In this paper, a new robust control method and stability analysis method using the higher order derivatives (HODs) of universal learning networks (ULNs) is discussed. The application of these two methods to a Photovoltaic (PV) supplied, separately-excited DC motor with a constant load torque is also studied. The simulation results of the proposed robust control and stability analysis method showed that the robustness of the DC motor system is improved and its stability can be analyzed easily.