针对捆绑运载火箭姿态运动中由结构参数变化、内外干扰和弹性频率摄动引起的姿态控制问题,基于动态补偿线性化和系统辨识的思想,设计了一种基于微分估计和弹性频率辨识的运载火箭姿态控制器。该控制器由刚体姿态控制器和自适应弹性滤波器两部分组成。首先,通过微分器利用姿态测量信息估计因参数变化、运动耦合和内、外干扰引起的不确定项用于动态补偿,结合分数阶PDμ控制实现对火箭刚体姿态运动的控制。其次,根据箭体刚体运动与弹性振动在频率特性上的差异,利用控制输入和姿态输出采样信号辨识姿态传递函数参数,计算弹性振动频率,据此动态调整陷波滤波器中心频率,实现对弹性振动的自适应抑制。最后,通过仿真验证了上述设计的可行性,结果表明所设计的控制器具有较强的抗干扰性和鲁棒性,能够实现对一阶弹性振动的动态抑制,具有一定的工程参考价值。
Strap-on launch vehicle attitude control is a complex nonlinear problem that is compounded by several factors such as aerodynamics modeling uncertainties, internal/external disturbance and elastic frequency perturba tion. An attitude controller of strap-on launch vehicle based on dynamic compensation linearization theory and elastic frequency identification is presented. The controller contains a rigid body attitude controller and a adaptive e- lasticity filter. The rigid body attitude controller that augments differential compensator which is used to estimate and compensate impact of parametric uncertainties, movement coupling and disturbances by taking advantage of the in- formation of gyros and attitude sensors, to a fractional-order PD~ controller is implemented. Considering the fre- quency difference between rigid body motion and elastic vibration, sample signals of controller and attitude sensor output are utilized to identify elastic frequency. The adaptive elasticity filter dynamically adjusts the center frequency of notch filter according to the identification result to suppress elastic vibration. Validation of the design is done by numerical simulation. Simulation results show that the controller exhibits better dynamic performance, stron- ger robustness and elasticity restrain ability.