A TRIANGULAR FORM FOR FLAT NONLINEAR SYSTEMS WITH TWO CONTROLS AND FIVE OR LESS STATES

This paper shows that, for flat affine time-invariant continuous-time nonlinear systems with two controls and five or less state variables, there exists a smooth change of coordinates and a time-invariant regular static state feedback such that the system is described by a triangular form. The presentation is based on an infinite-dimensional differential geometric approach to nonlinear control systems.