The goal for the robot is to move in a way that the sensory value in a single given sector reaches a given value. Figure 7.12 illustrates the result of two typical movements. In example A, the goal was to make the sector in the back right (number 4 in figure 7.3, right) attain a low value (for example, 50 pixels). The robot moved backward in a rightward curve. In example B, the front sector should attain a low value. Thus, the robot moved from the middle of the circle straight toward the obstacles.
The two optimization methods gave similar results (table 7.3). In almost all trials, both optimization methods found a solution (96% to 99%). In 15% to 18% of the trials, the final sector value matched exactly the desired value, and in almost half of the trials, the final value was within one pixel of the desired value. In more than 80% of the trials, the final sector value was closer to the desired than to the initial value, and in more than 90% of trials, the final sector value was changed in the right direction (increasing or decreasing).
The almost equal performance of the Simulated Annealing and the Powell's method did not depend on choosing just one goal sector. No noticeable difference was also observed when two and three defined goal sectors were defined (data not shown).