Suspension control device, vehicle comprising said device, production and associated program

• US 7,949,445 B2
• Filed: 09/13/2006
• Issued: 05/24/2011
• Est. Priority Date: 09/22/2005
• Status: Expired due to Fees

• Current Assignee: Peugeot Citroen Automobile SA (Stellantis NV)
• Original Assignee: Peugeot Citroen Automobile SA (Stellantis NV)
• Inventors: Poilbout, Francois
• Primary Examiner(s): Keith; Jack
• Assistant Examiner(s): Shafi; Muhammad
• Application Number:
  US12/067,779
• Publication Number:
  US 20080300752A1
• Time in Patent Office: 1,714 Days
• Field of Search: 701/37, 701/91, 701/38, 701/48, 280/5.5, 280/5.501, 280 5504- 5509, 280 5512- 5515, 280/6.157, 702/141, 702/151, 702/152, 180/232, 180/41
• US Class Current: 701/37
• CPC Class Codes: B60G 17/0161 mainly during straight-line motion B60G17/0164 takes precedence
• CPC Class Codes: B60G 17/0165 to an external condition, e.g. rough road surface, side wind
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method
• CPC Class Codes: B60G 17/019 characterised by the type of sensor or the arrangement thereof B60G17/01941 takes precedence
• CPC Class Codes: B60G 2204/116 Sensors coupled to the suspension arm
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• 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 2400/252 vertical
• CPC Class Codes: B60G 2400/821 Uneven, rough road sensing affecting vehicle body vibration
• CPC Class Codes: B60G 2500/10 Damping action or damper
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/14 Differentiating means, i.e. differential control
• CPC Class Codes: B60G 2800/91 Suspension Control

Abstract

A device for controlling the suspension of the body shell of a motor vehicle performs calculation of a relative modal body shell speed in relation to the mid-plane of the wheels, and calculation of the set modal stress of the damper as a function of the relative modal body shell speed in relation to the mid-plane of the wheels. The control value includes a determined shock absorption principle from among a plurality of different shock absorption principles that impose the force of the damper as a function of its travel speed.

Claims

1. Suspension control device for a motor vehicle body on its wheels (A), having a computer (CSS) configured to calculate a control magnitude (ER) for an actuator (M) of at least one variable damper (AM) of the suspension (S) as a function of at least one modal setpoint force for the body, wherein the control magnitude (ER) is a damping law that sets a damper force (FA) for the damper (AM) as a function of a displacement speed (VDEB) of at least one of the wheels (A),

said computer (CSS) having

first means for calculating at least one absolute body modal velocity (V_mod1) of at least one of the wheels (A),

second means for calculating a first modal setpoint force (F₁) for the damper, as a function of the absolute body modal velocity (V_mod1) of the wheel (A),

third means for calculating at least one relative body modal velocity (V_mod2) of the wheel (A) with respect to the mid-plane of the wheels,

fourth means for calculating a second modal setpoint force (F₂) for the damper, as a function of the relative body modal velocity (V_mod2) with respect to the mid-plane of the wheels,

fifth means for calculating a setpoint force (F) as a function of the first modal setpoint force (F₁), the second modal setpoint force (F2), and a weighting coefficient (α

), using the formula;

F=α

·

F₂+(1−

α

)·

F₁

wherein

the control magnitude (ER) for the actuator (M) of the damper (AM) is selected from among a plurality of different damping laws (ER), wherein each of said damping laws (ER) sets the damper force (FA) for the damper (AM) as a function of the displacement speed (VDEB) of the wheel (A), by selecting the damping law (ER) closest to the point having the coordinates (displacement speed (VDEB), setpoint force (F)).

2. Suspension control device according to claim 1, which comprises at least one sensor (CAP-DEB) for displacement of a wheel (A, B, C, D) with respect to the vehicle body, the third means for calculating relative body modal velocity (V_mod2) being configured to calculate said relative body modal velocity (V_mod2) with respect to the mid-plane of the wheels as a function of at least the displacement (DEB) provided by the displacement sensor (CAP-DEB).

3. Suspension control device according to claim 1, wherein the third means for calculating relative body modal velocity (V_mod2) comprises a low-pass filter for the displacement (DEB) provided by the displacement sensor (CAP-DEB) and a derivation circuit for obtaining said relative body modal velocity (V_mod2) with respect to the mid-plane of the wheels.

4. Suspension control device according to claim 1, wherein the mode is at least one from among vertical heave (z), roll (θ

) and pitch (φ

).

5. Suspension control device according to claim 4, wherein a displacement sensor (CAP-DEB) is provided for each wheel (A, B, C, D), and the third means for calculating relative body modal velocity (V_mod2) is configured to calculate at least one of the following relative modal velocities (V_mod2):

the relative body heave modal velocity ż

_G2 with respect to the mid-plane of the wheels, using the formula;

6. Suspension control device according to claim 5, characterized in that the computer (CSS) comprises a means for calculating the distance (Ig) between the center of gravity (G) and the front wheel (A, B) axle, using the formula

lg=(1−

RMAvAr)·

e

where

RMAvAr is a front-rear mass distribution value.

7. Suspension control device according to claim 6, which comprises a means for measuring the vehicle speed (VVH),

the means for calculating the distance (lg) between the center of gravity (G) and the front wheel (A, B) axle being configured to calculate the front-rear mass distribution value (RMAvAr) as a function of the displacements provided by the displacement sensors (CAP-DEB) and the vehicle speed (VVH).

8. Suspension control device according to claim 1, wherein the fourth means for calculating the second modal setpoint force includes

a first means for calculating a first anticipatory modal force term as a function of a set vehicle body jerk,

a second means for calculating a second corrective modal force term as a function of said relative body modal velocity (V_mod2) with respect to the mid-plane of the wheels,

a third means for calculating the modal setpoint force (c_φ

2, c<sub>θ

2</sub>, F_z2) as a function of the first anticipatory modal force term and the second corrective modal force term.

9. Suspension control device according to claim 8, wherein the third means for calculating the modal setpoint force (c_φ

2, c<sub>θ

2</sub>, F_z2) is configured to calculate the modal setpoint force (c<sub>φ

2</sub>, c<sub>θ

2</sub>, F_z2) by selecting

the second corrective modal force term when the absolute value of the anticipatory modal force term is less than or equal to a first prescribed non-zero value,

the first anticipatory modal force term when the absolute value of the first anticipatory modal force term is greater than the first prescribed value and when the absolute value of the second corrective modal force term is less than or equal to a second prescribed non-zero value,

when the absolute value of the first anticipatory modal force term is greater than the first prescribed value, and when the absolute value of the second corrective modal force term is greater than the second prescribed value,

whichever of the first anticipatory modal force term and the second corrective modal force term has the highest absolute value, when the first anticipatory modal force term and the second corrective modal force term have the same sign,

the second corrective modal force term when the first anticipatory modal force term and the second corrective modal force term have opposite signs.

10. Suspension control device according to claim 8, wherein a displacement sensor (CAP-DEB) is provided for each wheel (A, B, C, D),

the means for calculating the second corrective modal force term is configured to calculate a second corrective modal gain b_mod2 for variable damping from at least the wheel displacement measurements provided by said displacement sensors (CAP-DEB) in order to calculate a second corrective modal force term F_2COR, using the formula:

F_2COR=−

b_mod2·

V_mod2.

11. Suspension control device according to claim 10, wherein

the means for calculating the second corrective modal force term is configured to calculate a second corrective modal gain (b_mod2) for variable damping such that this second corrective modal gain (b_mod2) includes at least one driving mode multiplier coefficient (b_zTYP, b_θ

TYP, b<sub>φ

TYP</sub>), which is equal to a prerecorded sportive mode gain in the event that a sport driving mode control button on the vehicle dashboard is in a sportive driving mode position, and which is equal to one in the event that the sport driving mode control button is in a non-sport driving mode position.

12. Suspension control device according to claim 10, which comprises a means for measuring the vehicle speed (VVH), and the means for calculating the second corrective modal force term is configured to calculate the second corrective modal gain (b_mod2) for variable damping such that this second corrective modal gain (b_mod2) for variable damping includes at least one reference multiplier coefficient (b_zREF, b_θ

REF, b<sub>φ

REF</sub>), calculated as a function of the measured vehicle speed (VVH).

13. Suspension control device according to claim 10, wherein the means for calculating the second corrective modal force term is configured to calculate the second corrective modal gain (b_mod2) for variable damping such that this second corrective modal gain (b_mod2) for variable damping includes at least one reset multiplier coefficient (b_zREC, b_θ

REC, b<sub>φ

REC</sub>),

the reset multiplier coefficient (b_zREC) for heave is equal to

14. Suspension control device according to claim 7, which comprises:

a means for measuring the vehicle speed (VVH),

a means for calculating a front static attitude (ASav) and a rear static attitude (ASar) for the vehicle from the displacement measurements (DEBF) provided by the displacement sensors,

a means for calculating a front apparent dynamic mass (MDAAV) and a rear apparent dynamic mass (MDAAR) from the displacement measurements (DEB) provided by the displacement sensors (CAP-DEB),

a means for calculating a front aerodynamic bias (BAAV) and a rear aerodynamic bias (BAAR) from the vehicle speed (VVH),

a means for calculating the vehicle sprung mass (MSUS) and a front-rear mass distribution value (RMAvAr) for the vehicle from the front apparent dynamic mass (MDAAV), the rear apparent dynamic mass (MDAAR), the front aerodynamic bias (BAAV) and the rear aerodynamic bias (BAAR).

15. Suspension control device according to claim 14, wherein

the means for calculating the front static attitude (ASav) and the rear static attitude (ASar) of the vehicle is configured to calculate the front (ASav) or rear (ASar) static attitude, respectively, as the mean displacement (DEBAVMOY) of the displacements (DEB) of the front wheels (A, B) or rear wheels (C, D), respectively, filtered through a low-pass filter, to which a respective front or rear attitude offset constant is then added.

16. Suspension control device according to claim 14, wherein

the means for calculating the front and rear apparent dynamic masses (MDAAV, MDAAR) comprises means for

calculating the relative front or rear displacement, equal to the mean displacement of the displacements (DEB) of the front wheels (A, B) or the rear wheels (C, D), respectively, to which a respective front or rear offset constant is then added,

retrieving a front EDFAV or rear EDFAR spring flexure dynamic load value from a recorded table or curve that gives this load EDFAV or EDFAR as a function of the respective front or rear relative displacement,

calculating the respective front MDAAV or rear MDAAR apparent dynamic mass, using the formula:

MDAAV=(EDFAV·

2/g)+front constant,

MDAAR=(EDFAR·

2/g)+rear constant,

where g is the gravity acceleration constant=9.81 m/s<sup>−

2</sup>.

17. Suspension control device according to claim 14, wherein

the means for calculating the vehicle sprung mass (MSUS) and the front-rear mass distribution value (RMAvAr) for the vehicle comprises at least one low-pass filter (PB1, PB2) for the sum of the respective front (MDAAV) or rear (MDAAR) apparent dynamic mass, and the respective front (BAAV) or rear (BAAR) aerodynamic bias, in order to obtain a respective front (MSUSAV) or rear (MSUSAR) sprung mass,

the sprung mass (MSUS) being equal to the sum of the front sprung mass (MSUSAV) and the rear sprung mass (MSUSAR),

the vehicle front-rear mass distribution value (RMAvAr) being equal to the front sprung mass (MSUSAV) divided by the vehicle sprung mass (MSUS).

18. Suspension control device according to claim 17, which comprises an opening panel information unit (10) input means,

the means for calculating the vehicle sprung mass (MSUS) and the front-rear mass distribution value (RMAvAr) is configured to record successive values for the respective front (MSUSAV) or rear (MSUSAR) sprung mass, and to retain the previously recorded value of the respective front (MSUSAV) or rear (MSUSAR) sprung mass instead of its subsequent value when at least one of the following conditions is met:

the vehicle speed (WH) is not between a preset low threshold (VVH1) and a preset high threshold (VVH2),

the opening panel information unit (10) indicates that this opening panel of the vehicle is open and the vehicle speed (VVH) is not greater than a prescribed threshold (VVH3),

the difference between said previously recorded value (MSUSEAVF(n−

1)) for the respective front (MSUSAV) or rear (MSUSAR) sprung mass and its subsequent value (MSUSEAVF(n)) has an absolute value less than or equal to a prescribed difference (Δ

).

19. Suspension control device according to claim 14, which comprises:

a means for calculating the roll moment of inertia (l_θ

) and the pitch moment of inertia (l_φ

) as a function of the sprung mass (MSUS) and the vehicle front-rear mass distribution value (RMAvAr),

a means for calculating the distance (lg) between the center of gravity (G) and the front wheel (A, B) axle,

a means for calculating a heave modal stiffness (k_z), a pitch modal stiffness (k_φ

) and a roll modal stiffness (k_θ

) as a function of the static attitude (AS) and the front-rear mass distribution value (RMAvAr).

20. Suspension control device according to claim 19, wherein said calculating means is configured to calculate:

the roll moment of inertia I_θ

, using the formula I_θ

=A_y·

MSUSAR+B_y

where A_y and B_y are preset parameters,

MSUS is the vehicle sprung mass,

RMAvAr is the front-rear mass distribution value,

MSUSAR is the rear sprung mass of the vehicle, equal to

MSUSAR=(1−

RMArAv)·

MSUS

the pitch moment of inertia I_φ

, using the formula

I_φ

=A_x·

MSUS+B_x

where A_x and B_x are preset parameters.

21. Suspension control device according to claim 19, wherein the means for calculating the distance (Ig) between the center of gravity (G) and the front wheel (A, B) axle is configured to calculate said distance lg between the center of gravity (G) and the front wheel (A, B) axle using the formula

lg=(1−

RMAvAr)·

e

where

RMAvAr is the front-rear mass distribution value,

e is the predetermined wheelbase of the vehicle.

22. Suspension control device according to claim 19, wherein the means for calculating the modal stiffnesses is configured to calculate

the heave modal stiffness k_z as the sum of a front suspension stiffness kAV and a rear suspension stiffness kAR

the pitch modal stiffness k_φ

, using the formula

k_φ

=kAV·

(lg)²+kAR·

(e−

lg)²

the roll modal stiffness k_θ

, using the formula

k_θ

=Kbadav+Kbadar+v²·

(kAV+kAR)/4

where the respective front kAV and rear kAR suspension stiffnesses are obtained by using a prerecorded table or curve that gives the respective front or rear suspension stiffness as a function of the respective front or rear static attitude to retrieve the respective front or rear stiffness value that corresponds to the calculated respective front or rear static attitude ASav,

where Kbadav is a predetermined parameter corresponding to the stiffness of a front anti-roll bar of the vehicle,

Kbadar is a predetermined parameter corresponding to the stiffness of a rear anti-roll bar of the vehicle.

23. Suspension control device according to claim 8, which comprises a means for calculating an anticipated longitudinal jerk () and a means for calculating an anticipated transverse jerk (),

the first means for calculating the first anticipatory modal force term being configured to calculate an anticipatory pitch modal torque (c_φ

2ant) as a function of the anticipated longitudinal jerk () and an anticipatory roll modal torque (c<sub>θ

2ant</sub>) as a function of anticipated transverse jerk ().

24. Suspension control device according to claim 23, wherein the first means for calculating the first anticipatory modal force term comprises:

a filter for canceling the low amplitudes of the anticipated longitudinal jerk () and anticipated transverse jerk (), respectively,

a module for maintaining maxima of the filtered anticipated longitudinal (_T) and transverse) (_T) jerk, respectively,

a slope-limiting module for the respective jerk coming from the module for maintaining maxima, for obtaining a processed anticipated longitudinal (_T) and transverse (_T) jerk, respectively, which are respectively multiplied by a longitudinal stress gain (G_SX) to obtain the anticipatory pitch torque (c<sub>φ

2ant</sub>), and by a transverse stress gain (G_SY) to obtain the anticipatory roll torque (c<sub>θ

2ant</sub>).

25. Suspension control device according to claim 14, wherein the fourth means for calculating the second modal setpoint force includes

a first means for calculating a first anticipatory modal force term as a function of a set vehicle body jerk,

a second means for calculating a second corrective modal force term as a function of said relative body modal velocity (V_mod2) with respect to the mid-plane of the wheels,

a third means for calculating the modal setpoint force (c_φ

2, c<sub>θ

2</sub>, F_z2) as a function of the first anticipatory modal force term and the second corrective modal force term,

and wherein the device comprises

a means for calculating an anticipated longitudinal jerk () and a means for calculating an anticipated transverse jerk (),

the first means for calculating the first anticipatory modal force term being configured to calculate an anticipatory pitch modal torque (c<sub>φ

2ant</sub>) as a function of the anticipated longitudinal jerk () and an anticipatory roll modal torque (c<sub>θ

2ant</sub>) as a function of anticipated transverse jerk (), and

a means for measuring a brake master cylinder pressure,

the means for calculating the anticipated longitudinal jerk () being configured to calculate the anticipated longitudinal jerk () from the brake master cylinder pressure, an anticipated engine torque to the wheels, and the sprung mass (MSUS).

26. Suspension control device according to claim 25, wherein the means for calculating the anticipated longitudinal jerk () is configured to use a prerecorded table or curve that gives a master cylinder braking force as a function of the master cylinder pressure to retrieve the value (EFR) of this breaking force that corresponds to the master cylinder pressure (P_MC),

the means for calculating the anticipated longitudinal jerk () comprises a low-pass filter for the braking force (EFR), and a derivation circuit for the braking force (EFR) thus filtered in order to obtain the derivative Ė

_FRF of the filtered braking force (EFR),

the means for calculating the anticipated longitudinal jerk () is configured to calculate an anticipated engine force to the wheels (EMR), equal to the anticipated engine torque to the wheels (C_R) divided by a prerecorded mean wheel radius (Rmoy),

the means for calculating the anticipated longitudinal jerk () comprises a low-pass filter for this anticipated engine force (EMR) to the wheels, and a derivation circuit for the anticipated engine force (EMR) thus filtered in order to obtain the derivative Ė

_MRF of the filtered engine force (EMR),

the anticipated longitudinal jerk being equal to

27. Suspension control device according to claim 26, which comprises a means for measuring the vehicle speed (VVH), a means for calculating the engine rotation speed ω

_MOT at the vehicle speed (VVH) and a means for calculating the anticipated engine torque to the wheels C_R, using the formula;

C_R=C_M·

R_EMBR(i),

with R_EMBR(i)=ω

_MOT/ω

_ROUE

where R_EMBR(i) is the gear ratio having the number i, ω

_ROUE is the wheel rotation speed, C_M is a predetermined engine torque.

28. Suspension control device according to claim 23, wherein the means for calculating an anticipated transverse jerk () is configured to calculate the anticipated transverse jerk as a function of the sprung mass (MSUS), the front-rear mass distribution value (RMAvAr), the vehicle speed VVH, and the steering wheel rotation speed {dot over (δ

)}, using the formula;

29. Suspension control device according to claim 28, which comprises a wheel-to-body displacement sensor (CAP-DEB) at least for one wheel, a means for calculating the displacement speed (VDEB) of the damper from the displacement of the corresponding wheel, a means for calculating a setpoint force (FA1) for the damper (AM) as a function of said at least one modal setpoint force, and a means for calculating the control magnitude (ER) for the actuator (M) as a function of this setpoint force (FA1) and the wheel displacement speed (VDEB).

30. Production method for equipping a motor vehicle with the suspension control device according to claim 1, the motor vehicle being equipped with wheels, a body, a suspension having at least one damper with variable damping of the body on the wheels, said method comprising:

mounting a computer on the vehicle, and programming the computer using at least one program having program instructions that program the computer into the suspension control device.

31. Suspension control device according to claim 1, wherein the weighting coefficient (α

) is 0 by default and changes to 1 during a demand time, then changes back to 0 during a modulation time,

wherein the demand time is determined by detecting at least one of the following events;

rising edge for longitudinal driver demand,

rising edge for lateral driver demand,

longitudinal jerk crossing the threshold upon longitudinal driver demand,

longitudinal acceleration variation crossing the threshold upon longitudinal driver demand,

transverse jerk crossing the threshold upon transverse driver demand,

transverse acceleration variation crossing the threshold upon transverse driver demand.

32. Suspension control device according to claim 31, wherein the weighting coefficient (α

) is calculated as a function of

an anticipated longitudinal jerk ,

an anticipated transverse jerk ,

a corrected longitudinal acceleration {umlaut over (X)}_COR,

a corrected transverse acceleration Ÿ

_COR, and

a sportive mode information unit IS,

wherein

the anticipated longitudinal jerk is determined using the formula;