Dynamic Error Measurement for Large Machine Tools

Existing machine tool metrology methods measure the quasistatic errors of a machine tool and, thus, evaluate its static positioning accuracy. Yet machine tools are dynamic, they do not stop and pause in an effort to reach a programmed position. Additionally, current techniques do not identify all of the errors, many of which significantly impact the volumetric accuracy of the machine. Almost immediately once the machine is in use, the errors arising from thermal conditions, dynamic motions, and process loads overpower the alignment efforts. Therefore, at this time there is a large and growing need for real-time measurement of the performance of multi-axis machines at typical operational feeds and speeds on trajectories that are representative of actual parts. The goal of this feasibility study is to assess the capability of laser trackers to serve as a dynamic metrology device. To do this we will quantify the current capabilities and limitations of laser trackers, how these affect its functionality in the intended application, and outline next step for addressing these issues and making laser trackers more suited for real-time dynamic tracking of machine tool errors.