Obstacle detection system based on mathematical model
阅读说明：本技术 基于数学模型的障碍检测系统 (Obstacle detection system based on mathematical model ) 是由 倪丹 张惠强 陈詠芹 蔡志荣 于 2020-04-15 设计创作，主要内容包括：本申请的基于数学模型的障碍检测系统,通过建立合理的测距雷达报警阈值数学模型,将在车体侧部安装的测距雷达的报警阈值设置为与后轮运行轨迹相适应,从而在前轮转向角确定后即实时规划出相应的报警阈值,且该报警阈值边界与后轮轨迹边界线相切,从而使得测距雷达可实现适应车后轮轨迹的精确报警,同时本申请的屏幕是可以实现人机交互的,可以在接收到操作者操作指令后,雷达随着操作者在视频投影模块的屏幕上的滑动指令而相应的进行滑动,以进行快速确定内轮差区域内是否有障碍物,该障碍检测系统同时结合了视频、雷达、车轮轨迹进行检测报警,且根据车轮的运行轨迹,在保证测距雷达报警覆盖区域与车轮运行轨迹相切的基础上,精确的建立了各报警雷达报警阈值的数学模型,实现了雷达的精确报警。(The obstacle detection system based on the mathematical model sets the alarm threshold of the distance measuring radar arranged on the side part of the vehicle body to be adaptive to the running track of the rear wheel by establishing a reasonable distance measuring radar alarm threshold mathematical model, so that the corresponding alarm threshold can be planned in real time after the steering angle of the front wheel is determined, and the boundary of the alarm threshold is tangent to the boundary line of the track of the rear wheel, so that the distance measuring radar can realize accurate alarm adaptive to the track of the rear wheel of the vehicle, meanwhile, the screen can realize man-machine interaction, after receiving an operation instruction of an operator, the radar can correspondingly slide along with the sliding instruction of the operator on the screen of the video projection module so as to quickly determine whether an obstacle exists in an inner wheel difference area, and the obstacle detection system simultaneously combines video, the radar and the track of the wheels for detection and alarm and can detect and alarm according to the running track of the wheels, on the basis of ensuring that the alarm coverage area of the distance measuring radar is tangent to the running track of the wheel, a mathematical model of alarm threshold values of all the alarm radars is accurately established, and accurate alarm of the radars is realized.)
1. An obstacle detection system based on a mathematical model comprises a video projection module (14), an alarm module (20), a radar ranging module (17), a wheel state acquisition module (18) and a camera module (19), wherein the video projection module (14) comprises a touch display screen (15) and a processor (16), the processor (16) is respectively connected with the alarm module (20), the touch display screen (15), the radar ranging module (17), the wheel state acquisition module (18) and the camera module (19), the camera module (19) is used for acquiring images around a vehicle, the radar ranging module (17) is used for measuring the actual distance between the vehicle and an obstacle, the wheel state acquisition module (18) is used for acquiring the steering angle theta of the front wheel of the vehicle, and the processor (16) establishes a mathematical model of the running track of the rear wheel of the vehicle according to the acquired steering angle theta of the front wheel, the rear wheel running track is calculated, the rear wheel running track is added into a vehicle surrounding image obtained by a camera module (19), and finally, the image data added with the rear wheel running track is transmitted to a touch display screen (15) to be displayed, and the rear wheel running track display device is characterized in that: the radar ranging module (17) establishes a radar alarm mathematical model according to the rear wheel running track calculated by the processor (16), when the radar ranging module (17) detects that an obstacle is located in an alarm threshold value of the radar alarm mathematical model, the processor (16) controls the alarm module (20) to alarm, the radar ranging module (17) comprises at least one ranging radar, the ranging radars are installed on two sides of the vehicle body (5), and one of the ranging radars is recorded as a first ranging radar (8);
the mathematical model of the running track of the rear wheels of the vehicle is as follows:
in the above mathematical model, the automobile steering center O is taken as the origin of coordinates; the axis of the rear wheel is an X axis, the axis perpendicular to the X axis is a Y axis, and X isLRIs the abscissa, y, of the rear inner tireLROn the rear inner tire ordinate, L is the wheel base between the front and rear wheels, θ is the front wheel steering angle:
the first ranging radar (8) alarm mathematical model is calculated as follows:
x1＝xLR-s1·sinβ
y1＝yLR+s1·cosβ
s1α is the angle between the line connecting the first range radar and the origin of coordinates and the line connecting the rear tire and the origin of coordinates, x1Is the first range radar abscissa, y1β is the included angle between the line connecting the rear tyre and the origin of the coordinate and the x axis,1Is a first range radar alarm threshold;
the first distance measuring radar alarm mathematical model can pass through the well-established track (x) of the rear wheel of the vehicleLR,yLR) Obtaining the running track (x) of the first range radar in real time1,y1) First range radar alarm threshold1When the obstacle is at the alarm threshold value of the first range radar1When the scanning sector is formed, the alarm module (20) is controlled to alarm.
2. The mathematical model-based obstruction detection system of claim 1, wherein: radar ranging module (19) still includes second range radar (9), then second range radar warning mathematical model is:
x2＝xLR-s2·sinβ
y2＝yLR+s2·cosβ
s2gamma is an angle between a line connecting the second ranging radar and the origin of coordinates and a line connecting the rear tire and the origin of coordinates, and x2Is the abscissa, y, of the second range radar2Is the ordinate of the second range radar,2is a second radar warning threshold.
3. The mathematical model-based obstruction detection system of claim 2, wherein: the first range radar (8) is located at the rear end of the body (5) of the vehicle, and the second range radar (9) is located at the front end of the body (5) of the vehicle.
4. The mathematical model-based obstruction detection system of claim 2, wherein: a third ranging radar (10) capable of sliding along the front end and the rear end of the vehicle body (5) is further arranged between the first ranging radar (8) and the second ranging radar (9).
5. The mathematical model-based obstruction detection system of claim 4, wherein: the third distance radar (10) alarm mathematical model is as follows:
x3＝xLR-s3·sinβ
y3＝yLR+s3·cosβ
s3＝s0+v·t
x3third range radar abscissa, y, for sliding3Third range radar ordinate, s, for sliding3The distance from the third ranging radar to the rear wheel is the included angle between the line connecting the third ranging radar and the origin of coordinates and the line connecting the rear tire and the origin of coordinates, s0The initial distance of the tire after the third distance measuring radar reaches, v is the sliding speed of the third distance measuring radar on the side part of the vehicle body, and t is the vehicle advancing time;3is the third range radar alarm threshold.
Through the established third distance measuring radar alarm mathematical model, the well-established rear wheel track (x) of the vehicle can be obtainedLR,yLR) Obtaining the running track (x) of the third range radar in real time3,y3) And the third ranging radar alarm threshold3When the obstacle is at the alarm threshold value of the third range radar3When the scanning sector is formed, the alarm module (20) is controlled to alarm.
6. The mathematical model-based obstruction detection system of claim 5, wherein: the set value of v is proportional to the vehicle speed and is guaranteed to be greater than the vehicle speed, v is adaptable to the vehicle speed, the value of v is greater when the vehicle speed is high and the value of v is smaller when the vehicle speed is low.
7. The mathematical model-based obstruction detection system of claim 4, wherein: the vehicle body of the vehicle is characterized by further comprising a third ranging radar driving module (21), the third ranging radar driving module (21) is connected with the processor (16), the third ranging radar driving module (21) comprises a guide rail (25) arranged on the vehicle body (5) of the vehicle, a driving source (22) fixed on the vehicle body (5), a radar mounting seat (24) arranged on the guide rail (25) in a sliding mode, a driving tail end (23) connected between the driving source (22) and the radar mounting seat (24), and the driving source (22) drives the driving tail end (23) to move, thereby driving the radar mounting seat (24) to slide on the guide rail (25), the radar mounting seat (24) is used for mounting a third distance measuring radar, when no operator manually touches and slides the touch display screen, the processor (16) controls the driving source (22) to input power which can enable the radar mounting seat (24) to perform uniform motion at a speed v.
8. The mathematical model-based obstruction detection system of claim 7, wherein: the processor (16) also maps a third range radar trajectory (x)3,y3) Projected into the touch display screen (15), and the touch display screen (15) displays the third distance measuring radar position as an operable state besides displaying the vehicle surrounding environment image and the vehicle rear wheel running track obtained by the camera module (19).
9. The mathematical model-based obstruction detection system of claim 8, wherein: the third ranging radar is set to be displayed on the touch display screen (15) in a dot mode, when the vehicle runs, a driver or an operator clicks the dot through a finger or a touch pen to control the third ranging radar to slide at a speed and a distance in a proportion according to the sliding speed and the distance of the finger or the touch pen, and therefore the third ranging radar performs scanning and early warning actions according to gestures.
10. The mathematical model-based obstruction detection system of claim 9, wherein: the touch display screen (15) can collect the hand speed of a driver or a user operating the touch screen to convert the hand speed command into a speed command of a third distance measuring radar action in real time, so that corresponding feedback output can be obtained according to the input of an operator.
Technical Field
The invention relates to the technical field of mathematical modeling, in particular to a fault detection system based on a mathematical model.
Background
When an automobile, particularly a truck or a van with a long wheelbase turns, due to the fact that the wheelbase is long, the difference of the inner wheels exists, a vision blind area exists during turning, and serious traffic accidents are easily caused. In the prior art, many safety systems for the situation appear, for example, patent document 1 discloses an intelligent early warning system and an early warning method for the inner wheel difference based on video projection, in the early warning system, a video and an ultrasonic ranging module are used for synchronous early warning, the obstacle information detected by the ultrasonic ranging module is input into the video module together with the track information of the vehicle for displaying, so that a driver or a user can conveniently check the situation of the side vehicle, the steering safety is ensured, and the ultrasonic warning threshold is adaptively adjusted according to the track line of the wheels of the vehicle, but in the early warning system, the ultrasonic warning threshold is calculated according to the maximum turning angle of a steering wheel, so the threshold cannot adapt to the steering angle of different front wheels of the vehicle to change in real time, and therefore, the distance measuring mode still has the problem of insufficient precision, meanwhile, the calculation of the alarm threshold values K1, K2 and the like has defects, because the ultrasonic ranging is in an arc ranging mode, if the early warning is carried out according to the alarm threshold value, there is still the problem of the alarm range being out of the trajectory so that obstacles that are not within the trajectory will also be detected, causing false alarms, and, at the same time, because the ultrasonic ranging range is equivalent to a circular area, and the track of the rear wheel during turning is also equivalent to a circular area, how to use a plurality of circular areas of the ultrasonic ranging module to fit the circular area edge of the rear wheel track is also a problem to be solved, if the fitting is not in place, the situation of detection failure or missing detection may exist, finally, the video module can only provide a passive display function, lacks an interactive function, and a user can not actively select the position of the ultrasonic wave needing early warning according to the operation of a driver; as another example, reference 2 discloses a trailer turning safety warning system, which uses a millimeter wave radar, a wide-angle camera, a driver mobile terminal, and a pedestrian mobile phone terminal in combination to give an alarm, but the millimeter wave radar in the warning system is fixed, and it is not described how the millimeter wave radar measures obstacles specifically, and the misjudgment probability is high; as shown in reference 3, the present disclosure provides a method, a system, and a vehicle-mounted radar alarm display system, which respectively set radar alarm areas in different areas at the front end and the rear end of a vehicle body, and set alarm thresholds in different sections for different radar alarm areas, and trigger alarms with different alarm tone frequencies when an obstacle is at different distances from a radar, so as to provide a difference prompt effect for obstacles at different distances, thereby improving the accuracy and reliability of vehicle-mounted radar alarm display, but the radar alarm thresholds are set by manufacturers and cannot be set correspondingly to the state of the wheels of a vehicle, and cannot be adapted to the wheel track, and the judgment method is to alarm when the obstacle is not touched, and further increases the driving pressure of a driver for a driver with a vision blind area, and the method cannot be applied to the early warning of the inner wheel difference.
[ patent document 1] CN 108528337A;
[ patent document 2] CN 104477094B;
[ patent document 3] CN 110406489A.
In summary, in the prior art, for obstacle detection of a vehicle, although a mode of combining a video and an ultrasonic ranging module is used to project wheel tracks and obstacle information into the video for a driver to view, the video information can only provide services passively, but cannot interact according to the operation of the driver, and the used ultrasonic ranging modules are all fixedly arranged at the side of the vehicle, and there is no ultrasonic ranging module capable of performing sliding motion relative to the vehicle to adapt to the sliding operation of the driver on the video to perform motion so as to detect whether there is an obstacle at the side of the vehicle in different vehicle areas, and there is no obstacle detection system based on a mathematical model.
The application provides an obstacle detection system is including the ultrasonic ranging module that can remove, this ultrasonic ranging module's that can remove alarm threshold value can adapt to the vehicle orbit, the operator gesture changes, it can remove for the automobile body with certain speed before not obtaining operator gesture removal command, thereby can solve the problem at circular region orbit edge when the circular region simulation rear wheel of ultrasonic ranging module turns, further improve the alarm accuracy, also make the system more intelligent simultaneously.
Disclosure of Invention
In order to overcome the defects of the existing obstacle detection system, the invention provides a technical scheme, the obstacle detection system based on a mathematical model comprises a video projection module, an alarm module, a radar ranging module, a wheel state acquisition module and a camera module, wherein the video projection module comprises a touch display screen and a processor, the processor is respectively connected with the alarm module, the touch display screen, the radar ranging module, the wheel state acquisition module and the camera module, the camera module is used for acquiring images around a vehicle, the radar ranging module is used for measuring the actual distance between the vehicle and an obstacle, the wheel state acquisition module is used for acquiring the steering angle theta of a front wheel of the vehicle, the processor establishes a mathematical model of the track of a rear wheel of the vehicle according to the acquired steering angle theta of the front wheel, calculates the running track of the rear wheel, and adds the running track of the rear wheel into the images around the vehicle acquired by the camera module, and finally, transmitting the image data added with the rear wheel running track to a touch display screen for displaying, wherein the touch display screen is characterized in that: the radar ranging module establishes a radar alarm mathematical model according to the rear wheel running track calculated by the processor, and when the radar ranging module detects that the obstacle is located within an alarm threshold value of the radar alarm mathematical model, the processor controls the alarm module to alarm, the radar ranging module comprises at least one ranging radar, the ranging radars are installed on two sides of the vehicle body, and one of the ranging radars is a first ranging radar;
the mathematical model of the running track of the rear wheels of the vehicle is as follows:
in the above mathematical model, the automobile steering center O is taken as the origin of coordinates; the axis of the rear wheel is an X axis, the axis perpendicular to the X axis is a Y axis, and X isLRIs the abscissa, y, of the rear inner tireLROn the rear inner tire ordinate, L is the wheel base between the front and rear wheels, θ is the front wheel steering angle:
the first ranging radar alarm mathematical model is calculated as follows:
x1＝xLR-s1·sinβ
y1＝yLR+s1·cosβ
s1α is the angle between the line connecting the first range radar and the origin of coordinates and the line connecting the rear tire and the origin of coordinates, x1Is the first range radar abscissa, y1β is the included angle between the line connecting the rear tyre and the origin of the coordinate and the x axis,1Is a first range radar alarm threshold;
the first distance measuring radar alarm mathematical model can pass through the well-established track (x) of the rear wheel of the vehicleLR,yLR) Obtaining the running track (x) of the first range radar in real time1,y1) First range radar alarm threshold1When the obstacle is at the alarm threshold value of the first range radar1When the scanning sector is formed, the alarm module is controlled to give an alarm.
Preferably, radar ranging module still includes second range radar, then second range radar alarm module mathematical model is:
x2＝xLR-s2·sinβ
y2＝yLR+s2·cosβ
s2is the distance from the second distance measuring radar to the rear wheel, and gamma is the second distanceThe included angle between the connecting line of the two distance measuring radars and the origin of coordinates and the connecting line of the rear tire and the origin of coordinates, x2Is the abscissa, y, of the second range radar2Is the ordinate of the second range radar,2is a second radar warning threshold.
Preferably, the first ranging radar is located at a rear end of a body of the vehicle and the second ranging radar is located at a front end of the body of the vehicle.
Preferably, a third ranging radar capable of sliding in the front-rear end direction of the vehicle body is further provided between the first ranging radar and the second ranging radar.
Preferably, the alarm mathematical model of the third range radar is:
x3＝xLR-s3·sinβ
y3＝yLR+s3·cosβ
s3＝s0+v·t
x3third range radar abscissa, y, for sliding3Third range radar ordinate, s, for sliding3The distance from the third ranging radar to the rear wheel is the included angle between the line connecting the third ranging radar and the origin of coordinates and the line connecting the rear tire and the origin of coordinates, s0The initial distance of the tire after the third distance measuring radar reaches, v is the sliding speed of the third distance measuring radar on the side part of the vehicle body, and t is the vehicle advancing time;3for a third range radarAnd (4) an alarm threshold value.
After the third distance measuring radar alarm mathematical model is established, the well-established track (x) of the rear wheel of the vehicle can be usedLR,yLR) Obtaining the running track (x) of the third range radar in real time3,y3) Third range radar alarm threshold3When the obstacle is at the alarm threshold value of the third range radar3When the scanning sector is formed, the alarm module is controlled to give an alarm.
Preferably, v is a set value which is larger than the traveling speed of the vehicle, and v may be adapted to the traveling speed of the vehicle, and becomes larger when the traveling speed of the vehicle is fast and becomes smaller when the traveling speed of the vehicle is slow.
Preferably, still include third range radar drive module, third range radar drive module is connected with the treater, third range radar drive module is including setting up the guide rail on the automobile body of vehicle, be fixed in the driving source on the automobile body, the radar mount pad of slip setting on the guide rail, connect the drive end between driving source and radar mount pad, the action is carried out to driving source drive end, thereby it slides on the guide rail to drive the radar mount pad, the radar mount pad is used for installing third range radar, the radar mount pad is not having the operator to carry out manual touching to touch display screen, during sliding operation, control the power that the driving source input can make the radar mount pad carry out the action at the uniform velocity by the treater.
Preferably, the processor also directs a third range radar trajectory (x)3,y3) And the third distance measuring radar is projected to the touch display screen, and the touch display screen displays the image of the surrounding environment of the vehicle and the running track of the rear wheels of the vehicle, which are obtained by the camera module, and displays the position of the third distance measuring radar in an operable state.
Preferably, the third ranging radar is set as a dot and displayed on the touch display screen, and when the operator drives, the driver or the operator clicks the dot with a finger or a stylus pen to control the third ranging radar to output a corresponding control speed and a corresponding sliding distance for sliding according to the sliding of the finger or the stylus pen, so as to perform scanning and early warning actions.
Preferably, the touch display screen can acquire the hand speed of a driver or a user operating the touch screen to convert the hand speed command into a speed command of the third ranging radar action in real time, so that corresponding feedback output can be obtained according to the input of the operator.
The invention has the beneficial effects that:
1) the obstacle detection system based on the mathematical model projects the motion trail of the rear wheel to the video module in the vehicle by establishing the reasonable mathematical model of the motion trail of the wheel and the ultrasonic ranging module, the alarm threshold value of the ultrasonic ranging module in the obstacle detection system can be calculated according to the wheel trail and the mathematical model of the motion trail of the ultrasonic ranging module, and the alarm threshold value is updated in real time along with the real-time corner data of the front wheel of the vehicle, so that the alarm of the ultrasonic ranging module is further ensured to follow the wheel trail, and the alarm precision is further improved;
2) furthermore, the obstacle detection system based on the mathematical model is based on a vehicle turning mechanism, an ultrasonic distance measurement module is arranged at the position of the side part of the vehicle close to the rear wheel, another ultrasonic distance measurement module is arranged at the position of the side part of the vehicle body close to the head of the vehicle, the alarm threshold values of the two ultrasonic distance measurement modules are respectively adapted to the track of the wheel and the motion track of the ultrasonic distance measurement module, and the obstacle detection system is updated according to real-time corner data of the front wheel of the vehicle, so that the alarm precision is improved;
3) furthermore, the obstacle detection system based on the mathematical model is characterized in that an ultrasonic distance measurement module capable of transversely sliding along a vehicle body is arranged between the two ultrasonic distance measurement modules, the ultrasonic distance measurement module slides relative to the vehicle body in a forward movement direction from the rear part of the vehicle body at a certain speed, and an alarm threshold value can be updated in real time according to a rear wheel running track, so that obstacle information to be collided can be predicted in advance according to corner information of the vehicle, early warning is carried out when collision is possible, and a driver is prompted to carry out corresponding treatment;
4) furthermore, the moving ultrasonic ranging module can compensate for scanning measurement areas omitted by the ultrasonic ranging module arranged at the position, close to the rear wheel, of the side part of the vehicle and the other ultrasonic ranging module arranged at the position, close to the vehicle head, of the side part of the vehicle body, and in the whole moving process, the alarm threshold value of the moving ultrasonic ranging module changes in real time along with the motion track of the wheel;
5) furthermore, the obstacle detection system of the application projects the position of the movable ultrasonic ranging module in the video projection module besides the vehicle track and the obstacle information, an operator can select the ultrasonic ranging module by using fingers or other tools (such as a touch pen), the video projection module calculates a corresponding sliding operation instruction according to the sliding input of the fingers, such as the upward sliding or downward sliding of the operator, converts the instruction into the actual moving amount of the one-way ultrasonic ranging module, so that the operator can check whether the position at a certain position of the vehicle is an obstacle in real time, the alarm threshold value of the movable ultrasonic ranging module is adaptive to the wheel track, and the operator can better master the external environment at the side of the vehicle through the interaction, so that the vehicle can turn more safely, avoiding collision.
Drawings
FIG. 1 is a schematic view of a vehicle turning;
FIG. 2 is a schematic diagram of an obstacle detection system according to the present invention;
FIG. 3 is a schematic diagram of an obstacle detection system of the present invention including two range radars;
FIG. 4 is a schematic diagram of an obstacle detection system of the present invention including three range radars;
FIG. 5 is a schematic diagram of a mathematical model established by the obstacle detection system of the present invention;
FIG. 6 is a schematic diagram of a third driving module of the range radar;
FIG. 7 is a schematic view of a world coordinate system, a camera coordinate system, and an image coordinate system;
fig. 8 is a schematic diagram of the relationship between the image coordinate and the length coordinate.
Description of the reference symbols
1. A vehicle; 2. a rear wheel track; 3. a front wheel track; 4. a headstock; 5. a vehicle body; 6. a turning inside front wheel; 7. a rear wheel on the inner side of the turn; 8. a first range radar; 9. a second range radar; 10. a third range radar; 11. a first range radar track; 12. a second range radar track; 13. a camera; 14. a video projection module; 15. a touch display screen; 16. a processor; 17. a radar ranging module; 18. a wheel state acquisition module; 19. a camera module; 20. an alarm module; 21. a third range radar driving module; 22. a drive source; 23. a drive tip; 24. a radar mount; 25. a guide rail.
Detailed Description
The present invention is further illustrated by the following examples, which are not intended to be limiting in any way, and any modifications or alterations based on the teachings of the present invention are intended to fall within the scope of the present invention.
As shown in fig. 1, which is a steering diagram of a typical automobile designed according to ackermann writing geometry, the centers of the front wheel track 3 and the rear wheel track 2 meet at a steering center O on an extension line of a rear axle of a wheel of the automobile 1, and θ in fig. 1 is a front wheel steering angle, and the front wheel steering angle information can be obtained from an OBD system of the automobile. Since the front wheel track is located inside the rear wheel track when the vehicle 1 is turning, there is an "inner wheel difference" region where the driver's sight is restricted, and therefore an obstacle detection system capable of assisting the driver in traveling is urgently required.
As shown in fig. 2, the obstacle detection system based on a mathematical model of the present application includes a video projection module 14, an alarm module 20, a radar ranging module 17, a wheel state acquisition module 18, and a camera module 19, the video projection module 14 includes a touch display screen 15 and a processor 16, the processor 16 is respectively connected to the alarm module 20, the touch display screen 15, the radar ranging module 17, the wheel state acquisition module 18, and the camera module 19, the camera module 19 is used for acquiring images around the vehicle, the radar ranging module 17 is used for measuring actual distance between the vehicle and an obstacle, the wheel state acquisition module 18 is used for acquiring parameters such as a front wheel steering angle θ and a vehicle speed of the vehicle from an OBD system of the vehicle, the processor 16 establishes a mathematical model of a vehicle rear wheel trajectory from the acquired front wheel steering angle θ, calculates a rear wheel running trajectory, and adds the rear wheel running trajectory to the images around the vehicle acquired by the camera module 19, finally, the image data added with the rear wheel running track is transmitted to a touch display screen 15 to be displayed, meanwhile, a radar ranging module 17 establishes a radar alarm mathematical model according to the rear wheel running track calculated by a processor 16, when the radar ranging module 17 detects that an obstacle is located within an alarm threshold value of the radar alarm mathematical model, the processor 16 controls an alarm module 20 to alarm, the radar ranging module 17 comprises at least one ranging radar, the ranging radars are installed on two sides of the vehicle body 5, and one of the ranging radars is recorded as a first ranging radar 8;
as shown in fig. 3-5, the mathematical model of the vehicle rear wheel trajectory is as follows:
in the above mathematical model, the automobile steering center O is taken as the origin of coordinates; the axis of the rear wheel is an X axis, the axis perpendicular to the X axis is a Y axis, and X isLRIs the abscissa, y, of the rear inner tireLROn the rear inner tire ordinate, L is the wheel base between the front and rear wheels, θ is the front wheel steering angle:
the first ranging radar 8 alarm mathematical model is calculated as follows:
x1＝xLR-s1·sinβ
y1＝yLR+s1·cosβ
s1α is the angle between the line connecting the first range radar and the origin of coordinates and the line connecting the rear tire and the origin of coordinates, x1Is the first range radar abscissa, y1β is the included angle between the line connecting the rear tyre and the origin of the coordinate and the x axis,1Is a first range radar alarm threshold;
after the established first distance measuring radar alarm mathematical model is used, the established vehicle rear wheel track (x) can be usedLR,yLR) Obtaining the running track (x) of the first range radar in real time1,y1) First range radar alarm threshold1When the obstacle is at the alarm threshold value of the first range radar1When the scanning sector is formed, the alarm module 20 is controlled to give an alarm.
Through the established radar alarm mathematical model, the radar alarm threshold value of the radar ranging module 17 on the vehicle is adapted to the track of the rear wheel, so that the first radar alarm threshold value1The formed scanning sector boundary is tangent to the rear wheel trajectory, real-time scanning and alarming are carried out by the first radar alarming module in the process of turning the vehicle, the radar alarming precision is improved, the radar alarming threshold value is made to be adaptive to the rear wheel trajectory, real-time adjustment can be carried out along with the vehicle trajectory, and the universality of the detection system is improved.
Preferably, the radar ranging module 19 further comprises a second ranging radar 9, and the mathematical model of the second ranging radar alarm module is:
x2＝xLR-s2·sinβ
y2＝yLR+s2·cosβ
s2gamma is an angle between a line connecting the second ranging radar and the origin of coordinates and a line connecting the rear tire and the origin of coordinates, and x2Is the abscissa, y, of the second range radar2Is the ordinate of the second range radar,2a second radar alarm threshold;
after the established second distance measuring radar alarm mathematical model is used, the established vehicle rear wheel track (x) can be usedLR,yLR) Obtaining the running track (x) of the second range radar in real time2,y2) Second range radar alarm threshold2When the obstacle is at the alarm threshold value of the second range radar2When the scanning sector is formed, the alarm module 20 is controlled to give an alarm.
Preferably, the first ranging radar 8 is located at the rear end of the vehicle body 5, preferably at the front end edge of the rear wheels, and the second ranging radar 9 is located at the front end of the vehicle body 5, preferably at the front end edge of the vehicle body 5;
through set up a pair of first range radar 8 and a pair of range radar 9 respectively in automobile body 5 both sides, and first range radar 8 is located the rear end of automobile body 5, second range radar 9 is located the front end of automobile body 5, then at the whole in-process that vehicle 1 turned to, the second range radar 9 that is located the front end has scanned the region of predicting the automobile body lateral part and probably having collided promptly, the area that the rear wheel portion automobile body is about to collide has been got rid of to the supplementary second range radar 9 combined action of first range radar 8 that is located the rear end simultaneously to two pairs of four range radars that use automobile body front end and rear end have adapted to the condition that the vehicle turned left or turned right and probably collided promptly.
Preferably, a third ranging radar 10 that can slide in the front-rear end direction of the vehicle body 5 is further provided between the first ranging radar 8 and the second ranging radar 9,
the alarm mathematical model of the third range radar 10 is then:
x3＝xLR-s3·sinβ
y3＝yLR+s3·cosβ
s3＝s0+v·t
x3third range radar abscissa, y, for sliding3Third range radar ordinate, s, for sliding3The distance from the third ranging radar to the rear wheel is the included angle between the line connecting the third ranging radar and the origin of coordinates and the line connecting the rear tire and the origin of coordinates, s0The initial distance of the tire after the third distance measuring radar reaches, v is the sliding speed of the third distance measuring radar on the side part of the vehicle body, and t is the vehicle advancing time;3is the third range radar alarm threshold.
After the third distance measuring radar alarm mathematical model is established, the well-established track (x) of the rear wheel of the vehicle can be usedLR,yLR) Obtaining the running track (x) of the third range radar in real time3,y3) Third range radar alarm threshold3When the obstacle is at the alarm threshold value of the third range radar3When the scanning sector is formed, the alarm module 20 is controlled to give an alarm.
Through setting up above-mentioned setting that can carry out gliding third range radar at certain speed v, can compensate the clearance between first range radar alarm threshold value and the second range radar alarm threshold value, gliding third range radar can be followed and is close to first range radar position department and slide to being close to second range radar position department, its alarm threshold value3The boundary of the formed scanning sector is tangent to the boundary of the rear wheel track 2 all the time, the whole alarm area with the rear wheel track 2 as the boundary can be fitted along the boundary of the rear wheel track 2 after the forward motion is carried out relative to the vehicle body, and the boundary of the alarm area is accurate and the rear wheel track 2 is the boundary, so that the alarm precision of the radar ranging module is further improved.
Preferably, v is a set value which is greater than the traveling speed of the vehicle, so that the third radar 10 can move forward relative to the vehicle body 5, and the speed can be adapted to the traveling speed of the vehicle, and the value becomes larger when the traveling speed of the vehicle is high, and the value becomes smaller when the traveling speed becomes low;
preferably, the first range radar 8 and the second range radar 9 are located on the same horizontal plane a, and the horizontal plane B where the third range radar 10 is located is higher or lower than the horizontal plane a, so as to ensure that the third range radar 10 does not interfere with the first range radar 8 and the second range radar 9 when sliding;
preferably, the obstacle detection system further includes a third ranging radar driving module 21, the third ranging radar driving module 21 is connected to the processor 16, the third ranging radar driving module 21 includes a guide rail 25 disposed on the vehicle body 5, a driving source 22 fixed on the vehicle body 5, a radar mounting seat 24 slidably disposed on the guide rail 25, and a driving end 23 connected between the driving source 22 and the radar mounting seat 24, and the driving source 22 drives the driving end 23 to move, so as to drive the radar mounting seat 24 to slide on the guide rail 25; preferably, the radar mounting seat 24 is used for mounting a third distance measuring radar, the driving source 22 may be a hydraulic cylinder, a rotating motor, or the like, and the driving end may be correspondingly configured as a piston rod, a threaded sleeve rod, or the like; preferably, when no operator touches or slides the touch display screen manually, the processor 16 controls the driving source 22 to input power which can make the radar mounting seat 24 move at a constant speed;
preferably, the guide rail 25 extends from the foremost end of the vehicle body 5 to the rearmost end of the vehicle body 5, so that the third ranging radar 10 can slide on the side of the entire vehicle body 5 to further enlarge the scanning area, and so that it can replace the first ranging radar 8 or/and the second ranging radar 9 in their operation when they fail, improving the safety of use of the apparatus.
Preferably, processor 16 also directs a third range radar trajectory (x)3,y3) The third distance measuring radar is projected to the touch display screen 15, the touch display screen 15 displays an image of the surrounding environment of the vehicle and a running track of a rear wheel of the vehicle, which are obtained by the camera module 19, in an operable state, for example, the third distance measuring radar is displayed on the touch display screen 15 in a dot mode, when an operator drives, the operator needs to check whether an obstacle exists in a blind area in an "inner wheel difference" area or whether the obstacle can be touched, or in order to avoid that an obstacle such as an animal, a ball and the like suddenly enters during turning, after clicking the dot by a driver or an operator with a finger or a stylus, the third distance measuring radar can be controlled to output a corresponding control speed and a corresponding sliding distance to slide according to the sliding of the finger or the stylus, so as to perform scanning and early warning actions, and further improve the safety of the system.
Preferably, the touch display screen 15 may collect the hand speed of the driver or the user operating the touch screen to convert the hand speed command into a speed command of the third distance measuring radar action in real time, so that a corresponding feedback output can be obtained according to the input of the operator.
As shown in fig. 7 to 8, the steps of adding the rear wheel movement track and/or the third ranging radar track to the image of the vehicle periphery acquired by the camera module are as follows:
points O and X in FIG. 7C,YC,ZCThe axes are the origin of coordinates and the coordinate axes of the camera coordinate system, O1Points and X, y axes represent the image coordinate system, points O and XW、YW、ZWThe axis represents a world coordinate system, and the conversion relationship between the world coordinate system and the image coordinate system is as follows:
from fig. 7, the world coordinate system can be converted into a camera coordinate system by rotation and translation, and then converted into an image coordinate system by the mapping relationship between the camera coordinate system and the image coordinate system. A certain coordinate in the space coordinate system is (X)W,YW,ZW) Can be transformed to the corresponding point coordinates (X) in the camera coordinate system by the following formula matrixC,YC,ZC)：
In the above formula, R is a rotation matrix of 3 × 3, which is an orthonormal matrix of units, t is a translation vector of 3 × 1, and 0T＝
(0,0,0)T。
Camera coordinate system coordinate (X)C,YC,ZC) The relationship to the image coordinate system coordinates (x, y) is:
according to the above formula, the transformation relationship between the image coordinate system and the world coordinate system is:
where f is the focal length of the camera, and finally the relationship between the length coordinate and the pixel coordinate in the image is obtained according to fig. 8, if the pixel coordinate of a point in the image is (u, v) and the length coordinate thereof is (x, y), the following can be obtained:
expressed as a matrix
Finally, combining the equations, the conversion relation between the pixel coordinate of a certain point in the image and the world coordinate can be obtained:
after the steering center O of the automobile 1 is set as the origin of coordinates, the trajectory equation in the world coordinate system can be changed into the image trajectory in the touch display screen through the above calculation.
Preferably, the vehicle 1 comprises a vehicle head 4 and a vehicle body 5, the camera module 19 comprises a plurality of cameras 13, preferably, the cameras 13 may be wide-angle infrared night vision cameras; preferably, the number of the cameras 13 is 4, and the cameras are respectively arranged on two sides of the rear end of the vehicle head 4 and two sides of the tail end of the vehicle body 5.
Preferably, the touch display screen 15 may be disposed in the cab, and each module and the processor 16 may be in communication connection in a wireless/wired manner; preferably, the touch display screen 15 may be a vehicle navigation display screen or a vehicle driving recorder; preferably, the alarm module 20 may be an audible and visual alarm.
According to the mathematical modeling, the alarm thresholds of the first range radar, the second range radar and the third range radar are updated in real time along with the steering angle theta of the front wheel, the alarm threshold of the sliding third range radar is changed in real time along with the steering angle theta of the front wheel, the vehicle traveling time and the sliding speed of the third range radar, the obstacle detection system is only provided with three range radars on two sides of the truck body of the truck or the long truck respectively, two range radars are fixedly arranged on the front end and the rear end of the truck body respectively, the alarm thresholds of the two range radars correspond to the rear wheel running track of the vehicle, the alarm threshold of the range radar on the front part of the truck body is set to be adaptive to the rear wheel running track, so that the corresponding alarm threshold can be planned in real time after a steering angle is selected, and the alarm threshold boundary is tangent to the rear wheel track boundary line, the distance measuring radar arranged at the rear part of the vehicle body also enables the alarm threshold value to correspond to the running track of the rear wheel of the vehicle, the threshold value boundary of the alarm radar is tangent to the track boundary line of the rear wheel, so that accurate alarm adaptive to the track of the rear wheel of the vehicle can be realized by using two distance measuring radars, meanwhile, in order to avoid the turning of the vehicle, after the distance measuring radar positioned at the front part finishes scanning, and a barrier enters an inner wheel differential area, a sliding third distance measuring radar is arranged, the third distance measuring radar can automatically move along with the advancing of the vehicle, and can also correspondingly slide along with the sliding command of an operator on the screen of the video projection module after receiving the operating command of the operator, so as to rapidly determine whether the barrier exists in the inner wheel differential area, the barrier detection system based on the mathematical model simultaneously combines the video, the radar and the track of the wheel for, and according to the running track of the wheel, on the basis of ensuring that the alarm coverage area of the distance measuring radar is tangent to the running track of the wheel, a mathematical model of each alarm radar alarm threshold value is accurately established, and accurate alarm of the radar is realized.