Abstract
The objective of this work is to present a comparative study between two rotor resistance estimators for a nonlinear model of a shunt DC motor. The first one is based on the recursive least square algorithm where the second one is synthesized around the direct Lyapunov theory. The rapidity of convergence and dynamic precision of these parameter estimators are studied and compared when an unforeseeable rotor resistance default affects the model of the studied system. The validity and the robustness of both proposed estimators will be demonstrated via a simulation study. A performance synthesis of the studied estimators will be performed to determine the advantages and disadvantages of both estimators. This will lead to proceed to a future design and implementation of an online guaranteed stability default detection mechanism.