Sliding Mode Control for Heart Rate Regulation of Electric Bicycle Riders

In this paper a new controller for electric bicycles is proposed to maintain a desired heart rate level and improve the riding experience of cyclists. The controller achieves this by adequately adjusting the motor assistance without affecting the cycling velocity. First, a human heart rate model is fitted to experimental data to model the heart rate response of cyclists during different exercises. Then, a sliding mode controller is designed to keep the human heart rate at a predefined level. Furthermore, a feedforward controller is introduced into the system to improve both the tracking performance and riding experience. The feedforward controller consists of an inverse human heart rate response model, which estimates the necessary rider torque for a desired heart rate level. The controller is implemented with a commercial electric bicycle. Simulation and experimental results are presented to assess the validity of the controller. Whereas the sliding mode controller itself achieves good tracking performance, the sliding mode control combined with the feedforward control additionally reduces the maximal exerted rider torque and improves the riding experience.