UAV-enabled Measurement for Spatial Magnetic Field of Smart Rocks in Bridge Scour Monitoring

Foundation scour is the main cause of bridge collapses in the U.S. In 2011, the principal investigator (PI) proposed smart rocks with embedded magnets for bridge scour monitoring. Once deployed around a bridge pier, smart rocks as field agents offer mission-critical information about the maximum depth of a scour hole developed around the bridge foundation – the key parameter that is used to assess foundation stability in engineering design and retrofit. Smart rocks have recently been deployed and tested at three bridge sites in California and Missouri. With multiple measurements, they can be located with an accuracy of 0.5 m. This level of performance, however, largely depends on the availability of a crane that extends the measurement station from the deck of a bridge to the proximity of a smart rock. The use of the crane often requires traffic closure and, more importantly, limits the number of measurement points and thus makes the detection of two or three smart rocks practically impossible. The location of a smart rock with embedded magnets is determined in four steps. First, the ambient magnetic field near a bridge pier where scour is expected to occur is measured with a 3-axis magnetometer. Second, a smart rock with a control mechanism of magnet rotation is deployed around the pier. Third, the total magnetic field including the effect of the magnets is measured with the magnetometer. Fourth and lastly, the location of the smart rock is evaluated by minimizing the difference between the measured and predicted magnetic fields. When a sufficient number of measurements are taken in a space around two or three sparsely distributed smart rocks, the rocks are likely located successfully in application. This project aims to develop a moving unmanned aerial vehicle (UAV) platform for the magnetic field measurement with and without smart rocks, and characterize the field performance of smart rocks so that the smart rock technology can be tested to its full potential for real time monitoring of bridge scour during significant flood events. The focus of this project will be to: (1) Design, build, and test a UAV with no more than 90-N payload of a 3-axis magnetometer, a lightweight onboard computer, and one or two batteries for at least 20 minute operation in field condition, (2) Establish the relation between the flight speed and the sampling rate of the magnetometer, and (3) Evaluate the localization accuracy of one, two, and three smart rocks.


Subject/Index Terms

Filing Info

  • Accession Number: 01646009
  • Record Type: Research project
  • Source Agency: Inspecting and Preserving Infrastructure through Robotic Exploration University Transportation Center
  • Contract Numbers: 69A3551747126
  • Files: UTC, RiP
  • Created Date: Sep 14 2017 11:02AM