Application of probabilistic index of ride quality in multi-object control law synthesis for large civil aircraft

Abstract

Since the flight dynamic response of large civil aircraft is sensitive to the atmosphere turbulence inspiration which would significantly influence the ride quality and trajectory stability, a multi-object flight control law is designed in the current work, which can be easily applied to engineering. To consider the influence of structural dynamics, the flight dynamics equation is derived from the Lagrange method with inertial coupling neglected by considerable small deformation assumption of structural flexibility effect for the aircraft with traditional configuration. In the procedure of control law synthesis, constraints in both time and frequency domain are set in multi-objective synthesis techniques that should consider gust load alleviation and flying qualities which are introduced as requirements from damping ratio and natural frequencies of the dynamic system. To realize ride quality improvement in the control law synthesis, the probabilistic index is applied to emphasize the probabilistic characteristics of atmospheric turbulence intensity. The feedback gain for optimum effect on comfort improvement is obtained by genetic algorithm. A numerical model of large flexible aircraft is performed with the design procedure above, which comes to a trade-off between different requirements of flexible aircraft flight control law. Simulation results show that the response of gust can be reduced effectively, and the flying qualities were improved.