Researchers Silvano Cortesi, Lukas Schulthess, Davide Plozza, Christian Vogt, and Michele Magno from the Swiss Federal Institute of Technology in Zurich have developed a novel indoor localization system called Eco-WakeLoc, designed to address the energy efficiency and responsiveness trade-off in real-time locating systems (RTLS). Their work, published in the journal IEEE Transactions on Mobile Computing, presents a solution that combines ultra-low power wake-up radios (WuRs) with solar energy harvesting to achieve centimeter-level accuracy while maintaining energy neutrality.
Eco-WakeLoc is designed to overcome the limitations of traditional RTLS, which either require continuously powered infrastructure, limiting their scalability, or are constrained by their responsiveness. The system activates anchor nodes only when necessary, eliminating constant energy consumption and achieving centimeter-level positioning accuracy. This approach is particularly relevant for emerging use cases such as mobile robots operating in GPS-denied environments, where precise and efficient localization is crucial.
One of the key innovations of Eco-WakeLoc is its cooperative localization mechanism. Active tags initiate ranging exchanges (trilateration), while passive tags opportunistically reuse these messages for time difference of arrival (TDOA) positioning. This cooperative approach reduces coordination overhead and improves scalability, making the system more adaptable to various indoor environments.
To ensure long-term energy neutrality, Eco-WakeLoc employs an additive-increase/multiplicative-decrease (AIMD)-based energy-aware scheduler. This scheduler adapts localization rates according to the harvested energy, maximizing the overall performance of the sensor network. The measured energy consumption is remarkably low, with active tags consuming 3.22mJ per localization, passive tags consuming 951uJ, and anchors consuming 353uJ. Real-world deployment on a quadruped robot with nine anchors confirmed the system’s practical feasibility, achieving an average accuracy of 43cm in dynamic indoor environments.
Year-long simulations demonstrated that tags can achieve an average of 2031 localizations per day while retaining over 7% battery capacity after one year. This sustained energy-neutral operation highlights the potential of Eco-WakeLoc for long-term, large-scale indoor localization applications.
For the energy sector, Eco-WakeLoc’s technology could be particularly useful in monitoring and managing energy assets in indoor or GPS-denied environments, such as large industrial facilities, warehouses, or underground infrastructure. The system’s energy neutrality and high accuracy make it a promising solution for applications requiring precise tracking and localization without the need for continuous infrastructure operation.
This article is based on research available at arXiv.