Automatic aircraft braking system including wheelspeed responsive control apparatus

An automatic braking system for an aircraft comprising in combination:

• wheelspeed logic circuits for generating a wheelspeed logic output control signal when a pair of wheels disposed on opposite sides of the aircraft are turning at a combined wheelspeed exceeding a predetermined value;
• AND circuit means have a plurality of input terminals and an output terminal;
• means for coupling said wheelspeed logic output control signals to a first of said plurality of input terminals;
• braking switching means coupled to a second of said plurality of input terminals;
• throttle switching means coupled to a third of said plurality of input terminals;
• antiskid valve means;
• automatic brake modulator means coupled to the output of said AND circuit to provide automatic brake control signals;
• antiskid control circuit means for generating antiskid control signals;
• and
• means for coupling said automatic brake control signals and said antiskid control signals to said antiskid valve means.

The method of braking a first wheel on a first side of a plane passing through the fuselage of an aircraft and a second wheel on the remaining side of said plane comprising the following steps:

• measuring the wheelspeeds of said first and second wheels;
• applying a constant braking pressure to said first and second wheels for a first predetermined period of time after said wheelspeeds of said first and second wheels exceed a predetermined wheelspeed value;
• applying braking pressure subsequent to said first predetermined time period at an increasing rate of said first and second wheels until the rate of deceleration of said aircraft equals a predetermined rate of deceleration;
• and,
• adjusting braking pressure to said first and second wheels to maintain constant said predetermined rate of deceleration of said aircraft.

An automatic braking system for an aircraft comprising in combination:

• wheelspeed logic circuits for generating a wheelspeed logic output signal when a pair of wheels disposed on opposite sides of the aircraft are turning at a wheelspeed exceeding a predetermined value;
• AND circuit means having a plurality of input terminals and an output terminal;
• means for coupling said wheelspeed logic output control signals to a first of said plurality of input terminals;
• brake switching means coupled to a second of said plurality of input terminals;
• valve means;
• automatic brake modulator means coupled to the output of said AND circuit to provide automatic brake control signals;
• antiskid control circuit means for generating antiskid control signal;
• and
• means for coupling said automatic brake control signals and said antiskid control signals to said valve means.

A brake control system for applying and controlling a brake application means for a wheel of a vehicle independently of operator brake application comprising:

• signal generating means for producing a first signal that is related to the rotational speed of said wheel;
• reference generating means for generating a reference signal;
• rate selector means for manually selecting said reference signal indicative of a desired rate of vehicle deceleration;
• comparison means for comparing said first signal with said reference signal for generating an error signal indicative of the difference between said first signal and said reference signal;
• and
• control means for providing a signal to said brake application means to apply brake pressure to said wheel independently of operator brake application and responsive to said error signal to provide a selected deceleration brake control signal for controlling said brake pressure in order to maintain said desired rate of deceleration.

In combination in an automatic brake control system including brake application means responsive to a control signal to brake a wheel of a vehicle:

• first means for generating a first signal proportional to the the rate of deceleration of the wheel;
• second means for generating a second signal representative of a desired rate of deceleration of the wheel;
• an integrator circuit having an input, and output, and including capacitive feedback means coupled between said input and said output;
• an automatic brake logic circuit for providing an autobrake turn-on signal when automatic braking is to be initiated;
• on-ramp control circuit means providing an on-ramp signal having a relatively short duration in response to each said autobrake turn-on signal;
• means combining said first, said second and said on-ramp signals at said input of said integrator means whereby said capacitive feedback means is initially charged by said on-ramp signal to provide a control signal at said output of said integrator means which commands a low brake pressure, and is thereafter discharged at a rate dependent on the difference between said first and said second signals to provide a control signal which commands an increasing brake pressure up to a brake pressure representative of the difference between said first and said second signals;
• and
• means coupling said control signal to the brake application means.

In combination in an automatic brake control system including brake application means responsive to a control signal to brake a wheel of a vehicle:

• first means for generating a first signal proportional to the rate of deceleration of the wheel;
• second means for generating a second signal representative of a desired rate of deceleration of the wheel;
• an integrator circuit having an input, an output, and including capacitive feedback means coupled between said input and said output;
• a pilot-controlled switching means providing an autobrake turn-off signal when said automatic braking is to be terminated;
• off-ramp control circuit means providing an off-ramp signal in response to each said autobrake turn-off signal;
• means combining said first signal, said second signal, and said off-ramp signal at the input of said integrator whereby said integrator normally provides a control signal at said output which commands a brake pressure representative of the difference between said first and said second signals, and whereby said off-ramp signal is sufficiently large with respect to the difference between said first and said second signals to charge said capacitive feedback means to provide a control signal at said output of said integrator which commands a decreasing brake pressure from the value representative of the difference between said first and said second signals down to a low brake pressure.

In combination in an automatic wheel brake control system for an aircraft:

• means for generating signals representative of wheelspeed;
• wheelspeed logic means connected to said means for generating signals representative of wheelspeed for providing a first signal when said wheel has spun-up from substantially zero to a predetermined wheelspeed;
• pilot-controlled logic means for providing a second signal when automatic braking is to be initiated;
• an automatic braking logic circuit for providing an autobrake turn-on signal only upon the concurrence of said first and said second signals;
• valve means for controlling brake pressure application;
• and
• means coupled between said means for generating signals representative of wheelspeed and said valve means, for generating brake control signals to increase brake pressure and decelerate the wheel to one of a plurality of manually selectable deceleration rates in response to said autobrake turn-on signal.

A brake control system for applying and controlling a brake application means for a wheel of an aircraft independently of operator brake application comprising:

• signal generating means for producing a first signal that is related to the rotational speed of said wheel;
• reference generating means for generating a reference signal;
• rate selector means for manually selecting said reference signal indicative of a desired rate of aircraft deceleration;
• comparison means for comparing said first signal with said reference signal for generating an error signal indicative of the difference between said first signal and said reference signal;
• control means for providing a signal to said brake application means to apply brake pressure to said wheel independently of operator brake application in response to said error signal to provide a deceleration brake control signal for controlling said brake pressure in order to maintain said desired rate of deceleration;
• wheelspeed logic means connected to said signal generating means for providing a wheelspeed logic signal when said wheel has spun-up from substantially zero to a predetermined rotational speed;
• pilot-controlled logic means for providing an arming signal when automatic braking is to be initiated;
• and
• automatic brake logic means for enabling said control means upon the concurrence of said wheelspeed logic and said arming signals.

A deceleration control system for applying and controlling the brake application means associated with each wheel of a group of braked load-bearing wheels of an aircraft independently of operator brake application comprising:

• signal generating means for each of said wheels for producing a first signal that is related to the rotational speed of its associated wheel;
• reference generating means for generating a reference signal;
• rate selector means for manually selecting said reference signal indicative of a desired rate of aircraft deceleration;
• averaging means responsive to the first signal associated with each of said wheels to form an average signal therefrom;
• comparison means for comparing said average signal with said reference signal for generating an error signal indicative of the difference between said average signal and said reference signal;
• control means for providing a signal to said brake application means to apply brake pressure to said wheels of said group independently of operator brake application and responsive to said error signal to provide a deceleration brake control signal for controlling said brake pressure in order to maintain said desired rate of deceleration;
• wheelspeed logic means connected to at least one of said signal generating means for providing a wheelspeed logic signal when said associated wheel has spun-up from substantially zero to a predetermined rotational speed;
• pilot-controlled logic means for providing an arming signal when automatic braking is to be initiated;
• and
• automatic brake logic means for enabling said control means only upon the concurrence of said wheelspeed logic and said arming signals.

A deceleration control system for an aircraft having plural groups of braked load-bearing wheels for applying and controlling a brake application means for said wheels independently of operator brake applications, said system comprising:

• signal generating means associated with each of said wheels for producing a first signal that is related to the rotational speed of its associated wheels;
• reference generating means for generating a reference signal;
• rate selector means for manually selecting said reference signal indicative of a desired rate of aircraft deceleration;
• averaging means for each of said wheel groups responsive to the first signals associated with each of said wheels in said group to form an average signal therefrom;
• comparison means for each of said wheel groups for comparing said average signal for the associated wheel group of said reference signal for generating an error signal indicative of the difference between said average signal for the associated wheel group and said reference signal;
• control means associated with each group of wheels for providing a signal to said brake application means to apply brake pressure to said wheels independently of operator brake application and responsive to said error signal to provide a deceleration brake control signal for controlling said brake pressure in order to maintain said desired rate of deceleration;
• wheelspeed logic means connected to at least one of said signal generating means in each of said wheel groups for providing a wheelspeed logic signal when said associated wheels have spun-up from substantially zero to a predetermined rotational speed;
• pilot-controlled logic means for providing an arming signal when automatic braking is to be initiated;
• and
• automatic brake logic means for enabling each of said control means only upon the concurrence of said wheelspeed logic and said arming signals.