Meeting Abstract
Many scientific studies and research projects require knowledge of the position of an animal on the Earth’s surface. When an animal is moving, frequent measurements of its position are required if one is to accurately record range and resource utilisation, contacts between animals and the nature of locomotor activity. Tracking collars fitted to wild animals are typically designed to operate for months or years to avoid the need for frequent battery replacement. This tight power budget restricts the number of GPS position measurements that can be made, giving only a limited picture of an animal’s movement, speed and locomotor repertoire. Here we show that this issue can be resolved by using low rate GPS measurements combined with a dead-reckoning approach, utilising measurements from MEMS accelerometers and magnetometers, which operate at much lower power than GPS modules. Dead-reckoning was employed to create a fine scale reconstruction of the animal’s path by calculating speed estimates from the accelerometers and heading estimates from the magnetometers. As errors in the dead-reckoned path propagate with time and speed, a drift correction solution, which uses intermittent GPS fixes, was used to keep the reconstruction within acceptable bounds of accuracy. A custom-built wildlife collar was deployed on 10 freely exercising domestic dogs, collecting a total of 45 hours of data. We show that the dead-reckoning method can be used to continuously track legged locomotion between 5 minute GPS fixes with an RMS error of less than 3.8% of path length between GPS fixes. The power cost of this is less than 2.6% of that required to run a GPS module continually.
