Publisher Summary The purpose of a control system is to compare the plan to reality and issue commands to the servos or other output devices to make reality follow the plan. A closed loop system is one that measures the error between the rabbit and hound and attempts to minimize the gap without becoming erratic. The classical control theory has been in existence for a very long time. Engineering courses have traditionally taught mathematical techniques involving poles and zeros and very abstract mathematics that beautifully describe the conditions under which a control can be designed with optimal performance. Normally, this involves producing a control system that maintains the fastest possible response to changing input functions without becoming underdamped. Notwithstanding the wondrous advances in computer aided design systems (CAD), dynamically modeling such highly complex systems reliably is often impractical because of the many variables and unknowns. For this reason, when most engineers are confronted with such a task, they seek to find simpler techniques.