With this brief, the authors present algorithms for model-free
stabilization of unstable dynamic systems. An extremum-seeking algorithm
assigns the role of a cost function to the dynamic system's control
Lyapunov function (clf) aiming at its minimization. The minimization of
the clf drives the clf to zero and achieves asymptotic stabilization.
This approach does not rely on, or require knowledge of, the system
model. Instead, it employs periodic perturbation signals, along with the
clf. The same effect is achieved as by using clf-based feedback laws
that profit from modeling knowledge, but in a time-average sense. Rather
than use integrals of the systems vector field, we employ
Lie-bracket-based (i.e., derivative-based) averaging.
The brief contains numerous examples and applications, including
examples with unknown control directions and experiments with charged
particle accelerators. It is intended for theoretical control engineers
and mathematicians, and practitioners working in various industrial
areas and in robotics.