Lateral dynamics of a bicycle with passive rider model

This paper addresses the influence of a passive rider on the lateral dynamics of a Whipple-like bicycle model. In the original Whipple [8] model the rider is assumed to be rigidly connected to the rear frame of the bicycle and there are no hands on the handlebar. Contrary, in normal bicycling the arms of a rider are connected to the handlebar and the rider can use both steering and upper body rotations for control. From observations [2, 6] two distinct rider postures can be identified. The first posture is where the upper body leans forward with the arms stretched to the handlebar, and the upper body twists while steering. The second rider posture is an upright one where the upper body stays fixed with respect to the rear frame and where the arms, hinging at the shoulders and the elbows, exert the control force on the steering. Models can be made where neither posture adds any degrees of freedom to the original Whipple-like bicycle model. For both posture cases the open loop, or uncontrolled, dynamics of the bicycle-rider system is investigated and compared to the rigid rider model by examining the eigenvalues and eigenmotions in the 0 to 10 m/s forward speed range. It is shown that such a passive rider can dramatically change the eigenvalues and its structure with respect to those of the rigid rider model