Fault tolerant control of feedback linearizable systems with stuck actuators

Fault tolerant control of feedback linearizable systems with stuck actuators is studied in this paper. Once stuck, the faulty actuators cannot respond to the control inputs and have fixed constant outputs. The fault considered here is severe in the sense that the faulty system is no longer feedback linearizable. By constructing a nonlinear transformation and extending Chen's disturbance observer to a multi‐dimensional case, a generalized disturbance observer is developed for estimating the unknown constant outputs of the faulty actuators. Then, through integrating the generalized disturbance observer with a controller constructed by the famous cascade design method, a fault tolerant controller is obtained. It is proven that the fault tolerant controller ensures not only boundedness of the state of the faulty system but also satisfactory output performance. Finally, computer simulations are done using an inverted pendulum model to verify the effectiveness of the proposed method.