Brake system providing limited antiskid control during a backup mode of operation

Patent metadata

Field	Value
Publication number	US-11273909-B2
Application number	US-201916451858-A
Country	US
Kind code	B2
Filing date	Jun 25, 2019
Priority date	Jun 25, 2019
Publication date	Mar 15, 2022
Grant date	Mar 15, 2022

Abstract

A brake system for a vehicle is disclosed and includes an energy storage device configured to store and discharge energy, a plurality of wheels, one or more processors operatively coupled to the energy storage device, and a memory coupled to the one or more processors. The memory stores data comprising a database and program code that, when executed by the one or more processors, causes the brake system to determine the brake system is operating in a backup mode of operation. In response to determining the brake system is operating in the backup mode of operation, the brake system calculates a dynamic slip of the plurality of wheels. The brake system is caused to determine a slip error by comparing the dynamic slip with a target slip value of the plurality of wheels. The brake system is also caused to calculate an antiskid command based on the slip error.

First claim

What is claimed is:

1. A brake system for a vehicle, wherein the brake system includes an energy storage device configured to store and discharge energy and a plurality of wheels, the brake system comprising:
one or more processors operatively coupled to the energy storage device and in electrical communication with the plurality of wheels; and
a memory coupled to the one or more processors, the memory storing data comprising a database and program code that, when executed by the one or more processors, causes the brake system to:
determine the brake system is operating in a backup mode of operation;
in response to determining the brake system is operating in the backup mode of operation, calculate a dynamic slip of the plurality of wheels;
determine a slip error by comparing the dynamic slip with a target slip value of the plurality of wheels, wherein the target slip value is offset from an ideal slip value of the plurality of wheels, results in a reduced braking efficiency of the brake system, is a fixed value based on a type of tire installed on the plurality of wheels, and is saved in the memory of the one or more processors;
select the target slip value resulting in the brake system having the vehicle come to a stop within a threshold time and a threshold distance; and
calculate an antiskid command based on the slip error, wherein the antiskid command reduces an amount of brake pressure applied to the plurality of wheels.

2. The brake system of claim 1 , wherein the one or more processors execute instructions to:
determine the slip error based on a wheel frequency of the plurality of wheels and an actual speed of the vehicle.

3. The brake system of claim 2 , wherein the one or more processors execute instructions to determine the slip error based on:

Dynamic
⁢

⁢
slip

=

(

actual
⁢

⁢
speed
⁢

⁢
signal

-

R
*
ω

)

actual
⁢

⁢
speed
⁢

⁢
signal

wherein R represents a tire rolling radius of the plurality of wheels of the vehicle and ω represents the wheel frequency of the plurality of wheels.

4. The brake system of claim 1 , wherein the one or more processors execute instructions to:
determine a proportional value by combining the slip error with a proportional gain, wherein combining the proportional gain with the slip error results in a proportional increase in a value of the antiskid command as the slip error remains constant.

5. The brake system of claim 4 , wherein the one or more processors execute instructions to:
determine a first integral value by combing the slip error with an integral gain value; and
integrate the first integral value, which results in a second integral value.

6. The brake system of claim 5 , wherein the one or more processors execute instructions to:
determine the antiskid command by combining the proportional value with the second integral value.

7. The brake system of claim 1 , wherein the one or more processors execute instructions to:
determine a brake pressure command based on a difference between the antiskid command and an input command, wherein the input command represents an amount of braking requested by the brake system.

8. The brake system of claim 1 , wherein the energy storage device is an accumulator, a battery, a capacitor, or a flywheel.

9. The brake system of claim 1 , wherein the type of tire depends on characteristics including belt construction and sidewall construction, and wherein the belt construction refers to either a radial or cross-ply construction.

10. An aircraft, comprising:
a brake system including a plurality of wheels and an accumulator, wherein the accumulator is configured to store and discharge fluid energy as a pressurized hydraulic brake fluid;
one or more processors operatively coupled to the accumulator and in electrical communication with the plurality of wheels; and
a memory coupled to the one or more processors, the memory storing data comprising a database and program code that, when executed by the one or more processors, causes the brake system to:
determine the brake system is operating in a backup mode of operation, wherein the backup mode of operation conserves the fluid energy stored in the accumulator;
in response to determining the brake system is operating in the backup mode of operation, calculate a dynamic slip of the plurality of wheels;
determine a slip error by comparing the dynamic slip with a target slip value of the plurality of wheels, wherein the target slip value is offset from an ideal slip value of the plurality of wheels, results in a reduced braking efficiency of the brake system, is a fixed value based on a type of tire installed on the plurality of wheels, and is saved in the memory of the one or more processors;
select the target slip value resulting in the brake system having the aircraft come to a stop within a threshold time and a threshold distance; and
calculate an antiskid command based on the slip error, wherein the antiskid command reduces an amount of brake pressure applied to the plurality of wheels.

11. The aircraft of claim 10 , wherein the one or more processors execute instructions to:
determine the slip error based on a wheel frequency of the plurality of wheels and an actual speed of the aircraft.

12. The aircraft of claim 11 , wherein the one or more processors execute instructions to determine the slip error based on:

Dynamic
⁢

⁢
slip

=

(

actual
⁢

⁢
speed
⁢

⁢
signal

-

R
*
ω

)

actual
⁢

⁢
speed
⁢

Assignees

• Boeing Co

Inventors

• Forghani Nima
• Yamamoto David T
• Smith Steven Elliot

Classifications

• B64C25/46 Primary

  Brake regulators for preventing skidding or aircraft somersaulting · CPC title

• B60T8/1703 Primary

  for aircrafts · CPC title

• B60T8/325

  Systems specially adapted for aircraft · CPC title

• B60T8/176

  Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS (B60T8/1755 takes precedence) · CPC title

• B60T13/66

  Electrical control in fluid-pressure brake systems · CPC title