Abstract
This work shows numerous experimental and simulation results regarding the stability of a threewheeled vehicle. Some vibration modes concerning three-wheeled vehicles can become unstable for a given vehicle speed. In particular, the wobble mode involves mostly the front frame while the weave mode involves mostly roll and yaw oscillations of the rear frame. This paper mainly focuses on the wobble mode, which was identified as the most influential vibration mode impacting vehicle handling, through experiments on the road using the three-wheeled passenger vehicle.
A large number of parameters such as caster trail, steering damping coefficient, front frame inertia about steering axis, front tire characteristics and chassis stiffness influence the wobble vibration mode. This work mainly focused on steering damping coefficient and caster trail, and its effect on wobbling stability. The effect of steering damping coefficient and trail on wobble mode was studied with multi-body dynamic simulation using commercial dynamic software and experimentally. A three-wheeled vehicle was instrumented with appropriate sensors for measuring steering angle, steering torque and vehicle speed. The experimental results were well correlated with simulation results. Based on the test results, the steering damping coefficient and trail were optimized for improving wobbling stability.