气浮试验台重力卸载精度分析

Gravity Unloading Precision Analysis of Air Bearing Facility

针对中继卫星天线驱动机构,提出了一种在地面进行分级同步重力卸载的气浮试验台,对卫星天线驱动机构的性能进行测试。介绍了分级同步重力卸载的机理和气浮试验台的结构,通过运动学动力学推导,计算了天线驱动机构两个关节的驱动力矩,通过对其运行状态进行分析,得到试验台稳定运行时的重力卸载精度影响因素,包括可调弹簧机构的弹簧力、水平轴负载不平衡、同轴度偏差、气足和气浮主轴黏滞阻力和花岗岩平台的水平程度。对各个影响因素进行详细的分析,确定其对重力卸载精度影响的程度,采用层次分析法,得到了气浮试验台的重力卸载精度。结果表明可调弹簧机构和水平轴负载的不平衡对重力卸载精度的影响较大,因此在试验台调试阶段需要对这两项进行微调,提高重力卸载精度。通过对试验台的测试,证明了重力卸载的有效性,同时得到各个因素对重力卸载精度的整体影响程度,与理论分析结果相符。

A hierarchical and simultaneous gravity unloading facility is proposed.This facility is presented with air bearing to unload the gravity on the ground for testing the tracking and data relay satellite antenna pointing mechanism.The unloading method and the configuration are described and the running state is analyzed.The torque of two joints of antenna pointing mechanism is calculated by deriving the kinematics and dynamics models.The parameters which affect the gravity unloading precision are found:The force of the adjustable spring mechanism,the unbalance of the horizontal load,the deviation of concentricity,the viscous resistance of air bearing and level degree of granite platform.Those parameters are analyzed in detail with the influence on the gravity unloading precision.The theoretical unloading precision is derived by hierarchy analysis.The spring force and the unbalance of horizontal load are main parameters which reduce the precision,so those two parameters should be adjusted specially to improve the gravity unloading precision.The effectiveness of the gravity unloading method is proved with the test of the facility.The reduction of gravity unloading precision by those factors is got and the results match the analysis.