面向飞机大部件调姿的PPPS机构球铰点中心位置闭环标定方法

PPPS机构球铰点中心位置对飞机大部件调姿精度有重要影响，为了解决当前常用的球铰点中心位置获取方式在精度或效率上的不足，提出一种PPPS调姿机构球铰点中心位置的闭环标定方法。首先，分析了球铰点中心位置误差与运动学逆解时定位器位移求解偏差的关系及大部件位姿变换参数对其的影响；然后，提出了基于关键特性结合奇异值分解几何意义的飞机大部件位姿参数快速求解方法，使位姿参数求解过程更加直观简捷，同时相较于常用的奇异值分解方法在精度上没有损失；利用一次调姿过程前后大部件位姿参数的变化和定位器的位移反馈，结合运动学逆解对球铰点中心的位置进行闭环标定，最后，以某型号飞机垂尾测试件为例验证了所提出方法的正确性和实用性。

Closed-loop calibration method of PPPS mechanism ball joint center position for posture adjustment of large aircraft components

Precision of ball joint center position in PPPS mechanism has a significant impact on the posture aligning accuracy of large aircraft components. The common method to get the position of ball joint center is poor at precision and efficiency. To overcome the shortage of current means, a closed-loop calibration method is proposed. The position error of ball joint center brings deviation to positioner displacement in backward transformation and the orientation transformation parameters also have an effect on the deviation. The relationship between positioner displacement error and its influencing factors is analyzed firstly to show the necessity of this paper. A new calculation algorithm of posture transformation parameters, which is simpler and more direct than traditional singular value decomposition (SVD) method, is presented based on the key characteristics (KC) and the geometric meaning of SVD method. Then the posture transformation parameters are computed before and after the aligning of large components by the use of the proposed algorithm. The calculated parameters and the positioner displacement feedback from numerical control system are utilized to calibrate the position of ball joint center. Finally, a test vertical tail of a certain aircraft is used to demonstrate the validity and practicability of the proposed methods.