Output feedback adaptive fuzzy control of uncertain MIMO nonlinear systems with unknown input nonlinearities
1Department of Electrical Engineering, Faculty of Engineering, University of Guilan, Rasht, Iran.
ISA Transactions
|August 9, 2014
Summary
This study introduces an adaptive fuzzy controller for uncertain nonlinear systems with unknown input nonlinearities like hysteresis. The controller estimates system states using an observer, ensuring stability for complex systems.
Area of Science:
- Control Engineering
- Nonlinear System Theory
- Fuzzy Logic Systems
Background:
- Controlling uncertain multiple-input multiple-output (MIMO) nonlinear systems with unknown input nonlinearities (e.g., backlash-like hysteresis, dead-zone) is challenging.
- Existing methods often require full state availability or struggle with unknown nonlinearity gains.
- Fuzzy systems offer a powerful tool for approximating unknown nonlinear functions.
Purpose of the Study:
- To propose an adaptive fuzzy output feedback controller for uncertain MIMO nonlinear systems.
- To address unknown input nonlinearities and their unknown gain functions.
- To develop a state estimation method for systems where states are not directly available.
Main Methods:
- Utilized fuzzy systems based on the universal approximation theorem to approximate unknown nonlinear functions.
- Designed a state observer using strictly positive real (SPR) theory for state estimation.
- Incorporated an adaptive robust structure to handle fuzzy approximation errors and external disturbances.
- Employed the Lyapunov approach to guarantee semi-global asymptotic stability.
Main Results:
- Successfully developed an adaptive fuzzy output feedback controller for the targeted class of systems.
- Demonstrated state estimation without requiring direct state measurements.
- Achieved guaranteed semi-global asymptotic stability of the closed-loop system.
- Validated the controller's applicability through simulation results.
Conclusions:
- The proposed adaptive fuzzy output feedback control strategy effectively handles uncertain MIMO nonlinear systems with unknown input nonlinearities.
- The observer-based state estimation and adaptive robust structure provide a robust solution.
- The method ensures system stability and demonstrates practical applicability.
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