서론 I.
. open loop
(adapted control damper system)
.
. ,
,
.
. open loop
close loop
* (Corresponding Author)
: 2010. 6. 11., : 2010. 7. 20., : 2010. 8. 17.
.
- [1],
[2], [3] LQ [4]
,
.
. 시스템 구성 II.
댐퍼 1. CDC (Continuous Damping Control)
.
[5] MR
[6,7] .
normal reverse [8] . 1
reverse type sky-hook
.
normal type soft hard 40ms, hard soft 12ms
. 차량 신호 및 센서의 구성 2.
CDC
2 . CDC
3 ,
High Tunable Control Algorithm for Semi-active Suspension by a Normal Type CDC Damper
* (Ju Yong Choi1)
1Ulsan Technopark
Abstract: This paper proposes CDC (Continuous Damping Control) algorithm and verifies in multi-body dynamic vehicle. In order to distinguish a road profile on driving, waviness calculated by the filtered vertical-accelerations of sprung and unsprung masses is introduced. Sky-hook control is used at a low waviness road and constant damping level control is used at a high waviness road, where the hard damping level is determined by waviness, roll rate, acceleration, and deceleration. The damping levels of ride, anti-roll, anti-squat, and anti-dive modules are calculated by tuning parameters which is dependent upon vehicle velocity. Therefore this high tunable algorithm is useful to improve the ride and handling performance under various driving conditions. In the simulations, tire and dampers are modelled by SWIFT (Short Wavelength Intermediate Frequency Tire) model and 1st order delay model, and results are compared with conventional damper's.
Keywords: semi-active suspension, continuous damping control, sky-hook control, multi-body dynamics, swift tire model
Copyright© ICROS 2010
2 CAN (Controller Area Network)
, , ,
. 감쇠력 제어 알고리즘 III.
CDC
3
1 , 0
. ,
.
4 ,
. 5
. rebound
compression
Damping
force i=i(Hard-hard)
i=i(Soft-soft)
(a) Normal type
rebound compression
Damping
force i=i(Hard-soft)
i=i(Soft-hard) i=i(Soft-soft)
(b) Reverse type
1. CDC .
Fig. 1. Characteristic of CDC damper.
Vertical G sensors of body (3EA)
Vertical G sensors of wheel (2EA)
CONTROLLER
Vehicle CAN signal
Break signal
Throttle position signal
Vehicle velocity
Lateral G signal
2. CDC .
Fig. 2. Configuration of CDC system.
rebound compression
Damping
force Hard
(damping level = 1)
Damper velocity Soft (damping level = 0) Desired
damping force
Instant velocity
Control damping current
3. CDC .
Fig. 3. Damping level for a normal type CDC damper.
Road Detecting Module
Ride Damping Module Anti-squat
Module Anti-dive
Module Anti-roll
Module Calculation of Damping Level
Calculation of Damping Force Vertical acceleration
Multi-body Vehicle Dynamics Throttle position
Vehicle velocity Break signal Vehicle velocity Lateral acceleration Vehicle velocity
(road amplitude) (waviness)
(damping level [0~1])
damper velocity (damping force)
< Control Logic >
4. CDC .
Fig. 4. Constitution of CDC system.
Tuning functions
Vehicle velocity
V1 V2 V3 V4
Stop Low speed
Middle speed
speedHigh
5. .
Fig. 5. Tuning parameters according to vehicle velocity.
필터 설계 1.
CDC digital
.
high pass, low pass band pass
/ dc offset
. (1) 2
1 .
⋅
⋅ (1)
HPF (High Pass Filter)
0.5~25Hz cut-off
0.2Hz
. DC
0.3
. LPF (Low Pass Filter)
HPF
cut-off . 6
HPF LPF .
제어 2. Sky-hook
Sky- hook
Karnopp [9]
[10]. ,
.
Sky-hock .
Damping level (2)
노면판단 및 승차감 감쇠 모듈 3.
sprung, unsprung , ,
(4) 7 .
(3) 1.25Hz,
13Hz BPF band-pass
.
(4)
moving average ,
waviness ( )
(5) .
(5)
, waviness ( ) Sky-
1. .
Table 1. Parameters for each filter.
[Hz]
integrator with
High pass filter 1 ⋅⋅ 0.1~0.5 Band Pass filter (BPF) ⋅⋅ ⋅⋅ 10~15
Differentiator with
Low pass filter
⋅⋅ 3~5
6. .
Fig. 6. Frequency responses of filters.
zus
Integrator with HPF
(m z m zs⋅ +s u⋅us)/kt
Integrator with HPF zs
zus
+
BPF
(13 Hz) |abs| Moving
Average ÷
BPF
(1.25 Hz) |abs| Moving Average
W
R high
z−
R low
z −
zus
ms
mu
kt
zs
zR
zR
7. .
Fig. 7. Road detection module.
hook
.
, (6)
.
≦
(6)
,
. hard
Hard
.
30km/h
. waviness
sky-hook
anti-roll, anti-squat anti-dive . 조종안정성 제어 모듈
4.
모듈 4.1 Anti-roll
(roll)
static gain (roll-rate)
.
.
× (7)
40 km/h .
under-steer .
모듈 4.2 Anti-squat
squat (pitch)
accel
anti-squat
(8) .
TPS(throttle position sensor)
. TPS
.
(8) 모듈
4.3 Anti-dive
dive . anti-dive
on ,
decel
dive
.
(9)
.
10 km/h
. 감쇠력계산 모듈
5.
8 waviness sky-hook
. ≦
soft 0 hard
(10)
sky-hook .
× × × (10)
( , ≦ ) 0
, 0
hard sky-hook
. ≦
.
. 9
1
0
Damping Level
Hard damping level Soft damping level
Waviness
Hard low
D −
Hard high Soft high
D − =D −
Soft low
D −
(long wave road) (Short wave road) Sky-hook control Constant damping level control
wlow wc whigh wres
8. .
Fig. 8. Calculation of damping level.
.
2
. CDC CDC hard
soft
.
.
시스템 모델링 IV.
차량 및 댐퍼 모델링
1. CDC
CDC 4
SUV , 4
ADAMS
. ,
CDC 1
.
타이어 모델링 2.
‘SWIFT’
. ‘SWIFT’ handling
MF (Magic Formula) slip force ,
‘Rigid Ring’
zus
Integrator with HPF
(m z m zs⋅ +s u⋅us)/kt Integrator with HPF zs
zus
+ BPF |abs| Moving
Average
W
zR Integrator
with HPF
( ) 0
s s us
z z z − > No 0 Yes
Differentiator with LPF
Break Signal = On
Yes decel
|abs|
Differentiator with LPF Throttle
Position accel
v
R low
z−
R high
z−
Break Signal v
Differentiator with LPF ay
θest
No 1
wc
W >
Road Squat Dive Roll 1 d ×d ×d ×d −
Calculation of Damping Force
Multi-body Vehicle Dynamics
1 1 s τ + v
Yes No
Damper velocity
Roll angle estimation
Anti-roll damping level (dRoll) Anti-dive
damping level (dDive) Anti-squat damping level (dSquat)
|abs|
9. CDC .
Fig. 9. Overall CDC logic.
2. ( : , : , : ).
Table 2. Tuning parameters for each module.
Module Tuning
parameter
Driving condition Vehicle behavior Parameter selection
road maneuvering vertical
G roll rate
pitch rate
low speed
mid speed
high speed
Ride
long wave = 40~60 km/h, straight - - Middle Small High
broken surface = 10~30 km/h, straight - - Small Middle High
Belgian = 10~20 km/h, straight Small Middle High
Handling
anti-roll
Highway
= 40~100 km/h, double lane change
- - High Small Small
- - rear even front
anti-squat = 0~100 km/h, straight - - - - -
anti-dive = 80~40 km/h, straight - - Small middle middle
10. CDC .
Fig. 10. Vehicle modeling for the CDC control.
flexible ‘Tire Rim’
.
50~60Hz, /
100Hz ,
‘MF-Tire’
15° , 100% , 5°
. Ride
. 시뮬레이션 결과 V.
Sky-hock
.
Sky-hock (2) Soft
Hard [10].
⋅⋅ (11)
,
. 승차감 1.
(bouncing)
. 11 90mm, 12m sine
80km/h ,
. 0.2882deg/s Sky-hook
7.0358m/s2 .
.
. 조종안정성 2.
0 2 4 6 8
-3000 -2000 -1000 0 1000 2000 3000 4000
Damping force [N]
Time [sec]
Sky-hook Proposed
0 2 4 6 8
-0.4 -0.2 0.0 0.2 0.4
Pitch rate [deg/s]
Time [sec]
Sky-hook Proposed
0 2 4 6 8
-8 -6 -4 -2 0 2 4 6 8
Vertical acceleration [m/s
2]
Time [sec]
Sky-hook Proposed
11. .
Fig. 11. Long wave road simulations.
0 2 4 6 8
-1000 0 1000 2000 3000
Damping force [N]
Time [sec]
Sky-hook Proposed
0 2 4 6 8
-0.4 -0.2 0.0 0.2 0.4
Roll rate [deg/s]
Time [sec]
Sky-hook Proposed
12. sin .
Fig. 12. sin wave steering simulations.
0 2 4 6 8 -300
-200 -100 0 100 200 300
Damping force [N]
Time [sec]
Sky-hook Proposed
0 2 4 6 8
-0.15 -0.10 -0.05 0.00 0.05 0.10 0.15
Pitch rate [deg/s]
Time [sec]
Sky-hook Proposed
13. .
Fig. 13. Squat simulations.
0 2 4 6 8
-3000 -2000 -1000 0 1000 2000 3000
Damp ing fo rce [N ]
Time [sec]
Sky-hook Proposed
0 2 4 6 8
-0.15 -0.10 -0.05 0.00 0.05 0.10 0.15
Pitc h ra te [d eg/s ]
Time [sec]
Sky-hook Proposed
14. .
Fig. 14. Squat simulations.
. 12
80km/h 80 , 1 sin
0.3207deg/s
0.2546deg/s . 13 40km/h 80
km/h squat
0.0822deg/s
0.0745deg/s . dive 80km/h 40km/h
14 4
.
,
. 결론 VI.
. / ,
hard soft ,
,
.
.
.
.
HILS (Hardware-In-the-Loop Simulation) .
참고문헌
[1] H. W. Woo and J. Ryu, “A new double sky-hook algorithm for improving road-holding property in semi-active suspension Systems,” Trans. Korean Society of Automotive Engineers, vol. 7, no. 1, pp. 192-200, Jan.
1999.
[2] K. S. Yi, M. W. Suh, and T. I. Oh, “A robust semi-active suspension control law,” Trans. Korean Society of Automotive Engineers, vol. 2, no. 6, pp.
117-126, Nov. 1994.
[3] S.-G. So, “A study on the semi-active suspension systems applying fuzzy logic,” J. of Korean Institute of Intelligent Systems, vol. 10, no. 1, pp. 52-57, Feb. 2000.
[4] J. Kim and K. Yi, “States/road input observer-based control of semi-active suspensions,” J. of Korean Society
for Precision Engineering, vol. 8, no. 2, pp. 102-109, Mar. 2000.
[5] S.-J. Heo and K. Park, “Analysis of continuously variable damper characteristics for semi-active suspension systems,” J. of Korean Society for Precision Engineering, vol. 20, no. 7, pp. 128-137, Jul. 2003.
[6] J. W. Park and Y. D. Jung, “Magnetic circuit design methodology of MR CDC dampers for semi-active suspensions,” J. of Korean Society for Precision Engineering, vol. 20, no. 10, pp. 48-57, Oct. 2008.
[7] Y.-J. Nam, D.-U. Kim, M.-K. Park, and Y.-H. Lee,
“Design and performance investigation of bypass-tType MR shock dampers,” Trans. Korean Society of Mechanical Engineers A, vol. 30, no. 5, pp. 550-559, May 2006.
[8] Y.-H. Yoon, M.-J. Choi, and K.-H. Kim, “Development of a reverse continuous variable damper for semi-active suspension,” Int. J. of Automot. Techn., vol. 3, no. 1,
pp. 27-32, Mar. 2002.
[9] D, C. Karnopp, M. J. Crosby, and R. A. Harwood,
“Vibration control using semi-active force generators,”
ASME Journal of Engineering for Industry, vol. 96, no.
2, pp. 619-626, 1974.
[10] Y. H. Lee and M. K. Park, “Skyhook control of a semi-Active ER damper,” J. of Korean Society of Precision Engineering, vol. 18, no. 1, pp 56-62, Jan.
2001.
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1998 . 2000
. 2005 . 2005 ~2009
. 2009 ~
. ,
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