Sensing system for low cost condition monitoring of remote assets

摘要

Local councils, power and road agencies have tens of thousands of assets such as road signs, power poles, and public artworks. Asset management plans dictate that these assets need to be inspected periodically, for example once per year. In between inspections the assets are vulnerable to random events such as weather and adverse human interactions. Asset managers need to know when these events occur, as damage to these assets can impact public safety. Traditional instrumentation for this high volume, low asset value application has been too costly to install. This paper presents a low cost design and associated edge-processing strategy to enable low-power transmission of a vibration signal notifying of change in state of an asset. The design is demonstrated using a COTS (commercial off-the-shelf) microcontroller, MEMS (microelectromechanical system) accelerometer and a LoRa (Long Range spread spectrum modulation technique) module. We name our device RAMI (Remote Asset Management Indicator). The design draws less than 1 mA in normal operation, lasts over a year between battery changes, costs less than AU$100 (US$65) to construct and can transmit around 400 metres in an urban setting and up to 3 km in a rural setting. The open-source design and code are available for download.