The dynamics of a three-wheeled narrow-track tilting vehicle

Three-wheeled tilting vehicles have many potential advantages. They combine the comfort and safety of a car with the fuel economy, size and manoeuvrability of a motorcycle. One major challenge is to fully understand and account for the unusual dynamics of this type of vehicle. This paper sets out the equations of motion for a vehicle with single front and twin rear wheels and compares them with those of a car and a motorcycle. The mathematical model shows that it is necessary to introduce a tilt-dependent rear wheel steer term to obtain balanced handling characteristics. A vehicle with a hydraulically actuated tilting system is considered as a case study. As the tilt actuators act against the non-tilting engine module, this has significant effects on the cornering dynamics. Finally, the difference between the lateral acceleration and the hydraulic response time is shown to be a key issue.