Sistema para controle da frequência cardíaca através da velocidade de uma esteira ergométrica

Abstract

The objective of this study was to develop and analyze a system to control the heart rate (HR). The control system uses an reference model adaptive topology, with model reference with steady state gain unitary and time constant of 60 s, giving a settling time around 180 s. Were collected heart activity signals of 33 volunteers associated with speed signals during a moderate walking on a treadmill. The experimental protocol consisted of 1 min initial rest (stage 0), 5 min with target HR of 100 bpm (step 1), 5 min with target HR of 110 bpm (step 2) and 3 min of final rest (stage 3). The control system wa evaluated for its reference tracking performance, through the “Root Mean Square Error” (RMSE) of the error (e) between the measured HR and the desired HR during steps 1 and 2, and steady state performance through the mean (µ) and standard deviation (sd) of e during the last two minutes of steps 1 and 2. The tests presented RMSE = 5,17 ±1,11 bpm, µ = -1,31 ±2,15 bpm e sd = 3,38 ±0,92 bpm at stage 1, RMSE = 3,43 ±0,84 bpm, µ = -0,13 ±1,03 bpm e sd = 2,84 ±0,81 bpm at stage 2. The statistical analysis showed a significant difference between RMSE, µ and dp values of stages 1 and 2. These results indicate that, althought the control system was effective in both test stages, there is a tendency to improve performance on raising the target HR.