Online actuator reassignment for fault tolerant flight control

This communication considers the case in which some aerodynamic actuator failures occur when an aircraft performs the intended maneuver. The problem considered deals with online reassignment of the remaining effective actuators to continue performing the current maneuver safely. First, through analysis of a general nonlinear system, the concept of virtual inputs and fault tolerance is proposed and analyzed. Taking a pure roll maneuver as an example, the values of its virtual inputs can be computed through nonlinear inverse control approach. Then, a linear quadratic programming problem is formulated for actuator reassignment, to find a best utilization of remaining effective actuators, as well as taking into account various constraints for safety. Three fast solution approaches are studied to solve this reassignment problem. The simulation results show the feasibility of the proposed method. Finally, a general conclusion is drawn.