Research On Atmospheric Disturbance Compensating Control Of Transport Aircraft Ultra-Low Altitude Airdrop

The TransportAircraft Ultra-Low Altitude Airdrop (ULAA) Technology can observably enhance the capability of long-range mobility and the speed of logistics support of Air Force. It still has realistic significances for the military to respond to various security threats, accomplish diverse military tasks and protect the expanding national interests. Because the transport aircraft flies in C phase while Ultra-Low Altitude Airdrop, high-accuracy flightpath tracking and attitude hold are required. During the course of Ultra-Low Altitude Airdrop, the transport aircraft has the following characteristics: First, the aerodynamic performance is not excellent any more and the capability of disturbance rejection declines. Second, the cargo's impact is very violent and the center of gravity of the aircraft shifts. Third, the probability of encountering turbulence, wind shear increases observably.Via research and simulations, disturbance compensation control methods are presented innovatively to slow down the effect caused by atmospheric disturbance. First of all, stochastic turbulence model, discrete gust model and low-level wind shear model which are usually used in flight control research are presented. Then the nonlinear six-degrees-of-freedom model of transport aircraft ULAA with atmospheric disturbance is provided. Based on this model, coupling movement of aircraft and disturbance is deeply analysed. After this, ULAA glide, flare, airdrop-pull up basic controllers and lateral basic controllers are designed using classical control theory. Based on the basic controllers, the longitudinal and lateral atmospheric disturbance compensating conrollers are designed. At last, fuzzy control theory is introduced and the ULAA longitudinal and lateral atmospheric disturbance compensating fuzzy conrollers are designed.After analysing the results of simulations, conclusions are presented that both classical controllers and fuzzy controllers can compensate the effects of atmospheric disturbance. The flight path and attitude could meet the exact demands of ULAA while the transport aircraft is disturbed by different kinds of atmosphere. Compared with each other, fuzzy controllers have stronger robustness and higher flight path tracking accuracy.