ABSTRACT
When confronted with a control problem for a complicated physical process, the control engineer usually follows a predetermined design procedure, which begins with the need for understanding the process and the primary control objectives. A good example of such a process is that of an automobile “cruise control,” designed with the objective of providing the automobile with the capability of regulating its own speed at a driver-specified set-point (e.g., 55mph). One solution to the automotive cruise control problem involves adding an electronic controller that can sense the speed of the vehicle via the speedometer and actuate the throttle position so as to regulate the vehicle speed at the driver-specified value even if there are road grade changes, head-winds, or variations in the number of passengers in the automobile. Control engineers typically solve the cruise control problem by (1) developing a model of the automobile dynamics (which may model vehicle and power train dynamics, road grade variations, etc.), (2) using the mathematical model to design a controller (e.g., via a linear model develop a linear controller with techniques from classical control), (3) using the mathematical model of the closed-loop system and mathematical or simulation-based analysis to study its performance (possibly leading to redesign), and (4) implementing the controller via, for example, a microprocessor, and evaluating the performance of the closed-loop system (again possibly leading to redesign).
