What are the operational objectives that a control system is called to achieve?

The answer to this question determines the so-called control objectives. They may have to do with:

- Ensuring the stability of the process, or

- suppressing the influence of external disturbances, or

- optimizing the economic performance of a plant, or

' - combination of the above.

At the beginning the control objectives are 'defined qualitatively and subsequently they are quantifi'ed,

usually in terms of the output variables.