| A newly developed system for measuring and reducing machine tool error is introduced. The importance of reducing machine tool error is discussed, particularly in the lacking area of multi-dimensional error. Current machine tools do not account for multi-axis error, and do not measure error close to the point of contact between the work piece and the tool, so a system was developed that does just that. This system includes a two-dimensional holographic laser scale with a resolution of 62.5 picometers in each dimension, and software that was written specifically for this purpose. The system uses NURBS to approximate error from repeated measurements of machine trajectories, and creates altered trajectories which attempt to compensate for that error. As wear occurs over time, the system compensates by further altering the trajectories that are provided to the machine tool. Testing was performed on a nano-scale 3-axis machine tool. The experimentation showed significant error reduction when the environment is unchanged, and a mix of experimentation and simulation showed promising results for the dynamic error compensation functionality when the temperature was lowered to approximate a change in the error profile, similar to what might be caused from wear. |
