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## 5.4 Recognizing the Right Decision - Left, Right, Fork

There are four main concepts involved in making a decision - command definition, priority ordering, memory heuristic, thresholding.

### 5.4.1 Command Definition

Originally, we defined "left" and "right" to have many constraints in terms of area and bordering, but the execution of these commands had a small degree of success. The turning error of the tank, angle of web cam, and range of web cam vision encouraged re-engineering.

For definitions of left and right, we simplified our previous algorithm and received a 100% correct decision rate. To decide "left," our only constraint is that there must be area in the left-third region, greater than a minimal threshold. The same goes for "right." A smarter algorithm for "left" would have been if the excess of [left-third area - right-third area] was greater than a minimal threshold, decide "left." Unfortunately, even that constraint caused problems in decision making.

 Figure : Ideal Case: Decide left?
 Figure : Ideal Case: Decide right?
With fork being a more complicated command, we imposed many more constraints. However, we only needed to use border analysis to recognize a fork. Area was an interesting idea, one we started with initially, but the problem was that the Sentinel would reach a fork from different angles each time. This made it difficult to choose specific regions of area. Below are examples to ponder the claim. Consider using a plausible method of analysis - if there's area in the top left corner, top right corner, and bottom center, then "fork."

 Figure : Ideal Case: Decide to fork?
 Figure : Off to the Left: Decide to fork?
 Figure : Working Case:
 Figure : Off to the Right:
Not all forks were caught based on the area method. The border method is illustrated by the image below. It is easier to see in the picture than it is to use words. Basically, fork is composed of a logic statement of these borders:

 (left top + left left top + left middle) AND (right top + right right top + right middle) AND [ (left bottom + center bottom + ~right bottom) OR (~left bottom + center bottom + right bottom)

 Figure 1.11: Border Method