Basic study on upright stability of a small wheel bicycle with steer-by-wire system

From the view point of the environmental protection and convenience for transportation, a bicycle is one of the effective forms of the personal mobility vehicles. It is known that a small wheel bicycle running at low speed has less upright stability. In this study, Steer-by-Wire system is used to steer and stabilize a small wheel bicycle. In a bicycle with Steer-by-wire system, the mechanical connection between handlebar and steer-assembly is replaced by electronic connection with actuators, sensors and a controller. The system can enhance the upright stability of a bicycle by a control system. This study aims to enhance the upright stability of a small wheel bicycle at low speed. Firstly, we conducted the eigenvalue analysis to evaluate the upright stability of a bicycle and examined the difference of the stability between a bicycle with normal wheel and a small wheel one. Secondly, we designed the mechanism of Steer-by-Wire system and examined the effectiveness of Steer-by-Wire system in a small wheel bicycle. Finally, we investigated the behavior of a small wheel bicycle with Steer-by-Wire system when the system is subjected to disturbance torque. As a result, we found that Steer-by-Wire system could enhance the upright stability of a small wheel bicycle at a low speed.