JP2001126194A - Method and device for detecting obstacle for vehicle, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge a danger of the collision of an individual obstacle with one's own vehicle. SOLUTION: A radar 1 irradiates electromagnetic wave and detects reflection wave. A processor 3 searches the target to be an obstacle based on the detection result of the reflection wave by the radar, calculates a target position, the relative speed between the target and the one's own vehicle and the collision predicting time of the target with the one's own vehicle, predicts a danger in the collision of the target with the one's own vehicle based on the calculation result and permits a sound output device 6 to issue alarm in the case where a possibility of danger of collision exists.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an obstacle detection technique suitable for use in vehicles such as passenger cars, trucks, and motorcycles, and more particularly to the risk of collision by judging the danger of individual obstacles. The present invention relates to a vehicle obstacle detection method, a vehicle obstacle detection device, and a recording medium that can issue an alarm when there is a vehicle obstacle detection method.

[0002]

2. Description of the Related Art Conventionally, as an obstacle detecting device for a vehicle, a device using an ultrasonic sensor is mainly used. In the case of a passenger car, ordinary ultrasonic sensors are mounted at four corners of the car and detect a target within a distance of about 50 cm.
Also, a plurality of ultrasonic sensors are attached behind the vehicle,
Some obstacle detection devices detect targets within a distance of 1 to 2 m. Many corner sensors operate at a slow speed of about 20 km / h or less. In the case of a back sensor, it normally operates only when the gear has entered reverse.

[0003] Such a conventional obstacle detection device transmits an ultrasonic wave, and when there is a reflected signal within the detection range, it judges that there is an obstacle such as a human, a telephone pole, a guardrail, and the like.
An alarm is issued to the passenger. In particular, in many cases, when an obstacle is detected, an audible sound is sounded, and the position of the detection sensor is displayed on a liquid crystal display device incorporated in the driver's dashboard, thereby alerting the passenger. This obstacle detection device emits an audible sound intermittently when an obstacle is distant, and emits an audible sound continuously when an obstacle is near, thereby giving the occupant a danger level. To inform.

There is also an obstacle detecting device using a television camera or an infrared camera instead of the ultrasonic sensor. This obstacle detection device detects an obstacle by performing image processing on an image captured by a camera. Further, Japanese Patent Application Laid-Open No. 7-229661 discloses an obstacle detection device that detects the distance to an obstacle behind the vehicle and the direction of the obstacle using an infrared radar, and displays the detected information on an in-vehicle display device. Has been proposed.

Further, Japanese Patent Application Laid-Open No. Hei 8-166448 discloses a method in which a distance to an object is obtained and displayed based on a phase difference between a modulated signal of an electromagnetic wave obtained by pulse-modulating or amplitude-modulating a carrier wave and a detection signal of a reflected wave. An object detection device has been proposed. And in Japanese Patent Application Laid-Open No. 9-318740,
An obstacle detection device that detects an obstacle using a radar that transmits and receives laser light has been proposed.

[0006]

However, the conventional obstacle detecting device using an ultrasonic sensor has a problem that the ultrasonic sensor malfunctions with respect to phenomena such as rain, snow, and ice (freezing). there were. For example, when the vehicle is started in the early morning in a cold region, a warning is always issued from the frozen ultrasonic sensor despite the absence of obstacles, and the warning function itself often needs to be stopped. Further, since the ultrasonic sensor has a short detection distance, it can be used only for checking the surroundings when entering the garage or when starting.

Further, the conventional obstacle detecting device using a television camera or an infrared camera has a problem that the detection capability of the camera is reduced due to temperature or weather conditions (for example, backlight). Furthermore, in the conventional obstacle detection devices, all the obstacles around the vehicle are detected using a sensor for the purpose of distance measurement, but the traveling direction and speed of other vehicles or obstacles such as humans are taken into consideration. There was a problem that the degree of danger could not be determined. Some of the vehicles proposed up to now monitor the inter-vehicle distance with a preceding vehicle and perform cruise control of the vehicle by interlocking this inter-vehicle distance monitoring system with an accelerator / brake control system. However, this technique does not judge the danger due to obstacles around the vehicle.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and accurately detects an obstacle by using a sensor which is not affected by weather conditions, judges the danger of each obstacle, and determines a traffic accident. It is an object of the present invention to provide a vehicle obstacle detection method, a vehicle obstacle detection device, and a recording medium that can realize prevention of occupation and improvement of occupant safety.

[0009]

SUMMARY OF THE INVENTION An obstacle detecting method for a vehicle according to the present invention detects a reflected wave of an electromagnetic wave radiated from a small-sized radar which can be mounted on a vehicle, and detects an obstacle based on the detection result of the reflected wave. A first procedure for detecting a target to be obtained (steps 101 to 103), and a second procedure for calculating a position of the target, a relative speed between the target and the own vehicle, and a predicted collision time between the target and the own vehicle (steps). 104, 105),
A third procedure of predicting a risk of collision between the target and the host vehicle based on the position, relative speed, and predicted collision time of the target, and issuing an alarm when there is a risk of collision (step 1)
06,107). In order to prevent serious accidents, the surrounding monitoring function during traveling is very effective. For example, blind spot monitoring at the time of passing or detection of entanglement at the time of left turn. When the vehicle is running, vehicles are running around the same lane, adjacent lanes, and opposite lanes at the same time. In addition, there are guardrails and signs at the border with the sidewalk. In addition, there are pedestrians and motorcycles on sidewalks and crosswalks. Conventional sensors simply detect the presence of a target. There is no danger judgment function there. For example, vehicles that run in adjacent lanes have a low risk even if the distance between them is 1 m. Conversely, for example, 5m
It is considered that a two-wheeled vehicle that travels straight to the own vehicle from a distance of is high in danger. Judgment of such danger in real time,
It is thought that a device that can generate an alarm will greatly contribute to improving safety. Therefore, according to the present invention, a reflected wave of an electromagnetic wave radiated from a small radar that can be mounted on a vehicle is detected, and based on the detection result of the reflected wave, several tens of meters around the vehicle.
Detect a target that can be an obstacle that exists to a certain degree, calculate the position of the target, the relative speed between the target and the host vehicle, and the estimated collision time between the target and the host vehicle, and determine the risk of collision between the target and the host vehicle. Predict and warn if there is a risk of collision.
Thus, safety can be improved as an occupant assisting device. Further, as one configuration example of the vehicle obstacle detection method of the present invention, in the first procedure, for each sample value obtained by sampling the detection result of the reflected wave, a threshold value is calculated from sample values before and after the sample value. , The goal is to extract a sample value that exceeds this threshold as a goal,
The second procedure determines the cross-correlation between the tracked target detected in the previous radar scan and the newly detected target, associates the tracked target with the newly detected target, and Determining the motion state of the target, and calculating the target position, relative speed, and estimated collision time;
Is a procedure for determining whether or not there is a risk of collision between the target and the host vehicle by comparing the target position, the relative speed, and the predicted collision time with preset values.

[0010] Further, the vehicle obstacle detecting device of the present invention comprises:
A small-sized radar (1) that can be mounted on a vehicle and emits electromagnetic waves to detect reflected waves, alarm output means (5, 6) for notifying that there is a risk of collision with an obstacle, and the radar A target that can be an obstacle is detected based on the detection result of the reflected wave, and the position of the target, the relative speed between the target and the host vehicle, and the collision prediction time between the target and the host vehicle are calculated, and based on the calculation result, Processing means (3) for predicting the danger of a collision between the target and the host vehicle and, if there is a danger of a collision, outputting an alarm to the alarm output means. In addition, the vehicle obstacle detecting device according to the present invention includes:
As a configuration example, the processing unit calculates a threshold value from sample values before and after each sample value obtained by sampling the detection result of the reflected wave, and detects a sample value exceeding the threshold value as a target, Determine the cross-correlation between the tracked target detected in the previous radar scan and the newly detected target, associate the tracked target with the newly detected target, and determine the motion state of each target. Calculating the target position, relative speed, and estimated collision time, and comparing the calculated result with a preset value to determine whether there is a risk of collision between the target and the host vehicle. It is.

[0011] A recording medium on which the vehicle obstacle detection program of the present invention is recorded detects a reflected wave of an electromagnetic wave radiated from a small radar that can be mounted on the vehicle, and detects an obstacle based on the detection result of the reflected wave. The first to detect potential targets
(Steps 101 to 103) and a second procedure (step 10) for calculating the position of the target, the relative speed between the target and the host vehicle, and the estimated collision time between the target and the host vehicle.
A third procedure of predicting a danger of collision between the target and the host vehicle based on the position, relative speed, and predicted collision time of the target, and issuing an alarm if there is a danger of collision; (Steps 106 and 107) are executed by a computer. Then, as one configuration example of a recording medium on which the vehicle obstacle detection program of the present invention is recorded, the first procedure is based on the sample values before and after each sample value obtained by sampling the detection result of the reflected wave. This is a procedure for calculating a threshold value and extracting a sample value exceeding this threshold value as a target. In the second procedure, the target between the tracked target detected in the previous radar scan and the newly detected target is identified. It is a procedure of determining the correlation, associating the target being tracked with the newly detected target, determining the motion state of each target, and calculating the position of the target, the relative velocity and the collision prediction time, The third procedure includes:
This is a procedure for determining whether there is a risk of collision between the target and the host vehicle by comparing the target position, the relative speed, and the collision prediction time with preset values.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] Next, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram illustrating a configuration of a vehicle obstacle detection device according to a first embodiment of the present invention, and FIG. 2 is a flowchart illustrating an operation of the vehicle obstacle detection device of FIG. . The obstacle detecting device for a vehicle shown in FIG. 1 emits an electromagnetic wave and detects a reflected wave.
An A / D converter 2 for converting an envelope signal Env, which is a result of detection of a reflected wave by the radar 1, into digital data; and detecting a target that can be an obstacle based on the digitized envelope signal Env. A processing device 3 for calculating a target position, a relative speed between the target and the host vehicle, and a collision prediction time between the target and the host vehicle, and predicting a risk of collision between the target and the host vehicle based on the calculation result; A memory 4 for storing information on a target being tracked detected by radar scanning and information on a newly detected target, a display device 5 for displaying a detection result, and an alarm sound for notifying a vehicle occupant of danger or And an audio output device 6 for outputting an alarm message.

As shown in FIG. 3, the radar 1 is a pulse radar which continuously emits electromagnetic waves separated in a pulse shape, and detects a reflected wave from an object to measure a distance to the object. It is a sensor. The distance to the object can be measured by the elapsed time from the emission of the radio wave to the reception.

The carrier frequency of the transmission radio wave is, for example, 24 GH
z, and the pulse repetition frequency is, for example, 2 MHz. By using the radar 1 that emits electromagnetic waves in this way, accurate target detection that is not affected by weather conditions can be performed, and the probability of malfunction can be reduced as compared with an ultrasonic sensor. Further, it is possible to detect a long distance due to the nature of the electromagnetic wave, and it is possible to detect a relatively distant target from an early stage.

Further, in the present embodiment, only the transmitting and receiving circuit handles high frequencies, and the other circuits handle low frequencies obtained by converting (down-converting) high frequencies, so that the number of high frequency components is reduced. Therefore, the price of the radar 1 can be reduced. Also, radar 1
Since most of them can be constituted by electric components, they can be miniaturized and can be mounted on a vehicle.

The vehicle on which the vehicle obstacle detection device shown in FIG. 1 is mounted may be a passenger car, a truck, a motorcycle, or the like. To detect obstacles around the vehicle,
It is necessary to mount one or more radars 1 on the vehicle. For example, to detect a forward obstacle, the radar 1 is mounted in the front bumper, and to detect a rear obstacle, the radar 1 is mounted in the rear bumper to detect a lateral obstacle. Mounts the radar 1 in the door mirror. Further, for monitoring the side of a large vehicle, a plurality of radars 1 may be mounted on the lower side of the body.

When a large number of radars operate simultaneously on a public road, radio wave interference may occur. Therefore,
In the present embodiment, a time t from the operation start time of the vehicle obstacle detection device to the transmission pulse generation start time (FIG. 3)
Is converted into a random number so that the time t changes each time the device starts up. Thereby, occurrence of radio wave interference can be suppressed.

The radar 1 as described above outputs an envelope signal Env indicating the intensity of the reflected wave,
The trigger signal Trig is output for each scanning period. Thereafter, after the trigger signal Trig is input, the next trigger signal Tr
One scanning period until an ig is input is called a sweep.

Each time the trigger signal Trig is input, the A / D converter 2 converts the envelope signal Env from analog to digital, and outputs the converted digital data to the processing device 3 (step 101 in FIG. 2). . The processing device 3 has an A /
The digital data input from the D converter 2 is stored in the memory 4
Once (step 102). Trigger signal T
The rig is output, for example, ten times per second, and assuming that the sampling rate of the A / D converter 2 is, for example, 4 kHz, the A / D converter 2 performs 400 samplings for one trigger signal input.

Next, based on the digital data of the envelope signal stored in the memory 4, the processing device 3 performs a target detection process for detecting a target that can be an obstacle of the own vehicle (step 103). FIG. 4 is a flowchart for explaining the target detection processing, and FIGS. 5 and 6 are signal waveform diagrams for explaining the target detection processing. Although the signals handled by the processing device 3 are digital data, for simplicity of description, FIGS. 5 and 6 show each signal in an analog waveform.

In FIG. 5 and FIG. 6, the horizontal axis is time, which corresponds to the distance to the object reflecting the electromagnetic wave, and within one sweep, the further to the right, the longer the distance to the object. Become. In the present embodiment, the trigger signal Tri
The input time of g indicates 0 m, and the time at the end of one sweep indicates 20 m.

FIG. 5 is obtained by each sweep of the radar 1.
The envelope signal Env as shown in (b) indicates that the intensity of the transmitted wave and the reflected wave is inversely proportional to the square of the distance, that the signal is amplified at the output of the radar 1, and that clutter such as ground reflection is present. , The baseline is not always constant.

In order to extract a target that can be an obstacle, a threshold value is set for each sampled value obtained by sampling and digitizing the envelope signal Env, and a signal exceeding this threshold value is extracted as a target. Action is required. However, since the baseline of the envelope signal Env is not constant, the threshold value is not a constant value, but needs to be a dynamic threshold value based on a sample value near the sample value for which the threshold value is set. There is.

FIG. 6 shows how to determine such a threshold value TH1. For example, when determining the threshold value TH1 for the sample value S1 shown in FIG. 6, the processing device 3 calculates an average value μ and a standard deviation σ from a plurality of sample values before and after the sample value S1, and calculates these values. The threshold value TH1 is calculated based on the value. More precisely, the sample value S1 is calculated from an area of the first predetermined length L1 centered on the sample value S1.
, A mean value μ and a standard deviation σ are calculated from a plurality of sample values in a region excluding a region of a second predetermined length L2 (L1> L2), and a threshold value TH1 is calculated based on these values. It is calculated as in the formula.

TH1 = μ + γ × σ (1) In equation (1), γ is a constant (eg, γ = 2).
After calculating the threshold value TH1 for the sample value to be processed among the sample values in one sweep as described above (Step 201 in FIG. 4), the processing device 3 determines that the magnitude of the sample value to be processed is equal to the threshold value TH1. Is determined (step 202).

When the size of the sample value to be processed exceeds the threshold value TH1, the processing device 3 recognizes this sample value as a candidate that can be a target, and sets the size of the sample value to a predetermined threshold value. It is determined whether or not TH2 is exceeded (step 203). The threshold value TH2 is calculated as shown in FIG.
As shown in (b), it is set to increase stepwise according to the time within one sweep (the distance to the object). The reason for setting the threshold value TH2 in this manner will be described below.

As described above, since the intensity of the transmitted wave and the reflected wave is inversely proportional to the square of the distance, the gain of the amplifier (not shown) provided at the output unit of the radar 1 increases the distance to the object. It is set to increase as the distance increases. Accordingly, it is ideal that the baseline of the envelope signal Env is constant, but actually, due to the gain,
The base line tends to increase as the distance to the object increases, which causes a target to be erroneously detected. Therefore, in the present embodiment, more accurate target detection is realized by setting the threshold value TH2 as shown in FIG.

When the size of the sample value to be processed exceeds the threshold value TH2, the processing device 3 recognizes this sample value as a target that can be an obstacle (step 204). Is completed, step 20 is performed for all sample values in one sweep.
It is determined whether or not the processing of steps 1 to 204 has been completed (step 205). If the processing has not been completed, the same processing is performed with the next sample value as the processing target (step 206).

When the processing of steps 201 to 204 is completed for all sample values in one sweep, the processing device 3
Checks the time during which a plurality of sample values extracted as a target continue, and determines whether or not the continuous time RL exceeds a predetermined time LE (step 207). The predetermined time LE functions as a filter for discarding short-time reflections (wrong targets).

When there are a plurality of sample values whose continuous time RL exceeds the predetermined time LE, the processing device 3 sets these sample values as the finally detected target (step 208). Hereinafter, the detected target is referred to as a plot P. The information of the plot P includes a position (distance from the own vehicle) DP. This position DP corresponds to the plot P
The time at which the size of becomes maximum (the reflection intensity becomes maximum) is converted into a distance. Information on the plot P is stored in the memory 4. Thus, the target detection processing ends.

Next, the processing unit 3 determines the motion state of each target based on the information on the track T which is the tracked target detected in the previous sweep and the information on the plot P detected in the target detection processing. Perform target tracking processing to be determined (step 1
04). FIG. 7 is a flowchart for explaining the target tracking processing.

Each track Tn is assigned a track number n in ascending order from 1 each time a track is generated, and further assigned a reliability value TQn (TQn is an integer of 0 or more) indicating the reliability of the track Tn. The reliability value TQn can take a value from 0 indicating the lowest reliability to 7 indicating the highest reliability. Other information of the track Tn includes a predicted position (distance from the own vehicle) DTn of the track Tn and a predicted speed VTn. These information are all stored in the memory 4
Is stored in

First, the processing device 3 performs a correlation determining process for checking a cross-correlation between the track Tn and the plot P (step 301 in FIG. 7). In the correlation determination processing, determination processing is performed on all plots P in order from the plot P at a short distance. For each track Tn, a correlation gate of a predetermined length centering on the track Tn is set for identification and tracking of a target and separation from other targets. The size of the correlation gate is set so that the tracking performance of the target and the separating performance from other targets are compatible.

That is, the correlation gate is set in accordance with the reliability value TQn of the track Tn so as to decrease when the reliability of the track Tn is high and to increase when the reliability of the track Tn is low. In this embodiment, when the reliability value TQn is 4 or more, the reliability is determined to be high, the predetermined length of the correlation gate at this time is SM, and when the reliability value TQn is less than 4, the reliability is low. The predetermined length of the correlation gate at this time is LA (SM <LA).

The position of the plot P to be processed is the track T
n within the correlation gate, plot P and track T
It is assumed that there is a correlation between n. At this time, a correlation may occur between the plurality of plots P and the plurality of tracks Tn. In such a case, the tracks Tn and the plots P are associated one-to-one according to the following indexes.

(A) When one plot P has a correlation with a plurality of tracks Tn, the track Tn closest to this plot P is selected and associated with the plot P. The track Tn associated with the plot P is excluded from the subsequent correlation determination. (B) When a plurality of plots P have a correlation with one track Tn, the plot P closest to the track Tn is selected and associated with the track Tn. The track Tn associated with the plot P is excluded from the subsequent correlation determination. (C) A plot P having no correlated track Tn is a new track.

FIG. 8 is a signal waveform diagram for explaining a specific example of the correlation judgment processing. In the example of FIG. 8, the reliability of the track T1 is high, and the reliability of the tracks T2 and T3 is low. Therefore, the size of the correlation gate set on the track T1 is SM, and the size of the correlation gate set on the tracks T2 and T3 is LA.

Although the plot P1 has a correlation with both the tracks T1 and T2, the track T1 closer to the plot P1 is selected. Now plot P1 and track T
1, and the track T1 is excluded from the correlation determination. The plot P2 also has a correlation with both the tracks T1 and T2, but the track T1 is not subject to the correlation determination. As a result, the track T2 is selected. with this,
The plot P2 and the track T2 are associated with each other, and the track T2 is excluded from the correlation determination.

Since there is no correlated track in the plot P3, it becomes a new track. And
Since the plot P4 has a correlation with the track T3, it is associated with the track T3. As described above, the correlation determination processing ends.

Next, the processing unit 3 smoothes the position and speed of each track Tn in order to predict the position (distance) and speed of each track Tn at the next sweep. First, the processing device 3 calculates the smoothed position DSn (t) of the track Tn in the current sweep as in the following equation (step 302).

DSn (t) = DTn (t) + α × {DPn (t) −DTn (t)} (2) In equation (2), DTn (t) is a track calculated at the time of the previous sweep. The predicted position of Tn, DPn (t) is the position of plot Pn associated with this track Tn,
α is a position smoothing constant described later. The processing device 3 performs such calculation for each track Tn.

Subsequently, the processing device 3 calculates the smoothing speed VSn (t) of the track Tn in the current sweep as in the following equation (step 303). VSn (t) = VTn (t) + β × {DPn (t) −DTn (t)} / Δt (3)

In the equation (3), VTn (t) is the predicted speed of the track Tn calculated at the time of the previous sweep, Δt
Is a time (cycle) of one sweep, and β is a speed smoothing constant described later. The processing device 3 performs such calculation for each track Tn. The position smoothing constant α and the speed smoothing constant β are set, for example, as shown in Table 1 according to the reliability value TQn of each track Tn.

[0044]

[Table 1]

FIG. 9 is a diagram showing a state of the position smoothing process. The predicted position DTn (t) of the track Tn obtained by the later-described prediction and the corresponding position D of the plot P
Pn (t), the predicted speed VTn (t) of the track Tn obtained by the prediction and the speed of the plot P corresponding thereto do not completely match. The reason is that there is a variation due to a change in the target movement.

Therefore, in this embodiment, the track Tn
Is high (TQn large), the smoothed position DS
The position smoothing constant α and the speed smoothing constant β are set so that n (t) and the smoothing speed VSn (t) are close to the predicted position DTn (t) and the predicted speed VTn (t) of the track Tn. .

Conversely, the reliability of the track Tn is low (TQ
n), the position smoothing constant α and the speed smoothing constant β are such that the smoothing position DSn (t) and the smoothing speed VSn (t) are close to the position DPn (t) and the speed of the plot P.
And. Thus, the current position and speed of the track Tn are determined from the predicted position and speed of the track Tn and the position of the plot P.

Next, the processing device 3 performs a target update process for updating the information of the track Tn stored in the memory 4 (step 105 in FIG. 2). FIG. 10 is a flowchart for explaining the target update processing.

First, the processing device 3 calculates the predicted position DTn (t + 1) of the track Tn at the next sweep as shown in the following equation (step 401 in FIG. 10). DTn (t + 1) = DSn (t) + VSn (t) × Δt (4) The processing device 3 performs such calculation for each track Tn. After the calculation, the processing device 3 calculates the predicted position DTn (t) of the track Tn stored in the memory 4 as DTn (t + 1).
Update to

Subsequently, the processing device 3 calculates the predicted speed VTn (t + 1) of the track Tn at the next sweep as shown in the following equation (step 402). VTn (t + 1) = VSn (t) (5) The processing device 3 performs such calculation for each track Tn. After the calculation, the processing device 3 calculates the predicted speed VTn (t) of the track Tn stored in the memory 4 as VTn (t + 1).
Update to

It should be noted that for the track Tn for which there is no correlation, that is, for which there is no corresponding plot P in the correlation determination processing of step 301, the smoothed position DS
Since n (t) and the smoothing speed VSn (t) cannot be obtained, the predicted position DTn (t) is used instead of the smoothed position DSn (t), and the predicted speed is used instead of the smoothed speed VSn (t). VTn (t) is used.

Next, the processing device 3 includes the own vehicle and the truck T
The collision prediction time tn indicating the time required for the collision of n is calculated for each track as in the following equation (step 403). tn = DTn (t + 1) / VTn (t + 1) (6) If the predicted collision time tn is a positive value, it indicates that the vehicle is going away from the host vehicle. To indicate that After the calculation, the processing device 3 stores the predicted collision time tn in the memory 4.

Next, the processing device 3 updates the reliability value TQn of each track Tn stored in the memory 4 (step 404). That is, for the track Tn having a correlation with the plot P, the processing device 3 sets the reliability value TQ
For example, n is increased by two. The maximum value of the reliability value TQn is 7, for example, and does not become larger than 7. In addition, the processing device 3 controls the track Tn having no correlation with the plot P.
For, the reliability value TQn is reduced by, for example, one. In addition,
The minimum value of the reliability value TQn is 0 and does not become smaller than 0.

Subsequently, the processing device 3 determines whether or not the updated reliability value TQn is 0 (step 405). If the updated reliability value TQn is 0, the processing device 3 stores the corresponding track Tn in the memory 4. (Step 406).

Next, the processing device 3 determines whether or not there is a decorrelation plot, that is, a plot P for which there is no corresponding track Tn (step 407). The plot P is stored in the memory 4 as a new track Tn (step 4).
08). At this time, the position DTn of the decorrelation plot P
(T) is the position of the new track Tn, and the reliability value TQn of this track Tn is, for example, 2. Since the new track is out of the display and alarm processing, there is no speed information, and the speed information can be obtained from the moving distance and the elapsed time at the next correlation. Thus, the target update processing ends.

Next, the processing device 3 updates the predicted position DTn (t + 1) of the track Tn and the predicted speed VT after the update.
An alarm generation process is performed based on n (t + 1) and the predicted collision time tn (step 106). FIG. 11 is a flowchart for explaining the alarm generation processing.

The predicted position DTn (t + 1) of the track Tn
Indicates the distance between the host vehicle and the truck Tn. Therefore, the processing device 3 calculates the predicted position DT of each track Tn.
It is determined whether n (t + 1) is less than or equal to a preset distance (step 501 in FIG. 11), and the predicted position DTn (t
Track Tn in which +1) is less than or equal to a preset distance
If there is, it is determined that there is a danger of collision, and an alarm sound or an alarm message notifying the occupant of the vehicle of the danger is output to the audio output device 6 (step 502).

Further, the predicted speed VTn (t
+1) indicates the relative speed between the own vehicle and the truck Tn. If the predicted speed VTn (t + 1) is a positive value, it indicates that the vehicle is separated from the own vehicle. Indicates approaching. Further, the predicted speed VTn (t
If the absolute value of +1) is, for example, within the range of the vehicle speed ± 10 km / h, the truck Tn can be regarded as a stationary target.

Therefore, the processing device 3 sets each track T
n is equal to or higher than a preset speed, that is, the predicted speed VTn (t + 1) is a negative value and the predicted speed VTn
It is determined whether or not the absolute value of (t + 1) is equal to or higher than a preset speed (step 503). If there is a track Tn whose approach speed is equal to or higher than the preset speed, there is a danger of collision. Upon making a determination, an alarm sound or an alarm message is output to the audio output device 6 (step 502).

If the predicted collision time tn is a positive value, it indicates that the vehicle is moving away from the host vehicle, and if the collision prediction time tn is a negative value, it indicates that the vehicle is approaching the host vehicle. Therefore, the processing device 3 determines whether or not the collision prediction time tn is a negative value and the absolute value of the collision prediction time tn is within a preset time (step 504). If there is a track Tn having a negative value and the absolute value of which is within a preset time, it is determined that there is a danger of collision, and an alarm sound or an alarm message is output to the audio output device 6 ( Step 502). Thus, the alarm generation processing ends.

Next, the processing device 3 performs a display process of the detection result. In this display processing, it is first determined whether or not the current time is the timing to be displayed (step 10).
7). The display cycle is set to one sweep or a predetermined time (for example, one second). If the current time is the timing to be displayed, the processing device 3 displays the detection result on the display device 5.
Display on the screen.

FIG. 12 is a diagram showing one display example of the detection result. FIG. 12A is a diagram showing a state where the envelope signal Env, the plot P, the 4-second history of the envelope signal Env, the 4-second history of the track Tn, and the like are displayed on the screen of the display device 5. FIG. 12B shows the predicted position DTn (t + 1) of the track Tn and the predicted speed VT on the screen of the display device 5.
It is a figure showing signs that n (t + 1), collision prediction time tn, reliability value TQ, etc. were displayed.

The above processing of steps 101 to 108 is repeated every time the trigger signal Trig is input, that is, every one sweep. In this embodiment, the case where the number of radars 1 is one is described.
In the case where there are a plurality of radars, similar processing may be performed for each radar.

Further, in the present embodiment, the detection result as shown in FIG. 12 is displayed on the screen of the display device 5, but when mounted on an actual vehicle, a simpler display form is better. preferable. FIG. 13 is a diagram showing another display example of the detection result. In the example of FIG. 13, the host vehicle and the radar mounted on the host vehicle are displayed at the center of the screen, and the targets detected by the respective radars are displayed around the host vehicle and the radar mounted on the host vehicle. The arrow added to the target indicates the predicted speed vector of the target. If the processing device 3 determines that there is a danger of collision in the warning generation process of step 106, the processing device 3 issues a warning by displaying the target in red, for example. At the same time, an alarm output from the audio output device 6 may be performed.

In this embodiment, a radar that emits an electromagnetic wave is used as a sensor for measuring a distance to an object, but a radar that emits and receives laser light may be used. However, in the present invention, it is necessary to scan around the vehicle over a wide range in order to detect an obstacle. When using electromagnetic waves, it is possible to scan over a wide range without moving the radar. On the other hand, since the laser beam has a sharp directivity, when using the laser beam, it is necessary to sweep and irradiate the laser beam over a predetermined angle, and a driving mechanism for this is required. Therefore, as an obstacle detection device for a vehicle,
It is preferable to use a radar that emits electromagnetic waves.

[Second Embodiment] The processing device 3 in the first embodiment can be realized by a computer.
A program for realizing the vehicle obstacle detection method of the present invention is provided in a state recorded on a recording medium such as a floppy disk, a CD-ROM, and a memory card. When this recording medium is inserted into the auxiliary storage device of the computer, the program recorded on the medium is read. Then, the CPU of the computer writes the read program in a RAM or a large-capacity storage device, and executes the processing described in FIG. 2 according to the program.
Thus, the same operation as that of the first embodiment can be realized.

[0067]

According to the present invention, the use of a radar that emits electromagnetic waves makes it possible to accurately detect a target irrespective of weather conditions and to reduce the probability of malfunction as compared to an ultrasonic sensor. . Further, it is possible to detect a long distance due to the nature of the electromagnetic wave, and it is possible to detect a relatively distant target from an early stage. In addition, a target that can be an obstacle is detected based on the detection result of the reflected wave, and the position of the target, the relative speed between the target and the own vehicle, and the predicted collision time between the target and the own vehicle are calculated in real time, and each target is Since the danger of the collision of the own vehicle is predicted and a warning is issued when there is a danger of the collision, a traffic accident can be prevented beforehand and the safety of the occupant can be improved.

For each sample value obtained by sampling the detection result of the reflected wave, a threshold value is calculated from sample values before and after the sample value, and a sample value exceeding the threshold value is extracted as a target, thereby facilitating the target. The cross-correlation between the tracked target detected in the previous radar scan and the newly detected target is determined, and the tracked target and the newly detected target are associated with each other. By determining the motion state of the target, the position of the target, the relative speed and the collision prediction time can be easily calculated, and by comparing the target position, the relative speed and the collision prediction time with the preset values, Thus, the risk of collision between the target and the host vehicle can be easily determined.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a vehicle obstacle detection device according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the vehicle obstacle detection device of FIG. 1;

FIG. 3 is a diagram showing a transmission waveform of a radar.

FIG. 4 is a flowchart illustrating a target detection process.

FIG. 5 is a signal waveform diagram for explaining a target detection process.

FIG. 6 is a signal waveform diagram for explaining a target detection process.

FIG. 7 is a flowchart illustrating a target tracking process.

FIG. 8 is a signal waveform diagram for describing a specific example of a correlation determination process.

FIG. 9 is a diagram illustrating a state of a position smoothing process.

FIG. 10 is a flowchart illustrating a target update process.

FIG. 11 is a flowchart illustrating an alarm generation process.

FIG. 12 is a diagram showing one display example of a detection result.

FIG. 13 is a diagram showing another display example of a detection result.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Radar, 2 ... A / D converter, 3 ... Processing device, 4 ... Memory, 5 ... Display device, 6 ... Sound output device.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01S 13/42 G01S 13/42 13/60 13/60 C 13/93 13/93 Z G08B 21/00 G08B 21/00 HF term (reference) 5C086 AA54 BA22 CA06 DA01 DA08 EA15 EA41 EA45 5H180 AA01 BB13 CC03 CC12 CC14 LL01 LL07 5J070 AB01 AB24 AC01 AC02 AC06 AE01 AF03 AH04 AH31 AK22 BF03 BF12

Claims (6)

[Claims] 1. A first procedure for detecting a reflected wave of an electromagnetic wave radiated from a small radar that can be mounted on a vehicle, and detecting a target that may be an obstacle based on a detection result of the reflected wave; A second procedure for calculating a relative speed between the target and the host vehicle and a predicted collision time between the target and the host vehicle; and a collision between the target and the host vehicle based on the target position, the relative speed, and the predicted collision time. A third procedure for predicting the danger of the vehicle and issuing an alarm when there is a danger of a collision. 2. The vehicle obstacle detection method according to claim 1, wherein the first step calculates a threshold value from sample values before and after each sample value obtained by sampling the detection result of the reflected wave. And extracting a sample value exceeding the threshold value as a target. The second procedure determines a cross-correlation between the tracked target detected in the previous radar scan and the newly detected target. And then associating the tracked target with the newly detected target, determining the motion state of each target, and calculating the target position, relative velocity, and predicted collision time. The procedure is a procedure of determining whether there is a risk of collision between the target and the host vehicle by comparing the position of the target, the relative speed, and the predicted collision time with preset values. Vehicle obstacles Object detection method. 3. A small-sized radar which can be mounted on a vehicle and emits an electromagnetic wave to detect a reflected wave, alarm output means for notifying that there is a danger of collision with an obstacle, and a reflected wave from the radar. Based on the detection result, a target that can be an obstacle is detected, and the position of the target, the relative speed between the target and the host vehicle, and the estimated collision time between the target and the host vehicle are calculated. Based on the calculation result, the target And a processing unit for predicting the danger of a collision of the vehicle and, when there is a danger of a collision, outputting an alarm to the alarm output unit. 4. The obstacle detecting device for a vehicle according to claim 3, wherein the processing unit calculates a threshold value from a sample value before and after each sample value obtained by sampling the detection result of the reflected wave, A sample value exceeding this threshold value is detected as a target, and the cross-correlation between the tracked target detected in the previous radar scan and the newly detected target is determined, and the tracked target and the newly detected target are determined. Are determined, the motion state of each target is determined, the position of the target, the relative speed and the estimated collision time are calculated, and the calculated result is compared with a preset value to thereby determine the target and the host vehicle. An obstacle detecting device for a vehicle, which determines whether or not there is a risk of collision. 5. A recording medium in which a vehicle obstacle detection program for detecting an obstacle around a vehicle is recorded, wherein a reflected wave of an electromagnetic wave radiated from a small radar mountable on the vehicle is detected, and the reflected wave is detected. A first procedure for detecting a target that can be an obstacle based on the wave detection result; and a second procedure for calculating a position of the target, a relative speed between the target and the host vehicle, and a collision prediction time between the target and the host vehicle. And a third procedure of predicting a danger of collision between the target and the host vehicle based on the position, relative speed, and predicted collision time of the target, and issuing an alarm if there is a danger of collision. Recording medium for recording a vehicle obstacle detection program to be executed by a vehicle. 6. The recording medium according to claim 5, wherein in the first step, a threshold value is calculated from sample values before and after each sample value obtained by sampling the detection result of the reflected wave. A step of extracting a sample value exceeding a threshold value as a target, wherein the second step is to determine a cross-correlation between a tracked target detected in the previous radar scan and a newly detected target, and perform tracking. Is a procedure of associating the target with the newly detected target, determining the motion state of each target, and calculating the position, relative speed and collision prediction time of the target. The third procedure is A recording medium, which is a procedure for determining whether or not there is a risk of collision between the target and the host vehicle by comparing a target position, a relative speed, and a predicted collision time with preset values.