Version 2.x of the Soccer Server provides some additional sensory input to the client. The client can always ignore the extra information and proceed as described above. However, it can use the additional sensory information to improve its memory model.

As sensory input, the client receives the relative angle of a boundary line. From this angle and the knowledge of which line, the global angle of the client can be computed and known exactly at any moment. This additional piece of information can be used to improve our model of the field. Using the same assumptions, we can now perform triangulation when only one marker is in view. Now the only case requiring estimation is when there are no markers in view.

When a marker is visible, the client's rotation and distance travelled can be calculated as follows. From the previous time step we know the relative position of the markers along with the distance and direction of the boundary line for the current and previous time step. Since we always can calculate global angle, the client's rotation is simple to compute, but distance travelled is more difficult. The diagram and associated calculation for distance is given below.

Wed Dec 17 13:44:25 EST 1997