Description:Complete Specification:
The following specification describes and ascertains the nature of this
invention and the manner in which it is to be performed
2
Field of the invention
[0001] The present disclosure relates to a method and a system to assist in braking of
a vehicle and more particularly a method and a system to assist in braking of a
vehicle in an event of a 5 brake pedal slip.
Background of the invention
[0002] As per the 2019 data by the National Highway Traffic Safety Administration
(an agency of the U.S. federal government, the Department of Transportation),
10 24% of the total accidents occur due to pedal errors by the drivers. A brake pedal
slip is a pedal error where the foot of the driver slips the brake pedal while applying
the brake. Typically, three scenarios exist. In one scenario while applying the
brakes, the foot of the driver slips when the driver accidentally presses the edge of
the brake pedal. In another scenario, the foot of the driver slips gradually due to
15 less grip between foot and the brake pedal. In yet another scenario, the foot of the
driver slips away from the brake pedal and the accelerator pedal is pressed
accidentally.
[0003] The prior art JP2021183430 A2 proposes an emergency stop device at the time
of pedal error at which a vehicle suddenly stops because an engine is stopped and
20 moreover a brake is actuated when a driver strongly steps an accelerator pedal by
mistake. An emergency stop device comprises a limit switch which detects
overstepping of an accelerator pedal, a changeover part which turns on and off a
circuit of an engine start switch, equalizer compulsion slide means which makes it
possible to move an equalizer of a parking brake in a direction in which tensile
25 forces of a pair of right and left brake wires rises and actuates by a motor and a
control unit. The control unit receives an ON signal from the limit switch and stops
the engine by causing the changeover part to turn off the circuit of the engine start
switch and moreover generates braking force on rear wheels by rotating the motor
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in the direction rising the tensile force of the brake wire and causes it to stop
rotation of the motor at the ON signal of a detection sensor which detects
movement up to a position stopping the rear wheels. Consequently, the problem
can be solved by the emergency stop device at the time of error pedal.
5
[0004] In the prior art DE102009053824 A1 a hydraulic brake assistant controlling
method for vehicle, involves increasing brake pressure by low pressure supplied
to booster, and adapting gradient threshold value to low pressure supplied to brake
booster and/or to ambient air pressure. The method involves automatically
10 adjusting brake pressure acting on a brake of a vehicle by a brake assistant, and
deriving brake pressure gradient from characteristic of the brake pressure. The
brake assistant is activated when the brake pressure gradient lies above a brake
pressure gradient threshold value. The brake pressure is increased by low pressure
supplied to a brake booster. The brake pressure gradient threshold value is adapted
15 to the low pressure supplied to the brake booster and/or to ambient air pressure.
[0005] The available prior arts assist in braking when enough brake pressure is not
applied in times of panic braking, however, there are no solutions to detect a brake
pedal slip.
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[0006] Further, the available solution to assist in braking a vehicle further do not take
the scenarios into account where the driver’s foot accidentally slips from the brake
pedal to the accelerator. An efficient brake pedal slip assist is therefore needed that
can either be an independent system or can be embedded into the ESPs of a vehicle
25 as a value-added function.
Brief description of the accompanying drawings
4
An embodiment of the invention is described with reference to the following
accompanying drawings:
[0007] Figure 1 depicts a system to assist in braking of a vehicle in the event of a brake
pedal slip.
[0008] Figure 2 depicts a flowchart of a method to assist in braking of 5 a vehicle in the
event of a brake pedal slip.
Detailed description of the drawings
10 [0009] Figure 1 depicts a system to assist in braking of a vehicle in the event of a brake
pedal slip.
[0010] Referring to Figure 1 , a control module (1) is embedded in the Electronic
Stability program ESP (10) as the- brake pedal slip assist (BPSA) -to assist in braking
the vehicle in the event of brake pedal slip as a value added function. In an alternative
15 embodiment the said control module can be present independently with a computation
processor to execute the stored programs and with a storage unit. The ESP (10)
recognizes critical driving conditions and stabilizes the vehicle by wheel-individual
braking and engine control intervention with no need for actuating the brake. The ESP
system is developed to help the driver avoid the danger of losing the control of the
20 vehicle stability due to under-steering or over steering during cornering. The ESP has
two active safety system: the Antilock Braking System (ABS) (7) and the Traction
Control System (TCS) (8). ABS (7) prevents the wheels from locking during braking,
TCS (8) prevents the wheels from spinning when starting off and accelerating. The
ESP for has a communication network (17) to communicate with the engine control
25 unit (18). The ESP receives inputs (In the alternate embodiment, the control module
(1) receives the input) from wheel speed sensors (11), inertial sensor (12), accelerator
pedal position sensor (13), brake light switch (14), steering angle sensor (15) and the
input of measured engine torque (16).
5
[0011] The wheel speed sensors (11) measure the wheel speed in a contact-free way
via magnetic fields. The inertial sensors (12) are used to measure translational and
rotational accelerations. The accelerator pedal position sensor (13) sense the
accelerator position during the pressing of the accelerator pedal. The brake light switch
(14) controls the brake lights to indicate when brake is applied in the 5 vehicle. Steering
angle sensor (15) measures the steering wheel position angle and rate of turn and the
engine torque (16) is calculated by the engine control unit using torque sensors. The
ESP further has a human machine interface (5) to connect with the output devices in
the instrument cluster (6). Additionally, a diagnosis system (9) can be provided to
10 detect any errors and fix the entire brake pedal slip assist system.
[0012] Referring to Figure 1, disclosed is a control module (1) to assist in braking of
a vehicle in an event of a brake pedal slip, the said control module configured to:
-detect signals from a master cylinder pressure sensor (2);
-estimate a brake pressure;
15 -estimate a braking time;
-detect the event of brake pedal slip, wherein, the event of brake pedal slip is detected
based on a pressure gradient being greater than a threshold pressure gradient;
-communicate with a brake system (3) to apply the brake pressure in a dynamic manner
when the pressure gradient is greater than a threshold pressure gradient;
20 -communicate with the brake system (3) to provide deceleration of the vehicle at a
constant rate if the vehicle speed is greater than a threshold speed;
-deactivate the brake pedal slip assist when the driver resumes braking;
-detect signals from accelerator pedal position sensor (13); and
- send a torque reduction request to the engine control unit (18) in the event the driver
25 does not resume to braking and the accelerator pedal is pressed by the driver.
[0013] The pressure gradient is calculated by obtaining the difference between the
brake pressure obtained from a master cylinder pressure sensor (2) during application
6
of brake and the brake pressure obtained from the master cylinder pressure sensor
when the brake pedal is released; and the difference so obtained divided by the braking
time.
[0014] The threshold pressure gradient is obtained based on 5 comparing: the graphical
plot of pressure gradient values during an intentional pedal release versus the brake
pressure; and the graphical plot of pressure gradient values during a pedal slip event
versus the brake pressure. The control module (1) is in communication with a human
machine interface (5) to provide BPSA activation indication to output devices in an
10 instrument cluster (6).
[0015] The control module (1) is embedded into the ESP to provide assistance in
braking of the vehicle in the event of brake pedal slip as a value-added function. The
control module (1) is in communication with a master cylinder pressure sensor (2).
The master cylinder pressure sensor (2) detects the brake fluid pressure differentials
15 in the hydraulic system. The control module computes the pressure gradient based on
the difference in pressure between the event of applying the brake and releasing the
brake pedal in a unit braking time (time taken from pressing the pedal till the release
of the pedal). The control module then compares the said pressure gradient value so
computed, with a threshold pressure gradient value. The same threshold value is pre20
computed, vehicle specific and is fed into the system. The threshold pressure gradient
is obtained based on comparing the graphical plot of pressure gradient values during
an intentional pedal release versus the brake pressure, and the graphical plot of
pressure gradient values during a pedal slip event versus the brake pressure.
25 [0016] If the value of pressure gradient computed by the control module is greater
than the threshold pressure gradient value, the event of brake pedal slip is said to be
detected. Once the event of brake pedal slip is detected the control module interacts
with the brake system (3) to apply a brake pressure to the brake discs (4). The brake
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system (3) uses a hydraulic brake mechanism wherein brake fluid is used to transfer
pressure to brake discs (4).
[0017] According to an aspect of the invention, the ‘brake pressure’ 5 applied upon the
detection of brake pedal slip event can be dynamic in nature. For example, the brake
pressure for a vehicle when the brake pedal slip event is detected can be applied
dynamically to provide deceleration incrementally from 0.1g to 0.3g. The magnitude
of the dynamic brake pressure to be applied can be customized specific to the vehicle
10 and fed into the system.
[0018] According to another aspect of the invention, the ‘brake pressure’ applied upon
the detection of brake pedal slip event can be constant in nature depending upon the
vehicle speed. In the event the brake pedal slip is detected; and the vehicle speed is
greater than a threshold vehicle speed, a constant brake pressure can be applied. For
15 instance, for a vehicle in motion for which the event of brake pedal is detected and the
vehicle speed is greater than a threshold vehicle speed of 50Kmph, a constant brake
pressure can be applied to decelerate the vehicle by 0.3g. The magnitude of the
constant brake pressure to be applied and the threshold vehicle speed beyond which it
is to be applied can be customized specific to the vehicle and fed into the system.
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[0019] According to another aspect of the invention, the brake pedal slip assist
function of the control module (1) gets deactivated once the driver resumes to braking
the vehicle.
[0020] According to yet another aspect of the invention, a scenario where the driver’s
25 foot slips from the brake pedal to the accelerator is considered. In the event where
brake pedal slip is detected and the accelerator pedal is pressed (detected by the
accelerator pedal position sensor) a torque reduction request is sent by the ESP(10) to
the engine control unit (18). The control module (1) embedded in the ESP (10) is in
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communication with the communication network (17), through which the torque
reduction request is sent to the engine control unit.
[0021] It is to be noted that the control module (1) comprises of a computation
processor to execute the stored programs and a storage unit. The storage unit stores
the programs, reference values and inputs from the sensors to execute 5 the invention
[0022] Referring to figure 2, Figure 2 depicts a flowchart of a method to assist in
braking of a vehicle in the event of a brake pedal slip.
[0023] Disclosed is a method to assist in braking of a vehicle in an event of a brake
10 pedal slip, the method comprising the steps of:
-detecting the event of brake pedal slip (100), wherein, the event of brake pedal slip is
detected based on a pressure gradient being greater than a threshold pressure gradient;
-applying a brake pressure (200) to decelerate the vehicle in the event the brake pedal
slip is detected;
15 -deactivating the brake pedal slip assist (BPSA) (300) in the event the driver resumes
braking ; and sending a torque reduction request to the engine control unit (400) in the
event the driver does not resume to braking and the accelerator pedal is pressed by the
driver.
[0024] The pressure gradient is calculated by obtaining the difference between the
20 brake pressure obtained from a master cylinder pressure sensor (2) during application
of brake and the brake pressure obtained from the master cylinder pressure sensor
when the brake pedal is released; and the difference so obtained divided by the braking
time.
[0025] The threshold pressure gradient is obtained (100b) based on comparing: the
25 graphical plot of pressure gradient values during an intentional pedal release versus
brake pressure; and the graphical plot of pressure gradient values during a pedal slip
event versus brake pressure.
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[0026] The brake pressure is applied dynamically (200a) if the pressure gradient is
greater than the threshold pressure gradient; and the brake pressure is applied at a
constant rate (200b) if the vehicle speed is greater than a threshold speed.
[0027] Referring to figure 2, the first step is detecting the 5 event of brake pedal slip
(100). In order to detect the brake pedal slip event the pressure gradient is compared
to the threshold pressure gradient. The pressure gradient is calculated (100a) based on
the difference in pressure between the event of applying the brake and releasing the
brake pedal in a unit braking time (time taken from pressing the pedal till the release
10 of the pedal). The said calculated pressure gradient value is compared with a threshold
pressure gradient value. The same threshold value is pre-computed, vehicle specific
and is fed into the system. The threshold pressure gradient is obtained (100b) based
on comparing the graphical plot of pressure gradient values during an intentional pedal
release versus the brake pressure, and the graphical plot of pressure gradient values
15 during a pedal slip event versus the brake pressure. If the value of pressure gradient
computed by the control module is greater than the threshold pressure gradient value,
the event of brake pedal slip is said to be detected.
[0028] Once the event of brake pedal slip is detected the next step of applying a brake
20 pressure (200) to decelerate the vehicle follows. The brake pressure is applied
dynamically (200a) if the pressure gradient is greater than the threshold pressure
gradient; and the brake pressure is applied at a constant rate (200b) in the event if the
vehicle speed is greater than a threshold speed. The ‘brake pressure’ applied upon the
detection of brake pedal slip event can be dynamic. To cite an example, the brake
25 pressure for a vehicle when the brake pedal slip event is detected can be applied
dynamically to provide deceleration incrementally from 0.1g to 0.3g. The magnitude
of the dynamic brake pressure to be applied can be customized specific to the vehicle
and fed into the system.
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[0029] The ‘brake pressure’ applied upon the detection of brake pedal slip event can
be constant in nature depending upon the vehicle speed. In the event the brake pedal
slip is detected, and the vehicle speed is greater than a threshold vehicle speed, a
constant brake pressure can be applied. For instance, for a vehicle 5 in motion for which
the event of brake pedal is detected and the vehicle speed is greater than a threshold
vehicle speed of 50Kmph, a constant brake pressure can be applied to decelerate the
vehicle by 0.3g. The magnitude of the constant brake pressure to be applied and the
threshold vehicle speed beyond which it is to be applied can be customized specific to
10 the vehicle and fed into the system. The said brake pedal slip assist gets deactivated
(300) once the driver resumes to braking the vehicle.
[0030] In the event where brake pedal slip is detected and the accelerator pedal is
pressed (detected by the accelerator pedal position sensor) a torque reduction request
15 is sent by the ESP to the engine control unit (400).
[0031] The disclosure advantageously assists in braking the vehicle in the event of a
brake pedal slip. The system takes over the task of braking the vehicle till the time the
driver regains control over the brakes. The disclosure has wide implications when it
20 comes to preventing accidents and improving road safety. , Claims:We Claim
1. A method to assist in braking of a vehicle in an event of a brake pedal slip, the
25 method comprising the steps of:
- detecting the event of brake pedal slip (100), wherein, the event of brake
pedal slip is detected based on a pressure gradient being greater than a
threshold pressure gradient;
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- applying a brake pressure (200) to decelerate the vehicle in the event the
brake pedal slip is detected;
- deactivating the brake pedal slip assist (BPSA) (300) in the event the driver
resumes braking; and
- sending a torque reduction request to the 5 engine control unit (400) in the
event the driver does not resume to braking and the accelerator pedal is
pressed by the driver.
2. The method to assist in braking of a vehicle in an event of a brake pedal slip,
10 as claimed in Claim 1, wherein, the pressure gradient is calculated (100a) by
obtaining a difference between the brake pressure obtained from a master
cylinder pressure sensor during application of brake and the brake pressure
obtained from the master cylinder pressure sensor when the brake pedal is
released; and the difference so obtained divided by the braking time.
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3. The method to assist in braking of a vehicle in an event of a brake pedal slip,
as claimed in Claim 1, wherein, the threshold pressure gradient is obtained
(100b) based on comparing:
-the graphical plot of pressure gradient values during an intentional pedal
20 release versus brake pressure; and
-the graphical plot of pressure gradient values during a pedal slip event versus
brake pressure.
25 4. The method to assist in braking of a vehicle in an event of a brake pedal slip,
as claimed in Claim 1, wherein,
- the brake pressure is applied dynamically (200a) if the pressure gradient is
greater than the threshold pressure gradient; and
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- the brake pressure is applied at a constant rate (200b) if the vehicle speed is
greater than a threshold speed.
5. A control module (1) to assist in braking of a vehicle in an event of a brake
pedal slip, t 5 he said control module configured to:
- detect signals from a master cylinder pressure sensor (2);
- estimate the brake pressure
- estimate the braking time
- detect the event of brake pedal slip, wherein, the event of brake pedal slip is
10 detected based on a pressure gradient being greater than a threshold pressure
gradient;
- communicate with the brake system (3) to apply the brake pressure in a
dynamic manner when the pressure gradient is greater than a threshold pressure
gradient;
15 - communicate with the brake system (3) to provide deceleration of the vehicle
at a constant rate if the vehicle speed is greater than a threshold speed;
-deactivate the brake pedal slip assist when the driver resumes braking;
- detect signals from accelerator pedal position sensor (13); and
-send a torque reduction request to the engine control unit (18) in the event the
20 driver does not resume to braking and the accelerator pedal is pressed by the
driver.
6. The control module (1) to assist in braking of a vehicle in an event of a brake
pedal slip, as claimed in Claim 5, the pressure gradient is calculated by
25 obtaining the difference between the brake pressure obtained from a master
cylinder pressure sensor (2) during application of brake and the brake pressure
obtained from the master cylinder pressure sensor when the brake pedal is
released; and the difference so obtained divided by the braking time.
13
7. The control module (1) to assist in braking of a vehicle in an event of a brake
pedal slip, as claimed in Claim 5, wherein, the threshold pressure gradient is
obtained based on comparing:
-the graphical plot of pressure gradient values 5 during an intentional pedal
release versus the brake pressure; and
-the graphical plot of pressure gradient values during a pedal slip event versus
the brake pressure.
10
8. The control module (1) to assist in braking of a vehicle in an event of a brake
pedal slip, as claimed in Claim 5, wherein, the said control module is in
communication with a human machine interface (5) to provide Brake pedal slip
assist (BPSA) activation indication to output devices in an instrument cluster
15 (6).