Study on the Stability and Motion Control of a Unicycle : Part I : Dynamics of a Human Riding a Unicycle and Its Modeling by Link Mechanisms

摘要

In this paper, the dynamic characteristics of a human riding a unicycle are analyzed following observation. From the observation and analysis, we found that the rider's trunk, thighs and shanks form two closed-link loops, and this special mechanism plays an important role in the stability of the unicycle. Based on this idea, we developed a new model with two closed-link mechanisms and one turntable to enable a robot to emulate a human riding a unicycle. Considering the nonholonomic constraint between the wheel and ground, and using a recently developed general method to compute the multi-closed-link mechanisms' dynamic motion, we obtained the dynamic equations of motion for this new model. With these equations, the simulation is conducted under the proposed control method. The simulation result indicates that both the longitudinal and lateral stability of a unicycle ridden by a human can be satisfactorily emulated by this new model.