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386 Multibody Systems Approach to Vehicle Dynamics
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LINKAGE MODEL – 100 km/h LANE CHANGE
Track test
ADAMS
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Yaw rate (deg/s)
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Time (s)
Fig. 6.56 Yaw rate comparison – linkage model and test. (This material has
been reproduced from the Proceedings of the Institution of Mechanical
Engineers, K2 Vol. 214 ‘The modelling and simulation of vehicle handling.
Part 4: handling simulation’, M.V. Blundell, page 81, by permission of the
Council of the Institution of Mechanical Engineers)
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behaviour. Such a ‘difference’ is commonly referred to as ‘error’. This definition
neatly sidesteps two other difficulties:
● Is the measured data what actually happens in the absence of
measurement?
● Is the measured data what actually happens during service?
For example, the mass-loading effect of accelerometers may introduce
inaccuracies at high frequencies and could mean that the system of interest
behaves differently when being measured to when not. The accuracy of
controlled measurements in discerning the behaviour of the system when in
normal uncontrolled use is another matter entirely. Both topics are far from
trivial.
In this case other questions arise such as:
● Does the model data accurately represent the vehicle conditions on the
day of the test?
● Does the tyre test data obtained on a tyre test machine accurately represent
the condition of the test surface and tyres used on the day of the
test?
● How repeatable are the experimental test results used to make an assessment
of model accuracy?
● Is there a model data input error common to all the models?
Comparing the performance of the equivalent roll stiffness model with that
of the linkage model in Figures 6.55 and 6.56 it is possible to look, for