Motorcycle control by variable geometry rear suspension (original) (raw)

On steering wobble oscillations of motorcycles

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2004

The paper is aimed at an improved understanding of steering wobble oscillations of motorcycles through simulation. The background to the problem is discussed first. Then, an existing mathematical model of a manoeuvring motorcycle and rider is extended to include a yaw freedom for the upper body of the rider. The rider upper body and arm structural parameters are chosen in the light of newly published results from the testing of human subjects in a driving simulator, with forced motion of the steering wheel by means of an electric motor. Results show that steering wobble oscillations grow more vigorously as their amplitude increases beyond a few degrees of steering and that the stabilizing influence of the rider's tensing his/her muscles in response to a growing wobble problem is small. The work supports the idea that any machine which has a very lightly damped wobble mode at some operating condition may be made unstable by an unusual set of initial conditions and that the natura...

Advances in the Modelling of Motorcycle Dynamics

Starting from an existing advanced motorcycle dynamics model, which allows simulation of reasonably general motions and stability, modal and response computations for small perturbations from any trim condition, improvements are described. These concern (a) tyre/road contact geometry, (b) tyre shear force and moment descriptions, as functions of load, slip and camber, (c) tyre relaxation properties, (d) a new analytic treatment of the monoshock rear suspension mechanism with sample results, (e) parameter values describing a contemporary high performance machine and rider, (f) steady-state equilibrium and power checking and (g) steering control. In particular, the " Magic Formula " motorcycle tyre model is utilised and complete sets of parameter values for contemporary tyres are derived by identification methods. The new model is used for steady turning, stability, design parameter sensitivity and response to road forcing calculations. The results show the predictions of the model to be in general agreement with observations of motorcycle behaviour from the field and they suggest that frame flexibility remains an important design and analysis area, despite improvements in frame designs over recent years. Motorcycle rider parameters have significant influences on the behaviour, with results consistent with a commonly held view, that lightweight riders are more likely to suffer oscillation problems than heavyweight ones.

Analysis of the Effect of Mass Parameters on Motorcycle Vibration and Stability

Energies, 2021

This paper presents a vibration analysis method and an example of its application to evaluate the influence of mass parameters on torsional vibration frequencies in the steering system of a motorcycle. The purpose of this paper is to analyze to what extent vibration frequencies can change during their daily operation. These changes are largely due to the ratio of vehicle weight to driver and load. The complex dynamics make it very difficult to conduct research using simple models. It is difficult to observe the influence of individual parameters because they are strongly interrelated. This paper provides a description of the vibration analysis method, and the results are presented in the form of Bode diagrams and tables. On this basis, it was found that the driver, deciding on the way of using the vehicle and introducing modifications in it, influences the resonant frequencies of the steering system. Typical exploitation factors, on the other hand, do not cause significant changes, ...

Cornering analysis of a motorcycle longitudinal traction control system

Advances in Engineering Research, NovaScience Publishers, Inc., 2019

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.