Kinematic Loggers-Development of Rugged Sensors and Recovery Systems for Field Measurements of Stone Rolling Dynamics and Impact Accelerations during Floods.

Hamish Biggs,Graeme Smart,Andrew Starr,Julian Sykes,Steve De Lima,Murray Hicks,Arman Haddadchi,Brendon Smith

doi:10.3390/s22031013

Hamish Biggs, Graeme Smart + Show 6 more

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https://doi.org/10.3390/s22031013

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Abstract

Discrete particle dynamics is one of the least understood aspects of river bedload transport, but in situ measurement of stone movement during floods poses a significant technical challenge. A promising approach to address this knowledge gap is to use sensors embedded within stones. Sensors must be waterproof and recoverable after being transported downstream and potentially buried by other sediment. To address this challenge rugged sensors (Kinematic Loggers) were developed for deployment inside stones (ranging in size from cobbles to boulders) during floods. The sensors feature a 9-axis inertial measurement unit, 3-axis high-g accelerometer, 128 MB flash memory, and a 433 MHz LoRa radio transmission module for sensor recovery. The sensors are enclosed in rugged waterproof housings for deployment in extreme conditions (i.e., bedload transport during floods). Novel relay units and drone-based recovery systems were also developed for finding the sensors after field deployments. Firmware to control the sensors and relay units was developed, as well as software for configuring the sensors and an android application for communicating with the sensors via the LoRa radio transmission module. This paper covers the technical development of the sensors, mounting them inside stones, and field recovery tests. Although designed for measurement of coarse bedload transport and particle dynamics during floods, the sensors are equally applicable for deployment in other harsh environments, such as to study landslide and rockfall dynamics.

Highlights

Publisher’s Note: MDPI stays neutralTectonic activity, weathering, erosion, and sediment transport are key processes that shape the landscapes of the Earth [1]
Over the last two centuries many sediment transport formulae have been developed [4]. They are primarily empirical and often have poor predictive performance when extended to conditions outside those to which they were ‘fit’ [5,6]. This is true for bedload transport formulae, where there is a scarcity of reliable field data to test them [5], as well as knowledge gaps around the dynamics of individual particles during bedload transport [5,7]
This paper aims to address these challenges, through the development of rugged sensor/logger systems featuring a 9-axis inertial measurement unit for stone angular velocities, accelerations, and orientation, with a 3-axis high-g accelerometer to record shocks and impact accelerations

Summary

Introduction

Publisher’s Note: MDPI stays neutralTectonic activity, weathering, erosion, and sediment transport are key processes that shape the landscapes of the Earth [1]. Over the last two centuries many sediment transport formulae have been developed [4] They are primarily empirical and often have poor predictive performance when extended to conditions outside those to which they were ‘fit’ [5,6]. This is true for bedload transport formulae, where there is a scarcity of reliable field data to test them [5], as well as knowledge gaps around the dynamics of individual particles ( rolling dynamics) during bedload transport [5,7]. These problems are hardly surprising considering the harsh conditions at the bottom of a flooded river when gravel, cobbles, and boulders smash, roll, and grind with regard to jurisdictional claims in published maps and institutional affiliations

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