JP3089864B2 - Preceding vehicle detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preceding vehicle detecting device for detecting information such as an inter-vehicle distance to a preceding vehicle traveling in front of a host vehicle and a traveling speed of the preceding vehicle.

[0002]

2. Description of the Related Art A conventional detector of this type is disclosed, for example, in Japanese Patent Application Laid-Open No. 61-23985. In this method, for example, an electromagnetic wave such as a laser beam is output while being swept in front of a vehicle, a reflected wave of the electromagnetic wave is received from a target object, and a distance to the object is detected from a propagation elapsed time from output to reception. It is. As the propagation elapsed time, a propagation delay time from an output timing to receiving a reception signal exceeding a predetermined reception level for the first time is used. As a result, it is possible to obtain information on the direction and the distance from the host vehicle to the reflector, and to know whether there is a risk of becoming an obstacle. At this time, generally, the vehicle is provided with a reflex reflector at the rear to improve visibility from behind, and since the reflex reflector serves as a reflector to reflect electromagnetic waves, the vehicle is identified from this. You can also. The inter-vehicle distance detected in this manner is used for automatic traveling of the vehicle, a rear-end collision warning, and the like.

[0003] When used in a rear-end collision warning device for preventing a rear-end collision accident in particular, in addition to the inter-vehicle distance to the preceding vehicle, the preceding inter-vehicle distance is calculated to calculate a safe inter-vehicle distance according to the traveling speed of the preceding vehicle and the own vehicle. It is also required to accurately detect the traveling speed of the vehicle. For this reason, regarding the speed of the preceding vehicle, while calculating the amount of change in the current detection distance with respect to the distance to the preceding vehicle during the past sweep,
Further, the amount of change in the angular direction is also calculated, and the relative speed of the preceding vehicle with respect to the own vehicle is calculated based on these.

[0004]

However, in the above-mentioned conventional preceding vehicle detecting device, it is difficult to reliably obtain data of the same preceding vehicle at the time of the past sweep, and the distance change and the angle change are calculated. There is a problem that is difficult. That is, since the vehicle is accompanied by the yaw rate during the traveling and the data is shifted in the angular direction by the yaw rate of the own vehicle, it is necessary to obtain and correct the yaw rate of the own vehicle at the present time. For this purpose, a commonly available yaw rate sensor may be used, but the current yaw rate sensor often delays the signal or includes noise, so that it is not practically practical.

[0005] Even if the data of the same preceding vehicle at the time of the past sweep is grasped and the amount of change in the distance and the amount of change in the angle can be detected, these data are based on the laser radar device of the own vehicle and the coordinate axis in front of the own vehicle. Is a relative change in the vehicle coordinate system. Therefore, in order to replace the data with speed data on a road coordinate system based on a normal road, it is necessary to consider the motion (speed, angular speed) of the vehicle coordinate system, that is, the motion of the own vehicle. Among the movements of the own vehicle, the speed can be accurately obtained using a vehicle speed sensor, but has the above-mentioned problem with respect to the angular speed, that is, the yaw rate. For this reason, there is a problem that the speed detection accuracy of the preceding vehicle is low, an accurate inter-vehicle distance cannot be calculated, and an appropriate warning cannot be issued. Therefore, the present invention has been made in view of the above-mentioned conventional problems,
It is an object of the present invention to provide a preceding vehicle detecting device in which the yaw rate of the own vehicle is accurately determined, and the distance between the vehicle and the preceding vehicle and the accurate traveling speed of the preceding vehicle are determined.

[0006]

SUMMARY OF THE INVENTION For this reason, the present invention has been described with reference to FIG.
As shown in, radar means 1 which radiates while sweeping the electromagnetic wave in the traveling direction of the own vehicle and detects the distance from the own vehicle to the target and the sweep angle based on the propagation delay time of the reflected wave from the target, Storage means 2 for storing the distance and angle data detected by the radar means 1, distance and angle data detected by the radar means 1 and the distance and angle by sweeping a predetermined time before stored in the storage means 2 A yaw rate detecting means for calculating a yaw rate of the host vehicle by detecting an amount of deviation in the angular direction by comparing the data with the data; a distance and an angle detected by the radar means based on the yaw rate from the yaw rate detecting means; Distance to correct data
Angle data correcting means 4, vehicle discriminating means 5 for extracting data representing a vehicle from the distance and angle data corrected by distance / angle data correcting means 4, and information on the target represented by the extracted data Is output.

[0007]

The yaw rate of the subject vehicle is detected by comparing the distance and angle data of the target detected by the radar means with the distance and angle data obtained at the time of sweeping a predetermined time earlier to detect the amount of deviation in the angular direction. Is done. Since the distance and angle data are corrected based on the yaw rate, the accurate speed of the preceding vehicle is detected.

[0008]

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention. First, a laser radar device 21 receives a laser beam that outputs a laser beam, and a laser beam that has been reflected from a target existing in front of the vehicle among the laser beams output from the beam transmitter 23, and Receiver 2 that converts and amplifies and outputs
5, and a distance detection circuit 27 for detecting the distance to the target based on the propagation delay time of the laser light from the output of the laser light from the light transmitter 23 to the reception of the reflected light at the light receiver 25.
Consists of

As shown in FIG. 3, the laser beam output from the light transmitter 23 is rotated by a laser beam sweeping device 31 using a mirror driven by a step motor. As shown by alternate long and short dash lines u1 and u2 with respect to the line X, the vehicle is swept to the left and right of the vehicle within an angle range of θM. This θM has an amplitude of about ± 10 degrees left and right around the front direction of the vehicle, and a frequency of 50H.
Sweep in z. In one sweep, the sweep angle is set to 200 times, and the sweep angle of the laser light sweep device 31 having a resolution of about 0.1 degree in the angular direction is detected by the laser light sweep direction detection device 33, and the storage circuit 34 And a signal processing circuit 35. The laser beam sweep direction detecting device 33 detects the sweep angle from, for example, the number of drive pulses of a step motor for controlling a mirror.

The storage circuit 34 is supplied with the sweep angle from the laser beam sweep direction detecting device 33 and the detected distance data from the distance detecting circuit 27 and stores them. Signal processing circuit 3
5 includes a yaw rate detecting unit 36, a distance / angle data correcting unit 37, and a position / speed calculating unit 38. The yaw rate detecting section 36 is provided for the distance detecting circuit 2 of the laser radar device 21.
The calculation is performed based on the distance supplied from 7 and the sweep angle supplied from the laser beam sweep direction detection device 33, and the sweep angle and the detected distance data at the time of the sweep before a predetermined time supplied from the storage circuit 34. And the yaw rate of the own vehicle.

The distance / angle data correction unit 37 calculates the data of the distance supplied from the distance detection circuit 27 and the sweep angle supplied from the laser beam sweep direction detection device 33 in accordance with the yaw rate obtained by the yaw rate detection unit 36. Is corrected. Then, the position / speed calculation unit 38 calculates the position and speed of the preceding vehicle based on the corrected data. The calculated position and speed of the preceding vehicle are output to the alarm device 41 via the preceding vehicle position / speed output circuit 40, and an alarm for preventing a rear-end collision is issued based on a predetermined reference.

Next, the principle of yaw rate detection in the yaw rate detecting section 36 will be described. The laser radar device 21 of the own vehicle B sweeps left and right around the vehicle center line X within a range of an angle θM, and reflex reflectors Ra and Rb are installed at the tail of the preceding vehicle M. It is assumed that the vehicle B is traveling on a gentle right curve as shown in FIG. Reflectors Wa, Wb on guardrails etc. on the right and left roadside zones of the road
Is installed.

FIG. 4 shows the detection distance of the target detected for each sweep angle in this situation. In FIG. 4, assuming that the position in the previous sweep of a certain target having data represented by point A at the current detection position is point Q, the sweep angle θ and the detection distance L change from point Q to point A. The following are possible reasons for this. (1) Since the host vehicle B has advanced in the forward direction, the distance has become shorter and the angle has changed. (2) Since the host vehicle B has changed direction, that is, has a yaw rate, the angular direction has changed. (3) The angle direction has changed because the host vehicle B has moved in the lateral direction relative to the target.

In the case of the above (1), all the other data, such as arrows Y1 and Y2, are shortened by the distance that the host vehicle B has advanced forward, and the distance is reduced to the K position. The angle of the data of the target existing on the right increases, and the angle of the data of the target existing on the left decreases. This is represented by the fact that the arrows Y1 and Y2 point in opposite directions with respect to θ. Therefore, when the targets are not unevenly distributed and are appropriately distributed on the left and right sides of the host vehicle B, the distance data becomes shorter by the traveling distance when the overall average is taken, and the angle hardly changes. In the case of (2), the component due to the yaw rate of the own vehicle is not only large but also the arrow Y as a whole.
3, the same amount as Y4. Therefore, if the data obtained by correcting the distance change according to the above (1) with respect to the data before the predetermined time τ is averaged and compared with the data detected this time, it is possible to detect the yaw rate of the own vehicle. It becomes possible. In the case of (3), generally, the amount of lateral movement of the vehicle does not occur much, and is very small and can be ignored as compared with the above (1) and (2).

From the above, the yaw rate detection according to the above (2) is as follows. The function of the detection distance L with respect to the current sweep angle θ is L = F (θ), and the function obtained by correcting the detection distance L with respect to the previous sweep angle θ for a predetermined time τ is L ′ = G (θ). However, when the own vehicle speed is V, the distance change Δ
L is represented by ΔL = V × τ, and L ′ is represented by L ′ = L−ΔL. Then, a correlation function H (Δθ) of G shifted from F by Δθ is defined as follows.

(Equation 1)

If Δθm is determined as Δθ that maximizes H (Δθ), this Δθm is the yaw angle of the host vehicle that has changed during the fixed time τ. The value of the yaw rate dφ / dt is obtained from Δθm, and dφ / dt = Δθm / τ. If the angle change Δθ and the distance change ΔL resulting from the yaw rate calculated in this way are corrected with respect to the detection data of the fixed road object, the change due to the movement of the host vehicle can be canceled. As a result, the position of the target can be obtained on the road coordinate system, and the speed of the target can be obtained from the amount of change with respect to the time.

FIG. 5 shows a main flow of the operation in this embodiment. First, in step 101, a distance / angle calculation process of calculating and storing a detection distance for each sweep angle is performed, and based on the stored distance / angle information, step 103 is performed.
, A distance / angle function calculation process for calculating a function for calculating a correlation with the data before a predetermined time τ is performed. In the next step 105, Δθ that maximizes the correlation is detected from the function of the distance and angle by the angle deviation amount detection processing, and in step 107, the yaw rate is calculated using Δθ. Thereafter, in step 109, a data correction process for correcting the distance / angle information is performed, and a speed calculation process of the target is performed. In step 111, the data of the preceding vehicle is identified from the data, and the position / speed output processing of the preceding vehicle is performed.

FIG. 6 shows the details of the angle / distance calculation processing in step 101. The laser sweep has an angle range of -θM to θ.
M (deg), during which 2θM / Kmax
The laser is output every (deg). Thus, Kmax times of output are performed per one sweep. When the number of the laser output in one sweep is represented by a variable k, the maximum value of k is Kmax. Also, the number of times the distance is detected in one sweep is represented by a variable j. First, in steps 121 and 123, the variables k and j for the processing operation are set to 0 in the signal processing circuit 37. Next, at step 125, the traveling vehicle speed of the own vehicle is
9 is read.

In steps 127 and 129, the sweep angle θ is read from the laser beam sweep direction detecting device 33, and in step 131, the detected distance L is detected by the distance detecting circuit 27.
Is read. In the next step 133, the presence or absence of a detected distance is checked. If a distance is detected, the process proceeds to step 135, where the variable j is incremented. In step 137, the sweep angle θj is detected as an array D (j). Data of the distance Lj is stored. That is,
D (j) = (detection angle θj, detection distance Lj).

Thereafter, at step 139, the next sweep angle command value is output. If there is no distance detection in step 131, the process proceeds from step 133 to step 139, and the next sweep angle command value is output. And step 141
, The value of k is checked, and while it is equal to or smaller than Kmax, the process returns to step 127 to repeat the above for the next laser output. If k = Kmax in step 141, it means that the sweeping of all angles has been completed, and the process proceeds to the distance / angle function calculation processing in step 103. Steps 135 to 13
7 constitutes the storage means of the invention.

FIG. 7 shows step 10 in the main flow.
3 shows details of processing after calculation of the distance / angle function. First, in the yaw rate detection unit, as a distance / angle function calculation process, in step 143, a function L = F (θ) of the distance L with respect to the angle θ is calculated from the array data D (j). Next, at step 145, a distance / angle function L ′ = G (θ) of the data before the predetermined time τ is calculated. Here, as described above, L is corrected by the own vehicle speed V, and L ′ = LV × τ is calculated.

Next, as the angle shift amount detection processing, after setting the shift amount Δθ to -Δθ0 in step 147,
In steps 149 to 153, the shift amount Δθ is set to −Δθ0.
From Δθ0 to Δθ0 in steps of δ
(Δθ) is determined. Then, in step 155, the one indicating the maximum value is selected from H (Δθ) from −Δθ0 to Δθ0, and the value of Δθ at that time is set as the angle deviation amount Δθm during the fixed time τ.

Next, as a data correction process, step 15
7, the yaw rate dφ /
The value of dt is calculated. Then, in step 159, the distance / angle data correction unit performs the array data D (j)
Is corrected in the distance direction by the change ΔL = V × τ due to the own vehicle speed V, and in the angle direction by the amount Δθm due to the yaw rate, and the corrected data is stored as S (j). Steps 143 to 157 constitute the yaw rate detecting means of the invention, and step 159 constitutes the distance / angle data correcting means.

Next, in step 109, the position / velocity calculation unit compares the value of S (j) before the predetermined time τ with the value of this time S (j) as described above to obtain the velocity data ΔS
(J) is calculated. Thereafter, as position / speed output processing, in step 161, data of the preceding vehicle is determined from the data S (j). In order to discriminate and extract the data of the preceding vehicle from the detected targets, a vehicle that does not stop on the road coordinate axis may be determined as the vehicle based on, for example, the speed data ΔS (j). Note that even a stopped target existing in front of the own vehicle can be regarded as a preceding vehicle and its data can be extracted.

If the preceding vehicle is extracted here, step 1
From 63, the process proceeds to step 165, where the position and speed of the preceding vehicle are output, and then the process returns to the distance / angle calculation process of step 101. If the preceding vehicle is not extracted, step 163 is directly executed from step 163.
It returns to the distance / angle calculation processing of 01. Step 109, 1
61 constitutes a vehicle discriminating means, and steps 163 and 165 constitute preceding vehicle information outputting means.

In this embodiment, as described above, without using the yaw rate sensor, the temporal change state of the distance and angle data detected by the radar means is viewed as a whole with respect to the sweep range, and the deviation amount in the angular direction is obtained. Since the yaw rate of the own vehicle is detected by detecting the distance and the angle data currently being processed, the traveling speed of the preceding vehicle can be accurately determined while being free from time delay and noise.

In the above embodiment, the laser beam sweeping device 31 uses a mirror driven by a step motor to swing its direction. However, for example, a galvanometer type device may be used. In that case, in the laser beam sweep direction detecting device 33,
A control signal for controlling the galvanometer can be used as a signal corresponding to the sweep angle.

[0028]

As described above, the present invention compares the distance and angle data of the target detected by the radar means with the distance and angle data obtained at the time of sweeping a predetermined time earlier to determine the amount of deviation in the angular direction. The detection detects the yaw rate of the own vehicle and corrects the distance and angle data based on the yaw rate, so that the accurate speed of the preceding vehicle is detected. As a result, an appropriate safety inter-vehicle distance can be calculated, and an effect that a highly accurate warning can be generated using the rear-end collision warning device or the like can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an embodiment.

FIG. 3 is an explanatory diagram illustrating a traveling environment of a vehicle and a laser light sweep angle.

FIG. 4 is a diagram showing an example of target detection data.

FIG. 5 is a main flowchart showing a flow of an operation in the embodiment.

FIG. 6 is a flowchart showing details of an operation flow.

FIG. 7 is a flowchart showing details of an operation flow.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 radar means 2 storage means 3 yaw rate detection means 4 distance / angle data correction means 5 vehicle discrimination means 6 preceding vehicle information output means 21 laser radar device 23 light transmitter 25 light receiver 27 distance detection circuit 31 laser light sweep device 33 laser light Sweep direction detection device 34 Storage circuit 35 Signal processing circuit 36 Yaw rate detection unit 37 Distance / angle data correction unit 38 Position / speed calculation unit 39 Vehicle speed sensor 40 Previous vehicle position / speed output circuit 41 Alarm device B Own vehicle M Previous vehicle Ra, Rb reflex reflector Wa, Wb reflector

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-111785 (JP, A) JP-A-2-246838 (JP, A) JP-A-4-315080 (JP, A) JP-A-61- 145474 (JP, A) JP-A-62-19781 (JP, A) JP-A-59-192912 (JP, A) JP-A-57-34408 (JP, A) JP-A-61-23985 (JP, A) JP-A-4-248489 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S 13/58-13/64 G01S 13/93 G01S 17/93

Claims (3)

(57) [Claims] A radar means for detecting a distance and a sweep angle from the host vehicle to the target based on a propagation delay time of a reflected wave radiated from the target while radiating while sweeping an electromagnetic wave in a traveling direction of the host vehicle; Storage means for storing the distance and angle data detected by the radar means; comparing the distance and angle data detected by the radar means with the distance and angle data by sweeping a predetermined time before stored in the storage means; A yaw rate detecting means for detecting a deviation amount in the angular direction to calculate a yaw rate of the own vehicle; and distance / angle data for correcting distance and angle data detected by the radar means based on the yaw rate from the yaw rate detecting means. Correction means; vehicle discrimination means for extracting data representing a vehicle from the distance and angle data corrected by the distance / angle data correction means; Preceding vehicle detection device, characterized in that it comprises a preceding vehicle information output means for outputting information about the target object represented by the issued data. 2. The yaw rate detection means calculates a correlation between a value obtained by shifting the distance and angle data obtained by the sweep before the predetermined time in the angular direction by a certain angle and a current distance and angle data, and the correlation function value becomes maximum. 2. The preceding vehicle detection device according to claim 1, wherein a yaw rate of the own vehicle is calculated by using a shift angle at which the yaw rate is shifted by the yaw rate. 3. The system according to claim 2, wherein the yaw rate detection means corrects the distance and angle data obtained by the sweep before the predetermined time, which is compared with the distance and angle data detected by the radar means, based on the own vehicle speed. The preceding vehicle detection device according to claim 1 or 2, wherein