飞翼飞机易发生刚体短周期模态与机翼低阶弯曲模态耦合所致的体自由度颤振。飞行控制系统对飞机的短周期模态特性影响很大，因此考虑飞行控制系统的闭环体自由度颤振特性值得进一步研究。针对自主设计的颤振模型开发了相应的俯仰姿态保持控制律，综合运用风洞试验和仿真计算开展了相关研究，获得了不同刚体自由边界条件下的开环/闭环体自由度颤振特性，研究了闭环增益对体自由度颤振特性的影响规律，简要分析了影响机理。试验和仿真计算结果共同表明：俯仰姿态保持控制律明显地改变了俯仰模态阻尼的原有走势，闭环后的体自由度颤振特性变化明显。以开环颤振速度为基准，采用较小的比例回路增益KP或较大的微分回路增益KD，飞行控制律能增加飞行器俯仰阻尼，提高体自由度颤振速度，反之飞行控制律将导致颤振速度降低。就本文控制律而言，当KP<0.07或KD>0.2时俯仰姿态保持控制律能起到抑制体自由度颤振的作用。
Body freedom flutter, caused by coupling of the short period mode of the rigid body and the low order bending mode of the wing, easily occurs on flying wing aircraft. Since the flight control system has a significant influence on the short period modal characteristics of the aircraft, the closed-loop body freedom flutter characteristics considering the flight control system needs further study. In this paper, a pitching pose holding control law was developed for the self-designed flutter test model. The wind tunnel test and simulation calculation were used to conduct the research. The open-loop/closed-loop body freedom flutter characteristics under different free-free boundary conditions were obtained. The closed-loop gain on the flutter characteristics was studied, and the influence mechanism analyzed briefly. The results showed that the pitching pose holding control law obviously changed the original trend of modal damping, and the body freedom flutter characteristic of the closed-loop changed obviously. Based on the open-loop flutter velocity, using a smaller proportional loop gain KP or a larger differential loop gain KD, the flight control law can increase the pitch damping of the aircraft and the body freedom flutter velocity. Otherwise, the flight control law would reduce the flutter velocity. For the control law in this paper, when KP<0.07 or KD>0.2, the pitching pose holding control law can suppress the body freedom flutter.
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