CN117068134A

CN117068134A - Crossroad steering automatic braking system and method based on vehicle speed

Info

Publication number: CN117068134A
Application number: CN202310913333.2A
Authority: CN
Inventors: 许阁; 高航; 何佼容
Original assignee: Dongfeng Motor Group Co Ltd
Current assignee: Dongfeng Motor Group Co Ltd
Priority date: 2023-07-24
Filing date: 2023-07-24
Publication date: 2023-11-17

Abstract

The application provides a crossroad steering automatic braking method based on vehicle speed, which is based on the sectional calculation TTC of the vehicle speed of transverse and longitudinal decoupling and combines with an engineering calibration mode to realize the function of emergency braking of the vehicle at the crossroad. The method calculates the transverse and longitudinal TTC in a transverse and longitudinal decoupling mode based on relative vehicle speed subsection interpolation; and when the calculated transverse and longitudinal TTCs are within a calibrated TTC threshold range representing collision risk, indicating that the collision risk exists. According to the method, scene screening is carried out by simple motion analysis and one-dimensional parameter limitation, more accurate risk boundary points are selected by an engineering calibration method, and scenes in the boundary points are smoothed by segment interpolation based on different relative speeds; the algorithm model is simplified, the software load is reduced, and the accuracy can be increased by a test calibration method. The application has low load to the hard and software, and has portability.

Description

Crossroad steering automatic braking system and method based on vehicle speed

Technical Field

The application belongs to the technical field of automobile braking, and particularly relates to an automatic crossroad steering braking system and method based on vehicle speed.

Background

The crossroad scene is a complex traffic scene covering motor vehicles, non-motor vehicles and pedestrians, and is also a road section with easy traffic accidents. In the process of turning through the crossroad, if collision risk exists between the vehicle and the opposite vehicle, the collision is avoided or lightened in an emergency braking mode. In the existing implementation scheme, the running tracks of the host vehicle and the target vehicle are often selected to be predicted, and the collision risk is judged in a mode that whether track areas of the host vehicle and the target vehicle overlap or not.

For the calculation of the collision risk, one prior art employs that the dimensions of two carriages are represented by two circles according to the widths of the host vehicle and the target vehicle, two straight lines contacting the intersection are obtained from the two circles, the sum of the diameters of the two circles obtained not only with respect to the contact point of the two straight lines but also with respect to the center point of the width of the front surface of the host vehicle is set as a boundary, and when the angle of the motion vector of the host vehicle satisfies the boundary condition, the possibility of collision of the two carriages is judged. According to the technical scheme, a geometric mathematical model is adopted, so that the requirements on the model and the actual vehicle size and the fitting degree of the motion trend are high in risk judgment, and the modeling error in the modeling process can directly influence the judgment of the actual vehicle collision risk. The scheme is simply a geometric judgment method, the estimation of the gesture movement trend of the self-vehicle and the target vehicle is lacking, and the estimation of the gesture movement trend of the self-vehicle and the target vehicle is greatly influenced by the judgment of the actual collision risk.

Another prior art calculates a dangerous area of a target vehicle by based on parameters such as a shape speed of the target vehicle detected by the own vehicle. And then fitting and estimating the track of the future 2s of the vehicle according to the implementation track points of the vehicle. And when the estimated track falls into the dangerous area, the collision risk of the vehicle is indicated. The scheme has a clear mathematical basis which is provided by the scheme, and the real vehicle effect can be analyzed from top to bottom when the scheme is carried out on the vehicle. The mathematical method for judging collision risk is calculated by separating the dangerous area from the estimated estimation of the own vehicle, the influence of time factors is not considered, the own vehicle and the target vehicle are necessarily synchronous in time sequence, and the risk is judged according to whether the estimated track of the own vehicle is in the dangerous area or not, so that when the estimated point of time when the estimated track falls in the dangerous area possibly appears, the target vehicle is already driven away or the target vehicle is not waiting to approach, and the own vehicle is driven away from the dangerous area. According to the scheme, the historical track points are required to be processed in code implementation, and meanwhile, a region intersection method is adopted, so that the complexity of software implementation is increased.

Disclosure of Invention

The application aims to solve the technical problems that: an automatic crossroad steering braking system and method based on vehicle speed are provided for emergency braking of a vehicle at an crossroad.

The technical scheme adopted by the application for solving the technical problems is as follows: the crossroad steering automatic braking system based on the vehicle speed comprises a calibration observation management module, a perception information processing module, a state machine management module or a scene screening module, a risk calculation module and a control signal mapping module which are sequentially connected according to the signal flow direction; the state machine management module and the scene screening module are respectively connected between the perception information processing module and the risk calculation module; the calibration observation management module is used for defining the variable which needs to be set to be adjustable as a calibration quantity and defining the internal variable which needs to be observed in real time as an observed quantity; the perception information processing module is used for preprocessing a target object related signal output by the vehicle-mounted sensor; the state machine management module is used for classifying and judging according to the state which causes the function to enter into fault, forbidden or normal enabled state through the self-vehicle state related signal provided by the vehicle-mounted sensor, and reserving an extensible state; the state machine management module is also used for outputting a system state signal state and a function enabling signal enable as a state driving signal for subsequent risk calculation; the scene screening module is used for simplifying the function triggering range by limiting the series parameters of the vehicle and the target vehicle, including vehicle state screening and target object screening; the scene screening module also enables the function to realize the required triggering scene by adjusting the calibration parameters, and reduces false triggering of other scenes; the risk calculation module is used for judging whether the collision risk exists between the own vehicle and the target vehicle; the control signal mapping module is used for sending a calibratable deceleration clb _DecSet according to the result of whether collision risk exists or not judged by the risk calculation module, sending a deceleration interaction signal required by braking by matching with a speed reducer response logic of the vehicle type, and mapping the deceleration interaction signal to a vehicle-mounted bus control instruction so as to realize automatic braking of the vehicle.

According to the scheme, the vehicle-mounted sensor comprises a front camera, a front millimeter wave radar and a front angle radar.

According to the scheme, the preprocessing performed by the perception information processing module comprises classification group package and unit unification.

According to the scheme, the self-vehicle state related signals comprise vehicle speed, yaw rate and steering wheel rotation angle; the extensible states include a suppression state and an initialization state.

According to the scheme, the screening of the vehicle state comprises the following steps: the speed range of the self-vehicle at the low speed running of the crossroad is limited to be 5-30 km/h; limiting the steering wheel angle turned from the vehicle to the left to a certain calibratable positive number clb _w; defining the rotating speed of the steering wheel of the self-vehicle as a certain calibratable value clb _dw for distinguishing the intension degree of the driver controlling the vehicle;

target screening includes: limiting the longitudinal speed of the target object to a certain calibratable value clb _obj_vx, wherein the target object is used for screening out static or other scenes with self-defined vehicle speed; limiting the longitudinal distance of the target object relative to the vehicle to a certain calibratable value clb _obj_londis, and screening out inaccuracy of the sensor on the detection of the target object outside a longer distance; limiting the lateral distance of the target object relative to the vehicle to a certain calibratable value clb _obj_latsis for reducing false triggering at a longer distance; limiting the type of the target vehicle to a certain calibratable value clb _obj_type for customizing the type of a target object of which the selectable function can trigger braking;

and the object risk priority is defined, and the object risk priority is used for dividing the urgency degree of a plurality of objects detected by the sensor according to the transverse and longitudinal distance and the transverse and longitudinal speed, and selecting the most urgent object as the object of the subsequent processing.

According to the scheme, the risk calculation module comprises a speed grading module, a transverse and longitudinal TTC calculation module and a risk judgment module respectively connected with the output ends of the speed grading module and the longitudinal TTC calculation module.

A collision risk calculation method of an intersection steering automatic braking system based on vehicle speed comprises the following steps:

a calibratable clb _boundary relative speed comprising a minimum relative speed clb _relvelmin and a maximum relative speed clb _relvelmax is selected, and a lateral TTC threshold clb _ttclat, a longitudinal TTC threshold clb _ttclon, a lateral TTC threshold clb _ttclathhigh, a longitudinal TTC threshold clb _ttclonhigh, corresponding to the minimum relative speed clb _relvelmin, and a maximum relative speed clb _relvelmax;

setting test groups for a scene of the calibratable clb _boundary relative speed, and calculating the transverse collision time LatTTC and the longitudinal collision time LonTTC of the vehicle in real time;

according to whether the real vehicle collides or not and whether the braking effect is good, the corresponding transverse TTC threshold value and the corresponding longitudinal TTC threshold value are adjusted;

according to the determined boundaries clb _TTCLat, clb_TTCLon and clb_ TTCLatHigh, clb _TTCLonhigh, a corresponding transverse TTC threshold and a corresponding longitudinal TTC threshold are determined by adopting a linear interpolation method for scenes between clb _boundary relative speeds.

Further, when the test set is executed to set up the calibratable clb _boundary relative speed scenes respectively, the transverse collision time LatTTC and the longitudinal collision time LonTTC of the vehicle are calculated in real time, for the minimum relative speed scene,

triggering the bicycle brake if LatTTC < = clb _TTCLat and LonTTC < = clb _TTCLon;

if LatTTC < = clb _ttclat and LonTTC > clb _ttclan, increasing clb _ttclan by a calibration step clb _step 1;

if LatTTC > clb _ttclat and LonTTC < = clb _ttclat, increasing clb _ttclat by a calibration step clb _step 1;

if LatTTC > clb _TTCLat and LonTTC > clb _TTCLon, increasing the clb _TTCLat and clb _TTCLon according to the calibration step size clb _step1 and restarting the judgment;

when the coarse adjustment is performed faster, the initial value of the calibration step clb _step1 is set to 0.3.

Further, when the corresponding transverse TTC threshold and longitudinal TTC threshold are adjusted according to whether the real vehicles collide or not and whether the braking effect is good or not, if the longitudinal distance between the two vehicles after braking is larger than the clb _distance X threshold range and the transverse distance is larger than the clb _distance Y threshold range, the braking is judged to be earlier; otherwise, judging that the braking is late;

if the braking is earlier, clb _TTCLat and clb_TTCLon are reduced, a test group is set for a scene of the calibratable clb _boundary relative speed, and the transverse collision time LatTTC and the longitudinal collision time LonTTC of the vehicle are calculated in real time;

if braking is late, increasing clb _TTCLat and clb_TTCLon, executing test groups for the scenes of the calibratable clb _boundary relative speed, and calculating the transverse collision time LatTTC and the longitudinal collision time LonTTC of the vehicle in real time;

setting the step of increasing and decreasing to be a calibrated amount clb _step2; the initial value of the standard amount clb _step2 is set to 0.1, and is subsequently modified according to effects and experience.

Further, for the maximum relative speed scene, clb _ttclat is replaced by clb _ TTCLatHigh, clb _ttclat and clb _ttclathigh, a test set is set for the scene of the calibratable clb _boundary relative speed, the transverse collision time LatTTC and the longitudinal collision time LonTTC of the vehicle are calculated in real time, the corresponding transverse TTC threshold and the corresponding longitudinal TTC threshold are adjusted well according to whether the real vehicle collides or not and the braking effect is good, and a better transverse TTC threshold clb _TTclathigh and a longitudinal TTC threshold clb _TTCLonhigh are selected.

The beneficial effects of the application are as follows:

1. according to the crossroad steering automatic braking system and method based on the vehicle speed, TTC is calculated based on the segments of the vehicle speed in a transverse-longitudinal decoupling mode, and the emergency braking function of the vehicle at the crossroad is realized by combining an engineering calibration mode.

2. The application relates to a technical method for triggering emergency braking in a steering process. Calculating a transverse-longitudinal TTC (time to live) by simple one-dimensional data processing in a transverse-longitudinal decoupling mode based on relative vehicle speed segmentation interpolation; and when the calculated transverse and longitudinal TTCs are within a calibrated TTC threshold range representing collision risk, indicating that the collision risk exists.

3. The method is not based on a mathematical modeling method completely but based on a preset mathematical model completely, scene screening is carried out by combining one-dimensional parameter limitation (such as self-speed, rotation angle and other factors) through simple motion analysis, more accurate risk boundary points are selected through an engineering calibration method, and scenes in the boundary points are smoothed through piecewise interpolation based on different relative speeds. Therefore, the algorithm model is simplified, the software load is reduced, and the accuracy can be increased by a test calibration method.

4. The application has low requirement on hardware, and can be realized only by a camera, a front radar and a front angle radar; the software load is not high, the software calculation example is not high, and the problems of dead halt, overflow and the like caused by high-load operation of the controller are avoided; the application extracts a plurality of parameters into adjustable calibration quantity, and when changing different vehicle types, the application only needs to adapt and modify different vehicle configurations and calibration parameters.

Drawings

FIG. 1 is a scene diagram of an embodiment of the application.

Fig. 2 is a functional block diagram of an embodiment of the present application.

Fig. 3 is a flow chart of an embodiment of the present application.

Detailed Description

The application will be described in further detail with reference to the drawings and the detailed description.

Referring to fig. 1, embodiment 1 of the present application is a scene in which a vehicle turns left at an intersection and a collision risk occurs with a straight-ahead vehicle traveling in a left direction.

A functional block diagram of the present application is shown in fig. 2, and an embodiment of the present application includes the following modules:

and calibrating an observation management module. The module is used for defining the variable which needs to be set to be adjustable as a standard quantity, defining the internal variable which needs to be observed in real time as an observed quantity, and can be applied to various places of the software module to realize real-time adjustable and observable of the internal variable.

And a perception information processing module. The vehicle-mounted sensor comprises a front camera, a front millimeter wave radar, a front angle radar and other output target object related signals, and is subjected to pretreatment such as classification package, unit system and the like, so that the subsequent module is convenient to use.

And a state machine management module. The vehicle state related signals including the vehicle speed, the yaw rate, the steering wheel angle and the like provided by the vehicle sensor are classified and judged according to the states which can cause the function to enter into faults, enter into prohibition or enter into normal enabling and the like, and expandable states such as a suppression state, an initialization state and the like are reserved. The module outputs a system state signal state and a function enabling signal enable as state driving signals for subsequent risk calculation.

And a scene screening module. The module realizes the simplification of the function triggering range by limiting the series parameters of the own vehicle and the target vehicle, and can enable the function to realize the triggering scene shown in figure 1 and reduce false triggering of other scenes as much as possible by adjusting the calibration parameters of the module. Screening the state of the vehicle: limiting the speed range of the self-vehicle to 5-30km/h so as to meet the traffic rule that the crossroad should run at a low speed; limiting the steering wheel angle of the self-vehicle to a certain calibratable positive number clb _w so as to meet the scene of steering from the self-vehicle to the left; the rotation speed of the steering wheel of the self-vehicle is limited to a certain presettable value clb _dw, so that the intention intensity of the driver to control the vehicle is differentiated to a certain extent. Screening target objects: limiting the longitudinal speed of the target object to a certain calibratable value clb _obj_vx so as to screen out the static or other self-defined vehicle speed scenes of the target object; limiting the longitudinal distance of the target object relative to the vehicle to a certain calibratable value clb _obj_londis so as to screen inaccuracy of the sensor on detection of the target object outside a longer distance; limiting the lateral distance of the target object relative to the vehicle to a certain calibratable value clb _obj_latsis so as to reduce false triggering at a longer distance; limiting the type of the target vehicle to a certain calibratable value clb _obj_type so as to customize the type of a target object of which the selectable function can trigger braking; and dividing the risk priority of the target objects, dividing a plurality of target objects detected by the sensor according to the horizontal and longitudinal distance and the horizontal and longitudinal speed, and selecting the most urgent target object as a target object for subsequent processing.

The risk calculation module, the flow chart is shown in figure 3. Let the transverse TTC (time to collision) be the absolute value of the transverse distance of the target object relative to the own vehicle divided by the transverse velocity of the target object relative to the own vehicle; the longitudinal TTC is the absolute value of the longitudinal distance of the object relative to the vehicle divided by the longitudinal speed of the object relative to the vehicle.

a) The method comprises the steps of firstly selecting a calibratable clb _boundary relative speed and a corresponding boundary transverse-longitudinal TTC threshold value. The minimum relative speed clb _RelVelMin corresponds to the transverse and longitudinal TTC thresholds of clb _TTCLat and clb_TTCLon respectively, and the maximum relative speed clb _RelVelMax corresponds to the transverse and longitudinal TTC thresholds of clb _ TTCLatHigh, clb _TTCLonhigh respectively;

b) For a scene setting test group of two boundary relative speeds, calculating the transverse and longitudinal TTCs (LatTTC, lonTTC) of a vehicle in real time, for a minimum relative speed scene, if the LatTTC < = clb _ttclat and the LonTTC < = clb _ttclat, triggering the self-vehicle braking, if the LatTTC < = clb _ttclat and the LonTTC > clb _ttclan, increasing the clb _ttclat by a calibratable step clb _step1, if the LatTTC > clb _ttclat and the LonTTC < = clb _ttclan, increasing the clb _ttclat by a calibratable step clb _step1, if the LatTTC > clb _ttclat and the LonTTC > clb _ttclat, simultaneously increasing the clb _ttclat and the clb _ttclat by a calibratable step clb _step1 and re-performing the step b), and initially setting the clb _step1 to be 0.3;

c) And whether the corresponding transverse and longitudinal thresholds are well adjusted by whether the real vehicles collide or not and whether the braking effect is good or not. If braking is earlier (judged according to whether the longitudinal and transverse distances between two vehicles after braking are greater than the clb _distance X\Y threshold value range), clb _TTCLat and clb_TTCLon are reduced, returning to step b), if braking is later, clb _TTCLat and clb_TTCLon are increased, returning to step b), the step size of the increase reduction can be set to be a calibrated quantity clb _step2, default can be set to be 0.1, and later can be modified according to effects and experience to improve efficiency;

d) Repeating the steps of b) and c) to select a better transverse and longitudinal TTC threshold clb _ TTCLatHigh, clb _TTCLonhigh for the maximum relative speed scene, wherein clb _TTCLat is replaced by clb _TTCLathigh and clb _TTCLon is replaced by clb _TTCLonhigh in b) and c);

e) According to the determined boundaries clb _TTCLat, clb_TTCLon and clb_ TTCLatHigh, clb _TTCLonhigh, a linear interpolation method is adopted to determine the corresponding transverse and longitudinal TTC thresholds of the scenes between the boundary relative speeds clb _RelVelMin and clb _RelVelMax.

And a control signal mapping module. According to the risk calculation module, judging whether collision risk exists or not, the control signal mapping module sends a calibratable deceleration clb _DecSet, and sends a deceleration interaction signal required by braking in cooperation with a speed reducer response logic of a specific vehicle type, and maps a software internal deceleration request signal to a vehicle-mounted bus control instruction so as to realize automatic braking of the vehicle.

Embodiment 2 of the present application is a scenario in which a vehicle turns right at an intersection and a collision risk occurs with a straight-going vehicle facing the front right side. The procedure was the same as in example 1.

It should be understood that the sequence number of each step in the foregoing embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic, and should not limit the implementation process of the embodiment of the present application.

The above embodiments are merely for illustrating the design concept and features of the present application, and are intended to enable those skilled in the art to understand the content of the present application and implement the same, the scope of the present application is not limited to the above embodiments. Therefore, all equivalent changes or modifications according to the principles and design ideas of the present application are within the scope of the present application.

Claims

1. An intersection turns to automatic braking system based on speed of a motor vehicle, its characterized in that: the system comprises a calibration observation management module, a perception information processing module, a state machine management module or a scene screening module, a risk calculation module and a control signal mapping module which are sequentially connected according to a signal flow direction; the state machine management module and the scene screening module are respectively connected between the perception information processing module and the risk calculation module;

the calibration observation management module is used for defining the variable which needs to be set to be adjustable as a calibration quantity and defining the internal variable which needs to be observed in real time as an observed quantity;

the perception information processing module is used for preprocessing a target object related signal output by the vehicle-mounted sensor; the state machine management module is used for classifying and judging according to the state which causes the function to enter into fault, forbidden or normal enabled state through the self-vehicle state related signal provided by the vehicle-mounted sensor, and reserving an extensible state; the state machine management module is also used for outputting a system state signal state and a function enabling signal enable as a state driving signal for subsequent risk calculation;

the scene screening module is used for simplifying the function triggering range by limiting the series parameters of the vehicle and the target vehicle, including vehicle state screening and target object screening; the scene screening module also enables the function to realize the required triggering scene by adjusting the calibration parameters, and reduces false triggering of other scenes;

the risk calculation module is used for judging whether the collision risk exists between the own vehicle and the target vehicle;

the control signal mapping module is used for sending a calibratable deceleration clb _DecSet according to the result of whether collision risk exists or not judged by the risk calculation module, sending a deceleration interaction signal required by braking by matching with a speed reducer response logic of the vehicle type, and mapping the deceleration interaction signal to a vehicle-mounted bus control instruction so as to realize automatic braking of the vehicle.

2. A vehicle speed based crossroad steering automatic braking system as claimed in claim 1, wherein: the vehicle-mounted sensor comprises a front camera, a front millimeter wave radar and a front angle radar.

3. A vehicle speed based crossroad steering automatic braking system as claimed in claim 1, wherein: the preprocessing performed by the perception information processing module comprises classification group package and unit unification.

4. A vehicle speed based crossroad steering automatic braking system as claimed in claim 1, wherein: the vehicle state related signals comprise vehicle speed, yaw rate and steering wheel rotation angle;

the extensible states include a suppression state and an initialization state.

5. A vehicle speed based crossroad steering automatic braking system as claimed in claim 1, wherein:

the screening of the vehicle state comprises the following steps:

the speed range of the self-vehicle at the low speed running of the crossroad is limited to be 5-30 km/h;

limiting the steering wheel angle turned from the vehicle to the left to a certain calibratable positive number clb _w;

defining the rotating speed of the steering wheel of the self-vehicle as a certain calibratable value clb _dw for distinguishing the intension degree of the driver controlling the vehicle;

target screening includes:

limiting the longitudinal speed of the target object to a certain calibratable value clb _obj_vx, wherein the target object is used for screening out static or other scenes with self-defined vehicle speed;

limiting the longitudinal distance of the target object relative to the vehicle to a certain calibratable value clb _obj_londis, and screening out inaccuracy of the sensor on the detection of the target object outside a longer distance;

limiting the lateral distance of the target object relative to the vehicle to a certain calibratable value clb _obj_latsis for reducing false triggering at a longer distance;

limiting the type of the target vehicle to a certain calibratable value clb _obj_type for customizing the type of a target object of which the selectable function can trigger braking;

6. A vehicle speed based crossroad steering automatic braking system as claimed in claim 1, wherein:

the risk calculation module comprises a speed classification module, a transverse and longitudinal TTC calculation module and a risk judgment module respectively connected with the output ends of the speed classification module and the transverse and longitudinal TTC calculation module.

7. A collision risk calculation method of the vehicle speed-based intersection turning automatic braking system according to any one of claims 1 to 6, characterized by: the method comprises the following steps:

8. The collision risk calculation method according to claim 7, characterized in that:

when a test set is executed for respectively setting up a scalable clb _boundary relative speed scene, and the transverse collision time LatTTC and the longitudinal collision time LonTTC of the vehicle are calculated in real time, for the minimum relative speed scene,

9. The collision risk calculation method according to claim 8, characterized in that:

when the corresponding transverse TTC threshold and longitudinal TTC threshold are adjusted according to whether the real vehicles collide or not and whether the braking effect is good or not, if the longitudinal distance between the two vehicles after braking is larger than the clb _distance X threshold range and the transverse distance is larger than the clb _distance Y threshold range, the braking is judged to be early; otherwise, judging that the braking is late;

10. The collision risk calculation method according to claim 9, characterized in that: for the maximum relative speed scene, clb _TTCLat is replaced by clb _ TTCLatHigh, clb _TTCLon is replaced by clb _TTCLonhigh, a test set is set for the scene with the calibratable clb _boundary relative speed respectively, the transverse collision time LatTTC and the longitudinal collision time LonTTC of the vehicle are calculated in real time, the corresponding transverse TTC threshold and the corresponding longitudinal TTC threshold are adjusted well according to whether the vehicle collides or not and the braking effect is good, and the better transverse TTC threshold clb _TTCLathigh and the longitudinal TTC threshold clb _TTCLonhigh are selected.