CN115158304B - Automatic emergency braking control system and method - Google Patents

Automatic emergency braking control system and method Download PDF

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Publication number
CN115158304B
CN115158304B CN202210842646.9A CN202210842646A CN115158304B CN 115158304 B CN115158304 B CN 115158304B CN 202210842646 A CN202210842646 A CN 202210842646A CN 115158304 B CN115158304 B CN 115158304B
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vehicle
automatic emergency
collision time
preset
emergency brake
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CN115158304A (en
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囤金军
陈振国
赵红光
侯进森
朱岩朋
李振洋
杨政栋
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Zhongtong Bus Holding Co Ltd
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Zhongtong Bus Holding Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
    • B60W30/08—Active safety systems predicting or avoiding probable or impending collision or attempting to minimise its consequences
    • B60W30/09—Taking automatic action to avoid collision, e.g. braking and steering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units, or advanced driver assistance systems for ensuring comfort, stability and safety or drive control systems for propelling or retarding the vehicle
    • B60W30/08—Active safety systems predicting or avoiding probable or impending collision or attempting to minimise its consequences
    • B60W30/095—Predicting travel path or likelihood of collision
    • B60W30/0956—Predicting travel path or likelihood of collision the prediction being responsive to traffic or environmental parameters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2552/00—Input parameters relating to infrastructure
    • B60W2552/50—Barriers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2554/00—Input parameters relating to objects
    • B60W2554/80—Spatial relation or speed relative to objects
    • B60W2554/802—Longitudinal distance
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2554/00—Input parameters relating to objects
    • B60W2554/80—Spatial relation or speed relative to objects
    • B60W2554/804—Relative longitudinal speed

Abstract

The invention discloses an automatic emergency braking control system, which comprises: the system comprises a front road information sensing module, a vehicle information sensing module, an automatic emergency brake controller, an alarm module and a brake actuating mechanism module; the automatic emergency braking controller receives the road information and the vehicle information in front of the vehicle, which are sent by the sensing module, calculates the collision time, determines a preset collision time threshold according to the vehicle speed, compares the collision time with the preset collision time threshold, sends out an emergency braking execution instruction according to the comparison result, and the braking execution mechanism module receives the instruction and executes corresponding automatic emergency braking operation. The invention realizes the graded braking control of different vehicle speeds by comparing the collision time with the preset collision time threshold value, thereby greatly improving the riding comfort of passengers while ensuring the driving safety.

Description

Automatic emergency braking control system and method
Technical Field
The invention relates to the technical field of traffic safety, in particular to an automatic emergency braking control system and method.
Background
With the gradual increase of the holding capacity of vehicles in China, the automobile auxiliary driving technology, in particular to the automatic emergency braking (AEB, autonomous Emergency Braking) technology of active safety, is rapidly developed. The automatic emergency braking AEB is an active safety technology for avoiding or relieving collision through automatic emergency braking, the AEB acquires operation signals of targets in front of a vehicle, such as relative speed, relative distance and the like of the vehicle and an obstacle through an environment sensor such as a radar, a camera and the like, and meanwhile, by combining the motion state of the vehicle, the risk of the front collision is judged, and early warning is sent out or emergency braking is executed, so that the accident caused by unconscious and non-operation of a driver is reduced.
In the existing AEB technology, the control strategy is to collect road condition information through external sensing devices such as millimeter wave radar, laser radar, front-view cameras and other environmental sensors, screen out a main target object, calculate the collision time (TTC, time to collision) between the vehicle and the target object, compare with a preset collision time threshold in advance, and start AEB early warning and emergency braking functions when the calculated collision time is smaller than the preset collision time threshold, so as to achieve the purpose of active safety.
However, in the automatic emergency braking control technology, the preset collision time threshold is generally set to a minimum value capable of ensuring no collision, and when the vehicle is in emergency braking, the brake-by-wire actuating mechanism of the automatic emergency braking control technology often outputs the maximum braking deceleration to brake, so that the maximum deceleration is realized in a short time, and passengers in the vehicle have poor experience and poor comfort.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides an automatic emergency braking control system and an automatic emergency braking control method, which are used for calculating the collision time of a vehicle and a road obstacle according to vehicle information and road information, determining a preset collision time threshold according to the vehicle speed, outputting a braking deceleration value for braking, realizing graded braking control of different vehicle speeds, ensuring the driving safety and greatly improving the riding comfort of passengers.
In a first aspect, the present disclosure provides an automatic emergency brake control system:
an automatic emergency brake control system comprising: the system comprises a front road information sensing module, a vehicle information sensing module, an automatic emergency brake controller, an alarm module and a brake actuating mechanism module;
the front road information sensing module is used for acquiring front road information of a vehicle and sending the front road information to the automatic emergency brake controller in the running process of the vehicle; the forward road information includes a relative distance of a forward obstacle from the vehicle, a relative speed of the forward obstacle and the vehicle;
the vehicle information sensing module is used for acquiring vehicle information and sending the vehicle information to the automatic emergency brake controller in the running process of the vehicle; the vehicle information comprises a vehicle gear, a vehicle speed and an actual steering angle of the steering wheel;
the automatic emergency brake controller is used for receiving front road information and vehicle information of a vehicle in the running process of the vehicle, carrying out logic judgment according to the front road information and the vehicle information, outputting braking deceleration corresponding to the vehicle, sending an emergency brake executing instruction containing the braking deceleration to the brake executing mechanism module and sending an alarm signal to the alarm module;
the alarm module is used for sending out an alarm according to the alarm signal;
the brake actuating mechanism module is used for receiving the emergency brake actuating instruction and executing braking deceleration of corresponding deceleration according to the braking deceleration in the emergency brake actuating instruction.
According to a further technical scheme, the front road information sensing module comprises a front-view camera and a millimeter wave radar, the front-view camera takes the position of a lens as a coordinate origin, the running direction of a vehicle is taken as the positive direction of an X axis, the anticlockwise direction perpendicular to the X axis is taken as the positive direction of a Y axis, and a rectangular coordinate system is established;
based on the rectangular coordinate system, according to the road image in front of the vehicle acquired in real time by the forward-looking camera, the relative distance between the front obstacle and the vehicle and the relative speed between the front obstacle and the vehicle are calculated respectively by combining the ranging information output by the millimeter wave radar.
According to a further technical scheme, the relative distance between the front obstacle and the vehicle is the distance between the front obstacle and the X direction taking the front camera as an origin;
the relative speed of the front obstacle and the vehicle is a speed in the X direction of the front obstacle with respect to the front view camera as an origin.
According to a further technical scheme, the automatic emergency braking controller carries out logic judgment, specifically:
judging whether to start automatic emergency braking control according to vehicle information: when the gear of the vehicle is the D gear, the speed is more than 0, and the actual turning angle of the steering wheel is less than 30 degrees, starting automatic emergency braking control, otherwise, not starting the automatic emergency braking control;
if the automatic emergency braking control is started, calculating the time required by collision between the vehicle and the front obstacle according to the relative distance between the front obstacle and the vehicle and the relative speed between the front obstacle and the vehicle;
determining a preset collision time threshold according to the current speed of the vehicle; the preset collision time threshold value is in direct proportion to the vehicle speed;
comparing the collision time with a preset collision time threshold, and when the collision time is more than the preset collision time threshold, not performing braking operation; and when the collision time is less than or equal to a preset collision time threshold value, performing braking operation.
According to the further technical scheme, when the collision time is detected to be less than or equal to the preset collision time threshold value, alarm information is sent out, timing is started at the same time, and if the collision time is detected to be less than or equal to the preset collision time threshold value within a set time period, an emergency braking execution instruction is sent out; the emergency brake execution instruction includes executing a preset brake deceleration of the emergency brake.
According to a further technical scheme, in the process of executing emergency braking by the brake executing mechanism module, when the automatic emergency braking controller detects that the vehicle continuously meets the condition of stopping the emergency braking in a set time period, an emergency braking executing instruction is sent out;
the brake actuating mechanism module receives an emergency brake actuating stopping instruction, releases braking force and stops automatic braking.
According to the further technical scheme, the meeting condition of stopping emergency braking is that the speed of the vehicle is less than 1km/h, or the preset time is greater than the preset collision time threshold value or the preset collision time threshold value is greater than 4s.
According to a further technical scheme, the automatic emergency braking control system further comprises a self-checking module, wherein the self-checking module is used for detecting whether each module of the automatic emergency braking control system operates normally or not and sending self-checking information to the automatic emergency braking controller.
In a second aspect, the present disclosure provides an automatic emergency brake control method, including:
after the vehicle is started, the automatic emergency braking control system is powered on for self-checking, and if no fault is detected, the automatic emergency braking control system enters a standby state;
opening an automatic emergency brake control system switch to enable the automatic emergency brake control system to enter an enabling state;
acquiring front road information and vehicle information of a vehicle; the front road information includes: a relative distance of a forward obstacle from the vehicle, a relative speed of the forward obstacle from the vehicle, the vehicle information including: vehicle gear, vehicle speed and steering wheel actual rotation angle;
and carrying out logic judgment according to the front road information and the vehicle information, and carrying out corresponding automatic emergency braking operation according to a logic judgment result.
According to a further technical scheme, logic judgment is carried out according to the front road information and the vehicle information, and corresponding automatic emergency braking operation is carried out according to a logic judgment result, specifically:
judging whether to start automatic emergency braking control according to vehicle information: when the gear of the vehicle is the D gear, the speed is more than 0, and the actual turning angle of the steering wheel is less than 30 degrees, starting automatic emergency braking control, otherwise, not starting the automatic emergency braking control;
if the automatic emergency braking control is started, calculating the time required by collision between the vehicle and the front obstacle according to the relative distance between the front obstacle and the vehicle and the relative speed between the front obstacle and the vehicle;
determining a preset collision time threshold according to the current speed of the vehicle; the preset collision time threshold value is in direct proportion to the vehicle speed;
comparing the collision time with a preset collision time threshold, and when the collision time is more than the preset collision time threshold, not performing braking operation; when the collision time is less than or equal to the preset collision time threshold value, alarm information is sent out, timing is started at the same time, and if the collision time is detected to be less than or equal to the preset collision time threshold value within the set time period, emergency braking is automatically executed according to preset braking deceleration.
The one or more of the above technical solutions have the following beneficial effects:
according to the automatic emergency braking control system and method, according to information of obstacles existing on a road in front of a vehicle and information of the vehicle, collision time between the vehicle and the obstacles is calculated, different preset collision time thresholds are determined according to different vehicle speeds, logic judgment is carried out by comparing the collision time with the preset collision time thresholds, grading braking control of different vehicle speeds is achieved, driving safety is guaranteed, and meanwhile riding comfort of passengers is greatly improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
FIG. 1 is a schematic diagram of an automatic emergency brake control system according to an embodiment of the present invention;
fig. 2 is a flowchart of an automatic emergency brake control method according to a second embodiment of the invention.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
Example 1
As shown in fig. 1, the present embodiment provides an automatic emergency brake control system including: the structure and function of the front road information sensing module, the vehicle information sensing module, the automatic emergency brake controller, the alarm module and the brake actuator module are described below.
The front road information sensing module is used for acquiring front road information of a vehicle and sending the front road information to the automatic emergency braking controller in the running process of the vehicle, and the front road information comprises: the relative distance of the forward obstacle from the vehicle, the relative speed of the forward obstacle from the vehicle.
Optionally, the front road information sensing module is configured to sense external environment information in front of the vehicle and identify a situation of an obstacle in front of the vehicle during running of the vehicle, so as to obtain front road information of the vehicle. The front road information sensing module can be realized through software and/or hardware, the front obstacle of the vehicle can be a vehicle and a pedestrian positioned in front of the vehicle, and the front road information sensing module can identify the condition of the vehicle and the pedestrian positioned in front of the vehicle.
In this embodiment, the front road information perception module includes forward looking camera and millimeter wave radar, millimeter wave radar installs in front bumper central authorities, forward looking camera installs in front windshield positive centre, gathers the front road image of vehicle travel process in real time, combines millimeter wave radar, screens out the barrier in the vehicle travel process in the front road image of acquisition: when there is a lane, the most dangerous object on the current lane (i.e., the object closest to the vehicle) is taken as an obstacle, and when there is no lane line, objects within a range of 1.5m from the left to the right of the vehicle are taken as obstacles.
The front-view camera takes the position of the lens as the origin of coordinates, takes the running direction of the vehicle as the positive direction of the X axis, and takes the anticlockwise direction perpendicular to the X axis as the positive direction of the Y axis, so as to establish a rectangular coordinate system. Based on the rectangular coordinate system, according to the road image in front of the vehicle acquired in real time by the forward-looking camera, the relative distance between the front obstacle and the vehicle and the relative speed between the front obstacle and the vehicle are calculated respectively by combining the ranging information output by the millimeter wave radar.
The relative distance between the front obstacle and the vehicle is the distance between the front obstacle and the X direction of the original point of the front camera, and is calculated according to the front road image of the vehicle at the current moment, the millimeter wave radar and the position of the obstacle and the width of the obstacle detected from the image. And in the calculation process, a plurality of frames are used for smooth filtering, so that measurement errors are avoided.
The relative speed between the front obstacle and the vehicle is the speed in the X direction of the front obstacle with respect to the origin of the front camera, and is calculated from the image of the road ahead of the vehicle at the current time, the position of the obstacle and the width of the obstacle detected from the image by combining with the millimeter wave radar. Wherein the calculation process uses the size transformation output of the obstacle in the image, and the value is transformed with each frame.
In this embodiment, the front road information sensing module adopts an ARS408 millimeter wave radar and a Motovis forward looking camera, and the Motovis camera fuses millimeter wave radar information, so that the front target can be accurately identified through an internal algorithm, and information such as the relative position, the relative speed, the relative acceleration, the target type and the like of the front target is obtained and output to the automatic emergency brake controller.
The vehicle information sensing module is used for acquiring vehicle information in the running process of the vehicle and sending the vehicle information to the automatic emergency braking controller, wherein the vehicle information comprises a vehicle gear, a vehicle speed and an actual steering angle of a steering wheel.
The automatic emergency brake controller is used for receiving front road information and vehicle information of a vehicle in the running process of the vehicle, carrying out logic judgment according to the front road information and the vehicle information, outputting braking deceleration corresponding to the vehicle, sending an emergency brake executing instruction containing the braking deceleration to the brake executing mechanism module, and sending an alarm signal to the alarm module.
In this embodiment, the automatic emergency brake controller adopts a main control chip with 32-bit TC275T in inflight ice, has 1-way key signal, 2-way hard wire wake-up signal, 6-way power supply voltage, 8-way 5V voltage output, 2-way CAN communication interface, and supports CAN specific frame wake-up. The automatic emergency braking controller is arranged in the control box in the vehicle and is respectively connected with the front road information sensing module, the vehicle information sensing module, the alarm module and the braking executing mechanism module through the CAN bus.
And the alarm module is used for sending out an alarm according to the alarm signal.
The brake actuating mechanism module is used for receiving the emergency brake actuating instruction and carrying out braking deceleration of corresponding deceleration according to the braking deceleration in the emergency brake actuating instruction.
The automatic emergency braking controller carries out logic judgment, and specifically comprises the following steps:
judging whether to start automatic emergency braking control according to vehicle information: when the gear of the vehicle is D gear and the speed is more than 0 and the actual turning angle of the steering wheel is less than 30 degrees, the automatic emergency braking control is started, otherwise, the automatic emergency braking control is not started.
If the automatic emergency braking control is started, according to the relative distance between the front obstacle and the vehicle and the relative speed between the front obstacle and the vehicle, the time required by the collision between the vehicle and the front obstacle, namely the collision time, is calculated, and the formula is as follows:
Figure BDA0003751721020000081
in the above, TTC cr The collision time is expressed in seconds(s), x c (t) represents the relative distance of the obstacle in front of the moment t from the vehicle, and the measurement unit is meter (m), v r (t) represents the relative speed of the obstacle and the vehicle in front of the time t, and the unit of measurement is meter/second (m/s).
Determining collision grades based on the current speed of the vehicle, wherein different collision grades correspond to different preset collision time thresholds TTC th The greater the vehicle speed, the higher the corresponding collision level, and the corresponding preset collisionThe greater the strike time threshold. That is, a preset time to collision threshold TTC is determined based on the current speed of the vehicle th 。
Preset time to collision threshold TTC th The method is characterized in that the method is used for calibrating the quantity and is obtained by a real vehicle calibration test, and the specific calibration scheme is as follows: presetting a preliminary preset collision time threshold TTC according to test experience th The same vehicle is used as a sample vehicle, and the vehicle speeds of 10km/h, 20km/h, 30km/h, 40km/h, 50km/h and 60km/h are respectively used for driving the sample vehicle to a front static obstacle, so that emergency braking is realized, and after the sample vehicle is static, the distance L between the sample vehicle and the front obstacle is tested, and the distance L between the sample vehicle and the front obstacle is 1.5m<L<2m, if this range is not satisfied, then the given TTC is changed th Repeating the test until 1.5m<L<2m. Thereby obtaining a preset time to collision threshold TTC th -a vehicle speed curve based on which a corresponding preset time to collision threshold TTC is determined based on the current speed of the vehicle th 。
Comparing time to collision TTC cr And a preset time to collision threshold TTC th TTC when collision time cr TTC > preset time to collision threshold th When the brake is not operated; TTC at time of collision cr TTC (time to collision) threshold value less than or equal to preset th In the event of a braking operation, in particular, in the event of detection of a time to collision TTC cr TTC (time to collision) threshold value less than or equal to preset th When the time is counted while sending out alarm information, if collision time TTC is always detected in a set time period cr TTC (time to collision) threshold value less than or equal to preset th An emergency brake execution instruction is issued, the emergency brake execution instruction including brake deceleration information for executing the emergency brake.
The braking deceleration is based on the current speed of the vehicle and/or the current time to collision TTC cr Different from the above, the braking deceleration is set similar to the preset time to collision threshold TTC th The setting of the system takes the relative speed and/or the collision time of the sample car as independent variables, and the relative speed and/or the collision time TTC of the brake deceleration is finally obtained through the sample car calibration test cr Based on which the current speed and/or the collision time of the vehicle can be determinedA corresponding braking deceleration is determined. Further, the braking deceleration may be a deceleration that decelerates at the relative vehicle speed to ensure occupant compliance.
In the present embodiment, the set period of time is set to 0.2s, when the collision time TTC is detected for 0.2s cr TTC (time to collision) threshold value less than or equal to preset th And when the emergency braking is performed, an emergency braking execution instruction is sent to the braking execution mechanism module.
In the process of executing the emergency braking, when the condition that the vehicle continuously meets the emergency braking stopping condition in the set time period is detected, an emergency braking stopping executing instruction is sent out. The brake actuating mechanism module receives an emergency brake actuating stopping instruction, releases braking force and stops automatic braking. Wherein the meeting condition of stopping the emergency braking is that the speed of the vehicle is less than 1km/h or TTC cr TTC > preset time to collision threshold th Or a preset time to collision threshold TTC th > 4s (seconds).
As one or more embodiments, the automatic emergency brake control system further includes a self-checking module for detecting whether each module of the automatic emergency brake control system operates normally, and transmitting self-checking information to the automatic emergency brake controller. And the automatic emergency braking controller judges whether the system is faulty or not according to the received self-checking information, if no fault exists, the automatic emergency braking control system is started to perform braking control, and if the fault exists, an alarm signal is sent to the alarm module to perform alarm.
According to the automatic emergency braking control system, the information of the obstacle existing on the road in front of the vehicle and the information of the vehicle are acquired in real time through the road information sensing module in front of the vehicle and the vehicle information sensing module, the collision time between the vehicle and the obstacle is calculated by the automatic emergency automatic controller, different preset collision time thresholds are determined according to different vehicle speeds, logic judgment is carried out by comparing the collision time with the preset collision time thresholds, grading braking control of different vehicle speeds is achieved, and riding comfort of passengers is greatly improved while driving safety is guaranteed.
Example two
The embodiment provides an automatic emergency braking control method, as shown in fig. 2, comprising the following steps:
after the vehicle is started, the automatic emergency braking control system is powered on for self-checking, and if no fault is detected, the automatic emergency braking control system enters a standby state;
opening an automatic emergency brake control system switch to enable the automatic emergency brake control system to enter an enabling state;
acquiring front road information and vehicle information of a vehicle; the front road information includes: a relative distance of a forward obstacle from the vehicle, a relative speed of the forward obstacle from the vehicle, the vehicle information including: vehicle gear, vehicle speed and steering wheel actual rotation angle;
and carrying out logic judgment according to the front road information and the vehicle information, and carrying out automatic emergency braking according to a logic judgment result.
The logic judgment is carried out according to the front road information and the vehicle information, specifically:
judging whether to start automatic emergency braking control according to vehicle information; when the gear of the vehicle is D gear and the speed is more than 0 and the actual turning angle of the steering wheel is less than 30 degrees, the automatic emergency braking control is started, otherwise, the automatic emergency braking control is not started.
If the automatic emergency braking control is started, according to the relative distance between the front obstacle and the vehicle and the relative speed between the front obstacle and the vehicle, the time required by the collision between the vehicle and the front obstacle, namely the collision time, is calculated, and the formula is as follows:
Figure BDA0003751721020000101
in the above, TTC cr The collision time is expressed in seconds(s), x c (t) represents the relative distance of the obstacle in front of the moment t from the vehicle, and the measurement unit is meter (m), v r (t) represents the relative speed of the obstacle and the vehicle in front of the time t, and the measurement unit is meter/second(m/s)。
Determining collision grades based on the current speed of the vehicle, wherein different collision grades correspond to different preset collision time thresholds TTC th The greater the vehicle speed, the higher the corresponding collision level and the greater the corresponding preset collision time threshold. That is, a preset time to collision threshold TTC is determined based on the current speed of the vehicle th 。
Comparing time to collision TTC cr And a preset time to collision threshold TTC th And executing corresponding operations according to the comparison result:
TTC at time of collision cr TTC > preset time to collision threshold th When the brake is not operated;
TTC at time of collision cr TTC (time to collision) threshold value less than or equal to preset th In the event of a braking operation, in particular, in the event of detection of a time to collision TTC cr TTC (time to collision) threshold value less than or equal to preset th When the time is set, an alarm message is sent to remind the driver to perform braking operation, and the time is counted at the same time, if the collision time TTC is always detected within a set time period cr TTC (time to collision) threshold value less than or equal to preset th If the driver does not operate or the brake pedal is insufficient, an emergency brake executing instruction is sent out, and emergency brake is automatically executed.
The emergency brake execution instruction comprises brake deceleration information for executing emergency brake, and in the process of automatically executing the emergency brake, the emergency brake is braked according to the brake deceleration in the emergency brake execution instruction.
In the present embodiment, the set period of time is set to 0.2s, when the collision time TTC is detected for 0.2s cr TTC (time to collision) threshold value less than or equal to preset th And when the emergency braking is performed, an emergency braking execution instruction is sent to the braking execution mechanism module.
In the above-described process of executing the emergency braking, when it is detected that the vehicle continuously satisfies the condition of stopping the emergency braking for the set period of time, execution of the emergency braking is stopped. Wherein the meeting condition of stopping the emergency braking is that the speed of the vehicle is less than 1km/h or TTC cr TTC > preset time to collision threshold th Or a preset time to collision threshold TTC th > 4s (seconds).
According to the automatic emergency braking control method, according to the information of the obstacle existing on the road in front of the vehicle and the information of the vehicle, the collision time between the vehicle and the obstacle is calculated, different preset collision time thresholds are determined according to different vehicle speeds, logic judgment is carried out by comparing the collision time with the preset collision time thresholds, the graded braking control of different vehicle speeds is realized, the driving safety is ensured, and meanwhile, the riding comfort of passengers is greatly improved.
The steps involved in the second embodiment correspond to those of the first embodiment of the method, and the detailed description of the second embodiment can be found in the related description section of the first embodiment.
It will be appreciated by those skilled in the art that the modules or steps of the invention described above may be implemented by general-purpose computer means, alternatively they may be implemented by program code executable by computing means, whereby they may be stored in storage means for execution by computing means, or they may be made into individual integrated circuit modules separately, or a plurality of modules or steps in them may be made into a single integrated circuit module. The present invention is not limited to any specific combination of hardware and software.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
While the foregoing description of the embodiments of the present invention has been presented in conjunction with the drawings, it should be understood that it is not intended to limit the scope of the invention, but rather, it is intended to cover all modifications or variations within the scope of the invention as defined by the claims of the present invention.

Claims (7)

1. An automatic emergency brake control system, comprising: the system comprises a front road information sensing module, a vehicle information sensing module, an automatic emergency brake controller, an alarm module and a brake actuating mechanism module;
the front road information sensing module is used for acquiring front road information of a vehicle and sending the front road information to the automatic emergency brake controller in the running process of the vehicle; the forward road information includes a relative distance of a forward obstacle from the vehicle, a relative speed of the forward obstacle and the vehicle;
the vehicle information sensing module is used for acquiring vehicle information and sending the vehicle information to the automatic emergency brake controller in the running process of the vehicle; the vehicle information comprises a vehicle gear, a vehicle speed and an actual steering angle of the steering wheel;
the automatic emergency brake controller is used for receiving front road information and vehicle information of a vehicle in the running process of the vehicle, carrying out logic judgment according to the front road information and the vehicle information, outputting braking deceleration corresponding to the vehicle, sending an emergency brake executing instruction containing the braking deceleration to the brake executing mechanism module and sending an alarm signal to the alarm module;
the alarm module is used for sending out an alarm according to the alarm signal;
the brake executing mechanism module is used for receiving an emergency brake executing instruction and executing braking deceleration of corresponding deceleration according to the braking deceleration in the emergency brake executing instruction;
the logic judgment comprises the following steps:
judging whether to start automatic emergency braking control according to vehicle information: when the gear of the vehicle is the D gear, the speed is more than 0, and the actual turning angle of the steering wheel is less than 30 degrees, starting automatic emergency braking control, otherwise, not starting the automatic emergency braking control;
if the automatic emergency braking control is started, calculating the time required by collision between the vehicle and the front obstacle according to the relative distance between the front obstacle and the vehicle and the relative speed between the front obstacle and the vehicle;
determining a preset collision time threshold according to the current speed of the vehicle; the preset collision time threshold value is in direct proportion to the vehicle speed;
comparing the collision time with a preset collision time threshold, and when the collision time is more than the preset collision time threshold, not performing braking operation; when the collision time is less than or equal to a preset collision time threshold value, alarm information is sent out, timing is started at the same time, and if the collision time is detected to be less than or equal to the preset collision time threshold value within a set time period, an emergency braking execution instruction is sent out; the emergency brake execution instruction comprises a brake deceleration preset by executing emergency brake; the braking deceleration differs based on the current speed of the vehicle and/or the current collision time.
2. The automatic emergency brake control system according to claim 1, wherein the front road information sensing module comprises a front-view camera and a millimeter wave radar, the front-view camera takes the position of a lens as a coordinate origin, the running direction of a vehicle as an X-axis positive direction, and a counterclockwise direction perpendicular to the X-axis as a Y-axis positive direction, and a rectangular coordinate system is established;
based on the rectangular coordinate system, according to the road image in front of the vehicle acquired in real time by the forward-looking camera, the relative distance between the front obstacle and the vehicle and the relative speed between the front obstacle and the vehicle are calculated respectively by combining the ranging information output by the millimeter wave radar.
3. An automatic emergency brake control system according to claim 2, wherein the relative distance of the front obstacle from the vehicle is a distance in an X direction of the front obstacle with respect to the front view camera as an origin;
the relative speed of the front obstacle and the vehicle is a speed in the X direction of the front obstacle with respect to the front view camera as an origin.
4. The automatic emergency brake control system according to claim 1, wherein the brake actuator module issues an emergency brake stopping instruction when the automatic emergency brake controller detects that the vehicle continuously satisfies a condition for stopping the emergency brake for a set period of time during the emergency brake is performed;
the brake actuating mechanism module receives an emergency brake actuating stopping instruction, releases braking force and stops automatic braking.
5. An automatic emergency brake control system according to claim 4, wherein the condition for stopping emergency braking is that the vehicle speed is less than 1km/h or that the preset time is greater than the preset time threshold or that the preset time threshold is greater than 4s.
6. An automatic emergency brake control system according to claim 1, further comprising a self-test module for detecting whether each module of the automatic emergency brake control system is operating properly and transmitting self-test information to the automatic emergency brake controller.
7. An automatic emergency brake control method, characterized by comprising: after the vehicle is started, the automatic emergency braking control system is powered on for self-checking, and if no fault is detected, the automatic emergency braking control system enters a standby state;
opening an automatic emergency brake control system switch to enable the automatic emergency brake control system to enter an enabling state;
acquiring front road information and vehicle information of a vehicle; the front road information includes: a relative distance of a forward obstacle from the vehicle, a relative speed of the forward obstacle from the vehicle, the vehicle information including: vehicle gear, vehicle speed and steering wheel actual rotation angle;
logic judgment is carried out according to the front road information and the vehicle information, and corresponding automatic emergency braking operation is carried out according to a logic judgment result, specifically:
judging whether to start automatic emergency braking control according to vehicle information: when the gear of the vehicle is the D gear, the speed is more than 0, and the actual turning angle of the steering wheel is less than 30 degrees, starting automatic emergency braking control, otherwise, not starting the automatic emergency braking control;
if the automatic emergency braking control is started, calculating the time required by collision between the vehicle and the front obstacle according to the relative distance between the front obstacle and the vehicle and the relative speed between the front obstacle and the vehicle;
determining a preset collision time threshold according to the current speed of the vehicle; the preset collision time threshold value is in direct proportion to the vehicle speed;
comparing the collision time with a preset collision time threshold, and when the collision time is more than the preset collision time threshold, not performing braking operation; when the collision time is less than or equal to the preset collision time threshold value, alarm information is sent out, timing is started at the same time, and if the collision time is detected to be less than or equal to the preset collision time threshold value within the set time period, emergency braking is automatically executed according to preset braking deceleration.
CN202210842646.9A 2022-07-18 2022-07-18 Automatic emergency braking control system and method Active CN115158304B (en)

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