2.5. OPTIMIZATION RESULTS AND ANALYSIS 21
Aggressive
Moderate
Conservative
Aggressive
Moderate
Conservative
Aggressive
Moderate
Conservative
Aggressive
Moderate
Conservative
50
40
30
20
10
0
50
40
30
20
10
0
12
10
8
6
4
2
0
20
15
10
5
0
0 0 1 2 3 4 5 62 4 6
t (s) t (s)
8
0 2 4 6
t (s)
8 0 2 4 6
t (s)
8
10 12
× 10
4
Vehicle Speed (km/h)
(Acceleration)
Vehicle Speed (km/h)
(Deceleration)
Vehicle Jerk (m/s
3
)Regenerated Braking Energy (J)
Figure 2.9: Optimized results for the vehicle under different driving styles.
However, the manipulation of the gains of the active damping controller has small influence on
the acceleration performance, according to the exploration results.
2.5.3 OPTIMIZATION RESULTS OF THE CONSERVATIVE DRIVING
STYLE
Since the controller structure of the conservative style is quite similar to the moderate one, the
related parameters to be optimized (K
P
, K
I
, i
g
, and ˇ) are the same. However, because the
optimization objectives are different under these two styles, the values of the parameters at the
end of the optimization process can be far different, as the subplots (e) and (f ) of Fig. 2.8 show.
2.5.4 COMPARISON AND DISCUSSION
A comparison of the above results is shown in Fig. 2.9. e aggressive style, which favors dy-
namic performance, dominates the acceleration and deceleration events among the three. e
duration of the events of 0–50 km/h acceleration and 50–0 km/h deceleration under aggressive
driving are 5.36 s and 4.16 s, respectively. e conservative style, which is in favor of ride com-
fort and energy efficiency, achieves the best performance in vibration reduction and regenerative
braking. e maximum jerk under conservative driving is below 7 m/s
3
, which is around 1/3 of
22 2. CO-DESIGN OPTIMIZATION FOR CYBER-PHYSICAL VEHICLE SYSTEM
Table 2.5: Optimized performance under different driving styles
Driving Style
Performance
t
acc
/s
t
brk
/s
j
max
/m/s
3
E
reg
/10
4
J
E
ECE
/10
4
J
Aggressive
CPS-based 5.36 4.16 20.47 9.17 64.06
w/o CPS 5.71 4.35 19.21 9.42 63.21
Moderate
CPS-based 7.88 6.04 11.52 10.04 60.19
w/o CPS 9.26 6.35 11.91 9.49 62.06
Conservative
CPS-based 12.27 7.86 6.69 10.60 57.59
w/o CPS 13.56 8.28 10.13 9.35 59.21
that in the aggressive driving. Finally, the moderate style, which sits in between the other two,
achieves a good balance between dynamic performance, ride comfort, and energy efficiency.
To compare the energy efficiency at the vehicle level with designed control protocols and
parameter selections during different driving styles, the standard ECE driving cycle is used.
According to the test data in Table 2.5, the energy consumption of the automated electric vehicle
under the conservative style is 575.9 kJ, which improves the efficiency by over 10%, compared
to the energy used in aggressive driving.
Additionally, a comparison of the results between the CPS based optimization and the
baseline is performed. According to the data listed in Table 2.5, the vehicle with CPS based op-
timization achieves better comprehensive performances in vehicle dynamics, ride comfort, and
energy efficiency, thanks to the co-design of the plant and controller parameters. is demon-
strates the advantages of the newly proposed method over the conventional one.
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