JPS6236581A - Preceding vehicle detector - Google Patents

Abstract

PURPOSE:To detect any car running ahead on the lane where own car runs accurately, by resetting another car running ahead as tracked car when the previously tracked one has gone away from the front thereof and instead, the new car is approaching it. CONSTITUTION:A direction/distance measuring means 15 receives the reflected wave by a reflecting body for electromagnetic waves transmitted from a transmitting means 13 and outputs a direction signal and distance signal. On the basis of these signals, a tracked ahead-running car setting means 17 sets a reflection body detected in front thereof as tracked ahead-running car. When the tracked car running ahead so far spotted in the first direction is detected no more, a tracked ahead-running car judging means 19 judges the car running ahead detected in the second direction adjacent to the first direction to be the tracked car running ahead. When the tracked car running ahead thus far being detected by the means 19 exists no more and is stead, another car running in front of own car as detected by the means 15 is negative in the relative speed to the own car, a tracked ahead-running car altering means 21 resets this car is tracked car running ahead.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a preceding vehicle detection device that transmits electromagnetic waves in front of one's own vehicle and tracks a preceding vehicle while receiving reflected waves of the electromagnetic waves from the preceding vehicle.

[Technical background of the invention and its problems] A radar device is mounted on a vehicle to detect a preceding vehicle or a vehicle in front of the vehicle, thereby controlling the vehicle's own weight and speed or tracking the preceding vehicle. Various developments are underway (for example,
-7892>. By the way, conventionally, in a device that uses a radar device mounted on a vehicle to track a preceding vehicle, the preceding vehicle detected and tracked by the radar device is traveling in the same lane as the own vehicle. Since it is not possible to determine whether or not the vehicle is traveling in the same lane as the own vehicle, it cannot be detected even if the vehicle deviates from the same lane as the own vehicle and moves into another lane. This means that it is continuously being tracked. As a result, for example, even if after the preceding vehicle moves to another preceding lane, another slower preceding vehicle is traveling in front of the own vehicle's driving lane, this other preceding vehicle will be ignored. Therefore, there is a problem in that it is not possible to accurately detect a true preceding vehicle traveling in the lane in which the host vehicle is traveling.

[Object of the Invention] The present invention has been made in view of the above, and its purpose is to provide a preceding vehicle detection device that always accurately detects a preceding vehicle existing in the lane in which the host vehicle is traveling. It is about providing.

[Summary of the Invention] In order to achieve the above object, the present invention includes a transmitting means 13 that transmits electromagnetic waves in different horizontal directions in front of the host vehicle, receives reflected waves of the transmitted electromagnetic waves by a reflector, and receives the reflected waves of the reflected waves. directional distance measuring means 15 that outputs a direction signal indicating the direction of reception, calculates the distance to the reflector based on the propagation delay time from transmission of the electromagnetic wave to reception of the reflected wave, and outputs the distance signal; Based on the distance signal, the system determines that a reflector detected in the front direction of the vehicle is a vehicle in front of the vehicle, and tracks and precedes the vehicle in front of the vehicle.

A tracking leading vehicle setting means 17 that sets the vehicle as a vehicle, and a tracking leading vehicle that has been detected in a first direction within a predetermined distance change range with respect to the own vehicle based on a direction signal and a distance signal, When the vehicle cannot be detected within the range, the vehicle is within a predetermined distance change range relative to the distance to the tracking preceding vehicle that was detected in the first direction immediately before the vehicle becomes undetectable, and in the first direction. A tracking leading vehicle determination means 19 determines that a preceding vehicle detected in an adjacent second direction is the tracking leading vehicle; It is identified by the direction signal that there is no vehicle in front of the own vehicle, and the direction distance measuring means detects another preceding vehicle in the front direction of the own vehicle, and the relative speed of the detected other preceding vehicle with respect to the own vehicle is a negative value. The gist of the present invention is to include a tracking leading vehicle changing means 21 that resets the other preceding vehicle as the tracking leading vehicle when the following occurs.

[Embodiments of the invention] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 2 shows an embodiment of the present invention, in which the preceding vehicle distance determining means 37 receives a distance signal R1 for the right direction supplied from the radar device 31, a distance signal C1 for the front direction C1 left A right flag R1 front flag indicating the distance signal signal to the target preceding vehicle which is calculated by receiving the direction distance signal fLL and tracking the target preceding vehicle according to the processing described later, and the transmitted laser beam capturing the preceding vehicle. C or left flag and supplies the information to the arithmetic processing means 35, and the arithmetic processing means 35 activates the acceleration/deceleration mechanism 41 based on the host vehicle speed signal V from the vehicle speed sensor 33 and the distance signal signal from the preceding vehicle distance determination means 37. This configuration controls the acceleration and deceleration of the own vehicle.

The radar device 31 is roughly divided into a light output section 43, a light reception section 45, and a control section 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 θR and θ in the right direction and left direction, respectively, with respect to the optical axis in the front direction of the vehicle body.
Optical output device 49 having an optical axis shifted by L (θR=θL)
and 53, for example, three optical output devices. Each optical output device 49.51.53 is a laser diode 55.53.
57.59 and lenses 61, 63.65, and the laser output from the laser diodes 55, 57.59 is transmitted through the lenses 61.63.65 to spread angles θTR, θTlC.
2θTL (θTR=θTO−θTL), intensity LTR,L
vg, LTL (LTR=LTC=LTL). Therefore, the laser is emitted along the optical axis in the front direction of the vehicle body and symmetrically with respect to the optical axis.

The light receiving section 45 captures the light reflected by the reflector of the laser emitted from the light outputting section 43 in this way, and includes a light receiving element 67 and a condensing lens 69 that forms a focal point on the light receiving surface of the light receiving element 67. The configuration has the following. The control unit 47 controls laser emission and light reception to determine the distance and direction to the reflector, and the pulse modulator 71 . amplifier 73
．． This configuration includes a comparator 75 and an arithmetic circuit 77. The pulse modulator 71 sequentially outputs a pulse modulation signal with a pulse width of about 100 nSeC and an emission frequency of KH7 to the laser diodes 55, 57, and 59 to drive and control these, and synchronizes with the output of the pulse modulation signal. The optical radiation signal is output to the arithmetic circuit 77. Amplifier 73 and comparator 75
Amplifies the received light signal obtained by photoelectrically converting the light received by the light receiving element 67, extracts a signal exceeding a set level from the received light signal as a signal reflected by the reflector of the laser emitted from the optical output section 43, and performs the operation. 4 circuit 77. The arithmetic circuit 77 determines the direction and distance of the reflector based on the input time difference between the light emission signal and the reflected signal, so distance calculation is performed using the input time difference using the following equation.

Distance: Ai-III-T/2 Here, ■ is the speed of light (3 x 108 m/sec), and T is the input time difference.

FIG. 3 shows the preceding vehicle distance determining means 37 and the arithmetic processing means 3.
5 is a flowchart showing the processing performed in step 5.

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

The process shown in the flowchart of FIG. 3 is based on the distance signals in each direction detected by the node device 31, and even if the preceding vehicle traveling in the lane of the own vehicle is traveling on a curved road, for example, only the true preceding vehicle is detected. This is a process for tracking while accurately detecting the preceding vehicle.By accurately detecting the preceding vehicle in this way, for example, on a curved road, other vehicles traveling in other lanes can be mistakenly detected as the preceding vehicle. to prevent
This system detects only the true distance between the vehicle in front and the vehicle in front, and is used to maintain an appropriate safe distance between vehicles.

More specifically, the direction and distance signals to the preceding vehicle detected by the center, right, and left laser beams from the light output devices 51, 49, and 53 in the front direction, right direction, and left direction of the own vehicle, that is, the front distance orthogonal C11 right Direction distance value IRi, left direction distance 1
Li (i indicates the passage of time) and based on changes in these distances, the vehicle in front is detected by the central laser beam in order to always know which laser beam is being used to detect the vehicle in front. is set, the central flag C is set to “1”.
”, and if it is detected by the right laser beam, set the right flag R to “1”, and if it is detected by the left laser beam, set the left flag L to “1”. By controlling the flag, it is always possible to clearly understand which laser beam is used to capture the preceding vehicle by displaying the flag, and thereby the preceding vehicle being tracked can be detected without error even on curved roads.

Further, for example, at time t i-1, the center laser beam strikes a preceding vehicle traveling on a straight road at a frontal distance tIC1,1.
If the preceding vehicle enters a right-hand curve road at the next time ti, and the preceding vehicle goes out of the detection range of the center laser beam and is no longer detectable by the center laser beam, the adjacent right laser beam If the beam detects the preceding vehicle at a rightward distance IRi, the preceding vehicle simply curved to the right continuously, so the previous time j +−+
The frontal distance IC detected by the central laser beam at
The rightward distance iR+ detected by the right laser beam at time 1 and time ti does not change that much, and is the same as Haton, or even if it changes, the change is small and is a relatively small predetermined distance. It is considered to be within α. Therefore, the front distance N0i-1 and the rightward distance I
If it is determined that the two distances are the same or the difference between the two distances is within a predetermined distance This makes it possible to identify the vehicle in front that has been detected and tracked. In other words, even if the preceding vehicle that was being tracked enters a curved road and its position relative to the preceding vehicle changes, and the detected laser beam changes, the distance detected by each laser beam, that is, the inter-vehicle distance, will change. It is possible to reliably identify the vehicle in front that has been being tracked based on the degree of lag, and prevents the vehicle from losing sight of the vehicle in front or erroneously identifying another vehicle as the vehicle in front.

In addition, in Figure 4, the preceding vehicle indicated by a hatched rectangle and the own vehicle indicated by a non-hatched rectangle pass from a straight road to a right curved road, return to a straight road, then pass a left curved road and return to a straight road. This figure shows the relationship between the laser beam and the preceding vehicle, which indicates which laser beam detection range the preceding vehicle enters and is detected when traveling on a route returning to , and its changes over time from t1 to t12. FIG. 5 shows the azimuth distance signal for the preceding vehicle detected by the radar device 31 during this series of changes, that is, the front distance value C1, the right direction distance value R1, the left direction distance value, and the center flag C1 right flag R1 at that time. The set content of the left flag L, that is, the relationship between "1" or "0" is calculated from time t1 to t12.
This is what is shown for. The processing flow shown in FIG. 3 and outlined above is based on the following figures: 4 and 5. The processing flow shown in FIG. 4 and FIG. This system reliably detects the vehicle in front of you so that you do not lose sight of the vehicle in front.

As can be seen from Figures 4 and 5, when driving 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 1c is the distance to the preceding vehicle. , and the central flag C is "1". When traveling on a right curve, the preceding vehicle enters the detection range of the right laser beam and is detected by the beam, and the rightward distance value i
R represents the distance to the preceding vehicle, and the right flag R is "1". When driving on a left curve, the preceding vehicle enters the detection range of the left laser beam and is detected by the beam, the left direction distance value LL represents the distance to the preceding vehicle, and the left flag L
is "1". In addition, the direction distance signal jlc, I
Since R and IL are the inter-vehicle distances from the vehicle in front that is being followed, they are maintained at approximately constant values determined by the vehicle speed. When the laser beam is detected, the left direction road 11 [L is changing drastically according to the position of the beam flapper, and the right laser beam is detected to be on the ground lane as shown between time t5-t or t8-tIO. When a running vehicle is detected, the rightward distance QR is not constant, but changes at a considerable speed.

Next, the processing flow shown in FIG. 3 will be explained with reference to FIGS. 4 and 5. The processing flow shown in FIG. 3 is activated and executed every certain period of time, for example, several tens of On+m seconds, by interrupt processing in the microcomputer constituting the preceding vehicle distance determination means 37, and each time the process is activated,
That is, at time t=1, first the radar device 3M) optical output devices 49.51.5 for the right direction, front direction, and left direction of the host vehicle.
Azimuth distance signal to the preceding vehicle detected by the right, center, and left laser beams from 3, that is, the right direction distance value IR+
The front distance value 1c and the left direction distance value uL+ are input in sequence (step 110). In the next step 120, the right direction distance linkage R1-1, the front distance sexual love Ci, which was detected and stored at the time of the previous activation, that is, at time (xl, H),
I, read the leftward distance linkage L l-+ from memory.

In this way, after inputting the rightward distance @uR+ and the frontal distance linkage C1 leftward distance value ILI at the current time 1=1 in step 110, the processing flow starts with the first (steps 130 to 139), and a second processing flow for the preceding vehicle detected by the right laser beam (step 140).
to 146), a third processing flow for the preceding vehicle detected by the left laser beam (steps 150 to 156), and a fourth processing flow for determining whether to cancel the tracking operation for the target preceding vehicle. Inter-vehicle distance to the preceding vehicle l1Wt
Fourth processing flow for setting intersection 1 (step 160-1
81), when the target preceding vehicle is detected and tracked by the right or left laser beam, the central laser beam determines whether there is another preceding vehicle in the front direction of the own vehicle, and the tracking of the present invention is performed. As a result of the fifth processing flow (steps 200-250) realizing the preceding vehicle changing means and the first to third processing, there is no target preceding vehicle, and a new target preceding vehicle is set, and the tracking according to the present invention is performed. The sixth processing flow (steps 300-330) that implements the preceding vehicle setting means runs at a constant speed when the target preceding vehicle is absent, and when the target preceding vehicle exists, it runs at a constant speed. The seventh processing flow (steps 340-370) of accelerating and decelerating according to the distance 11, the right direction distance linkage R1, the front distance value ICIN and the left direction distance value ILi are stored in the memory and used for the next operation cycle. Eighth process to proceed 70-
(Steps 380 and 390). Note that the first to fourth processing flows realize the tracking preceding vehicle determining means of the present invention. Further, the first to fourth processing flows realize the tracking preceding vehicle determining means of the present invention. Also,
The first to sixth processing flows and the eighth processing flow are operations of the preceding vehicle distance determining means 37, and the seventh processing flow is operations of the arithmetic processing means 35.

First, in the first processing flow shown in steps 130-139, in step 130, by checking whether or not the center flag C was "1" at the previous time 11.1, the preceding vehicle is set to the center laser beam. to identify whether or not it has been detected. When the center flag C is "1", the preceding vehicle has been detected by the center laser beam, which means that at time to-t+ in FIGS.
, t4-ty+t+o-t++,
In this state, the preceding vehicle may curve to the right when it encounters a right-curving road, as in the change from time t1 to t2, curve to the left as in the change at time t8, or continue on a straight road without changing. may be running. Therefore, based on the detected and read distance signals in each direction, it is detected in which state the preceding vehicle has proceeded, and a flag R, L or C indicating the detected direction is set and the preceding vehicle is detected. This indicates that the vehicle is being detected by the laser beam in the direction indicated by this flag, ensuring that the vehicle in front is always captured.

That is, in steps 131 to 133, in order to check whether the preceding vehicle is moving to the right as shown in the change at time t1→[2, the right direction distance value IR+ and the front distance c1 are first calculated. Calculate the distance difference from .1,
It is checked whether this distance difference is within a predetermined distance α. As mentioned above, this predetermined distance α is a relatively small value, and more specifically, the predetermined distance α is the time interval between the preceding vehicle and the own vehicle when the processing flow shown in FIG. It is sufficient to use a value with a slight margin for changes in the distance between vehicles, and since the distance between vehicles changes within 1 m when taking into account the range measurement accuracy of the radar installation @31 and vehicle speed, etc., add some margin to this value. The predetermined distance α may be selected to be approximately 4 m.

The result of the check in step 131 is that the distance difference is within the predetermined distance α because the preceding vehicle has curved to the right, and the right laser beam has newly detected the rightward distance value I.
It has been identified that the preceding vehicle with R+ is the same preceding vehicle that was previously detected with the central laser beam and had a frontal distance value IC+-1, and therefore the process proceeds to step 132. In this step 132, the distance difference between the front distance value 1G+ and the front distance linkage CI-1 is highlighted, and it is checked whether this distance difference is within a predetermined distance α. When the preceding vehicle curves completely to the right at time ti and cannot be detected by the central laser beam (that is, when the following preceding vehicle cannot be detected within a predetermined distance change range), the front distance value lC+ is infinite. Therefore, the distance difference between the front distance value 1c1 and the front distance value 1c+-+ is 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 this beam. be done. Therefore, in the next step 133, the center flag C-0, the right flag R=1. The left flag is set to 10, and the process proceeds to step 160.

In addition, if the distance difference between the right direction distance value R1 and the front distance l111IG+-+ is not within the predetermined distance α in step 131, and in step 132, the front distance value l1
If the distance difference between CI and the front distance value uci,+ is within the predetermined distance α, the preceding vehicle does not curve to the right, but instead curves to the left as at time t8 or continues straight ahead. First, in steps 134 to 136, in order to check whether the object curves to the left, the left direction distance value ! L+-
+ and the front distance #i Ai C+-+ is calculated, and it is checked whether this distance difference is within a predetermined distance α.

As a result of the check in step 134, the distance difference is within the predetermined distance α because the preceding vehicle has curved to the left as at time t8, so it is newly detected by the left laser beam and has a left direction distance value of 0-Ll. It has been identified that the preceding vehicle is the same preceding vehicle that has been detected by the central laser beam and has a frontal distance of 1 [no i,+, and therefore the process proceeds to step 135. In this step 135, similarly to step 132, the distance difference between the front distance value IC1 and the front distance value 1c+-+ is calculated, and it is checked whether this distance difference is within a predetermined distance α. If the preceding vehicle completely curves to the left at time H and cannot be detected by the central laser beam, the front distance value!
Since LC+ is infinite, the distance difference between the front distance linkage C1 and the front distance value fLcl-+ is larger than the predetermined distance α, and the preceding vehicle completely enters the detection range of the left laser beam and is detected by the beam. It is determined that it has been detected. Therefore, in the next step 136, the center flag C=O, and the right flag R=O.

, sets flag L=1, and proceeds to step 160.

Further, in step 134, if the distance difference between the left direction distance linkage L1 and the front distance value t1cH is not within the predetermined distance α, and in step 135, the distance difference between the front distance value Act and the front distance value IC1a is within the predetermined distance α. In this case, there is a possibility that the preceding vehicle does not make a left curve but continues straight ahead, so proceed to step 137 and calculate the frontal distance ff1lc+ and the frontal distance III I O
The distance difference from i-+ is calculated, and it is checked whether this distance difference is within a predetermined distance α. This distance difference is the predetermined distance α
The fact that the preceding vehicle is within the time [1] also means that the preceding vehicle is within the time [1].
Since it is determined that the center laser beam is detected in the same way as above, the process proceeds to step 138 and the center flag C-1, right flag R=O, and left flag L-0 are set as before. The process then proceeds to step 160.

Further, in step 137, if the distance difference between the front distance value 1c: and the front distance [uC+, τ is not within the predetermined distance α, the preceding vehicle may be in another driving lane where the preceding vehicle cannot be detected by any laser beam, as at time t12, for example. etc., and it can be determined that the preceding vehicle is gone, so proceed to step 139 and set the center flag C=O and the right flag R=0.
．． The left flag L-0 is set to indicate that there is no preceding vehicle, and the process proceeds to step 160.

Further, as a result of checking the central flag C in step 130, if the central flag C=0, step 1
Proceeding to step 40, it is checked whether the right flag R is "1". When the right flag R is "1", the preceding vehicle is making a right curve and is detected only by the right laser beam, which is at time t2-t3 in FIGS. 4 and 5.

This is the case at tll-t12, and in this state, the preceding vehicle may return to running straight after curving to the right as at time t4, or may continue to curve to the right without changing.

Therefore, if the right flag R=1, first step 141
~143, in order to check whether the preceding vehicle has returned to running straight after curving to the right as at time t4, first, the distance between the front distance value ILC+ and the right direction distance value uRi,+ is determined. A difference is calculated, and it is checked whether this distance difference is within a predetermined distance α. As a result of the check in step 141, the fact that the distance difference is within the predetermined distance α means that the preceding vehicle has returned to driving straight from the right curve. It has been identified that the preceding vehicle is the same as the preceding vehicle that has been detected by the right laser beam and has the rightward distance value uR+-+, and therefore the process proceeds to step 142. In this step 142, the distance difference between the rightward distance value IR+ and the rightward distance value R+, + is calculated, and it is checked whether this distance difference is within a predetermined distance α. If the preceding vehicle completely returns to running straight at time ti and cannot be detected by the right laser beam, the rightward distance value IR+ is infinite. The distance difference becomes larger than the predetermined distance α, and it is determined that the preceding vehicle has completely entered the detection range of the central laser beam and is detected by the beam. Therefore, in the next step 143, the center flag C-1, the right flag R-0, and the left flag L=O are set, and the process proceeds to step 160.

Further, if the distance difference between the front distance value fLc1 and the rightward distance linkage R1,1 is not within the predetermined distance α in step 141, and in step 142, the rightward distance linkage R1.
If the distance difference between and the right direction distance linkage Ri-+ is within the predetermined distance α, the preceding vehicle may not have returned to driving straight from the right curve but is continuing the right curve, so step The process proceeds to step 144, where the distance difference between the rightward distance value 1rz and the rightward distance value IRg is calculated, and it is checked whether this distance difference is within a predetermined distance α. The fact that this distance difference is within the predetermined distance α means that it has been determined that the preceding vehicle is being illuminated by the right laser beam at time ti as well as at time 1 +-1, so the process proceeds to step 145 and the center Flag C=O, right flag R=1, left flag L=
Set O to the same value as before and proceed to step 160.

Further, in step 144, the right direction distance adjustment 111
If the distance difference between the distance and the right direction distance intersection Rh+ is not within the predetermined distance α, it can be determined that the preceding vehicle has moved to another driving lane that cannot be detected by any laser beam and the preceding vehicle is gone, so step 146 Go to center flag C
-0, right flag R=0, and left flag L=O to indicate that there is no preceding vehicle, and the process proceeds to step 160.

Further, as a result of checking the right flag R in step 140, if the right flag R=O, step 150 is performed.
It is checked whether the left flag L is "1" or not. When the left flag L is rlJ, the preceding vehicle is making a left curve and is detected only by the left laser beam, but this is due to the time t in Figures 4 and 5.
, -t9. In this state, the preceding vehicle may return to running straight after curving to the left as at time t9, or may continue to curve to the left without changing.

Therefore, if the left flag L=1, first step 15
1 to 153, in order to check whether the preceding vehicle is curved to the left as at time t9 and returns to running straight, first, the front distance value 1c+ and the left direction distance value tLi-+what distance A difference is calculated, and it is checked whether this distance difference is within a predetermined distance α. As a result of the check in step 151, the fact that the distance difference is within the predetermined distance α means that the preceding vehicle has returned to driving straight from the left curve, and the preceding vehicle with the front distance linkage C1 is newly detected by the central laser beam. It has been identified that the preceding vehicle is the same as the preceding vehicle that has been detected by the left laser beam and giving the left direction distance value uL+-+, and therefore the process proceeds to step 152. In this step 1.52, the distance difference between the leftward distance linkage 1-1 and the leftward distance value 11-+-+ is calculated, and it is checked whether this distance difference is within a predetermined distance α. If the preceding vehicle completely returns to running straight at time ti and cannot be detected by the left laser beam, the leftward path MliljtLi is infinite, so the leftward distance value IL+ and the leftward distance liI! The distance difference from Ai L1.1 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 being detected by the beam. Therefore, next step 15
3, center flag C-1, right flag R=O1 left flag L=
0 and proceed to step 160.

Further, in step 151, the front distance value ILc1 and the left direction distance value L1. If the distance tIi difference with f is not within the predetermined distance α, J3 and step 152, if the distance difference between the left inward distance linkage L1 and the leftward distance linkage Lbl is within the predetermined distance α, the preceding vehicle Since there is a possibility that the vehicle is continuing the left curve rather than returning to straight driving from the left curve, the process proceeds to step 154 and calculates the distance difference between the left direction distance value uL+ and the left direction distance value iL1.1. , it is checked whether this distance difference is within a predetermined distance α. The fact that this distance difference is within the predetermined distance α means that it has been determined that the preceding vehicle is using the left laser beam at time ti as well as at time j +-1, so step 1
Step 55 is followed by setting the center flag C=O, right flag R=O8, and left flag L=1 as before, and the process proceeds to step 160.

Further, if the distance difference between the leftward distance value L1 and the leftward distance value fLL+-+ is not within the predetermined distance α in step 154, the preceding vehicle moves to another driving lane where it cannot be detected by any laser beam. Since it can be determined that the central flag C- is gone, the process proceeds to step 156 and
0, right flag R=O.

The left flag is set to L=O to indicate that there is no preceding vehicle, and the process proceeds to step 160.

As described above, the first. The vehicle that has reliably detected the target preceding vehicle through the second and third processing flows, and has tracked the preceding vehicle while marking the detected laser beam with the center flag C1, right flag R, or left flag, Proceeding to step 4, the inter-vehicle path 1111 with respect to the target preceding vehicle is set.

That is, in steps 160, 170, and 180, it is checked which flag C, R, or L was set in the first to third processing flows, and the azimuth distance value corresponding to the set flag, that is, the front distance is determined. Value I Cl
, set the rightward distance 1auR+ or the leftward distance linkage L1 as the distance statement (steps 161 and 171).
．． 181>.

Here, if flag C=1 and the target leading vehicle is detected by the central laser beam, the process proceeds to the seventh process flow, and if no flag is set and the target leading vehicle is absent, the process proceeds to the sixth process flow. However, if flag R=1 or flag L=1 and the target preceding vehicle is detected by the right or left laser beam, the process proceeds to the next fifth processing flow,
While tracking a target preceding vehicle with the right or left laser beam, it is detected whether another preceding vehicle newly exists within the range detected by the frontal laser beam.

First, in step 200, based on the temporal change in the front distance detected so far, it is determined whether the front distance value 1G+ is the distance to the preceding vehicle or the distance to the roadside object. Discrimination is made using the method disclosed in No. If it is determined that the distance is the same as that of the preceding vehicle, the process proceeds to step 210, and the momentary inter-vehicle distance fLc+-9,
1CI-8, . . . , lc+ −+ , IC+ to calculate the relative speed ΔV with respect to the preceding vehicle. Then, check whether the calculated relative speed △V is negative (step 220); if it is negative, it means that the own vehicle is approaching the preceding vehicle. is further the inter-vehicle distance intersection with the preceding vehicle detected by the frontal laser beam c1
It is checked whether or not is shorter than a predetermined inter-vehicle distance H (step 230). If it is short, the preceding vehicle detected by the frontal laser beam is judged to be more dangerous to the own vehicle than the target preceding vehicle that was being tracked up until now, so the center flag C-1, right Flag R-0° Left flag L-
0, the target preceding vehicle to be tracked is changed to the preceding vehicle detected by the frontal laser beam, and the frontal distance value 1c+ detected by the frontal laser beam is set as the following distance value 1 (step 240, 2°50). , proceed to the seventh processing flow. Furthermore, if the preceding vehicle cannot be detected in the check at step 200, or if the relative speed ΔV is positive in the check in step 220, that is, if the distance from the preceding vehicle is increasing, the front vehicle is detected by the front laser beam in the check in step 230. If the distance 1G+ from the preceding vehicle is greater than the predetermined inter-vehicle distance TH, it is considered that there is no preceding vehicle with a high degree of danger, so the process proceeds to the seventh processing flow without changing the tracking preceding vehicle.

In addition, as a result of detecting the preceding vehicle with the front laser beam and calculating its relative speed Δ■ in steps 200 and 210, the relative speed ΔV is negative and the distance to the preceding vehicle is 1G + the predetermined inter-vehicle distance m. If it is shorter than the intersection TH, it is determined that the preceding vehicle detected by the front laser beam is more dangerous to the own vehicle than the target preceding vehicle that was being tracked until now, but this judgment is limited to this criterion. For example, let the inter-vehicle distance Ml■1-( be a function of the relative speed △V (for example, QrH=Ai1+△■, where k is a positive constant), and determine whether uc+<iv++ holds. It is also possible to use this as a criterion for judgment.

Further, if the target preceding vehicle cannot be detected in the first to third processing flows and none of the flags are set, the process proceeds from the fourth processing flow to step 300 of the sixth processing flow. In step 310, the following step 310 calculates the front distance 1f from the temporal change in the front distance detected so far using the same process as step 200.
11ii Determine whether I C+ is the distance to the preceding vehicle or the distance to a roadside object. If the distance is from the preceding vehicle, the preceding vehicle is set as the target preceding vehicle to be tracked from now on, and the front flag C,=1 and the right flag R-0. The left flag L-0 is set, the front distance linkage Cl detected by the front laser beam is set to the following distance, and the process proceeds to step 340 of the seventh processing flow.

In step 340 of the seventh processing flow, it is checked whether the front flag is C-1.

When the flag C=l, the front laser beam captures and tracks the preceding vehicle. In this case, the acceleration/deceleration α is calculated according to the intermediate distance intersection 1 to the preceding vehicle. Acceleration/deceleration α is expressed as −α0〈α＜+aO (for example, ao = 31
v/h/sec) and outputs it (step 360).

In addition, if flag C is not 1, it means that the right or left laser beam other than the frontal laser beam captures and tracks the preceding vehicle, but in this case, the acceleration is Acceleration/deceleration α limited to below a predetermined ω
−α0・α〈+αth (for example, αth= 1 km
/h/sec) and outputs it (step 350).

In step 310, if it is not possible to detect that the vehicle is in the lead, the process proceeds to step 370, where a constant speed driving control command is output to cause the own vehicle to travel at a constant speed.

In the eighth processing flow, the right direction distance value IR1, the front distance value fLCi, and the left direction distance value IL input in step 110+stored in the memory (step 380),
Then, the cycle of the interrupt time is incremented by one, and the process ends (step 390).

In the above embodiment, the case where the number of laser beams is three was explained, but other number of beams, for example, two,
4,5. . . . etc. may be selected, and the preceding vehicle detection ability can be expected to correspond to the number.

In addition, in the above embodiment, the case where a plurality of light transmitters are provided and one light receiver is provided, but the light transmitter has a high output,
It is also possible to use one light receiver with a widening angle and provide a plurality of light receivers with different light receiving field characteristics in the horizontal direction.

Furthermore, the detection effect may be increased by using a detection means that detects the distance of a plurality of received light pulses within a certain beam.

Further, in the above embodiment, a radar system using a laser beam is described, but the present invention is not limited to this, and it goes without saying that other radar systems such as radio waves and ultrasonic waves may be used.

[Effect of the invention].

As explained above, according to the present invention, when the preceding vehicle that was being tracked deviates from the front of the own vehicle, another preceding vehicle is detected in the front direction of the own vehicle, and When the vehicle is approaching the vehicle with a negative speed, the vehicle in front of the vehicle in front of the vehicle is set as the vehicle in front of the vehicle. Even if there is another slower preceding vehicle in the lane in which the own vehicle is traveling, the system will reliably detect that other preceding vehicle and track the other preceding vehicle anew. Therefore, it is possible to achieve safe driving without ignoring the other preceding vehicle and approaching it abnormally.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to claims of the present invention, FIG. 2 is a configuration diagram of a preceding vehicle detecting device showing an embodiment of the present invention, FIG. 3 is a flowchart showing the operation of the preceding vehicle detecting 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. 13... Transmission means 15... Direction distance measuring means 17... Pursuing preceding vehicle setting means 19... Pursuing preceding vehicle determining means 21... Pursuing preceding vehicle changing means FIG.

Claims (1)

[Claims] A transmitting means for transmitting electromagnetic waves in different horizontal directions in front of the host vehicle, and receiving reflected waves of the transmitted electromagnetic waves by a reflector,
directional distance measuring means for outputting a direction signal indicating the receiving direction of the reflected wave, and calculating a distance to the reflector based on a propagation delay time from transmission of the electromagnetic wave to reception of the reflected wave and outputting a distance signal; , a tracking leading vehicle setting means for determining that a reflector detected in the front direction of the own vehicle is a preceding vehicle with respect to the own vehicle based on the direction signal and the distance signal, and setting the preceding vehicle as a tracking leading vehicle; When the tracking preceding vehicle, which was detected in the first direction within a predetermined distance change range relative to the own vehicle based on the distance signal, can no longer be detected within the predetermined distance change range; Tracking the preceding vehicle that is detected in a second direction adjacent to the first direction and within a predetermined distance change range with respect to the distance to the pursued preceding vehicle that was detected in the first direction immediately before. It is identified by the direction signal that the following preceding vehicle, which is detected based on the judgment of the following preceding vehicle determining means and the following preceding vehicle determining means, does not exist in the front direction of the host vehicle, and Another preceding vehicle is detected in the front direction of the own vehicle by the direction distance measuring means, and when the relative speed of the detected other preceding vehicle with respect to the own vehicle is a negative value, the other preceding vehicle is set as a tracking preceding vehicle. 1. A preceding vehicle detection device comprising: means for changing the tracking preceding vehicle.