JPH0766057B2 - Leading vehicle detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a preceding vehicle detection device that transmits an electromagnetic wave in front of a host vehicle and tracks a preceding vehicle while receiving a reflected wave of the electromagnetic wave reflected by a preceding vehicle.

[Technical Background of the Invention and Problems Thereof] An apparatus for controlling a vehicle speed or tracking a preceding vehicle by mounting a radar device on a vehicle and detecting a preceding vehicle or an obstacle existing in front of the vehicle is known. Various types are being developed.
(For example, Japanese Patent Publication 51-7892). By the way, conventionally, in such an apparatus for mounting a radar device to track a preceding vehicle, the preceding vehicle detected and tracked by the radar device travels on the same traveling lane as the own vehicle's traveling lane. Since it is not possible to determine whether or not the vehicle is in the same lane as the host vehicle, it cannot be detected even if the vehicle has moved to another lane on the way, and the preceding vehicle has moved to another lane. Will continue to be tracked. As a result, for example, even if another preceding vehicle having a slow speed is traveling ahead in the traveling lane of the own vehicle after the preceding vehicle moves to another preceding lane, the other preceding vehicle is ignored. For,
There is a problem that a true preceding vehicle traveling on the traveling lane of the host vehicle cannot be accurately detected.

[Object of the Invention] The present invention has been made in view of the above, and an object of the present invention is to provide a preceding vehicle detection device that always accurately detects a preceding vehicle existing in the traveling lane of the own vehicle. To provide.

[Summary of the Invention] In order to achieve the above object, according to the present invention, as shown in FIG. 1, a transmitting means 2 for transmitting an electromagnetic wave in at least two different horizontal directions including a front direction of the own vehicle 1 and a front direction of the own vehicle. If, receives a reflected wave from the reflector 3 _l to 3 _n of the electromagnetic wave the transmitting means 2 transmits the direction indicating the direction of the reflector 3 _l to 3 _n with respect to the vehicle 1 from the reception direction of the reflected wave Directional distance measuring means for outputting a signal and calculating the distance from the vehicle 1 to the reflectors 3 _{l to} 3 _n based on the propagation delay time from the electromagnetic wave transmission time to the reflected wave reception time and outputting a distance signal. Four
And the respective distances at the time of the previous measurement and the current measurement based on the distance signal from the directional distance measuring means 4 and the required times for obtaining the distances, the own vehicle 1 and the reflectors 3 _l to 3 _{l If} the speed difference with _n is calculated and the speed difference is within a preset required value, the tracking preceding vehicle setting means 5 for setting the reflector as the tracking preceding vehicle, and the tracking preceding vehicle setting means 5 If a signal indicating that the reflectors 3 _{l to} 3 _n are detected in the second or third direction is detected when the set preceding vehicle cannot detect in the first direction, the direction distance is detected. If the distance from the own vehicle based on the distance signal from the detecting means to the reflectors 3 _{l to} 3 _n is substantially the same as the distance from the own vehicle that is no longer detected in the first direction to the tracking preceding vehicle, determines that the reflector 3 _l to 3 _n of the same vehicle and the tracking preceding vehicle, new To re-set as the tracking the preceding vehicle, the first tracking the preceding vehicle resetting means for outputting a reset signal to the tracking preceding vehicle setting means 5 6
Then, it is detected by the signal from the first tracking preceding vehicle resetting means 6 that there is no tracking preceding vehicle in front of the vehicle, and the direction signal from the direction distance setting means 4 indicates that the vehicle is in the front direction. When another preceding vehicle is detected, it is determined that another preceding vehicle is approaching the host vehicle based on the distance signal of the previous measurement and the distance signal of the present measurement from the direction distance measuring means 4. The second tracking preceding vehicle resetting means 7 for outputting a resetting signal to the tracking preceding vehicle setting means 5 so as to reset another preceding vehicle as a tracking preceding vehicle. .

Embodiments of the Invention Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, in which a combination of a radar device 31 as a transmitting means and a direction distance measuring means and a preceding vehicle distance determining means 37, a tracking preceding vehicle setting means, a first tracking preceding means. The processing unit 35 as a vehicle resetting unit and a second tracking preceding vehicle resetting unit, a vehicle speed sensor 33, and an acceleration / deceleration mechanism 41 are provided. And the preceding vehicle distance determining means 37
Is the distance signal lR in the right direction, the distance signal lC in the front direction, and the distance signal lL in the left direction, which are supplied from the radar device 31, are received, and the preceding vehicle calculated while tracking the target preceding vehicle according to the processing described later The distance signal 1 and the right flag R, the front flag C, or the left flag L information indicating the traveling laser beam capturing the preceding vehicle is supplied to the arithmetic processing means 35, and the arithmetic processing means 35 supplies the vehicle speed from the vehicle speed sensor 33. Acceleration / deceleration mechanism 41 based on signal v and distance signal 1 from preceding vehicle distance determination means 37
Is controlled to control the acceleration / deceleration of the host vehicle.

The radar device 31 is roughly divided into a light output unit 43, a light receiving unit 45, and a control unit 47. The light output unit 43 includes a light output device 51 having an optical axis in the front direction of the vehicle body and angles θ _R and θ _L (θ _R = θ) in the right and left directions with respect to the optical axis in the front direction of the vehicle body.
_It comprises, for example, three light output devices 49 and 53 having optical axes shifted by _{L 1} ). Each optical output device 49,51,53 has a laser diode 55,57,59 and a lens 61,63,65, respectively, the laser output by the laser diode 55,57,59 lens 61,63,65 Spread angle θ _TR , θ _TC , θ _TL (θ _TR
= Θ _TC = θ _TL ), strength L _TR , L _TC , L _TL (L _TR = L _TC = L _TL )
It radiates at. Therefore, as a laser,
The light is radiated in the front-rear direction of the vehicle body and symmetrically with respect to the light axis. The light receiving section 45 captures the light reflected by the reflector of the laser emitted from the light output section 43 in this way, and includes a light receiving element 67 and a condenser lens 69 that forms a focus on the light receiving surface of the light receiving element 67. It is a structure having. The control unit 47 controls emission and reception of laser light to obtain the distance and direction to the reflector, and has a configuration including a pulse modulator 71, an amplifier 73, a comparator 75, and an arithmetic circuit 77. The pulse modulator 71 has a pulse width of about 100 nsec and an oscillation frequency of KHz.
Then, the pulse modulation signal is sequentially output to the laser diodes 55, 57, 59 to drive and control them, and the light emission signal is output to the arithmetic circuit 77 in synchronization with the output of the pulse modulation signal. The amplifier 73 and the comparator 75 amplify the received light signal photoelectrically converted with respect to the light received by the light receiving element 67, and output the signal exceeding the set level among the received light signals to the optical output unit 43.
The signal is extracted as a reflection signal from the reflector of the laser radiated from and output to the arithmetic circuit 77. The arithmetic circuit 77 is
Since the direction and the distance in which the reflector is present are obtained based on the input time difference between the light emission signal and the reflection signal, the distance calculation is performed by the following equation using the input time difference.

Distance: l = m · T / 2 where m is the speed of light (3 × 10 ⁸ m / sec) and T is the input time difference.

FIG. 3 is a flowchart showing the processing performed by the preceding vehicle distance determining means 37 and the arithmetic processing means 35.

Before explaining each processing flow shown in FIG. 3, the principle or concept of the processing flow of FIG. 3 will be described first with reference to FIGS. 4 and 5.

The process shown in the flowchart of FIG. 3 is suitable only for a true preceding vehicle even when a preceding vehicle traveling in the traveling lane of the host vehicle travels on a curved road, for example, based on the distance signals in each direction detected by the radar device 31. This is a process for tracking while accurately detecting, and by detecting the preceding vehicle appropriately in this way, for example, erroneously detecting another vehicle traveling in another lane on a curved road as a preceding vehicle. This is used to prevent the above, detect only the inter-vehicle distance to the true preceding vehicle, and thereby maintain an appropriate safe inter-vehicle distance.

More specifically, the azimuth distance signal to the preceding vehicle detected by the center, right, and left laser beams from the light output devices 51, 49, 53 in the front, right, and left directions of the host vehicle, that is, the front distance value lC _i , The right distance value lR _i , the left distance value lL _i (i indicates the passage of time), and the laser beam used to detect the preceding vehicle being tracked based on changes in these distances is always known. Therefore, the center flag C is set to "1" when the preceding vehicle is detected by the central laser beam, and the right flag R is set to "1" when the preceding vehicle is detected by the right laser beam, When the left laser beam is detected, by controlling the flag so that the left flag L is set to "1", it is possible to clearly understand by the flag display which laser beam always captures the preceding vehicle. Tracking precedence It is detected without mistake even in the example curved road or the like.

The addition, for example a preceding vehicle which is traveling on a straight road at time t _i-1 when the central laser beam had tracked captured by the front distance lC _i-1, enters the example right curve road at the next time ti, If the adjacent right laser beam detects the preceding vehicle at the right distance lR _i just before the preceding vehicle goes out of the detection range of the central laser beam and cannot be detected by the central laser beam, this preceding vehicle is simply continuous. manner since only the right curve, so the right distance lR _i detected by the right laser beam immediately before the time t _i-1 front distance lC _i-1 central laser beam was detected at the time ti It does not mean that there is a large change in the distance, and it is considered that the change is almost the same or small even if there is a change and is within the predetermined distance α of a relatively small value. Therefore, the front distance lC _i-1
And by comparing the right distance lR _i, if the difference between the distance or both distances same have been determined to be within the predetermined distance α is now right laser beams at the detected preceding vehicle is now It is possible to identify the preceding vehicle that was being tracked by the central laser beam. That is, even if the preceding vehicle that has been tracking in this way enters a curved road and its position with respect to the preceding vehicle changes, and even if the detected laser beam changes, the distance detected from each laser beam, that is, the change in inter-vehicle distance Therefore, the preceding vehicle that has been tracked up to now can be surely identified, and the preceding vehicle is not lost or another vehicle is not mistakenly identified as the preceding vehicle.

In addition, FIG. 4 shows that a preceding vehicle indicated by a diagonally shaded rectangle and a rectangular own vehicle not shaded pass a straight curved road to a straight curved road and then a left curved road to a straight curved road. The relationship between the laser beam and the preceding vehicle and the change in which laser beam the preceding vehicle enters and is detected when traveling on the route returning to
It is shown according to t12. FIG. 5 shows the azimuth distance signal for the preceding vehicle detected by the radar device 31 in this series of changes, that is, the front distance value lC and the right distance value.
1R, the leftward distance value lL, and the set contents of the center flag C, the right flag R, and the left flag L at that time, that is, the relationship of "1" or "0" is shown with respect to the elapsed time t1 to t12. . The processing flow shown in FIG. 3 and outlined above is tracked by proceduralizing the relationship between the preceding vehicle and each laser beam and the relationship with the azimuth distance signal, which can be seen from FIGS. 4 and 5. It is the one that is surely detected so as not to lose sight of the preceding vehicle.

As can be seen from FIG. 4 and FIG. 5, when traveling on a straight road, the preceding vehicle enters the detection range of the central laser beam and is detected by the beam, and the front distance value lC indicates the distance to the preceding vehicle. The central flag C is "1". When traveling on the right curve, the preceding vehicle enters the detection range of the right laser beam and is detected by the beam, the right distance value lR indicates the distance to the preceding vehicle, and the right flag R is "1". ing. When traveling on the left curve, the preceding vehicle enters the detection range of the left laser beam and is detected by the beam, the leftward distance value lL represents the distance to the preceding vehicle, and the left flag L is "1". ing. The azimuth distance signal lC, lR, lL is maintained substantially constant value determined by the vehicle speed for a distance to the preceding vehicle being tracked, but for example, time t ₂ -t ₃
When the left laser beam detects the roadside reflector while traveling on a curved road, the leftward distance lL changes drastically according to the position of the reflector as shown in the figure, and at time t ₅ -t ₆
Or t ₈ right distance when the right laser beam as shown between -t ₁₀ detects a vehicle traveling in other driving lane lR
Is not constant and is changing at a considerable rate.

Next, the processing flow of FIG. 3 will be described with reference to FIGS. 4 and 5. The processing flow of FIG. 3 is started and executed every fixed time, for example, every several 100 mm seconds by interruption processing in, for example, a microcomputer which constitutes the preceding vehicle distance determining means 37, and is executed every time this is started, that is, the time. At t = i, first of all, to the right of the vehicle of the radar device 31,
Front, left, right from the light output device 49, 51, 53, center,
The azimuth distance signal to the preceding vehicle detected by the left laser beam, that is, the right distance value lR _i front distance value lC and the left distance value lL _i are sequentially input (step 110). At the next step 120, at the immediately preceding start, that is, at time t = _i-1
Reads the detected stored right distance value lR _i-1 front distance value lC _i-1, the left distance value lL _i-1 from the memory in.

Thus the right distance value lR _i at the current time t = i in step 110, the front distance value lC, after entering the left distance value lL _i, the process flow, for the preceding vehicle that was detected in the middle laser beam First processing flow (steps 130 to 1)
39), the second processing flow for the preceding vehicle detected by the right laser beam (steps 140 to 146), and the third processing flow for the preceding vehicle detected by the left laser beam (steps 150 to 156) And a fourth processing flow for setting an inter-vehicle distance li between the target preceding vehicle to be tracked (steps 160 to 18).
1) and a fifth processing flow for determining whether or not there is another preceding vehicle in the front direction of the own vehicle with the central laser beam when the target preceding vehicle is detected and tracked by the right or left laser beam (Step 200-250) and as a result of the first to third processing, there is no target preceding vehicle, and a new target preceding vehicle is newly set.
The processing flow (steps 300 to 330), a constant speed travels when the target preceding vehicle is absent, and when the target preceding vehicle exists, acceleration / deceleration is performed according to the distance li to the target preceding vehicle. An eighth processing flow (step 380, 370) in which the right distance value lR _i , the front distance value lC _i , and the left distance value lL _i are stored in the memory to advance to the next operation cycle. 39
It is roughly divided into 0). Then, the processing as the tracking preceding vehicle setting means is executed by the first processing flow and the sixth processing flow, and the first and second processing is executed by the second processing flow and the third processing flow. The processing as the tracking preceding vehicle resetting means is executed.

First, in the first processing flow shown in steps 130-139, the preceding vehicle is controlled by the central laser beam by checking whether the central flag C is "1" at the time t _i-1 one step before in step 130. Identify whether or not it was detected in. When the central flag C is "1", the preceding vehicle was detected by the central laser beam, which is the time t ₀ -t ₁ , t ₄ -t ₇ , in FIGS. 4 and 5. t ₁₀ -t ₁₁
In this state, the preceding vehicle may turn to the right when it encounters a right-curved road, such as the change at time t ₁ → t _2, or to the left, such as the change at time t ₈ . Or, it may be traveling on a straight road without any change. Therefore, the state in which the preceding vehicle has advanced is detected based on the detected and read out direction distance signals, and the flag R, L or C indicating the detected direction is set, and the preceding vehicle is detected. This indicates that the laser beam is detected in the direction indicated by the set flag, so that the preceding vehicle can always be reliably caught.

That is, in steps 131 to 133, the preceding vehicle is at time t ₁
→ To check whether or not there is a right curve like the change at t ₂ , first calculate the distance difference between the right distance value lR _i and the front distance value lC _i, and this distance difference is the predetermined distance. Check if it is within α. The predetermined distance α is a relatively small value as described above, and more specifically, the predetermined distance α is a time interval at which the process flow of FIG. A value with a slight margin for the change in the inter-vehicle distance may be sufficient, and the variation in the inter-vehicle distance when considering the ranging accuracy of the radar device 31 ± 1 m and the vehicle speed is within 1 m, so a margin is provided for this. Predetermined distance α
= 4m should be selected.

As a result of the check in this step 131, the fact that the distance difference is within the predetermined distance α indicates that the preceding vehicle has made a right curve and is newly detected by the right laser beam, and the right direction distance value lR _i
It has been identified that the preceding vehicle with is the same as the preceding vehicle that has been detected by the central laser beam up to now and had the frontal distance value lC _i−1 , and therefore the procedure proceeds to step 132. In step 132, the distance difference between the front distance value lC _i and the front distance value lC _i-1 is calculated, and it is checked whether or not this distance difference is within the predetermined distance α. Leading vehicle is time ti
In the case where the vehicle cannot be detected by the center laser beam due to a complete right curve at (that is, when the preceding vehicle cannot detect it within the predetermined distance change range), the front distance value
Since lC _i is infinite, frontal distance value lC _i and frontal distance value lC
The distance difference from _i-1 becomes larger than the predetermined distance α, and it is determined that the preceding vehicle is completely within the detection range of the right laser beam and is detected by the beam. Therefore, in the next step 133, the central flag C = 0, the right flag R = 1, and the left flag L.
= 0 and proceed to step 160.

Further, when the difference in distance between the rightward distance value lR _i and the frontal distance value lC _i-1 is not within the predetermined distance α in step 131, and in step 132 the distance between the frontal distance value lC _i and the frontal distance value lC _i-1. If the difference is within a predetermined distance α is the preceding vehicle instead of the right curve, since the preceding vehicle may or directly traveling straight when you left curve is considered as at time t _8, first in step 134 to In order to check whether or not the curve is a left curve at 136, _first , the distance difference between the left distance value lL _i and the front distance value lC _i-1 is calculated, and this distance difference is within the predetermined distance α. Check whether or not.

The result of the check in step 134, said distance difference is within a predetermined distance α is to the preceding vehicle has left curve as at time t _8, with a leftward distance value lL _i is newly detected by the left laser beam It has been identified that the preceding vehicle is the same preceding vehicle that has been detected by the central laser beam up to now and had the frontal distance value lC _i−1 , and therefore step 135 is proceeded to. In this step 135,
Similar to step 132, the front distance value lC _i and the front distance value lC
The distance difference from _i-1 is calculated, and it is checked whether or not this distance difference is within the predetermined distance α. When the preceding vehicle completely curves to the left at time ti and is not detected by the central laser beam, the front distance value lC _i is infinite, so the front distance value lC _i
And the frontal distance value lC _i-1 are greater than the predetermined distance α, and it is determined that the preceding vehicle is completely within the laser beam detection range and is detected by the beam. Therefore, in the next step 136, the central flag C = 0 and the right flag R =
0, left flag L = 1 is set, and the process proceeds to step 160.

Further, when the distance difference between the leftward distance value lL _i and the frontal distance value lC _i-1 is not within the predetermined distance α in step 134 and the distance between the frontal distance value lC _i and the frontal distance value lC _{i-1 in} step 135. If the difference is within the predetermined distance α, the preceding vehicle may not have made a left curve, but the preceding vehicle may go straight ahead. Therefore, the routine proceeds to step 137 and the front distance value lC _i
And a frontal distance value lC _i-1 are calculated, and it is checked whether or not this distance difference is within a predetermined distance α. The fact that this distance difference is within the predetermined distance α means that it is determined that the preceding vehicle is detected by the central laser beam at time ti as well as at time ti _-1 , so the routine proceeds to step 138. The center flag C = 1, the right flag R = 0, and the left flag L = 0 are set to the same values as before, and the process proceeds to step 160.

Also, in step 137, the frontal distance value lC _i and the frontal distance value are
a distance difference between the lC _i-1 is not within the predetermined distance α is, for example a preceding vehicle as at time t ₁₂ how the laser beam is also moved to the other traffic lane or the like can not be detected by determination that the preceding vehicle has disappeared Therefore, the routine proceeds to step 139, where the central flag C = 0, the right flag R = 0 and the left flag L = 0 are set to indicate that there is no preceding vehicle, and step 160
Proceed to.

Furthermore, as a result of checking the central flag C in step 130, when the central flag C = 0, step 140
Then, it is checked whether the right flag R is "1". Although if the right flag R is "1" is not the preceding vehicle has been detected only in the right laser beam has a right curve, which is the time t ₂ -t in FIG. 4 and FIG. 5
₃ , t ₁₁ -t _12, in which the preceding vehicle was turning right as at time t ₄ , returning straight, or not changing and continuing right turning. There is.

Therefore, when the right flag R = 1, the steps 141-1
At 43, in order to check whether or not the preceding vehicle is curving right as at time t ₄ and returns to straight traveling, first the front distance value lC _i and the right distance value lR _i-1 Is calculated, and it is checked whether or not this distance difference is within a predetermined distance α. As a result of the check in this step 141, the fact that the distance difference is within the predetermined distance α indicates that the preceding vehicle has returned to the straight running from the right curve, and thus the preceding vehicle having the frontal distance value lC _i newly detected by the central laser beam. Has been detected by the right laser beam until now, and the right distance value lR _i-1
It has been identified that the vehicle is the same as the preceding vehicle that had the following. Therefore, the routine proceeds to step 142. In this step 142, the rightward distance value lR _i and the rightward distance value lR _i
The distance difference from _i-1 is calculated, and it is checked whether or not this distance difference is within the predetermined distance α. If the preceding vehicle completely goes straight at time ti and cannot be detected by the right laser beam, the right distance value lR _i is infinite, so the right distance value lR _i and the right distance value lR _i-1 The distance difference between the vehicle and the vehicle becomes larger than the predetermined distance α, and it is determined that the preceding vehicle is completely within the detection range of the central laser beam and is detected by the beam. Therefore, in the next step 143, the central flag C = 1,
The right flag R = 0 and the left flag L = 0 are set, and step 16
Go to 0.

If the distance difference between the frontal distance value lC _i and the rightward distance value lR _i-1 is not within the predetermined distance α in step 141, and in step 142 the rightward distance value lR _i and the rightward distance value lR _i
If the distance difference from _i-1 is within the predetermined distance α, it is considered that the preceding vehicle may not be returning to the straight running from the right curve but is continuing the right curve. A distance difference between the direction distance value lR _i and the right direction distance value lR _i-1 is calculated, and it is checked whether or not the distance difference is within a predetermined distance α. If this distance difference is within the predetermined distance α, it means that the time ti
Since it is determined that the preceding vehicle is being emitted by the right laser beam at the same time t _i-1 , the process proceeds to step 145 and the central flag C = 0, the right flag R = 1, and the left flag L. = 0 and set the same as before, and the process proceeds to step 160.

If the distance difference between the rightward distance value lR _i and the rightward distance value lR _i-1 is not within the predetermined distance α in step 144,
Since it can be determined that the preceding vehicle has moved to another traveling lane where any laser beam cannot be detected and the preceding vehicle has disappeared, the routine proceeds to step 146, where the central flag C = 0 and the right flag R.
= 0, the left flag L = 0 is set to indicate that there is no preceding vehicle, and the routine proceeds to step 160.

Further, as a result of checking the right flag R in step 140, if the right flag R = 0, the process proceeds to step 150 to check whether the left flag L is "1".
Although if left flag L is "1", which is not the preceding vehicle has been detected only in the left laser beam has a left curve, which time t ₈ -t ₉ in FIG. 4 and FIG. 5 In this state, the preceding vehicle is at time t ₉
There is a case where the vehicle is left-turning as in the case of returning to straight running, or there is a case where the vehicle keeps the left-curve without changing.

Therefore, when the left flag L = 1, first, steps 151 to 1 are executed.
At 53, in order to check whether or not the preceding vehicle has left-curved as at time t ₉ to return to straight traveling, first the frontal distance value lC _i and the leftward distance value lL _i-1 Is calculated, and it is checked whether or not this distance difference is within a predetermined distance α. As a result of the check in this step 151, the fact that the distance difference is within the predetermined distance α indicates that the preceding vehicle has returned to straight traveling from the left curve, and thus the preceding vehicle having the front distance value lC _i newly detected by the central laser beam. Has been detected by the left laser beam until now, and the distance value in the left direction lL _i-1
It is identified that the vehicle is the same as the preceding vehicle that had the following. Therefore, the process proceeds to step 152. In this step 152, the leftward distance value lL _i and the leftward distance value lL
The distance difference from _i-1 is calculated, and it is checked whether or not this distance difference is within the predetermined distance α. When the preceding vehicle has completely returned straight ahead at time ti and cannot be detected by the left laser beam, the leftward distance value lL _i is infinite, so the leftward distance value lL _i and the leftward distance value lL _i-1 The distance difference between the vehicle and the vehicle becomes larger than the predetermined distance α, and it is determined that the preceding vehicle is completely within the detection range of the central laser beam and is detected by the beam. Therefore, in the next step 153, the central flag C = 1,
The right flag R = 0 and the left flag L = 0 are set, and step 16
Go to 0.

Further, the left distance value lL _i and left distance value when the distance difference between the front distance value lC _i and left distance value lL _i-1 is not within the predetermined distance α and step 152 in step 151 lL
_If the distance difference from _i-1 is within the predetermined distance α, it is possible that the preceding vehicle has not continued to go straight from the left curve but is continuing the left curve, so proceed to step 154 and turn left. The distance difference between the direction distance value lL _i and the left direction distance value lL _i-1 is calculated, and it is checked whether or not this distance difference is within the predetermined distance α. If this distance difference is within the predetermined distance α, it means that the time ti
Since it is determined that the preceding vehicle is being irradiated with the left laser beam at the time t _i−1 , the process proceeds to step 155 and the central flag C = 0, the right flag R = 0, and the left flag L. = 1 and the same as before, and the process proceeds to step 160.

If the distance difference between the leftward distance value lL _i and the leftward distance value lL _i-1 is not within the predetermined distance α in step 154,
Since it can be determined that the preceding vehicle has moved to another traveling lane that cannot be detected by any laser beam and the preceding vehicle has disappeared, the routine proceeds to step 156, where the center flag C = 0 and the right flag R
= 0, the left flag L = 0 is set to indicate that there is no preceding vehicle, and the routine proceeds to step 160.

As described above, the target preceding vehicle is surely detected by the first, second, and third processing flows, and the laser beam being detected is detected by the center flag C, the right flag R, or the left flag L.
After tracking the preceding vehicle while marking with, the procedure proceeds to the fourth processing flow to set the inter-vehicle distance li to the target preceding vehicle.

That is, in steps 160, 170, 180, the above 1-
It is checked which flag C, R or L is set in the third processing flow, and the azimuth distance value corresponding to the set flag, that is, the front distance value lC _i , the rightward distance value lR _i or the leftward distance value. lL _i is set as the inter-vehicle distance li (steps 161, 171, 181). Here, if the flag C = 1 and the target preceding vehicle is set by the central laser beam, the seventh
If the target preceding vehicle is absent because none of the flags is set and the target preceding vehicle is absent, the target preceding vehicle is a right or left laser with flag R = 1 or flag L = 1. If it is detected by the beam, the process proceeds to the next fifth processing flow, and while tracking the target preceding vehicle with the right or left laser beam, another preceding vehicle is newly added within the range detected by the front laser beam. Detects whether a car is present.

First, in step 200, it is determined whether the frontal distance value lC _i is the distance to the preceding vehicle or the distance to the roadside object from the temporal change in the frontal distance detected so far, for example, in Japanese Patent Application No. 58- The determination is made using the method disclosed in No. 229042. If it is determined that it is the distance to the preceding vehicle,
In step 210, the relative speed Δv with respect to the preceding vehicle is calculated from the inter-vehicle distances lC _i-9 , lC _i-8 , ..., LC _i-1 , lC _i with the preceding vehicle detected by the front laser beam. then,
It is checked whether or not the calculated relative speed Δv is negative (step 220). If the calculated relative speed Δv is negative, it means that the host vehicle is approaching the preceding vehicle. Distance from the preceding vehicle detected by the front laser beam
It is checked whether lC _i is shorter than a predetermined inter-vehicle distance lTH (step 230). If it is short, it is determined that the preceding vehicle detected by the front laser beam has a higher risk to the own vehicle than the target preceding vehicle that has been tracked until now, so the central flag C = 1, right The flag R = 0 and the left flag L = 0 are set, and the target preceding vehicle to be tracked is changed to the preceding vehicle detected by the front laser beam, and the front distance value lC _i detected by the front laser beam is set as the inter-vehicle distance l _i . (Step 240,25
0), and proceeds to the seventh processing flow. Further, if the preceding vehicle cannot be detected in the check in step 200, if the relative speed Δv is positive in the check in step 220, that is, the distance from the preceding vehicle is increasing, the front laser beam is detected in the check in step 230. When the distance lC _i to the preceding vehicle is larger than the predetermined inter-vehicle distance lTH, it is considered that there is no preceding vehicle having a high degree of danger, so that the tracking preceding vehicle is not changed and the process proceeds to the seventh processing flow.

When the preceding vehicle is detected by the front laser beam and the relative speed Δv is calculated in steps 200 and 210, the relative speed Δv is negative and the distance lC _i to the preceding vehicle is shorter than the predetermined inter-vehicle distance lTH. In addition, it is judged that the preceding vehicle detected by the front laser beam is more dangerous to the own vehicle than the target preceding vehicle that has been tracked until now, but it is not limited to this criterion. , The inter-vehicle distance lTH is a function of the relative speed Δv (for example, lTH = l _i + Δ
v, where k is a positive constant), and whether or not lC _i <lTH is satisfied may be used as a criterion.

If the target preceding vehicle cannot be detected in any of the first to third processing flows and no flag is set, the process proceeds from step 4 to step 300 in the sixth processing flow to check the vehicle-to-vehicle distance. The distance l _i is set to nothing, and in the next step 310, the frontal distance value lC _i is the distance from the preceding vehicle or the roadside object from the temporal change of the frontal distance detected so far by the same processing as in step 200. It is determined whether it is a distance. When the distance is the distance to the preceding vehicle, the preceding vehicle is set as the target preceding vehicle to be tracked, the front flag C = 1, the right flag R = 0, and the left flag L = 0 are set and detected by the front laser beam. The front distance value lC _i is set to the inter-vehicle distance l _i and the process proceeds to step 340 of the seventh processing flow.

In step 340 of the seventh processing flow, it is checked whether or not the front flag C = 1. In the case of flag C = 1, the front laser beam is capturing and tracking the preceding vehicle. In this case, the inter-vehicle distance to the preceding vehicle is
Acceleration / deceleration α is calculated according to l _i , and this acceleration / deceleration α is −α
It is determined and output within the range of ₀ <α <+ α ₀ (for example, α ₀ = 3 km / sec) (step 360).

If the flag C is not 1, the right or left laser beam other than the front laser beam is capturing and tracking the preceding vehicle. In this case, the inter-vehicle distance to the preceding vehicle is
Acceleration / deceleration α in which the acceleration is limited to a predetermined amount or less is determined according to l _i within the range of −α ₀ <α <+ αth (for example, αth = 1 km / h / sec) and output (step 350).

When the preceding vehicle cannot be detected at step 310, the routine proceeds to step 370, where a constant speed traveling control command is output to make the own vehicle travel at a constant speed.

In the eighth processing flow, the rightward distance value lR _i , the frontal distance value lC _i , and the leftward distance value lL input in step 110 are input.
_It is stored in the _i memory (step 380), and then the period of the interrupt time is incremented by 1 and this processing is ended (step 390).

In the above embodiment, the case where the number of laser beams is three has been described, but other number of beams, for example, 2, 4,
It is possible to select 5, ..., etc., and it is possible to estimate the preceding vehicle detection ability according to the number.

Further, in the above embodiment, the case where a plurality of light transmitters are provided and one light receiver is provided has been described.
It is also possible to use a single divergence angle and provide a plurality of light receivers having different light receiving field characteristics in the horizontal direction.

Further, the detection effect may be improved by using a detecting means for detecting the distance of a plurality of light receiving pulses within a certain beam.

In the above embodiment, the radar system using the laser beam is described, but the invention is not limited to this.
Of course, other radar methods such as radio waves and ultrasonic waves may be used.

〔The invention's effect〕

As described above, the present invention includes the transmitting means, the direction distance measuring means, the tracking preceding vehicle setting means, and the first tracking preceding vehicle resetting means for performing the following vehicle following control. When the preceding vehicle following control is performed by using each of these means, it is identified that the tracking preceding vehicle does not exist in the front direction of the own vehicle, and the front direction of the own vehicle approaches the own vehicle. Since a second tracking preceding vehicle resetting means is provided so that the other preceding vehicle can be reset as a tracking preceding vehicle when another preceding vehicle being detected is detected, for example, on a two-lane road. If the lane change is attempted to overtake another preceding vehicle that is slower than the preceding vehicle traveling in front of the same lane during tracking, the other preceding vehicle is newly set as the tracking preceding vehicle. Can be redone.
Along with this, it is possible to avoid the situation in which the host vehicle becomes too close to the other preceding vehicle that has become the new tracking preceding vehicle.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a configuration diagram of a preceding vehicle detection device showing an embodiment of the present invention, FIG. 3 is a flow chart showing an operation of the preceding vehicle detection device of FIG. FIG. 4 is a diagram showing a specific example of the detection state of the preceding vehicle, and FIG. 5 is a time chart in the specific example. 1 ...... vehicle, 2 ...... transmitting means 3 _l to 3 _n, 3X ...... reflector 4 ...... direction distance measuring means 5 ...... tracking the preceding vehicle setting means 6 ...... first tracking the preceding vehicle resetting means 7 ...... Second tracking preceding vehicle resetting means

Claims (1)

[Claims] 1. A transmitting means for transmitting an electromagnetic wave in at least two different horizontal directions including a front direction of the own vehicle and a front direction of the own vehicle, and receiving a reflected wave of the electromagnetic wave transmitted by the transmitting means from a reflector, A direction signal indicating the direction of the reflector with respect to the host vehicle is output from the reflected wave reception direction, and the distance from the host vehicle to the reflector is determined based on the propagation delay time from the electromagnetic wave transmission time to the reflected wave reception time. Directional distance measuring means for calculating and outputting a distance signal, based on distances at the time of the previous measurement and the current measurement based on the distance signal from the direction distance measuring means, and time required to obtain the distances, If the speed difference between the host vehicle and the reflector is calculated, and this speed difference is within a preset required value,
Tracking preceding vehicle setting means for setting the reflector as a tracking preceding vehicle, and the second or third tracking preceding vehicle set by the tracking preceding vehicle setting means cannot be detected in the first direction.
When a signal indicating that the reflector has been detected in the direction is detected, the distance from the own vehicle to the reflector based on the distance signal from the direction distance detection means is detected from the own vehicle that is no longer detected in the first direction. If the distance is substantially the same as the distance to the tracking preceding vehicle, it is determined that the reflector is the same vehicle as the tracking preceding vehicle, and the tracking preceding vehicle setting means is set again as a new tracking preceding vehicle. A first tracking preceding vehicle resetting means for outputting a resetting signal to the vehicle, and a signal from the first tracking preceding vehicle resetting means detects that there is no tracking preceding vehicle in the front direction of the vehicle and When another preceding vehicle is detected in the front direction of the own vehicle by the direction signal from the distance setting means, another preceding vehicle is detected based on the distance signal of the previous measurement and the distance signal of the present measurement from the direction distance measuring means. Car touches own vehicle When it is determined that the vehicle is approaching, a second tracking preceding vehicle resetting means for outputting a resetting signal to the tracking preceding vehicle setting means so as to reset another preceding vehicle as the tracking preceding vehicle, A preceding vehicle detection device having.