Examples of Modern Control Systems

Control engineering is concerned with the analysis and design of goal - oriented systems. Modern control theory is concerned with systems with self - organizing, adaptive, robust, learning, and optimum qualities.

The control of an industrial process (manufacturing, production, and so on) by automatic rather than human means is often called automation. The concept of automation is central to our industrial society. In its modern usage, automation can be defined as a technology that uses programmed commands to operate a given process, combined with feedback of information to determine that the commands have been properly executed. Automation is often used for processes that were previously operated by humans. When automated, the process can operate without human assistance or interference. In fact, most automated systems are capable of performing their functions with greater accuracy and precision, and in less time, than humans are able to do. Automation is prevalent in the chemical, electric power, paper, automobile, and steel industries, among others. With the demand for flexible, custom production emerging in the 1980s, a need for flexible automation and robots is growing. A robot is a computer controlled machine and is a technology closely associated with automation.

There has been considerable discussion concerning the gap between practice and theory in control engineering. However, it is natural that theory precedes the applications in many fields of control engineering. It is interesting to note that in the electric power industry the gap is relatively insignificant. The electric power industry is primarily interested in energy convertion, control, and distribution. It is critical that computer control be increasingly applied to the power industry in order to improve the efficiency of using energy resources. Also, the control power plants for minimum waste emission has become increasingly important. The modern, large-capacity plants require automatic control systems that account for the interrelationship of the process variables and the optimum power production. The electric power industry has utilized the modern aspects of control engineering for significant and interesting applications.

Another important industry, the metallurgical industry, has had considerable success in automatically controlling its processes.

Rapidly rising energy costs are resulting in new efforts for efficient automatic energy management. Often computer controls are used to control energy use in industry and stabilize and connect loads evenly to gain fuel economy. The other field of using modern control theory is aeronautics and space applications.

Automatic control of agricultural systems is meeting increased interest. Also, there are many applications of control system theory to biomedical experimentation, diagnosis, and biological control systems.

Another very important application of control technology is in the control of the modern automobile. Control systems for suspension, steering, and engine control are being introduced. Other familiar examples of control systems in the home are oven, furnace and water heater. In industry, there are speed controls, process temperature and pressure controls, position, thickness, composition, and quality controls among many others.

So feedback control systems are used extensively in industrial applications. The potential future application of feedback control systems and model appears to be unlimited. It appears that the theory and practice of modern control systems have a bright and important future and certainly justify the study of modern automatic control system theory and application.

Terms and Concepts

Closed-loop feedback control system.A system that uses a measurement of the output and compares it with the desired output.

Control system.An interconnection of components forming a system configuration that provides a desired response.

Feedback signal.A measure of the output of the system used for feedback to control the system.

Multivariable control system.A system with more than one input variable and more than one output variable.

Negative feedback. The output signal is fedback so that it subtracts from the input signal.

Open-loop control system. A system that utilizes a device to control the process without using the feedback. Thus the output has no effect upon the signal to the process.

Positive feedback. The output signal is fedback so that it adds to the input signal.

Process. The device, plant or system under control.

System. An interconnection of elements and devices for a desired purpose.