变重量/重心飞机建模及姿态控制律设计

为解决飞机在重量、重心变化下的姿态控制问题,从相互作用力的角度将重量、重心的变化转化为干扰力和干扰力矩,提出并建立了变重量/重心飞机的一般动力学模型和重量、重心特性模型.该模型可以反映重量、重心动态变化与飞机运动的耦合,解决了现有模型无法处理飞机重心动态变化的问题.在姿态控制律设计上,提出了针对飞机重量、重心变化的干扰观测补偿控制器结构,将重量、重心变化转化为干扰输入,采用比例积分观测器对重量、重心变化引起的干扰力和力矩进行观测,并将观测值解算为补偿信号引入自动驾驶仪,设计了纵向姿态的干扰补偿控制器.以运输机重型货物空投为背景的计算机仿真结果表明:该模型可以准确反映飞机在重心变化各个阶段的动力学特性;在观测器的补偿指令作用下,俯仰角对重量、重心变化的响应波动远小于未加补偿的情形,满足精确姿态控制的需要. 

Modeling and attitude control of aircraft with variations in mass or center of gravity

To solve the attitude control problem of aircraft with variations in mass and center of gravity (CG), a general model, including the dynamics and mass/CG variation properties, for such aircraft was established with the variations converted to disturbance forces and moments. This model was able to reveal the dynamic couplings between the CG shifts and aircraft motions, and the induced disturbances. For the attitude control of such aircraft, with variations in mass and CG treated as unknown disturbance inputs, an observation and compensation framework was proposed. The longitudinal attitude controller was then designed within this framework based on the proportional-integral observer (PIO) which estimates the disturbance force and moment inputs caused by mass and CG variations. The PIO compensation command was added to the regular autopilot. In the example of heavy load airdrop on cargo aircrafts, computer simulation demonstrated the proposed model could accurately reflect the aircraft-s dynamic responses in every stage of mass/CG variations, and pitch attitude response was greatly improved compared with controller without PIO compensation command and met precise attitude control requirements