Apparatus for controlling semi-active suspension system

• US 6,507,778 B2
• Filed: 01/05/2001
• Issued: 01/14/2003
• Est. Priority Date: 01/05/2001
• Status: Active Grant

• Current Assignee: Mando Corporation
• Original Assignee: Mando Corporation
• Inventors: Koh, You-Seok
• Primary Examiner(s): Chin, Gary
• Application Number:
  US09/755,808
• Publication Number:
  US 20020133277A1
• Time in Patent Office: 739 Days
• Field of Search: 701/37, 701/38, 701/39, 280/5.503, 280/5.508, 280/5.515, 280/5.519, 280/5.506
• US Class Current: 701/37
• CPC Class Codes: B60G 17/016 characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input B60G17/017 takes precedence
• CPC Class Codes: B60G 17/0165 to an external condition, e.g. rough road surface, side wind
• CPC Class Codes: B60G 17/08 Characteristics of fluid dampers adjusting fluid dampers in general F16F9/44 - F16F9/53
• CPC Class Codes: B60G 2400/0511 Roll angle
• CPC Class Codes: B60G 2400/102 vertical
• CPC Class Codes: B60G 2400/202 Piston speed; Relative velocity between vehicle body and wheel
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2400/206 Body oscillation speed; Body vibration frequency
• CPC Class Codes: B60G 2400/41 Steering angle
• CPC Class Codes: B60G 2500/10 Damping action or damper
• CPC Class Codes: B60G 2600/184 Semi-Active control means
• CPC Class Codes: B60G 2600/604 low pass
• CPC Class Codes: B60G 2800/012 Rolling condition
• CPC Class Codes: B60G 2800/162 Reducing road induced vibrations
• CPC Class Codes: B60G 2800/24 Steering, cornering
• CPC Class Codes: B60G 2800/9122 ARS - Anti-Roll System Control
• CPC Class Codes: B60G 2800/916 Body Vibration Control
• CPC Class Codes: F16F 9/535 Magnetorheological [MR] fluid dampers springs comprising magnetorheological [MR] elastomers F16F1/361

Abstract

An apparatus for controlling a semi-active suspension system of a vehicle including at least one shock absorber using magneto-rheological fluids. The shock absorber has a rebound valve and a compression valve which are configured such that damping forces of the shock absorber generated in rebound strokes and compression strokes being controlled independently. The apparatus comprises a normal driving control unit for determining a ride value (S_ride) and a filtered vehicular vertical velocity (v_i) based on a vertical vehicular acceleration, an anti-roll control unit for determining a roll value (S_roll) based on a velocity and a steering angle of the vehicle, and a damping force adjusting unit for controlling the rebound valve and the compression valve of the shock absorber based on the roll value (S_roll), the ride value (S_ride) and the filtered vehicular vertical velocity (v_i) under a predetermined condition.

Claims

1. An apparatus for controlling a semi-active suspension system of a vehicle including at least one shock absorber using magneto-rheological fluids, the shock absorber having a rebound valve and a compression valve which are configured such that damping forces of the shock absorber generated in rebound strokes and compression strokes are controlled independently of each other, the apparatus comprising:

a normal driving control unit for determining a ride value (S_ride) and a filtered vehicular vertical velocity (v_i) based on a vehicular vertical acceleration;

an anti-roll control unit for determining a roll value (S_roll) based on a velocity and a steering angle of the vehicle; and

a damping force adjusting unit for controlling the rebound valve and the compression valve of the shock absorber based on the roll value (S_roll), the ride value (S_ride) and the filtered vehicular vertical velocity (v_i) under a predetermined condition.

2. The apparatus of claim 1, wherein the normal driving control unit includes an integrator for determining a vehicular vertical velocity (v^h) by integrating the vehicular vertical acceleration (a) detected by an acceleration sensor, a filtering part for determining the filtered vertical velocity (v_i) based on the vehicular vertical acceleration (a) and the vehicular vertical velocity (v^h) and a ride value calculating part for calculating the ride value (S_ride) based on the vehicular vertical velocity (v^h) and the filtered vertical velocity (vⁱ).

3. The apparatus of claim 2, wherein the integration operation of the integrator is performed such that the following equation holds:

$\frac{v^h<br><br>\left(z\right)}{a<br><br>\left(z\right)}=\frac{0.00345<br><br>z^2-0.00345}{z^2-1.969<br><br>z+0.96968}$

wherein

a(s) is the vertical vehicular acceleration, and

v^h(s) is the vehicular vertical velocity.

4. The apparatus of claim 2, wherein the filtered vertical velocity (v_i) is determined such that the following equations hold:

$\begin{array}{c}\frac{a^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}<br><br>\left(z\right)}{a<br><br>\left(z\right)}=\frac{0.11179<br><br>\text{\hspace{1em}<br><br>}<br><br>z^2-0.11179}{z^2-1.6125<br><br>z+0.77642}\\ a_{\mathrm{sq}}^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}<br><br>\left(z\right)={\left(a^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}<br><br>\left(z\right)\right)}^2\\ \frac{{\stackrel{\_}{a}}_{\mathrm{sq}}^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}<br><br>\left(z\right)}{a_{s<br><br>\text{\hspace{1em}<br><br>}<br><br>q}^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}<br><br>\left(z\right)}=\frac{0.06195<br><br>z+0.06195}{z-0.87611}<br><br><br><br>v_i=\frac{v^h}{1+K_v·<br><br>{\stackrel{\_}{a}}_{\mathrm{sq}}^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}}\end{array}$

wherein

K_v is a gain having a predetermined value.

5. The apparatus of claim 2, wherein the ride value (S_ride) is calculated such that the following equations hold:

6. The apparatus of claim 2, wherein the integration operation of the integrator is performed such that the following equation holds:

$\frac{v^h<br><br>\left(s\right)}{a<br><br>\left(s\right)}=\frac{s}{s^2+2<br><br>{\mathrm{\zeta <br><br>}}_1<br><br>{\mathrm{\omega <br><br>}}_1<br><br>s+{\mathrm{\omega <br><br>}}_1^2}$

wherein

a(s) is the vertical acceleration, and

v^h(s) is the vehicular vertical velocity.

7. The apparatus of claim 2, wherein the filtered vertical velocity (v_i) is determined such that the following equations hold:

$\frac{a^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}<br><br>\left(s\right)}{a<br><br>\left(s\right)}=\frac{2<br><br>{\mathrm{\zeta <br><br>}}_2<br><br>{\mathrm{\omega <br><br>}}_2<br><br>s}{s^2+2<br><br>{\mathrm{\zeta <br><br>}}_2<br><br>{\mathrm{\omega <br><br>}}_2<br><br>s+{\mathrm{\omega <br><br>}}_2^2},{\mathrm{\zeta <br><br>}}_2=0.3,{\mathrm{\omega <br><br>}}_2=10\times <br><br>2<br><br>\mathrm{\pi <br><br>}$$a_{\mathrm{sq}}^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}<br><br>\left(s\right)={\left(a^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}<br><br>\left(s\right)\right)}^2$$\frac{{\stackrel{\_}{a}}_{\mathrm{sq}}^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}<br><br>\left(z\right)}{a_{\mathrm{sq}}^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}<br><br>\left(z\right)}=\frac{1}{\mathrm{Ts}+1},T=0.053$$v_i=\frac{v^h}{1+K_v·<br><br>{\stackrel{\_}{a}}_{\mathrm{sq}}^{10<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{Hz}}}$

wherein

K_v is a gain having a predetermined value.

8. The apparatus of claim 2, wherein the ride value (S_ride) is calculated such that the following equations hold:

9. The apparatus of claim 1, wherein the anti-roll control part includes a steering rate detecting part for determining a lateral acceleration (a_y) based on the velocity and the steering angle of the vehicle and a roll value calculating part for determining the roll value (S_roll) based on the lateral acceleration (a_y).

10. The apparatus of claim 9, wherein the lateral acceleration (a_y) is determined such that the following equation holds:

$a_y=\frac{V^2}{l}\times <br><br>\frac{1}{1+{\left(\frac{V}{V_{\mathrm{ch}}}\right)}^2}\times <br><br>\frac{{\stackrel{.}{\mathrm{\delta <br><br>}}}_{\mathrm{sw}}}{i_s}$

wherein

i_s is a steering gear ratio,

{dot over (δ

)}_sw is a steering wheel angle ratio,

l is a length of wheel base,

V is a vehicular velocity, and

V_ch is a characteristic velocity.

11. The apparatus of claim 9, wherein the roll value (S_roll) is calculated such that the following equation holds:

12. The apparatus of claim 9, wherein the roll value (S_roll) is calculated such that the following equation holds:

13. The apparatus of claim 1, wherein, when the roll value (S_roll) is larger than a predetermined value, an amount of control current for the rebound valve (A_R) and that for the compression valve (A_C) of the shock absorber are determined such that the following equations hold:

$A_R=3·<br><br>\frac{S_{\mathrm{iR}}}{128}$$A_C=3·<br><br>\frac{S_{\mathrm{iC}}}{128}$

wherein the subscript R stands for rebound and the subscript C for compression,

14. The apparatus of claim 13, wherein, when S_iR is greater than 128, the amount of control current for the rebound valve (A_R) has a value of 3.

15. The apparatus of claim 13, wherein, when S_iC is greater than 128, the amount of control current for the compression valve (A_C) has a value of 3.

16. The apparatus of claim 1, wherein, when the roll value (S_roll) is smaller than a predetermined value, an amount of control current for the rebound valve (A_R) and that for the compression valve (A_C) of the shock absorber are determined by the damping force adjusting unit such that the following equations hold:

$A_R=3·<br><br>\frac{S_{\mathrm{iR}}}{128}$$A_C=3·<br><br>\frac{S_{\mathrm{iC}}}{128}$

wherein the subscript R stands for rebound and the subscript C for compression and

17. The apparatus of claim 16, wherein, when S_iR is greater than 128, the amount of control current for the rebound valve (A_R) has a value of 3.

18. The apparatus of claim 16, wherein, when S_iC is greater than 128, the amount of control current for the compression valve (A_C) has a value of 3.