go.warwick.ac.uk/lib-publications启航考研班怎么样
Original citation:
Bin Raja Ahsan Shah, Raja Mazuir, Cheng, Caizhen, Jones, R. Peter and Pawar, Jasjit (2011) Modelling of 4WD vehicle driveability during tip-in/tip-out events. In: 22nd
International Symposium on Dynamics of Vehicle on Road and Tracks (IAVSD),
Manchester, UK, 14-19 Aug 2011. Published in: IAVSD 2011 : 22nd International
Symposium on Dynamics of Vehicles on Roads and Tracks : 14-19 August 2011
go on and go(No.0085). pp. 1-6.
Permanent WRAP url:
wrap.warwick.ac.uk/51652
Copyright and reu:
The Warwick Rearch Archive Portal (WRAP) makes the work of rearchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper prented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.
Copies of full items can be ud for personal rearch or study, educational, or not-for-profit purpos without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way.
刘伟楠A note on versions:
The version prented here may differ from the published version or, version of record, if you wish to cite this item you are advid to consult the publisher’s version . Plea e the ‘permanent WRAP url’ above for details on accessing the published version and note that access may require a subscription.
For more information, plea contact the WRAP Team at: wrap@warwick.ac.uk
MODELLING OF4WD VEHICLE DRIVEABILITY DURING TIP-
IN/TIP-OUT EVENTS
Raja Mazuir Raja Ahsan Shah1,Caizhen Cheng1,R.Peter Jones1,Jasjit Pawar2callcenter
1School of Engineering,University of Warwick,Coventry,United Kingdom
controversial
2Jaguar Land Rover,United Kingdom
e-mail:esriau@warwick.ac.uk
Abstract
This paper describes a modelling method to investigate the dynamic behaviour of4WD vehicle under a vere driving condition,where the driver applies a rapid tip-in on the accelerator pedal in2nd gear to achieve maximum engine torque.This is followed by a tip-out event by releasing the accelerator quickly.
The Tip-In/Tip-Out events are one of important elements to asss the vehicle driveability.During the test events,the vehicle is expected to generate low frequency vibration between2Hz and10Hz and gives discomfort feelings induced by resonance effects on nsitive human organs.The aim of this paper is to develop a4WD vehicle model in a modern object-oriented multi-body simulation tool and study its driveability.
1.INTRODUCTION
Not many evidences have been en on the rearch carried out to examine the eminence of the vibration respon in4WD vehicle system predominantly in the Tip-In/Tip-Out events.The basic test method is to study the interaction between the driver and vehicle in terms of driveability at low speed events.The results can be analyd to identify the root cau of the low frequency respons.From the past investigation[1],the exposure of low frequencies to the driver leads to a n of discomfort induced by resonance effects on different human organs such as upper torso,lower abdomen and shoulders.
The previous effort[2]that influenced this work has resulted in the development of a single Torsional Model, a single Fore-Aft Model using the ADAMS modelling environment to study the above behaviours.Both models have been correlated with the ADAMS full nonlinear model as a reference model and the vehicle testing data.The development of the single models was due to the long computation time of the ADAMS full nonlinear model. Furthermore,it was not possible to u the full nonlinear model for a real time application due to the complexity of its architecture,which consisted of more than550Degree of Freedom(DoF).One aim of the work was to accelerate the process of tuning the properties of the system components to improve the vehicle driveability.However,the two models were not connected to reprent the actual physical behavior of the vehicle system due t
o the lack of tyre model.Hence,it did not demonstrate the actual interaction between the two sub systems.In addition,there were limitations to the development of control strategies in real time using ADAMS.This is due to long computation time and the ability to host the model in a real time platform.
Considering the above factors,Dymola modelling platform[3]has been lected to develop the model of vehicle system bad on the open-source Modelica language.For this rearch,the vehicle model was constructed from standard and extended Modelica libraries by tting up the vehicle parameters.The model was also integrated in a MATLAB/Simulink environment and implemented in the real time platform,which allows the development of control strategies.
From this experimental result,the vehicle model characteristics at low frequencies have been derived to give the prediction of the vehicle driveability behavior.In the remaining of this paper,the modelling methods and modelling details are prented in the next topics,which explained the results of simulation in Dymola,real time simulation and conclusion of this rearch.
2.MODELLING
The architecture of the vehicle model was bad on a4x4platform with2.2L Diel engine mounted in East-West orientation.It consists of all drive-train subsystems and the chassis components acting on
longitudinal direction.
The physical characteristics of the components were reprented by combining the torsional and fore-aft elements with the correct mechanical properties.The interaction of the drive-train and chassis systems was captured by a nonlinear tyre model in longitudinal direction,which was derived from simulation data to give a true behavior of the tractive force on different road surfaces.
In order to build the complete reduced order architecture of the vehicle system,the Dymola single models were correlated with ADAMS single models by using the same inputs,which were extracted from vehicle measurement.The models then were coupled after the results have satisfied the specific output ank speed and at acceleration.This Coupled model then has been correlated with the ADAMS full nonlinear model.Figure 1shows the architecture of the single Torsional Model and single Fore-Aft Model.
romeo and juliette
a)Torsional Model b)Fore-Aft Model
Figure 1:4WD Single Dymola Vehicle System Architecture
2.1Single Torsional Model
With the adopted approach,the torsional system of engine and drive subsystem components had been simulated to determine the transient respon when subjected to the torque signal from the dri
ver.The number of DoF has been reduced to less than 20to reduce the computation time [2,4].All sub systems were linear except the Dual Mass Flywheel (DMF),where two stages of stiffness properties (Figure 2)were applied to capture shuffle frequency as a function of angular displacement and angular speed.The vehicle inertias were attached to each of wheel inertias to imitate the friction load acting on the system.The torsional system of a 4WD vehicle (Figure 1a )compris of two drive system,namely a FWD system and a RWD system.4WD is engaged by connecting the FWD system through the power take-off unit,and linked to the rear differential unit with propeller shaft and traction control unit.
Figure 2:DMF Characteristic
2.2Single Fore-Aft Model
The chassis sub-system was reprented by the Fore-Aft model as shown in Figure 1(b).It consists of high level components,which have the dominant effect on the vehicle body,front and rear wheels,
power-unit,front and rear sub-frames.Each of the components was connected through nonlinear compliances,and its displacement has been fixed on longitudinal direction except the mass carrier co
mpliances.Both of the mass carrier compliances (right hand and left hand side)have 3DoF to perceive the effect of the
power-unit’s 1st Stage
2nd Stage
Angular Displacement
T o r q u e Angular Speed
Drive
Rever
hentaitubefreepitch and yaw to the vehicle system dynamics.Similarly to Torsional Model,no tyre model has been included to reprent dynamics characteristics of the active force,slip ratio.The characteristics have been replaced by the forces taken from vehicle test data and ud as the inputs to the front and rear wheels to excite the system.
2.3Coupled Model
The architecture of the Coupled Model consists of 40DoF from 4sub-systems and driver environment,.Each component of the sub-systems has the combination of torsional elements,mass,inertias and mechanical properties.From Figure 3,the engine is mounted to the transmission bell housing and the energy from the combustion is transferred to input shaft via DMF.The integrated front differential inside the transmission splits the torque to the front half-shafts and Power Take Off (PTO)unit.The rear differential then divides the torque to right and left side of the rear half-shafts.Both of the front and rear half-shafts are connected to the tyre model to provide the longitudinal force as a function of vertical load and wheel slip ratio.The longitudinal force drives the chassis sub-system where each of the chassis components is inter-connected by the nonlinear compliances.
Figure 3:Coupled Model of 4WD Vehicle Systemngl
A generic tyre model has been developed bad on the standard tyre parameters fitted on this particular vehicle.Car Maker software [5]was ud to generate the 3dimensional data ,on tarmac surface with surface coefficient, =0.85.Fundamentally,the road surface coefficient is reduced as a function of vehicle speed;hence reduce the tractive force further.But this effect has been neglected in
this analytical model.The input torque is controlled by the driver environment block to reprent the combustion process to induce the crank train system.The gear ratio is fixed at 2nd Gear with the assumption that no mechanical loss in the gearing system.By coupling the two single models as discusd earlier,the vehicle model was expected to be more robust and produce true physical reprentation of the sub-system behaviour.The common root caus of vehicle driveability were always associated with the ri rate of the torque demand as well as the overshoot of the oscillation,which can be nd by most drivers [6,7].The explanation for this occurrence was due to the rapid excitation of torque demand to the driveline system and its compliances.With this Coupled Model,it has allowed more accurate study on driveability and to understand the energy flow from throttle demand to the at rail via contact patch of the wheels.
To validate the accuracy and robustness of the Dymola Coupled Model,a correlation was carried out with an ADAMS full nonlinear model and had been verified with vehicle measurement data.The simulation parameters were t-up to be the same as the ADAMS full nonlinear model.
3.
SIMULATION
Driveline
Power Unit例外的意思
Driver Environment Transmission
Chassis
3.1Off-line Simulation
The standard practices of the Tip-In/Tip-Out tests are to accelerate the vehicle up to 45kilometer per hour (kph)and coast down to 30kph.An abrupt torque then applied within 0.12conds to excite the torsional system until it reached maximum torque.And finally the torque will be removed instantaneously from the crank train system.For the simulation t-up,the model was run up to 17conds to replicate the test condition above,with fixed step integrator of 0.001conds.The Euler solver was ud together with Implicit Euler as the inline integration for real time solver.Bad on the single Dymola sub-systems simulation,the correlation results show a good agreement with the single ADAMS models in terms of crank speed and at acceleration as prented in Figure 4and Figure
5.The results verified that the single Dymola Torsional Model and Fore-Aft Model can be ud to f
orm the Coupled Model.For the Coupled Model,the computation time against the ADAMS full nonlinear system has improved significantly from 9hours 30minutes to only 10.5conds.In Figure 6,the crank speed is having the same behavior as full nonlinear model but the oscillation is en been phad in 2nd to 4th orders.However,the discrepancies can be neglected as the occurrence was due to the effect of the generic tyre model properties.The correlation result demonstrates that the Coupled Model has performed the same manner as the ADAMS full nonlinear model.
Figure 4:Correlation results against single ADAMS Torsional Model without tyre model
Figure 5:Correlation results against single ADAMS Fore-Aft Model without tyre modelscience direct
Time [c]S e a t A c c e l e r a t i o n [m /s 2]
Time [c]C r a n k S p e e d [r p m ]
