Sensor motes for the exploration and monitoring of operational pipelines

We report on a first field test in which miniaturized sensor motes were used to explore and inspect an operational pipeline by performing in situ measurements. The spherical sensor motes with a diameter of 39 mm were equipped with an inertial measurement unit (IMU) measuring 3-D acceleration, rotation, and magnetic field, as well as an ultrasound emitter. The motes were injected into the pipeline and traversed a 260-m section of it with the flow of water. After the extraction of the motes from the pipeline, the recorded IMU data were read out for the off-line analysis. Unlike dead-reckoning techniques, we analyze the IMU data to reveal structural information about the pipeline and locate pipe components, such as hydrants and junctions. The recorded data show different and distinct patterns that are a result of the fluid dynamics and the interaction with the pipeline. Using the magnetic data, pipe sections made from different materials and pipe components are identified and localized. A preliminary analysis on the motes' interaction with the pipeline shows differences in pipe wall roughness and locates structural anomalies. The results of this field test show that sensor motes can be used as a versatile and cost-effective tool for exploration and inspection of a wide variety of pipelines.