Cornering analysis of a motorcycle longitudinal traction control system

The development of Active Safety System technologies is an emerging topic in regard to Powered Two-Wheelers (PTW’s). In the wake of new technologies available, many governments are legislating in vehicle safety, and this is prompting the manufacturers of PTWs to innovate their active safety devices.The main issue in designing stability control systems for PTW’s lays in the different and complex driving dynamics in comparison to four-wheeled vehicles.The present work analyses the effects of a longitudinal Traction Control System on the dynamics of a PTW in cornering conditions, i.e when the lateral dynamics arise. Following a model-based design approach, the behaviour of a PTW in cornering can be described with sufficient accuracy if both the longitudinal and the lateral dynamics are considered. Further improvements concerning the analytical treatment of the slippages allow the model to simulate falls. The motorcycle’s model used in this work represents one of the first attempts proposed in literature to analytically address the analysis and prevention of two-wheeled vehicle falls, whose complex dynamics normally requires the use of multibody software. A model-based control design for PTW allows the investigation of the performance of a Traction Control System not only when the vehicle travels in a straight line, but also in cornering and in presence of adverse road conditions, i.e. when the sideslip arises due to slippery road conditions. In straight line motion there is only longitudinal dynamics. In cornering, the lateral dynamics is also exhibited and it is coupled with the longitudinal one. Until now, in literature, the Traction Control Systems have been addressed by considering only the longitudinal slip dynamics. Although in absence of lateral slippage a longitudinal controller can reduce the oversteer phenomenon and improve the two-wheeled vehicle’s behaviour in cornering, this does not happen anymore in adverse road conditions. The driving torque that guarantees the longitudinal traction can be computed by a model-based control system taking into account the non-linearities of the friction forces acting on the tyres. The controller has been tested in a simulation environment, based on the PTW’s analytical model proposed by the authors.