Observer-Based Adaptive Fuzzy Output-Feedback Tracking Control of MIMO Strict-Feedback Nonlinear Systems on Time Scales

This article attempts to study observer-based output-feedback tracking control problems of multiple-input multiple-output strict-feedback nonlinear systems (MIMOSFNSs) on time scales. If all nonlinear dynamics are known, the corresponding virtual and actual controllers are designed based on system output and observer states such that system output closely tracks the desired signal. If all nonlinear dynamics are unknown, they are approximated by introducing several Takagi-Sugeno fuzzy systems, then a fuzzy observer, the corresponding virtual and actual controllers, and novel parameter adaptive laws are proposed to achieve output-feedback tracking control for MIMOSFNSs on time scales. It is worth emphasizing that our control schemes are applicable to high-order high-dimensional MIMOSFNSs without using complex nonlinear transformations, and the contradiction of causality in the recursive control design can be avoided. Last but not least, since MIMOSFNSs have been investigated on time scales, our theoretical results can be appropriate for continuous-time MIMOSFNSs, their discrete-time counterparts and arbitrary combination of them. Finally, simulation studies are conducted to verify the validity of the proposed output-feedback tracking control schemes.