Process for correcting the rotational speeds of vehicle wheels determined by wheel sensors

• US 5,179,526 A
• Filed: 06/03/1991
• Issued: 01/12/1993
• Est. Priority Date: 06/22/1990
• Status: Expired due to Fees

• Current Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Original Assignee: Mercedes-Benz AG (Mercedes-Benz Group AG)
• Inventors: Klarer, Martin, Muller, Armin, Zimmer, Richard
• Primary Examiner(s): Chin, Gary
• Application Number:
  US07/709,308
• Time in Patent Office: 589 Days
• Field of Search: 364/426.02, 364/426.03, 364/565, 180/197, 303/95, 303/100, 303/102, 303/103, 303/105, 303/106, 324/160, 324/166
• US Class Current: 702/141
• CPC Class Codes: B60T 2240/08 Spare wheel detection; Adjusting brake control in case of spare wheel use
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: G01P 21/02 of speedometers
• CPC Class Codes: G01P 3/489 Digital circuits therefor
• CPC Class Codes: G01P 3/56 for comparing two speeds

Abstract

A method for correcting the rotational speeds of vehicle wheels determined by wheel sensors, a measurement of wheel speeds of the wheels of a vehicle being carried out, with specific driving conditions being that the vehicle is being neither accelerated nor braked and has no transverse acceleration. In a first part of the method, a matching of the measured wheel speeds is carried out under the specific driving conditions when the condition that the vehicle speed is below a first threshold value is satisfied. The matching of the measured wheel speeds is carried out by determining a matching factor for each of the two vehicle sides, so that, for example for the left vehicle side, matched wheel speeds are obtained from the measured wheel speeds. One of the matched wheel speeds of the left vehicle side is made equal to the associated measured wheel speed and the other of the two matched wheel speeds of the left vehicle side is obtained from the associated measured wheel by multiplying by the matchine factor of the left vehicle side, in such a way that the two matched wheel speeds of the left vehicle side assume the same value. In a second part of the method, the measured wheel speeds are balanced under the specific driving conditions when the condition that the vehicle speed is above a threshold value is satisfied. The balancing is carried out by determining a balancing factor for each wheel in relation to a reference wheel, in such a way that the balance wheel speed and the wheel speed of the reference wheel coincide with one another, and the measured wheel speeds are multiplied by the balancing factors determined in the second part of the method.

Claims

1. A method for correcting the rotational speeds of vehicle wheels determined by wheel sensors, comprising:

measuring wheel speeds of individual wheels of a vehicle;

determining balancing factors of the individual wheels under specific driving conditions, the specific driving conditions being that the vehicle is being neither accelerated nor braked and has no transverse acceleration;

in a first part of the method, matching the measured wheel speeds under the specific driving conditions and when the vehicle speed is below a first threshold value, the vehicle speed and the specific driving conditions being determined from the measured wheel speeds, the matching of the measured wheel speeds including the step of determining a matching factor for each of the two vehicle sides so that the matched wheel speeds are obtained from the measured wheel speeds that are associated with the matched wheel speeds;

one of the two matched wheel speeds of the left vehicle side being equal to its associated measured wheel speed, and the other of the two matched wheel speeds of the left vehicle side being obtained from its associated measured wheel speed by multiplying the matching factor of the left vehicle side, in such a way that the two matched wheel speeds of the left vehicle side have the same value;

one of the two matched wheel speeds of the right vehicle side being equal to its associated measured wheel speed and the other of the two matched wheel speeds of the right vehicle side being obtained from its associated measured wheel speed by multiplying the matching factor of the right vehicle side, in such a way that the two matched wheel speeds of the right vehicle side have the same value;

in a second part of the method, measuring the wheel speeds again to provide newly measured wheel speeds;

balancing the newly measured wheel speeds under the specific driving conditions and when the condition that the vehicle speed is above a second threshold value is satisfied, to thereby provide balanced wheel speeds;

determining from the newly measured wheel speeds, with the matching factors being taken into account, the vehicle speed and the specific driving conditions;

wherein the step of balancing includes fixing one of the individual vehicle wheels as a reference wheel and determining a balancing factor for each individual vehicle wheel in relation to said reference wheel, in such a way that the balanced wheel speed coincides with the wheel speed of the reference wheel, and

correcting measurements of wheel speeds measured after the balancing step by multiplying the wheel speeds measured after the balancing step by the corresponding determined balancing factors.

2. The method of claim 1, further including the step of updating the balancing factors at specific time intervals.

3. The method of claim 1, further including the step of updating the balancing factors according to a specific distance covered by the vehicle.

4. The method of claim 3, further including determining a criterion for the updating of the balancing factors by taking weighted account of the time interval between the last updating of the balancing factors and the distance covered by the vehicle after said last update.

5. The method of claim 1, wherein the specific driving conditions that the vehicle is being neither accelerated nor braked is derived in the first part of the method when a wheel acceleration or wheel accelerations formed from the measured wheel speed or measured wheel speeds are below a third threshold value.

6. The method of claim 1, wherein the specific driving conditions that the vehicle is being neither accelerated nor braked is derived in the first part of the method when the amount of the difference between the average value of the wheel speeds of the front axle and the average value of the wheel speeds of the rear axle is below a third threshold value.

7. The method of claim 1, wherein the specific driving condition that the vehicle has no transverse acceleration is derived in the first part of the method when the amount of the difference between the average value of the wheel speeds of the front axle and the average value of the wheel speeds of the rear axle is below a third threshold value.

8. The method of claim 1, wherein the specific driving condition that the vehicle has no transverse acceleration is derived in the first part of the method when the amount of the difference between wheel speeds of wheels, which are mounted on different vehicle sides on the same axle, falls below a third threshold value.

9. The method of claim 1, wherein the specific driving conditions that the vehicle is being neither accelerated nor braked is derived in the second part of the method when a wheel acceleration or wheel accelerations formed from at least one of the matched wheel speeds are below a third threshold value.

10. The method of claim 1, wherein the specific driving conditions that the vehicle is being neither accelerated nor braked is derived in the second part of the method when the amount of the difference between the average value of the wheel speeds of the front axle and the average value of the wheel speeds of the rear axle is below a third threshold value.

11. The method of claim 1, wherein the specific driving condition that the vehicle has no transverse acceleration is derived in the second part of the method when the amount of the difference between the average value of the wheel speeds of the front axle and the average value of the wheel speeds of the rear axle is below a third threshold value.

12. The method of claim 1, wherein the specific driving condition that the vehicle has no transverse acceleration is derived in the second part of the method when the amount of the difference between matched wheel speeds of wheels, which are mounted on different vehicle sides on the same axle, falls below a third threshold value.

13. The method of claim 1, wherein the specific driving conditions that the vehicle is being neither accelerated nor braked is derived in at least one of the first and second parts of the method from control signals of at least one of an anti-lock system and a drive-slip control system.

14. The method of claim 2, further including determining a criterion for the updating of the balancing factors by taking weighted account of the time interval between the last updating of the balancing factors and the distance covered by the vehicle after said last update.