Reliable Energy Sources as a Foundation for Reliable Intermittent Systems Dhananjay Jagtap Pat Pannuto
[email protected] [email protected] University of California, San Diego University of California, San Diego ABSTRACT be accessible to change batteries [11]. This is the case when de- This paper defines architectural and operational principles for sim- ploying sensor networks for structural or condition monitoring ple and reliable energy harvesting devices that can be used in service in industrial environments [38] or for environmental monitoring of high-level applications. For many maintenance and monitoring applications where there is no built infrastructure. This is part of tasks, we propose that it is more valuable to have reliable, trusted what makes energy harvesting designs so exciting: they present affirmations that nothing has changed than it is to know theexact the potential for set-it-and-forget it systems that can go anywhere moment that something has failed. This presents an opportunity for and last forever [16]. a new class of highly reliable, but not necessarily timely, intermit- What often makes energy harvesting designs challenging, how- tent devices. These are devices that are capable of sending messages ever, is that energy sources are unreliable, unpredictable, or un- at reasonable, fixed intervals (e.g. once an hour or once a day). They controllable. Early designs simply ran whenever they could for as cannot activate more often, but they also promise not to activate long as they could [10, 31, 35]. However, this wholly uncontrolled less often. To establish this reliability, we look to opportunities for intermittency made it difficult for device and system designers energy scavenging that are often ignored as their instantaneous to build applications.