Robust flight control design for the HIRM via linear quadratic methods

In this chapter the application of the LQ based techniques to the HIRM design problem is considered. The design of the proposed controller is performed in two steps: a) synthesis of a controller for the longitudinal dynamics; b) synthesys of a controller for the latero-directional dynamics. Both controllers implement a model following static output feedback control action designed by an LQ approach; the design accomplishes some optimality criteria in order to achieve the performance and robustness requirements. Moreover the control scheme is completed by the compensation of the physical nonlinearities, a feedforward control action, some demand shaping filters and a switching logic based on the angle of attack and on the Mach number. Most of the design requirements are easily satisfied; some others need a heavier tuning of the controller design parameters. A procedure to tune such parameters, formulated in terms of an optimization problem, is proposed. Simulation results are also provided at the end of the paper.