Tracking
Control for Nonlinear Systems with State and Control Constraints:
A Nee
Reference Governor Approach
Department of Aerospace
Engineering
University of Michigan
Using various methodologies such as linear-system
design techniques and gain scheduling, it is often possible to implement
feedback controllers that provide accurate tracking performance over a wide
range of operating conditions.
However, rapid transitions in reference commands often cause violation
of crucial constraints on state and control variables. In this talk I present a reference
governor approach for avoiding such violations when there are significant
nonlinearities in the descriptions of the closed-loop system and constraints.
A reference governor is a nonlinear precompensator
that modifies the time evolution of reference commands in a
constraint-admissible way. The
approach described here differs from others in how potential constraint
violation is anticipated. There is
no need to characterize certain, difficult-to-determine positively invariant
sets. This significantly broadens
the class of methods available for finding a suitable function V, the main computational element needed in the
implementation of the reference governor.
It also permits the treatment of certain types of uncertainties.
Theory of the new approach is reviewed, including the
statement of very basic conditions that assure that the reference governor has
nice properties such as finite settling time. Several specific methods for obtaining V are discussed.
One promising approach is the use off-line system simulation and machine
learning. An example application
is described.
3:30 - 5:00 p.m.
1500 EECS