Reset control to suppress the instability of cardiac-locomotor synchronization at running

Abstract

It is known that a phenomenon in which a cardiac rhythm synchronizes with a locomotor rhythm occurs during running. At this synchronization, the cardiac rhythm rate increases in proportion to the locomotor rhythm intensity, and when it approaches the limit locomotor rhythm intensity, an unstable phenomenon of the cardiac rhythm increases becomes sometimes observed. This instability of the cardiac rhythm causes lower exercise efficiency, so it is necessary to keep the stable cardiac rhythm up to the faster locomotor rhythm as far as possible. Therefore, we obtain a frequency domain model with a locomotor rhythm added to the Van der Pol equation that expresses the cardiac rhythm, and propose a reset controller to suppress the instability of the cardiac rhythm by using the descriptive function method for this model.