B1 – 14 Closed-loop control
1.5.1 Description of the dynamic response of a controlled system In the examples shown in Fig. B1-7 and Fig. B1-8, the time response was shown assuming a sudden change in input variable. This is a commonly used method of establishing the time response of system.
Step response The response of a system to a sudden change of the input variable is called the step response. Every system can be characterized by its step response. The step response also allows a system to be described with mathematical formulas.
Dynamic response This description of a system is also known as dynamic response. Fig. B1-9 demonstrates this. Here the manipulated variable y is suddenly increased (see left diagram). The step response of the controlled variable x is a settling process with transient overshoot.
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Manipulated variable y
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Controlled system
Controlled variable x
Fig. B1-9: Step response
Process Control System • Festo Didactic