Control Allocation Based Sliding Mode Fault Tolerant Control

This paper describes a novel fault tolerant control using robust sliding mode control strategy. This scheme can also be employed as actuator redundancy management for over-actuated uncertain linear systems. In contrast to many existing methods in the literature that assume the control input matrix is not of full rank such that it can be factorised into two matrices, this scheme can be applied to systems whose control input matrix has full rank. The so-called virtual control, in this scheme, is designed to be robust against uncertainties emanating from visibility of the control allocator to the controller and imperfection in the estimated effectiveness gain. Then using a static real-time control allocator, the obtained virtual control signal is redistributed among remaining (redundant or non-faulty) set of actuators. The proposed scheme is a unified, control allocation-based fault tolerant control which does not need to reconfigure the control system in the case of actuator fault or failure. The effectiveness of the proposed schemes is discussed with a numerical example.