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FAST望远镜的馈源支撑是一个跨度巨大的柔索牵引并联机构,其中可承载用于收集射电波信号的馈源接收机的馈源舱由六根并联的支撑钢索悬挂于空中,并随着6索的协调收/放可在空中大范围缓慢运动。由于支撑钢索的截面尺寸较大,在机构平衡状态下其自重不能忽略。其中一部分钢索还需要悬挂入舱的动力电缆和通讯光缆,因此馈源舱运动范围、馈源舱姿态、各索的张力和索的几何构形均存在着复杂的耦合关系。该文建立了支撑钢索和馈源舱的静力平衡方程,通过引入各索张力均衡分配的优化原则,对舱静力平衡方程进行了优化求解,并获得了各索张力和馈源舱姿态角在轨迹球冠面内的优化计算结果。从各索张力的优化计算结果可推导出各索张力的最大值、最小值和变化趋势。基于馈源舱姿态角的优化计算结果,并结合馈源接收机在焦点位置所必须达到的姿态角控制要求,估算了舱内的AB转轴机构所需要的最小姿态角补偿范围。该文最后分析了支撑塔高度和馈源舱的重心位置对于索张力和馈源舱姿态角在轨迹球冠面内的优化分布计算结果的影响。分析结果表明最大索张力对于支撑塔高度较为敏感且成反比,而舱姿态角对馈源舱的重心位置较为敏感。这两项重要参数均应在未来FAST的设计中进行优化。
The feed support for the FAST telescope is a large-span flexible cable-pulling parallel mechanism in which the feed compartment, which can carry a feed receiver for collecting radio-wave signals, is suspended in the air by six parallel supporting cables and, as 6 Coordination of cable collection / release can be a wide range of slow motion in the air. Due to the larger cross-sectional dimensions of the supporting cable, its self-weight should not be neglected at the equilibrium of the mechanism. Some of the cables also need to be suspended into the cabin of the power cables and communications cables, so the feed compartment movement range, the attitude of the feeder cabin, the tension of each cable and the cable geometry there are complex coupling relationship. In this paper, the static balance equation of supporting cable and feed compartment is established. By introducing the optimization principle of balanced distribution of each cable tension, the static equilibrium equation of the cabin is optimized and solved. Optimum calculation results of the angle in the coronal plane of the trackball. The maximum value, the minimum value and the change trend of each cable tension can be deduced from the optimization results of each cable tension. Based on the optimization calculation results of the attitude angles in the feed cabin and the attitude angle control requirements that the feed receiver must reach at the focal position, the minimum attitude angle compensation range required for the AB rotary shaft mechanism in the cabin is estimated. Finally, the paper analyzes the influence of the tower height and the center of gravity of the feed capsule on the calculation results of the optimal distribution of the cable tension and the attitude of the feed capsule in the spherical orbit of the trajectory. The analysis results show that the maximum cable tension is more sensitive and inversely proportional to the tower height, while the attitude of the cabin attitude is more sensitive to the gravity center of the feed cabin. Both of these important parameters should be optimized for future FAST design.