Control system facts for kids

Control system logic diagram

Control system is a device or system that gives commands to manage the behavior of other devices or systems. The commands can be set or programmed, and the output is determined by the input. A control system is represented by a logic diagram. A control system is a device or set of devices to manage, command, direct or regulate the behavior of other devices or systems.

There are two common classes of control systems, with many variations and combinations: logic or sequential controls, and feedback or linear controls. There is also fuzzy logic, which attempts to combine some of the design simplicity of logic with the utility of linear control. Some devices or systems are inherently not controllable.

The term control system may be applied to the essentially manual controls that allow an operator to, for example, close and open a hydraulic press, where the logic requires that it cannot be moved unless safety guards are in place.

An automatic sequential control system may trigger a series of mechanical actuators in the correct sequence to perform a task. For example various electric and pneumatic transducers may fold and glue a cardboard box, fill it with product and then seal it in an automatic packaging machine.

In the case of linear feedback systems, a control loop, including sensors, control algorithms and actuators, is arranged in such a fashion as to try to regulate a variable at a setpoint or reference value. An example of this may increase the fuel supply to a furnace when a measured temperature drops. PID controllers are common and effective in cases such as this . Control systems that include some sensing of the results they are trying to achieve are making use of feedback and so can, to some extent, adapt to varying circumstances. Open-loop control systems do not directly make use of feedback, but run only in pre-arranged ways.

Classes

• Open loop control system-without feedback
• Closed loop control system-with feedback

Images for kids

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  The centrifugal governor is an early proportional control mechanism.

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  Example of a single industrial control loop; showing continuously modulated control of process flow.

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  Effects of varying PID parameters (Kp,Ki,Kd) on the step response of a system.

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  Change of response of a second-order system to a step input for varying Ki values.

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  A DCS control room where large screens display plant information. The operators can view and control any part of the process from their computer screens, whilst retaining a plant overview on the larger screens.

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  A control panel of a hydraulic heat press machine

See also

In Spanish: Sistema de control para niños