Optimal Control, Introduction.
Sometimes it is desirable to choose control parameters or inputs which optimises
some parameter associated with the system. Here P, PD and PI control and modified inputs are examined subject to minimisation of the quadratic performance index J
given by the following equation where e is the error and m is a weighting parameter:-
More general expressions involve the state and input vectors. Application of the general case can be laborious, even this simple
version may have complex behaviour.
The error determines the
output from a proportional controller while the derivative of the
error determines the output from a derivative controller.
Because of the numerical approximations used here for J, the numerical
values obtained for J are approximate, accuracy increases with decreasing hgain.
When enabled some of the applets are illustrated below:-
Return to main page
Return to page index
COPYRIGHT © 2006 Cuthbert Nyack.