Method and system for assisting braking of a vehicle

Abstract

The present disclosure proposes a method and system for assisting in braking a vehicle when a brake pedal slips, in which a control module (1) is embedded in an electronic stability program (ESP) (10) as a brake pedal slip assist (BPSA) to assist in braking the vehicle when the brake pedal slips as a value-added function. A brake pedal slip event is detected based on the pressure gradient being greater than a threshold pressure gradient. If the brake pedal slip is detected, brake pressure is applied to decelerate the vehicle. If the driver resumes braking, the brake pedal slip assist (BPSA) function of the control module (1) will be deactivated. Further, if the driver does not resume braking and the driver depresses the accelerator pedal, a torque reduction request is issued to an engine control unit (18).

Description

[0001] The following specification describes and defines the nature of the invention and the manner in which it is to be performed. Technical Field

[0002] The present disclosure relates to a method and system for assisting vehicle braking, and more particularly to a method and system for assisting vehicle braking when the brake pedal slips. Background Art

[0003] According to data from the National Highway Traffic Safety Administration (an agency of the U.S. Department of Transportation, Federal Government) in 2019, 24% of total accidents were due to driver pedal errors. Brake pedal slip is a pedal error where the driver's foot slips off the brake pedal when braking is applied. There are generally three situations. In one situation, when braking is applied, the driver's foot slips when the driver accidentally presses the edge of the brake pedal. In another situation, the driver's foot gradually slips due to less grip between the foot and the brake pedal. In still another situation, the driver's foot slips off the brake pedal and accidentally presses the accelerator pedal.

[0004] The prior art JP2021183430 A2 proposes an emergency stop device for pedal errors in the case where a vehicle suddenly stops due to engine stop and, in addition, when the driver accidentally presses the accelerator pedal forcefully and the brake is actuated. The emergency stop device includes: a limit switch that detects overstepping of the accelerator pedal; a switching member that connects and disconnects the circuit of the engine start switch; an equalizer forced sliding device that allows the equalizer of the parking brake to move in the direction in which the pulling force of a pair of left and right brake cables increases, and is driven by a motor and a control unit. The control unit receives the ON signal from the limit switch and stops the engine by disconnecting the circuit of the engine start switch by the switching member; in addition, by rotating the motor in the direction in which the pulling force of the brake cable increases, a braking force is generated on the rear wheels, and when the detection sensor detects the ON signal of the position until the rear wheels stop, the motor is stopped from rotating. Therefore, the problem can be solved by the emergency stop device at the time of wrong pedal.

[0005] In the prior art DE102009053824 A1, a hydraulic brake assist control method for a vehicle includes increasing the brake pressure by providing low pressure to the booster, and adapting the gradient threshold to the low pressure provided to the brake booster and / or the ambient air pressure. The method includes automatically adjusting the brake pressure acting on the vehicle brakes by a brake assist system, and deriving a brake pressure gradient based on the characteristics of the brake pressure. When the brake pressure gradient is higher than the brake pressure gradient threshold, the brake assist system is activated. The brake pressure is increased by providing low pressure to the brake booster. The brake pressure gradient threshold is adapted to the low pressure provided to the brake booster and / or the ambient air pressure.

[0006] When insufficient braking pressure is applied during emergency braking, the available prior art auxiliary braking is obtained. However, there is no solution to detect brake pedal slip.

[0007] In addition, the available solutions for vehicle braking assistance do not consider the situation where the driver's foot accidentally slips from the brake pedal to the accelerator. Therefore, an efficient brake pedal slip assistance device is needed, which can be an independent system or can be embedded as a value-added function in the vehicle's ESP. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Embodiments of the present invention are described with reference to the following drawings:

[0009] Figure 1 A system for assisting vehicle braking in the case of brake pedal slip is depicted.

[0010] Figure 2 A flowchart of a method for assisting vehicle braking in the case of brake pedal slip is depicted. DETAILED DESCRIPTION

[0011] Figure 1 A system for assisting vehicle braking in the case of brake pedal slip is depicted.

[0012] See Figure 1 , a control module (1) is embedded in the electronic stability program ESP (10) as brake pedal slip assistance (BPSA) to assist in braking the vehicle in the case of brake pedal slip as a value-added function. In an alternative embodiment, the control module can exist independently, having a computing processor to execute a stored program, and having a storage unit. The ESP (10) identifies critical driving conditions and stabilizes the vehicle through independent wheel braking and engine control intervention without activating the brakes. The ESP system is developed to help the driver avoid the danger of losing control of the vehicle's stability due to understeering or oversteering during turning. The ESP has two active safety systems: an anti-lock braking system (ABS) (7) and a traction control system (TCS) (8). The ABS (7) prevents the wheels from locking during braking, and the TCS (8) prevents the wheels from spinning during starting and acceleration. The ESP has a communication network (17) for communicating with the engine control unit (18). The ESP receives inputs from a wheel speed sensor (11), an inertial sensor (12), an accelerator pedal position sensor (13), a brake light switch (14), a steering angle sensor (15) (in an alternative embodiment, the control module (1) receives the inputs) and an input of the measured engine torque (16).

[0013] The wheel speed sensor (11) measures the wheel speed in a non-contact manner through a magnetic field. The inertial sensor (12) is used to measure translational acceleration and rotational acceleration. The accelerator pedal position sensor (13) senses the accelerator position during depression of the accelerator pedal. The brake light switch (14) controls the brake lights to indicate when braking is applied in the vehicle. The steering angle sensor (15) measures the steering wheel position angle and the yaw rate, and the engine control unit calculates the engine torque using a torque sensor (16). The ESP also has a human-machine interface (5) for connecting to the output devices in the instrument panel (6). In addition, a diagnostic system (9) can be provided to detect any errors and repair the entire brake pedal slip assist system.

[0014] Reference Figure 1 , a control module (1) for assisting vehicle braking during brake pedal slip is disclosed, the control module being configured to:

[0015] - Detect a signal from the master cylinder pressure sensor (2);

[0016] - Estimate the braking pressure; - Estimate the braking time;

[0017] - Detect a brake pedal slip event, wherein the brake pedal slip event is detected based on a pressure gradient being greater than a threshold pressure gradient;

[0018] - When the pressure gradient is greater than the threshold pressure gradient, communicate with the brake system (3) to apply the braking pressure in a dynamic manner;

[0019] - If the vehicle speed is greater than a threshold speed, communicate with the brake system (3) to provide deceleration of the vehicle at a constant rate;

[0020] - When the driver resumes braking, deactivate the brake pedal slip assist;

[0021] - Detect a signal from the accelerator pedal position sensor (13); and

[0022] - If the driver does not resume braking and the driver depresses the accelerator pedal, send a torque reduction request to the engine control unit (18).

[0023] The pressure gradient is calculated by: obtaining the difference between the braking pressure obtained from the master cylinder pressure sensor (2) during application of braking and the braking pressure obtained from the master cylinder pressure sensor when the brake pedal is released; and dividing the obtained difference by the braking time.

[0024] The threshold pressure gradient is obtained by comparing: the graphical curve of the pressure gradient value versus the braking pressure during an intentional pedal release; and the graphical curve of the pressure gradient value versus the braking pressure during a pedal slip event. The control module (1) communicates with the human-machine interface (5) to provide a BPSA activation indication to the output device in the instrument panel (6).

[0025] The control module (1) is embedded in the ESP as a value-added function to provide braking assistance to the vehicle during a brake pedal slip. The control module (1) communicates with the master cylinder pressure sensor (2). The master cylinder pressure sensor (2) detects the pressure difference of the brake fluid in the hydraulic system. The control module calculates the pressure gradient based on the pressure difference between the events of applying the brake and releasing the brake pedal within the unit braking time (the time taken from pressing the pedal until releasing the pedal). Then, the control module compares the calculated pressure gradient value with the threshold pressure gradient value. This threshold is pre-calculated, vehicle-specific, and input into the system. The threshold pressure gradient is obtained by comparing the graphical curve of the pressure gradient value versus the braking pressure during an intentional pedal release and the graphical curve of the pressure gradient value versus the braking pressure during a pedal slip event.

[0026] If the pressure gradient value calculated by the control module is greater than the threshold pressure gradient value, a brake pedal slip event is said to be detected. Once a brake pedal slip event is detected, the control module will interact with the braking system (3) to apply a braking pressure to the brake disc (4). The braking system (3) employs a hydraulic braking mechanism, where the brake fluid is used to transfer the pressure to the brake disc (4).

[0027] According to one aspect of the present invention, the "braking pressure" applied when a brake pedal slip event is detected can be dynamic in nature. For example, when a brake pedal slip event is detected, the braking pressure for the vehicle can be dynamically applied to provide an increasing deceleration from 0.1g to 0.3g. The magnitude of the dynamic braking pressure to be applied can be customized for the vehicle and input into the system.

[0028] According to another aspect of the present invention, the "braking pressure" applied when a brake pedal slip event is detected can be constant according to the vehicle speed. If a brake pedal slip is detected and the vehicle speed is greater than the threshold vehicle speed, a constant braking pressure can be applied. For example, for a moving vehicle where a brake pedal event is detected and the vehicle speed is greater than the threshold vehicle speed of 50 km / h, a constant braking pressure can be applied to decelerate the vehicle at 0.3g. The magnitude of the constant braking pressure to be applied and the threshold vehicle speed (above which the said braking pressure will be applied) can be customized for the vehicle and input into the system.

[0029] According to another aspect of the present invention, once the driver resumes braking the vehicle, the brake pedal slip assist function of the control module (1) is deactivated.

[0030] According to yet another aspect of the present invention, the situation where the driver's foot slips from the brake pedal to the accelerator is considered. If brake pedal slip is detected and the accelerator pedal is depressed (detected by the accelerator pedal position sensor), then the ESP (10) sends a torque reduction request to the engine control unit (18). The control module (1) embedded in the ESP (10) communicates with the communication network (17), and the torque reduction request is sent to the engine control unit through the communication network (17).

[0031] It should be noted that the control module (1) includes a computing processor for executing stored programs and a storage unit. The storage unit stores programs, reference values, and inputs from sensors to implement the present invention.

[0032] Reference Figure 2 , Figure 2 depicts a flowchart of a method for assisting vehicle braking in the case of brake pedal slip.

[0033] Disclosed is a method for assisting vehicle braking when the brake pedal slips, the method comprising the following steps:

[0034] - Detecting a brake pedal slip event (100), wherein the brake pedal slip event is detected based on a pressure gradient being greater than a threshold pressure gradient;

[0035] - If a brake pedal slip is detected, applying a braking pressure (200) to decelerate the vehicle;

[0036] - If the driver resumes braking, deactivating the brake pedal slip assist (BPSA) (300); and if the driver does not resume braking and the driver depresses the accelerator pedal, sending a torque reduction request to the engine control unit (400).

[0037] The pressure gradient is calculated by obtaining the difference between the braking pressure obtained from the master cylinder pressure sensor (2) during braking application and the braking pressure obtained from the master cylinder pressure sensor when the brake pedal is released; and dividing the obtained difference by the braking time.

[0038] The threshold pressure gradient (100b) is obtained based on a comparison of: the pressure gradient value and the graphical curve of the braking pressure during intentional pedal release; and the pressure gradient value and the graphical curve of the braking pressure during a pedal slip event.

[0039] If the pressure gradient is greater than the threshold pressure gradient, dynamically applying a braking pressure (200a); and if the vehicle speed is greater than the threshold speed, applying a braking pressure at a constant rate (200b).

[0040] Reference Figure 2 , the first step is to detect a brake pedal slip event (100). To detect a brake pedal slip event, the pressure gradient is compared with a threshold pressure gradient. The pressure gradient is calculated based on the pressure difference between the events of applying and releasing the brake pedal within a unit braking time (the time taken from pressing the pedal until releasing the pedal) (100a). The calculated pressure gradient value is compared with the threshold pressure gradient value. This threshold is pre-calculated, vehicle-specific, and input into the system. The threshold pressure gradient is obtained by comparing the pressure gradient value during an intentional pedal release with the graph of the brake pressure and the pressure gradient value during a pedal slip event with the graph of the brake pressure (100b). If the pressure gradient value calculated by the control module is greater than the threshold pressure gradient value, a brake pedal slip event is said to be detected.

[0041] Once a brake pedal slip event is detected, the next step is to apply a braking pressure (200) to decelerate the vehicle. If the pressure gradient is greater than the threshold pressure gradient, the braking pressure is applied dynamically (200a); if the vehicle speed is greater than the threshold speed, the braking pressure is applied at a constant rate (200b). The "braking pressure" applied when a brake pedal slip event is detected can be dynamic. For example, when a brake pedal slip event is detected, the braking pressure for the vehicle can be applied dynamically to provide an increasing deceleration from 0.1g to 0.3g. The magnitude of the dynamic braking pressure to be applied can be customized for the vehicle and input into the system.

[0042] The "braking pressure" applied when a brake pedal slip event is detected can be essentially constant depending on the vehicle speed. If a brake pedal slip is detected and the vehicle speed is greater than the threshold vehicle speed, a constant braking pressure can be applied. For example, for a moving vehicle where a brake pedal event is detected and the vehicle speed is greater than the threshold vehicle speed of 50 km / h, a constant braking pressure can be applied to decelerate the vehicle at 0.3g. The magnitude of the constant braking pressure to be applied and the threshold vehicle speed (above which the braking pressure will be applied) can be customized for the vehicle and input into the system. Once the driver resumes braking the vehicle, the brake pedal slip assist is deactivated (300).

[0043] If a brake pedal slip is detected and the accelerator pedal is depressed (detected by the accelerator pedal position sensor), the ESP sends a torque reduction request to the engine control unit (400).

[0044] The present disclosure advantageously assists vehicle braking in the case of a brake pedal slip. The system takes over the vehicle braking task until the driver regains control of the brakes. The present disclosure has a wide impact on accident prevention and road safety.

Claims

1. A method for assisting vehicle braking when the brake pedal slips, the method comprising the following steps: - Detect a brake pedal slip event (100), wherein the brake pedal slip event is detected based on a pressure gradient being greater than a threshold pressure gradient; - If a brake pedal slip is detected, apply a braking pressure (200) to decelerate the vehicle; - If the driver resumes braking, deactivate the brake pedal slip assist (BPSA) (300); - If the driver does not resume braking and the driver depresses the accelerator pedal, send a torque reduction request to the engine control unit (400).

2. The method for assisting vehicle braking during brake pedal slippage according to claim 1, wherein, By obtaining the difference between the braking pressure obtained from the master cylinder pressure sensor during braking application and the braking pressure obtained from the master cylinder pressure sensor when the brake pedal is released; And calculating the pressure gradient (100a) by dividing the obtained difference by the braking time.

3. The method for assisting vehicle braking during brake pedal slip according to claim 1, wherein, Obtaining a threshold pressure gradient (100b) based on a comparison of the following two items: - The graphical curve of the pressure gradient value and the braking pressure during intentional pedal release; - The graphical curve of the pressure gradient value and the braking pressure during a pedal slip event.

4. The method for assisting vehicle braking when the brake pedal slips according to claim 1, wherein If the pressure gradient is greater than the threshold pressure gradient, apply the braking pressure dynamically (200a); If the vehicle speed is greater than the threshold speed, apply the braking pressure at a constant rate (200b).

5. A control module (1) for assisting vehicle braking when the brake pedal slips, the control module configured to: - Detect a signal from the master cylinder pressure sensor (2); - Estimate the braking pressure; - Estimate the braking time; - Detect a brake pedal slip event, wherein the brake pedal slip event is detected based on a pressure gradient being greater than a threshold pressure gradient; - When the pressure gradient is greater than the threshold pressure gradient, communicate with the braking system (3) to apply the braking pressure in a dynamic manner; - If the vehicle speed is greater than the threshold speed, communicate with the braking system (3) to provide deceleration of the vehicle at a constant rate; - When the driver resumes braking, deactivate the brake pedal slip assist; - Detect a signal from the accelerator pedal position sensor (13); and - If the driver does not resume braking and the driver depresses the accelerator pedal, send a torque reduction request to the engine control unit (18).

6. The control module (1) for assisting vehicle braking during brake pedal slip according to claim 5, wherein, By obtaining the difference between the braking pressure obtained from the master cylinder pressure sensor (2) during braking application and the braking pressure obtained from the master cylinder pressure sensor when the brake pedal is released; And calculating the pressure gradient by dividing the obtained difference by the braking time.

7. The control module (1) for assisting vehicle braking during brake pedal slip according to claim 5, wherein, The threshold pressure gradient is obtained based on a comparison of the following two items: - The graphical curve of the pressure gradient value and the braking pressure during intentional pedal release; And - The graphical curve of the pressure gradient value and the braking pressure during a pedal slip event.

8. The control module (1) for assisting vehicle braking during brake pedal slip according to claim 5, wherein, The control module communicates with the human-machine interface (5) to provide a brake pedal slip assist (BPSA) activation indication to the output device in the instrument panel (6).

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