Analytical Methods in Vehicle Dynamics
Yaw stability of a passenger vehicle with respect to road disturbances
Project group
Peter Folkow, Associate Professor, Division of Dynamics
Mathias Lidberg, Associate Professor, Division of Vehicle Engineering and Autonomous
Systems
Background
The research group in vehicle dynamics is studying active safety systems to improve safety and
stability for passenger and heavy vehicles. Much of the development in this area concerns control
technology with new actuator systems such as active steering and differentials. However, there
are still a need for the development of the automotive chassis and tire. There are many interesting
problems within modern vehicle dynamics that are directly related to advanced analytical
mechanics. Consequently, there are needs to combine knowledge from both vehicle dynamics
and analytical mechanics [3]. In this project, the latter field is covered by the Division of
Dynamics which has competence within rigid body mechanics, using both analytical and
numerical methods.
Project Proposal
Tire characteristics are of crucial importance for the dynamic behavior of the road vehicle. It is
well known that the steady state slope of the tire side force vs slip angle near the origin is the
determining factor for basic linear handling and stability. The stability of the motion at large
lateral acceleration is in a similar way determined by the local slope of the same tire
characteristic and other factors such as wheel camber angle [4]. Recently, tire models capturing
the influence of tire pressure and wheel camber have been developed [1]. However, very little is
known about the influence of these tire properties on the stability of road vehicles. It is therefore
proposed to study the yaw stability of a passenger vehicle with respect to road disturbances
including more detailed tire characteristics [2]. It is expected that the stability analysis is
challenging and requires approaches beyond linear stability theory e.g. Lyapunov stability theory.
Implementation
The two students will work together in the same office at Chalmers Johanneberg. All four (the two
students and the two supervisors) will have one meeting every second week. At least one of the
supervisors will meet the students once a week.
Project plan:
Introduction (1 week)
Literature Review ( 1 week)
Modeling and Stability Analysis (4 - 6 weeks)
Simulation Study (4 - 6 weeks)
Thesis Writing (4 weeks)
Presentation (2 weeks)
Anticipated research results and synergy effects
This project will be carried out as a cooperation between the Divisions of Dynamics and Vehicle
engineering and Autonomous systems.
It is anticipated that this research will result in new insight in the vehicle dynamics field, based
on rigorous treatment of the tire-road interaction and its influence on vehicle stability. This kind
of projects is quite rare, as much research within vehicle engineering is based on simplified
assumptions that sometimes are questionable for detailed analysis. It is likely that the result of the
thesis can be published at least at a scientific conference.
The proposed work is important for the vehicle dynamics research projects performed at
Chalmers. These projects involve similar aspects to the work proposed but does not allow for the
rigorous treatment aimed for here. The results are also expected to be possible to apply by the
vehicle industry e.g. Volvo, SAAB in their development process. This will hopefully increase the
chances of attracting industry funding for further activities in this field.
References
1. I. J.M. Besselink, A. J.C. Schmeitz, H. B. Pacejka, An improved Magic Formula/Swift tyre
model that can handle inflation pressure change, Vehicle System Dynamics 2010.
2. W.Liang, J.Medanic, R.Ruhl, Analytical dynamic tire model,Vehicle System Dynamics, 2008.
3. B. Andersson, P. Gillberg, High Speed Braking Stability, MSc Thesis, Chalmers University of
Technology 2013, http://studentarbeten.chalmers.se/publication/179619-high-speed-brakingstability.
4. CamberTire, http://www.cambertire.com/