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4 Sensitivity Analysis
0 1 1.5
0
1
2
3
b
a
x in m2/s
f
s
=0.2
f
s
=0.1 f
s
=0.3
-0.5
0
1
1.5
0
1
2
3
4
Time
0.5
Time
f
s
=0.2
f
s
=0.1
f
s
=0.3
f
s
=0.2
f
s
=0.1
f
s
=0.3
0.5
Figure 4.1.: Left: Representation of the longitudinal versus the lateral acceleration in
the vehicleâs COG with elliptic characteristic. The simulated manoeuvre
starts with pure positive longitudinal acceleration, followed by a combined
longitudinal and lateral acceleration state. The scaling factor fs is used to
scale thedesiredaccelerationprofiles. Topright: Longitudinalacceleration
version timetoachieve thedriving states shownonthe left. Bottomright:
Lateral acceleration versus time.
Time dependence of sensitivity
Simulations with different acceleration profiles versus time have to be compared in order
to be able to evaluate many states within the parameter space. The higher the desired
acceleration is set, the faster a certain state is reached, as shown in Figure 4.2. As
mentioned before, the time at which a certain state (in this case a certain longitudinal
and lateral acceleration) is reached must not influence the calculated sensitivities p.
Thus, the sensitivity p = âz/â” calculated for a certain ba scaled with fs = 1 at t1
has to be the same as the one for fs = 0.5 at t2. For example, Figure 4.3 shows the
driving state with pure bax of 0.45 m/s
2 and bay = 0. It is evident that the selected
sensitivitiesâvx/â”andâÏfl/â”havecongruentcharacteristics independenceof” max at
the investigated longitudinal acceleration of 0.45 m/s2, no matter which scaling factor
fs is used for the desired acceleration profile during the simulation manoeuvre. Both
the tendency and the absolute values at a certain ”max are similar for all simulations.
This behaviour is the same for the all sensitivities pl and for all acceleration points not
displayed. Thus, time-dependence can be excluded.
69
Maximum Tire-Road Friction Coefficient Estimation
- Title
- Maximum Tire-Road Friction Coefficient Estimation
- Author
- Cornelia Lex
- Publisher
- Verlag der Technischen UniversitÀt Graz
- Location
- Graz
- Date
- 2015
- Language
- English
- License
- CC BY-NC-ND 3.0
- ISBN
- 978-3-85125-423-5
- Size
- 21.0 x 29.7 cm
- Pages
- 189
- Category
- Technik