Improvements of an Embedded System for Measuring Supended Particles

Abstract: Particle suspension is a phenomenon when solid particles get trapped in a liquid. This phenomenon is a common occurrence in the water treatment industry. It is typically measured continuously throughout the treatment process to ultimately ensure high water-quality. Cerlic Controls AB specializes in developing sensors for the water treatment industry and have been doing so since 1977. Cerlic Control's sensors are used within the various stages of water-purification. The type of sensor central to this project uses transmission of light to determine a concentration of suspended particles. This project describes the development-process for one of Cerlic Controls existing embedded systems. The embedded system is undergoing a modernization process where the electronics and software are updated to a more modern design. This report describes the improvements to the measurement range while maintaining the same or improved resolution. These improvements are mostly performed by modern electronics and more advanced signal processing techniques in comparison to the previous implementation. A large portion of the previous implementation's software was split over two embedded systems due to limitations in processing power. This modern version focuses on bringing these two systems into one. The sensor's microprocessor has been replaced with a more modern higher performance alternative which allows all computations to be performed in the sensor. Linearity and stability are key aspects defining system performance. Optical filters block a certain amount of light and are heavily used in verification of performance. Suspensions using activated carbon were also used to evaluate the measurement range. The results of the project were largely successful. An initial implementation was achieved with optimistic results, but further work must be done before the sensor is ready for use in industry.