Dynamical referencing of coordinate measurement machines and machine tools

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Subject of the proposed project continuation is the extension of the successful investigations on the enhancement of the dynamic properties in measuring machines and machine tools under preservation of the accuracy by combining holographic measurement principles with model-based controller design techniques.The developed and evaluated camera system will be extended in order to simultaneously track two luminous point markers in space with a single optical sensor. The goal is to achieve up to 500 acquired frames per second and a spatial resolution of approximately 1 um for the measured marker position using the established multipoint projection method with computer-generated holograms. This permits a precise and direct measurement of the relative position between tool and workpiece in measuring machines or machine tools for the first time. In order to ensure a high spatial resolution, ultra-precise calibration techniques which are also based on the holographic multi-point projection technique will be investigated, resulting in an improved signal-to-noise ratio.The novel measurement technique provides a direct determination method for the relative pose between tool and workpiece, but the temporal and spatial resolution of typically used encoders at the drive axes is still better. However, these encoders provide only an indirect measurement with a larger uncertainty since they are located at the drive axes. Thus, the fusion of the measurement signals from the camera system and the encoders is subject of the proposed project continuation, such that the decisive relative position between tool and workpiece can be obtained with both high spatial and temporal resolution for the first time. This estimate is used to establish a high-precision tracking control system. In the course of this, methods for improving the tracking accuracy by dual-stage actuators will be investigated.