Hybrid adaptive control for gust load alleviation

This paper develops a hybrid adaptive control (HAC) framework based on fast block least mean square (FBLMS) algorithm for gust load alleviation (GLA). Currently, the GLA control system is usually focusing on the alleviation of structural vibration of aircraft caused by turbulence perturbation. However, the conventional GLA control system could become useless as we need to focus on the alleviation in a relatively short period while the intensity of atmospheric turbulence changes fast. FBLMS algorithm exploits the computational advantage supported by a fast convolution technique which is known as the overlapped save method that relies on fast Fourier transform (FFT) algorithm for its implementation. With the proposed approach, an adaptive filter based on FBLMS algorithm is implemented as an outer adaptive feedforward controller which could cooperated with an inner proportional-integral-differential (PID) based feedback controller to suppress the aircraft vibration at every time step. With this algorithm, the HAC system could be able to take into account both the convergence rate and control accuracy at the same time. As a consequence, aircraft structural vibration could be alleviated in a relatively short time while the stability of whole system is guaranteed. A large transport aircraft dynamic model will be used to test the feasibility of the proposed HAC algorithm.