Gantry-type computer numerical control (CNC) machines are widely used in the manufacturing industry. A novel structure with moveable gantry is proposed to improve the traditional gantry-type machine structure’s disadvantage of taking up too much space. Geometric errors have direct impacts on the actual position of the tool, which significantly reduces the accuracy of machines. Errors of different components are always coupled and have uncertain effects on the total geometric error. Thus, it is essential to find an effective way to identify the dominant errors and do targeted compensation. First, a novel identification method using value leaded global sensitivity analysis (VLGSA) is proposed to find the dominant errors. In VLGSA, weighting factors which show the influence of the error range are used to modify the multi-body system (MBS) error model. Results show that the dominant errors in three directions respectively contribute 80%, 86% and 85% of the total error in their directions. Then, errors identified by VLGSA are modeled by least-square linear fitting and B-spline interpolation methods, respectively, according to the feature of error data. Finally, the models are applied in a new real-time compensation system developed on the Beckhoff TwinCAT servo system. Experimental results from the gantry-type CNC engraving and milling machine show the proposed method can help figure out the most dominant errors and reduce around 90% of the total error.

中文翻译：

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考虑重大误差的龙门式数控机床几何误差补偿的新方法

龙门式计算机数控（CNC）机器广泛用于制造业。为了克服传统龙门式机械结构占用过多空间的弊端，提出了一种新型的可移动龙门结构。几何误差直接影响工具的实际位置，这会大大降低机器的精度。不同零件的误差总是耦合在一起的，并且对总几何误差有不确定的影响。因此，必须找到一种有效的方法来识别主要误差并进行目标补偿。首先，提出了一种利用价值引导的全局敏感性分析（VLGSA）的新颖识别方法来找到主要误差。在VLGSA中，使用显示误差范围影响的加权因子来修改多体系统（MBS）误差模型。结果表明，三个方向的主要误差分别占其方向总误差的80％，86％和85％。然后，根据误差数据的特征，分别通过最小二乘线性拟合和B样条插值方法对由VLGSA识别的误差进行建模。最后，将模型应用于在Beckhoff TwinCAT伺服系统上开发的新型实时补偿系统中。龙门式数控雕刻铣床的实验结果表明，所提出的方法可以帮助找出最主要的误差，并减少约90％的总误差。根据误差数据的特征，分别通过最小二乘线性拟合和B样条插值方法对由VLGSA识别的误差建模。最后，将模型应用于在Beckhoff TwinCAT伺服系统上开发的新型实时补偿系统中。龙门式数控雕刻铣床的实验结果表明，所提出的方法可以帮助找出最主要的误差，并减少约90％的总误差。根据误差数据的特征，分别通过最小二乘线性拟合和B样条插值方法对由VLGSA识别的误差建模。最后，将模型应用于在Beckhoff TwinCAT伺服系统上开发的新型实时补偿系统中。龙门式数控雕刻铣床的实验结果表明，所提出的方法可以帮助找出最主要的误差，并减少约90％的总误差。