A Kalman Filter code was developed and implemented following the biophysical model proposed in the scientific paper “Estimation of core body temperature from skin temperature, heat flux, and heart rate using a Kalman filter” by Mark J. Buller et al. The algorithm estimates core body temperature and derives the PSI (Physiological Strain Index) using skin temperature and heart rate as input variables.
The primary task involved the fine-tuning of process (Q) and measurement (R) variances. Validation was conducted using the Prospie dataset, an open-access data collection from Loughborough University (study by James S. P. Tattersall et al.). This dataset enabled a rigorous comparison between the algorithm’s estimates and actual rectal temperature. Through iterative parameter calibration, the implementation achieved high accuracy, resulting in a root mean square error (RMSE) of 0.472 °C.