METHOD AND SYSTEM FOR DIAGNOSING THE CONDITION OF A MOTOR VEHICLE TYRES

• US 20090118894A1
• Filed: 09/11/2006
• Published: 05/07/2009
• Est. Priority Date: 09/16/2005
• Status: Abandoned Application

• Current Assignee: Peugeot Citroen Automobiles SA (Stellantis NV)
• Original Assignee: Peugeot Citroen Automobiles SA (Stellantis NV)
• Inventors: Djama, Zahir, Le Bret, Denis
• Application Number:
  US12/067,172
• Publication Number:
  US 20090118894A1
• Time in Patent Office: Days
• US Class Current: 701/29
• CPC Class Codes: B60C 23/06 Signalling devices actuated by deformation of the tyre , e.g. tyre mounted deformation sensors or indirect determination of tyre deformation based on wheel speed, wheel-centre to ground distance or inclination of wheel axle

Abstract

The invention concerns a method for diagnosing the condition of tires of a front wheel and of a rear wheel of a motor vehicle arranged on the same side of the vehicle and connected to the body shell thereof via suspension means. Said method includes a step (102) of acquiring the vertical acceleration of said wheels in a reference model of the vehicle, a step (104) of time-based resetting of one of the acquired accelerations on the other of the acquired accelerations, a step (112) of estimating the coefficients of stiffness of the tires based on the thus temporally reset accelerations, and a step (120) of determining the condition of the tires based on the estimated coefficients of stiffness.

Claims

1. Method of diagnosing the state of tires of a front wheel and of a rear wheel of a motor vehicle arranged on a same side of the vehicle and connected to the body thereof by means of suspensions, the method including a step of acquiring the vertical accelerations of said wheels in a referential of the vehicle, wherein said method comprises:

a step of temporally resetting one of the acquired accelerations on the other of the acquired accelerations;

a step of estimating coefficients of stiffness of the tires as a function of the thus temporally reset accelerations; and

a step of determining the state of the tires as a function of the estimated coefficients of stiffness.

2. Method according to claim 1, wherein the temporally resetting step comprises a step of calculating the inter-correlation between the acquired accelerations and a step of applying a delay corresponding to the maximum of the calculated inter-correlation to the acquired acceleration of the front wheel.

3. Method according to claim 1, wherein the coefficient of stiffness estimating step is adapted to estimate these coefficients of stiffness from mono-wheel mechanical models of said wheels connected to the body of the vehicle by means of the suspensions.

4. Method according to claim 3, wherein the coefficient of stiffness estimating step is adapted to estimate these coefficients of stiffness based on a model in discrete time of the reset accelerations of said wheels according to the equation:

$\mathrm{Avr}<br><br>\left(k\right)=\frac{1}{\mathrm{mrr}}<br><br>\left(\mathrm{mra}\times <br><br>\mathrm{Ava}<br><br>\left(k-n\right)<br><br><br><br>\mathrm{Zva}<br><br>\left(k-n\right)-\mathrm{Zvr}<br><br>\left(k\right)\right)<br><br>\left(\begin{array}{c}\mathrm{Kpr}<br><br>\left(k\right)/\mathrm{Kpa}<br><br>\left(k\right)\\ \mathrm{Kpr}<br><br>\left(k\right)\end{array}\right)$

where k is the k^th sampling instant, mrr and mra are the masses of the rear and front wheel, respectively, Avr and Ava are the vertical accelerations of the rear and front wheels, respectively, Zvr and Zva are the altitudes of the centers of the rear and front wheels, respectively, in the referential of the vehicle, Kpr and Kpa are the coefficients of stiffness of the tires of the rear and front wheels, respectively, and n is a resetting instant corresponding to a temporal delay between the rear and front wheel subjected to the same portion of the roadway.

5. Method according to claim 3, wherein the estimating step is adapted to estimate said coefficients of stiffness based on a model in discrete time of the reset accelerations of the front and rear wheels according to the equation:

$\mathrm{Ava}<br><br>\left(k\right)=\frac{1}{\mathrm{mra}}<br><br>\left(\mathrm{mrr}\times <br><br>\mathrm{Avr}<br><br>\left(k+n\right)<br><br><br><br>\mathrm{Zvr}<br><br>\left(k+n\right)-\mathrm{Zva}<br><br>\left(k\right)\right)<br><br>\left(\begin{array}{c}\mathrm{Kpa}<br><br>\left(k\right)/\mathrm{Kpr}<br><br>\left(k\right)\\ \mathrm{Kpa}<br><br>\left(k\right)\end{array}\right)$

where k is the k^th sampling instant, mrr and mra are the masses of the rear and front wheel, respectively, Avr and Ava are the vertical accelerations of the rear and front wheels, respectively, Zvr and Zva are the altitudes of the centers of the rear and front wheels, respectively, in the referential of the vehicle, Kpr and Kpa are the coefficients of stiffness of the tires of the rear and front wheels, respectively, and n is a resetting instant corresponding to a temporal delay between the rear and front wheel subjected to the same portion of the roadway.

6. Method according to claim 1, wherein the estimating step is adapted to estimate said coefficients of stiffness from a bicycle mechanical model of the body assimilated to a mass connected to the front and rear wheels by means of the suspensions.

7. Method according to claim 5, wherein the estimating step is adapted to estimate said coefficients of stiffness based on a model in discrete time of the reset accelerations of the front and rear wheels according to the equation:

$\mathrm{Avr}<br><br>\left(k\right)={\left(\begin{array}{c}\frac{\mathrm{mra}}{\mathrm{mrr}}<br><br>\mathrm{Ava}<br><br>\left(k-n\right)\\ \frac{1}{\mathrm{mrr}}<br><br>\left(\mathrm{Zva}<br><br>\left(k-n\right)-\mathrm{Zvr}<br><br>\left(k\right)\right)\\ \frac{1}{\mathrm{mnr}}<br><br>\stackrel{.}{Z}<br><br>\mathrm{va}<br><br>\left(k-n\right)\\ -\frac{1}{\mathrm{mrr}}<br><br>\stackrel{.}{Z}<br><br>\mathrm{vr}<br><br>\left(k\right)\end{array}\right)}^T<br><br>\left(\begin{array}{c}\mathrm{Kpr}<br><br>\left(k\right)/\mathrm{Kpa}<br><br>\left(k\right)\\ \mathrm{Kpr}<br><br>\left(k\right)\\ \left(\mathrm{Kpr}<br><br>\left(k\right)/\mathrm{Kpa}<br><br>\left(k\right)\right)\times <br><br>\mathrm{Kca}<br><br>\left(k\right)\\ \mathrm{Kcr}<br><br>\left(k\right)\end{array}\right)$

Where k is the kth sampling instant, mrr and mra are the masses of the rear and front wheel, respectively, Avr and Ava are the vertical accelerations of the rear and front wheels, respectively, Zvr and Zva are the altitudes of the centers of the rear and front wheels, respectively, in the referential of the vehicle, Kpr and Kpa are the coefficients of stiffness of the tires of the rear and front wheels, respectively, n is a resetting instant corresponding to a temporal delay between the rear and front wheel subjected to the same portion of the roadway, Kca and Kcr are coefficients of stiffness of the suspensions of the front and rear wheels, respectively, and Ż

va et Ż

vr are the speeds of the centers of the front and rear wheels, respectively.

8. Method according to claim 1, wherein the coefficient of stiffness estimating step is adapted to implement a recursive least square algorithm in real time.

9. Method according to claim 1, wherein the tire state determining step comprises, for each tire, a step of comparing its determined coefficient of stiffness to a predetermined threshold value and a step of diagnosing the state of the tire adapted to determine that this tire is defective if its determined coefficient of stiffness is higher than the threshold value.

10. System for diagnosing the state of tires of a front wheel and of a rear wheel of a motor vehicle arranged on a same side of the vehicle and connected to the body thereof by means of suspensions, the system including means for acquiring the vertical accelerations of said wheels in a referential of the vehicle, wherein said system comprises:

means for temporally resetting one of the acquired accelerations based on the other acquired acceleration;

means for estimating coefficients of stiffness of the tires as a function of the thus temporally reset accelerations; and

means for determining the state of the tires as a function of the estimated coefficients of stiffness,

said means being adapted to implement the method according to claim 1.