Component Sequencing Methodology

In order to detail the component sequencing methodology, a sequence of decision trees based on the previous taxonomy was developed. The approach was taken since of the forward chaining nature of the PCB assembly planning process. In such an environment, a knowledge search generally proceeds in a stepwise fashion through a knowledge base along with a new branch to be decided at each step. A decision tree is a grouping of questions that are related to a list of fact and follow a exact consulting path.

The path may take several possibilities and explore several directions for those facts, providing different results, but while the end of a path is reached, the methodology would have come to a decision about these facts and, such as, reached a goal. Given diagram depicts the resistor decision tree as developed for the CBA system.

The previous decision trees can be utilized to derive some of the decision rules of the methodology's knowledge base. It can be done by tracing all paths leading to each terminal node of each single decision tree. A terminal node is one presented by a square box and does not have any branches leaving. For illustration in diagram the node marked number 7, "resister is stand-up component," is a terminal node. The path leading to such node via the nodes 1, node 3, and node 5 A decision tree-making rules can then be written for arriving to this node as given:

IF            (the CTC is not called out) AND

(The resister is not a resister network) AND (the resistor is not a variable resistor)

THEN (the resistor is a stand-up component) AND (insert first)