Methods of learning long term brake corner specific torque variation

Patent metadata

Field	Value
Publication number	US-2018201243-A1
Application number	US-201715410598-A
Country	US
Kind code	A1
Filing date	Jan 19, 2017
Priority date	Jan 19, 2017
Publication date	Jul 19, 2018
Grant date	—

Abstract

Systems and methods are provided for controlling a vehicle using a specific torque of a brake system. In one embodiment, a method of using a specific torque of a brake system for a vehicle includes: determining a brake pressure of the brake system during a braking operation; determining a deceleration of the vehicle during the braking operation; determining a vehicle mass and a wheel radius; estimating a specific torque of the brake system based on the brake pressure and the deceleration; and operating the vehicle based on the specific torque.

First claim

What is claimed is:

1 . A method of using a specific torque of a brake system for a vehicle, the method comprising:
determining a brake pressure of the brake system during a braking operation; determining a deceleration of the vehicle during the braking operation; determining a vehicle mass and a wheel radius of the vehicle; estimating a specific torque of the brake system based on the brake pressure, the vehicle mass, the wheel radius, and the deceleration; and operating the vehicle based on the specific torque.

2 . The method of claim 1 , further comprising determining whether the braking operation is a qualifying brake application that is suitable for learning the specific torque, and wherein estimating the specific torque is in response to determining that the braking operation is the qualifying brake application.

3 . The method of claim 2 , wherein determining whether the braking operation is a qualifying brake operation is based on a vehicle mass, a road grade, a rain status, a road surface coefficient, a brake burnish status, and a rate of change of the deceleration.

4 . The method of claim 1 , further comprising resetting the specific torque to an initial specific torque value in response to receiving a service reset request indicating a change of hardware in the brake system.

5 . The method of claim 1 , wherein estimating the specific torque includes estimating the specific torque as:

Specific



Torque

=

Vehicle



Mass
*
Deceleration
*
Tire



Radius

Brake



Pressure

6 . The method of claim 1 , further comprising storing the specific torque based on a brake temperature and an ambient humidity during the braking operation.

7 . The method of claim 6 , wherein storing the specific torque includes storing the specific torque in a three dimensional lookup table.

8 . The method of claim 6 , wherein storing the specific torque includes storing the specific torque as a deviation percent from an initial specific torque value.

9 . The method of claim 8 , wherein storing the specific torque is in response to determining that the specific torque is within a threshold percent of the initial specific torque value.

10 . The method of claim 1 , further comprising:
comparing the specific torque to a fault threshold; and indicating a brake system fault in response to the specific torque extending beyond the fault threshold.

11 . The method of claim 1 , wherein the brake pressure is a hydraulic brake pressure.

12 . A vehicle system for controlling a vehicle with a brake system, the vehicle system comprising:
a sensor system configured for determining a vehicle mass, a wheel radius, and a deceleration of the vehicle during the braking operation; a brake pressure module configured for determining a brake pressure of the brake system during a braking operation; a torque estimation module for estimating a specific torque of the brake system based on the vehicle mass, the wheel radius, the brake pressure, and the deceleration; and a brake system for operating the vehicle based on the specific torque.

13 . The vehicle system of claim 12 , further comprising:
a qualifying brake apply module configured for determining whether the braking operation is a qualifying brake application that is suitable for learning the specific torque, and wherein the torque estimation module is configured for estimating the specific torque in response to determining that the braking operation is the qualifying brake application.

14 . The vehicle system of claim 13 , wherein the qualifying brake apply module is configured for determining whether the braking operation is a qualifying brake operation based on a vehicle mass, a road grade, a rain status, a road surface coefficient, a brake burnish status, and a rate of change of the deceleration.

15 . The vehicle system of claim 12 , further comprising a service reset module for resetting the specific torque to an initial specific torque value in response to receiving a service reset request indicating a change of hardware in the brake system.

16 . The vehicle system of claim 12 , wherein the torque estimation module is configured for estimating the specific torque as:

Specific



Torque

=

Vehicle



Mass
*
Deceleration
*
Tire



Radius

Brake



Pressure

17 . The vehicle system of claim 12 , wherein the torque estimation module is configured for storing the specific torque based on a brake temperature and an ambient humidity during the braking operation.

18 . The vehicle system of claim 17 , wherein storing the specific torque is in response to determining that the specific torque is within a threshold percent of the initial specific torque value.

19 . The vehicle system of claim 12 , wherein the torque estimation module is configured for storing the specific torque as a deviation percent from an initial specific torque value.

20 . A vehicle, comprising:
a sensor system configured for determining a vehicle mass, a wheel radius, and a deceleration of the vehicle during the braking operation; a control system comprising:
a brake pressure module configured for determining a brake pressure of the brake system during a braking operation;
a torque estimation module for estimating a specific torque of the brake system based on the vehicle mass, the wheel radius, the brake pressure, and the deceleration; and
a brake system for operating the vehicle based on the specific torque.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Pennala Brandon C
• Krueger Eric E
• Monsere Patrick J
• Heil Edward T
• Nisonger Robert L
• Shami Constandi J
• Houtman Alan J

Classifications

• B60T8/172 Primary

  Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters {(B60T8/17551 takes precedence)} · CPC title

• B60T8/321 Primary

  deceleration (B60T8/34, B60T8/52, B60T8/54, B60T8/56, B60T8/58, B60T8/72, B60T8/86, B60T8/88 take precedence) · CPC title

• B60T17/22

  Devices for monitoring or checking brake systems; Signal devices · CPC title

• B60T8/1701

  Braking or traction control means specially adapted for particular types of vehicles (for vehicles having more than one drive axle B60T8/1769) · CPC title

• B60T8/18

  responsive to vehicle weight or load, e.g. load distribution ({using electrical circuitry on regulation means B60T8/17; } B60T8/30 takes precedence; responsive to weight and speed condition B60T8/58) · CPC title