For open control system which of the following statements is incorrect?

For open control system which of the following statements is incorrect?

Right Answer is:

Recalibration is not required for maintaining the required quality of the output


Open-loop control system

  • In any open-loop control system, the output is not compared with the reference input.
  • Thus, to each reference input, there corresponds a fixed operating condition, as a result, the accuracy of the system depends on the calibration.
  • In open-loop system control action is independent of the output.
  • In the presence of disturbances, an open-loop control system will not perform the desired task because when the output changes due to disturbances, it is not followed by changes in input to correct the output.

Disadvantage of Open-loop system

In an open-loop, if the systems undergo rapid changes in either the external variables or in their own behavior. In such situations, open-loop control will not be satisfactory, since it would often require recalibration and adjustments of the calibration setting.

The main disadvantages are the following:

  1. Disturbances, internal or external, cause drifts in the desired output.
  2. Changes in calibration cause errors in the system.
  3. Re-calibration of the system may be necessary from time to time in order to maintain the required quality of output.

There are several limitations of open-loop systems which include: slow system response, poor disturbance rejection, poor tracking under uncertainties, high sensitivity to system parameter errors (e.g., errors in plant or controller gains), and high sensitivity to changes in calibration errors (hence recalibration is usually necessary).

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