一种三自由度并联动力头—A3头的运动学标定方法研究

发布时间：2018-06-05 20:23

本文选题：三坐标动力头 + 运动学标定　；参考：《天津大学》2012年硕士论文

【摘要】：本文密切结合飞机大型结构件高速铣削加工的需求,系统研究了一种具有我国自主知识产权的新型三坐标并联动力头——A3头的运动学标定问题。内容涉及A3头的运动学分析、可将影响动平台位姿精度的可补偿与不可补偿误差源有效分离的误差建模方法、基于球杆仪信息检测的运动学标定技术,及其计算机仿真与实验验证。主要研究成果如下: 在建立3-RPS并联机构位置正逆解模型的基础上,基于矢量链法提出建立该机构全误差模型的建模方法,该方法通过将误差闭环方程向支链驱动与约束方向投影,进而获得末端位姿误差与支链几何误差源的线性映射模型,具有建模思路清晰,且可有效分离可补偿与不可补偿误差源,并具备一定的通用性的优点。在此基础上,通过灵敏度分析,为抑制末端不可补偿误差的零部件公差设计提供了理论依据。建立基于球杆仪信息检测的运动学标定模型,并根据误差源特征提出一种具有分层递阶格式的运动学标定方法,该方法首先识别出初始位形的支链零点误差,其次利用球杆仪识别其它几何误差源。鉴于利用该方法识别出的误差源处于同一数量级,进而提高了辨识结果的置信度。提出了基于修正系统输入的误差补偿策略,并以几何误差的可辨识性及辨识的抗扰动性为依据规划测量位形。计算机仿真结果表明,采用本文提出方法在理论上具有良好的鲁棒性。以天津大学自主研发的A3头样机为对象,开展运动学标定实验研究。实验结果表明,按照分层递阶的标定策略,经零点标定后刀具端点轨迹的圆度误差可由498μm减小至192μm;经球杆仪标定后刀具端点轨迹的圆度误差可进一步减小到55μm,由此证明了本文提出理论与方法的有效性。
[Abstract]:In this paper, the kinematic calibration of a new type of 3-axis parallel power head, A3 head with independent intellectual property rights in China, is studied in close combination with the requirement of high-speed milling of large aircraft structural parts. The content involves the kinematics analysis of the A3 head, which can effectively separate the compensable and uncompensated error sources that affect the position and attitude accuracy of the moving platform, and the kinematics calibration technology based on the information detection of the ball rod instrument. And its computer simulation and experimental verification. The main findings are as follows: On the basis of establishing the forward and inverse solution model of the position of 3-RPS parallel mechanism, based on the vector chain method, a modeling method for establishing the full error model of the mechanism is proposed. By projecting the error closed loop equation to the direction of driving and constraint of the branch chain, the method is proposed. The linear mapping model of the end position error and branch chain geometric error source is obtained, which has the advantages of clear modeling idea, effective separation of compensable and uncompensated error sources, and generality. On this basis, the sensitivity analysis provides a theoretical basis for the design of component tolerance which can restrain the uncompensated error of the end. The kinematics calibration model based on the information detection of the ball rod instrument is established, and a kinematics calibration method with hierarchical format is proposed according to the characteristics of the error source. The method first identifies the zero point error of the branch chain of the initial configuration. Secondly, other geometric error sources are identified by using the ball rod instrument. In view of the fact that the error source identified by this method is of the same order of magnitude, the confidence degree of the identification result is improved. An error compensation strategy based on modified system input is proposed, and the configuration measurement is based on the identifiability of geometric errors and the anti-disturbance of identification. The computer simulation results show that the proposed method is robust in theory. An experimental study on kinematics calibration was carried out with A 3 prototypes developed by Tianjin University. The experimental results show that according to the hierarchical calibration strategy, After zero calibration, the roundness error of tool end trajectory can be reduced from 498 渭 m to 192 渭 m, and the roundness error of tool end trajectory can be further reduced to 55 渭 m after calibrating by ball rod instrument, which proves the validity of the theory and method presented in this paper.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH113.22

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