关节铰间隙对漂浮基星载天线扰动研究

Research on Disturbance of Joints with Clearance on Free-Floating Satellite Antenna

为了研究关节铰间隙对星载天线扰动,建立了铰间隙矢量矩模型,采用非线性弹簧阻尼及修正库仑摩擦建立了铰间隙碰撞力和摩擦力模型;进一步推导了理想铰和含间隙铰变拓扑结构的漂浮基星载天线多体系统动力学模型。通过接触碰撞判别准则,将系统的几何约束转化为力约束,使得系统无拓扑结构变化,便于系统的全局仿真。最后对理想铰与含间隙铰的漂浮基星载天线系统仿真分析,结果表明,较小间隙对星载天线位姿和指向影响很小,但极大增加关节的碰撞力,随着时间流逝,其位姿和指向精度偏差变大,但由于非线性阻尼的存在,碰撞力逐渐变小,最终保持接触状态。结论对星载天线指向精度的分析与控制具有重要的理论价值及工程实际意义。

In order to study the dynamic characteristics of free-floating satellite antenna with joint clearance,the joint clearance model is established based on a thorough geometric description of eccentricity vector. Then,the contact forces are evaluated by using the nonlinear spring-damp model and the friction forces are calculated by using modified Coulomb’s fric- tion law. Furthermore,the contact-impact criterion is used to transform the geometric constraints into force constraints,and no topology changed through adding and/or deleting kinematic constraint equations in the system to facilitate the global sim- ulation. Finally,the dynamic response of satellite antenna system is analyzed in consideration of the ideal joint and the joint clearance respectively. The simulation results indicate that antenna pointing accuracy is seriously affected by the existence of joint clearance. It can cause high peaks on the kinematics and dynamics characteristics of system due to contact-impact forces. However,the existence of non-linear damping in joints makes contact-impact forces smaller. The journal and the bearing are in continuous contact finally. The conclusion would have important academic value and engineering significance for satellite antenna pointing accuracy analysis.