A method for early warning of obstacles in dangerous areas of commercial vehicle turning

Abstract

The present invention discloses a method for warning obstacles in a dangerous area of ​​a commercial vehicle turning, comprising: step 1, establishing a rectangular coordinate system with a line connecting the center points of the front wheel and the rear wheel on one side of the truck as the vertical axis and the rear wheel axle as the horizontal axis, and detecting the speed V of the vehicle when turning right by a sensor; A and the turning angle between the vehicle speed and the longitudinal axis #imgabs0# to determine the inner wheel difference danger zone of the truck; step 2, on the basis of the inner wheel difference danger zone, set a warning area; step 3, and use the rear wheel center point as the coordinate origin and the rear wheel axle as the polar axis to establish a polar coordinate system, and determine the pedestrian position through the camera as (θ, ρ p ); Step 4: Determine the equation of the boundary circle of the warning area in the rectangular coordinate system, assume that the polar axis of the polar coordinate system coincides with the horizontal axis, and transform the equation of the boundary circle of the warning area into the polar coordinate equation of the boundary circle of the warning area; Step 5: Determine the positional relationship between the pedestrian and the warning area. By comparing the dangerous area of ​​the real-time inner wheel difference model of the truck with the position of the pedestrian, the danger of the truck turning can be judged.

Description

Technical Field

[0001] The invention relates to an obstacle early warning method for a commercial vehicle turning dangerous area, belonging to the field of traffic safety. Background Art

[0002] Among traffic fatalities, the highest proportion of accidents occur between large trucks and non-motor vehicles and pedestrians. The reason is that there is a large difference in size between large trucks, non-motor vehicles and pedestrians. When an accident occurs, non-motor vehicle drivers and pedestrians lack safety protection. At present, the research on truck turning mainly analyzes the inner wheel difference model of the truck and uses detectors to detect obstacles in the danger zone. The driver still needs to actively judge whether there is a potential danger. And it does not play a good warning role for pedestrians and non-motor vehicles. In view of the above, the invention content of this application is proposed. Summary of the invention

[0003] The present invention designs and develops an obstacle warning method for a commercial vehicle turning danger zone. By comparing the danger zone shown by the real-time inner wheel difference model of the truck with the position of pedestrians, the danger of the truck turning is judged, thus overcoming the problem of not being able to judge the relative position of pedestrians in the inner wheel difference danger zone in real time.

[0004] The technical solution provided by the present invention is:

[0005] A method for early warning of obstacles in a dangerous area when a commercial vehicle is turning, comprising:

[0006] Step 1: Use the line connecting the center points of the front and rear wheels on one side of the truck as the vertical axis and the rear wheel axis as the horizontal axis to establish a rectangular coordinate system. Use the sensor to detect the speed V when the vehicle turns right. A and the angle between the vehicle speed and the longitudinal axis Determine the dangerous area of ​​the inner wheel difference of the truck and calculate the width b of the dangerous area;

[0007] Step 2: Based on the inner wheel difference danger zone, a warning zone is set, and the width of the warning zone is set to

[0008] Step 3: The camera is fixed at the center point of the rear wheel, and a polar coordinate system is established with the center point of the rear wheel as the coordinate origin and the rear wheel axle as the polar axis. The position of the pedestrian is determined by the camera as (θ, ρ p );

[0009] Among them, θ is the angle of the pedestrian in the polar coordinate system, θ∈[0,2π], ρ p The extreme path for pedestrians;

[0010] Step 4: Determine the equation of the boundary circle of the warning area in a rectangular coordinate system, assume that the polar axis of the polar coordinate system coincides with the horizontal axis, and convert the equation of the boundary circle of the warning area into the polar coordinate equation of the boundary circle of the warning area;

[0011] Step 5: Determine the positional relationship between the pedestrian and the warning area. In a rectangular coordinate system, y=kx is set as a straight line tangent to the boundary circle of the warning area. When the pedestrian is located on the straight line y=kx, the polar angle of the pedestrian at this time is θ0;

[0012] When θ∈[θ0,2π], the pedestrian is in the inner wheel difference danger zone and there is a risk of collision, and the system alarms;

[0013] When θ∈[0,θ0), and

[0014] ρ p When ≥ρ(t)1, there is a risk of collision and the system alarms;

[0015] ρ p When ≤ρ(t)2, there is a risk of collision and the system alarms;

[0016] ρ(t)2<ρ p When <ρ(t)1, there is no risk of collision and pedestrians are safe;

[0017] Where ρ(t)1 is the polar diameter on the safe area circle farthest from the origin when the polar angle is θ; ρ(t)2 is the polar diameter on the safe area circle closest to the origin when the polar angle is θ.

[0018] Preferably, the calculation formula of the width b of the dangerous area is:

[0019]

[0020] The calculation formula of the width b1 of the warning area is:

[0021]

[0022] Where L is the distance between the center points of the front and rear wheels of the truck. is the angle between the vehicle speed and the longitudinal axis.

[0023] Preferably, in a rectangular coordinate system, the equation of the warning area boundary circle is:

[0024]

[0025] Among them, the point (x, y) is the rectangular coordinate of the point on the warning area circle.

[0026] Preferably, the polar coordinate equation of the warning area boundary circle is:

[0027]

[0028] Among them, ρ is the lower polar diameter of the point on the warning area circle in the polar coordinate system.

[0029] Preferably, in step 5, the slope of the straight line when the straight line y=kx is tangent to the warning area boundary circle is:

[0030]

[0031] The corresponding pedestrian polar angle at this time is:

[0032]

[0033] Preferably, the step five further comprises:

[0034] When θ≥θ0, the pedestrian is in the warning area and the system alarms;

[0035] When θ<θ0, calculate the polar radius of the point closest to and farthest from the origin on the safety area circle respectively:

[0036]

[0037]

[0038] Where ρ(t)1 is the polar diameter on the safe area circle farthest from the origin when the polar angle is θ; ρ(t)2 is the polar diameter on the safe area circle closest to the origin when the polar angle is θ.

[0039] The beneficial effects described in the present invention are as follows: the present invention determines the danger of truck turning by comparing the danger zone shown by the real-time inner wheel difference model of the truck with the position of pedestrians, thereby solving the problem in previous studies that the relative position of the inner wheel difference danger zone and pedestrians cannot be determined in real time. The front wheel turning angle is used as the input of the inner wheel difference model, eliminating the lag caused by the steering wheel input, thereby ensuring the real-time and accuracy of the inner wheel difference model. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The figure is a schematic diagram of the structure of the obstacle warning system for the turning danger zone of a commercial vehicle according to the present invention.

[0041] Figure 2 The figure is a schematic diagram of the danger zone of the inner wheel difference when a commercial vehicle turns right according to the present invention. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0043] like Figure 1-2 As shown, the present invention provides an obstacle warning method for a commercial vehicle turning danger zone, which determines the danger of the truck turning by comparing the danger zone shown by the real-time inner wheel difference model of the truck with the position of the pedestrian, thereby overcoming the problem that the relative position of the pedestrian in the inner wheel difference danger zone cannot be determined in real time, and includes:

[0044] Step 1: Use the line connecting the center points of the front and rear wheels on one side of the truck as the vertical axis and the rear wheel axis as the horizontal axis to establish a rectangular coordinate system. Use the sensor to detect the speed V when the vehicle turns right. A and the angle between the vehicle speed and the longitudinal axis Determine the dangerous area of ​​the inner wheel difference of the truck and calculate the width b of the dangerous area;

[0045] Step 2: Based on the inner wheel difference danger zone, a warning zone is set, and the width of the warning zone is set to

[0046] Step 3: The camera is fixed at the center point of the rear wheel, and a polar coordinate system is established with the center point of the rear wheel as the coordinate origin and the rear wheel axle as the polar axis. The position of the pedestrian is determined by the camera as (θ, ρ p );

[0047] Among them, θ is the angle of the pedestrian in the polar coordinate system, θ∈[0,2π], ρ p The extreme path for pedestrians;

[0048] Step 4: Determine the equation of the boundary circle of the warning area in a rectangular coordinate system, assume that the polar axis of the polar coordinate system coincides with the horizontal axis, and convert the equation of the boundary circle of the warning area into the polar coordinate equation of the boundary circle of the warning area;

[0049] Step 5: Determine the positional relationship between the pedestrian and the warning area. In a rectangular coordinate system, y=kx is set as a straight line tangent to the boundary circle of the warning area. When the pedestrian is located on the straight line y=kx, the polar angle of the pedestrian at this time is θ0;

[0050] When θ∈[θ0,2π], the pedestrian is in the inner wheel difference danger zone and there is a risk of collision, and the system alarms;

[0051] When θ∈[0,θ0), and

[0052] ρ p When ≥ρ(t)1, there is a risk of collision and the system alarms;

[0053] ρ p When ≤ρ(t)2, there is a risk of collision and the system alarms;

[0054] ρ(t)2<ρ p When <ρ(t)1, there is no risk of collision and pedestrians are safe;

[0055] Where ρ(t)1 is the polar diameter on the safe area circle farthest from the origin when the polar angle is θ; ρ(t)2 is the polar diameter on the safe area circle closest to the origin when the polar angle is θ.

[0056] In the present invention, as a preferred embodiment, binocular cameras are selected and installed at the front and rear of the train.

[0057] like Figure 1 , 2 As shown in the figure, the binocular camera can collect images of the inner wheel difference danger zone, identify pedestrians and non-motor vehicles in the image, determine their positions through the binocular positioning principle, extract image information, and send the collected information feedback to the control center for data processing; the alarm is installed outside the vehicle, and starts working when it receives the command from the control center, and reminds pedestrians outside the vehicle to pay attention to safety through voice. The core algorithm of the control center takes the front wheel angle of the truck as input, and sends the front wheel angle data collected by the front wheel angle sensor to the control center, and establishes a real-time inner wheel difference model for trucks turning right in the control center to determine the danger zone of the truck when turning right. Based on this area, a critical danger zone is expanded, and the positions of pedestrians and non-motor vehicles can be combined to calculate whether the truck and pedestrian are in danger of collision. When danger is detected, the control center issues a command and the alarm starts working.

[0058] 1. Define the inner wheel difference danger zone

[0059] Define the truck's driving direction as the positive direction, one side of the truck as the right side, and the other side as the left side.

[0060] like Figure 2 As shown, when a pedestrian appears in the inner wheel difference danger zone, the system will alarm. The inner wheel difference formation mechanism is the difference between the turning radius of the front wheel and the rear wheel when the vehicle turns.

[0061] Define point A as the center point of the right front wheel of the truck, point B as the center point of the right rear wheel of the truck, take point B as the origin of the coordinate system, take the rear axle of the truck as the horizontal axis of the coordinate system, and take the center line of the right front wheel and the right rear wheel of the truck as the vertical axis of the coordinate system. Establish the coordinate system as described above. When the vehicle turns, the speed of the right front wheel is V. A , the angle between the velocity direction and the vertical axis is The instantaneous center of the vehicle's speed when turning is point O, and the turning trajectories of the right front wheel and the right rear wheel are the outermost arc and the outer arc respectively. The area surrounded by the two is the danger zone caused by the inner wheel difference. The inner wheel difference danger zone is the arc-shaped ring area surrounded by the outermost arc and the second outer arc, which is:

[0062]

[0063] Where L is the distance between the center points of the front and rear wheels of the truck.

[0064] 2. Define warning areas

[0065] The system also starts to alarm when someone appears in the warning area.

[0066] Assume that at any time t, the right front wheel angle measured by the wheel angle sensor is Since it takes a certain amount of time for the system to detect pedestrians and issue a final warning, which is called hysteresis time, if the system starts working when the pedestrian is in the inner wheel difference area, the truck is still moving during the system working period. Due to the existence of hysteresis time, the driver will not hear the alarm until the pedestrian is very close to the vehicle, resulting in untimely response, which may cause an accident. Therefore, a warning area ( Figure 2 The width of the area enclosed by the outer arc and the innermost arc is half of the inner wheel difference danger zone, which is:

[0067]

[0068] 3. Define pedestrian positions

[0069] Still taking point B where the binocular camera is located as the coordinate origin and establishing a polar coordinate system with the horizontal axis as the polar axis, the pedestrian position can be expressed as (θ, ρ p ), where θ is the angle of the pedestrian in the polar coordinate system, θ∈[0,2π], ρ p is the polar diameter of the pedestrian, that is, the distance between the pedestrian and the binocular camera.

[0070] 4. Define the warning area boundary circle

[0071] The boundary circle of the warning area is Figure 2 The circle where the innermost arc of the middle shaded part is located is a safe state if the pedestrian is within this circle. Otherwise, it is a dangerous state and the system will alarm.

[0072] In the rectangular coordinate system with point B as the origin, the equation of the warning area boundary circle is:

[0073]

[0074] Among them, the point (x, y) is the rectangular coordinate of the point on the warning area circle.

[0075] The equation of this circle is the circle where the innermost arc is located. The inside of this circle is the safe area. Now convert the equation into polar coordinate form to facilitate the discussion of the position relationship between pedestrians and the warning area;

[0076] Assuming that the polar axis of the polar coordinate system coincides with the X-axis, the polar coordinate equation of the boundary circle of the warning area is:

[0077]

[0078] Among them, ρ is the lower polar diameter of the point on the warning area circle in the polar coordinate system.

[0079] 5. Relationship between pedestrians and alarm area

[0080] Discuss the relative position relationship between pedestrians and the alarm area when they are at different polar angles:

[0081] Assume that in a rectangular coordinate system with point B as the origin, the pedestrian is located on the straight line y=kx, and the corresponding polar angle in the polar coordinate system is θ, k=tanθ, that is:

[0082] (1) First, find the slope of the straight line between y=kx and the warning area boundary circle:

[0083]

[0084] The corresponding pedestrian polar angle at this time is:

[0085]

[0086] Its significance lies in that when the polar angle θ ≥ θ0 of the pedestrian in the polar coordinate system, the pedestrian is in the alarm area and the system alarms. Since the binocular camera is located at point B, the range of the polar angle of the pedestrian that the camera can capture is θ ∈ [0, 2π];

[0087] Therefore, when the pedestrian is at the polar angle θ∈[θ0,2π], the pedestrian is in the inner wheel difference danger zone and there is a risk of collision, and the system alarms;

[0088] (2) When the pedestrian is at an extreme angle θ∈[0,θ0], we need to discuss the following cases:

[0089] First, find the intersection of the straight line and the boundary circle of the warning area, combine the equation of the straight line with the equation of the boundary circle, and convert the result into polar coordinates to obtain two solutions:

[0090]

[0091] Where ρ(t)1 is the polar diameter farthest from the origin on the safety area circle when the polar angle is θ; ρ(t)2 is the polar diameter closest to the origin on the safety area circle when the polar angle is θ;

[0092] The pedestrian is between ρ(t)1 and ρ(t)2, that is Figure 2 It is safe when there is a blank area in the middle. In other cases, the system starts to alarm.

[0093] 6. In summary

[0094] When the binocular camera detects that the pedestrian's position is at an extreme angle of θ∈[0,θ0], the pedestrian is in the inner wheel difference danger zone and there is a risk of collision, and the system alarms;

[0095] When the polar angle of the pedestrian detected by the binocular camera is θ∈[0,θ0], let the polar radius of the pedestrian be ρ p ,when:

[0096] ρp When ≥ρ(t)1, there is a risk of collision and the system alarms;

[0097] ρ p When ≤ρ(t)2, there is a risk of collision and the system alarms;

[0098] ρ(t)2<ρ p When <ρ(t)1, there is no risk of collision and pedestrians are safe.

[0099] The present invention determines the danger of truck turning by comparing the danger zone shown by the real-time inner wheel difference model of the truck with the position of pedestrians, thereby solving the problem in previous studies that the relative position of the inner wheel difference danger zone and pedestrians cannot be determined in real time. The front wheel turning angle is used as the input of the inner wheel difference model, eliminating the lag caused by the steering wheel input, thereby ensuring the real-time and accuracy of the inner wheel difference model.

[0100] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for early warning of obstacles in a dangerous area of ​​a commercial vehicle, characterized in that: include: Step 1: Use the line connecting the center points of the front and rear wheels on one side of the truck as the vertical axis and the rear wheel axis as the horizontal axis to establish a rectangular coordinate system. Use the sensor to detect the speed V when the vehicle turns right. A and the angle between the vehicle speed and the longitudinal axis Determine the dangerous area of ​​the inner wheel difference of the truck and calculate the width b of the dangerous area; Step 2: Based on the inner wheel difference danger zone, a warning zone is set, and the width of the warning zone is set to Step 3: The camera is fixed at the center point of the rear wheel, and a polar coordinate system is established with the center point of the rear wheel as the coordinate origin and the rear wheel axle as the polar axis. The position of the pedestrian is determined by the camera as (θ, ρ p ); Among them, θ is the angle of the pedestrian in the polar coordinate system, θ∈[0,2π], ρ p The extreme path for pedestrians; Step 4: Determine the equation of the boundary circle of the warning area in a rectangular coordinate system, assume that the polar axis of the polar coordinate system coincides with the horizontal axis, and convert the equation of the boundary circle of the warning area into the polar coordinate equation of the boundary circle of the warning area; Step 5: Determine the positional relationship between the pedestrian and the warning area. In a rectangular coordinate system, y=kx is a straight line tangent to the boundary circle of the warning area. When the pedestrian is located on the straight line y=kx, θ0 is the polar angle of the pedestrian at this time. When θ∈[θ0,2π], the pedestrian is in the inner wheel difference danger zone and there is a risk of collision, and the system alarms; When θ∈[0,θ0), and ρ p When ≥ρ(t)1, there is a risk of collision and the system alarms; ρ p When ≤ρ(t)2, there is a risk of collision and the system alarms; ρ(t)2<ρ p When <ρ(t)1, there is no risk of collision and pedestrians are safe; Where ρ(t)1 is the polar diameter on the safe area circle farthest from the origin when the polar angle is θ; ρ(t)2 is the polar diameter on the safe area circle closest to the origin when the polar angle is θ.

2. The method for warning obstacles in dangerous areas of commercial vehicle turning according to claim 1, characterized in that: The calculation formula of the width b of the danger zone is: The calculation formula of the width b1 of the warning area is: Where L is the distance between the center points of the front and rear wheels of the truck. is the angle between the vehicle speed and the longitudinal axis.

3. The method for early warning of obstacles in dangerous areas of commercial vehicle turning according to claim 2, characterized in that: In the rectangular coordinate system, the equation of the warning area boundary circle is: Among them, the point (x, y) is the rectangular coordinate of the point on the warning area circle.

4. The method for warning obstacles in dangerous areas of commercial vehicle turning according to claim 3, characterized in that: The polar coordinate equation of the warning area boundary circle is: Among them, ρ is the lower polar diameter of the point on the warning area circle in the polar coordinate system.

5. The method for warning obstacles in dangerous areas of commercial vehicle turning according to claim 4, characterized in that: In the step 5, the slope of the straight line when the straight line y=kx is tangent to the warning area boundary circle is: The corresponding pedestrian polar angle at this time is:

6. The method for warning obstacles in dangerous areas of commercial vehicle turning according to claim 5, characterized in that: The step five also includes: When θ≥θ0, the pedestrian is in the warning area and the system alarms; When θ<θ0, calculate the polar radius of the point closest to and farthest from the origin on the safety area circle respectively: Where ρ(t)1 is the polar diameter on the safe area circle farthest from the origin when the polar angle is θ; ρ(t)2 is the polar diameter on the safe area circle closest to the origin when the polar angle is θ.

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