CN117622122A - Emergency braking operation method and device in ramp - Google Patents
Emergency braking operation method and device in ramp Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- 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
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- B60W30/09—Taking automatic action to avoid collision, e.g. braking and steering
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- B—PERFORMING OPERATIONS; TRANSPORTING
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Abstract
The invention discloses an emergency braking operation method in a ramp, which comprises the following steps: and (3) judging the vehicle position: judging whether the own vehicle is in a ramp or not, if so, continuing; coordinate conversion: acquiring position and pose information of an obstacle and lane line information on two sides, and performing coordinate transformation; target primary screening: primarily screening out obstacles which are unlikely to collide; target vehicle track following: fitting the motion condition of the target vehicle by adopting a constant turning rate and constant speed model; and (3) calculating collision time: adopting two-stage collision risk calculation; and (3) selecting a braking strategy: the collision time threshold ittc of the own vehicle is calibrated, the collision risk level of the vehicle is set according to the predicted collision time TTC1 and the real-time collision time TTC2, and a braking strategy is formulated. The invention also discloses an emergency braking operation device in the ramp. The invention expands the applicable scene of the AEB function, avoids the occurrence of collision accidents in the ramp, improves the safety of vehicle running, and can be widely applied to the intelligent automobile field.
Description
Technical Field
The invention relates to the field of intelligent automobiles, in particular to an emergency braking operation method and device in a ramp.
Background
With the increasing popularity of intelligent automobiles at present, L2+/L3-class vehicles are becoming more common in the market according to the SAE classification of automatic driving. The functions included therein are mainly: AEB (emergency braking assistance system), ACC (adaptive cruise system), LKA (lane keeping assistance system), ICA (intelligent pilot system), TLC (trigger lane change function), and the like. As is well known, safety is extremely important in assisting driving, and AEB is used as an automatic braking function in emergency, so that the traffic accident rate can be greatly reduced, and vehicles can be prevented from collision. The performance of the AEB function is therefore particularly important. Since most AEB functions are based on sensor measurement at present, the collision time between the vehicle and the obstacle in front is calculated, and whether the function is triggered is judged by comparing with a preset TTC. Therefore, AEB functions of most intelligent automobiles in the current market are only triggered under the condition that the automobiles keep straight or turn very little, and the functions are limited and cannot be triggered due to the fact that the prediction of the movement trend of the obstacle and the inaccurate calculation of collision points in a curve, particularly under the working condition similar to a ramp large curve, are not achieved.
Disclosure of Invention
The invention aims to overcome the defects of the background technology, and provides an emergency braking operation method and device in a ramp, which expand the applicable scene of an AEB function under the condition that the AEB emergency braking function gradually becomes a standard function in an intelligent automobile, cover the scenes of the ramp and a large curve, accurately predict the movement track of an obstacle in the ramp, fully consider the influence caused by steering of a self-vehicle, accurately calculate the collision risk of the self-vehicle and the obstacle, avoid the occurrence of collision accidents in the ramp and improve the running safety of the vehicle.
The invention provides an emergency braking operation method in a ramp, which comprises the following steps: and (3) judging the vehicle position: judging whether the current vehicle is in a ramp or not by using the information of high-precision map positioning or according to the lane line curvature information acquired by the camera, if so, entering a calculating and judging step, and if not, continuing to drive forwards; coordinate conversion: acquiring obstacle pose information and lane line information on two sides from a sensor, and performing coordinate transformation on the perception information; target primary screening: primarily screening out partial barriers which are unlikely to generate collision risks based on rules; target vehicle track following: fitting the motion condition of a target vehicle running continuously in a turning mode by adopting a constant turning rate and constant speed model, and predicting an original signal of the target vehicle obtained by a sensor under a Cartesian coordinate system; and (3) calculating collision time: respectively calculating corresponding predicted collision time TTCI and real-time collision time TTC2 by adopting two-stage collision risks; and (3) selecting a braking strategy: and calibrating collision time threshold value ittc of the self-vehicle under various speed conditions, setting collision risk level of the vehicle according to the magnitude relation among the predicted collision time TTC1, the real-time collision time TTC2 and the theoretical collision time ittc, and formulating a corresponding braking strategy.
In the above technical solution, the specific process of the coordinate transformation step is as follows: establishing a coordinate system: taking a vehicle lane central line as a reference line, and establishing a Frenet coordinate system by using a tangential vector and a normal vector of the reference line; obstacle projection distance parameter: the method comprises the steps of setting a point of a vehicle coordinate point projected to a Frenet coordinate system as an original point, projecting a transverse and longitudinal distance (x, y) of an obstacle to a reference line, and converting to obtain (s, d), wherein s is the distance between the obstacle and the vehicle in the direction of the reference line, and d is the distance between the obstacle and the vehicle in the direction perpendicular to the reference line; the vehicle on the lane is located at the position of the vehicle: based on the camera information, the position of the self-vehicle in the lane is obtained, namely the distances from the center of the self-vehicle to the lane lines on the left side and the right side respectively.
In the above technical solution, the coordinate transformation step further includes a substep of projection motion parameters of the obstacle, and the specific process is as follows: the method comprises the steps of setting a point of projection of an obstacle coordinate point to a Frenet coordinate system as an origin, respectively projecting the transverse and longitudinal speeds and accelerations of the obstacle to a lane central line, and converting the transverse and longitudinal speeds and accelerations of the obstacle in the lane central line direction.
In the above technical solution, the specific process of the target primary screening step is as follows: screening of obstacles in the longitudinal direction: screening out obstacles with a longitudinal distance s exceeding a longitudinal distance threshold and a longitudinal speed s' exceeding a longitudinal speed threshold; lateral direction obstacle screening: screening out obstacles of which the absolute value of the difference between the transverse distance d and the transverse distance from the vehicle to the central line of the lane exceeds a transverse distance difference threshold value and the transverse speed exceeds a transverse speed threshold value; distance parameter related obstacle screening: based on the obstacle sensing data obtained in the coordinate conversion step, sorting the longitudinal distances s from small to large, obtaining the obstacle information of the first three distances, and screening other obstacles; screening of obstacle types: based on the obstacle classification information obtained in the coordinate conversion step, the obstacles such as pedestrians, two-wheelers and tricycles are screened out.
In the above technical solution, the specific process of the target vehicle track tracking step is as follows: constant turn rate and constant speed model: the constant turn rate and constant speed model state equations are as follows: v k+1 ＝v k ，θ k+1 ＝θ k +w*dt，
wherein: x-longitudinal distance, y-transverse distance, v-vehicle speed, ψ -yaw angle, w-yaw rate; target vehicle motion information prediction: and predicting the motion information of the obstacle by using Kalman filtering to obtain the motion information of the target vehicle predicted by the kinematic model, wherein the motion information comprises the transverse and longitudinal distance, the transverse and longitudinal speed and the acceleration.
In the above technical solution, in the target vehicle track tracking step, the target vehicle motion information predicting sub-step further includes the following steps: the target vehicle motion information value is converted into a target vehicle motion information physical value under the Frenet coordinate system, namely the specific process is as follows: the method comprises the steps of setting a point of a target vehicle coordinate point projected to a Frenet coordinate system as an origin, projecting a transverse and longitudinal distance of the target vehicle to a lane central line, and converting to obtain a distance between the target vehicle and the vehicle in the direction of the lane central line and a distance between the target vehicle in the direction perpendicular to the lane central line; and taking a point of the target vehicle coordinate point projected to the Frenet coordinate system as an original point, respectively projecting the transverse and longitudinal speeds and the accelerations of the target vehicle to the lane central line, and converting to obtain the transverse and longitudinal speeds and the accelerations of the target vehicle in the lane central line direction.
In the above technical solution, the collision time calculating step adopts two-stage collision risk to calculate, and the specific process is as follows: longitudinal distance difference before and after the target vehicle delt_t time: calculating the position (x 1, y 1) of the own vehicle after the delt_t time according to the current steering wheel angle of the own vehicle, converting the position into the position (x 1', y 1') under the Frenet coordinate system, simultaneously, turning the target vehicle, predicting the track of the target vehicle based on the track tracking step of the target vehicle, calculating the new position of the target vehicle after the delt_t time, and calculating the longitudinal distance Dis_1 of the target vehicle after the delt_t time under the Frenet coordinate system; longitudinal distance of target vehicle to own vehicle at current moment: the specific process of calculating the longitudinal distance Dis_2 from the target vehicle to the own vehicle at the current moment is as follows: the predicted time to collision TTCI and the real time to collision TTC2 are calculated using the following formulas:wherein a is rel -longitudinal relative acceleration at the current moment, v rel -the current moment longitudinal relative speed, dis_1-the longitudinal distance of the target vehicle after the delt_t time, dis_2-the longitudinal distance of the target vehicle to the own vehicle at the current moment.
In the above technical solution, the specific process of the braking strategy selection step is as follows: presetting a collision time threshold ittc: calibrating collision time threshold ittc of the own vehicle under various speed conditions according to actual vehicle braking performance and reserved safety braking distance; selecting a braking scheme according to road conditions: when TTC1 is larger than TTC2, predicting that collision risk exists in a certain time in the future, when TTC1 is larger than ittc and larger than TTC2, the system state jumps from waiting to primary collision risk, a primary braking request is sent out, the deceleration is m1 until the collision risk with the target vehicle is not calculated by the vehicle, deceleration is canceled or a driver intervenes to step on the brake, and the system jumps to waiting; if ittc is less than TTC2, namely the system judges that the moment is in a very urgent moment, the system state jumps from 'primary collision risk' to 'secondary collision risk', a secondary braking request is sent, and the deceleration is m2, namely full-force braking; when TTC1 is smaller than TT2, the collision risk is lower in a future period, if ittc is larger than TTC1, the system does not send a deceleration request, and the system stays in a waiting state; if ittc is smaller than TTC1, the system state jumps from waiting to first-level collision risk, a first-level braking request is sent out, the deceleration is m1 until the own vehicle calculates that no collision risk exists with the front target vehicle, deceleration is canceled or a driver intervenes to step on the brake, and the system jumps to waiting.
In the above technical solution, in the step of selecting a braking strategy, the substep of selecting a braking strategy according to road conditions further includes a condition that the "delay state", i.e. "secondary collision risk", exits must be satisfied, and the specific process is as follows: when the secondary collision risk jumps to the waiting state, the delay T is required to be met, namely, after the vehicle is braked fully, the own vehicle and the target vehicle in front are free of risks, at the moment, the system state jumps from the secondary collision risk to the delay T state, the system continuously requests the deceleration m2, and after the delay reaches the time T, the delay T jumps to the waiting state, and the AEB emergency braking is completed.
The invention also provides an emergency braking operation device in the ramp, which is provided with a computer program, and the computer program can execute the emergency braking operation method in the ramp.
The emergency braking operation method and device in the ramp has the following beneficial effects:
the invention is prominently used in ramp scenes, avoids collision with a front target vehicle in emergency, reduces accident occurrence probability and improves vehicle running safety. And screening out AEB triggered candidate targets based on high-precision map information and information detected by a sensor, accurately predicting the moving track and possible collision time of the obstacle, introducing a novel TTC calculation method, and adopting a hierarchical braking strategy to ensure that the function is more intelligent and accurate.
Drawings
FIG. 1 is a schematic diagram of an overall flow of an emergency braking operation method in a ramp according to the present invention;
FIG. 2 is a schematic diagram of a state machine of step 6 in the emergency brake operation method of the ramp of the present invention;
FIG. 3 is a schematic diagram of an emergency brake operating device in the ramp according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, which should not be construed as limiting the invention.
Referring to fig. 1, the emergency braking operation method in the ramp of the invention comprises the following steps:
1. firstly, directly judging whether the current vehicle is in a ramp or not by using information of high-precision map positioning or according to lane line curvature information acquired by a camera, if so, entering a calculation and judgment stage, and if not, continuing to drive forwards.
2. The method comprises the following steps of obtaining obstacle pose information (speed, distance, acceleration, object classification, course angle and the like) and lane line information on two sides from a sensor, and converting the perceived information into coordinates, wherein the specific process is as follows:
taking the central line of the vehicle track as a reference line, and establishing a coordinate system, namely a Frenet coordinate system, by using a tangential vector and a normal vector of the reference line;
projecting a point of the vehicle coordinate point to the Frenet coordinate system as an origin, projecting a transverse and longitudinal distance (x, y) of the obstacle to the reference line, and converting to obtain (s, d), namely a distance s between the obstacle and the vehicle along the reference line and a distance d between the obstacle and the vehicle in a direction perpendicular to the reference line; similarly, the horizontal and longitudinal speeds and the acceleration of the obstacle are converted in the same way for later use in calculating collision risk;
based on the camera information, the position of the vehicle in the lane, namely the distance from the center of the vehicle to the lane lines on the left side and the right side, is obtained.
3. Target primary screening: the method is characterized by primarily screening out partial barriers which are unlikely to generate collision risk based on rules, wherein the specific process is as follows:
a) Screening out obstacles with a longitudinal distance(s) exceeding 20m and a longitudinal speed (s') exceeding 40 kph;
b) Screening out obstacles with the absolute value of the difference between the transverse distance (d) and the transverse distance from the vehicle to the central line of the lane exceeding 1m and the transverse speed exceeding 3 m/s;
c) Based on the obstacle sensing data obtained in the step 2, sorting s from small to large, obtaining obstacle information of the first three distances, and screening other obstacles;
d) Based on the obstacle classification information obtained in the step 2, targets such as pedestrians, two-wheelers and tricycles are screened out, and the target information is difficult to accurately obtain, so that the targets are removed, and the occurrence probability of functional errors is reduced.
4. Target vehicle track following: because the working condition is in the ramp, the target vehicle runs in a continuous turning, and the conventional uniform acceleration model cannot accurately fit the motion information of the target object, so that the motion condition of the target vehicle is fitted by adopting a constant turning rate and constant speed model, and the original signal (i.e. not converted in the step 2) of the target vehicle, which is acquired by a sensor, is predicted in a Cartesian coordinate system, and the specific process is as follows:
the constant turn rate and constant speed model state equations are as follows:
v k+1 ＝v k
θ k+1 ＝θ k +w*dt
wherein: x-longitudinal distance, y-transverse distance, v-vehicle speed, ψ -yaw angle, w-yaw rate;
predicting the motion information of the obstacle by using Kalman filtering to obtain the motion information of the target vehicle predicted by the kinematic model, wherein the motion information comprises transverse and longitudinal distance, transverse and longitudinal speed, acceleration and the like; in one or more embodiments, the target vehicle motion information values are converted to target vehicle motion information physical values in the Frenet coordinate system for use in subsequent calculations of collision risk, similar to step 2.
5. And (3) calculating collision time: in order to avoid discomfort brought to a driver by false triggering of emergency braking and ensure that the driver can brake under the emergency condition, the corresponding predicted collision time TTCI and real-time collision time TTC2 are calculated by adopting two-stage collision risks, and the specific process is as follows:
a) Calculating the position (x 1, y 1) of the own vehicle after a certain time delt_t (500 ms, which can be calibrated and is similar to the daily reaction time of a driver) according to the current steering wheel angle of the own vehicle, converting into (x 1', y 1') under the Frenet coordinate system, simultaneously, turning the target vehicle, calculating the new position of the target vehicle after the delt_t time based on the track prediction of the target vehicle in the step 4, and calculating the longitudinal distance Dis_1 of the target vehicle after the delt_t time under the Frenet coordinate system;
b) And calculating the longitudinal distance Dis_2 from the target vehicle to the own vehicle at the current moment.
The predicted time to collision TTCI and the real time to collision TTC2 are calculated using the following formulas:
wherein,
a rel -the current moment longitudinal relative acceleration;
v rel -the longitudinal relative speed at the current moment;
dis _ 1-longitudinal distance of the target vehicle after the delt _ t time,
dis_2-the longitudinal distance of the target vehicle to the own vehicle at the current moment;
the physical values are all physical values converted from a Cartesian coordinate system to a Frenet coordinate system.
6. And (3) selecting a braking strategy: calibrating collision time threshold value ittc of the self-vehicle under various speed conditions, setting collision risk level of the vehicle according to the magnitude relation among predicted collision time TTC1, real-time collision time TTC2 and theoretical collision time ittc, and formulating corresponding braking strategy, wherein the specific process is as follows (the specific state machine in the step is shown in figure 2):
the collision time threshold ittc is preset: calibrating theoretical collision time threshold value ittc of the own vehicle at different speeds according to actual vehicle braking performance (from an ADAS controller to ESC response execution deceleration) and reserved safety braking distance (about 0.5 m);
selecting a braking scheme according to road conditions: when TTC1>TTC2 indicates that collision risk is predicted in a certain time in the future, namely when the ITtc is between TTC2 and TTC1, the system state jumps from waiting to primary collision risk, a primary braking request is sent, and the deceleration is-4 m/s 2 Canceling deceleration or intervening by a driver to step on the brake until the system calculates that no collision risk exists with the front vehicle, and jumping the system to wait; if ittc<When TTC2 is adopted, namely the system judges that the moment is in very urgent state, the system state jumps from 'first-level collision risk' to 'second-level collision risk', a second-level braking request is sent, and the deceleration is-10 m/s 2 I.e. full force braking;
when TTC1<TTC2 indicates that the risk of collision will be low for a period of time in the future, if ittc>When TTC1 is adopted, the system does not send out a deceleration request and stays in a waiting state; if the collision time threshold value ittc is smaller than TTC1, the system state is changed from waiting to first-level collision risk, a first-level braking request is sent out, and the deceleration is-4 m/s 2 Canceling deceleration or intervening by a driver to step on the brake until the system calculates that no collision risk exists with the front vehicle, and jumping the system to wait;
in one or more embodiments, the vehicle further comprises a delay state, wherein the delay state is a condition which is required to be met by the exit of the second-level collision risk, so as to avoid transmission caused by the change of the self-body posture of the vehicle when the vehicle is braked at full forceThe sensor measurement information is inaccurate or the target tracking is lost, so that collision risk is calculated incorrectly, and the system jumps to the waiting state directly, so that when the second-level collision risk jumps to the waiting state, the delay T (1.5 s and can be calibrated) is required to be met, namely, after the vehicle is braked fully, the vehicle is free from risks with the target vehicle in front, at the moment, the system state jumps from the second-level collision risk to the delay T state, and the system continuously requests-10 m/s 2 After 1.5s, jump from "delay T" to "wait" and the wheel AEB emergency braking is completed.
Referring to fig. 3, the emergency brake operating device in the ramp of the present invention comprises the following parts:
the vehicle position judging module is used for: directly judging whether the current self-vehicle is in a ramp or not by using the information of the high-precision map, if so, entering a calculating and judging step, and if not, continuing to drive forwards;
and a coordinate conversion module: acquiring obstacle pose information and lane line information on two sides from a sensor, and performing coordinate transformation on the perception information;
and a target primary screening module: primarily screening out partial barriers which are unlikely to generate collision risks based on rules;
target vehicle track tracking module: fitting the motion condition of a target vehicle running continuously in a turning mode by adopting a constant turning rate and constant speed model, and predicting an original signal of the target vehicle obtained by a sensor under a Cartesian coordinate system;
the collision time calculation module is used for: respectively calculating corresponding predicted collision time TTCI and real-time collision time TTC2 by adopting two-stage collision risks;
a braking strategy selection module: and calibrating collision time threshold value ittc of the self-vehicle under various speed conditions, setting collision risk level of the vehicle according to the magnitude relation among the predicted collision time TTC1, the real-time collision time TTC2 and the theoretical collision time ittc, and formulating a corresponding braking strategy.
According to the invention, based on information such as a sensor, a high-precision map and the like, the movement trend and possible running track of the obstacle are estimated, the collision position of the vehicle and the obstacle is accurately calculated under the condition of steering of the vehicle, the collision risk of the vehicle and the obstacle is further calculated, and an emergency braking function is triggered when the risk exists, so that the collision is avoided.
The technical key points and the technical principle of the invention are as follows:
the key point of the invention is how to accurately and effectively calculate the collision risk with the obstacle in the curve scene. The physical value under the Cartesian coordinate system is converted into the physical value under the Frenet coordinate system, so that the calculation is more visual and controllable; adopting a reasonable screening strategy to remove invalid collision targets, and relieving the calculation pressure of the controller; considering that the obstacle is in the ramp, and also in the turning, fitting by using a proper kinematic equation, predicting the running track of the obstacle, and facilitating the following calculation; by adopting a novel TTC calculation method, setting two-stage TTCs and corresponding to different deceleration, the AEB performance is greatly improved by the design, on one hand, the probability of error occurrence is reduced, and on the other hand, timely intervention is performed when triggering is needed, so that collision avoidance is ensured.
Abbreviation and key term definitions
TTC: collision time;
ROI: a region of interest;
BCM: a vehicle body controller;
HMI: a human-machine interface;
V ego : speed of the vehicle.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
What is not described in detail in this specification is prior art known to those skilled in the art.
Claims (10)
1. An emergency braking operation method in a ramp is characterized in that: the method comprises the following steps: and (3) judging the vehicle position: judging whether the current vehicle is in a ramp or not by using the information of high-precision map positioning or according to the lane line curvature information acquired by the camera, if so, entering a calculating and judging step, and if not, continuing to drive forwards;
coordinate conversion: acquiring obstacle pose information and lane line information on two sides from a sensor, and performing coordinate transformation on the perception information;
target primary screening: primarily screening out partial barriers which are unlikely to generate collision risks based on rules;
target vehicle track following: fitting the motion condition of a target vehicle running continuously in a turning mode by adopting a constant turning rate and constant speed model, and predicting an original signal of the target vehicle obtained by a sensor under a Cartesian coordinate system;
and (3) calculating collision time: respectively calculating corresponding predicted collision time TTCI and real-time collision time TTC2 by adopting two-stage collision risks;
and (3) selecting a braking strategy: and calibrating collision time threshold value ittc of the self-vehicle under various speed conditions, setting collision risk level of the vehicle according to the magnitude relation among the predicted collision time TTC1, the real-time collision time TTC2 and the theoretical collision time ittc, and formulating a corresponding braking strategy.
2. The method of emergency braking operation in a ramp as defined in claim 1, wherein: the specific process of the coordinate conversion step is as follows:
establishing a coordinate system: taking a vehicle lane central line as a reference line, and establishing a Frenet coordinate system by using a tangential vector and a normal vector of the reference line;
obstacle projection distance parameter: taking the point of the own vehicle coordinate point projected to the Frenet coordinate system as the original point, projecting the transverse and longitudinal distances (x, y) of the obstacle to the reference line, converting to obtain (s, d),
wherein s is the distance between the obstacle and the vehicle in the direction of the reference line, and d is the distance between the obstacle and the vehicle in the direction perpendicular to the reference line;
the vehicle on the lane is located at the position of the vehicle: based on the camera information, the position of the self-vehicle in the lane is obtained, namely the distances from the center of the self-vehicle to the lane lines on the left side and the right side respectively.
3. The method of emergency braking operation in a ramp as defined in claim 2, wherein: the coordinate conversion step further comprises a substep of projection motion parameters of the obstacle, and the specific process is as follows:
the method comprises the steps of setting a point of projection of an obstacle coordinate point to a Frenet coordinate system as an origin, respectively projecting the transverse and longitudinal speeds and accelerations of the obstacle to a lane central line, and converting the transverse and longitudinal speeds and accelerations of the obstacle in the lane central line direction.
4. The method for emergency braking operation in a ramp as claimed in claim 3, wherein: the specific process of the target preliminary screening step is as follows:
screening of obstacles in the longitudinal direction: screening out obstacles with a longitudinal distance s exceeding a longitudinal distance threshold and a longitudinal speed s' exceeding a longitudinal speed threshold;
lateral direction obstacle screening: screening out obstacles of which the absolute value of the difference between the transverse distance d and the transverse distance from the vehicle to the central line of the lane exceeds a transverse distance difference threshold value and the transverse speed exceeds a transverse speed threshold value;
distance parameter related obstacle screening: based on the obstacle sensing data obtained in the coordinate conversion step, sorting the longitudinal distances s from small to large, obtaining the obstacle information of the first three distances, and screening other obstacles;
screening of obstacle types: based on the obstacle classification information obtained in the coordinate conversion step, the obstacles such as pedestrians, two-wheelers and tricycles are screened out.
5. The method for emergency braking operation in a ramp as defined in claim 4, wherein: the specific process of the target vehicle track tracking step is as follows:
constant turn rate and constant speed model: the constant turn rate and constant speed model state equations are as follows:
v k+1 ＝v k
θ k+1 ＝θ k +w*dt
wherein: x-longitudinal distance, y-transverse distance, v-vehicle speed, ψ -yaw angle, w-yaw rate;
target vehicle motion information prediction: and predicting the motion information of the obstacle by using Kalman filtering to obtain the motion information of the target vehicle predicted by the kinematic model, wherein the motion information comprises the transverse and longitudinal distance, the transverse and longitudinal speed and the acceleration.
6. The method for emergency braking operation in a ramp as defined in claim 5, wherein: in the target vehicle track tracking step, the target vehicle motion information predicting sub-step further includes the following steps:
the target vehicle motion information value is converted into a target vehicle motion information physical value under the Frenet coordinate system, namely the specific process is as follows:
the method comprises the steps of setting a point of a target vehicle coordinate point projected to a Frenet coordinate system as an origin, projecting a transverse and longitudinal distance of the target vehicle to a lane central line, and converting to obtain a distance between the target vehicle and the vehicle in the direction of the lane central line and a distance between the target vehicle in the direction perpendicular to the lane central line;
and taking a point of the target vehicle coordinate point projected to the Frenet coordinate system as an original point, respectively projecting the transverse and longitudinal speeds and the accelerations of the target vehicle to the lane central line, and converting to obtain the transverse and longitudinal speeds and the accelerations of the target vehicle in the lane central line direction.
7. The method of emergency braking operation in a ramp as defined in claim 6, wherein: the collision time calculation step adopts two-stage collision risks to calculate, and the specific process is as follows:
longitudinal distance difference before and after the target vehicle delt_t time: calculating the position (x 1, y 1) of the own vehicle after the delt_t time according to the current steering wheel angle of the own vehicle, converting the position into the position (x 1', y 1') under the Frenet coordinate system, simultaneously, turning the target vehicle, predicting the track of the target vehicle based on the track tracking step of the target vehicle, calculating the new position of the target vehicle after the delt_t time, and calculating the longitudinal distance Dis_1 of the target vehicle after the delt_t time under the Frenet coordinate system;
longitudinal distance of target vehicle to own vehicle at current moment:
the specific process of calculating the longitudinal distance Dis_2 from the target vehicle to the own vehicle at the current moment is as follows:
the predicted time to collision TTCI and the real time to collision TTC2 are calculated using the following formulas:
wherein,
a rel -the longitudinal relative acceleration at the present moment,
v rel -the longitudinal relative speed at the current moment,
dis _ 1-longitudinal distance of the target vehicle after the delt _ t time,
dis_2-longitudinal distance of the target vehicle to the host at the present moment.
8. The method of emergency braking operation in a ramp as defined in claim 7, wherein: the specific process of the braking strategy selection step is as follows:
presetting a collision time threshold ittc: calibrating collision time threshold ittc of the own vehicle under various speed conditions according to actual vehicle braking performance and reserved safety braking distance;
selecting a braking scheme according to road conditions: when TTC1 is larger than TTC2, predicting that collision risk exists in a certain time in the future, when TTC1 is larger than ittc and larger than TTC2, the system state jumps from waiting to primary collision risk, a primary braking request is sent out, the deceleration is m1 until the collision risk with the target vehicle is not calculated by the vehicle, deceleration is canceled or a driver intervenes to step on the brake, and the system jumps to waiting; if ittc is less than TTC2, namely the system judges that the moment is in a very urgent moment, the system state jumps from 'primary collision risk' to 'secondary collision risk', a secondary braking request is sent, and the deceleration is m2, namely full-force braking;
when TTC1 is smaller than TT2, the collision risk is lower in a future period, if ittc is larger than TTC1, the system does not send a deceleration request, and the system stays in a waiting state; if ittc is smaller than TTC1, the system state jumps from waiting to first-level collision risk, a first-level braking request is sent out, the deceleration is m1 until the own vehicle calculates that no collision risk exists with the front target vehicle, deceleration is canceled or a driver intervenes to step on the brake, and the system jumps to waiting.
9. The method of emergency braking operation in a ramp as defined in claim 8, wherein: in the step of selecting the braking strategy, the substep of selecting the braking strategy according to road conditions further comprises a condition that the 'delay state', namely the 'secondary collision risk', exits and must meet, and the specific process is as follows:
when the secondary collision risk jumps to the waiting state, the delay T is required to be met, namely, after the vehicle is braked fully, the own vehicle and the target vehicle in front are free of risks, at the moment, the system state jumps from the secondary collision risk to the delay T state, the system continuously requests the deceleration m2, and after the delay reaches the time T, the delay T jumps to the waiting state, and the AEB emergency braking is completed.
10. An emergency brake operating device in a ramp, having a computer program, characterized in that: the computer program is capable of executing the emergency braking operation method in a ramp as claimed in any one of claims 1 to 9.
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