Insufficient stiffness of industrial robots is a significant factor which affects its positioning accuracy. To improve the positioning accuracy, a novel positioning error compensation method based on the stiffness modelling is proposed in this paper. First, the positioning errors considering the end load and gravity of industrial robots due to stiffness are analyzed. Based on the results of analysis, it is found that the positioning errors can be described by two kinds of deformation errors at joints: the axial deformation error and the radial deformation error. Then, the axial deformation error is modelled by the differential relationship of kinematics equations. The model of radial deformation error is deduced through the recurrence method and rotation transformation between joints. Finally, these two models are transformed into a Cartesian coordinate system, and a positioning error compensation method based on these two models is presented. Simulations based on the finite element analysis are implemented to verify the positioning error compensation method. The results show that the suggested method can efficiently predict the positioning error according to the gravity and loads, so that the positioning accuracy of industrial robots can be improved with the proposed method.

中文翻译：

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基于刚度建模的工业机器人定位误差补偿

工业机器人的刚度不足是影响其定位精度的重要因素。为了提高定位精度，提出了一种基于刚度建模的定位误差补偿方法。首先，分析了由于刚性导致的考虑工业机器人的最终载荷和重力的定位误差。根据分析结果，发现定位误差可以用两种变形误差来描述：轴向变形误差和径向变形误差。然后，通过运动学方程的微分关系对轴向变形误差进行建模。通过递推法和节间旋转变换推导了径向变形误差模型。最后，将这两个模型转换为笛卡尔坐标系，并提出了基于这两个模型的定位误差补偿方法。进行了基于有限元分析的仿真，以验证定位误差补偿方法。结果表明，该方法能够根据重力和载荷有效地预测定位误差，从而提高了工业机器人的定位精度。