面向民机复合材料蒙皮维修曲面打磨的非对称并联机构性能研究

The composite material replacing of metal material has been widely used in the new type of civil aviation aircraft. The aircraft skin, as the easily damaged structure, needs to be grinded firstly in the maintenance. Due to the complicated free form surface structure of aircraft skin, which has the characteristic of nonuniform thickness, it is difficult to ensure the quality of grinding by manual grinding. Meanwhile, the man work has another disadvantage of longtime maintenance...To improve the efficiency of grinding, automatic equipment with high accuracy and stiffness, like asymmetrical parallel mechanism, should be developed into aircraft skin maintenance. This project intends to study a new kind of aircraft skin grinding method based on the new asymmetrical parallel mechanism. Based on the virtual work principle and the idea of substructure comprehensive, the semi-analytical stiffness model of flexible component will be established including hinge，branch chain and frame. The multi-objective function will be generated on account of the cerebellar model algorithm. According to the coefficient of variation of joint-space inertia, a new index will be proposed to evaluate the dynamic performance of stiffness. Thus the fast modeling strategy will be developed...Based on the MDH model and exponential product model, the exact static accuracy model will be established. In consideration of the hinge gap and the flexibility of the rods, based on the theory of the cantilever beam, the dynamic precision model will be established. Then, the accuracy compensation will be made by combining several optimization algorithms. A method of force-position flexible control will be proposed based on neural network. To keep the robustness of system, a performance index with the mixing of H2/H∞ will be introduced to form the intelligent flexible control strategy. Finally, an efficient grinding technical proposal of aircraft composite material skin will be obtained. The relevant study will provide the theoretical basis and technical support for the localization design of the maintenance equipment for composite components.

民航新型飞机广泛应用复合材料，蒙皮是易损伤结构，其维修时需要打磨。复合材料蒙皮是非均匀厚度的复杂空间自由曲面结构，现有人工打磨的质量不稳定且维修时间长，需要研发高刚度和高精度的自动化装备。非对称并联机构刚度和精度高，结构稳定质量轻，本项目拟深入研究基于该类新机构的打磨装备设计方法。基于虚功原理与子结构综合思想，考虑铰链、支链和机架弹性，建立半解析刚度模型。引入小脑模型算法生成多目标函数，改进联合空间惯性系数，提出新型刚度性能评价指标，形成整机刚度快速建模策略。提出修正MDH和指数积模型，建立静态精度模型。考虑铰链间隙和杆件柔性，基于悬臂梁理论，建立动态精度模型。综合分析误差源的影响，提出新型改进优化算法进行误差补偿。引入H2/H∞混合性能指标，进而形成力/位柔顺控制策略，得到基于非对称并联机构的复合材料蒙皮高效打磨解决方案。相关研究可以为复合材料构件的维修设备国产化提供理论依据和技术支持。

面向我国航空维修领域对飞机复合材料蒙皮高效打磨装备的重大需求，本项目提出新型非对称并联机构，用以代替手工对飞机蒙皮进行打磨，深入研究了机构的运动学、刚度、精度以及柔顺控制理论。. 提出一种新型的五自由度复合驱动并联机构，分析位置逆解。采用离散法计算可达工作空间，根据灵活度指标，确定了许用工作空间位置，完成了奇异性分析。.基于子结构综合思想，分别构建三条支链的刚度模型，最后线性叠加求得整机静刚度模型。将有限元仿真解与数值解对比，验证了刚度解析模型的合理性和有效性。基于机构自身特征和具体工作方式，提出了一种新型的方向综合刚度评价指标，引入层次分析法的指数标度准则，计算得到权重系数，建立了方向综合刚度评价指标，确定了整个工作空间内的刚度最小位姿。. 对一种新型三自由度非对称并联机构在误差建模、精度分析和精度综合等方面进行了深入的研究，以提高动平台的工作精度。考虑非对称空间结构，通过创建不可补偿误差源与末端的位姿误差的映射模型，构造了灵敏度系数和全局灵敏度评价指标。采用基于Sobol序列的拟蒙特卡洛法（Sobol-QMC）进行了灵敏度分析，揭示了不可补偿误差对末端的位姿误差的影响。构造了约束函数，将最小的制造和安装的成本作为优化的目标，进而建立了精度综合模型。采取遗传算法进行求解，得到了不可补偿误差合理的公差带，验证了优化结果的正确性。. 试制了原型样机。建立了系统动力学模型，根据关节运动角速度控制机器人完成蒙皮打磨，实验验证了模型的正确性。由于机械机构的控制精度受到打磨机器人运动时振动的影响，为了提高控制精度以及系统的鲁棒性，采用神经网络与力/位相结合的柔顺控制方法，从而提高在外界扰动影响下的系统稳定性。. 本项目相关研究可以为复合材料构件的维修设备国产化提供理论依据和技术支持。