• For a regulated system the control output ’u’ can be estimated using the desired system state.

• The system state is often difficult to measure directly, so an estimator can be used. .

• A regulator can use an estimate of the system state to




• The estimators and regulators can be designed separately and then combined. This is the separation principle.

• The simplified block diagram for the system is,


• The compensator,


• This can be converted to a transfer function for the regulator.

• The system can also be set up for a compensator by assuming the setpoint input is not zero,


• Consider an example of a regulator/estimator design,





• This system can be implemented with a C program as shown below,



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