Modelling of longitudinal vehicle motion during low-speed driving
Publicerad
Författare
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The phenomenon of sudden jolts when riding in a vehicle is a well-known phenomenon
which is caused by friction forces between the ground, tyres, disc-brake
systems and suspensions. It is caused by two significant nonlinear singularities,
which arise from friction forces between the ground and the tyres as well as within
the disc-brake system. The jerk phenomenon occurs due to the frictional forces between
two surfaces when there is a change in the direction of their relative velocity.
In this thesis, some of the most common friction models will be investigated. Simulations
are performed to evaluate the limits and the performances of the different
models applied to a brake disc. Additionally, a novel tyre model based on the LuGre
friction model is implemented to address singularities at low speeds. A comparison
is made between this new model and the widely recognized Pacejka tyre model to
highlight the differences and the limits of each. Furthermore, a complete longitudinal
vehicle model featuring these tyre and brake models is developed. Different
complexities of the model are considered, ranging from a complete rigid vehicle
model to models featuring suspensions and compliances. This will allow us to gain
knowledge of where the jerk phenomenon arises. To validate the model, the mathematical
results are compared with experimental data obtained from actual vehicle
manoeuvres.