An electro-mechanical braking-based by-wire mechanical braking auxiliary control strategy

Abstract

The present invention discloses a by-wire mechanical braking assistance control strategy based on electro-mechanical braking, belonging to the technical field of electric braking control. It includes the following steps: obstacle recognition; mode selection; whether to trigger the by-wire mechanical braking assistance EMBA. The present invention adopts the above-mentioned by-wire mechanical braking assistance control strategy based on electro-mechanical braking, changing the detection of the main cylinder pressure change gradient in the traditional EMBA to the detection of the brake pedal stroke change gradient and the change gradient of the pedal angle sensor. The transmission of the electric control signal is faster than that of the hydraulic change, shortening the arbitration time. Using the distance, vehicle speed, and acceleration information collected by the ADAS system, the danger level of the emergency is estimated, and the acceleration is converted into the clamping force at the wheel end in real time. The braking response speed becomes faster, and a larger braking deceleration can be provided instantaneously, shortening the braking distance.

Description

Technical Field

[0001] The present invention relates to the field of electric braking technology, and more particularly to a wire-controlled mechanical braking assist control strategy based on electro-mechanical braking. Background Art

[0002] Traditional Hydraulic Brake Assist detects the change gradient of the master cylinder pressure, wheel speed, and whether the driver steps on the brake pedal, and judges whether the change gradient of the master cylinder pressure exceeds the threshold value. This is to enable untrained drivers to supplement the braking pressure at the wheel end when stepping on the brake in an emergency, thereby reducing the braking distance and enhancing the braking safety. In the hydraulic braking method, the driver needs to adjust through the brake master cylinder to establish the braking pressure in the wheel cylinder of the brake caliper, generate the braking thrust, and act on the disc brake. However, due to the influence of the oil circuit transmission speed, the response is slow, and it will also increase the hysteresis time of the hydraulic brake assist function.

[0003] To solve the above problems, Electro-mechanical Brake Assist (EMBA) came into being. In an emergency, when the driver quickly steps on the brake pedal, by reading the change gradient of the pedal stroke of the pedal displacement sensor and the change gradient of the pedal angle of the pedal angle sensor, and judging the driver's braking intention through the magnitude of the change gradient, and sending the corresponding clamping force to the wheel-end motor through an electric control signal, the braking response time can be effectively shortened, and braking can be performed faster and more accurately. At the same time, Electro-mechanical Brake Assist (EMBA) can complement the Automatic Emergency Braking (AEB) function. According to the AEB emergency level calculated by the Advanced Driving Assistance System (ADAS), the threshold for triggering Electro-mechanical Brake Assist (EMBA) is reduced, and the triggering of Autonomous Emergency Braking (AEB) is avoided as much as possible, thus enhancing driving safety. Summary of the Invention

[0004] The object of the present invention is to provide a wire-controlled mechanical braking assist control strategy based on electro-mechanical braking, which solves the problems of judging the driver's braking intention by obtaining the change gradient of the pedal stroke and the change gradient of the pedal angle of the pedal through a pedal simulator; changing the traditional hydraulic brake assist to a wire-controlled mechanical brake assist at the wheel end; and adjusting the threshold for triggering EMBA by combining EMBA with AEB and combining the emergency level of AEB, making it easier to increase the clamping force at the EMB wheel end in an emergency.

[0005] To achieve the above object, the present invention provides a by-wire mechanical braking assist control strategy based on electro-mechanical braking, including the following steps:

[0006] S1. Obstacle recognition: Collect road condition information through the vehicle body millimeter wave radar and the vision camera, and determine whether there are obstacles that may cause collisions on the road where the vehicle is traveling;

[0007] S2. Mode selection: According to the obstacle recognition result in step S1, select the corresponding driving mode. If there are obstacles on the road where the vehicle is traveling, it is regarded as the obstacle mode. If there are no obstacles on the road where the vehicle is traveling, it is regarded as the normal driving mode;

[0008] S3. Whether to trigger the by-wire mechanical braking assist EMBA: Obtain the change gradient of the pedal travel and the change gradient of the pedal angle of the pedal through the pedal simulator to judge the driver's braking intention, and determine whether to activate the by-wire mechanical braking assist EMBA according to the braking conditions in the two modes in step S2.

[0009] Preferably, in step S3, if the vehicle is traveling in the obstacle mode, then:

[0010] The vehicle body millimeter wave radar and the vision camera calculate the safe collision distance within the controllable range in real time;

[0011] The ADAS system sends the AEB emergency danger level to the chassis domain controller;

[0012] According to the danger level, the chassis domain controller sends the pre-filled clamping force to the EMB wheel end controller to shorten the gap between the brake calipers.

[0013] Preferably, when the vehicle is traveling in the obstacle mode, judge the driver's intention through the change gradient of the pedal travel and the angle sensor, and adjust the trigger threshold of the by-wire mechanical braking assist EMBA in real time;

[0014] The higher the AEB emergency danger level, the smaller the change rate of the pedal travel and the angle sensor, and the by-wire mechanical braking assist EMBA can also be triggered.

[0015] Preferably, when the vehicle is traveling in the obstacle mode, if the driver has not stepped on the Epedal all the time, then trigger the AEB, and the chassis domain controller requests the maximum clamping force from the wheel end EMB controller to make the vehicle automatically brake emergently.

[0016] Preferably, in step S3, if the vehicle is traveling in the normal driving mode, then:

[0017] The chassis domain controller detects whether the driver steps on the brake pedal, whether the wheel speed reaches the minimum wheel speed to activate the electro-mechanical brake assist EMBA, and whether the wheel end clamping force exceeds the threshold to trigger the ABS;

[0018] When the driver steps on the brake, the wheel speed reaches the minimum wheel speed to activate the electro-mechanical brake assist EMBA and the wheel end clamping force does not exceed the threshold to trigger the ABS, the conditions for activating the electro-mechanical brake assist EMBA are met.

[0019] Preferably, when the vehicle is in the normal driving mode, when the gradient of the pedal stroke change or the gradient of the pedal angular displacement change exceeds the threshold, the electro-mechanical brake assist EMBA is activated.

[0020] Preferably, when the vehicle is in the normal driving mode and the electro-mechanical brake assist EMBA is triggered, the chassis domain controller requests the clamping force from the wheel end, and the EMB wheel end controller increases the clamping force to the threshold to trigger the ABS, not exceeding the critical value of the clamping force to trigger the ABS, so as to achieve braking.

[0021] Therefore, the present invention adopts a wire-controlled mechanical brake assist control strategy with the above structure, and has the following beneficial effects:

[0022] (1) In the present invention, the EMBA changes from the traditional detection of the master cylinder pressure change gradient to the detection of the brake pedal stroke change gradient and the change gradient of the pedal angle sensor. The transmission of the electric control signal is faster than the hydraulic change, shortening the arbitration time and making the braking response speed faster.

[0023] (2) The present invention uses the distance, vehicle speed, and acceleration information collected by the ADAS system to calculate the danger level of the emergency situation, and converts the acceleration into the clamping force of the wheel end in real time. For example, when it is recognized that there may be a dangerous situation, a relatively small clamping force is provided. When the driver discovers the danger and steps on the brake pedal, with the pre-filled clamping force, braking can be more effectively implemented. Moreover, compared with the traditional AEB function, the pre-filled clamping force can also be adjusted according to the danger level, and can instantaneously provide a greater braking deceleration, shortening the braking distance.

[0024] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flow schematic diagram of a wire-controlled mechanical brake assist control strategy based on electro-mechanical braking of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The technical solution of the present invention will be further described below with reference to the drawings and embodiments.

[0027] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention pertains. The terms "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Words such as "comprising" or "including" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. Words such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to indicate relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0028] Embodiment

[0029] As Figure 1 As shown, the present invention provides a by-wire mechanical braking assist control strategy based on electro-mechanical braking, wherein the device main body includes a wheel-end EMB, a chassis domain controller, an Epedal, a radar and a front camera. Its control strategy includes the following steps:

[0030] S1. Obstacle recognition: Collect road condition information through the vehicle body millimeter-wave radar and the vision camera, and determine whether there are obstacles that may cause collisions on the road where the vehicle is traveling.

[0031] S2. Mode selection: According to the obstacle recognition result in step S1, select the corresponding driving mode. If there are obstacles on the road where the vehicle is traveling, it is regarded as the obstacle mode; if there are no obstacles on the road where the vehicle is traveling, it is regarded as the normal driving mode.

[0032] S3. Whether to trigger the by-wire mechanical braking assist EMBA: Obtain the change gradient of the pedal travel and the change gradient of the pedal angle of the pedal through the pedal simulator to judge the driver's braking intention, and determine whether to activate the by-wire mechanical braking assist EMBA according to the braking conditions in the two modes in step S2.

[0033] If the vehicle is traveling in the obstacle mode, then:

[0034] The vehicle body millimeter-wave radar and the vision camera identify the target objects that may collide, and the sensor obtains information such as the speed, acceleration, and distance of the target objects. Calculate the time of possible collision in real time, and judge the danger level according to the length of the time. The shorter the time, the more dangerous.

[0035] The ADAS system then sends the AEB emergency danger level (increasing according to the danger situation) to the chassis domain controller, and then according to the danger level, the chassis domain controller sends the pre-filled clamping force to the EMB wheel-end controller to shorten the gap between the brake calipers. (When the danger level is Off, no pre-filled clamping force is provided.)

[0036] The formula is as follows:

[0037]

[0038] F clamp : Pre-filled clamping force

[0039] F Low : Clamping force for low danger level.

[0040] F Medium : Clamping force for medium danger level.

[0041] F High : Clamping force for high danger level.

[0042] L: Danger level, from low to high are Low, Medium, High.

[0043] In an emergency, adjust the trigger threshold of EMBA according to the danger level. The emergency level of AEB is divided into Off, Low, Medium, High from low to high. They respectively correspond to the trigger thresholds Gsth and Gθth of EMBA from high to low as normal, High, Medium, Low. After the trigger threshold of Electro-Mechanical Brake Assist (EMBA) is reduced, even if the driver gently presses the brake pedal and the change rates of the pedal stroke and angle sensors are relatively small, Electro-Mechanical Brake Assist (EMBA) can be triggered. At the same time, due to the pre-filled clamping force, the braking gap can be eliminated faster, the brake pads and brake discs can contact earlier, and the braking speed is faster.

[0044] If the driver has not stepped on the Epedal all the time, then trigger AEB, and the chassis domain controller requests the maximum clamping force from the wheel-end EMB controller to make the vehicle automatically brake emergently.

[0045] If the vehicle is in normal driving mode, then:

[0046] The chassis domain controller detects whether the driver steps on the brake pedal, detects whether the wheel speed reaches the minimum wheel speed to activate the Electro-Mechanical Brake Assist EMBA, and detects whether the wheel-end clamping force exceeds the threshold to trigger ABS;

[0047] When the driver steps on the brake, the wheel speed reaches the minimum wheel speed to activate the electro-mechanical brake assist (EMBA), and the wheel end clamping force does not exceed the threshold for triggering the anti-lock braking system (ABS), meeting the conditions for activating the electro-mechanical brake assist (EMBA).

[0048] Meanwhile, the values of the angle sensor and the pedal displacement sensor on the Epedal are read. When the gradient of the pedal travel change or the gradient of the pedal angular displacement change exceeds the threshold, the electro-mechanical brake assist (EMBA) is activated.

[0049] When the electro-mechanical brake assist (EMBA) is triggered, the chassis domain controller requests the clamping force from the wheel end. The EMB wheel end controller increases the clamping force to the threshold for triggering the ABS, but does not exceed the clamping force for triggering the ABS, so as to achieve braking.

[0050] Therefore, the present invention adopts the above-mentioned electro-mechanical brake assist control strategy based on electronic mechanical braking, changing the detection of the main cylinder pressure change gradient in the traditional EMBA to the detection of the pedal travel change gradient and the change gradient of the pedal angle sensor. The transmission of the electronic control signal is faster than the hydraulic change, shortening the arbitration time, making the braking response speed faster, being able to instantaneously provide a greater braking deceleration, and shortening the braking distance.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An electro-mechanical braking-based by-wire mechanical braking auxiliary control strategy, characterized in that, It includes the following steps: S1. Obstacle recognition: Collect road condition information through the vehicle body millimeter wave radar and vision camera, and judge whether there are obstacles that may cause collisions on the road where the vehicle is traveling; S2. Mode selection: Select the corresponding driving mode according to the obstacle recognition result in step S1. If there are obstacles on the road where the vehicle is traveling, it is regarded as the obstacle mode; if there are no obstacles on the road where the vehicle is traveling, it is regarded as the normal driving mode; S3. Whether to trigger the electronically controlled mechanical brake assist EMBA: Judge the driver's braking intention by obtaining the change gradient of the pedal stroke and the change gradient of the pedal angle of the pedal through the pedal simulator, and determine whether to activate the electronically controlled mechanical brake assist EMBA according to the braking conditions in the two modes in step S2; In step S3, if the vehicle is traveling in the obstacle mode, then: The vehicle body millimeter wave radar and vision camera calculate the safe collision distance within the controllable range in real time; The ADAS system sends the AEB emergency danger level to the chassis domain controller; According to the danger level, the chassis domain controller sends the pre-filled clamping force to the EMB wheel end controller to shorten the gap between the brake calipers; When the danger level is Off, no pre-filled clamping force is provided; The formula is as follows: F clamp : Pre-filled clamping force; F Low : Clamping force of low risk level; F Medium : Clamping force at medium risk level; F High : Clamping force of high danger level; L: Danger level, from low to high are Low, Medium, High; In an emergency, adjust the trigger threshold of EMBA according to the danger level. The emergency degree of AEB is divided into Off, Low, Medium, High from low to high; corresponding to the trigger thresholds Gsth and Gθth of EMBA from high to low are normal, High, Medium, Low; In step S3, if the vehicle is traveling in the normal driving mode, then: The chassis domain controller detects whether the driver steps on the brake pedal, whether the wheel speed reaches the minimum wheel speed to activate the electronically controlled mechanical brake assist EMBA, and whether the wheel end clamping force exceeds the threshold for triggering the ABS; When the driver steps on the brake, the wheel speed reaches the minimum wheel speed to activate the electronically controlled mechanical brake assist EMBA and the wheel end clamping force does not exceed the threshold for triggering the ABS, which meets the conditions for activating the electronically controlled mechanical brake assist EMBA; When the vehicle is traveling in the normal driving mode and the electronically controlled mechanical brake assist EMBA is triggered, the chassis domain controller requests the clamping force from the wheel end, and the EMB wheel end controller increases the clamping force to the threshold for triggering the ABS, not exceeding the critical value of the clamping force for triggering the ABS, so as to achieve braking.

2. The electronic-mechanical-brake-based by-wire mechanical brake assist control strategy according to claim 1, characterized in that: When the vehicle is traveling in the obstacle mode, judge the driver's intention through the change gradient of the pedal stroke and angle sensor, and adjust the trigger threshold of the electronically controlled mechanical brake assist EMBA in real time; According to the higher the AEB emergency danger level, the smaller the change rate of the pedal stroke and angle sensor, and the electronically controlled mechanical brake assist EMBA can also be triggered.

3. A wire-controlled mechanical braking assist control strategy based on electro-mechanical braking according to claim 1, characterized in that: When the vehicle is traveling in the obstacle mode, if the driver does not step on the Epedal all the time, then trigger the AEB, and the chassis domain controller requests the maximum clamping force from the wheel end EMB controller to make the vehicle automatically brake emergently.

4. A wire-controlled mechanical braking auxiliary control strategy based on electro-mechanical braking according to claim 1, characterized in that: When the vehicle is in the normal driving mode, if the gradient of the pedal travel change or the gradient of the pedal angular displacement change exceeds the threshold, the electromechanical brake assist (EMBA) is activated.

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