An FDI Scheme For A Satellite Based On A Multivariable Super-Twisting Sliding Mode Approach

This paper proposes a super-twisting sliding mode observer structure for the multivariable case when many interdependent measurements are available. This structure is used to create a second order sliding mode observer to detect and isolate gyro faults for a satellite system. A least squares approach for an overdetermined system is used to detect the presence of a sensor fault, and once the fault is detected, isolation is attempted. A generalized bank of nonlinear observers based on multivariable super-twisting-sliding mode observers is designed to isolate the faulty sensor. The use of higher order sliding modes eliminates the chattering problem encountered in traditional sliding modes while retaining its robustness properties. The proposed design is verified on a nonlinear satellite model for various fault scenarios.