六自由度运动模拟器精度分析

随着载人航天技术的发展,空间对接技术已成为各国十分关注的问题。空间对接技术是建立载人空间站必须解决的关键技术,也是我国航天事业进一步发展所迫切需要解决的问题。为了有效掌握载人航天技术,并针对对接系统研制以及性能测试中需要解决的关键技术,对空间对接过程半物理仿真试验系统进行研究是非常必要的。六自由度运动模拟器作为空间对接过程半物理仿真试验系统的关键设备之一,其位姿误差直接影响整个系统的仿真精度。因此,提高六自由度运动模拟器的位姿精度对于空间对接过程半物理仿真试验研究具有十分重要的意义。为解决六自由度运动模拟器的位姿精度保证问题,本文密切结合空间对接过程半物理仿真技术的需要,针对提高六自由度运动模拟器位姿精度的关键问题——精度设计和运动学标定技术进行了深入的研究。本文利用机器人学中的齐次坐标变换方法,以哈尔滨工业大学电液伺服仿真及试验系统研究所研制的六自由度运动模拟器为结构模型,将其各条分支链作为假想的单分支链,根据运动学方程以及并联机构的环路特性,建立了六自由度运动模拟器的位姿误差模型。利用此模型,可以对六自由度运动模拟器的位姿精度进行评估,并分析了六自由度运动模拟器位姿误差的标准差在工作空间内的分布规律,为进一步提高六自由度运动模拟器的位姿精度提供了理论依据。本文针对六自由度运动模拟器位姿的测量问题,提出了利用三坐标测量机测量运动平台上三个标准球对固定平台上三个标准球的距离,然后通过计算来确定六自由度运动模拟器的位姿。详细地分析、研究了位姿测量误差对三坐标测量机的测量误差和固定平台上三个标准球的位置误差的敏感性。推导出了三坐标测量机的测量误差、固定平台上三个标准球的位置误差对位姿测量误差的函数,发现只要适当地增大固定平台上三个标准球之间的相对距离,就能够有效地降低三坐标测量机的测量误差和固定平台上三个标准球的位置误差对位姿测量的影响,从而提高了位姿测量的准确性。本文研究了六自由度运动模拟器的外部标定技术,提出了基于运动学正、反解的外部标定方法,并完成了全部标定计算工作。首先,以六自由度运动模拟器运动学反解模型为基础,建立了标定模型,通过最小二乘算法和迭代算法求解六自由度运动模拟器的结构参数。对影响该标定算法计算精度的因素进行
工业羊毛毡
Along with the rapid development of manned space activities spacecraft, docking technique have become the problem noticed. It is the key technique to be solved for space station. It is also an urgent problem to be solved for developing our national space project. According to the need of developing and testing of the docking mechanisms, it is necessary to research on the Hardware-in-the-loop doching simulation system. The 6-DOF motion simulator is one of the most pivotal equipments in the spacecraft docking simulation, and the precision of the simulation system is determined by its pose error. So it is significant to enhance the simulation precision by improving pose accuracy of 6-DOF motion simulator. The dissertation deals with one of the most important techniques in developing 6-DOF motion simulator used in spacecraft docking simulation, accuracy design and kitic calibration technology, which can improve pose accuracy of the motion simulator.The 6-DOF motion simulator made by IEST is taken as the structural model, by treating each sub-chain of 6-DOF motion simulator as a joint-link train, thus the pose error model in which structural paprameter errors are considered is established from the kitic equations and the loop properties of parallel structure. The model can be used to evaluate the pose accuracy. The distributing rules of pose error’s STD in the workspace are obtained. The results provide the academic bases for improving the pose accuracy of 6-DOF motion simulator in the future.A method is developed to measure the pose of 6-DOF motion simulator, which mainly measures the distance from three standard spheres on the moving platform to three standard spheres on the base platform by coordinate measuring machine, after that calculates the moving platform’s pose by the distances. The sensitivity analysis and discussion of pose measurement error caused by the measurement errors of coordinate measuring machine and by the coordinate errors of three standard spheres on the base platform has been done in detail. The pose measurement error formulas as function of the measurement errors of coordinate measuring machine and the coordinate errors of three standard spheres have been deduced and it has been discovered that larger relative diatances among the three standard shpheres will efficiently minimize the influence of the measurement error of coordinate measuring