Cow locomotion energy harvester for powering IoT wearables

Abstract

Livestock wearables for precision livestock farming (PLF) or smart farming applications have gained in popularity in the recent years enabling farmers to monitor their livestock health or production parameters in almost real time. Most of the wearable devices incorporate a sensing device, like a motion sensor, a controller, and a wireless transmitter all of which are in most cases powered by a battery with a finite lifetime or in a best case scenario - a rechargeable battery. Although solar energy harvesting has been employed to increase device run-time, in certain cases and geographical latitudes this has not been sufficient. In this work we present a wearable electromagnetic kinetic energy harvesting (KEH) device with magnetic springs designed specifically for cattle. Based on measurements and analyzed free grazing locomotion of Finncattle at a dairy cattle farm in Tampere (FI) a KEH generator is designed, simulated using a custom built simulation tool based on finite element modelling and then manufactured employing rapid prototyping techniques. A smart power management circuit is chosen and incorporated in the device design alongside a voltage logger. The generator is first tested in a laboratory, both on a mechanical shaker and human subject while at a later phase the device is equipped on a cow’s foreleg by a pedometer strap. In a first field trial voltage generation is logged simultaneously with cow leg acceleration displaying correct coupling performance. In a second field trial a Bluetooth beacon transmitter is successfully powered by the cow’s intermittent stepping movement.