in the line tracking competition, does not suffice for the mars landscape. The sensor readings are different all around mars, due to the changing lighting and surface.
In order to still effectively use the light sensors a history of adjustable (limited) length is stored with readings of the landscape. This history is averaged out and new readings are compared with the average. Then if the values are significantly different for a number of consecutive times an edge or a lake is detected. This allows for the marslander to cope with the changing conditions.
Once an edge is detected the marslander will drive back a bit, then drive forward whilst steering in a appropriate direction (i.e. decided on which sensor is ‘triggered’). Then after a while it steers straight and continues to drive until a new edge is detected. This way is it ‘roams’ mars. A slightly exaggerated version is shown in the above figure and below a video is shown of our marslander just roaming around mars in this manner:
Tags: Mars Mission, Roaming, Video
