Mumbai University > Electronics Engineering > Sem 4 > Linear Control Systems

Topic: Compensators and Controllers

Difficulty : Low

Marks : 5M

1) First the model of the process is linearized around a certain nominal point and the controller is designed on the basis of that linearized model and finally implemented on the process.

2) Hence, the controller is applicable for certain domain around the nominal operating point around which the model has been linearized.

3) However, if the process deviates from the nominal point of operation, the controller will lose its efficiency.

4) In such cases, the parameter of the controller needs to be re-tuned in order to retain the efficiency of the controller.

5) When such retuning of the controller is done through some "automobile updating scheme" the controller is termed as adaptive controller.

6) This Technique is as shown in figure.

Approaches for designing adaptive controllers.

OR

Example of adaptive controller.

1) Model Reference Adaptive Control method (MRAC)

2) Gain scheduling

3) Self tuning method

1) Model Reference Adaptive Control method (MRAC)

i) The following figure shows the schematic of a Model Reference Adaptive Control method (MRAC)

ii) It contains two loops. The inner loop contains the regular feedback mechanism whereas the outer loop contains an ideal reference model which the process needs to follow.

iii) The process and model outputs are compared and the error function is minimized through a suitable optimization routine in order to arrive at the re-tuned controller parameters.