Reliable mixed L2/H∞ fuzzy static output feedback control for nonlinear systems with sensor faults

This paper is concerned with the design of reliable mixed L-2/-H-infinity static output feedback (SOF) fuzzy controllers for nonlinear continuous-time systems with complete sensor faults. The Takagi and Sugeno (T-S) fuzzy model is employed to represent a nonlinear system. A sufficient condition for the existence of reliable mixed L-2/ H-infinity SOF fuzzy controllers is presented in terms of a set of quadratic matrix inequalities (QMIs), which not only guarantees that the closed-loop fuzzy system satisfies a desired H-infinity disturbance attenuation constraint for all admissible operating regimes (including the normal and sensor fault cases), but also provides different upper bounds on the L-2 performance criterion for different operating regimes. A suboptimal reliable fuzzy controller is obtained by the proposed iterative linear matrix inequality (ILMI) algorithm for minimizing the normal L-2 performance bound, while maintaining acceptable lower levels of the bounds in the sensor fault cases. Finally, a numerical example is given to illustrate the effectiveness of the proposed design method. (c) 2005 Elsevier Ltd. All rights reserved.