Research On Control Allocation Algorithms Based On Null-Space

This thesis takes over actuated aircrafts which have redundant actuators as the research object.Researchs and analyses are adopted on control allocation algorithm based on null-space and it’s applications in the design of flight control systems.The main works of this thesis are organized as follows:First of all,in the view of the current problems of Pseudo-inverse Along the Null-space(PAN)control allocation algorithm,the algorithm is developed to weaken the demand of the atuators’ physical constraint symbol.Because of the fact that the error of PAN control allocation algorithm is large when the desired moments’ vector is beyond the atteniable torque set,a control allocation strategy is proposed which combines direct allocation method with PAN algorithm.With the proposed strategy,the PAN algorithm can ensure certain accuracy outside the atteniable torque set and broaden the application scope of the algorithm.Secondly,on the basis of the developed PAN control allocation algorithm,a simple and efficient control allocation strategy with low time complexity is proposed.A recording vector is added during the process of solving the control allocation problem to handle with the problem that the desired torque is unatteniable.The recording vector is designed to record the control allocation solution which has minimum error between the solution and the desired torque vector.The low time complexity of the proposed strategy is ensured by set a small iteration times.At the same time,an integral sliding mode virtual controller is designed to deal with the situation that the desired torque is not atteniable.The controller is designed to handle the uncertainty caused by the error of torque and optimize the dynamic performance of the system.Finally,based on the PAN algorithm,the effect of effective control allocation algorithm to the over all system considering actuator constraints is examed in this paper.The influence which the control allocation algorithm with consideration of actuator constraints brings to the over all system is divided into matched and unmatched uncertainty.The matched uncertainty is processed by designing an integral sliding mode controller and the unmatched part is handled by a rubost controller based on Lyapunov’s direct method.The stability of the system with faults is ensured by small gain theory.