针对发动机谐振可能与箭体弹性振动之间发生耦合共振,从而引起姿态控制系统不稳定的问题,首先将发动机谐振特性简化为一个二阶环节,建立了包含发动机谐振方程的火箭姿态动力学模型;然后分析了发动机谐振对箭体模态极点频率和阻尼比的影响,并从理论上分析了出现负阻尼比时发动机和箭体模态间的耦合共振机理,在此基础上计算了导致姿态控制系统不稳定的发动机谐振频率边界;最后通过时域仿真验证了分析结果的正确性。结果表明,当发动机谐振频率较低时可能与箭体低阶弹性模态之间产生耦合共振,导致姿态角和姿态角速度出现振荡甚至发散现象,发动机谐振频率必须高于谐振频率边界最大值才能保证系统稳定。相关工作对姿态控制系统的设计具有一定价值。 Aiming at the problem that the resonance of the engine may be coupled with the elastic vibration of the rocket body, which leads to instability of the attitude control system. First, the resonance characteristics of the engine are reduced to a second-order link, and the rocket attitude dynamics model including the resonance equation of the engine is established. Then, the influence of engine resonance on the modal pole frequency and damping ratio of the rocket body is analyzed, and the coupling resonance mechanism between the engine and the rocket body mode in the presence of negative damping ratio is analyzed theoretically. Based on this, System instability of the engine resonance frequency boundary; Finally, the time-domain simulation to verify the correctness of the analysis results. The results show that when the resonance frequency of the engine is low, the coupling resonance may occur between the low-order elastic modes of the rocket body, resulting in the oscillation or even divergence of the attitude angles and the attitude angular velocities. The resonance frequency of the engine must be higher than the maximum of the resonance frequency boundary System stability. Related work poses a certain value to the design of attitude control system.