Robust Nonlinear Output Feedback Tracking Control of Single-Link Flexible Joint Robotic Manipulator System

Single link flexible joint robotic manipulators are highly nonlinear systems is being widely used in many industries which are most of the time suffer from external disturbances and dynamical parametric uncertainties. In this paper, robust nonlinear output feedback tracking control is designed for single-link flexible joint robotic manipulator system. The designed controller is based on the feedback linearization control technique which is opted owing to its simplicity. A conventional high gain observer is used to estimate the states, but it is sensitive to external disturbances and parametric uncertainties. To handle the aforementioned drawbacks, an extended order high gain observer is used which has the capability to eliminate the effects of external disturbances and parametric uncertainties. A feedback linearizing control technique is used to track the desired output of the robotic manipulator and extended order high gain observer is used for state estimations. The proposed controller and observers are validated using MATLAB simulations. The results show that the extended order high gain observer along with globally bounded feedback linearizing control perfectly tracks the trajectory of the system's output in the presence of external disturbances and parametric uncertainties. This robustness of the extended order high gain observer against external disturbances and parametric uncertainties makes it appropriate for practical implementation to the flexible joint n-link manipulators.