Direct Multivariable Model Reference Adaptive
Control
Adaptive algorithms have been developed for tuning control parameters
in the presence of system uncertainties and/or on line parameter
variations.
In explicit or indirect adaptive control, an identifier must be
implemented to
give estimates of these unknown parameters; these parameters are then
used for
control computation. In implicit or direct adaptive control,the control
gains
are computed without need for the intermediate identification procedure.
One
particular procedure that is especially attractive for multiple input
multiple
output systems is model reference adaptive control (MRAC). However in
order
to guarantee perfect tracking, certain positivity conditions need to be
satisfied. Because direct MRAC procedures are easily implementable,
various
procedures have been developed for alleviating the satisfaction of these
positivity conditions. Such procedures will be presented and illustrated
with examples that apply MRAC to drug infusion control, robotics, and
large structural systems.