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

• US 8,190,327 B2
• Filed: 09/13/2006
• Issued: 05/29/2012
• Est. Priority Date: 09/22/2005
• Status: Expired due to Fees

• Current Assignee: Peugeot Citroen Automobiles SA (Stellantis NV)
• Original Assignee: Peugeot Citroen Automobiles SA (Stellantis NV)
• Inventors: Poilbout, Francois
• Primary Examiner(s): Dickson, Paul N
• Assistant Examiner(s): ENGLISH, JAMES A
• Application Number:
  US12/067,763
• Publication Number:
  US 20080319609A1
• Time in Patent Office: 2,085 Days
• Field of Search: 701/37, 701/38, 280 55- 5509
• US Class Current: 701/37
• 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 17/01933 Velocity, e.g. relative velocity-displacement sensors
• CPC Class Codes: B60G 2400/0521 Roll rate
• CPC Class Codes: B60G 2400/0522 Pitch rate
• CPC Class Codes: B60G 2400/0531 Roll acceleration
• CPC Class Codes: B60G 2400/0532 Pitch acceleration
• 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 2400/252 vertical
• CPC Class Codes: B60G 2500/10 Damping action or damper
• CPC Class Codes: B60G 2800/91 Suspension Control
• CPC Class Codes: B60G 2800/912 Attitude Control; levelling control
• CPC Class Codes: B60G 3/04 the arm being essentially transverse to the longitudinal axis of the vehicle
• CPC Class Codes: B60G 3/20 all arms being rigid

Abstract

The invention relates to a device for controlling the suspension of the body shell of a motor vehicle. The inventive device comprises a calculator (CSS) which can calculate a control value (ER) for an actuator (M) of a shock absorber (AM) of the suspension (S) as a function of at least one modal body shell speed calculated from a modal body shell acceleration. The invention is characterized by a sensor (CAP-DEB) for sensing wheel (A,B, C, D) travel in relation to the body shell, which is connected to a first means (CAL) for calculating the modal body shell acceleration from the travel measurement (DEB) provided by the sensor (CAP-DEB).

Claims

1. Suspension control device with variable damping for a motor vehicle body on its wheels, said device comprising:

a computer adapted to calculate a control magnitude of an actuator of at least one damper with variable damping of a suspension of the vehicle as a function of at least one body modal speed, calculated from at least one body modal acceleration determined on the vehicle,

at least one displacement sensor providing a displacement measurement which is a measurement of a displacement of a wheel of the vehicle with respect to the vehicle body,

a first calculation means for calculating the body modal acceleration from the displacement measurement provided by the displacement sensor, wherein the first calculation means for calculating the body modal acceleration comprises;

a suspension force estimator providing an estimation of at least one force exerted by a suspension of said wheel on the body as a function of at least the displacement measurement provided by the displacement sensor, and

a second calculation means for calculating the body modal acceleration as a function of at least the suspension force provided by said suspension force estimator.

2. Control device according to claim 1, wherein the suspension force estimator comprises:

a derivator module calculating a displacement speed from the displacement measurement provided by the displacement sensor,

a damping force estimator providing an estimation of a damping force of the damper as a function of the displacement speed provided by the derivator module and a memorized current damping law of the damper,

a dry friction force estimator providing an estimation of a dry friction force as a function of the displacement speed,

a flexion force estimator providing an estimation of a flexion force of suspension springs and stops of the damper as a function of the displacement value and a determined static attitude of the body.

3. Control device according to claim 2, wherein the dry friction force estimator provides the estimation of the dry friction force as a hyperbolic tangential or circular tangent function of the displacement speed divided by a fixed value, this function being multiplied by a prescribed multiplying factor.

4. Control device according to claim 2, wherein the flexion force estimator comprises:

a static attitude calculation module for calculating the static attitude of the vehicle as a function of the displacement value,

an adder for calculating a summed value of the displacement value and the static attitude,

an absolute flexion force calculation module for calculating an absolute flexion force of suspension springs and stops of the damper as a function of said summed value,

a static flexion force calculation module for calculating a static flexion force on said wheel as a function of the static attitude,

a subtractor providing said flexion force of suspension springs and stops by subtracting the static flexion force from the absolute flexion force of suspension springs and stops.

5. Suspension control device according to claim 4, wherein a displacement sensor is provided for each of the two front wheels and the two rear wheels, and the static attitude calculation module has a means for calculating the front static attitude and the rear static attitude of the vehicle, as being the mean displacement of the front wheel displacements and the rear wheel displacements, respectively, filtrated by a low-pass filter, a front attitude offset constant and a rear attitude offset constant, respectively, being added to this filtered mean displacement.

6. Control device according to claim 1, wherein the first calculation means further comprises a roll torque estimator providing an estimation of a roll torque and/or an estimator of a pitch torque.

7. Control device according to claim 6, wherein the first calculation means has:

a means for calculating a transverse acceleration reset value RECT,

a sensor of the vehicle body transverse acceleration ACCT;

the roll torque estimator calculating said roll torque c_θ

using the formula;

c_θ

=(ACCT−

RECT)·

(MTOT)·

d(G,CR)

where MTOT is the vehicle mass, and

d(G, CR) is the predetermined distance between the center of gravity (G) of the body and its roll center (CR).

8. Control device according to claim 6, wherein the first calculation means has:

a means for calculating a longitudinal acceleration reset value RECL,

a sensor of the longitudinal acceleration ACCL of the vehicle body,

the estimator of the pitch torque calculating said pitch torque c_φ

using the formula;

c_φ

=(ACCL−

RECL)·

(MTOT)·

hG+c<sub>φ

B</sub>,

where MTOT is the vehicle mass,

hG is the predetermined height between the center of gravity (G) of the body and its pitch center (CT), and

c<sub>φ

B</sub> is the component of the pitch torque attributable to the Brouilhet effect.

9. Control device according to claim 8, wherein the component c_φ

B of the pitch torque attributable to the Brouilhet effect is calculated as a function of a braking information unit provided by a determination module as a function of a master cylinder pressure value provided by a master cylinder pressure sensor.

10. Control device according to claim 1, which comprises a body modal acceleration filter that eliminates at least the low frequencies of the body modal acceleration provided by the first calculation means and a third means for calculating the body modal velocity from the filtered body modal acceleration provided by the first filter.

11. Control device according to claim 10, wherein the low cutoff frequency of the body modal acceleration filter is greater than or equal to 0.1 Hz.

12. Control device according to claim 1, wherein the first means for calculating the body modal acceleration comprises a displacement measurement filter that eliminates at least the low frequencies from the displacement measurement provided by the displacement sensor.

13. Control device according to claim 12, wherein the low cutoff frequency of the displacement measurement filter is greater than or equal to 0.2 Hz.

14. Control device according to claim 1, wherein the control magnitude is a damping law determined from a plurality of different damping laws that impose the damper force as a function of its displacement speed.

15. Motor vehicle having a body, wheels, a suspension of the body on the wheels, and a suspension control device according to claim 1.

16. Production method for equipping a motor vehicle,

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:

providing the suspension control device according to claim 1,

mounting the computer on the vehicle, and

programming the computer using at least one program having program instructions that employ the calculating means of the suspension control device according to claim 1.

17. Computer-readable medium carrying a computer program for controlling a computer, having program instructions for calculating a body modal acceleration from a displacement measurement provided by a wheel displacement sensor of a wheel of a vehicle body, for calculating a body modal velocity as a function of at least this body modal acceleration, and for calculating a control magnitude of an actuator of a damper of a suspension of the wheel as a function of this body modal speed, when it is employed in a suspension control device according to claim 1,

wherein the computer program comprises:

a suspension force estimator providing an estimation of at least one force exerted by a suspension of the wheel as a function of at least the displacement measurement provided by the displacement sensor, and

a calculation means for calculating the body modal acceleration as a function of at least a suspension force provided by the suspension force estimator.

18. Computer-readable medium according to claim 17, wherein the suspension force estimator comprises:

a derivator module calculating a displacement speed from the displacement measurement provided by the displacement sensor,

a damping force estimator providing an estimation of a damping force of the damper as a function of the displacement speed provided by the derivator module and a memorized current damping law of the damper,

a dry friction force estimator providing an estimation of a dry friction force as a function of the displacement speed,

a flexion force estimator providing an estimation of a flexion force of suspension springs and stops of the damper as a function of the displacement value and a determined static attitude of the body.