Active disturbance rejection control of singular differentially flat systems

A possible limitation of differentially flat systems stems from the possibility of gain singularities on open or closed regions of the flat output phase space. The evasion of control gain singularity poses an important theoretical problem even under the scope of Active Disturbance Rejection Control. In this article, we illustrate an interesting example of controlling a singular flat system, the inertia wheel pendulum, using the combined benefits of ADR control and flatness as applied to a carefully chosen flat tangent linearization model of the singular system.