CN110293967B - Low-speed active safety execution control method and system for automobile - Google Patents
Low-speed active safety execution control method and system for automobile Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
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- 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
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Abstract
The invention provides a control method and a system for an automobile low-speed active safety execution system, which are characterized in that a low-speed active safety execution system control strategy is designed, data information acquired by a short-distance ultrasonic radar and a look-around camera is acquired, surrounding environment information is detected, the problem of collision risk with an obstacle within 4 meters around the automobile is solved, data of two sensors are fused, the influence of gradient change on a distance value is considered, pressure building compensation is carried out on an initial pressure value of a braking force, the action intention of a driver is analyzed, the real-time operation behavior of the driver and the function of the low-speed emergency brake execution system control strategy are coordinated and controlled, the problem of driving active safety of the automobile in a low-speed state is solved, the stability of the active safety function of the automobile in the low-speed state is increased, and the safety reliability is improved.
Description
Technical Field
The invention belongs to the field of automobile electric appliances, and particularly relates to an active safety control strategy system in a low-speed state of a vehicle.
Background
In recent years, the demand of the automobile market in China for the active safety function in the low-speed driving state is increasing, vehicles in cities are increasing, and low-speed scenes of the vehicles appear very much in life, such as: the driving safety requirement of the vehicle in a low-speed state is increased in a congested road section, a parking process, a low-speed passing turnout and the like. Therefore, there is a need to propose an effective, reliable and more intelligent control strategy. Aiming at a low-speed driving state, a low-speed emergency brake execution system control strategy is provided.
At present, a plurality of schemes capable of providing an active safety collision avoidance system in the driving process have been proposed in the industry, and the schemes can realize the active safety function, reduce the occurrence of safety accidents and guarantee the safety of human and property. However, the current active safety system has some defects, the active safety is realized mainly by depending on the operation habit of a machine learning driver, the data volume is large, meanwhile, the characteristic range of the data is large, the accurate control of the whole vehicle cannot be achieved, and the system analysis is not performed under the condition of low speed of the vehicle. Active safety is realized through the motion state of the whole vehicle and the risk of acceleration and deceleration calculation, but the unified decision control on the operation of a driver and the low-speed active safety is not carried out, so that the active control risk and traffic accidents can be increased.
Disclosure of Invention
The invention provides a control method of a low-speed active safety execution system of an automobile, which mainly solves the driving active safety problem of the automobile in a low-speed state, increases the stability and improves the safety reliability aiming at the active safety function of the automobile in the low-speed state, collects data information collected by a short-distance ultrasonic radar and a look-around camera by designing a control strategy of the low-speed active safety execution system, detects the surrounding environment information, solves the problem of collision risk with an obstacle in a range of 4 meters around the automobile, fuses the data of two sensors, takes the influence of gradient change on a distance value into consideration, performs pressure building compensation on an initial pressure value of braking force, analyzes the action intention of a driver, and realizes the coordination control of the real-time operation behavior of the driver and the function of the control strategy of the low-speed emergency brake execution system.
The technical scheme of the invention is as follows:
the invention mainly detects and obtains the obstacle information around the vehicle through the ultrasonic radar and the looking-around camera, including the speed of the object and the distance relative to the vehicle, through the fusion of the ultrasonic radar (namely ultrasonic sensor) information and the looking-around camera information, the movement track of the obstacle is estimated, the obstacle distance is obtained, the braking distance is calculated through the speed feedback of the vehicle body, meanwhile, the unified coordination control is carried out by combining the real-time operation of the driver, the required values of different safety distances are solved, the braking state is logically judged, the pressure building time compensation is carried out through the initial pressure value, the braking time is determined, and the braking is executed.
Specifically, the control method of the present invention includes the steps of:
1. data acquisition: ultrasonic sensor detects an obstacle distance S around a vehicle1And the looking-around camera acquires the distance S of the obstacles around the vehicle2Acquiring the current gradient information of the running vehicle, the current real-time speed, the state of a brake pedal and the state of an accelerator pedal by a vehicle Body Controller (BCM) through a CAN bus;
2. data fusion: the low-speed emergency braking system controller processes the distance S of the obstacle detected by the ultrasonic sensor and the all-round camera1And S2Firstly fusing to obtain a primary fusion distance S'; then, according to the current gradient information of the running vehicle, calculating to obtain a gradient fusion distance S ″MeltFinally, the S 'and S' are combinedMeltObtaining the actual fusion distance value S of the vehicle and the barrier in the active safety area through fusionMelt；
3. And (3) determining the braking force and the braking time of the vehicle:
3.1, according to the current real-time speed, looking up a table to obtain the reserved safe distance S of the vehicle3；
3.2 according to SMeltAnd S3Calculating to obtain the braking position distance S, S ═ SMelt-S3；
3.3, using the formula
Calculating the braking time T' by a formula
Calculating to obtain a deceleration correction value alpha ', wherein V is the current vehicle speed, a is the target deceleration, V' is a speed change value and is obtained by controlling the change of the vehicle speed through the braking force, and delta T is a system sampling period;
3.4, the target deceleration a is corrected by the deceleration correction value a 'to obtain the target deceleration braking force F': obtaining a coefficient through table lookup, wherein the target deceleration braking force subtraction coefficient when alpha 'is larger than alpha, and the target deceleration braking force plus the coefficient when alpha' is smaller than alpha;
and 3.5, according to the states of the brake pedal and the accelerator pedal, compensating the target deceleration braking force F' by inquiring a brake pedal and accelerator state compensation braking force data table to obtain the actual execution braking force F.
4. Outputting braking force and braking time, and executing braking: judging whether the current braking is deceleration braking or emergency braking, selecting corresponding braking force, calculating braking time, carrying out pressure build-up time compensation on initial pressure values of the braking force of the deceleration braking and the emergency braking, obtaining final braking execution time T by looking up a table, judging that the braking force F is output after the braking execution time T is reached according to the T value and an execution force moment data table, and executing the braking.
Furthermore, the data fusion in step 2 of the invention is to use the azimuth distance information of the obstacle as the input value of the system, and the system plans the change track of the vehicle distance by predicting the movement track and state (static, steering, advancing and backing) of the obstacle, so as to obtain the distance SMeltThe method specifically comprises the following steps:
2.1, synchronizing coordinates and time of the two sensors: the coordinate synchronization is realized by converting the coordinate of the camera into a three-dimensional Cartesian coordinate with the center of the rear axle of the vehicle as an origin, converting the coordinate of the ultrasonic sensor into a two-dimensional Cartesian coordinate system with the center of the rear axle of the vehicle as the origin, synchronizing the coordinate systems and taking a point obtained by calculating the coordinate posture of the vehicle body as a basic synchronization environment coordinate point; the time synchronization adopts a controller to realize fusion, namely the distance S of the barrier acquired by the camera image is adopted2Time of and obstacle distance S acquired by ultrasonic waves1Respectively marking the time, and carrying out track synchronization on the time slice for calculation and processing.
2.2, fusing to obtain S': will S1And S2Fusing by a method of weighting and averaging to obtain an initial distance value S';
2.3, calculating to obtain a gradient fusion distance S ″Melt: calculating to obtain a gradient fusion distance S' according to the current gradient information of the running vehicleMeltFormula (ii)
Delta theta is the gradient of the current vehicle running;
2.4 obtaining the actual fusion distance S by fusionMelt：S`MeltThen weighting with S' to obtain the actual fusion distance SMelt；
In step 3, the brake braking force keeps partial pressure as initial pressure when the vehicle is in a low-speed state, and the pressure build-up time for completing the braking process of the whole vehicle under different initial pressures is different. And aiming at the deceleration pressure building process, a relation table of the initial pressure and the pressure building completion time is obtained through calibration. And aiming at the emergency braking process, obtaining a relation table between the initial pressure and the pressure build-up completion time through calibration. And decision control is carried out by combining the state information of a brake pedal and an accelerator of the vehicle and the running environment of the vehicle according to the brake state relation of the vehicle.
The invention further protects an automobile low-speed active safety execution control system for realizing the method, which comprises an ultrasonic sensor, a look-around camera, a low-speed emergency braking system controller and an automobile body controller BCM, wherein the ultrasonic sensor is connected with the low-speed emergency braking system controller through an L in bus, the look-around camera is connected with the low-speed emergency braking system controller through a coaxial digital signal line, and the low-speed emergency braking system controller is connected with the automobile body controller BCM through a CAN bus;
the system of the invention usually needs to arrange 12 ultrasonic radars and 4 high-definition cameras with 100 ten thousand pixels. The environmental information around the vehicle is detected through 12 vehicle-mounted ultrasonic sensors, the detection distance is 30 cm-450 cm, and 20 areas around the vehicle body are planned and distributed around the vehicle body.
The ultrasonic sensor used by the invention can continuously feed back the distance information of surrounding obstacles, and a two-dimensional point cloud map can be createdObtaining the distance S1Acquiring information of the front obstacle detected by the camera in real time, acquiring real-time position coordinates of the obstacle, type and speed of the obstacle and calculating a distance value S2。
By adopting the control strategy of the low-speed emergency brake execution system, the occurrence of safety accidents can be reduced, the economic property loss is reduced, the low-speed emergency brake system and the control of a driver are prevented from being prominent, the reliability of active safety is improved, the brake process of active braking is optimized, and the controllability of a vehicle is improved.
Drawings
FIG. 1. ultrasonic detection of obstacles diagram
FIG. 2 is a diagram of obstacles detected by the looking-around camera
FIG. 3 is an architecture diagram of a control strategy system for a low-speed emergency brake actuation system;
FIG. 4 is a flow chart of a control method of the low-speed active safety execution system.
Detailed Description
The present invention is further described in the following with reference to the drawings, and the technical solutions in the embodiments of the present invention are clearly and completely described. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1:
in the implementation of the invention, 12 ultrasonic sensors (ultrasonic radars) are arranged on the vehicle, the detection distance is 30cm to 450cm, and 20 areas around the vehicle body are planned and distributed around the vehicle body. The environmental information around the vehicle is detected by 12 ultrasonic sensors mounted on the vehicle.
As shown in fig. 1, the obstacle map detected by the ultrasonic sensor shows that a black car is a main car and a gray car is a detected target car, the ultrasonic sensor continuously detects the surrounding environment along with the forward movement of the car during the driving of the car, and when an obstacle is detected, ultrasonic waves are transmittedTime of over-received echo using the formula SDistance between＝(TFlying×VSound) Calculating the distance from the obstacle, TFlyingFor the time from the emission of the ultrasonic waves to the reception of the entire process, VSoundIs the propagation velocity of sound waves in air, SDistance betweenThe direct distance between the current ultrasonic sensor and the obstacle which detects the reflected sound echo is increased along with time to obtain a series of distance point clouds, black points in the image are detected 2D point clouds, the point clouds detect the regional outline of a target vehicle, the distance value of the outline closest to the main vehicle is obtained, and the distance value is the obstacle distance S obtained by ultrasonic waves1And the black arrow direction is the moving direction of the target vehicle.
Example 2:
in the implementation of the invention, 4 high-definition cameras with 100 ten thousand pixels are arranged on a vehicle, the front camera and the rear camera are respectively positioned on the front bumper and the rear bumper of the vehicle, and the left camera and the right camera are positioned below a rearview mirror of the vehicle during reversing.
As shown in fig. 2, the obstacle map detected by the look-around camera is shown, the black car is the main car, the gray car is the detected target car, and the look-around camera continuously captures information data of the surrounding environment during the running process of the vehicle. And processing the speed of 15 frames per second of the obtained image information, and extracting a moving object of the image by using an optical flow method. Utilizing SFM technology to extract features of objects in continuous images and adjust light beams to form sparse 3D point clouds, forming dense 3D point clouds when processed images reach a certain number, representing contour information of obstacles by black lines, analyzing target vehicle speed, the type of the obstacles and the nearest distance value of the contour to a main vehicle, namely the obstacle distance S acquired by a camera image2And the black arrow direction is the moving direction of the target vehicle.
Example 3:
the control strategy system architecture of the low-speed emergency brake execution system for realizing the method is shown in figure 3, wherein 12 ultrasonic input modules are connected with a low-speed emergency brake system controller through L in buses, a panoramic camera is connected with the low-speed emergency brake system controller through coaxial digital signal lines, and the low-speed emergency brake system controller is connected with a vehicle body controller BCM through a CAN bus, wherein the chips selected by the low-speed emergency brake system controller CAN be TI, TDA2X series, mainly TDA2S, TDA2P, TDA2E and the like.
Example 4:
the control flow of the present invention is shown in fig. 4, and mainly includes two parts, namely data input and policy output.
The data input part specifically comprises the following processes:
1. data acquisition: the ultrasonic sensor collects the environmental information around the vehicle, and the obtained obstacle distance S1The all-round looking camera acquires the information of obstacles around the vehicle, including the speed of the object and the distance relative to the vehicle, namely the obstacle distance S acquired by the camera image2. The gradient information of the current vehicle running is obtained by a vehicle Body Controller (BCM) through a CAN bus. Meanwhile, the current vehicle speed, the current gradient, the vehicle brake and the accelerator pedal state information are acquired.
2. Data fusion: the low-speed emergency brake controller processes the distance information of the obstacles detected by the ultrasonic sensor and the all-round camera and the current gradient information of the running vehicle, and the distance value S between the main vehicle and the obstacles in the active safety area is obtained by fusionMelt。
The data fusion specifically comprises:
2.1 coordinate and time synchronization of the two sensors:
and (3) coordinate synchronization: the coordinate of the camera is converted into a three-dimensional Cartesian coordinate with the center of the rear axle of the vehicle as an origin, the coordinate of the ultrasonic sensor is converted into a two-dimensional Cartesian coordinate system with the center of the rear axle of the vehicle as the origin, the coordinate systems are synchronized, and a point obtained by calculating the coordinate posture of the vehicle body is used as a basic synchronous environment coordinate point.
Time synchronization: the integration is realized by adopting a controller, and the barrier distance S acquired by the camera image is adopted2Time of and obstacle distance S acquired by ultrasonic waves1Respectively marking the time, and carrying out track synchronization on the time slice for calculation and processing.
2.2, obtaining a primary fusion distance S': will S1And S2And obtaining a distance value S' through fusion of a method of weighting and averaging. For example, in rainy weather, the distance value S detected by the ultrasonic sensor1The weighting of (c) is 48%. The illumination condition is good, and the distance value S detected by the camera is looked around2The weighting of (A) is 52%, and S' is obtained by calculation.
2.3, calculating to obtain a gradient fusion distance S ″Melt: according to the current gradient information of the running vehicle, S' is obtained by calculationMelt。
The grade information is represented by an elevation angle value, delta theta, for example a value of delta theta greater than a defined threshold value,
2.4 obtaining the actual fusion distance S by fusionMelt: namely, the S' isMeltThen weighting with S', e.g. S ″)MeltThe weighting of (a) is 3%;
S`＝48％*S1+52*S2
`Smelt＝97％*S+3％*SMelt。
The strategy output part comprises:
3. and (3) determining the braking force and the braking time of the vehicle:
S1and S2Through the fusion of a weighting averaging method, the weighting number of the sensor data of the panoramic camera is calibrated according to the illumination environment, and the weighting number is divided into three values, namely a large value, a medium value and a small value for different illumination intensities. The weighting number of the data obtained by the ultrasonic sensor is calibrated according to the states of rainy days and sunny days and is divided into three values, namely large value, medium value and small value. And fusing data of the two sensors to obtain a distance value S'. When the value of Δ θ is greater than a defined threshold, the effect of the ramp on the distance is considered, the effect of the angle is relatively small, and the weighting is small. Formula (II)
S`MeltThen weighting with S' to obtain fusion sum data SMelt。
Obtained by feedback of the state of the vehicle body, the state of backing a car and the state of advancingThe safe distance S that the vehicle can reserve is obtained by the feedback table look-up of the state and driving speed data3By the formula S ═ SMelt-S3Formula is adopted
S is the braking distance, V is the current vehicle speed, and the target deceleration a is obtained through calculation. Using formulas
And calculating the braking time T'. The change of the vehicle speed is controlled by the braking force to obtain the change value V' of the speed, the delta T is the system sampling period, and the deceleration correction value is obtained
The target deceleration a is corrected by the deceleration correction value a 'to obtain the target deceleration braking force F'. And (3) performing table look-up compensation on the braking force by combining the vehicle braking state relation with the state information of a vehicle brake pedal and an accelerator and the driving environment of the vehicle to obtain the braking force F, and obtaining the deceleration brake and the emergency brake due to different magnitudes of the braking force.
The method comprises the following specific steps:
3.1, according to the current real-time vehicle speed, searching and obtaining the reserved safe distance S of the vehicle in a reserved safe distance data table (a data table obtained by calculating or summarizing empirical data obtained by a developer in the development process)3；
3.2 according to SMeltAnd S3Calculating to obtain the braking position distance S, S ═ SMelt-S3；
3.3, using the formula
Calculating the braking time T' by a formula
Calculating to obtain a deceleration correction value alpha ', wherein V is the current vehicle speed, a is the target deceleration, and V' is obtained as a speed change valueThe change of the braking force control vehicle speed is obtained, and delta T is a system sampling period;
3.4, the target deceleration a is corrected by the deceleration correction value a 'to obtain the target deceleration braking force F': obtaining a coefficient by looking up a table (or a table obtained by calculating or summarizing empirical data obtained by a developer during development), wherein α 'is greater than the α -time target deceleration braking force subtraction coefficient, and α' is less than the α -time target deceleration braking force addition coefficient;
and 3.5, according to the states of the brake pedal and the accelerator pedal, compensating the target deceleration braking force F' by inquiring a brake pedal and accelerator state compensation braking force data table to obtain the actual execution braking force F.
4. Outputting braking force and braking time, and executing braking:
judging whether the current braking is deceleration braking or emergency braking, selecting corresponding braking force, and calculating the braking time. The method comprises the following steps:
4.1, judging whether the deceleration brake is performed, if so, selecting corresponding braking force, and obtaining the pressure-building compensation time T during the deceleration brake by inquiring a deceleration brake pressure-building compensation time data table1Carrying out pressure building time compensation on an initial pressure value of the braking force of the deceleration brake to obtain brake execution time T;
4.2, if not, selecting corresponding braking force for emergency braking, and obtaining the time T of pressure build-up compensation during emergency braking by inquiring the data table of the pressure build-up compensation time of the emergency braking2And carrying out pressure building time compensation on the initial pressure value of the braking force of the emergency brake to obtain the brake execution time T.
And 4.3, judging to output actual execution braking force F after the brake execution time T is reached according to the T value execution force time data table, and executing the brake.
Finally, it is noted that the above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (5)
1. A control method for a low-speed active safety execution system of an automobile comprises the following steps:
(1) data acquisition: ultrasonic sensor detects an obstacle distance S around a vehicle1And the looking-around camera acquires the distance S of the obstacles around the vehicle2Acquiring the current vehicle running gradient information, real-time vehicle speed, brake and accelerator pedal states by a vehicle Body Controller (BCM) through a Controller Area Network (CAN) bus;
(2) data fusion: the low-speed emergency braking system controller processes the distance S of the obstacle detected by the ultrasonic sensor and the all-round camera1And S2Firstly fusing to obtain a primary fusion distance S'; then, according to the current gradient information of the running vehicle, calculating the gradient fusion distance S ″MeltFinally, the S 'and S' are combinedMeltObtaining the actual fusion distance value S of the vehicle and the barrier in the active safety area through fusionMelt；
(3) And (3) determining the braking force and the braking time of the vehicle:
(3.1) according to the current real-time speed, looking up a table to obtain the reserved safe distance S of the vehicle3；
(3.2) according to SMeltAnd S3Calculating to obtain a braking position distance S;
(3.3) Using the formula
Calculating the braking time T' by a formula
Calculating to obtain a deceleration correction value alpha ', wherein v is the current vehicle speed, a is the target deceleration, v ' is a speed change value, the deceleration correction value alpha ' is obtained by controlling the change of the vehicle speed through the braking force, and delta T is a system sampling period;
(3.4) target deceleration braking force F 'is obtained by correcting target deceleration a with deceleration correction value a': obtaining a coefficient through table lookup, wherein the target deceleration braking force subtraction coefficient when alpha 'is larger than alpha, and the target deceleration braking force plus the coefficient when alpha' is smaller than alpha;
(3.5) compensating the target deceleration braking force F' by inquiring a brake pedal and accelerator state compensation braking force data table according to the states of the brake pedal and the accelerator pedal to obtain an actual execution braking force F;
(4) outputting braking force and braking time, and executing braking: judging whether the current braking is the deceleration braking or the emergency braking, selecting corresponding braking force, calculating braking time, performing pressure build-up time compensation on initial pressure values of the braking force of the deceleration braking and the emergency braking, obtaining final braking execution time T by looking up a table, judging whether the actual execution braking force F is output after the braking execution time T is reached according to the T value and an execution force moment data table, and executing the braking.
2. The control method of the low-speed active safety execution system of the automobile according to claim 1, wherein the data fusion specifically comprises:
(2.1) coordinate and time synchronization of the two sensors: the coordinate synchronization is realized by converting the coordinate of the camera into a three-dimensional Cartesian coordinate with the center of the rear axle of the vehicle as an origin, converting the coordinate of the ultrasonic sensor into a two-dimensional Cartesian coordinate system with the center of the rear axle of the vehicle as the origin, synchronizing the coordinate systems and taking a point obtained by calculating the coordinate posture of the vehicle body as a basic synchronization environment coordinate point; the time synchronization is to adopt an obstacle distance S acquired by a looking camera2Time of and obstacle distance S acquired by the ultrasonic sensor1Respectively marking the time, and carrying out track synchronization on the time slice for calculation and processing;
(2.2) fusion to obtain the primary fusion distance S': will S1And S2Fusing by a weighted averaging method to obtain a distance value S';
(2.3) calculating to obtain a gradient fusion distance S ″Melting:calculating to obtain the slope blending according to the current slope information of the running of the vehicleClose distance SMeltFormula (ii)
Delta theta is the elevation angle value of the gradient of the current vehicle;
(2.4) obtaining the actual fusion distance S by fusionMelt：S`MeltThen weighting the distance S' to obtain the actual fusion distance SMelt。
3. The control method of the active safety execution system at low speed of automobile according to claim 1, wherein the emergency braking and the deceleration braking in the step (4) are two different braking states, and are used for judging the pressure build-up selection, specifically:
when the deceleration brake is judged to be currently performed, selecting corresponding braking force, and performing T on the deceleration brake by inquiring the data table of the pressure build-up compensation time of the deceleration brake1Pressure build-up compensation to obtain a brake execution time T, wherein T1The pressure build-up compensation time is used for deceleration braking;
when the emergency brake is judged, selecting corresponding brake force, and performing T on the emergency brake by inquiring the emergency brake pressure build-up compensation time data table2Pressure build-up compensation to obtain a brake execution time T, wherein T2The pressure build-up compensation time during emergency braking is obtained.
4. The control method of active safety execution system at low speed of automobile according to claim 1,
the system comprises at least 12 ultrasonic sensors, an ultrasonic input module, a panoramic camera and a low-speed emergency braking system controller, wherein the ultrasonic sensors are arranged to detect environmental information around a vehicle, the detection distance is 30-450 cm, 20 areas around the vehicle body are planned and distributed around the vehicle body, the ultrasonic input module is connected with the low-speed emergency braking system controller through an L in bus, and the panoramic camera is connected with the low-speed emergency braking system controller through a coaxial digital signal line.
5. The automobile low-speed active safety execution control system for realizing the method of claim 1 comprises an ultrasonic sensor, a look-around camera, a low-speed emergency braking system controller and an automobile body controller BCM, and is characterized in that the ultrasonic sensor is connected with the low-speed emergency braking system controller through an L in bus, the look-around camera is connected with the low-speed emergency braking system controller through a coaxial digital signal line, and the low-speed emergency braking system controller is connected with the automobile body controller BCM through a CAN bus;
the ultrasonic sensor is used for detecting the distance S of the obstacle around the vehicle1The all-round looking camera is used for acquiring the distance S of obstacles around the vehicle2；
The low-speed emergency brake system controller comprises a data input module and a strategy output module; the data of the input module is generated by an external sensor and is sent to the low-speed emergency braking system controller through a bus;
the data input module comprises a data acquisition unit and a data fusion unit;
the data acquisition unit is used for acquiring the distance S of the obstacles detected by the ultrasonic sensor and the all-round camera1And S2Acquiring current vehicle running gradient information, current real-time vehicle speed, and states of a brake pedal and an accelerator pedal;
the data fusion unit is used for processing the distance S of the obstacles detected by the ultrasonic sensor and the all-round camera1And S2Firstly fusing to obtain a primary fusion distance S'; then, according to the current gradient information of the running vehicle, S' is obtained by calculationMeltFinally, the S 'and S' are combinedMeltFusing to obtain the actual distance value S between the vehicle and the barrier in the active safety areaMelt；
The strategy output module comprises a decision unit and an output unit;
the decision unit is used for deciding the braking force and the braking time of the vehicle and comprises the following components:
according to the current real-time speed, looking up a table to obtain the reserved safe distance S of the vehicle3；
According to SMeltAnd S3Calculating to obtain a braking position distance S;
using formulas
Calculating the braking time T' by a formula
Calculating to obtain a deceleration correction value alpha ', wherein V is the current vehicle speed, a is the target deceleration, V ' is a speed change value, the deceleration correction value alpha ' is obtained by controlling the change of the vehicle speed through the braking force, and delta T is a system sampling period;
target deceleration braking force F 'obtained by correcting target deceleration a with deceleration correction value a': obtaining a coefficient through table lookup, wherein the target deceleration braking force subtraction coefficient when alpha 'is larger than alpha, and the target deceleration braking force plus the coefficient when alpha' is smaller than alpha;
compensating the target deceleration braking force F' by inquiring a brake pedal and accelerator state compensation braking force data table according to the states of a brake pedal and an accelerator pedal to obtain an actual execution braking force F;
the output unit is used for outputting braking force and braking time and executing braking: judging whether the current braking is the deceleration braking or the emergency braking, selecting corresponding braking force, calculating braking time, performing pressure build-up time compensation on initial pressure values of the braking force of the deceleration braking and the emergency braking, obtaining final braking execution time T by looking up a table, judging whether the actual execution braking force F is output after the braking execution time T is reached according to the T value and an execution force moment data table, and executing the braking.
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| CN111241224B (en) * | 2020-01-10 | 2021-05-11 | 福瑞泰克智能***有限公司 | Method, system, computer device and storage medium for target distance estimation |
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| CN112455443B (en) * | 2020-11-12 | 2022-01-28 | 复旦大学 | Vehicle active braking system based on multi-sensor fusion |
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