  The motivation behind mathematically modeling the human operator is to help
explain the response characteristics of the complex dynamical system including
the human manual controller. In this paper, we present two approaches to human
operator modeling: classical linear control approach and modern nonlinear
control approach. The latter one is formalized using both fixed and adaptive
Lie-Derivative based controllers.
  Keywords: Human operator, linear control, nonlinear control, Lie derivative
operator
