通过对类x-20高超声速飞行器的气动系数与高度、马赫数、攻角、侧滑角和舵偏角的关系进行分析,对各项气动系数进行了简化和拟合,并将舵偏增量视作控制输入,在此基础上建立了类x-20飞行器仿射非线性形式的控制模型,证明了它是可以输入输出精确线性化的,从而可以设计反馈线性化控制器.最后在存在大气密度、气动力矩系数和转动惯量不确定性情形下,针对原动力学模型进行闭环仿真研究,原动力学模型考虑地球旋转,气动数据直接从类x-20飞行器的气动数据表插值得到.仿真结果表明,所设计的控制律可以实现控制目标,具有较强鲁棒性.
The configuration of an X-20-1ike hypersonic vehicle is researched. By a deep analysis on the relationship of the aerodynamic coefficients with the altitude, Mach number, angle of attack, angle of sideslip and the deflection of the control surfaces, a series of simplified analytical polynomial functions of these variables are fitted. For the controller design, the increments of the control surfaces are treated as the control input. Based on the fitted polynomial expressions and the control inputs, an affine nonlinear model of the hypersonic vehicle is established. This control model is proved to be approximately linear- ized, thus the feedback linearization method could be designed. Under uncertainties of atmospheric den- sity, aerodynamic moment coefficient and the moment of inertial, the control law for the original dynamic model is simulated. Considering the effect of the earth rotation and the aerodynamic model, simulation of the original model is established by the coefficients lookup tables. The simulation results demonstrate that the control objectives can be achieved and the controller is proved to be robust.