Despite decades of study, scientists and researchers still don’t have much information on the habits and migration patterns of polar bears. As climate change has progressed, behavioural and migration patterns of polar bears have evolved and made it increasingly difficult to reliably track their locations. Implementing a feasible tracking solution for polar bears is critical for gathering data around their behaviour – especially as more polar bears are traveling further and further south, increasing their contact with humans and, unfortunately, having to be killed as a result.
World Wildlife Fund partnered with design and innovation company IDEO at the International Conference on Bear Research and Management in 2016 to host a workshop that included scientists, polar bear experts, zoologists, device manufacturers and members from Inuit communities to discuss the current state of bear tracking, and how future tracking devices should look and function. Some conclusions around the practical issues for bear tracking were that collars don’t work for male bears, as their necks are larger than their heads, and a release mechanism is vital to a tracking device’s design so it wouldn’t need to be permanently attached to the bear.
Beyond the release mechanism, there stood a critical challenge around the robustness of the antenna for satellite telemetry-based trackers. For tracking wildlife–such as birds and their migration–the most common system is Argos Satellite Telemetry. The antennas for Argos devices are typically a thin wire, up to 18cm in length. For a polar bear, however, the cold arctic climate combined with aggressive behaviour typically results in these antennas breaking.
From the workshop with WWF and IDEO, a framework of requirements was created for what an ideal polar bear proof tracking device would consist of; something that could be attached to a bear’s ear, connect with a satellite network, safely transmit data regarding location and activity to researchers, and then automatically release after a given time period.
IDEO contacted MistyWest for the electronics design of the desired tracking device, and our IoT engineering team proposed a design architecture based on the Iridium Satellite Communications; a network offering the best global coverage, with worldwide L-band voice and data communications through handheld devices. Already equipped with experience working with Iridium, our team began the early stages of development for the tracking device.
An Iridium solution solved many of the issues that were presented at the conference’s workshop; namely, it allowed for a straightforward antenna design which could be packaged in a robust manner. However, L-band transmission requires a fair amount of power to reach the satellite network. There are very high current peaks during transmission, which require a hefty battery to sustain those peaks. Once the design was underway, we determined the Iridium module’s battery requirements would push the weight of the tracking device to nearly twice the target weight set out in the conference’s workshop. Therefore, it was time to look for another solution.
After more research and understanding around these weight restrictions, a chip-down, lower power solution using the Argos System was introduced, which would reduce the device’s battery requirements. We were able to develop a precise power management control system to optimize transmission times according to the Argos satellite pass schedule, enabling a battery life of up to 6 months, while still keeping the device light enough for the polar bear’s ear.
Now, all we had to do was design an antenna which could hit the Argos network and stand up to a 1,500lb tank covered in fur.
MistyWest’s systems engineering team set out to design and tune a custom 400Mhz internal antenna, which could be potted to avoid the breakage issues common to Argos tracking devices, while our electrical team designed a tiny rigid flex PCB for the electronics that can conform to the shape of the polar bear’s ear.
After 3 revisions to the antenna, our custom design is able to reliably communicate with the Argos satellite network – making MistyWest one of the first engineering teams to produce a compact internal antenna Argos-based tracking device.
The polar bear tracker MistyWest ultimately developed for the World Wildlife Fund can have its transmission times set and its location status monitored via Doppler geolocation. The device collects time-stamped actigraphy, temperature and pressure data thanks to a Bluetooth Low Energy enabled MCU, which also provides a wireless interface for local researchers who can set deployment parameters, update a device’s configuration, and even update the device’s firmware.
The device includes the time-based release mechanism outlined in the requirements, and an enclosure that is fully waterproof and able to withstand some of the world’s harshest weather conditions.
Currently, we are in the final bench testing stages and preparing for delivery to WWF and the US Fish and Wildlife Service. Field testing of the device is planned for the second half of 2021.