System and method for adaptive brake application and initial skid detection

• US 6,132,016 A
• Filed: 05/02/1997
• Issued: 10/17/2000
• Est. Priority Date: 05/02/1997
• Status: Expired due to Term

• Current Assignee: Hydro-Aire, Inc. (Crane Company)
• Original Assignee: Hydro-Aire, Inc. (Crane Company)
• Inventors: Cook, Robert D., Salamat, Bijan
• Primary Examiner(s): Graham, Matthew C.
• Application Number:
  US08/850,680
• Time in Patent Office: 1,264 Days
• Field of Search: 303/112, 303/135, 303/9.61, 303/187, 303/188, 303/189, 303/126, 303/178, 303/156, 188/181.2, 188/181 C, 188/181 A
• US Class Current: 303/178
• CPC Class Codes: B60T 13/662 characterised by specified functions of the control system components
• CPC Class Codes: B60T 2210/13 Aquaplaning, hydroplaning
• CPC Class Codes: B60T 8/1703 for aircrafts
• CPC Class Codes: B60T 8/17616 Microprocessor-based systems
• CPC Class Codes: B60T 8/325 Systems specially adapted for aircraft

Abstract

The adaptive brake application and initial skid detection system allows rapid brake application and prevents deep initial skids. Brake pressure is compared with a predetermined threshold brake pressure. Wheel velocity error signals are also generated to indicated the difference between the wheel velocity and a reference velocity signal. A pressure bias modulator integrator responsive to brake pressure signals adjusts the wheel velocity error signals to provide an anti-skid control signal. The pressure bias modulator integrator can also be initialized to the value of the measured brake pressure when the wheel velocity error signals indicate the beginning of a skid. Brake pressure difference signals are generated to indicate the difference between brake pressure and a commanded brake pressure, and an adjusted brake pressure error signal is generated in response to the brake pressure difference signals.

Claims

1. A method of detecting initial skidding and applying brake pressure for braking of a wheel of an aircraft during landing of the aircraft, the aircraft having a wheel brake for applying brake pressure to said wheel, the method comprising the steps of:

sensing brake pressure when brake pressure is applied and generating brake pressure signals that are a function of the braking pressure applied to the wheel brake;

comparing said brake pressure signals with a predetermined threshold brake pressure;

generating wheel speed signals that are a function of the rotational speed of the wheel;

generating a wheel velocity signal based upon said wheel speed signals;

generating a reference velocity signal;

comparing said wheel velocity signal with said reference velocity signal and generating wheel velocity error signals indicative of the difference between said wheel velocity signal and said reference velocity signal;

providing a pressure bias modulator integrator for controlling a maximum allowable brake pressure responsive to said brake pressure signals and said wheel velocity error signals to provide an anti-skid control signal;

initializing the pressure bias modulator integrator with the predetermined threshold brake pressure plus a predetermined constant pressure value, when the brake pressure reaches the predetermined threshold brake pressure; and

generating a command brake pressure signal in response to a deceleration command and said anti-skid control signal.

2. The method of claim 1, further comprising the step of initializing the pressure bias modulator integrator to the value of the brake pressure when the wheel velocity error signals indicate the beginning of a skid.

3. A method of detecting initial skidding and applying brake pressure for braking of a wheel of an aircraft during landing of the aircraft, the aircraft having a wheel brake for applying brake pressure to said wheel, the method comprising the steps of:

sensing brake pressure when brake pressure is applied, and generating brake pressure signals that are a function of the braking pressure applied to the wheel brake;

comparing said brake pressure signals with a predetermined threshold brake pressure;

generating wheel speed signals that are a function of the rotational speed of the wheel;

generating a wheel velocity signal based upon said wheel speed signals;

generating a reference velocity signal;

comparing said wheel velocity signal with said reference velocity signal and generating wheel velocity error signals indicative of the difference between said wheel velocity signal and said reference velocity signal;

providing a pressure bias modulator integrator for controlling a maximum allowable brake pressure responsive to said brake pressure signals and said wheel velocity error signals to provide an anti-skid control signal;

initializing the pressure bias modulator integrator when the brake pressure reaches the predetermined threshold brake pressure with the predetermined threshold brake pressure plus a predetermined constant pressure value, to thereby minimize delay of said pressure bias modulator integrator in controlling the maximum allowable brake pressure; and

generating a command brake pressure signal in response to a deceleration command and said anti-skid control signal.

4. The method of claim 3, further comprising the step of initializing the pressure bias modulator integrator to the value of the brake pressure when the wheel velocity error signal becomes greater than said reference velocity signal.

5. An adaptive brake application and initial skid detection system for braking of a wheel of a vehicle, comprising:

a wheel brake for applying brake pressure to the wheel;

a brake pressure sensor for generating brake pressure signals that are a function of the braking pressure applied to the wheel brake;

means for comparing said brake pressure signals with a predetermined threshold brake pressure;

wheel speed signal generating means for producing wheel speed signals that are a function of the rotational speed of the wheel;

a wheel velocity converter for generating a wheel velocity signal based upon said wheel speed signals;

velocity reference generating means for generating a reference velocity signal;

wheel velocity comparison means for comparing said wheel velocity signal with said reference velocity signal for generating wheel velocity error signals indicative of the difference between said aircraft wheel velocity signals and said reference velocity signal;

a pressure bias modulator integrator for controlling a maximum allowable brake pressure to provide an anti-skid control signal responsive to said brake pressure signals and said wheel velocity error signals;

means for initializing the pressure bias modulator integrator with the predetermined threshold brake pressure plus a predetermined constant pressure value, to thereby minimize delay of said pressure bias modulator integrator in controlling the maximum allowable brake pressure; and

command brake pressure signal generating means for generating a command brake pressure signal in response to a deceleration command and said anti-skid control signal.

6. The adaptive brake application and initial skid detection system of claim 5, further comprising means for initializing the pressure bias modulator integrator to the value of the measured brake pressure when the wheel velocity error signal becomes greater than said reference velocity signal.

7. An adaptive brake application and initial skid detection system for braking of a wheel of a vehicle, comprising:

a wheel brake for applying brake pressure to the wheel;

a brake pressure sensor for generating brake pressure signals that are a function of the braking pressure applied to the wheel brake;

means for comparing said brake pressure signals with a predetermined threshold brake pressure;

wheel speed signal generating means for producing wheel speed signals that are a function of the rotational speed of the wheel;

a wheel velocity converter for generating a wheel velocity signal based upon said wheel speed signals;

velocity reference generating means for generating a reference velocity signal;

wheel velocity comparison means for comparing said wheel velocity signal with said reference velocity signal for generating wheel velocity error signals indicative of the difference between said aircraft wheel velocity signals and said reference velocity signal;

a pressure bias modulator integrator for controlling a maximum allowable brake pressure to provide an anti-skid control signal responsive to said brake pressure signals and said wheel velocity error signals;

means for initializing the pressure bias modulator integrator with the predetermined threshold brake pressure plus a predetermined constant pressure value, to thereby minimize delay of said pressure bias modulator integrator in controlling the maximum allowable brake pressure;

means for initializing the pressure bias modulator integrator to the value of the measured brake pressure when the wheel velocity error signal becomes greater than said reference velocity signal; and

command brake pressure signal generating means for generating a command brake pressure signal in response to a deceleration command and said anti-skid control signal.