A spatial grid point compensation method for a one-translational two-rotational power head

Positioning accuracy is an important index used to indicate the accuracy of the moving parts in a machine tool under the control of CNC system. In order to improve positioning accuracy, error compensation is needed. Existing error compensation methods include model compensation and non-model compensation. However, due to the simplification of the error mapping model, some error parameters cannot be mapped to the model, so only part of the error parameters can be modified, and the compensation result is not ideal. In the present work, based on the thinking method of finite element, a non-model compensation method is used to compensate for the geometric error of a one-translational two-rotational (1T2R) power head (which is independently developed by Tianjin University). First, the pose error prediction model will be established, and the error of any point in the workspace can be predicted. The input correction method is then proposed to compensate for the pose error. Finally, both the proposed error prediction model and error compensation method are verified by simulation and experiment, and the results show that the proposed method can reduce the error of this 1T2R power head.