| This thesis is devoted to nonlinear control and state variable estimation of a typical underactuated mechanical system, called "Pendubot ".; In most cases, the controllers applied to mechanical systems require information of all states for calculating the feedback control signal. For the Pendubot, states are comprised of joint angular positions and velocities. The joint angular positions could be measured accurately. However, the joint angular velocities are obtained either by differentiating the measured joint angular positions or through tachometers in practical situations. In both cases, the velocity signal is contaminated by noise. This degrades the performance of closed-loop Pendubot system.; The main focus of this thesis is on how to accurately estimate the joint angular velocities of the Pendubot. To develop advanced observers, model based approaches are considered. High-gain observer (HGO) and sliding mode observer (SMO) are designed and applied respectively. In order to fully investigate the effect of these two observers on the Pendubot, controllers based on each of them are applied to the Pendubot system in both simulation and real-time implementation. (Abstract shortened by UMI.)... |
