扁簧式起落架柔性变形的实时状态空间描述

Real time description of flexible deformation for leaf spring landing gear by state space method

根据无人机地面动力学分析对扁簧式起落架动力学模型的要求,提出了该起落架柔性变形的建模方法。首先,基于模态分析相关理论,通过调整刚度矩阵等效边界约束条件,获得扁簧式起落架的约束模态数据,并采用模态缩减简化模型;然后,采用模态坐标变换解耦振动微分方程,建立状态空间模型描述扁簧式起落架的动力学特性;最后,设计了静力学、动力学仿真测试以及扁簧落震实验对所建扁簧状态空间柔性模型进行验证。结果表明:静力条件下,状态空间模型与有限元软件静力分析结果仅有0.07%的误差,验证了柔性模型计算的准确性;另外,包含柔性状态空间模型的落震仿真模型的仿真步长为1ms,与落震实验结果的误差小于5%,满足飞行仿真的要求。实验显示,提出的柔性建模方法可为多体动力学刚柔混合模型中柔性模型的建立提供参考。

According to the requirements of Unmanned Aerial Vehicle（UAV）ground dynamic analysis, a leaf spring landing gear dynamics model was proposed to accurately reflect the dynamic characteristics of leaf spring deformations.On the basis of modal analysis,the leaf spring landing data were obtained by using the finite element method through modifying stiffness matrix and the model was simplified by modal reduction.After dissolving decoupling vibration differential equations by modal coordinate transformation,a state space model was constructed to describe the dynamics of the leaf spring landing gear.Finally,statics,dynamics simulation tests as well as the leaf spring drop experiments were designed to validate the flexible model.These results demonstrate that the results from state-space model and from finite element software static analysis have only 0.07%error under static conditions.The deviation of drop simulation with this model from real drop experiment results is about 5% when its real-time simulation step is 1ms,which satisfies the flight simulation requirements.