IT vendorResearch and development division
Challenge of Powering IoT Devices to Monitor Ageing InfrastructureEngineers encountered unexpected hurdles when attempting to transmit monitoring data in punishing environments
With buildings, bridges, waterfront retaining walls and other infrastructure built during Japan’s period of rapid economic growth ageing rapidly*, the establishment of systems for ensuring the safety of these infrastructure is now a matter of urgency. The situation has caused IT vendors to accelerate their efforts to develop predictive maintenance systems that incorporate IoT technology.
The vendor described in this case study was working on a predictive maintenance system that incorporated independently-developed sensing technology. While the development process began smoothly, the vendor subsequently encountered hurdles.
*The percentage of Japan’s 700,000 bridges that is over 50 years old is growing rapidly, and is projected to reach 63% by March 2033.
(Source: Shakai Shihonno Kōreikano Genjōto Shōrai [Aging of Social Capital Today and in the Future]─Ministry of Land, Infrastructure, Transport and Tourism)
Reliable Power Supply is vital while Wiring Not Always Possible
The vendor was developing a predictive maintenance system that incorporated two functions: a sensing function to perform monitoring and a communications function to transmit the data collected. While the vendor envisaged powering these functions with electricity, many of the locations requiring monitoring were bridge piles, or locations to which it was otherwise difficult to run wires. The vendor then experimented with a battery-based system, but this was problematic too, because primary batteries needed to be able to be replaced easily and periodically. Thus, the vendor’s research and development division encountered a challenge in the form of finding a reliable power supply.
Rechargeable Options were all too Large and Fragile
A few days later, one of the researchers who was working on the problem proposed using rechargeable batteries, and charging them with electricity supplied by photo voltaic cells, vibration-powered generators, or other energy harvesting devices. The team set about building a prototype straight away, but all of the rechargeable batteries they tested had poor environmental resilience and degraded rapidly.
Furthermore, the system would be installed in locations that could reach over 60°C in direct sunlight in summer, as well as regions that experience extreme winters where temperatures can drop as low as -20 or -30°C. Because of these considerations, the team reached to a conclusion that the batteries to be unsuitable for an outdoor predictive maintenance system. Furthermore, the batteries provided too little current to simultaneously power both monitoring and communication functions, therefore would need to be recharged frequently. The team also found that all of the rechargeable batteries tested were very large, causing their system to have a larger footprint than planned. These power supply snags caused the development process to grind to a halt, and the engineers were at a loss to know what to do.
The team considered primary batteries to power their predictive maintenance system in locations to which it was difficult to run mains power, but there was a limit to the regularity with which batteries could be replaced.
The team also tried conventional rechargeable batteries, but all the batteries tested had poor environmental resilience and ran down quickly. These batteries also had a low power output and did not conform to the vendor’s size specification.