Piepser 2.0: A Self-Sustaining Smartwatch to Maximize the Paragliders Flytime

• Published in: IEEE transactions on instrumentation and measurement Vol. 69; no. 4; pp. 1445 - 1454
• Main Authors: Baumann, Nicolas, Ganz, Michael, Magno, Michele
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.04.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Audio data; Barometric sensors; Batteries; Biomedical monitoring; Data handling; Electric inductors; Electric power supplies to apparatus; Energy harvesting; Form factors; Intelligent sensors; Lithium; Lithium-ion batteries; Low Power; low-power sensing; low-power wearables; Microcontrollers; Multi-source energy harvesting; On-board processing; Paragliders; Power consumption; Power management; Precision flight; precision flight instruments; Rechargeable batteries; Systems architecture; Variometers; Vertical velocity; Wearable computers; Wearable sensors; Wearable technology; Wireless communication; Worst case scenario; Wrist
• ISSN: 0018-9456; 1557-9662; 1557-9662
• DOI: 10.1109/TIM.2019.2957865

The main motivation of paraglider pilots is to stay in the air for as long as possible. Therefore, paraglider pilots are always searching for thermal upwind that allow them to gain altitude. These thermal lifts are difficult to detect. Therefore, sensors and devices that indicate the vertical speed (so-called variometers) are widely used among paraglider pilots. This article presents the design and the implementation of an ultralow-power, self-sustaining, high-precision, wrist-worn variometer with a minimal form factor but infinite lifetime, which can visually and acoustically indicate the vertical velocity. This article demonstrates the benefits of combining multisource energy harvesting (EH) for wearable devices with low power design, exploiting a novel near-threshold ARM Cortex-M4F microcontroller, the Ambiq Apollo2, for the onboard processing. The experimental results show a power consumption of only <inline-formula> <tex-math notation="LaTeX">17.12~\mu \text{W} </tex-math></inline-formula> in sleep mode and <inline-formula> <tex-math notation="LaTeX">1937.21~\mu \text{W} </tex-math></inline-formula> in the worst case scenario when processing the data and outputting an audio feedback. Measurements confirmed that combining both thermal and solar EH makes the designed electronics self-sustaining. Without EH, the system will be operational for up to 372 h in always-on mode (worst case scenario) supplied by a 200-mAh lithium-ion battery.