Modellbasierte Entwicklung pneumatischer Abstandssensoren für prozessintegrierte Messungen

Summary
The production metrology is one of the most significant areas in modern manufactoring processes. Basically, it consists of three main fields; material testing, operational testing and the most relevant field; the geometrical product specification. In general, three approaches are used to solve geometrical inspections. Tactile measurements are the oldest and most common applied technique to acquire information about a manufactured surface. Furthermore, optical instruments are installed in production lines to achieve high quality 3D measurements. This research work presents the investigation of pneumatic distance sensors, the third possibility to solve surface measurement tasks. Especially, due to the steady increasing requirement of high quality products, a continuous improvement of metrology applications is necessary. Additionally, today, geometrical inspections have to be closer to the manufacturing process then years ago to accomplish stable quality. Pneumatic sensors are excellent to solve those taks, since they are resistant to potential pollution and fluids on the measured surfaces. the self cleaning effect of this sensor type allows a simultaneous manufacturing and measurement process. Therefore, problems of manufacturing can be detected in-line and clarified faster compared to other sensor-concepts.
One of today´s problems is, that the knowledge of pneumatic sensors is comparatively small. In the last few decades, research has been carried out mainly on tactile and optical sensors. Applying pneumatic sensors to modern tasks, basic research has to be completed on this technology to fill this gap. Knowledge about spatial resolution and dynamic behavior exists in small quantities only. Further, the uncertainty of pneumatic sensors is rather described. Also manufactoring key parts of pneumatic sensors are not as stable as desired for this application. The presented research highlights this problems and possible solutions based on theoretical derivations and experimental research.
Pneumatic sensors are described by the theory of fluid mechanics. The underlying equations are five conservation equations. The mass conservation-, the three Navier-Stokes- and the energy-equation. Since the applied fluid in pneumatic sensor applications is gas, this equations can be simplified and summarized to a set of gas dynamic equations. Based on this fundamental theory, the characteristic curve of pneumatic sensors can be derived. Proving and improving this existent theory is one of the main tasks of the work presented.