A Non-Intrusive Ultrasonic Sensor System for Water Flow Rate Measurement

Ultrasonic technologies have established themselves as optimal solutions for water flow rate measurement thanks to the high reliability and efficiency they offer. However, the existing applications often require ultrasonic sensors to be embedded in pipes, i.e., intrusive, which significantly increases initial deployment and maintenance costs. Considering the volume of employment, one to each house, the water meters have to be designed in a way that the consumers can deploy and maintain them without any skilled labourer. Hence, this paper proposes a delta time-of-flight $(\Delta ToF)$ -based non-intrusive sensor system for plug-and-play ultrasonic water flow rate metering. After introducing the measurement theory and our proposed design, we experimentally evaluated the performance of three different ΔToF calculation methods in terms of memory and computation requirements through a dedicated testbed consisting of a closed-loop multi-pipe layout. The results helped us to determine the optimal $\Delta ToF$ method for the employed platform, which is then used to select the best sensor and housing setting that is operable even under the worst deployment conditions (pipe material, diameter). Compared to its intrusive counterparts, the proposed system achieved a sufficient level of precision $(\pm 5.7\%)$ and hence provided the possibility of replacing the conventional methods of intrusive water metering at the household level.