JP4110922B2 - Vehicle external recognition device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for detecting a relative position to an object by scanning using an electromagnetic wave such as a laser.
[0002]
[Prior art]
There has been proposed an object detection apparatus that divides a laser irradiation range into a plurality of detection areas and determines the presence of an object from the reception intensity of each detection area (see Patent Document 1). In this apparatus, since the added value of the received intensity in each detection area is compared with the threshold value, the object can be reliably detected regardless of the relative distance to the object.
[0003]
[Patent Document 1]
JP 2000-28718 A (pages 4 to 6)
[0004]
[Problems to be solved by the invention]
However, in the apparatus as described in Patent Document 1 described above, when the reflecting object that reflects the electromagnetic wave from the radar cannot completely reflect the electromagnetic wave as a whole (a part of the object is out of the detection range or the like) If the reflective area for the true size is different), the correct relative lateral position may not be detected. This will be described with reference to FIGS. At time t0, there is a vehicle that cuts forward from the adjacent lane in the vehicle traveling direction, and at time t1, a part of the interrupted vehicle enters the radar viewing angle. At this time, the reflective area is detected, and the center positions of the left end and the right end of the detection reflector group are recognized as the lateral position of the vehicle. Therefore, the interrupting vehicle is located at the position indicated by the solid line in FIG. 11, and the lateral position is recognized by the reflector on the left end side only. Thereafter, the entire vehicle at time t2 enters the viewing angle, for recognizing the horizontal position from the right side and the left side of the reflector in the figure, the case of FIG. 11, so that the lateral position is moved to the right in the figure side. FIG. 12 is a time chart showing the relationship between the lateral position of the interrupting vehicle recognized by the object detection device and the width of the object (vehicle width). As shown in the time chart of the lateral position in FIG. 12, when the vehicle width changes greatly, a step is generated in the relative lateral position of the radar output. Therefore, in the processing using this, for example, the relative speed calculation processing, the direction opposite to the actual direction. The relative speed is calculated as the movement of the vehicle, and the obstacle determination process determines that the vehicle to be noted as an obstacle is a non-obstacle.
[0005]
In view of the above-described problems, the present invention is for a vehicle in which an erroneous lateral relative speed is not calculated even when there is a step at the detection position of an object existing near the left and right ends of the radar viewing angle. An object of the present invention is to provide an external recognition device.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, the position of the left and right reflectors of the preceding vehicle located in front of the own vehicle is detected, and the lateral (vehicle width direction) relative position between the own vehicle and the detected preceding vehicle is output. In the vehicle external environment recognition apparatus, comprising: a scanning type distance measuring unit that performs a relative speed calculating unit that calculates a lateral relative speed between the host vehicle and each preceding vehicle from an output of the scanning type distance measuring unit. The distance measurement status grasping means for grasping the distance measurement status of each preceding vehicle based on the output of the distance measuring means, and the calculation of the lateral relative speed of the relative speed calculation means is changed according to the output of the distance measurement status grasping means And a relative speed calculation changing means, wherein the distance measuring status grasping means detects the side of the same preceding vehicle detected near the left and right ends of the viewing angle in the scanning distance measuring means from the output of the scanning distance measuring means. Change of direction position When the value becomes larger than the first threshold value, information for notifying the change of the processing of the relative speed calculation means is output, and the relative speed calculation changing means has the information for notifying the change from the output of the distance measurement status grasping means. When output, the value used for the calculation of the relative speed in the lateral direction is set in consideration of the movement of the preceding vehicle up to that point, thereby solving the above problem.
[0007]
【The invention's effect】
In the present invention, the detection status of each object detected by scanning is grasped. When the change in the lateral position of the same detected object detected in the vicinity of the left and right ends of the viewing angle in the scanning distance measuring means becomes larger than the first threshold value based on the result of grasping the detection status, the relative speed in the lateral direction is By setting the value used for the calculation in consideration of the movement of the preceding vehicle until immediately before, the lateral relative speed calculation process is temporarily changed. Thus, since the lateral relative speed calculated by changing is not calculated as a movement in the opposite direction to the actual direction, the calculation accuracy of the lateral relative speed can be improved.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, although the embodiment of the outside world recognition device for vehicles in the present invention is described based on an example, the present invention is not limited to an example.
[0009]
(First embodiment)
FIG. 1 is a diagram showing a first embodiment of the present invention. First, the configuration will be described. A scanning type laser radar 1 is provided at the head of the vehicle. The laser radar 1 is connected to a radar processing device 2 that extracts obstacle candidates from the scanned result, and the radar processing device 2 has a two-dimensional origin with the vehicle as the origin for one or more obstacle candidates. (Vehicle distance direction and vehicle width direction) Calculation of coordinate values and calculation of the width (size) of obstacle candidates are performed.
[0010]
In addition, a progressive scan type 3CCD camera 3 is installed to quickly grasp the situation ahead of the vehicle. The imaging result of the 3 CCD camera 3 is connected to the image processing device 4. The image processing device 4 stores the image data near the coordinates of the obstacle candidate captured by the radar processing device 2, and detects the object by image processing when the radar detection object is lost due to the pitching variation of the host vehicle. Is implemented.
[0011]
The output of the radar processing device 2 and the output of the image processing device 4 are connected to the external recognition device 5. A vehicle speed detection device 6 that detects the dependent left and right wheel speeds and a steering angle detection device 7 that detects the front wheel steering angle are connected to the external environment recognition device 5 in order to estimate the state quantity of the host vehicle.
[0012]
From the hardware configuration as described above, calculation processing such as distance measurement status grasping means of the present invention and subsequent processing (relative speed calculation processing and obstacle judgment processing) changing means, etc. are performed, and thereby, high-level external recognition for vehicles. The system is implemented.
[0013]
The outside recognition device 5 accurately determines whether each object detected by the radar processing device is an obstacle for the host vehicle, and the determination result is output to the automatic brake control device 8. A negative pressure brake booster 9 that achieves an arbitrary braking force is connected to the front and rear wheels, and a braking force command voltage from the automatic brake control 8 of the host vehicle is applied to the solenoid valve of the negative pressure brake booster 9. Done.
[0014]
Each of the radar processing device 2 and the automatic brake control device 8 includes a microcomputer and its peripheral components, various actuator drive circuits, and the like, and transmits and receives information to and from each other via a communication circuit.
[0015]
FIG. 2 is a block diagram illustrating a control configuration of the vehicle external environment recognition apparatus according to the first embodiment. First, the configuration will be described. 101 in the figure is a scanning distance measuring means 101 for outputting a relative position with respect to an object, and 102 is for calculating the relative speed between the object and the vehicle based on the distance measurement result of the scanning distance measuring means 101. Relative speed calculation means 103, distance measurement status grasping means 103 for grasping the distance measurement status of the object detected by the scanning distance measuring means 101, 104 calculation of the relative speed calculation means 102 triggered by the output of the distance measurement status grasping means 103 Relative speed calculation changing means for changing processing.
[0016]
FIG. 3 is a flowchart showing the relative speed calculation control in the first embodiment. In this embodiment , the scanning result of the scanning laser radar that grasps the situation in front of the vehicle (change in position and width) grasps the distance measurement status of the detected object, and temporarily calculates the relative speed. This is a case where the lateral relative speed is calculated with higher accuracy by changing the value. This control is performed every 100 [ms].
[0017]
In step 201, the position vector (horizontal direction: Px_z ₀ , vertical direction Py_z ₀ ) of each object detected by the scanning laser radar 1 and the width (size: W_z ₀ ) of the object are read. Note that the subscript z ₀ means the current value, z ₁ means the past value of 1 sampling (100 ms), and z _n means the past value of n sampling.
[0018]
In step 202, if the lateral position of the detected object read in step 201 and its past value satisfy the following expression (1), the process proceeds to step 204. If not, the process proceeds to step 203.
abs (Px_z ₀ − Px_z ₁ )> Th_Px (1)
Here, abs (A) is a function that outputs the absolute value of A (argument). Further, Th_Px is a threshold value related to a change in the detection position in the horizontal direction, and may be determined from the horizontal standard deviation of the radar. Specifically, than the standard deviation of the lateral position of the scanning laser play over da set slightly larger value. Thus, the distance measuring conditions satisfying Formula 1 is any usual state not (lateral displacement of the sudden change), it determines the need to temporarily change the processing to be described later.
[0019]
In step 203, if the width of the detected object read in step 201 and its past value satisfy the following equation (2), the process proceeds to step 204. If not, the process proceeds to step 205.
abs (W_z ₀ − W_z ₁ )> Th_W (2)
Here, Th_W is a threshold relating to a change in width, and may be determined from the size of an object as an obstacle. Specifically, an object in which a step is generated near the left and right ends of the viewing angle of the scanning laser radar has a certain vehicle width. In other words, for light vehicles and above, if Th_W is set to a certain size (at least larger than the width of a motorcycle, etc.), the difference between the case where only one side reflector is detected and the case where both side reflectors are detected is given by Equation 2. ranging status that satisfies is any ordinary state not a (the width of the detected object (size) is suddenly changed), it determines the need to temporarily change the subsequent processing.
[0020]
Note that the abs function is used in step 202 and step 203. This is also the case when the detected object moves not only from outside the radar viewing angle to inside but also from inside to outside <temporary processing change>. This is because it is possible to solve the problem related to the lateral position step.
[0021]
In step 204, if the vertical position and the horizontal position of the detected object read in step 201 satisfy the following expression (3), the process proceeds to step 206. If not, the process proceeds to step 205.
K1 Th_L <atan (Px_z ₀ / Py_z ₀ ) <K1 Th_R (3)
Here, atan (A) is a function that outputs the arctangent value of A, K1 is a positive number less than 1, and Th_L and Th_R represent the left and right end angles in the scanning laser radar viewing angle. It is. For example, with a scanning laser radar with a viewing angle of 12 deg, if the right side of the vehicle's direction of travel is positive, Th_L = -6 [deg], Th_R = +6 [deg] with the front of the vehicle as the center (zero deg) Become.
Therefore, when not satisfy Equation 3, the detected object, it is Ru divided a subtle ranging conditions existing in the vicinity of the left and right ends of the radar viewing angle.
[0022]
In step 205, a relative velocity vector (lateral relative velocity: rVx_z ₀ , vertical relative velocity: rVy_z ₀ ) is calculated from the relative position vector of the detected object obtained in step 201 and its past value (Px, Py) as follows: Calculation is performed using the transfer function represented by 4), and the process proceeds to step 207.
G (Z) = (cZ2−c) / (Z2−aZ + b) (4)
Here, Z is a leading operator, and coefficients a, b, and c are positive numbers, and these are discretized at a sampling period of 100 ms so as to have a desired pseudo-differential characteristic. Thus, the relative speed is actually not only prevented from being calculated as a backward motion, Ru can be performed with high accuracy calculation of the relative velocity closer to the actual motion.
[0023]
In Step 206, the detected object position and its past value obtained in Step 201, and the past value of the lateral relative speed obtained in Step 205 (here, in the case of the initial state in which the relative speed is not obtained in Step 205) The past values are all zero) are changed and set as in the following equation, and the lateral relative speed in the current sampling period is calculated. It should be noted that the vertical relative speed is obtained from equation (4) in step 205 (similar to the conventional case because no step or error occurs even at the end of the viewing angle). temp = Px_z ₁ − Px_z ₂ (5)
Px_z ₁ = Px_z ₀ − temp, Px_z ₂ = Px_z ₁ − temp (6)
rVx_z ₀ = a rVx_z ₁ − b rVx_z ₂ + c Px_z ₀ − c Px_z ₂ (7)
Here, the expression (5) may be another calculation method (for example, temp = 0.1 rVx_z ₁ , where 0.1 means a sampling period) if a value representing a change in position is obtained. In addition, the equation (6) resets the past value in consideration of the movement immediately before the “change” with the position immediately after the “change” as a reference. Further, Expression (7) is obtained by rewriting the transfer function of Expression (4) into a state equation of a discrete time system. At first glance, Px_z ₁ is not used, but is used as Px_z _{2 in the} next sampling period.
[0024]
In step 207, the past values of the detected object position and relative speed are updated and the process ends.
[0025]
In this way, in order to correct the lateral relative speed of the sensing object, even if the radar output changes suddenly when the sensing object is present near the left and right edges of the scanning laser radar viewing angle, the lateral relative speed is highly accurate. Can be calculated, and in the obstacle determination process using this, the accuracy of the determination result is improved. Although a case where a plurality of detected objects appear is not specified, when a plurality of objects are detected, the same processing is performed on each object.
[0026]
( Reference example )
Next, a reference example will be described. Since the basic hardware configuration is the same as that of the first embodiment, only different points will be described . In the first embodiment, the relative velocity calculation processing in the lateral direction is temporarily changed with respect to the horizontal position step near the laser radar viewing angle, thereby calculating the relative velocity with higher accuracy. In the reference example , In this case, not only the relative speed calculation process but also the obstacle determination process using the temporary speed change.
[0027]
4 and 5 are flowcharts showing the relative speed calculation control and the obstacle determination control in the reference example. This embodiment is also performed every 100 ms, and step 301 is the same as step 201 in the first embodiment, and is therefore omitted.
[0028]
Step 302 is the same as step 202, but α is obtained from the following equation (8).
_{α = func1 {abs (Px_z 0} - Px_z 1) - Th_Px} ··· (8)
Here, func1 (A) is a function having the characteristics shown in FIG. 6 and has a range of func1∈ [0, 1].
[0029]
Step 303 is the same as step 203, but β is obtained from the following equation (9).
β = func2 {abs (W_z0−W_z1) −Th_W} (9)
Here, func2 (A) is a function having characteristics as shown in FIG. 7, and takes a range of func2ε [0, 1].
[0030]
Step 304 is the same as step 204 except that γ is obtained from the following equation (10).
γ = func3 [abs {atan (Px_z0 / Py_z0)} − K1 Th_R] (10)
Here, func3 (A) is a function having the characteristics shown in FIG. 8, and has a range of func3∈ [0, 1].
[0031]
In step 305, δ is obtained from the history of the position of the detected object obtained in step 301. The following program is shown as a specific example.
δ1 = initial value zero, δ = initial value zero (set to zero when a new object is detected)
if (α> 0.8) δ1 = 10
if (δ1> 0) δ1 = δ1−1 (Decremented every sampling period)
if (abs (Px_z ₀ ) <abs (Px_z ₁ ) and abs (Px_z ₁ ) <abs (Px_z ₂ ) δ = 1
Here, if (expression) statement is a function that executes a statement when expression is satisfied. That is, the position of the object suddenly changes: After .delta.1 = 10, 1 second: .delta.1> 0 within the lateral position of the detection object that Do If [delta] = 1 and approaching the own vehicle.
[0032]
In step 306, if the sum of the values obtained in steps 302 to 304 satisfies the following equation (11), the process proceeds to step 307. If not, the relative speed is calculated in step 205 in the first embodiment. Proceed to step 308.
α + β + γ> Th_Reset (11)
Th_Reset is a positive threshold value for determining whether or not the relative speed should be reset, and is set to 2.1, for example.
[0033]
Step 307 resets the lateral relative speed as follows. Therefore, the actual A to availability and the relative speed is calculated as a backward motion. (The vertical direction is not reset.)
Px_z ₁ = Px_z ₀ , Px_z ₂ = Px_z ₀ (12)
rVx_z ₀ = 0, rVx_z ₁ = 0, rVx_z ₂ = 0 (13)
[0034]
In step 308, the following equation (14) is implemented.
if (γ> Th_γ) Recog [i] = 0, Judge_Finish_Flag [i] = 1 (14)
Here, Th_γ is a positive number less than 1 for determining whether or not the detected object exists at the left and right ends of the radar viewing angle. Both Recog [i] and Judge_Finish_Flag [i] are initially set to zero when a new object is detected. The former is a variable that ranges from 0 to 1, and approaches 1 as the degree of determination as an obstacle increases. The latter is a flag that is set to 1 when the obstacle determination process is completed. i is the ID number of the detected object (if two preceding vehicles are detected, i = 0 and i = 1). In other words, the detection object present at the end of the radar viewing angle is subjected to processing that is not determined to be an obstacle, so that malfunction of the brake can be reliably prevented. Therefore, in practice it is not name that brake incorrectly with respect to the object is non-obstacles.
[0035]
In step 309, the following equation (15) is executed from the sum of the values obtained in steps 302 to 304 for the object not set as Judge_Finish_Flag [i] = 1 in step 308.
if (δ = 0 and α + β + γ> Th_Hold)
Judge_Finish_Flag [i] = 1 (15)
Here, Th_Hold is a threshold value that determines whether or not to hold the detected object, and has a positive value. That is, in order to hold the obstacle determination, the determination end flag of the corresponding detected object number is set to 1. If δ = 1, the lateral position of the detected object has suddenly changed and is approaching in the direction of the vehicle, and it is desired to permit braking control and warning. Ru it is possible to prevent deterioration of the obstacle verification performance near left and right ends of the corner.
[0036]
In step 310, the following obstacle determination (normal determination process) is performed on the object numbers for which Judge_Finish_Flag [i] = 1 is not set in steps 308 and 309. Here, the normal obstacle determination process shown in FIG. 5 will be described.
[0037]
In step 310-1, the vehicle speed Vsp, the steering angle Str, and the yaw rate dψ / dt of the host vehicle in the current sampling are read.
[0038]
In step 310-2, the future movement trajectory of the host vehicle is predicted as the turning radius of the host vehicle from the following equation using the vehicle speed, the steering angle, and the yaw rate obtained in step 310-1.
R = Vsp / (dψ / dt) (in case of Vsp> 30km / h) (16)
R = (lf + lr) / Str (in case of Vsp ≤ 30km / h)
Here, lf and lr represent the distance from the front wheel to the center of gravity and the distance from the rear wheel to the center of gravity, respectively.
[0039]
In step 310-3, the direction of the relative speed vector that is most likely to come into contact with the host vehicle from the position of the detected object read in step 301 is calculated from equation (17). Are obtained from the equation (18).
direction_C [i] = atan (Px_z0 [i] / Py_z0 [i]) (17)
direction_L [i]
= atan ((Px_z0 [i] + W_z0 [i] / 2 + w / 2) / (Py_z0 [i])) (18)
Here, w represents the width of the host vehicle.
Next, the direction of the relative velocity vector of the obstacle candidate with respect to the own vehicle is calculated by the equation (19), and from this, the possibility that the detected object can be an obstacle for the own vehicle is calculated by the equation (20).
direction [i] = atan (rVx_z0 [i] / rVy_z0 [i]) (19)
Recog_rVxy [i] = (-0.2 / fabs (direction_L [i]-direction_C [i]))
* fabs (direction_C [i]-direction [i]) + 1.0 (20)
Here, Recog_rVxy takes a range from 0.8 to 1 when there is a possibility of contact, and becomes smaller as the possibility is lower.
[0040]
In step 310-4, the possibility of contact between the detected object and the own vehicle is obtained from equation (21) from the future movement locus R of the own vehicle calculated by equation (16).
Recog_Dist [i] = (-0.2 / w / 2) * abs (hypot (Py_z0 [i], (Px_z0 [i]-R))-R) + 1.0 (21)
Here, hypot (p1, p2) is an argument that returns (p1 × p1 + p2 × p2) ^0.5 , and Recog_Dist takes a range from 0.8 to 1 when there is a possibility of contact, and the smaller the probability, the smaller the value. Become.
[0041]
In Step 310-5, the two contact possibilities calculated by Expression (20) and Expression (21) are integrated into one contact possibility.
Recog [i] = func4 (Th_rVy_L, Th_rVy_H, rVy_z ₀ [i], Recog_rVxy [i], Recog_Dist [i]) (22) where Th_rVy_L and Th_rVy_H are appropriate thresholds that determine the weight of the obstacle judgment method . func4 (a1, a2, a3, a4, a5) is a function having the characteristics shown in FIG. 9. When the vertical relative speed is small, the result of equation (21) is emphasized, and the relative speed is large. In some cases, the result of Expression (20) is emphasized.
[0042]
In step 311, the obstacle judgment result obtained in steps 308 to 310: Recog [i] is output to the control side, and the past value of each variable is updated in the same manner as in step 207 in the first embodiment, and the process ends.
[0043]
In this way, when a step occurs in the lateral position of the detected object near the left and right ends of the radar viewing angle, or when it is likely to occur, the relative speed calculation process is temporarily changed. Furthermore, the obstacle determination process is also temporarily changed. As a result, it is possible to calculate the relative speed with high accuracy, and it is possible to improve the accuracy of the obstacle determination result, thereby realizing an excellent external environment recognition device for a vehicle.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a basic configuration in a first embodiment.
FIG. 2 is a block diagram showing a control configuration of the external recognition apparatus in the first embodiment.
FIG. 3 is a flowchart showing relative speed calculation control in the first embodiment.
FIG. 4 is a flowchart showing relative speed calculation control in a reference example .
FIG. 5 is a flowchart showing normal obstacle determination processing control in a reference example .
FIG. 6 is a map showing characteristics of a function fanc1 in a reference example .
FIG. 7 is a map showing characteristics of a function fanc2 in a reference example .
FIG. 8 is a map showing characteristics of a function fanc3 in a reference example .
FIG. 9 is a map showing characteristics of a function fanc4 in a reference example .
FIG. 10 is a schematic diagram showing a distance measurement situation when an interrupting vehicle is detected.
FIG. 11 is a diagram illustrating a relationship between a reflector and a vehicle center when an interrupting vehicle is detected.
FIG. 12 is a diagram illustrating a relationship between a lateral position and a vehicle width when an interrupting vehicle is detected.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Laser radar 2 Radar processing device 3 CCD camera 4 Image processing device 5 External field recognition device 6 Vehicle speed detection device 7 Steering angle detection device 8 Automatic brake control device 9 Negative pressure brake booster

Claims (2)

Scanning type distance measuring means for detecting the position of the left and right reflectors of the preceding vehicle located in front of the host vehicle and outputting the lateral (vehicle width direction) relative position between the host vehicle and the detected preceding vehicle;
A relative speed calculating means for calculating a lateral relative speed between the host vehicle and each preceding vehicle from an output of the scanning distance measuring means;
In the vehicle external environment recognition device comprising:
Distance measurement status grasping means for grasping the distance measurement status of each preceding vehicle based on the output of the scanning type distance measurement means;
A relative speed calculation change means for changing the calculation of the lateral relative speed of the relative speed calculation means according to the output of the distance measurement status grasping means;
Provided,
The distance measuring status grasping means detects a change in a lateral position of the same preceding vehicle detected from the output of the scanning distance measuring means near the left and right ends of the viewing angle in the scanning distance measuring means larger than a first threshold value. Output information that informs the change of the processing of the relative speed calculation means,
When the information indicating the change is output from the output of the distance measurement status grasping means, the relative speed calculation changing means considers the movement of the preceding vehicle up to immediately before the value used for calculating the relative speed in the lateral direction. The external environment recognition apparatus for vehicles characterized by setting as follows. Scanning distance measuring means that detects the position of the left and right reflectors of the preceding vehicle in front of the host vehicle, and outputs the lateral (vehicle width direction) relative position between the host vehicle and the detected preceding vehicle and the width of the preceding vehicle. When,
A relative speed calculating means for calculating a lateral relative speed between the host vehicle and each preceding vehicle from an output of the scanning distance measuring means;
In the vehicle external environment recognition device comprising:
Distance measurement status grasping means for grasping the distance measurement status of each preceding vehicle based on the output of the scanning type distance measurement means;
A relative speed calculation change means for changing the calculation of the lateral relative speed of the relative speed calculation means according to the output of the distance measurement status grasping means;
Provided,
In the distance measuring status grasping means, the change in the width of the same preceding vehicle detected from the output of the scanning distance measuring means near the left and right ends of the viewing angle in the scanning distance measuring means is larger than the second threshold value. Sometimes outputting information notifying the change of the processing of the relative speed calculation means,
When the information indicating the change is output from the output of the distance measurement status grasping means, the relative speed calculation changing means considers the movement of the preceding vehicle up to immediately before the value used for calculating the relative speed in the lateral direction. The external environment recognition apparatus for vehicles characterized by setting as follows.

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