Powertrain modeling for realtime simulation
The goal of this thesis was to develop a powertrain model of a vehicle
and parametrize it using non-invasive sensors. The non-invasive
sensors available were chassis dynamome- ter, the pedal robot and the
vehicle’s on-board diagnostics which was accessed using a scan
tool. Non-invasive sensors were used so that the vehicle to model can
easily be changed. A parametrization methodology to parametrize the
model for a new vehicle was also developed to facilitate the change of
vehicle. The powertrain model is for cars with a combustion engine and
a manual gearbox.
The engine model consist of two static maps, a pedal map and an engine
map. The pedal map is created using the fact that a constant pedal
position and engine speed gives a constant throttle position. The
engine map is created in similar manner using that a constant throttle
position and engine speed gives a constant engine torque. The engine
model also uses a first order lag element to model the time delay from
a change in pedal position to a change in wheel torque. The driveline
model is a rigid driveline model that assumes that the clutch,
driveshaft and propeller shaft are stiff.
The developed parametrization methodology contains information on how
to estimate the parameters of the model which are gear ratios, engine
and driveline inertias, engine and driveline losses, engine and pedal
maps and the time constant for the time delay. The powertrain model
was validated component wise, as standalone and integrated into the
vehicle model against data gathered with the help of the chassis
dynamometer. For the standalone and integrated validation the gathered
data were for different driving cases, such as up and down
gear-shifting, engine braking and skipping gears. The standalone
validation showed that the model performed well for the presented
driving cases and the results had good data fit for 3rd gear and
higher. However not for 1st and 2nd gear due to problems in the pedal
map. The pedal map was constructed on the assumption that the same
pedal position for all gears gives the same throttle position, which
was not always the case. This caused problems in some areas of the
engine and pedal maps however in the validation of the maps it was
shown that the maps for the most part gave good results.
Simon Lind
2014
Informationsansvarig: webmaster
Senast uppdaterad: 2021-11-10
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