Specifications for Closedloop Response

2 PERFORMANCE OF FEEDBACK CONTROLLERS 7.2.1 Specifications for Closedloop Response 

There are a number of criteria by which the desired performance of a closedloop system can be spedlied in the time domain. For example, we could specify that the closedloop system be critically damped so that there is no overshoot or oscillation. We must then select the type of controller and set its tuning constants so that it will give, when coupled with the process, the desired closedloop response. Naturally the control specification must be physically attainable. We cannot make a Boeing 747 jumbo jet airplane behave like an F-IS fighter. We cannot 

There are a number of time-domain specifications. A few of the most frequently used dynamic specifications are listed below (see also Prob. 6.11). The traditional test input signal is a step change in setpoint. 

Overshoot the magnitude by which the controlled variable swings past the setpoint 

Rise time (speed of response) the time it lakes the process to come up to the new setpoint 

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