Flight Control Technology Research For Heavy Cargo Extraction Of Supper Low Altitude Airdrop

Super low attitude airdrop technology can provide equipment and material support to enhancethe mobility capability of the force. Because the transport airplane is flying at low speed and lowaltitude during super low attitude airdrop, the aerodynamic characteristic of aircraft is lower, and thecargo extraction interferes with aircraft flying attitude and flight track. An unsuitable control mayinfluence the safety of flight.This paper, which bases on performance indexes of airdrop, studies the flight control technologyto restrain the impact of cargo extraction.Firstly, the transport longitudinal mathematical model of heavy cargo airdrop system is deducedand analyzed. Cargo extraction dynamics model is built. The paper analyzes the influence on flyingattitude of different drag force of extraction parachute in the case of no control. Secondly, the flightcontroller based on LQR control method is designed for longitudinal attitude keeping control, and anautomatic throttle controller is designed for keeping flight speed. Thirdly, the paper investigates a kindof important accident case, that of cargo be stuck at guide rail with opened extraction parachute, andthe fuzzy controller is designed in order to weaken transport’s attitude response to cargo extraction onfault state. At last, the paper analyses the performance indexes of climbing phase, and a trajectorytracking controller based on robust H∞control method is designed. Moreover, a switch method isstudied in order to suppress transient on switching phase of control laws. The results of simulationshow that the trajectory tracking controller can guarantee the robustness and achieve the desiredeffects under the normal and fault condition.