Robust control allocation with adaptive backstepping flight control

Abstract

For the enhancement of survivability and maneuverability, modern aircraft systems have redundant control effectors. Control allocation is a useful method for distributing control signals among the individual effectors. In order to implement a control allocation scheme, the control system is designed using two-step procedures. In the first step, the control law is designed by adaptive backstepping control. The second step is to design the control allocator. A robust control allocation method is presented in this paper, which is motivated from the concept of the worst-case robust approximation approach. By assuming uncertainties in the control effectiveness matrix, the worst-case robust control allocation problem is investigated. The proposed robust control allocation technique is compared with weighted least squares control allocation. In particular, nonlinear simulations demonstrate that the proposed robust control allocation method has satisfactory performance and robustness for the assumed uncertainties in the control effectiveness matrix.