Common underlying steering curves for motorcycles in steady turns

Abstract

We study the steady turn behaviours of some light motorcycle models on circular paths, using the commercial software package ADAMS-Motorcycle. Steering torque and steering angle are obtained for several path radii and a range of steady forward speeds. For path radii much greater than motorcycle wheelbase, and for all motorcycle parameters including tyre parameters held fixed, dimensional analysis can predict the asymptotic behaviour of steering torque and angle. In particular, steering torque is a function purely of lateral acceleration plus another such function divided by path radius. Of these, the first function is numerically determined, while the second is approximated by an analytically determined constant. Similarly, the steering angle is a function purely of lateral acceleration, plus another such function divided by path radius. Of these, the first is determined numerically while the second is determined analytically. Both predictions are verified through ADAMS simulations for various tyre and geometric parameters. In summary, steady circular motions of a given motorcycle with given tyre parameters can be approximately characterised by just one curve for steering torque and one for steering angle.

Keywords:

• motorcycle
• steering torque
• steering angle
• steady turn
• circular path

Acknowledgements

We thank TVS Motor Co., Ltd, for permission to publish this work, and Jim Papadopoulos and Amrit Sharma for commenting on an earlier draft. VMK thanks HB Pacejka for insights into tyre models. AC thanks David Limebeer for discussions of background issues, and Jim Papadopoulos for many insights, scattered among several documents on Andy Ruina's web page at Cornell University, http://ruina.tam.cornell.edu/research/topics/bicycle_mechanics/overview_papers_and_links.htm.

Notes

The physical interpretation of is indeed ‘small torque due to small lean without steer’.

Additional information

Notes on contributors

Anindya Chatterjee

Present address: Indian Institute of Technology, Kharagpur, India.