Interval Sliding Mode Observer based Fault Accommodation for Non-minimum Phase LPV Systems with Online Control Allocation

This paper proposes an interval sliding mode observer (ISMO) based sliding mode actuator fault accommodation (FA) framework for non-minimum phase linear-parameter-varying (LPV) systems involving online control allocation (CA) problem. Firstly, a specifically designed coordinate transformation is introduced to deal with the non-minimum phase issue. Then, for the transformed system, an ISMO is proposed to estimate the set of admissible values for the states of the faulty LPV systems. It is constructed based on the designed interval bounds for the scheduling-parameter-related uncertainties and fault-related items. The observer is designed by combining the interval observer and the sliding mode observer techniques. A fault-tolerant control (FTC) law with an online CA scheme is subsequently designed by stabilizing the proposed ISMO instead of the original faulty LPV system, which guarantees that the unmeasurable states of the original LPV system converge to zero asymptotically, the measurable outputs converge to zero in finite time, and further, the actual control efforts are allocated to all actuators optimally and satisfy prescribed performance. Finally, a simulation based on the inverter used in China Railway High-speed (CRH) is presented to illustrate the effectiveness of the proposed framework.