Multi-sensor geometry measurement on large-scaled gears

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New dimensional measuring systems are essential to keep pace with the raised requirements concerning production tolerances. The needed dynamic range of the measurement system is steadily increasing for applications of large volume metrology. For large-scaled gears, for instance, the tolerances increase with increasing diameter and module, but the ratio of needed measurement uncertainty and measuring volume decreases. Relating to the diameter, the required measurement uncertainty for assessing the total profile deviation of a large-scaled gear has to be one order of magnitude less than for a small gear. Furthermore, coordinate measuring machines and gear measuring instruments quickly reach their limits when measuring large-scaled gears. They are designed for a serial data acquisition and provide only a limited measuring volume. Thus, these devices are slow and hardly scalable. Current measuring systems for large volume metrology are either designed for serial data acquisition to some extent or do not provide the required measurement uncertainty.The intended project addresses the challenges of the dimensional measurement of large objects concerning the dynamic range and the scalability of the measuring system as well as the logistic effort and measurement time. The objective is to introduce a measuring system for the dimensional measurement of large objects using the example of large-scaled gears by combining a consequent model-based approach with a multi-sensor setup of optical distance sensors. Due to its modular architecture, the multi-sensor system can be easily adapted to the required measuring volume. Therefore, it is well suited for the measurement of large objects or as an in-situ measuring system. The capability of simultaneously acquiring multiple points on the object's surface by means of fast sensors reduces the measuring time.The focus of this project lies on the model-based evaluation of a form parameter of the actual gear geometry (base diameter) and on an optimal design of the multi-sensor system, based on a measurement uncertainty analysis. As a result, for a measuring object with a diameter of 2 m, an uncertainty of the form parameter < 5 µm should be reached. The required dynamic range of the individual distance sensors is also a subject of the research, as increasing the measuring range typically goes along with an increased measurement uncertainty. Thus, it should be clarified whether the location of the measuring zone could be quickly tracked with adaptive optic components without increasing the measurement uncertainty. The characterized multi-sensor system, which is based on optic sensors, will be validated by means of an existing large coordinate measuring machine. Moreover, it will be analyzed for the first time, whether and how both the measuring system and the model-based evaluation can be extended to more complex geometries.