JP2003057345A - Ranging device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a threshold on the level of a received electric signal corresponding to an outgoing angle of a laser beam. SOLUTION: When a running state determination part 32 determines that the running state of a vehicle is a stable state, a distance calculation part 33 calculates the distance from an outgoing means 1 to the road surface based on time data of a reflected wave determined to be effective as a reflected wave from the road surface, and an outgoing angle calculation part 34 calculates the present outgoing angle of the laser beam based on the distance. A threshold setting means 4 sets the threshold for determining to be a received reflected wave or not on reference to a threshold table 52 based on the outgoing angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle distance measuring device for measuring a distance between a vehicle and an object to be measured.

[0002]

2. Description of the Related Art In a vehicle distance measuring device of this type, a laser beam is emitted from a vehicle to a distance measuring object, and the laser beam reflected by the distance measuring object is received and emitted. It is known to measure the distance between the host vehicle and the object to be measured based on the time from reception to reception of the wave. The laser light is emitted with a width of a predetermined angle θ2 toward the emission angle θ1 direction along the vertical direction of the vehicle. The laser light emitted in this manner will be received again as a reflected wave, and the received reflected wave includes the reflected wave reflected from the object to be measured,
The reflected wave reflected from the road surface is included. Of these reflected waves, the information directly used to measure the distance to the object to be measured is the former, and the latter reflected waves from the road surface and those from the object to be measured are distinguished. It must be.

Conventionally, in order to distinguish the reflected wave from the road surface and the reflected wave from the object to be measured, a threshold value for the intensity of the received reflected wave is set, and the reflected wave having an intensity equal to or higher than this threshold value is set. The reflected wave from the distance measuring object is determined, and the distance to the distance measuring object is measured using only the information related to the reflected wave from the determined distance measuring object. The error due to was prevented and the accuracy of distance measurement was maintained.

[0004]

However, if the emitting angle of the laser light changes due to the change in the mounting position of the emitting device that emits the laser light due to deterioration over time or mounting error, the intensity level of the reflected wave from the road surface will change. There is a problem that a change occurs and it becomes impossible to discriminate the reflected wave from the object to be measured with the set threshold value.
For example, when the emission direction of the laser light is downward from a predetermined emission angle, the reflected wave level from the road surface is high, and when it is upward, the reflected wave level from the road surface is low. The relationship between the output angle and the intensity of the reflected wave is specifically shown in FIG. Graph A shown in FIG. 4 is the intensity level of the reflected wave when the emission angle is shifted downward from the predetermined angle, graph B is the intensity level of the reflected wave when the emission angle is the predetermined angle, and graph C is shown. Is the intensity level of the reflected wave when the emission angle deviates upward from the predetermined angle. In this way, the reflected wave level changes according to the change in the emission angle of the laser light. Therefore, if an absolute threshold value is set based on a certain state (a state where the emission angle is downward), another state (the emission angle is (Predetermined angle or upward)
In the above, the threshold value is too large, and the reflected wave from the object to be measured and the reflected wave from the road surface cannot be accurately discriminated, and the distance to the object to be measured cannot be accurately measured. there were.

The present invention has been made in view of the above-mentioned problems of the prior art, and by setting an appropriate threshold value relative to the emission direction of the electromagnetic wave, the distance to the object to be measured. An object of the present invention is to provide a distance measuring device for a vehicle that accurately measures

[0006]

(1) In order to achieve the above object, according to the invention of claim 1, the electromagnetic wave emitted from the vehicle is reflected based on a reflected wave from an object to be measured. A distance measuring device for a vehicle for measuring a distance between a host vehicle and the object to be measured, wherein the emitting means emits an electromagnetic wave from the vehicle to the object to be measured, and a reflected wave of the emitted electromagnetic wave. Of the emitted electromagnetic wave,
Emission angle calculation means for calculating the emission angle in the vehicle vertical direction with respect to an arbitrary reference axis, threshold setting means for setting a threshold value based on the emission angle calculated by the emission angle calculation means, and the received reflected wave When the intensity of the reflected wave received is equal to or higher than the threshold value set by the threshold value setting means, the comparison result by the comparison means for comparing the intensity of the above with the threshold value set by the threshold value setting means, and the comparison result by the comparison means. The determining means for determining that the reflected wave received by the wave receiving means is the reflected wave from the object to be measured,
Distance measurement for measuring the distance between the own vehicle and the distance measurement object based on the reflected wave received by the wave reception means when the determination result by the determination means is a reflected wave from the distance measurement object Provided is a vehicle distance measuring device having means. In this invention, the emission angle calculation means calculates the distance of the optical path from the emission means to the road surface calculated from the timing of emitting the electromagnetic wave and the timing of receiving the electromagnetic wave, and the height from the road surface of the emission means. It is preferable to calculate the emission angle based on the above (claim 2).

In the present invention, the emission angle calculation means calculates the emission angle in the vehicle up-down direction with respect to an arbitrary reference axis with respect to the optical axis of the electromagnetic wave emitted from the emission means, and based on the calculated emission angle, By setting the threshold value, the threshold value corresponding to the current emission angle is set. This set threshold serves as a reference for determining whether or not the reflected wave is the reflected wave from the object to be measured. The emission angle that is the basis for setting the threshold value can be calculated based on the distance along the optical path of the electromagnetic wave from the emission means to the reflection position on the road surface and the height of the emission means with respect to the road surface.

In the present invention, the reference axis defining the emission angle is set in advance, and the emission angle is the vertical direction of the vehicle with respect to this reference axis (the vertical direction along the direction of gravity the vehicle receives in a running state). The angle formed by the emitted electromagnetic wave is the angle formed by the reference direction and the direction in which the electromagnetic wave is actually emitted.

With this, the optimum threshold value can be set according to the emission angle of the electromagnetic wave actually emitted from the vehicle, the reflected wave from the object to be measured can be accurately determined, and based on the accurately determined reflected wave. Since it is possible to measure the distance to the object to be measured, it is possible to provide a highly accurate vehicle distance measuring device. Further, the state of the reflected wave changes depending on the weather and the road surface state, but the vehicle distance measuring device of the present invention can set the threshold value in response to such a change, and therefore it depends on the receiving environment. It is possible to eliminate the influence and provide a highly accurate range finder.

(2) In order to achieve the above object, according to the invention described in claim 3, there is provided a traveling state detecting section for detecting a traveling state of the own vehicle, and the emission angle calculating means has the traveling state detecting section. There is provided a vehicle distance measuring device that calculates the emission angle according to the traveling state detected by the state detection unit and sends it to the threshold value setting means. In this invention, the traveling state detection unit may detect a steering angle of the host vehicle, and the emission angle calculation means may calculate the emission angle when the detected steering angle is equal to or less than a predetermined angle. Preferably (Claim 4), the traveling state detection unit detects an acceleration or deceleration of the host vehicle, and the emission angle calculation unit determines that the detected acceleration or deceleration is a predetermined acceleration or deceleration. It is preferable to calculate the emission angle in the following cases (claim 5). Further, the traveling state detection unit may detect a gradient of a road surface on which the host vehicle travels, and the emission angle calculation means may calculate the emission angle when the detected gradient is equal to or less than a predetermined gradient. Preferred (Claim 6).

According to the present invention, the traveling state detecting section detects the traveling state of the host vehicle and calculates the emission angle according to the detection result. In addition, the detection of the traveling state is performed from the viewpoint of the amount of change in steering angle, acceleration or deceleration, and / or the slope of the road surface. For example, when the amount of change in steering angle is smaller than a predetermined value, the acceleration or deceleration is smaller than a predetermined value, and / or the slope of the road surface is smaller than a predetermined value,
It is determined that the traveling state of the vehicle is stable, and the emission angle of the subject vehicle is calculated according to the detection result. In other words, when the vehicle is turning, accelerating or decelerating, or traveling on a sloping road surface, the distance between the emitting means and the road surface cannot be accurately calculated from the reflected wave from the road surface. Is not set.

With this, in the moving vehicle, when the threshold value for determining whether the reflected wave is the reflected light from the object to be measured, the emission angle is set when the traveling state of the vehicle is stable. From this, it is possible to set the threshold value according to the highly reliable emission angle.By the threshold value set in this way, the reflected wave from the object to be measured can be accurately determined and accurately determined. Since the distance to the object to be measured can be measured based on the reflected wave, it is possible to provide a highly accurate vehicle distance measuring device.

[0013]

According to the invention of claim 1 or 2, the optimum threshold value can be set according to the emission angle of the electromagnetic wave actually emitted from the vehicle, and the reflected wave from the object to be measured can be accurately determined. However, since the distance to the object to be measured can be measured based on the accurately determined reflected wave, it is possible to provide a highly accurate vehicle distance measuring device. Further, the state of the reflected wave changes depending on the weather and the road surface state, but the vehicle distance measuring device of the present invention can set the threshold value in response to such a change, and therefore it depends on the receiving environment. Eliminate the impact,
It is possible to provide a highly accurate distance measuring device.

According to the invention described in claims 3 to 6, in setting the threshold value for determining whether or not the reflected wave is the reflected light from the object to be measured in the moving vehicle, Since the emission angle is calculated when the traveling condition is stable, it is possible to set the threshold value according to the highly reliable emission angle, and the reflected wave from the object to be measured can be set by the threshold value set in this way. Since the distance to the object to be measured can be accurately determined and the distance to the distance measurement object can be measured based on the accurately determined reflected wave, it is possible to provide a highly accurate vehicle distance measuring device.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is a vehicle distance measuring device 100.
For example, it has a function of calculating the inter-vehicle distance between the own vehicle, the preceding vehicle, and the obstacle, and presenting the calculated inter-vehicle distance to the user. To outline this function, follow the driving instruction,
Electromagnetic waves are emitted from the emitting means 1, and a predetermined threshold value is set based on the steering angle, vehicle speed, throttle opening, and engine speed detected by each sensor, and the receiving means 2 uses the set threshold value as a reference. From the received electric signal, it is determined whether or not it is a reflected wave from the object to be measured, and based on the electric signal, the steering angle, and the vehicle speed based on this reflected wave, the own vehicle and the preceding vehicle are measured. The distance to the distance object is calculated, and the calculation result is presented to the user via the external device 7.

FIG. 1 is a block diagram showing the structure of a vehicle distance measuring device 100 according to an embodiment of the present invention. As shown in FIG. 1, a vehicle distance measuring apparatus 100 according to the present embodiment includes an emitting unit 1, a wave receiving unit 2, a wave receiving determining unit 21, an emitting angle calculating unit 3, a threshold setting unit 4, It has a storage means 5, a distance measuring means 6, and an external device 7. These configurations operate by transmitting and receiving data to and from each other, but can be functionally divided into four blocks as follows.

Specifically, the validity of the data is judged by radiating the electromagnetic wave and judging whether the received electromagnetic wave is the reflected wave from the road surface or the reflected wave from the object to be measured. A first block, a second block for storing various necessary data, a third block for detecting the traveling state of the vehicle, and a third block for calculating the emission angle based on the data determined to be effective, And a fourth block for setting a threshold value based on the output angle thus obtained. For convenience of description, each configuration will be described along this section.

First, a configuration relating to transmission / reception of electromagnetic waves positioned in the first block, determination of reflected waves, and determination of effectiveness of reflected waves will be described. Here, the emitting unit 1, the wave receiving unit 2, the filter unit 211 of the wave receiving determining unit 21, the continuity determining unit 212, the light transmitting / receiving time determining unit 213, the level determining unit 214, and the validity determining unit 22 will be described.

The emitting means 1 is provided in the front portion of the vehicle and emits electromagnetic waves toward the front of the vehicle (direction of the object to be measured) with a predetermined angle (for example, 4 degrees).
The emitted electromagnetic waves are radio waves and light (infrared rays, visible light,
The phenomenon in which electromagnetic field vibrations such as ultraviolet rays, X-rays, γ-rays) are transmitted, and those used as in-vehicle radar devices include
There are laser radars and radio wave radars that use infrared light.
The output waveform is not limited and may be pulse output or continuous output. In this embodiment, distance measurement is performed using laser light. When the laser light emitted from the emitting means 1 collides with an object to be measured in front of the vehicle or a road surface, a reflected wave is generated. The wave receiving means 2 receives this reflected wave, converts it into an electric signal, and sends it out to the wave reception judging means 21.

The vehicle distance measuring device 100 according to the present embodiment.
Regarding the radar method in distance measurement, a pulse method that transmits a short-time pulse signal and detects the distance from the delay time until the reflected wave from the target in front is received, or a continuous wave that is frequency-modulated with a triangular wave is transmitted. , An FM-CW method of detecting a delay time from a frequency of a reflected wave from a forward distance measurement object and a transmission frequency difference at the time of reflection reception, and calculating a distance from this information, a transmission direction of a transmission signal in a horizontal direction or / Also, there is a scanning method in which transmission is performed while moving in the vertical direction. In this embodiment, any method can be adopted and there is no particular limitation. However, the scanning-type vehicle distance measuring device 1
When 00 is adopted, it is necessary to apply the present embodiment with the optical axis of the lowermost laser beam in the scanning range as a reference.

The reception determination means 21 includes a comparison means and determination means of the invention according to the present application, and includes a filter section 211, a continuity determination section 212, a level determination section 214, and a transmission / reception time determination section 213. Have Also, the reception determination means 21
Also has a function of controlling the emitting means 1 and the receiving means 2,
Time data regarding the time from the emission of laser light to the reception of laser light is acquired. Based on this time data and the electric signal information received from the wave receiving means 2, it is determined whether or not the reflected wave is reflected from the object to be measured. That is, the received wave determination means 21 determines whether the reflected wave received from the viewpoints of the intensity of the reflected wave, the transmission / reception time, and the continuity is a reflected wave from the object to be measured or a reflected wave from the road surface. Determine if there is, and distinguish between these.

Each configuration will be specifically described. The filter unit 211 mainly performs the functions of the comparing unit and the determining unit according to the present application, refers to the threshold value table 52 of the storage unit 5 described later, and calculates the threshold value calculated by the threshold value setting unit 4 according to the emission angle. Based on the above, it is determined whether or not the level of the electric signal of the reflected wave received from the wave receiving means 2 is equal to or higher than the set threshold value, and if the level of the electric signal is less than the threshold value, there is a possibility of the reflected wave from the road surface. If it is equal to or more than the threshold value, it is determined that it is a reflected wave from the object to be measured. In this way, according to the judgment of the filter unit 211, if the level of the electric signal is equal to or higher than the threshold value (if it is the reflected wave from the object to be measured), the acquired time data is sent to the relative speed confirmation unit 8 and the electric signal level is If it is less than or equal to the threshold value (if it is a reflected wave from a road surface or the like), the time data and the electric signal based on the reflected wave from the object to be measured are sent to the continuity determination unit 212.

The continuity determining section 212 determines the continuity of the reflected wave. That is, when a reflected wave from a distance-measuring object such as a preceding vehicle is received, the time data should have continuity. Conversely, when a reflected wave from the road surface is received. The time data should have discontinuity due to uneven reflectance and fine unevenness of the road surface. Utilizing this characteristic, the continuity determining unit 212 determines that the reflected wave is from the object to be measured when the time data has continuity. In this way, when the continuity determination unit 212 determines that there is continuity (it can be determined that it is a reflected wave from the object to be measured), the time data is sent to the relative speed confirmation unit 8 and there is no continuity ( If it is possible to determine that the reflected wave is from something other than the object to be distance-measured), the time data is sent to the light transmission / reception time determination unit 213 and the validity determination unit 22, and the electric signal is sent to the level determination unit 214.

The transmission / reception time determination unit 213, to which the time data regarding the reflected wave determined to have no continuity, that is, the reflected wave from the road surface other than the object to be measured is sent, has the time data within a predetermined range. If it is within a predetermined time, it is determined that it is a reflected wave from the road surface, and if it is outside the predetermined time, it is determined that it is not a reflected wave from the road surface. This determination result is sent to the validity determination unit 22. In addition, the level determination unit 214 to which the electric signal regarding the reflected wave that is determined to be the reflected wave that is not continuous, that is, the wave other than the object to be measured is sent, has the electric signal level within a predetermined range. Determine whether or not. If the level is within a predetermined range, the reflected wave is an electric signal based on the reflected wave from the road surface, and if the level is outside the predetermined range, the reflected wave is not an electric signal based on the reflected wave from the road surface. You can judge. The result of this judgment is sent to the validity judging section 22. The predetermined range of the level of the electric signal is set to a range equal to or less than the maximum value of the reflection level from the road surface obtained by the experiment and equal to or more than the minimum value.

The validity determining unit 22 determines the continuity determining unit 21 based on the determination results of the running condition determining unit 32, the level determining unit 214, and the light transmitting / receiving time determining unit 213, which will be described later.
The validity of the time data sent from No. 2 is judged, and when it is judged that the time data is valid, the judgment result is sent to the distance calculation unit 33.

The storage means 5 positioned as the second block has a calculation result storage area 51 for temporarily storing the calculated emission angle described above, and stores the emission angle and the threshold value of the level of the electric signal. The associated threshold value table 52, information 53 about the height of the emitting means 1 and other information necessary for distance measurement are stored. Here, the threshold table 5
2 will be described. The threshold value table 52 is information referred to when the threshold value setting means 4 sets a threshold value according to the calculated emission angle, and can be stored in the threshold value setting means 4. More specifically, this threshold value table 52 associates the emission angle with the threshold value. Is this threshold value a reflected wave from the distance measurement target object among the received reflected waves? It may be any value that serves as a reference for determining whether or not it includes, for example, the intensity of the reflected wave, the level of the electric signal based on the reflected wave, and the like. This threshold table 52
Is associated with an appropriate threshold for each emission angle,
Since it is preferable to cover all the emission angles that the emission means 1 can take, it is preferable that the emission means 1 be created with a smaller emission angle interval in a wide range. However, when the threshold table 52 is created at a predetermined interval (for example, every 3 ° of emission angles), the calculated values of the emission angles are processed and the threshold table 52 of the most approximated value is accessed. There is a need. The emission angle is an angle formed by the emission optical axis of the laser light with respect to a preset reference optical axis unique to the vehicle.

This threshold value is previously obtained by an experiment,
It is preferably stored in the storage means 5. Further, the threshold value can be set arbitrarily, and at least it is necessary to be a threshold value capable of discriminating the reflected wave from the distance measuring object among the reflected waves, and preferably the reflected wave from the distance measuring object and the road surface. A threshold is set so that it can be distinguished from the reflected wave. In the present embodiment, the threshold value is set so that the reflected wave from the object to be measured can be discriminated and the reflected wave from the road surface can be distinguished.

Next, the structure relating to the calculation of the emission angle including the emission angle calculation means 3 positioned as the third block will be described. Here, the steering angle sensor 301, the vehicle speed sensor 302, the throttle opening sensor 303, the engine speed sensor 304, the traveling state detection unit 31 that receives information detected by these, the traveling state determination unit 32 of the emission angle calculation unit 3, and the distance. Calculation unit 33, emission angle calculation unit 34,
In addition, the distance measuring unit 6, the relative speed confirmation unit 8, and the external device 7 will be described. First, as a sensor for detecting the state of the vehicle, the vehicle range finder 100 according to the present embodiment includes a steering angle sensor 301, a vehicle speed sensor 302, and a throttle opening sensor 3.
03, engine speed sensor 304, corresponding to these, the traveling state detection unit 31 for processing information about the traveling state of the vehicle based on the detection result, the straight traveling determination function 31.
1, it has an acceleration / deceleration determination function 312 and a gradient determination function 313.

Specifically, the steering angle sensor 301 detects the steering angle of the vehicle, and sends the detected steering angle to the straight-ahead judgment function 311. The straight-ahead judgment function 311 indicates that the steering angle is a predetermined angle or less (for example, 3 °). The following) is determined. Accordingly, it is possible to determine the state of the vehicle such as whether the vehicle is traveling straight or turning. The vehicle speed sensor 302 calculates the traveling speed of the vehicle, and the calculated result is used as the acceleration / deceleration determination function 31.
Then, the acceleration / deceleration determination function 312 determines whether the vehicle has a predetermined acceleration or deceleration (for example, 0.3 m / s ² or less). Thereby, the state of the vehicle such as whether the vehicle is traveling at an acceleration or deceleration or at a constant speed can be determined. The throttle opening sensor 303 detects the throttle opening, the engine speed sensor 304 detects the engine speed, and sends the detection results to the slope determination function 313. The slope determination function 313 detects the running resistance. The slope of the traveling road surface is calculated and estimated, and it is determined whether the slope is equal to or less than a predetermined slope reference value. This makes it possible to determine the state of the vehicle such as whether the vehicle is traveling on a sloped road surface or a flat road surface. In this way, the state of the vehicle is detected when the vehicle is being accelerated or decelerated, when the vehicle is turning, or when the vehicle is traveling on a sloping road surface, it is mounted on the vehicle. The shortest distance between the emitting device 1 and the road surface is not a constant value,
This is because it is considered that the timing for measuring the emission angle is not appropriate, and therefore the emission angle is not measured in such a state.

Each of these judgment results is used as a running condition judging unit 32.
When all the determination results are equal to or less than a predetermined value, that is, the results indicate a stable state, the traveling state determination unit 32 determines that the vehicle state is stable, and the validity determination unit 32 determines this determination result. 22 to be sent. In the present embodiment, if at least one of the determination results of the three determination functions is a predetermined value or more, that is, the result indicates an unstable state, it is determined that the vehicle state is not stable, and this determination result is It is sent to the validity judging section 22. However, this combination is arbitrary, and it is not always necessary to activate all three determination functions. The effectiveness determination unit 22 that has obtained the determination result in this way
As described above, the determination result of the traveling state determination unit 32, the level determination unit 214, and the light transmission / reception time determination unit 21.
Based on the determination result of No. 3, the validity of the time data sent from the continuity determination unit 212 is determined.

The validity judging section 22 sends the time data judged to be valid to the distance calculating section 33, and
The distance calculator 33 calculates the distance a0 of the optical path to the position α at which the electromagnetic wave emitted from the emitting means 1 hits the road surface and is reflected based on this time data. The calculation method will be described together with the operation. This calculation process is repeated at a predetermined timing, and the distance a0 calculated repeatedly is the calculated distance storage area 5 of the storage means 5.
Stored in 1. The calculated distance storage area 51 of the storage unit 5
Stores a plurality of calculated distances a0, and when this value becomes N or more, the most appropriate value among the N values as the calculation result, for example, the distance with the highest calculation frequency is calculated as a0. Is output to the emission angle calculation unit 34.

The emission angle calculation unit 34 calculates the emission angle of the electromagnetic wave from the emission means 1 based on the received distance a0 and sends it to the threshold value setting means 4. The threshold value setting means 4 sets a threshold value by referring to the threshold value table 52 on the basis of the transmitted emission angle, and sets the set threshold value in the filter unit 2.
Send to 11. The filter unit 211 having received this divides the received reflected wave based on the sent threshold value into a reflected wave from the distance measuring object and a reflected wave from other than the distance measuring object.

The filter unit 211 discriminates the reflected wave from the object to be distanced among the received reflected waves, and sends the time data regarding the reflected wave to the distance measuring means 6 and the relative speed confirmation unit 8. The distance measuring means 6 that has acquired the time data calculates the distance between the host vehicle and the object to be measured based on this time data. The means for calculating the distance between the host vehicle and the object to be measured is not particularly limited, and any known means can be applied.

Further, the relative speed confirmation unit 8 calculates the relative speed between the host vehicle and the object to be measured based on the acquired time data. Further, the relative speed confirmation unit 8 uses the vehicle speed sensor 3
The vehicle speed detected by 02 and the steering angle detected by the steering angle sensor 301 are read, and based on the vehicle speed, the steering angle, and the calculated relative speed, whether or not the object to be measured is a preceding vehicle. To judge. This judgment is output to the external device 7 together with the calculated distance to the object to be measured.

The method of determining whether or not the distance-measuring object whose distance has been calculated is the preceding vehicle will be described below. The calculated relative speed between the own vehicle and the distance-measuring object and the own-vehicle. If they are the same, it can be determined that the target object is a stationary object, and if they are different, it can be determined that the target object is a preceding vehicle. Further, by comparing the position direction of the object to be measured with respect to the own vehicle and the steering angle detected by the steering angle sensor 301, if these are the same, the object to be measured is on the traveling lane of the own vehicle. It can be determined that they exist, and if they are not the same, it can be determined that the object to be measured does not exist on the traveling lane of the host vehicle. This result is output to the external device 7 together with the distance to the object for distance measurement calculated in advance.

Next, the configuration relating to the function of setting the threshold value based on the calculated emission angle, which is positioned as the fourth block, will be described. Here, the threshold setting means 4 will be described. The threshold value setting means 4 refers to the threshold value table 52 based on the emission angle calculated by the emission angle calculation unit 34 and sets a threshold value regarding the level of the electric signal according to the emission angle. The set threshold value may be stored in the storage unit 5 and accessed from the filter unit 211, or the threshold value may be directly sent to the filter unit 211.
When setting the threshold value, the reference emission angle is determined by the steering angle sensor 301 and the vehicle speed sensor 30 of the traveling state detection unit 31.
2, the running state determination unit 32 based on the detection results from the throttle opening sensor 303 and the engine speed sensor 304
Since it is calculated when it is determined that the traveling state is stable, the threshold value set based on this emission angle is highly reliable and can be said to be an appropriate threshold value for the vehicle. .

As described above, following the description of each configuration, FIG.
The basic operation will be described with reference to. This operation repeats activation at predetermined intervals (for example, every 50 msec) according to the activation command. First, the effectiveness determination unit 22 selects, from the reflected waves received by the wave receiving unit 2, based on the determination results of the filter unit 211, the continuity determination unit 212, the light transmission / reception time determination unit 213, and the level determination unit 214. If the electrical signal is less than or equal to the threshold value, the value of the time data determined by the light transmission / reception time determination unit 213 is within a predetermined range, and the time data determined by the continuity determination unit 212 is When there is no continuity and the level determination unit 214 determines that the level of the reflected wave is within a predetermined range, the continuity determination unit 21
It is determined that the time data received from No. 2 is valid time data (step 101), and the process proceeds to step 102. On the other hand, if it is not determined that the data is valid, the validity of the time data is determined again. In step 102, the validity determination unit 22 obtains information on whether or not the vehicle is traveling stably based on the determination result of the traveling state determination unit 32.
If a result that the vehicle is determined to be traveling stably is obtained, the process proceeds to step 103. If the vehicle is not traveling stably, time data is acquired again and its effectiveness is determined.
The time data for which the validity is determined is sent to the distance calculation unit 33, and the distance calculation unit 33, based on this time data,
The distance of the optical path from the emitting means 1 to the reflection position on the road surface (see FIG.
The distance indicated by middle a0) is calculated (step 103).
The calculated distance is sequentially sent to the calculated distance storage area 51 and temporarily stored therein (step 104).
In the calculated distance storage area 51, the number of stored distance values is counted. When this value becomes N or more (for example, 10 or more), the process proceeds to step 106, and the operations from step 103 are repeated until then (step 10).
5). When the values of N distances are stored, the value of the distance having the highest calculation frequency is selected from the N distances stored in the calculation means storage area 51, and this value is sent to the emission angle calculation unit 34. (Step 106). The emission angle calculation means 34 that has received the distance of the optical path from the emission means 1 to the reflection position of the road surface calculates the emission angle of the laser light with respect to the reference axis of the vehicle (step 107).

Here, a method of calculating the emission angle of the laser light will be described with reference to FIG. The vehicle shown in FIG. 3 is equipped with a vehicle distance measuring device 100, and the emitting means 1 for emitting laser light is provided at a position of height h. The laser light shown by the solid line is emitted from the emitting means 1, and the central optical axis thereof is R2. On the other hand, the reference optical axis that serves as a reference for emitting the laser light is R1 shown by the dotted line. The angle formed by the actual optical axis R2 with respect to the reference optical axis R1 is θa.

This laser light is emitted in the direction of R2 with a spread of the angular width of θw in the vertical direction (in the vertical plane) of the vehicle shown in FIG. The position where the lower laser light hits the road surface in the emitted laser light is α. The distance along the optical path of the laser light from the emitting means 1 to the position α is indicated by a0. The distance between the position of the wave receiving means 2 provided at the front of the vehicle with respect to the road surface and the position α on the road surface is indicated by a1.

Here, considering the angle θa of the actual optical axis R2 with respect to the reference optical axis R1, it can be expressed as θa = tan ⁻¹ (h / a1) −θw / 2. However, it is preferable that the reference optical axis R1 is substantially parallel to the road surface. Further, usually, a1 is a large value of about 30 m, and θw is a small value of about 4 °, so that the difference between a1 and a0 can be ignored. Therefore, by approximating this, θa = tan ⁻¹ (h / A0) -θw / 2. Thus, the distance from the emitting means 1 to the reflection position on the road surface calculated by the distance calculating section 33, the height h of the emitting means 1 stored in the storage means 5, and the angle of emission of the laser light in the vertical direction of the vehicle. The current emission angle of the laser light of the vehicle can be calculated based on a known value such as the width.

Based on the emission angle calculated in this way, the threshold setting means 4 refers to the threshold table 52 to set a threshold value according to the current emission angle, and this is stored in the storage means 5.
To the storage unit or the filter unit 211 (step 10
8) The above process is repeated. In the present embodiment, the threshold value is set to be calculated by referring to the threshold value table 52, but the present invention is not limited to this, and the threshold value setting means 4 calculates the threshold value according to the emission angle (calculation formula). Etc.) and the threshold value may be set accordingly.

As described above, the vehicle distance measuring apparatus 100 according to this embodiment sets the optimum threshold value according to the emission angle of the laser beam actually emitted from the vehicle, and reflects from the object to be measured. Since the waves can be accurately discriminated and the distance to the distance measurement object can be measured based on the accurately discriminated reflected waves, it is possible to provide the vehicle distance measuring apparatus 100 with high accuracy. In addition, in the moving vehicle, when setting the threshold value for determining whether the reflected wave is the reflected light from the object to be measured in the reflected wave, the emission angle is calculated when the traveling state of the vehicle is stable. Therefore, the threshold value can be set according to the highly reliable emission angle.

Further, for example, the state of the reflected wave changes when it rains or snows, but according to the vehicle distance measuring device 100, the threshold value can be set in response to such a change, so the receiving environment It is possible to eliminate the influence of and to maintain accuracy.

The embodiments described above are described for facilitating the understanding of the present invention, and not for limiting the present invention. Therefore, each element disclosed in the above-described embodiment is intended to include all design changes and equivalents within the technical scope of the present invention.

[Brief description of drawings]

FIG. 1 is a block diagram of a vehicle distance measuring device according to an embodiment.

FIG. 2 is a flow chart showing the operation of the vehicle distance measuring device according to the present embodiment.

FIG. 3 is a diagram for explaining a method of calculating an emission angle.

FIG. 4 is a diagram showing a relationship between an emission angle and a level of a reflected wave.

[Explanation of symbols]

100 ... Distance measuring device for vehicle 1 ... Emitting means 2 ... Receiving means 21 ... Receiving judgment means (comparing means, judging means) 211 ... Filter section 212 ... Continuity determination unit 213 ... Transmission / reception time determination unit 214 ... Level determination unit 22 ... Effectiveness judgment section 3 ... Emission angle calculation means 31 ... Running state detector 311 ... Straight ahead judging function 312 ... Acceleration / deceleration determination function 313 ... Gradient determination function 32 ... Running condition determination unit 33 ... Distance calculation unit 34 ... Emission angle calculation unit 301 ... Rudder angle sensor 302 ... Vehicle speed sensor 303 ... Throttle opening sensor 304 ... Engine speed sensor 4 ... Threshold setting means 5 ... storage means 51 ... Calculated distance storage area 52 ... Threshold table 53 ... Height information of emitting means 6 ... Distance measuring means 7 ... External device 8… Relative speed confirmation section

Claims (6)

[Claims] 1. A vehicle distance measuring device for measuring a distance between the own vehicle and the distance measuring object based on a reflected wave of an electromagnetic wave emitted from the own vehicle from the distance measuring object, comprising: An emitting unit that emits an electromagnetic wave from the host vehicle toward the object to be measured, a wave receiving unit that receives a reflected wave of the emitted electromagnetic wave, and a vehicle vertical direction of the emitted electromagnetic wave with respect to an arbitrary reference axis In the output angle calculation means for calculating the output angle in, the threshold setting means for setting a threshold value based on the output angle calculated by the output angle calculation means, the intensity of the received reflected wave and the threshold setting means Comparing means for comparing the set threshold value, the comparison result by the comparing means, when the intensity of the reflected wave received is equal to or more than the threshold value set by the threshold setting means, by the receiving means A determining unit that determines that the reflected wave that has struck is a reflected wave from the distance measuring object; and if the determination result by the determining unit is a reflected wave from the distance measuring object, the wave receiving unit receives the wave. A vehicle distance measuring device having a distance measuring means for measuring the distance between the vehicle and the object to be measured based on the reflected wave. 2. A distance from the emitting means to a road surface calculated from the timing of emitting the electromagnetic wave and the timing of receiving the electromagnetic wave, and the height of the emitting means from the road surface. The vehicle ranging device according to claim 1, wherein the emission angle is calculated based on 3. A traveling state detecting section for detecting a traveling state of the own vehicle, wherein the emission angle calculating means calculates the emission angle according to a traveling state detected by the traveling state detecting section, The vehicle distance measuring device according to claim 1 or 2, wherein the distance measuring device transmits the threshold value setting means. 4. The traveling state detection unit detects a steering angle of the host vehicle, and the emission angle calculation unit calculates the emission angle when the detected steering angle is equal to or less than a predetermined angle. Item 3. The vehicle distance measuring device according to item 3. 5. The traveling state detection unit detects an acceleration or deceleration of the host vehicle, and the emission angle calculation means determines that the detected acceleration or deceleration is equal to or less than a predetermined acceleration or deceleration. The vehicle distance measuring device according to claim 3, wherein the emission angle is calculated. 6. The traveling state detection unit detects a slope of a road surface on which the host vehicle travels, and the emission angle calculation means calculates the emission angle when the detected slope is less than or equal to a predetermined slope. Claims 3 to 5
The vehicle distance measuring device described.