It is crucial to understand the mechanism to improve the initial examination accuracy of the dynamic characteristic for the efficient development of motorcycles. In this paper, we focus on “leaning” which is one of the dynamic characteristics. While the rider operations and the physical characteristics have an impact on the motorcycle dynamics, since we focus on the vehicle characteristics themselves, bicycles are used for making an unmanned running state.
At first, several specifications with different "leaning" characteristics are prepared based on the riding feel of the experimental rider. In experiment, it is observed that the roll angle and steering angle synchronize or do not synchronize depending on the differences in mass distribution. Therefore, the hypothesis is established that the “leaning” is strongly influenced by the phase lag between roll and steering angles. In addition to that, the lag, at least, changes with the mass distribution.
Next, based on this hypothesis, theoretical considerations are made using the well-known Sharp model. Among the eigenvalues of the Sharp model, attention is paid to the weave root and capsize root as eigenvalues that might correspond to "leaning". The contribution of vehicle specifications to these eigenvectors is then examined. As a result, when the moment of inertia of the rear frame is changed, the imaginary part of the relationship between the roll and steering angles in the weave root significantly changed. Since the imaginary part is related to the phase lag, this result indicates that the phase lag between the steering angle and roll angle changes. On the other hand, in the capsize root, no significant changes occurred in all eigenvectors. Therefore, under the set assumptions, it is considered that the mechanism of "leaning" is the manifestation of the weave.
co-authors:
Yoshihiro NAKAGAWA (Honda Motor Co., Ltd)
Yoshitaka TEZUKA (Honda Motor Co., Ltd)
Hiroki YAMASHITA (Honda Motor Co., Ltd)
Shunichi MIYAGISHI (Honda Motor Co., Ltd)