Modelling For Competitor Vehicle Analysis
2016
This thesis describes the development and evaluation of a competitor vehicle model for Volvo Cars
Corporation's moving base driving simulator. Vehicle simulations are important when aiming for
decreased development time within the vehicle industry. Simulations help the engineers to front-load
projects, thereby improving efficiency and product quality. To remain competitive it is essential to
know the industry's state of the art technology. One commonly used method is competitor analysis.
The thesis delivers a method of how to measure a competitor's vehicle in order to create a vehicle
model that can be tested objectively in VI-CarRealTime as well as subjectively in a driving simulator.
This gives the opportunity to save the competitor vehicle in a database and perform tests even if
the physical vehicle is no longer available. The thesis focuses mainly on capturing the lateral tyre
and steering characteristics of the competitor vehicle with the main priority to mimic the full vehicle
behaviour while minimising additional requirements needed compared to a standard measuring. It is
favourable to separate the different system in the full vehicle model in order to facilitate the vehicle
analysis on component level. Two methods are presented and carried out. One named Measurement
Based Method that requires measured tie-rod forces using strain gauge sensors on the tie-rods as
an additional measuring equipment. The second method named Estimation Based Method is using
the standard measuring equipment but instead requires a Brush Tyre Model to correlate lateral tyre
characteristics to aligning torque. The advantage of knowing the tie-rod forces is that tyres and
the steering system can be completely decoupled from each other which gives higher accuracy on
component level. The tyre model is optimised so that the simulated vehicle shows the same response
as the measured vehicle in a series of manoeuvres. The lateral tyre parameters are assumed to be
found when the vehicle model is achieving the same yaw rate and lateral acceleration as for the
physical vehicle in an identical manoeuvre. A steering algorithm is designed to imitate the behaviour
of vehicle's power steering system by estimating the relation between rack force and steering wheel
torque. The resulting steering algorithm is tuned to simulate the wanted steering system by adjusting
damping and friction parameters together with a base torque given by a velocity versus rack force
dependent look-up table. Objective evaluations show good correlation for low transient manoeuvres.
However, at higher transients the tuned models differentiated more from the measured data. The
Measured Based Method was thought to have higher accuracy when evaluating subjectively which
resulted in it to become the favourable method. Further work needs to be carried out on both the
steering system and the tyre optimisation in order to have an established method.
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