Fault tolerant control of the B747 short-period mode using progressive accommodation

Linear Quadratic design for the fault tolerant control of the short-period mode of the longitudinal model of the Boeing 747 aircraft is investigated. Under actuator faults, both fault accommodation and system reconfiguration procedures need the controller to be re-designed, which means solving the Algebraic Riccati Equation (ARE) associated with the post-fault system model. To overcome the risks of system instability and/or control inadmissibility, which result from fault detection and isolation delay, and computation time of the accommodated control, a progressive accommodation strategy, based on the Newton-Raphson algorithm for solving AREs, is used. The application shows the benefits associated with this approach.