Robust control of heart rate for cycle ergometer exercise

Abstract

The objective was to assess the performance and robustness of a novel strategy for automatic control of heart rate (HR) during cycle ergometry. Control design used a linear plant model and direct shaping of the closed-loop input-sensitivity function to achieve an appropriate response to disturbances attributable to broad-spectrum heart rate variability (HRV). The controller was evaluated in 73 feedback control experiments involving 49 participants. Performance and stability robustness were analysed using a separately identified family of 73 plant models. The controller gave highly accurate and stable HR tracking performance with mean root-mean-square tracking error between 2.5 beats/min (bpm) and 3.1 bpm, and with low average control signal power. Although plant parameters varied over a very wide range, key closed-loop transfer functions remained invariant to plant uncertainty in important frequency bands, while infinite gain margins and large phase margins (> 62∘) were preserved across the whole plant model family. Highly accurate, stable and robust HR control can be achieved using LTI controllers of remarkably simple structure. The results highlight that HR control design must focus on disturbances caused by HRV. The input-sensitivity approach evaluated in this work provides a transparent method of addressing this challenge. Graphical AbstractHeart rate control using a cycle ergometer

Automatic heart rate clamp: A practical tool to control internal and external training loads during aerobic exercise

“…In addition to continuous exercise, the HR clamp approach has successfully been implemented to control intermittent exercise intensity (i.e., interval training sessions). For instance, through the use of an automatic HR clamp tool Hunt and Hurni (2019) had participants perform four intervals alternating between active (~140 bpm) and passive (~120 bpm) phases. The reported mean tracking error of ~3.1 bpm would suggest that HR can be closely controlled even when the target HR fluctuates during exercise.…”