Basics

A control system is several components connected together to achieve a goal. There are two basic types of systems...

• Open Loop: an input is fed into a system and through the process of the system and a direct output is achieved.
• Closed Loop: uses a feedback loop to compare the actual output with the desired output and makes adjustments to the input to achieve the desired output.

The process of the control system is an input is fed to a controller then to a actuator then to the plant from the plant a sensor could be used (in a closed loop) to provide feedback to the controller. This is a picture of the layout with feedback...









The Process of a control system consists of:

• Controller: something that monitors and affects the operation process. Example: driver in a car, computer, position of a screw in a pressure regulator.
  
• Actuator: device for moving or controlling a mechanism. Example: Steering mechanism, engine, valve.
  
• Plant: Example: car, drive train, flow of a fluid.
  
• Sensor: Device that feeds the output back to the controller, where the controller can make adjustments to achieve the desired result. Example: eyes(driving), speedometer, valve area.

Control engineering is interested in goal-oriented systems; systems that have characteristics of self-organizing, learning, and that can adapt. Many control systems consist of electrical, mechanical, and computer components although not limited to just these.


Examples of control systems: computer, driving a car, refrigerator, thermostat, oven, furnace, speed/pressure controls, robots, etc..


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