动力翼伞系统拟坐标形式的多体动力学建模

精准的翼伞空投着陆需要更接近实际的动力学模型。采用拟坐标形式的Lagrange方程，提出反映翼伞连接方式和相对运动的翼伞多体动力学建模方法。针对翼伞系统稳定飞行的运动特性，将其处理为伞衣、伞绳和载荷等多刚体系统。利用多项式形式表示伞衣下拉后缘时的气动力，附加质量影响处理为等效力，各体平动速度和角速度作为拟坐标，建立无约束形式的多体动力学方程。以某小型翼伞系统为例，仿真分析了单刚体和多刚体模型在下拉后缘、突风扰动和不同吊挂模式下伞衣与载荷的运动特性。仿真结果表明，所建模型有效反映了翼伞系统的相对运动，可通过改变连接方式提高载荷运动的稳定性。

Multibody Dynamics Modeling of Powered Parafoil System Using Equations with Quasi-coordinates

An eighteen-degrees-of-freedom model of powered parafoil system was developed using hybrid Lagrange's equations of motion in terms of general quasi-coordinates, which is used to simulate the relative motion and connection of a payload with respect to a parafoil. Considering the feature of stable flight phase, the parafoil system is taken as three major parts， including canopy, payload and cord, and the aerodynamic forces on the canopy controlled by brake deflection are expressed in the form of polynomial equations, while the apparent mass and inertia effects are also regarded as external forces. In deriving the equations of motion by the Lagrange approach, the angular and translational velocities of each body are taken as general quasi-coordinates. An illustrative example is used to analyze the gliding and turning flight of the parafoil system, the relative motion simulations of single and multibody dynamic models are investigated for the different cases of design rigging length，change in deflection，and wind gust compared to the 6 DOF system. Results show that the proposed model can reflect the relative motion of parafoil system，and the oscillatory response is preferred to be reduced by use of payload connection.