JP2009243899A - Preceding vehicle recognition device and preceding vehicle recognition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recognize a preceding vehicle stably corresponding to an object state, while securing recognition accuracy of the preceding vehicle. <P>SOLUTION: Information of object recognition is acquired by transmitting an electromagnetic wave and receiving a reflected wave from an object. Existence of a preceding vehicle is determined by whether a shape characteristic based on the acquired object recognition information agrees with the shape characteristic of a vehicle or not. Every time when determined that a preceding vehicle exists, a prescribed counter value is added into an integration counter, and the preceding vehicle is recognized when the value in the integration counter reaches a prescribed value or higher. The counter value to be added by a counter integration means is set to be a larger value in proportion to the degree of sureness of determination to be a preceding vehicle. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention detects an object in front of a vehicle by receiving a reflected wave of an electromagnetic wave such as a transmitted laser beam, and recognizes whether or not a preceding vehicle exists based on the characteristics of the detected object. The present invention relates to a recognition device and a preceding vehicle recognition method.

As a technique for recognizing a preceding vehicle, for example, there is a technique described in Patent Document 1. In this technique, the integration of objects is determined from the received reflected wave. Furthermore, the preceding vehicle is accurately recognized by independently determining the vehicle shape probability, the own lane probability, and the recognition stability for the object determined to be integrated.
JP 2004-184332 A

In the prior art, in order to improve recognition accuracy, each determination of vehicle shape probability, own lane probability, and recognition stability is performed independently. For this reason, it may take time to recognize the preceding vehicle. However, depending on the position of the preceding vehicle relative to the own vehicle, such as the distance between the own vehicle and the preceding vehicle is short, it is preferable to make a determination as to whether or not the preceding vehicle is an early one.
Moreover, conditions for satisfying each determination of the vehicle shape probability, the own lane probability, and the recognition stability are different. For this reason, once the vehicle is determined to be a preceding vehicle, the determination of the preceding vehicle and the determination of the non-vehicle may occur intermittently.
The present invention has been made paying attention to the above points, and it is an object of the present invention to stably recognize a preceding vehicle according to the object situation while ensuring the accuracy of recognition of the preceding vehicle.

  In order to solve the above problems, the present invention acquires object recognition information by transmitting an electromagnetic wave in front of the vehicle and receiving a reflected wave from the object. It is periodically determined whether or not there is a preceding vehicle based on whether or not the shape feature information of the object based on the acquired object recognition information matches the shape feature information of the vehicle. Whenever the preceding vehicle means determines that there is a preceding vehicle, the counter value is added to the integration counter. When the value of the integration counter exceeds a predetermined value, it is recognized that the preceding vehicle exists. The counter value added by the counter integrating means is set to a larger value as the probability of the preceding vehicle increases.

  According to the present invention, the counter value is increased as the probability of the preceding vehicle increases, without simply determining the detection time of the object that can be determined as the preceding vehicle. Accordingly, it is possible to recognize the preceding vehicle stably at an early stage in accordance with the state of the object while ensuring the recognition accuracy of the preceding vehicle.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing a configuration of a preceding vehicle recognition device of the present embodiment.
(Constitution)
The preceding vehicle recognition device 1 is mounted on a vehicle. The configuration of the preceding vehicle recognition device 1 will be described with reference to FIG.
The LD 2 (laser diode) emits laser light and outputs it toward the scanner device 3. The LD drive circuit 4 controls the light emission of the LD 2. The LD drive circuit 4 is driven based on a drive signal from the controller 5.

  Based on the drive signal from the controller 5, the scanner device 3 transmits (emits) the laser light incident from the LD 2 so as to scan in front of the vehicle. That is, the scanner device 3 can continuously change the laser beam transmission direction in the vertical direction and the horizontal direction, and transmits the laser beam so as to scan a predetermined scanner range. The transmission direction may be changed continuously using, for example, a polygon mirror. Note that a predetermined range on the left, right, top and bottom in front of the vehicle is a scanner range. The laser beam transmitted from the scanner device 3 is emitted forward in the traveling direction of the host vehicle through the light projecting lens 6.

That is, when the front-rear direction of the host vehicle is the X axis, the scanner device 3 sets a scanner range on a YZ plane perpendicular to the X-axis, and emits laser light so as to scan the scanner range.
Further, the vertical scanning position detection device 7 detects the vertical scanning position of the laser beam transmitted from the scanner device 3 and outputs it to the controller 5. The horizontal scanning position detection device 8 detects the horizontal scanning position of the laser beam transmitted from the scanner device 3 and outputs it to the controller 5.

The PD 9 (photodiode) collects and receives the reflected light that has been reflected by the object in front as a detection target and returned by the light receiving lens 10. Further, the PD 9 outputs a signal corresponding to the light receiving level to the light receiving circuit 11. The light receiving circuit 11 digitizes the signal level of the input reflected light and outputs it to the controller 5.
Further, the yaw rate detection device 12 detects the yaw rate ω of the own vehicle (the turning speed at the time of turning of the own vehicle in the horizontal direction) and outputs it to the controller 5. The yaw rate detection device 12 is composed of, for example, a gyro device.

Further, the vehicle speed sensor 13 detects the vehicle speed of the host vehicle and outputs it to the controller 5.
As shown in FIG. 2, the controller 5 includes an object information acquisition unit 5A, an inter-vehicle distance acquisition unit 5B, an object determination unit 5C, a travel path detection unit 5D, a counter value calculation unit 5E, and a lane stay determination unit 5F. The counter integrating unit 5G, the counter holding unit 5H, and the vehicle authorization unit 5J are provided.

  The object information acquisition unit 5A operates periodically. Then, a drive signal is output to the scanner device 3 and the LD drive circuit 4, and laser light is emitted so as to scan within the scanner range. Also, in synchronization, a numerical value (light reception level) corresponding to each reflected wave reflected from the object by the emission is input from the light receiving circuit 11. Then, a numerical value (light reception level) from the light receiving circuit 11 is stored in the memory 14 corresponding to the scan position input from the vertical scanning position detection device 7 and the horizontal scanning position detection device 8. The distribution of the two-dimensional light reception level stored in the memory 14 becomes object recognition information. This is carried out periodically for one scan. The scan cycle is, for example, 100 msec, and information for object recognition is repeatedly acquired every 100 msec.

The inter-vehicle distance acquisition unit 5B measures and acquires the distance between the object and the vehicle based on the time from when the laser beam is emitted until the reflected light is received based on the received light level stored in the memory 14. To do.
The object determination unit 5C determines whether or not the detected object can be estimated as a vehicle from the object recognition information (two-dimensional information of the light reception level) for one scan stored in the memory 14.
In the present embodiment, the detected object is determined to be a vehicle when it matches one of the following two types of detection determination. When it is not determined as a detected object, the process proceeds to the counter holding unit 5H.

In the first detection judgment, the waveform of the reflected light amount (light reception level) along the horizontal direction (vehicle width direction = Y direction) has two peaks as shown in FIG. 3 (vehicle shape characteristics). In the case of a waveform having two peaks, it is determined as a vehicle. This is based on the fact that a vehicle has a pair of reflectors on the left and right and the amount of reflected light from the reflector is large.
In the second detection determination, the width of an object that can be recognized as one object is detected from the object recognition information for one scan stored in the memory 14, and the object width is the size of a range that can be recognized as a vehicle ( Vehicle shape characteristic), the vehicle is determined.

As illustrated in FIG. 4, the travel path detection unit 5D sets XY coordinates centered on the center of gravity of the vehicle in plan view.
Then, the turning radius R of the own vehicle traveling line is calculated from the yaw rate ω from the yaw rate detection device 12 and the own vehicle speed V from the vehicle speed sensor 13 by the following formula.
R = V / ω
Then, the direction H of the traveling line of the own vehicle is estimated from the turning radius R acquired sequentially, and further, the lane width D having a lateral width from the direction H of the traveling line is set to set the traveling area of the own vehicle. . The lane width is changed according to the distance from the own vehicle as shown in FIG. Here, if the vehicle is traveling straight ahead, the direction H of the travel line is the X-axis direction. On the other hand, when the host vehicle is turning, the direction H of the travel line is inclined from the X-axis direction by an angle corresponding to the turning radius R.

The counter value calculation unit 5E calculates a counter value by a process as shown in FIG.
That is, in step S10, it is determined whether or not there is a preceding vehicle in the travel route area A detected by the travel route detection unit 5D. The position of the preceding vehicle specifies the coordinates of the preceding vehicle in the XY coordinate system from the inter-vehicle distance and the direction with respect to the own vehicle. Then, whether or not the preceding vehicle exists in the traveling road area A is determined based on whether or not the coordinates of the preceding vehicle are located in the traveling road area A. Here, the case where the center of the object in the left-right direction is located in the travel path area A is assumed to exist in the travel path area A.

If it is determined that the preceding vehicle exists in the travel route area A, the process proceeds to step S20. On the other hand, if it is determined that the preceding vehicle does not exist in the travel route area A, the process is terminated and the process returns. In this case, a flag indicating that the preceding vehicle does not exist in the traveling road area A may be set.
In step S20, the stay distance L of the preceding vehicle located in the traveling road area A is calculated. The stay distance L is calculated by the following formula, for example.
Stay distance L = own vehicle speed × calculation sample period The calculation sample period is a calculation sample period after it is determined that a preceding vehicle is present.

  Subsequently, the first counter CNT1 value is calculated from the stay distance L in step S30. The first counter CNT1 value is set to increase as the stay distance L increases. For example, as shown in FIG. 6, the one that changes in a quadratic curve according to the stay distance L is used. Instead of using the stay distance L, a stay time in which a preceding vehicle is present in the travel route area A may be used. In this case, for example, “stay time = calculation sample period” is obtained.

  Next, in step S40, the value of the second counter CNT2 is calculated based on the host vehicle speed and the inter-vehicle distance. For example, a three-dimensional map having the own vehicle speed, the inter-vehicle distance, and the value of the second counter CNT2 as variables is provided in advance. Then, the value of the second counter CNT2 is calculated according to the host vehicle speed and the inter-vehicle distance. The vehicle speed table, which is an element of the three-dimensional map, has a relationship as shown in FIG. That is, the second counter value CNT2 is set to be small in the low speed range and large in the high speed range. Further, the distance table which is an element of the three-dimensional Map has a relationship as shown in FIG. That is, when the inter-vehicle distance is small, the second counter value CNT2 is set to be large, and the second counter value CNT2 is set to be small as the inter-vehicle distance is large.

In step S50, the value of the second counter CNT2 is multiplied by the gain G corresponding to the stay distance L, and the multiplied value is reset to the value of the second counter CNT2, as shown in the following equation. As shown in FIG. 9, the gain G is set so as to increase as the stay distance L increases.
CNT2 ← G × CNT2
In step S60, the select counter of the first counter CNT1 and the second counter CNT2 is executed, and the smaller one of the first counter CNT1 and the second counter CNT2 is set as the addition counter CNT.

In step S70, it is determined whether or not the host vehicle is turning with a radius greater than or equal to a predetermined turning radius. If the vehicle is not turning with a predetermined turning radius or more, the process ends. On the other hand, if the vehicle is turning with a turning radius greater than or equal to the predetermined turning radius, the process proceeds to step S80.
In step S80, the addition counter CNT is set to zero. A negative value corresponding to the turning radius may be set in the addition counter CNT. Thereafter, the process ends.

  The lane stay determination unit 5F operates when the counter value calculation unit 5E ends, and determines whether or not an object determined to be a preceding vehicle exists in the traveling path area A of the own vehicle. When the preceding vehicle is present in the travel route area A, it is determined that the preceding vehicle exists in the lane of the host vehicle, and the process proceeds to the counter integrating unit 5G. On the other hand, when the preceding vehicle does not exist in the traveling road area A, the process proceeds to the counter holding unit 5H.

The counter integration unit 5G adds the addition counter CNT value obtained by the counter value calculation unit 5E to the integration counter S-CNTER as in the following equation.
S-CNTER = S-CNTER + CNT
When the vehicle authorization unit 5J detects that the addition counter CNT has reached a predetermined value or more, for example, 400 or more, the vehicle authorization unit 5J authorizes the preceding vehicle. In addition, the authorization determination information as to whether or not the vehicle is a preceding vehicle is transmitted to another control unit such as inter-vehicle control.
When the counter holding unit 5H does not detect an object for a predetermined time continuously, for example, for 1 second or more, or does not determine that it is a vehicle even if it is detected, or if it does not exist in the traveling road area A even if it is determined as a preceding vehicle Is set to initial clear (for example, set to zero).

This means that if an object is not detected for a predetermined time continuously, for example, less than 1 second, or if it is not detected as a vehicle even if it is detected, or if it is determined that it is a preceding vehicle, it does not exist in the road area A The integration counter S-CNTER stops and holds the counter value.
Here, the object information acquisition unit 5A constitutes an object recognition unit. The object determination unit 5C constitutes a preceding vehicle determination unit. The counter value calculation unit 5E constitutes a counter setting unit. The counter integration unit 5G constitutes a counter integration unit. The vehicle authorization unit 5J constitutes a recognition means. The travel path detection unit 5D constitutes a travel path detection unit.

(Operation)
An example of the operation of the preceding vehicle recognition apparatus 1 will be described with reference to FIG.
At every predetermined calculation sample period, laser light is irradiated to scan a predetermined range in front of the vehicle while receiving reflected light from the object, and information for object recognition in front of the vehicle (two-dimensional light reception level). Information) is periodically acquired (step S100).
Based on the acquired information for object recognition, whether or not the object is a vehicle is determined based on whether or not the shape feature of the object that can be specified from the distribution of the received light intensity matches the shape feature of the vehicle. In the present embodiment, a waveform having two peaks in the vehicle width direction, or whether or not the width of the object is the width of the vehicle is used as the shape characteristic information of the vehicle (step S110).

A counter value is set so as to increase as the stay distance L existing in the traveling road ahead of the host vehicle increases (step S120). At this time, the counter value is increased as the host vehicle speed increases, and the counter is set smaller as the inter-vehicle distance increases (step S120).
In this way, the counter value is changed according to the state of the object determined as the preceding vehicle and the vehicle speed, and the counter is sequentially incremented to the integration counter S-CNTER (step S140). That is, the count value is changed with the certainty of determination as a preceding vehicle, and the count is integrated.
When the integration counter S-CNTER is equal to or greater than a predetermined value, the front object is recognized as a preceding vehicle (steps S150 and S160).

  On the other hand, even if it is determined that the detected object is not a preceding vehicle, or even if it is determined to be a preceding vehicle, it is determined that the detected object is not on the traveling path of the own vehicle (step S170). If not, the integration counter S-CNTER is not initially cleared. This is considered when an object is not temporarily detected due to a vehicle wobble or the like. On the other hand, if the detected object is not determined to be a preceding vehicle for a predetermined time or more, or if it is determined that the detected object is not on the traveling path of the host vehicle even if it is determined to be a preceding vehicle, the accumulated counter S-CNTER is initially cleared (S180).

The calculation of the counter value will be described.
The longer the stay distance L in the traveling road ahead of the host vehicle, the higher the probability of the preceding vehicle. Therefore, the counter value is increased and the vehicle is determined early.
Further, in a region where the host vehicle speed is low, there are many scenes of traveling on a region where there are many roadside structures such as traveling on a general road. In this case, since the probability is low, the counter value is set small so that the vehicle / non-vehicle is not erroneously determined, and the determination time is long. On the other hand, when the host vehicle speed exceeds a certain fixed speed, the target object may be detected, and at the same time, the vehicle may be approaching a distance zone that requires alarm judgment. For this reason, the counter value is increased in a quadratic curve as the host vehicle speed increases.

In a state where the inter-vehicle distance is short (approaching), the counter value is set large so that an object in front of the host vehicle can be quickly determined. On the other hand, when the inter-vehicle distance is large, quick judgment is not always necessary. For this reason, the value of the second counter CNT2 is made smaller as the inter-vehicle distance becomes longer.
Further, by multiplying the value of the second counter CNT2 by a gain G corresponding to the stay distance L, the longer the stay distance L is, the higher the probability is.
The reason why the first counter CNT1 value and the second counter CNT2 value are selected is because the determination is made on the safe side.

(Effect of this embodiment)
(1) The counter value to be added to the integration counter S-CNTER is changed with certainty when determining that the vehicle is a preceding vehicle. Thus, in an unstable state depending on the situation, the object is determined by taking a longer determination time. Moreover, when the probability as a preceding vehicle is high, it can be determined whether it is a preceding vehicle at an early stage.
As a result, this makes it possible to recognize the preceding vehicle stably at an early stage stably in accordance with the state of the object while securing the recognition accuracy of the preceding vehicle.

(2) The counter that is added as the object determined by the object determination unit 5C is assumed to be more likely to be determined as the preceding vehicle as the staying distance L or the staying time in which the object is staying on the traveling road of the host vehicle is longer. Increase the value.
The counter value increases as there is an object determined to be the preceding vehicle continuously on the traveling path of the own vehicle, and can be detected early while ensuring a predetermined recognition accuracy.

(3) The counter value to be added is changed according to the host vehicle speed and the inter-vehicle distance with the object determined to be the preceding vehicle, and the counter value is increased as the host vehicle speed increases and the counter value is decreased as the inter-vehicle distance increases.
Thereby, when it is necessary to determine an object at an early stage, it can be quickly determined by increasing the counter.
That is, in the low speed region, by reducing the counter value, it is difficult to be affected by roadside structures and the like, and a predetermined recognition accuracy is ensured. In the high-speed region, instantaneous determination can be made according to the degree of urgency. Furthermore, since the reliability of the object is high at a short distance, a quick determination can be made. And in the distance, it is possible to avoid misrecognition due to the wobbling of the vehicle traveling path.

(4) When the vehicle is determined to be turning, the counter value to be added is set to zero or a negative value.
While the host vehicle is turning, the vehicle / non-vehicle determination may be repeated. For this reason, the state where the vehicle / non-vehicle recognition determination is repeated is avoided by temporarily stopping or subtracting the integration. (5) When the time during which the object that has not been determined to be a preceding vehicle or the object that has been determined to be a preceding vehicle is not on the traveling path of the host vehicle has reached a predetermined time or longer, the integration counter S-CNTER is set to an initial value.
This makes it possible to reliably determine when there is no preceding vehicle.

(6) When the time when the object not determined as the preceding vehicle or the object determined as the preceding vehicle is not on the traveling path of the own vehicle is less than the predetermined time, the addition of the counter position to the integration counter S-CNTER is stopped.
This makes it possible to continue the recognition determination even when the preceding vehicle cannot be detected for a moment due to the wobbling of the host vehicle or the like. As a result, counting up from the beginning can be prevented, and delaying the recognition determination time can be prevented.
(Modification)
(1) In the said embodiment, the laser beam is illustrated as electromagnetic waves. Other electromagnetic waves such as millimeter waves may be used.

It is a schematic diagram explaining the composition of the preceding vehicle recognition device concerning the embodiment based on the present invention. It is a figure which shows the structure of the controller which concerns on embodiment based on this invention. It is a figure which shows the waveform of a light reception level. It is a figure which shows the example of the traveling path area A of the own vehicle. It is a figure which shows the process of a counter value calculation part. It is a figure which shows the relationship between the stay distance L and a 1st counter. It is a figure which shows the relationship between the vehicle speed of the own vehicle, and a 2nd counter. It is a figure which shows the relationship between a vehicle distance and a 2nd counter. It is a figure which shows the relationship between a stay distance and a gain. It is a figure which shows an operation example.

Explanation of symbols

1 Leading vehicle recognition device 2 LD
DESCRIPTION OF SYMBOLS 3 Scanner apparatus 4 LD drive circuit 5 Controller 5A Object information acquisition part 5B Inter-vehicle distance acquisition part 5C Object determination part 5D Traveling path detection part 5E Counter value calculation part 5F Lane stay determination part 5G Counter integration part 5H Counter holding part 5J Vehicle recognition part 7 Vertical scanning position detection device 8 Horizontal scanning position detection device 11 Light receiving circuit 12 Yaw rate detection device 13 Vehicle speed sensor S Integration counter CNT Addition counter CNT1 First counter CNT2 Second counter G Gain A Traveling road area D Lane width H Traveling line direction L Stay distance R Turning radius V Own vehicle speed ω Yaw rate

Claims (8)

Object recognition means for periodically acquiring object recognition information by transmitting electromagnetic waves in front of the vehicle and receiving reflected waves from the object, and the shape of the object based on the object recognition information acquired by the object recognition means Preceding vehicle determination means for periodically determining whether the object is a preceding vehicle based on whether or not the feature matches a geometric feature as a vehicle;
A counter integration unit that adds a counter value to an integration counter every time the preceding vehicle determination unit determines that a preceding vehicle exists; a recognition unit that recognizes that a preceding vehicle exists when the value of the integration counter exceeds a predetermined value;
With
A preceding vehicle recognition apparatus, comprising: a counter setting unit that increases a counter value added by the counter integrating unit as the probability of the determination by the preceding vehicle determining unit is high. Provided with a travel path detecting means for detecting the travel path of the own vehicle,
The counter setting means determines that the object determined as the preceding vehicle by the preceding vehicle determining means based on the detection by the traveling path detecting means is the preceding vehicle as the stay distance or staying time on the traveling path of the own vehicle is longer. 2. The preceding vehicle recognition apparatus according to claim 1, wherein the counter value to be added is increased on the assumption that the probability of the vehicle is high.   The counter setting means changes the counter value to be added according to the own vehicle speed and the inter-vehicle distance from the object determined to be the preceding vehicle, and increases the counter value as the own vehicle speed increases and increases the counter value as the inter-vehicle distance increases. The preceding vehicle recognition device according to claim 1, wherein the preceding vehicle recognition device is reduced.   4. The counter setting means according to claim 1, wherein when the vehicle is determined to be turning, the counter value to be added is set to zero or a negative value. Leading vehicle recognition device.   The cumulative counter S-CNTER is set to the initial value when the time when the object that the preceding vehicle determination means does not determine as the preceding vehicle, or the object that the preceding vehicle determination means determines as the preceding vehicle is not on the traveling path of the own vehicle becomes a predetermined time or more The preceding vehicle recognition device according to any one of claims 1 to 4, wherein the preceding vehicle recognition device is set.   When the time when the object which the preceding vehicle determination means does not determine as the preceding vehicle or the object which the preceding vehicle determination means determines as the preceding vehicle is less than the predetermined time is less than the predetermined time, the counter to the integration counter S-CNTER The preceding vehicle recognition device according to any one of claims 1 to 5, wherein the addition of the position is stopped.   Periodically, every time the shape feature of the object obtained by transmitting electromagnetic waves in front of the vehicle and receiving the reflected wave from the object matches the shape feature of the vehicle, it is judged as the preceding vehicle and The counter value is added, and when the value of the integration counter exceeds a predetermined value, it is recognized that there is a preceding vehicle, and the higher the probability of determination as the preceding vehicle, the larger the counter value to be added is. To recognize the preceding vehicle.   8. The preceding vehicle recognition method according to claim 7, wherein the certainty of the determination as the preceding vehicle is determined by at least one of a positional relationship with respect to the own vehicle of the object determined as the preceding vehicle or the own vehicle speed.

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