JP3411866B2 - Millimeter wave radar device - Google Patents

Millimeter wave radar device

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Publication number
JP3411866B2
JP3411866B2 JP30255999A JP30255999A JP3411866B2 JP 3411866 B2 JP3411866 B2 JP 3411866B2 JP 30255999 A JP30255999 A JP 30255999A JP 30255999 A JP30255999 A JP 30255999A JP 3411866 B2 JP3411866 B2 JP 3411866B2
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Japan
Prior art keywords
vehicle
wave radar
millimeter wave
reflection
distance
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JP30255999A
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Japanese (ja)
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JP2001124848A (en
Inventor
満 中村
杰 白
由博 道口
和朗 高野
浩司 黒田
Original Assignee
株式会社日立カーエンジニアリング
株式会社日立製作所
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Publication of JP2001124848A publication Critical patent/JP2001124848A/en
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Publication of JP3411866B2 publication Critical patent/JP3411866B2/en
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Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-vehicle distance alarm and an AC
Millimeter-wave laser used for C (Adaptive Cruise Control)
Device. 2. Description of the Related Art An inter-vehicle distance warning device is disclosed in, for example,
As stated in the publication 66496,
The distance between the vehicle and the obstacle is measured by some distance measurement sensor.
Detects and alerts the driver when approaching too much.
This is a device that calls attention to Eva. [0003] ACC (Adaptive Cruise Control)
Is described in, for example, JP-A-11-39586.
In this way, the set distance between the vehicle and the preceding vehicle is maintained.
This is a device that automatically follows the vehicle while adjusting the vehicle speed.
You. The distance measuring sensor used in these devices
Known technologies include those using laser radar and millimeter wave
Those using radar are generally known. [0005] Among them, the millimeter wave radar is in a state of rain or fog.
But the target is stable
(Reflectors may be referred to as targets.)
Is expected as an all-weather sensor. In general, automobiles that comply with the Japanese Radio Law
Millimeter waves for the 60-61 GHz or 76-77 GHz frequency band
Area radio waves are to be used. This millimeter wave
The transmitter sends radio waves in the above frequency band from the transmitting antenna
To receive and transmit reflected waves from targets such as vehicles.
The Doppler modulation characteristic of the received wave with respect to the
It detects the distance to the get and the relative speed. The modulation method of the millimeter wave radar is the FMCW method or the FS
Some proposals such as K (Frequency Shift Keying) method
Have been. [0008] Among them, the FSK method is relatively close
Two frequencies are switched and transmitted, and these received waves are transformed.
Distance and relative speed to target using tonality
Etc., and only two oscillation frequencies are required.
This has the advantage of simplifying the circuit configuration of the oscillator and other components.
You. In the FSK system, a receiving antenna is used.
The signal is divided into two parts, left and right, and the signals received by the left and right antennas (left and right
Signal, sometimes called a signal), the power reduction ratio and the left and right reception
Forward target for radar beam from signal phase difference
There is a method to detect the existence angle (azimuth angle) of
The formula is generally called a monopulse system. This monopulse method enables direction detection.
One wide beam without the need for a scanning mechanism
The angle of the target can be detected more and the antenna size
Is smaller in size because antenna is inversely proportional to beam width
It has many advantages, such as being able to. [0011] Such an FSK monopath
Lus-type millimeter-wave radar has various advantages,
There were points to be improved. (1) In this system, as shown in FIG.
The received Doppler modulated signal waveform (reflected wave) is
Technique to perform frequency spectrum analysis by fast Fourier transform)
If you adopt the technique, the speed corresponding to the target of each relative speed
Since multiple peaks appear, there are multiple targets ahead.
If present, the target can be separated,
Two or more targets with exactly the same relative speed
If present, what you see in one spectrum
Therefore, they cannot be separated. (2) In principle, the relative speeds are completely equal.
Two targets simultaneously captured by millimeter-wave radar
The left target with respect to the vehicle traveling direction of both targets.
The right (horizontal) position is the distance from both targets.
The position determined by the ratio of the radiation power (reflection intensity) (where
This position is called the reflection center of gravity position or the reflection center position.
May be detected as having a target)
You. Therefore, for example, as shown in FIG.
The lane on the left and right of the traveling lane (own lane) of the radar vehicle
The vehicles are stopped side by side in the horizontal direction and the millimeter wave
If the vehicle captures both vehicles at the same time,
The strength ratio (center of gravity) is almost at the center between the left and right vehicles
As if there was a stopped vehicle on the own lane
It can be caught. In this case, the stopped vehicle
It is determined that there is a stopped vehicle even though there is no
If no action is taken, a false alarm will be generated.
U. In addition, the millimeter wave radar has the following
An inherent phenomenon occurs. The millimeter wave received by the receiving antenna
The beam from the antenna directly reaches the target,
It is reflected as it is and returns to the receiving antenna.
Besides "wave", it is reflected once on the road surface in either
From the receiving antenna to the receiving antenna.
For this reason, constructing from the phase difference due to the difference in the path length
Weak or multipath interference (multipath reflection characteristics
Sex) is present. And at a certain distance,
Minimal received power that completely cancels out (reverse phase)
Point (referred to as the minimum point at the valley of the received power value)
There is). Such received power is extremely small (minimum
At small distances, it is difficult to catch the target
Become. In this case, there is a preceding vehicle or a stationary object
Is determined to have no target
There is a risk of spilling. The present invention has been made in view of the above points,
This means that even if there are multiple stationary objects in front of
There are multiple objects with the same relative speed, such as both
Case) Separation of these components is ensured.
Millimeter wave that can accurately detect the presence of a stationary object ahead on the line
An object of the present invention is to provide a radar device. Further, the reception power is
Even if the force temporarily decreases, it is not affected by this,
Millimeter-wave radar device that can stably detect targets
To provide. Means for Solving the Problems For example, FSK monopalm
In the millimeter wave radar device in the
Thus, the sum of the left and right antenna reception signals (left and right reception signals)
・ Radar beam from power reduction ratio and phase difference between left and right received signals
The azimuth angle of the target ahead is detected. The azimuth angle is based on the traveling direction of the vehicle relative to the traveling direction of the lane.
Lateral reflection center of gravity of the center and target (lateral reflection position
Are the angles at which the lines connecting The left and right reception signals are in the area of the radar beam width.
The reflected waves from multiple points of the target at
And have the same relative speed as a stationary object.
If there is more than one get,
Reflection of the reflected wave in the transverse direction to the vehicle traveling direction
The center of gravity (lateral reflection center position) of the radiation intensity is determined. Up
The center of gravity of the reflected intensity is the received power due to multipath interference.
Under the influence of force fluctuations, they tend to fluctuate left and right. This
Of various patterns depending on the arrangement of stationary objects in front of the vehicle.
Appear as The fluctuation of the received power described above is indirectly
Appears as a change in the center of gravity of the reflection intensity, and
Fluctuation of the azimuth angle of the stationary object, and thus the front relative to the vehicle traveling direction
Of the horizontal position (lateral position = distance x azimuth angle) of the stationary object
It appears. The present invention has been made based on the above findings.
Basically, the distance from the reflector such as the vehicle ahead, etc.
For vehicles that measure at least one of speed and azimuth
In millimeter wave radar equipment, it is caused by reflection from the road surface.
Power fluctuation or multipath due to multipath interference
Using the horizontal fluctuation of the position of the center of gravity of reflection based on the reflection characteristics
Characterized by having means for estimating the location of the reflective object
I do. Here, the received power change due to multipath interference
Left and right of the center of gravity of reflection based on motion and multipath reflection characteristics
As a form using the direction change, as a representative one,
The azimuth angle variation of the stationary object above
Horizontal position of the stationary object ahead (lateral position = distance x azimuth angle)
These fluctuations include the arrangement and position of stationary objects.
A fixed pattern according to the position has been confirmed. Accordingly
By capturing this pattern,
Estimate your location or separate multiple stationary objects ahead
To determine whether the stationary object is on the own lane.
And become possible. In addition, the multi-beam generated by the reflection from the road surface
Data on minimum point in received power fluctuation due to path interference
The height of the reflected object detected by the radar beam based on the data
Can also be set. Embodiments of the present invention are shown in the drawings.
A description will be given based on the embodiment. FIG. 1 illustrates a system to which the present invention is applied.
As an example of application of millimeter wave radar,
1 shows a distance warning system 1 in which a vehicle 2 moves from a preceding vehicle 3
Millimeter wave radar signal from antenna unit 4
In addition, a system is provided for issuing a warning when approaching.
Reference numerals 5, 10 and 15 constitute the center of the alarm system 1.
Which constitute each means (function) of the arithmetic unit.
You. Here, the millimeter wave radar is an FSK monopulse laser.
It is based on the ordering method. Millimeter wave radar antenna unit
The reflected wave is received by the knit 4 and the inter-vehicle distance to the preceding vehicle 3
The separation / relative speed / azimuth angle measurement 5 is executed. The angular velocity is measured by the gyro sensor 6.
8 and measure the steering angle 9 using the steering sensor 7.
U. The lane of the vehicle position based on the measured angular velocity and steering angle
A decision 10 is made. In this system, the preceding target is the own vehicle.
If you are within the line and approaching from the set inter-vehicle distance
The measured inter-vehicle distance, relative speed, azimuth and lane
Judgment of preceding vehicle 11 and judgment of stationary object ahead of own vehicle
Step 12 is performed. The stationary object determination will be described later in detail. Based on these determinations, an alarm determination algorithm
And the vehicle speed signal and the brake signal 26
Then, an alarm judgment 14 is performed. Warning instruction based on warning judgment
15 and issues an alarm signal 16 to display the driver
At B17, an alarm sound is generated, turned on, and displayed. here
Whether the target is a moving vehicle or a stopped vehicle
Judgment is based on the detected relative speed with the target and the vehicle speed signal.
This can be done by comparing vehicle speeds. FIG. 2 also illustrates a system to which the present invention is applied.
As an application example of the millimeter-wave radar device, AC
C system (follows while keeping a certain distance from the preceding vehicle
Rowing system) 21. This system is also similar to the system of FIG.
Wave radar, gyro sensor 6 and steering sensor 7
Using the antenna unit from the vehicle 2 to the traveling vehicle 3.
A millimeter-wave radar signal is emitted from
Ahead based on the following distance, relative speed, azimuth angle and lane judgment
Car determination 22 and stationary object determination 23 are performed. These decisions
Based on the distance control algorithm 24,
Acceleration / deceleration judgment 2 using the vehicle speed signal and brake signal 26
Perform step 5. Maintain vehicle speed, accelerate and decelerate based on the judgment result
Issue signal 27, throttle control 29, A / T system control
The inter-vehicle distance control 28 comprising the control 30 and the brake control 31
Is going. The system shown in FIG. 1 and FIG.
Information system and ACC system are not necessarily separate systems.
Not only as a system, but also
It is also possible to take a system configuration having the same. FIGS. 3A and 3B show the system described above.
FSK system among millimeter wave radars used in systems
The principle of detecting (measuring) the distance and relative speed by
FIG. As shown in FIGS. 3A and 3B, FSK
In the method, the center frequency f0 (60-61 to 76-7) is used.
7 GHz) with a frequency difference of several hundred kHz
Switching between two frequencies f1 and f2 to generate a transmission signal
You. Received signal reflected back from target 51
Is the Doppler corresponding to the two frequency components f1 and f2
The frequency is shifted by the shift frequency fd1, fd2.
You. At this time, the distance d to the target and the relative velocity v
Is the phase difference φ between the two received signals, that is, (f1 + fd1) −
(F2 + fd2) and one of the Doppler shift frequencies fd
1 and is calculated by the following equation. D = c · φ / 4πΔf v = c · fd1 / 2f1, where c: speed of light, φ: phase, fd1, fd2; Doppler
Fig. 4 shows the circuit block diagram of the millimeter wave radar based on this FSK method.
The lock shows a general configuration. The oscillator 53 is modulated
Upon receiving the modulated signal from the signal generator 52,
The signals of f1 and f2 are generated by switching the signals.
Is transmitted from the transmitting antenna 54. Target
The reflected wave reflected back from the
And received by the server 55. The reception signal is the transmission signal and the mixer 56
Mixing. The mixing signal is synchronized with each modulation signal.
Switched by the operating switch circuit 57, each LPF
(Low-pass filter) 58 and transmitted to phase detector 59
The phase difference φ is detected by the phase detector 59,
From this, the distance d is calculated based on the above equation (1). Actually, the circuit of the millimeter wave radar is shown in FIG.
Not only the analog circuit shown, but also the DSP (digital
Signal by digital circuit using a signal processor
This is realized by using a processing operation. In particular, relative speed
If there are several different preceding vehicles, the mixing signal
Various Doppler shift frequency components corresponding to
[See FIG. 5 (a)]. These are as shown in FIG.
In addition, when frequency spectrum analysis is performed by FFT,
Spectral peak data corresponding to velocity target
Are obtained, and the targets corresponding to the respective relative velocities V are separated.
Can be The real and imaginary parts of each spectrum peak
The phase difference φ can be obtained from the ratio of
The distance to each target can be obtained from equation (1).
You. For stationary objects, the relative speed is closest to the vehicle speed.
As shown in FIG. 5 (b), the position of the Doppler shift frequency
Information can be obtained from the target peak. Next, an object having two receiving antennas on the left and right sides
The pulse method will be described with reference to FIG. The monopulse method uses left and right receiving antennas.
Generate a sum and difference signal of the two received signals, and
Calculate the target angle (azimuth angle) from the signal intensity ratio
Confuse. In other words, two left and right
Receives reflected radio waves from the target (target) with the receiving antenna
I believe. Create an addition / subtraction signal of two received signals,
Based on the signal strength ratio of the addition signal and the subtraction signal,
Use a table of added and subtracted patterns
The target azimuth angle θ or lateral position (vehicle travel
The distance and azimuth angle in the left and right position with respect to the direction
Required. When the horizontal position is X and the azimuth angle is θ
In this case, since θ is small, X = R · sin θ ≒ R · θ.)
Can be requested. Note that the above addition signal and subtraction signal
The ratio of the signal is the center of gravity of the reflection intensity reflected from multiple reflection points
(Reflection center position), this reflection center of gravity and the center of the vehicle
The angle connecting the lines is the azimuth angle. The FSK monopulse radar according to the above method
The target distance, relative speed and azimuth (using
Or lateral position = distance x azimuth).
However, in actual use, each time, due to problems such as S / N ratio,
There is some variation in the measured values. For alarm judgment
To use as data for ACC inter-vehicle distance control,
Smooth continuous curve by smoothing out these variations
It is necessary to For this reason, as shown in FIG.
Filter for target tracking based on luta
Using This tracking filter uses the measured value [distance
Separation d, relative speed v and azimuth angle θ (or lateral position = distance)
Separation x azimuth angle)] and input the data at the next measurement.
Forecast, and update output every time (the most
Smoothing of measured values by deciding
It is intended. This system uses this updated model
And continuous tracking data can be obtained. number
It can be expressed as the following equation. ## EQU2 ## Tracking filter update equation r n + 1 = R n + K (rM n + 1 -RP n + 1 ・ Prediction equation rP n + 1 = R n + (∂rP / ∂t) ・ Δt where r is distance, relative speed, azimuth or lateral position
Is the tracking value, rM is the observed value at each time, and rP is
, K is the filter gain (both are vector tables)
Present). Next, a stationary object including a stopped vehicle is present ahead.
Of stationary objects and warning system
Bell. The alarm system moves even if the vehicle is stationary (stationary object)
If it is determined that the object is on the lane,
When approaching below the distance, the distance between the target and the vehicle
An alarm is issued in consideration of the relative speed v and the distance d. FIG. 8 shows a vehicle stopped forward as a target.
(Stationary object) is in the following modes (1) to (5)
are doing. (1) When one vehicle stops in its own lane
(2) When one vehicle stops in the left lane (3) When one vehicle stops in parallel in the own lane and the left lane
(4) When there are three vehicles and one vehicle is stopped in each lane (5) The vehicle is not on the own lane and one vehicle is stopped on each side of the own lane
In the case of one stop, one vehicle in the right lane and one vehicle in the own lane and one vehicle in the right lane
Is the same as in the above cases (2) and (3).
Therefore, illustration is omitted. In the figure, there is a stopped vehicle in front of the own lane.
When an alarm is required as (1), (3),
This is the case of (4), and (2) and (5) indicate that no alarm is required.
You have to be judged. As described above, the two left and right receiving antennas
In an FSK monopulse radar equipped with
When a reflected radio wave is received from a reflector with the same anti-speed
Is the ratio of the received power received by the left and right antennas (reflection strength
The azimuth angle θ of the center of gravity in degrees is detected. Each stopped vehicle
If the reflection intensity from (each reflection point) is constant,
Radar Cross Section:
(Hereafter referred to as RCS)
To be detected. This principle is illustrated in FIG.
The reflection object may be a plurality of reflection points of one vehicle,
Further, a plurality of vehicles may be used. In this way, the azimuth angle θ or the horizontal position
Position (horizontal position = distance x azimuth angle)
As described above, for example, in the case shown in FIG.
The ratio of the reflection intensity (center of gravity) of the rider is approximately at the center between the left and right vehicles.
It is as if there is a stopped vehicle on the own lane
May be perceived as follows. In the present invention,
This problem is addressed as follows. The transmitted millimeter wave beam has
In addition, there is also a certain width in the vertical direction, some of which
Reaches the road surface and reflects off the road surface before reaching the target
You. Alternatively, the reflected wave reflected from the target
Arrives and is reflected by a receiving antenna after being reflected on one circuit surface.
You. In such a case, the
It is necessary to consider the influence of chipas. In theory, tar
Path of reflected wave directly from get and reflected wave through road surface
Because the lengths are different, we strengthened each other by phase interference
There are places that are weakened. Multiply this phenomenon
This is referred to as received power fluctuation due to path interference. Now, the detection characteristics will be described in an easily understood manner.
Corner riff where RCS is concentrated on one target
Think as a lector. At this time, as shown in FIG.
Height of the center of reflection of the target relative to the ground height h of the antenna
H and the distance R between them determine the road reflection position.
From the geometrical relation, the received power P of the radar is
Is represented. [Equation 3] Where K: constant, Pt: transmission power, G
t: transmission antenna gain, Gr: reception antenna gain,
ρ; road surface reflectance, σ; RCS, λ; wavelength, R AB ; Between AB
Path length, R BCA BCA (ACB) path length, (R BCA =
R ACB = R AC + R CB ), Φ; phase difference due to path length difference. φ
Is related to the above equation as follows. ## EQU4 ## φ = (R AB -R BCA FIG. 10 shows the fixed height h of the receiving antenna of the own vehicle (radar vehicle).
When the reflector height H is changed, the antenna
Reception for the distance connecting the reflectors (distance R in FIG. 9)
Power change characteristics [Received power generated by multipath interference
Of the minimum point (valley point). Here
The generation interval (hereinafter referred to as cycle) of the minimum point of
As the height H of the reflector increases (in other words, as shown in FIG. 9)
The difference between the straight reflection path a and the road reflection path b + c is
(The larger the) the shorter. From now on,
The magnitude of the force is uniquely determined by the target's reflection strength
Rather than the distance,
You can see that FIG. 11 shows a reflector (target) in front of the vehicle.
When there are two stationary objects on the left and right as
Shows the power situation. In this case, the transmission path of the millimeter wave
There are four types. That is, the reflected waves having different path lengths are generated by the left reflector-direct antenna-to-antenna direct left reflector-antenna road surface reflection right reflector-antenna direct right reflector-antenna road surface reflection receiving antenna.
All are combined and input. Multiple stationary objects like this
Even if it includes reflection from the
Power fluctuations (fluctuations in the cycle of the minimum point)
The variation differs depending on the length of the left and right paths. That is, left and right
If the reflector positions are not exactly equal, each interference will occur
The distance you do will be different for left and right. As described above, a plurality of reflectors (tars)
Get) have the same relative speed (here multiple stationary)
Object) If they are lined up on the left and right,
Consider these targets as one, and
The intensity ratio (reflection center of gravity) of the received powers P1 and P2 of the reflector
It is considered as the reflection center position (the detection position in FIG. 11). In this reflection
Center position fluctuates left and right due to multipath reflection characteristics
Tend to occur. FIG. 12 shows test data supporting this.
To change the path length of the left and right reflectors.
By changing the height of the
Shows the left and right fluctuation of the calculated reflection center of gravity (lateral reflection center)
ing. That is, the cord is located at a position separated by a certain distance to the left and right.
Distance when the na-shaped reflector is placed at a height of 5 cm
The change of the lateral reflection center with respect to
Shows the results. Thus, the horizontal direction according to the distance
It can be seen that the reflection center fluctuates greatly from side to side. I
Therefore, when multiple stationary objects are arranged side by side like this,
In the case, the azimuth angle is
The degree and lateral position also fluctuate from side to side. FIGS. 13 to 15 are based on the knowledge of FIG.
Actually set various stop modes of the preceding vehicle, then
The horizontal position measurement value of the
The left and right fluctuation patterns of the measured values are shown for
This is shown in relation to the distance between the two vehicles. However, the distance
Separation data is obtained by passing the measured value through the tracking filter described above.
The value is smoothed. FIG. 13 is a diagram similar to FIG.
FIG. 14 shows the variation characteristics when the vehicle stopped ahead is one lane.
Means that the vehicle stopped ahead is on the left and right of its own lane as shown in (5)
FIG. 15 shows the variation characteristics when there are two units.
Vehicles in front of the vehicle are lined up in the lane and the left and right lanes
This is the variation characteristic when The following can be seen from FIGS. When there is a stopped vehicle on the own lane, the lateral position
Fluctuations occur as the distance decreases (approaches the vehicle stopped ahead).
Tend to converge. If there is a vehicle on the left and right and not on the own lane,
Even if the distance becomes short, the lateral position fluctuation does not converge. Therefore, such lateral position variation characteristics
Consideration has been made to separate stationary objects including multiple stopped vehicles.
And finally, of the stopped vehicles,
It can be determined whether or not there is something above. FIGS. 16 and 17 and FIGS.
Multiple targets caught by radar using position fluctuation characteristics
To separate the get and estimate the stopped vehicle existence pattern
9 shows a flowchart of the algorithm. FIG. 16 shows a first method, in which the above-described track is used.
Filtering filters for left and right and own lane
Forecasts only on lanes where many measurements are observed.
Tigers on the unobserved lane maintaining the racking filter
The locking filter is a method of turning off. First, in step 101, the measured value
(Distance, relative speed, azimuth). target
If a stationary object is observed in the data, step 102
Moves to step 103 to track only distance data
Is done. Next, distance × azimuth = lateral position is calculated (10
4), lateral position tracking for left and right lane and own lane
Run the filter (105). Next, from each horizontal position data value,
In which lane the position data exists, so-called right and left own vehicle
A line hit determination is made (106-109). Next, each car
From the number of hits of the line, the lateral position tracking fill of each lane
It is determined whether the data is updated or turned off (110). This
As a result, target separation is performed, and stationary
Tracking is performed when the vehicle approaches a stationary object at a predetermined distance R0.
(111; this predetermined distance depends on the speed of the vehicle).
As a result), as a result, it is determined that there is a stationary object on the own lane
(112), an alarm is issued (11).
3). FIG. 17 shows the second method, in which the lateral fluctuation (horizontal
3 shows a method of taking the envelope of the variation of the measured value. You
That is, the variation of the lateral position measurement value Y obtained every moment
The return point, that is, the point where (∂Y / ∂t) = 0 is plotted
Take the extreme value of the fluctuation curve, that is, on the envelope
Will be. As shown in FIGS. 13 and 15, on the own lane
If a vehicle is present, the lateral fluctuation will eventually converge. I
Therefore, when the envelope enters the own lane,
It can be determined that there is a vehicle. Specifically, the horizontal position data is set to Y and
First, in step 121, input the differential value (∂Y / ∂t)
Calculate (122) and find a position where this is smaller than a certain value δ.
It is determined as a return point (123). In step 123
Left lane from the data determined as a turning point
Return Y L And turn right lane Y R Search and update (1
24). The width of the turning point ΔY = | YR−YL |
Is calculated (125). Here, the own vehicle is positioned at a certain distance from a stationary object.
When the distance approaches the separation R0, the convergence of ΔY is determined (12).
6, 127). If it is determined that the vehicle has converged,
When it is judged that there is a stationary and it is judged that it does not converge,
It is determined that the vehicle is not on the own lane. If you have your own lane,
Information is issued. FIGS. 18 and 19 show a third method. This hand
The method is based on the distance of the front stationary object at a predetermined interval (each section).
Statistical evaluation of lateral position fluctuation data with respect to separation
In the value result, it is determined whether the stationary object ahead is on the own lane.
For example, as shown in FIG. 14 and FIG.
There are three vehicles in each lane, and one vehicle on the left and right
Effective when executed to distinguish when not on the line
It is a typical usage. First, FIG. 18 shows the horizontal position change of FIGS.
The square of the amount of deviation from the center of motion (= 0)
The value is compared with the cumulative value and the cumulative value every 10m.
You. From this figure, as shown in FIG.
In some cases, the lateral square value is large, especially 90-70.
It turns out that the tendency is remarkable in m. this child
FIG. 19 shows the distance at which the evaluation should be started (forward
Distance between the projectile and the vehicle) and the distance to end the evaluation.
For example, the variance value in this section is evaluated, and there is an evaluation result.
Constructs a flowchart for determining whether a threshold is exceeded
I do. First, a stationary object is detected and is equal to or less than the evaluation start distance.
, The evaluation is started (130 to 131). From time to time
Calculate the variance of horizontal position fluctuations at each end of the evaluation
(132 to 135). If the value is equal to or less than the threshold value, the vehicle stays on the own lane.
It is determined that a stationary object is present
It is determined that there is no stationary object (136 to 137). The evaluation index used for the judgment includes not only the variance but also
For example, the number of hits in each lane can be considered. Here, in the alarm system shown in FIG.
Therefore, it is possible to issue a warning in two stages based on the above judgment results.
it can. That is, first, the stationary object is relatively separated from the front.
Is detected at a certain distance and the lane has not yet been determined.
Generates a first alarm. This alert is low risk and
It is meant to warn Iba of light attention. Next, the own vehicle moves a predetermined distance from a stationary object ahead.
Approaching the separation, the lane is fixed, and the stationary object is the own lane
If determined to be above, decelerate / stop by brake
Or it is necessary to perform an avoidance operation by steering operation.
You. For this, the system issues a second alarm, a collision alarm
Set to strongly inform the driver of the danger. Similarly, the ACC system shown in FIG.
, A two-stage control can be performed. Sandals
First, when a front stationary object is first detected at a relatively large distance
In terms of point, switch to acceleration prohibited or slow deceleration mode.
We change, but do not yet reach the brake operation. But
Approach a stationary object to a predetermined distance,
Is determined and the stationary object is determined to be on the own lane.
Switch to stronger deceleration mode by automatic braking.
You. Or if that alone is not enough
Should give the driver an instruction to avoidance by warning.
And so on. Now, as described above, the circle due to road surface reflection
Depending on the distance to the target due to the influence of chipas characteristics
Therefore, the received power fluctuates greatly. Where a simple reflex
(3) for road surface multipath interference
The minimum received power point could be calculated. Figure 10
The height of the reflector at the time of H is 0.8, 3.0, 5.
In this case, the distance was changed at 5 m. From this figure,
The higher the data height H, the more the received power (interference occurrence point),
And it turns out that the period is short. In general vehicles and the like, depending on the shape, reflection
Due to the distribution of locations, the obvious effect so far is
There is a tendency for reflection to be strong at specific positions, although it does not come out
You. On the other hand, viaducts and guide signs have height reflection positions.
To a certain extent, there is a fairly clear trend
You. The antenna height h of the radar mounted on the vehicle
Is determined, so the ground at the target reflection center position
Multi-path interference generation point and its period depending on high H and distance R
Is determined. This means that stopped vehicles and roadside objects such as viaducts
This is an important property to distinguish between The viaduct is close to the millimeter wave radar
It disappears because it deviates from the vertical beam,
For example, at a distance of about 100m, it enters the upper and lower beams and is detected
Could be done. On the other hand, the relative speed with a stationary object is large
Want to generate a stationary object warning even at high speeds
If a stationary object is detected, it will be a guide sign
Or does not hinder running, such as viaducts and viaducts,
It is an obstacle for traveling, such as a stopped vehicle or a falling object.
It is necessary to determine if it is a target
is there. For example, I want to make an alarm at a distance of 100 m.
Then, for example, the minimum received power point is about 100-150 m
Measurement within the range of
The height H of the reflection center of the front stationary object can be estimated. FIG. 20 shows the distance between the minimum points of the received power.
And the period are detected to estimate the height H of the reflection center, and the estimation result
Shows a flowchart for determining the occurrence of an alarm based on the
You. First, a stationary object at a sufficiently far distance (R> RE)
It is assumed that it is detected (140). Next, the received power P is sometimes changed.
Measurement (141), and the received power is the minimum with respect to the distance.
(R / R) = 0 and the evaluation distance R
Count the number of times the received power reaches the minimum point by E
(142). Reflection center when the distance becomes less than the evaluation distance RE
The height H is estimated (143). This estimate is determined in advance.
From the corresponding data of H and (∂P / ∂R) = 0
(144). Next, the estimated H is compared with a certain threshold value H0.
Compare. If it is determined to be smaller than H0,
It is judged as a stationary object, and if it is judged that it is larger than H0, it is elevated.
It is determined as a non-obstacle such as a bridge (145-147). So
Warning if there is a stationary object in the front lane
Is generated, and no alarm is generated if it is determined that the bridge is a viaduct. According to the embodiment described above: Characteristics of lateral position fluctuation that occurs when multiple stationary objects are captured
Separation of multiple stationary objects and lane judgment
You. 2. Receive power temporarily due to multipath interference
Target is stable regardless of this
2. can be detected From the distance at which the received power is minimized and its period, the reflection center
Estimate the height, non-obstacles such as viaducts and obstacles such as stopped vehicles
By identifying objects, the detection accuracy of stationary objects is increased,
Reducing alarms and erroneous controls to build a highly reliable system
be able to. As described above, according to the present invention, the forward
Ensure that even if there are a number of stationary objects,
Precisely determine whether there is a stationary object ahead on the own lane where the car is traveling
It is an object of the present invention to provide a millimeter wave radar device that can detect the radar. Further, the reception power is
Even if the force temporarily decreases, it is not affected by this,
Target can be detected stably.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a stationary object compatible inter-vehicle distance warning system to which the present invention is applied. FIG. 2 is a schematic configuration diagram of an ACC system for stationary objects to which the present invention is applied. FIG. 3 is a diagram showing a detection principle of the FSK monopulse radar. FIG. 4 is a detection block diagram of an FSK monopulse radar. FIG. 5 is a diagram showing a peak search by FFT. FIG. 6 is an explanatory diagram of the principle of azimuth detection of a monopulse radar. FIG. 7 is a diagram showing a target track by a tracking filter. FIG. 8 is a view showing an arrangement pattern of stopped vehicles. FIG. 9 is a diagram showing a relationship between a radar, a target, and a road surface multipath. FIG. 10 is a diagram showing a relationship between a height of a target reflector and a change in received power. FIG. 11 is an explanatory diagram showing detection positions when there are two reflectors on the left and right. FIG. 12 is an explanatory diagram showing a fluctuation pattern of a left and right center position of a target. FIG. 13 is an actual measurement data diagram showing a relationship between a lateral position, a distance, and a time sequence in the case of one stopped vehicle. FIG. 14 is an actual measurement data diagram showing a relationship between a horizontal position, a distance, and a time sequence in the case of two left and right stopped vehicles. FIG. 15 is an actual measurement data diagram showing a relationship between a lateral position, a distance, and a time sequence in the case of three stopped vehicles. FIG. 16 is a flowchart showing a method for detecting a stationary object, separating the stationary object, and determining the lane of belonging. FIG. 17 is a flowchart showing a method of detecting a lateral position of a stationary object and determining a lane to which the stationary object belongs. FIG. 18 is an explanatory diagram showing square variation data of a lateral position shift amount in FIGS. 13 to 15; FIG. 19 is a flowchart illustrating a method of detecting a lateral position of a stationary object and determining a lane to which the stationary object belongs. FIG. 20 is a flowchart showing a method for estimating the height of a reflection object using the minimum received power estimation algorithm. [Description of Signs] 1... Inter-vehicle distance warning system, 2.
... Antenna unit, 5: Inter-vehicle distance / facing speed / angle measurement, 6 ... Gyro sensor, 7 ... Steering sensor, 8
... angular velocity, 9 ... steering angle, 10 ... lane judgment, 11 ... preceding vehicle judgment, 12 ... stationary object judgment, 13 ... alarm judgment algorithm,
14: warning judgment, 15: warning instruction, 21: ACC system, 22: preceding vehicle detection, 23: stationary object detection, 24: inter-vehicle distance control algorithm, 25: acceleration / deceleration judgment, 26: vehicle speed signal / brake signal, 28 … Inter-vehicle distance control.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshihiro Michiguchi 7-2-1, Omika-cho, Hitachi City, Ibaraki Pref. Hitachi, Ltd. Power and Electricity Research Laboratory (72) Inventor Shiratetsu Jitsu, Hitachinaka, Ibaraki Prefecture No. 2477, Hitachi Car Engineering Co., Ltd. (72) Inventor Kazuo Takano, 2520 Takaba, Hitachinaka City, Ibaraki Pref. Hitachi, Ltd. Automotive Equipment Group (56) References JP-A-5-180933 (JP, A) JP-A-11-45399 (JP, A) JP-A-11-84001 (JP, A) JP-A-11-44476 (JP, A) JP-A-8-124080 (JP, A) JP-A 8-122432 (JP, A) JP-A-5-240952 (JP, A) JP-A-2001-14597 (JP, A) JP-T-2000-502807 (JP, A) International publication 97/25629 (WO, A1) (58) Survey And Field (Int.Cl. 7, DB name) G01S 7/00 - 7/42 G01S 13/00 - 13/95 G08G 1/16

Claims (1)

  1. (57) In the Patent Claims 1. A vehicle dual millimeter wave radar device, means for estimating, based on the measurement data by whether the millimeter wave radar exists stationary forward relative to the vehicle traveling direction Means for estimating whether or not the stationary object is on its own lane by using the left-right direction fluctuation of the position of the center of gravity of reflection based on the multipath reflection characteristic generated by reflection from the road surface. Radar equipment. 2. The vehicle millimeter wave radar device according to claim 1, wherein
    The millimeter wave radar device according to claim 1, wherein the device is a monopulse system . 3. A vehicle dual millimeter wave radar device, means for estimating, based on the measurement data by whether the millimeter wave radar exists stationary forward relative to the vehicle traveling direction, multipath caused by reflection of the road surface A millimeter-wave radar device comprising: means for separating and capturing a plurality of front stationary objects by using a left-right variation of a reflection center of gravity position based on reflection characteristics. 4. The vehicle millimeter wave radar device according to claim 1, wherein
    4. The millimeter wave radar device according to claim 3, wherein the device is a monopulse system . 5. A vehicular millimeter wave radar device for measuring at least one of a distance, a relative speed, and an azimuth angle with respect to a reflector such as a preceding vehicle, wherein a minimum in received power fluctuation due to multipath interference caused by reflection from a road surface. A millimeter wave radar device comprising: means for estimating the height of the reflection object based on data on points. 6. A means for judging that the reflective object is a stationary object, and when it is determined that the estimated height is equal to or more than a predetermined value, the reflective object is a stationary object that does not become an obstacle for vehicle traveling. Item 6. A millimeter wave radar device according to item 5 .
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US7570197B2 (en) 2001-05-30 2009-08-04 Hitachi, Ltd. Radar device
JP4043276B2 (en) * 2002-04-24 2008-02-06 株式会社日立カーエンジニアリング Radar equipment
JP2006275828A (en) * 2005-03-30 2006-10-12 Fujitsu Ltd Radar system
JP2007286033A (en) * 2006-03-23 2007-11-01 Omron Corp Radio detector and method
US7623061B2 (en) * 2006-11-15 2009-11-24 Autoliv Asp Method and apparatus for discriminating with respect to low elevation target objects
JP2008249405A (en) * 2007-03-29 2008-10-16 Mitsubishi Electric Corp Method and device for object identification
JP5059717B2 (en) * 2008-09-04 2012-10-31 日立オートモティブシステムズ株式会社 Monopulse radar device
JP2010237087A (en) * 2009-03-31 2010-10-21 Hitachi Automotive Systems Ltd Radar apparatus and method for measuring radio wave arrival direction using the same
JP4905512B2 (en) 2009-07-09 2012-03-28 株式会社デンソー Target information estimation device
DE112009005399B4 (en) * 2009-11-27 2014-08-28 Toyota Jidosha Kabushiki Kaisha radar device
JP2011122876A (en) * 2009-12-09 2011-06-23 Toyota Central R&D Labs Inc Obstacle detector
JP5256223B2 (en) * 2010-01-27 2013-08-07 富士通テン株式会社 Radar system and direction detection method
JP5697904B2 (en) * 2010-06-16 2015-04-08 株式会社豊田中央研究所 Radar apparatus and detection method
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JP6142516B2 (en) * 2012-12-07 2017-06-07 日本電気株式会社 Altitude measuring device and altitude measuring method
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US9989630B2 (en) * 2015-05-13 2018-06-05 Infineon Technologies Ag Structured-light based multipath cancellation in ToF imaging

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