Robust control of underactuated inverted pendulum system in presence of unknown disturbances

In this paper deals with an observer-based robust control for non-linear underactuated system in presence of unmeasurable disturbances caused by nonlinearities. One advantage of the implementation of the proposed controller is that the trade-off between the tracking input and the suppression of the unmeasurable disturbance, caused by the backlash or other nonlinearities, can be independently treated in the process of the control system design. This, additionally, leads to reducing the effort of obtaining a highly accurate system model-the uncertain part of the model may be treated as a disturbance and its effect on the system dynamics can be compensated. Simulation and experimental results show the applicability of the controller.