Rear transverse passing early warning control method based on electronic rearview mirror

Abstract

The invention discloses a rear transverse passing early warning control method based on an electronic rearview mirror. The method comprises the steps that the electronic rearview mirror is powered on to complete initialization; a real-time image behind the vehicle is displayed in the electronic rearview mirror; the electronic rearview mirror obtains a vehicle body signal and analyzes a vehicle gear signal tg, a vehicle speed V1, a vehicle transverse acceleration a1h, a vehicle longitudinal acceleration a1v, a vehicle state status1 and a steering wheel angle steerangle; the electronic rearview mirror carries out view adjustment according to the vehicle gear signal tg, and when the vehicle gear signal tg is a reverse gear, the electronic rearview mirror displays a reverse temporary view; detecting whether a transverse passing target exists in a reversing temporary visual field, if so, calculating an early warning time threshold value TTCmin, and determining an RCTA early warning area; and when the RCTA early warning condition is met, an RCTA early warning mark is output, and when the brake control signal sending condition is met, the electronic rearview mirror sends a brake control signal to the vehicle, so that the vehicle is decelerated and stopped. According to the invention, the early warning area of the RCTA can be dynamically adjusted for reasonable early warning control according to the backing posture of the vehicle.

Description

Technical Field

[0001] The invention relates to the field of vehicle control, and in particular to a control method for rear lateral crossing warning based on an electronic rearview mirror. Background Art

[0002] Rear Cross Traffic Alert (RCTA) is a driving assistance function that warns the driver of oncoming vehicles on both sides when reversing. At present, most existing technologies use reversing radar / rearview camera + ADAS controller + central control screen to realize RCTA function, but the reversing radar does not have the image display function. Although the rearview camera can display the reversing image, the field of view is very small and cannot meet the accuracy requirements of RCTA. If it is changed to a camera with a large field of view, the cost will increase. The use of image output height and depth heat map to determine whether to trigger RCTA warning lacks the prediction of the distance between the vehicle and the target at the future moment. When a collision occurs, it is difficult for the driver to avoid it in time. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a control method for rear lateral crossing warning based on an electronic rearview mirror, which realizes rear lateral crossing warning of the vehicle based on the electronic rearview mirror, and can timely remind technicians of potential reversing collision risks without increasing hardware costs.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a control method for rear lateral crossing warning based on an electronic rearview mirror, comprising the following steps:

[0005] S1, the vehicle is started, and the electronic rearview mirror is powered on and initialized;

[0006] S2, the electronic rearview mirror displays a real-time image of the rear of the vehicle;

[0007] S3, the electronic rearview mirror obtains the vehicle body signal and analyzes the vehicle gear signal tg, the vehicle speed V1, the vehicle lateral acceleration a 1h , the longitudinal acceleration of the vehicle a 1v , vehicle status status1 and steering wheel angle steer angle ;

[0008] S4, the electronic rearview mirror adjusts the field of view according to the vehicle gear signal tg, and when the vehicle gear signal tg is the reverse gear, the electronic rearview mirror displays the temporary reverse field of view;

[0009] S5. Detect whether there is a horizontally moving target in the temporary reversing field of view. If so, calculate the warning time threshold TTC min , and determine the RCTA warning area;

[0010] S6. When the RCTA warning condition is met, an RCTA warning sign is output to remind the driver;

[0011] S7. When the brake control signal sending condition is met, the electronic rearview mirror sends a brake control signal to the vehicle, causing the vehicle to decelerate and stop.

[0012] Furthermore, when detecting whether there is a lateral target in the temporary reversing field of view, the parameters obtained include: the angle θ between the extension line of the vehicle body and the lateral extension line of the curb, the target category, the target moving direction, the target state, the target moving speed V2, the target lateral acceleration a 2h , target longitudinal acceleration a 2v , the lateral distance L1 between the target and the rear of the vehicle, and the longitudinal distance L2 between the target and the rear of the vehicle.

[0013] Furthermore, the RCTA warning areas were determined, including:

[0014] When the angle θ between the extended line of the vehicle body and the lateral extended line of the curb is 90°, the RCTA warning area is the area surrounded by ABCD and the area surrounded by EFGH. The area surrounded by EFGH is symmetrical with the area surrounded by ABCD along the longitudinal center line of the vehicle body.

[0015] The coordinates of point A are (x A ,y A )=(L mn / 2,0),

[0016] The coordinates of point B are (x B ,y B )=(L mn / 2+L HFOV ,0),

[0017] The coordinates of point C are (x C ,y C )=(L mn / 2+L HFOV ,-L),

[0018] The coordinates of point D are (x D ,y D )=(L mn / 2,-L),

[0019] L mn represents the width of the vehicle, L represents the maximum distance from the rear of the vehicle that the electronic rearview mirror can cover, and L HFOV Indicates the maximum distance of the FOV that the electronic rearview mirror can cover.

[0020] Furthermore, the RCTA warning areas were determined, including:

[0021] When the angle θ between the extended line of the vehicle body and the lateral extended line of the curb is less than 90°, the RCTA warning area is the area enclosed by A'B'C'D', the area enclosed by E'F'G'H' and the area enclosed by I'J'B'K'. The area enclosed by E'F'G'H' is symmetrical with the area enclosed by A'B'C'D' along the longitudinal center line of the vehicle body. The area enclosed by I'J'B'K' is the area between the lateral extended line of the curb and the area enclosed by A'B'C'D'.

[0022] The coordinates of point A' are (x A' ,y A' )=(L mn / 2,0),

[0023] The coordinates of point B' are (x B' ,y B' )=(L mn / 2+L HFOV ·sinθ,-L HFOV ·cosθ),

[0024] The coordinates of point C' are

[0025]

[0026] The coordinates of point D' are (x D' ,y D' )=(-L·cosθ+L mn / 2,-L·sinθ),

[0027] The coordinates of point I' are (x I' ,y I' )=(L BSD / sinθ,0),

[0028] The coordinates of point K' are (x K' ,y K' )=(L BSD ·sinθ,-L BSD ·cosθ),

[0029] The coordinates of point J' are

[0030] (x J' ,y J' )=((L mn ·Len·sinθ+L mn ·L HPOV ·cosθ+2Len·L HFOV ) / 2(Len·sinθ+L HFOV ·cosθ),0)

[0031] The coordinates of point E' are (x E' ,y E' )=(L mn / 2-L mn ·sinθ,L mn ·cosθ),

[0032] The coordinates of point F' are

[0033] (x F' ,y F' )=(L mn / 2-L mn / sinθ-L·cosθ+L mn ·cotθ·cosθ,-(LL mn ·cotθ)·sinθ),

[0034] The coordinates of point G' are

[0035] (x G' ,y G' )=(-L mn / sinθ-L HFOV / sinθ+L mn / 2-L·cosθ+L mn ·cotθ·cosθ+L HFOV ·cotθ·cosθ,-L·sinθ+L mn ·cosθ+L HFOV ·cosθ)

[0036] The coordinates of point H' are (x H' ,y H' )=(L mn / 2-(L mn +L HFOV )·sinθ,(L mn +L HFOV )·cosθ),

[0037] Len represents the distance between the installation position of the electronic rearview mirror and the rear of the vehicle. BSD Indicates the maximum lateral warning distance of the vehicle's BSD.

[0038] Further, calculate the warning time threshold TTC min ,include:

[0039] Calculate the lateral warning time as TTC h =2L1 / (2V1+a 1h 2 +2V2+a 2h 2 ),

[0040] Calculate the longitudinal warning time as TTC v =2L2 / (2V1+a 1v 2 +2V2+a 2v 2 ),

[0041] Warning time threshold TTC min = min(TTC h ,TTC v ).

[0042] Furthermore, the RCTA warning conditions include: the vehicle gear signal tg is the reverse gear, there is a horizontally moving target within the detection range, the target is within the RCTA warning area, and the collision time TTC <

[0043] TTC min ; When all the above conditions are met, the RCTA warning sign is output.

[0044] Furthermore, the brake control signal is output according to the minimum safety distance and the collision time TTC. 1min Or real-time longitudinal distance < L 2min Or when TTC is less than 2s, the brake control signal is triggered and sent to the vehicle. 1min Indicates the minimum lateral distance, L 2min Indicates the minimum vertical distance.

[0045] Furthermore, when the angle between the extended line of the vehicle body and the lateral extended line of the curb is θ=90°,

[0046] Real-time lateral distance L 1t =L1-(V1·T RCTA +a 1v 2 ·T RCTA / 2)-(V2·T RCTA +a 2v 2 ·T RCTA / 2),

[0047] Real-time longitudinal distance L 2t =L2-a 1h 2 ·T RCTA / 2-a 2h 2 ·T RCTA / 2,

[0048] T RCTA is the predicted reversing time.

[0049] Furthermore, when the angle θ between the extended line of the vehicle body and the lateral extended line of the curb is less than 90°,

[0050] The real-time horizontal distance is

[0051] L 1t =L1-(K1·V1·T RCTA +K2·V1 2 ·sin(steer angle / k steer )·T RCTA / L3)

[0052] -(K3·V2·T RCTA +K4·a 2v 2 ·T RCTA / 2),

[0053] The real-time vertical distance is

[0054] L 2t =L2-K5·V1 2 ·sin(steer angle / k steer )·T RCTA / L3-K6·a 2v 2 ·T RCTA / 2,

[0055] L3 represents the wheelbase of the vehicle, k steer Indicates the ratio of the steering wheel angle to the front wheel angle. K1, K2, K3, K4, K5, and K6 are correction coefficients. T RCTA is the predicted reversing time.

[0056] Furthermore, when the vehicle receives a brake control signal, the deceleration of the vehicle is:

[0057] B pectReq_out (t) = K·B pectReq (t)+(1-K)·B pectReq (t-1),

[0058] Among them, B pectReq (t) = K brake ·a 1target (t),

[0059] a 1target (t) = min[(-V1 2 / (2L 2t -2L safe )-a 1v ),(-V1 / T brake -a 1v )],

[0060] T barke Indicates the time to complete the braking action, L safe Indicates the safe distance from the target, K brake It represents the ratio of deceleration to brake pedal, K represents the low-pass filter coefficient, and t represents the time.

[0061] The beneficial effects of the present invention are that the control method of rear lateral crossing warning based on the electronic rearview mirror of the present invention realizes the RCTA warning function based on the electronic rearview mirror, and does not increase the hardware cost. In addition, the method can dynamically adjust the RCTA warning area for reasonable warning according to the vehicle posture when the vehicle is parked or driving at a low speed, the angle between the rear position and the curb. The timeliness of the RCTA warning is dynamically adjusted according to the steering wheel angle and the speed of the vehicle. When the vehicle is within the collision limit during the reversing process, the electronic rearview mirror triggers a brake signal to control the braking of the entire vehicle to avoid collision. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0063] Figure 1 It is a flow chart of a control method for rear lateral crossing warning based on an electronic rearview mirror of the present invention.

[0064] Figure 2 This is the RCTA warning area when θ=90° in the present invention.

[0065] Figure 3 It is the RCTA warning area when θ<90° of the present invention.

[0066] Figure 4 It is a schematic diagram of an application scenario of the present invention. DETAILED DESCRIPTION

[0067] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0068] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0069] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0070] like Figures 1 to 4 As shown, the control method of rear lateral crossing warning based on electronic rearview mirror of the present invention comprises the following steps: S1, the vehicle is started, and the electronic rearview mirror is powered on to complete initialization. S2, the real-time image behind the vehicle is displayed in the electronic rearview mirror. S3, the electronic rearview mirror obtains the vehicle body signal and analyzes the vehicle gear signal tg, the vehicle speed V1, the vehicle lateral acceleration a 1h , the longitudinal acceleration of the vehicle a 1v , vehicle status status1 and steering wheel angle steer angle S4. The electronic rearview mirror adjusts the field of view according to the vehicle gear signal tg. When the vehicle gear signal tg is the reverse gear, the electronic rearview mirror displays the temporary field of view for reverse driving. S5. Detect whether there is a horizontally passing target in the temporary field of view for reverse driving. If so, calculate the warning time threshold TTC min , and determine the RCTA warning area. S6. When the RCTA warning condition is met, the RCTA warning mark is output to remind the driver. S7. When the brake control signal sending condition is met, the electronic rearview mirror sends a brake control signal to the vehicle, causing the vehicle to slow down and stop.

[0071] It should be noted that the electronic rearview mirror (CMS for short) is an indirect vision device that obtains a specified field of view through a system composed of a camera and a monitor. It includes electronic equipment such as a high-definition camera, a digital visual processing system, a safety system, and a liquid crystal display. It is a new type of rearview mirror that can replace the traditional optical rearview mirror. The field of view of a traditional rearview mirror is limited by the structure and angle of the vehicle body, and the images that the owner can see are often limited. Electronic rearview mirrors are generally designed with a main lens and a wide-angle lens. They present images through a display screen, which can provide a wider field of view, eliminate blind spots, help drivers better understand the surrounding environment, and reduce the occurrence of accidents.

[0072] When the vehicle is started, the electronic rearview mirror is powered on and initialized, and then enters the working state. The camera of the electronic rearview mirror captures the image behind the vehicle and displays it. The controller of the electronic rearview mirror obtains vehicle-related parameters, including: the angle θ between the extension line of the vehicle body and the lateral extension line of the curb, target category, target moving direction, target state, target moving speed V2, target lateral acceleration a 2h , target longitudinal acceleration a 2v , the lateral distance L1 between the target and the rear of the vehicle, and the longitudinal distance L2 between the target and the rear of the vehicle. The angle θ is used to determine whether the vehicle is reversing in a straight line or in a curve. The target categories include 0-pedestrians, 1-pedestrians riding electric bikes or motorcycles, and 2-motor vehicles. The target movement direction includes the target moving in the direction close to the vehicle body and the target moving in the direction away from the vehicle body. The target state includes moving and stationary.

[0073] It should be noted that currently there are vertical parking spaces and inclined parking spaces in parking lots. For vertical parking spaces, the parking space is usually backed out in a straight line; for inclined parking spaces, the parking space is usually backed out in a curve. Therefore, for these two situations, the calculation method of the RCTA warning area is different.

[0074] When the angle θ between the extended line of the vehicle body and the horizontal extended line of the curb is 90°, that is, the current parking space is a vertical parking space, and the extended line of the vehicle body is perpendicular to the horizontal extended line of the curb. At this time, the RCTA warning area is the area surrounded by ABCD and the area surrounded by EFGH. The area surrounded by EFGH is symmetrical with the area surrounded by ABCD along the longitudinal center line of the vehicle body. Figure 2 As shown in the figure, with the curb as the x-axis and the longitudinal centerline of the vehicle body as the y-axis, a two-dimensional coordinate system is established. The coordinates of each point ABCD are as follows: The coordinates of point A are (x A ,y A )=(L mn / 2,0), the coordinates of point B are (x B ,y B )=(L mn / 2+L HFOV ,0), the coordinates of point C are (x C ,yC )=(L mn / 2+L HFOV ,-L), the coordinates of point D are (x D ,y D )=(L mn / 2,-L), L mn represents the width of the vehicle, L represents the maximum distance from the rear of the vehicle that the electronic rearview mirror can cover, and L HFOV Indicates the maximum distance of the FOV that the electronic rearview mirror can cover. The coordinates of each point EFGH are as follows: The coordinates of point E are (x E ,y E )=(-L mn / 2,0), the coordinates of point F are (x F ,y F )=(-L mn / 2,-L), the coordinates of point G are (x G ,y G )=(-(L mn / 2+L HFOV ),-L), the coordinates of point H are (x H ,y H )=(-(L mn / 2+L HFOV ),0).

[0075] When the angle θ between the extension line of the vehicle body and the lateral extension line of the curb is less than 90°, the parking space is a tilted parking space. At this time, the RCTA warning area is the area surrounded by A'B'C'D', the area surrounded by E'F'G'H' and the area surrounded by I'J'B'K'. The area surrounded by E'F'G'H' is symmetrical with the area surrounded by A'B'C'D' along the longitudinal center line of the vehicle body. The area surrounded by I'J'B'K' is the area between the lateral extension line of the curb and the area surrounded by A'B'C'D'. Figure 3 As shown in the figure, a two-dimensional coordinate system is established with the curb as the x-axis and the vertical line passing through the middle of the rear of the vehicle as the y-axis. The coordinates of each point are as follows: The coordinates of point A' are (x A' ,y A' )=(L mn / 2,0), the coordinates of point B' are (x B' ,y B' )=(L mn / 2+L HFOV ·sinθ,-L HFOV ·cosθ), the coordinates of point C' are

[0076] The coordinates of point D' are (x D' ,y D')=(-L·cosθ+L mn / 2,-L·sinθ), the coordinates of point I' are (x I' ,y I' )=(L BSD / sinθ,0), the coordinates of point K' are (x K' ,y K' )=(L BSD ·sinθ,-L BSD ·cosθ), the coordinates of point J' are

[0077] (x J' ,y J' )=((L mn ·Len·sinθ+L mn ·L HPOV ·cosθ+2Len·L HFOV ) / 2(Len·sinθ+L HFOV ·cosθ),0), the coordinates of point E' are (x E' ,y E' )=(L mn / 2-L mn ·sinθ,L mn ·cosθ), the coordinates of point F' are (x F' ,y F' )=(L mn / 2-L mn / sinθ-L·cosθ+L mn ·cotθ·cosθ,-(LL mn ·cotθ)·sinθ), G'

[0078] The coordinates of the point are

[0079] (x G' ,y G' )=(-L mn / sinθ-L HFOV / sinθ+L mn / 2-L·cosθ+L mn ·cotθ·cosθ+L HFOV ·cotθ·cosθ,

[0080] -L·sinθ+L mn ·cosθ+L HFOV ·cosθ)

[0081] The coordinates of point H' are (x H' ,y H' )=(L mn / 2-(L mn +L HFOV)·sinθ,(L mn +L HFOV )·cosθ), where

[0082] Len represents the distance between the installation position of the electronic rearview mirror and the rear of the vehicle. BSD Indicates the maximum lateral warning distance of the vehicle's BSD.

[0083] After determining the RCTA warning area, if a target is identified entering the RCTA warning area, the electronic rearview mirror can determine whether to trigger the RCTA warning.

[0084] Before making an RCTA warning judgment, it is necessary to set the RCTA warning conditions. In this embodiment, the RCTA warning conditions include: the vehicle gear signal tg is the reverse gear, there is a horizontally passing target within the detection range, the target is within the RCTA warning area, and the collision time TTC < TTC min When all the above conditions are met, the electronic rearview mirror outputs the RCTA warning sign to warn the driver, otherwise the RCTA warning is cancelled. min The calculation formula is as follows: The lateral collision time is TTC h =2L1 / (2V1+a 1h 2 +2V2+a 2h 2 ), the longitudinal collision time is TTC v =2L2 / (2V1+a 1v 2 +2V2+a 2v 2 ), warning time threshold TTC min = min(TTC h ,TTC v ). h 、TTC v The smaller value is used as the warning time threshold. It can be understood that the collision time represents the time required for the vehicle body to collide with the target from the current moment. The smaller the collision time, the closer the distance between the vehicle body and the target. Therefore, the warning time threshold should be based on the smaller value.

[0085] When the current situation of reversing meets the RCTA warning conditions, the electronic rearview mirror outputs the RCTA warning sign. The electronic rearview mirror sends the warning indication to the central control display to remind the driver to be careful. In addition, when the brake control signal sending conditions are met, the electronic rearview mirror sends a brake control signal to the engine controller to achieve vehicle deceleration and braking. The brake control signal is determined based on the minimum safe distance and collision time TTC. When the real-time lateral distance < L 1min Or real-time longitudinal distance < L2min Or when TTC is less than 2s (i.e. the condition for sending the brake control signal), the brake control signal is triggered and sent to the vehicle. 1min Indicates the minimum lateral distance, L 2min Indicates the minimum longitudinal distance. When the real-time distance (longitudinal and lateral) of the vehicle during the reversing process is less than the minimum distance, it indicates that the vehicle is about to collide with the target. At this time, the electronic rearview mirror outputs a brake signal to the engine controller to assist the driver in braking and avoid a collision.

[0086] For example, when the angle between the extended line of the vehicle body and the lateral extended line of the curb is θ = 90°, the real-time lateral distance L 1t =L1-(V1·T RCTA +a 1v 2 ·T RCTA / 2)-(V2·T RCTA +a 2v 2 ·T RCTA / 2), real-time longitudinal distance L 2t =L2-a 1h 2 ·T RCTA / 2-a 2h 2 ·T RCTA / 2,T RCTA is the predicted reversing time.

[0087] For example, when the angle θ between the extended line of the vehicle body and the lateral extended line of the curb is less than 90°, the real-time lateral distance is The real-time longitudinal distance is L 2t =L2-K5·V1 2 ·sin(steer angle / k steer )·T RCTA / L3-K6·a 2v 2 ·T RCTA / 2, L3 represents the wheelbase of the vehicle, k steer It indicates the ratio of the steering wheel angle to the front wheel angle. K1, K2, K3, K4, K5 and K6 all indicate correction coefficients (the specific values ​​of the correction coefficients can be set according to the actual application scenarios). RCTA is the predicted reversing time. When θ<90°, the vehicle needs to steer when reversing onto the road. Therefore, in the scenario of reversing on a curve, the distance calculation will introduce parameters related to the steering wheel angle.

[0088] In order to improve the comfort and safety of the driver during the reversing process, the percentage of the brake pedal should not be too large, and frequent braking should be avoided. Therefore, this embodiment uses a low-pass filter to filter the deceleration to improve the burr-free braking signal sent to the vehicle, thereby ensuring the comfort of the driver during the braking process. When the vehicle receives the brake control signal, the deceleration of the vehicle is:

[0089] B pectReq_out (t) = K·B pectReq (t)+(1-K)·B pectReq (t-1), where

[0090] B pectReq (t) = K brake ·a 1target (t),

[0091] a 1target (t) = min[(-V1 2 / (2L 2t -2L safe )-a 1v ),(-V1 / T brake -a 1v )],

[0092] T barke Indicates the time to complete the braking action, L safe Indicates the safe distance from the target, K brake represents the ratio of the deceleration to the brake pedal, K represents the low-pass filter coefficient, and t represents the time. The target types in this embodiment include 0-pedestrians, 1-pedestrians riding electric bikes or motorcycles, and 2-motor vehicles. Since the moving speeds of pedestrians, electric bikes or motorcycles, and motor vehicles are different, L is set. 1min , L 2min 、T RCTA , L safe There are also differences, and more reasonable values ​​can be obtained through parameter calibration (as shown in Table 1).

[0093] Table 1

[0094] Target Type <![CDATA[L 1min (cm)]]> <![CDATA[L 2min (m)]]> <![CDATA[L safe (m)]]> <![CDATA[T RCTA (s)]]> pedestrian 1.2 1.2 0.2 2 Two-wheeler rider 1.5 1.5 0.2 2 vehicle 2.0 2.0 0.2 4

[0095] In summary, the control method of rear lateral crossing warning based on electronic rearview mirror of the present invention realizes RCTA warning function based on electronic rearview mirror, and will not increase hardware cost. Moreover, the method can dynamically adjust RCTA warning area for reasonable warning according to the vehicle posture when the vehicle is parked or driving at low speed, the angle between the rear position and the curb. According to the steering wheel angle and the vehicle speed, the timeliness of RCTA warning is dynamically adjusted. When the vehicle is within the collision limit range during reversing, the electronic rearview mirror triggers the brake signal to control the brake of the whole vehicle to avoid collision.

[0096] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A control method for rear lateral crossing warning based on electronic rearview mirror, It is characterized in that The following steps are involved: S1, the vehicle is started, and the electronic rearview mirror is powered on and initialized; S2, the electronic rearview mirror displays a real-time image of the rear of the vehicle; S3, the electronic rearview mirror obtains the vehicle body signal and analyzes the vehicle gear signal tg and the vehicle speed V 1 , lateral acceleration of the vehicle a 1h , the longitudinal acceleration of the vehicle a 1v 、Vehicle status 1 and steering wheel angle steer angle ; S4, the electronic rearview mirror adjusts the field of view according to the vehicle gear signal tg, and when the vehicle gear signal tg is the reverse gear, the electronic rearview mirror displays the temporary reverse field of view; S5. Detect whether there is a horizontally moving target in the temporary reversing field of view. If so, calculate the warning time threshold TTC min , and determine the RCTA warning area; S6. When the RCTA warning condition is met, an RCTA warning sign is output to remind the driver; S7. When the brake control signal sending condition is met, the electronic rearview mirror sends a brake control signal to the vehicle, causing the vehicle to decelerate and stop.

2. The control method for rear cross-traffic warning based on an electronic rearview mirror as claimed in claim 1, It is characterized in that When detecting whether there is a transversely moving target in the temporary reversing field of view, the parameters obtained include: the angle θ between the extension line of the vehicle body and the transverse extension line of the curb, the target category, the target moving direction, the target state, and the target moving speed V 2 , target lateral acceleration a 2h , target longitudinal acceleration a 2v , lateral distance L between the target and the rear of the vehicle 1 And the longitudinal distance L between the target and the rear of the vehicle 2 .

3. The control method for rear cross-traffic warning based on electronic rearview mirror as claimed in claim 2, It is characterized in that Identify RCTA warning areas, including: When the angle θ between the extended line of the vehicle body and the lateral extended line of the curb is 90°, the RCTA warning area is the area surrounded by ABCD and the area surrounded by EFGH. The area surrounded by EFGH is symmetrical with the area surrounded by ABCD along the longitudinal center line of the vehicle body. The coordinates of point A are (x A ,y A )=(L mn / 2,0), The coordinates of point B are (x B ,y B )=(L mn / 2+L HFOV ,0), The coordinates of point C are (x C ,y C )=(L mn / 2+L HFOV ,-L), The coordinates of point D are (x D ,y D )=(L mn / 2,-L), L mn represents the width of the vehicle, L represents the maximum distance from the rear of the vehicle that the electronic rearview mirror can cover, and L HFOV Indicates the maximum distance of the FOV that the electronic rearview mirror can cover.

4. The control method for rear cross-traffic warning based on electronic rearview mirror as claimed in claim 2, It is characterized in that Identify RCTA warning areas, including: When the angle θ between the extended line of the vehicle body and the lateral extended line of the curb is less than 90°, the RCTA warning area is the area enclosed by A'B'C'D', the area enclosed by E'F'G'H' and the area enclosed by I'J'B'K'. The area enclosed by E'F'G'H' is symmetrical with the area enclosed by A'B'C'D' along the longitudinal center line of the vehicle body. The area enclosed by I'J'B'K' is the area between the lateral extended line of the curb and the area enclosed by A'B'C'D'. The coordinates of point A' are (x A' ,y A' )=(L mn / 2,0), The coordinates of point B' are (x B' ,y B' )=(L mn / 2+L HFOV ·sinθ,-L HFOV ·cosθ), The coordinates of point C' are The coordinates of point D' are (x D' ,y D' )=(-L·cosθ+L mn / 2,-L·sinθ), The coordinates of point I' are (x I' ,y I' )=(L BSD / sinθ,0), The coordinates of point K' are (x K' ,y K' )=(L BSD ·sinθ,-L BSD ·cosθ), The coordinates of point J' are (x J' ,y J' )=((L mn ·Len·sinθ+L mn ·L HPOV ·cosθ+2Len·L HFOV ) / 2(Len·sinθ+L HFOV ·cosθ),0) The coordinates of point E' are (x E' ,y E' )=(L mn / 2-L mn ·sinθ,L mn ·cosθ), The coordinates of point F' are (x F' ,y F' )=(L mn / 2-L mn / sinθ-L·cosθ+L mn ·cotθ·cosθ,-(LL mn ·cotθ)·sinθ), The coordinate of G' point is (x G' ,y G' )=(-L mn / sinθ-L HFOV / sinθ+L mn / 2-L·cosθ+L mn ·cotθ·cosθ+L HFOV ·cotθ·cosθ,-L·sinθ+L mn ·cosθ+L HFOV ·cosθ) The coordinates of point H' are (x H' ,y H' )=(L mn / 2-(L mn +L HFOV )·sinθ,(L mn +L HFOV )·cosθ), Len represents the distance between the installation position of the electronic rearview mirror and the rear of the vehicle. BSD Indicates the maximum lateral warning distance of the vehicle's BSD.

5. The control method for rear cross-traffic warning based on electronic rearview mirror as claimed in claim 2, It is characterized in that Calculate the warning time threshold TTC min ,include: Calculate the lateral collision time as TTC h =2L 1 / (2V 1 +a 1h 2 +2V 2 +a 2h 2 ), Calculate the longitudinal collision time as TTC v =2L 2 / (2V 1 +a 1v 2 +2V 2 +a 2v 2 ), Warning time threshold TTC min = min(TTC h ,TTC v ).

6. The control method for rear cross-traffic warning based on electronic rearview mirror as claimed in claim 1, It is characterized in that The RCTA warning conditions include: the vehicle gear signal tg is the reverse gear, there is a horizontally moving target within the detection range, the target is within the RCTA warning area, and the collision time TTC < TTC min ; When all the above conditions are met, the RCTA warning mark is output.

7. The control method for rear cross-traffic warning based on electronic rearview mirror as claimed in claim 2, It is characterized in that The brake control signal is output according to the minimum safety distance and the collision time TTC. 1min Or real-time longitudinal distance < L 2min Or when TTC is less than 2s, the brake control signal is triggered and sent to the vehicle. 1min Indicates the minimum lateral distance, L 2min Indicates the minimum vertical distance.

8. The control method for rear cross-traffic warning based on electronic rearview mirror as claimed in claim 7, It is characterized in that When the angle between the extended line of the vehicle body and the lateral extended line of the curb is θ = 90°, Real-time lateral distance L 1t =L 1 -(V 1 ·T RCTA +a 1v 2 ·T RCTA / 2)-(V 2 ·T RCTA +a 2v 2 ·T RCTA / 2), Real-time longitudinal distance L 2t =L 2 -a 1h 2 ·T RCTA / 2-a 2h 2 ·T RCTA / 2, T RCTA is the predicted reversing time.

9. The control method for rear cross-traffic warning based on electronic rearview mirror as claimed in claim 7, It is characterized in that When the angle θ between the extended line of the vehicle body and the lateral extended line of the curb is less than 90°, The real-time horizontal distance is The real-time vertical distance is L 2t =L 2 -K 5 ·V 1 2 ·sin(steer angle / k steer )·T RCTA / L 3 -K 6 ·a 2v 2 ·T RCTA / 2, L 3 represents the wheelbase of the vehicle, k steer Indicates the ratio of the steering wheel angle to the front wheel angle, K 1 , K 2 , K 3 , K 4 , K 5 , K 6 Both represent correction coefficients, T RCTA is the predicted reversing time.

10. The control method for rear cross-traffic warning based on an electronic rearview mirror as claimed in claim 8 or 9, It is characterized in that When the vehicle receives the brake control signal, the vehicle's deceleration is: B pectReq_out (t)=K·B pectReq (t)+(1-K)·B pectReq (t-1), Among them, B pectReq (t) = K brake ·a 1target (t), a 1target (t)=min[(-V 1 2 / (2L 2t -2L safe )-a 1v ),(-V 1 / T brake -a 1v )], T barke Indicates the time to complete the braking action, L safe Indicates the safe distance from the target, K brake It represents the ratio of deceleration to brake pedal, K represents the low-pass filter coefficient, and t represents the time.

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