The method of equivalence applied to three state, two input control systems

The feedback equivalence of three-state two-input nonlinear control systems is analyzed by using Cartan´s method of equivalence. The control linear and linear equivalents are classified, including examples of control linear systems which are inequivalent to a linear system. The existence of time-critical closed-loop controls is demonstrated for `fully nonlinear´ control systems. The existence of natural contact structures and Riemannian structures is demonstrated for certain classes of systems