Design and evaluation of an adaptive dairy cow indoor positioning system : A study of the trade-off between position accuracy and energy consumption in mobile units with extreme battery life

Abstract: With growing farm sizes, increasing work load, and increasing social and legislative demands for loose housing, health monitoring of farm animals is playing a bigger role for farmers worldwide. A type of information that can be used to determine the health status of dairy cows is positional data. However, since dairy cows spend a lot of time indoors in protection from various weather conditions or to perform other activities, GPS solutions are not sufficient. Moreover, the devices that the dairy cows carry must have a long battery life in order to avoid frequent system maintenance. This thesis researches possible system solutions to enable indoor positioning of dairycows within loose housed freestall barns. The proposed system configuration is then optimized in terms of energy consumption, and the trade-off between dynamic energy consumption and position accuracy is investigated. Previous research has focused on one or the other, and the development of systems with extreme battery life has not been a priority. The proposed system uses a proprietary 433MHz radio frequency band to estimate the dairy cows’ positions, and accelerometer data to adaptively alter estimation frequency to minimize energy consumption. After the optimization process, the proposed system is shown to have a battery life of at least two years with an accuracy of approximately 7–8m and a precision of 11–12 mutilizing four anchor nodes in an experimental barn. The theorized correlation of the position accuracy and energy consumption could not be found. Keywords: indoor positioning, dairy cows, weighted non-linear least squares, energyconsumption, agriculture, system design, optimization, positioning accuracy, Sub GHzradio, battery life