On the equivalence between ADRC and Flat Filter based controllers: A frequency domain approach

An equivalence is established between Extended State Observer (ESO) based Active Disturbance Rejection Control (ADRC) and Flat Filter (FF) controllers in the context of perturbed pure integration systems. These are known to constitute a most convenient paradigm for the control of SISO flat nonlinear systems. It is shown that a Reduced Order ESO (ROESO) based ADRC strategy has a unique equivalent Flat Filter counterpart. The reverse statement is...