JP2006335224A - Preceding vehicle detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly redetect a preceding vehicle on its own lane when lane deviation prevention control is operated after the detected preceding vehicle is switched. <P>SOLUTION: A preceding vehicle detection device presumes a lane on which its own vehicle travels based on a yaw rate after filter processing for smoothing the change of the yaw rate, and detects the preceding vehicle within the presumed lane. After the detected preceding vehicle is switched, when lane deviation prevention control for controlling the vehicle so that its own vehicle can be prevented from deviating from its own lane, the characteristics of filter processing are reduced so that the level of smoothing of the change of the yaw rate can be reduced. Thus, it is possible to quickly redetect a preceding vehicle 12 on its own lane for a presumed lane 21 before the change of the filter characteristics within a presumed lane 22 after the change of the filter characteristics. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for estimating a host lane based on a yaw rate of a vehicle and detecting a preceding vehicle in the estimated host lane.

  Conventionally, a control for detecting a preceding vehicle and maintaining a distance between the preceding vehicle and a lane departure prevention control for controlling the vehicle so as not to deviate from the lane when the host vehicle is likely to deviate from the driving lane. A device that is used in combination is known (see Patent Document 1). There is also known a technique in which the preceding vehicle is detected in the own lane estimated based on the yaw rate and vehicle speed detected by the yaw rate sensor. In this own lane estimation technology, in order to prevent the estimated lane from fluctuating due to slight fluctuations in the yaw rate, the yaw rate detected by the yaw rate sensor is filtered, and the change of the yaw rate is detected. A technique for reducing the responsiveness of change is also known.

JP 2003-306135 A

  Here, before the lane departure prevention control is activated, a vehicle existing on the lane in which the host vehicle is traveling may be lost or a vehicle traveling in the adjacent lane may be switched as a preceding vehicle. In this case, even if the lane departure prevention control is activated and the host vehicle can stay in the host lane, the filter processing reduces the response of the estimated lane change to the change in the yaw rate of the vehicle. There is a problem that it takes time to detect again the preceding vehicle on the own lane that has been lost first in the estimated lane.

  The preceding vehicle detection device according to the present invention estimates a lane in which the host vehicle travels based on a yaw rate that has been subjected to filter processing so that a change in the yaw rate becomes gradual, and detects a preceding vehicle in the estimated lane. When the lane departure prevention control for controlling the vehicle so that the own vehicle does not deviate from the own lane is performed after losing sight of the detected preceding vehicle, the yaw rate changes slowly. The characteristic of the filter processing is changed so that the degree becomes smaller.

  According to the preceding vehicle detection device of the present invention, when the lane departure prevention control is performed after losing sight of the detected preceding vehicle, the characteristics of the filter processing are reduced so that the degree of gradual change in the yaw rate is reduced. Therefore, when the vehicle direction changes due to the operation of the lane departure prevention control, it is possible to quickly detect the preceding vehicle that has been lost.

  FIG. 1 is a diagram illustrating a configuration of a preceding vehicle detection device according to an embodiment. The preceding vehicle detection device in one embodiment is used by being mounted on a vehicle, and includes an inter-vehicle distance sensor 1, a vehicle speed sensor 2, a yaw rate sensor 3, a throttle actuator 4, a brake actuator 5, A camera 6 and a control device 7 are provided.

  The inter-vehicle distance sensor 1 includes a radar device, sends a laser beam to a predetermined range in front of the vehicle at predetermined intervals, and receives reflected light that is reflected back to the preceding vehicle, thereby allowing the inter-vehicle distance to the preceding vehicle. Is detected. The vehicle speed sensor 2 detects the speed of the host vehicle. The yaw rate sensor 3 detects the yaw rate of the vehicle, that is, the speed at which the vehicle rotates.

  Based on the yaw rate detected by the yaw rate sensor 3 and the vehicle speed detected by the vehicle speed sensor 2, the control device 7 estimates a road (own lane) on which the host vehicle will travel from now. A known method can be used for estimating the own lane. At this time, when estimating the own lane, the yaw rate detected by the yaw rate sensor 3 is filtered so that the estimated lane does not fluctuate due to slight fluctuations in the yaw rate. This filter can be realized by, for example, a low-pass filter.

  FIG. 2 is a diagram showing a flow of processing for estimating the own lane by the control device 7. The control device 7 includes a filter processing unit 7a and a lane estimation unit 7b for processing functions performed internally. The filter processing unit 7a performs a filtering process so that the yaw rate changes gradually with respect to the yaw rate detected by the yaw rate sensor 3. The lane estimation unit 7b estimates the own lane based on the yaw rate subjected to the filtering process and the vehicle speed detected by the vehicle speed sensor 2. Specifically, the curvature of the own lane is calculated, and information on the width of the own lane is added to estimate the own lane. Thus, by estimating the own lane using the yaw rate after the filter processing, it is possible to prevent the estimated lane from fluctuating with respect to a slight fluctuation in the yaw rate. That is, the estimated own lane changes slowly with respect to the actual change in the yaw rate.

  The control device 7 also detects a preceding vehicle existing in the own lane estimated by the above-described method based on the laser light transmitted and received by the inter-vehicle distance sensor 1, and the own vehicle follows the detected preceding vehicle. Then, the preceding vehicle follow-up control for automatic traveling is performed. That is, based on the inter-vehicle distance detected by the inter-vehicle distance sensor 1 and the speed of the own vehicle detected by the vehicle speed sensor 2, the throttle is set so that the inter-vehicle distance between the own vehicle and the preceding vehicle is maintained at a constant distance. The actuator 4 and the brake actuator 5 are controlled.

  The camera 6 images the front of the host vehicle. The control device 7 performs known image processing (for example, white line detection processing) on the image captured by the camera 6, thereby defining a lane (travel lane) in which the host vehicle is traveling (for example, (White line) is detected, and if it is determined that the vehicle is likely to deviate from the detected line, a braking force is applied to the wheels so that a yaw moment in a direction that prevents lane departure acts on the vehicle. That is, by applying braking force to the wheels on the opposite side of the lane departure direction from the left and right wheels, departure from the lane is prevented. This lane departure prevention control is a known control. The yaw moment with respect to the vehicle is calculated based on the vehicle speed, the lateral position of the vehicle in the lane, the yaw angle with respect to the lane, and the like. Since a well-known technique can be adopted for this in Japanese Patent Application Laid-Open No. 2003-112540 and the like, detailed description is omitted here.

  In the preceding vehicle detection device according to the embodiment, when the lane departure prevention control is activated after losing sight of the preceding vehicle detected in the estimated lane, the filter processing unit 7a is activated when the lane departure prevention control is activated. Change the characteristics of the filtering process to be performed.

  FIG. 3 is a diagram illustrating a state in which a vehicle traveling on the own lane is missed and a vehicle traveling on an adjacent lane is erroneously detected as a preceding vehicle before the lane departure prevention control is activated. As shown in FIG. 3, when the direction of the vehicle 11 is shifted from the straight traveling direction to the right side, the own lane 20 estimated based on the yaw rate and the vehicle speed is also shifted to the right direction. Therefore, the preceding vehicle detected in the estimated lane is Then, the vehicle 12 on the own lane is switched to the vehicle 13 traveling in the adjacent lane.

  FIG. 4 is a diagram showing a lane estimated by the lane estimation unit 7b when the lane departure prevention control is activated and the direction of the vehicle is changed. Depending on the characteristics of the filter processing performed by the filter processing unit 7a, FIG. Shows two lanes. A lane 21 indicates an estimated lane when the filter processing characteristics are not changed. As described above, since the filtering process is performed so that the yaw rate changes gradually with respect to the yaw rate detected by the yaw rate sensor 3, the responsiveness of the estimated lane change is low with respect to the yaw rate change. It has become.

  On the other hand, the lane 22 indicates an estimated lane in which the characteristics of the filter processing are lowered so that the degree of gradual change in the yaw rate is reduced. By reducing the characteristics of the filter processing, as shown in FIG. 4, the responsiveness of the estimated lane change to the yaw rate change is increased, so that the preceding vehicle 12 can be quickly detected again in the estimated lane 22. it can.

  Note that the filter processing characteristic is changed by the filter processing unit 7a. As described above, when the characteristics of the filter processing are lowered, the degree of gradual change in the yaw rate is reduced, so that the responsiveness of the estimated lane change to the change in the yaw rate is increased. On the contrary, when the characteristics of the filter processing are increased, the degree of gradual change in the yaw rate increases, so that the response of the estimated lane change to the change in the yaw rate decreases.

  In the preceding vehicle detection device in one embodiment, the characteristics of the filter processing when the lane departure prevention control is activated are changed according to the yaw moment applied to the vehicle by the lane departure prevention control.

  FIG. 5A is a diagram showing the relationship between the yaw moment generated in the vehicle when the lane departure prevention control is activated (the yaw moment in the direction to prevent lane departure) and the characteristics of the filtering process. FIG. 5B is a diagram showing the relationship between the yaw moment generated in the vehicle when the lane departure prevention control is operated and the responsiveness of the estimated lane change to the yaw rate change. As the yaw moment generated in the vehicle becomes smaller, the characteristics of the filter processing are lowered so that the response of the estimated lane change to the yaw rate change becomes higher. As a result, since the yaw moment generated in the vehicle is small when the lane departure prevention control is activated, even if the degree of change in the direction of the vehicle is small, the vehicle traveling in the own lane is quickly detected as the preceding vehicle. Can be redone.

  As described above, the preceding vehicle is detected in the lane estimated based on the vehicle speed and the yaw rate. Here, a lane for detecting the preceding vehicle and a lane for determining that the detected preceding vehicle is lost are set separately. FIG. 6 is a diagram showing a lane 61 for detecting a preceding vehicle and a lane 62 for determining that the detected preceding vehicle has been lost. As shown in FIG. 6, the lane 62 for determining that the preceding vehicle has been lost is set outside the lane 61 for detecting the preceding vehicle. Thereby, it is possible to prevent the detection of the preceding vehicle and the loss (missing) from being frequently switched.

  In the preceding vehicle detection device according to the embodiment, when the lane departure prevention control is further activated, it is determined that the lane 61 for detecting the preceding vehicle and the preceding vehicle are lost based on the yaw rate generated in the vehicle. The lane width of each lane 62 is changed.

  FIG. 7 is a diagram showing the relationship between the yaw moment generated in the vehicle during the lane departure prevention control and the lane width of the lane 61 for detecting the preceding vehicle. As shown in FIG. 7, the lane width of the lane 61 for detecting the preceding vehicle is increased as the yaw moment generated in the vehicle decreases. As a result, the vehicle running in the adjacent lane is erroneously detected as the preceding vehicle before the lane departure prevention control is activated, and the yaw moment generated in the vehicle when the lane departure prevention control is activated is small. Even when the degree of change in the direction of the vehicle is small, the vehicle traveling in the own lane can be quickly detected again as the preceding vehicle.

  FIG. 8 is a diagram showing the relationship between the yaw moment generated in the vehicle during the lane departure prevention control and the lane width of the lane 62 for determining that the preceding vehicle has been lost. As shown in FIG. 8, the lane width of the lane 62 for determining that the preceding vehicle has been lost is made smaller as the yaw moment generated in the vehicle becomes smaller. As a result, the vehicle running in the adjacent lane is erroneously detected as the preceding vehicle before the lane departure prevention control is activated, and the yaw moment generated in the vehicle when the lane departure prevention control is activated is small. Even when the degree of change of the direction of the vehicle is small, the erroneously detected vehicle can be removed from the estimated lane as soon as possible.

  FIG. 9 is a flowchart showing the contents of processing performed by the preceding vehicle detection device in one embodiment. The control device 7 starts the control in step S10 when starting the preceding vehicle following control based on the command from the driver. In step S10, it is determined whether or not the preceding vehicle detected by the preceding vehicle following control has been switched, or whether or not it has been lost (lost). As described with reference to FIG. 3, the preceding vehicle that is traveling on the own lane is overlooked, and the vehicle that is traveling on the adjacent lane is detected as the preceding vehicle. If it is determined that there is, the process proceeds to step S20, and if it is determined that the preceding vehicle has not been switched, the process waits in step S10.

  In step S20, it is determined whether or not the lane departure prevention control is activated within a predetermined time (for example, 2 seconds) after the preceding vehicle is switched or lost. Here, it is determined that the lane departure prevention control is activated when it is determined that the host vehicle is about to depart from the traveling lane. If it is determined that the lane departure prevention control is activated, the process proceeds to step S30. If it is determined that the lane departure prevention control is not activated, the process returns to step S10.

  In step S30, the characteristics of the filter processing performed by the filter processing unit 7a are changed based on the yaw moment generated in the vehicle during the operation of the lane departure prevention control and the correlation shown in FIG. The control device 7 calculates the yaw moment generated in the vehicle during the operation of the lane departure prevention control according to the state of the vehicle. Note that the relationship between the yaw moment generated in the vehicle and the filter characteristics shown in FIG. 5A may be obtained in advance through experiments or the like and stored in a memory (not shown) of the control device 7. When the filter characteristic is obtained based on the yaw moment generated in the vehicle when the lane departure prevention control is activated, the process proceeds to step S40.

  In step S40, the lane width of the lane 61 for detecting the preceding vehicle based on the yaw moment generated in the vehicle during the operation of the lane departure prevention control and the response characteristics shown in FIGS. 7 and 8, respectively, The lane width of the lane 62 for determining that the vehicle has been lost is obtained. The relationship between the yaw moment generated in the vehicle and the lane width shown in FIGS. 7 and 8 may be obtained in advance through experiments or the like and stored in a memory (not shown) of the control device 7. Based on the yaw moment generated in the vehicle when the lane departure prevention control is activated, the lane width of the lane 61 for detecting the preceding vehicle and the lane width of the lane 62 for determining that the preceding vehicle has been lost are respectively obtained. When each lane width is changed to the obtained lane width, the process proceeds to step S50.

  In step S50, when the preceding vehicle is switched in step S10, it is determined whether or not the switched preceding vehicle is lost. If it is determined that the preceding vehicle is not lost, the process returns to step S10. If it is determined that the preceding vehicle is lost, the process proceeds to step S60. In step S60, a command is issued to the brake actuator 5 so that the vehicle decelerates for a predetermined time.

  In general, if the preceding vehicle is lost while the preceding vehicle tracking control is operating, control is performed to accelerate the vehicle in order to make the vehicle speed coincide with a predetermined vehicle speed. However, when the lane departure prevention control is operating, the braking force is applied to the wheels so that the yaw moment in the direction to prevent lane departure acts on the vehicle, so while the braking force is applied to the vehicle, You may lose sight of the preceding car temporarily. Therefore, if the preceding vehicle can be detected again during the predetermined time by performing the control that the vehicle decelerates only for the predetermined time, the vehicle behavior does not change significantly without unnecessary acceleration. Following control can be resumed.

  In the present embodiment, the timing for applying the yaw moment to the vehicle by the lane departure prevention control is step S20, and the filter characteristics are changed during the application of the yaw moment. For example, a new step may be added between step S40 and step S50.

  The preceding vehicle detection device in one embodiment estimates the own lane based on the filtered yaw rate, detects the preceding vehicle in the estimated own lane, and is likely to deviate from the own lane If it is determined, the vehicle is controlled so that the own vehicle does not deviate from the own lane. In such an apparatus, when the lane departure prevention control is performed after losing sight of the detected preceding vehicle, the characteristics of the filter processing are lowered so that the degree of gradual change in the yaw moment is reduced. Therefore, the responsiveness of the estimated lane change to the yaw rate change becomes high, and the vehicle traveling on the own lane can be quickly detected again as the preceding vehicle.

  According to the preceding vehicle detection device in one embodiment, the filter processing characteristics are lowered so that the smaller the yaw moment generated in the vehicle during the lane departure prevention control, the smaller the degree of gradual change in the yaw rate. As a result, since the yaw moment generated in the vehicle is small during the operation of the lane departure prevention control, even if the degree of change in the direction of the vehicle is small, the vehicle running on the own lane is quickly set as the preceding vehicle. Can be detected again.

  Further, according to the preceding vehicle detection device in one embodiment, when the lane departure prevention control is performed after losing sight of the detected preceding vehicle, the estimated lane width of the own lane is widened. A vehicle on the own lane can be quickly detected again as a preceding vehicle. At this time, the smaller the yaw moment generated in the vehicle during the lane departure prevention control, the larger the proportion of the lane width that is widened. Therefore, the yaw moment generated in the vehicle during the operation of the lane departure prevention control is small. Even when the degree of change is small, it is possible to quickly re-detect the vehicle traveling on the own lane as the preceding vehicle.

  According to the preceding vehicle detection device in the embodiment, the lane (lost determination lane) for determining that the detected preceding vehicle is lost is set outside the estimated own lane, and the lane departure prevention control is performed. When this is done, the lane width of the lost judgment lane will be narrowed, so if the vehicle traveling in the adjacent lane is mistakenly detected as the preceding vehicle before the lane departure prevention control is activated, it will be erroneously detected as the preceding vehicle. The vehicle that is being operated can be removed from the lost determination lane as soon as possible. At this time, the smaller the yaw moment generated in the vehicle during the lane departure prevention control, the larger the ratio of narrowing the lane width of the lost judgment lane, so the yaw moment generated in the vehicle is small. Even when the vehicle is small, a vehicle erroneously detected as a preceding vehicle can be removed from the lost determination lane as soon as possible.

  According to the preceding vehicle detection device in one embodiment, when the preceding vehicle is lost when the lane departure prevention control is activated, the vehicle decelerates for a predetermined time, so that the preceding vehicle is detected again during the predetermined time. If possible, the preceding vehicle follow-up control can be resumed without unnecessary acceleration.

  The present invention is not limited to the embodiment described above. For example, the preceding vehicle is detected by transmitting and receiving laser light from the inter-vehicle distance sensor 1, but it can also be performed based on transmission / reception of signals other than laser light, or other devices can be used. it can. For example, a camera that captures the front of the vehicle may be mounted on the vehicle, and a preceding vehicle existing in the estimated lane may be detected based on an image captured by the in-vehicle camera.

  In the above-described embodiment, the filter processing characteristics and the lane width are changed based on the yaw moment generated in the vehicle when the lane departure prevention control is operated. However, after the lane departure prevention control is operated, the yaw rate sensor is changed. Based on the yaw rate detected by No. 3, the characteristics of the filtering process and the lane width may be changed.

  In the flowchart shown in FIG. 9, when the lane departure prevention control is activated after the preceding vehicle detected by the preceding vehicle following control is switched, the filter characteristics and the lane width are changed. The filter characteristics and the lane width may be changed when the lane departure prevention control is activated after the detected preceding vehicle is lost without switching. In this case, since the preceding vehicle has been lost, the lane width of the lost determination lane may not be changed. Further, the filter characteristics and the lane width may be changed only when the lane departure prevention control is activated during a predetermined time after losing sight of the detected preceding vehicle.

  In the lane departure prevention control, the braking force is applied to the wheels so that the yaw moment in the direction to prevent the lane departure acts on the vehicle, but the lane departure may be prevented by operating the steering. In other words, the lane departure can be prevented by turning the steering to the side opposite to the lane departure direction. In addition to the image processing, the lane (white line) may be detected using, for example, an infrared sensor. Furthermore, not only the deviation from the lane, but also a deviation from the road (asphalt road surface) may be detected.

  Although a low-pass filter has been described as an example of a filter for performing the filter processing, a filter other than the low-pass filter may be used.

  The correspondence between the constituent elements of the claims and the constituent elements of the embodiment is as follows. That is, the yaw rate sensor 3 is the yaw rate detection means, the control device 7 is the lane estimation means, the preceding vehicle detection means, the lane departure prevention control means, the filter characteristic change means, the lane width change means, the lost determination lane setting means, and the lost determination lane width. As the changing means, the control device 7 and the brake actuator 5 constitute vehicle control means. In addition, the above description is an example to the last, and when interpreting invention, it is not limited to the correspondence of the component of said embodiment and the component of this invention at all.

The figure which shows the structure of the preceding vehicle detection apparatus in one embodiment. The figure which shows the flow of the process which estimates an own lane by a control apparatus The figure which shows a mode that the detected preceding vehicle switched before lane departure prevention control act | operated. The figure which shows the lane estimated by the lane estimation part, when the lane departure prevention control actuates and the direction of the vehicle changes FIG. 5A is a diagram showing a relationship between the yaw moment generated in the vehicle when the lane departure prevention control is operated and the characteristics of the filter processing, and FIG. 5B is a diagram when lane departure prevention control is operated. Is a diagram showing the relationship between the yaw moment generated in the vehicle and the response of the estimated lane to changes in the yaw rate A diagram showing a lane for detecting a preceding vehicle and a lane for determining that the preceding vehicle being detected is lost. The figure which shows the relationship between the yaw moment generated in a vehicle at the time of lane departure prevention control, and the lane width of the lane for detecting a preceding vehicle The figure which shows the relationship between the yaw moment generated in a vehicle at the time of lane departure prevention control, and the lane width of the lane for determining that the preceding vehicle has been lost. The flowchart which shows the processing content performed by the preceding vehicle detection apparatus in one embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vehicle distance sensor, 2 ... Vehicle speed sensor, 3 ... Yaw rate sensor, 4 ... Throttle actuator, 5 ... Brake actuator, 6 ... Camera, 7 ... Control apparatus

Claims (8)

Yaw rate detection means for detecting the yaw rate of the vehicle;
A lane estimation unit that estimates a lane in which the host vehicle travels by performing a filtering process such that a change in the yaw rate becomes gentle with respect to the yaw rate detected by the yaw rate detection unit;
Preceding vehicle detection means for detecting a preceding vehicle in the lane estimated by the lane estimation means;
A lane departure prevention control means for generating a yaw moment so that the host vehicle does not deviate from the own lane when it is determined that the host vehicle is about to deviate from the own lane;
Control that prevents the vehicle from deviating from the own lane by the lane departure prevention control unit after the preceding vehicle detected by the preceding vehicle detection unit is lost or the preceding vehicle is switched (hereinafter referred to as lane departure) And a filter characteristic changing unit that changes the characteristics of the filter processing (hereinafter referred to as filter characteristics) so that the degree of gradual change in the yaw rate is reduced. Leading vehicle detection device. In the preceding vehicle detection device according to claim 1,
The filter characteristic changing means changes the filter characteristic such that the smaller the yaw moment generated in the vehicle during the operation of the lane departure prevention control, the smaller the degree to which the change in the yaw rate becomes gradual. Leading vehicle detection device. In the preceding vehicle detection device according to claim 1 or 2,
When the lane departure prevention control is performed by the lane departure prevention control means after losing sight of the preceding vehicle detected by the preceding vehicle detection means, the lane width of the lane estimated by the lane estimation means is increased. A preceding vehicle detection device further comprising lane width changing means. In the preceding vehicle detection device according to claim 3,
The preceding lane width changing means increases the ratio of widening the lane width as the yaw moment generated in the vehicle during the operation of the lane departure prevention control is smaller. In the preceding vehicle detection apparatus in any one of Claims 1-4,
Lost determination lane setting means for setting a lane (hereinafter referred to as a lost determination lane) for determining that the preceding vehicle being detected has been lost outside the lane estimated by the lane estimation means;
The lost determination lane set by the lost determination lane setting means when the lane departure prevention control is performed by the lane departure prevention control means after losing sight of the preceding vehicle detected by the preceding vehicle detection means. A preceding vehicle detection device, further comprising lost determination lane width changing means for narrowing the lane width of the vehicle. In the preceding vehicle detection device according to claim 5,
The preceding vehicle detection device characterized in that the lost determination lane width changing means increases the ratio of narrowing the lane width of the lost determination lane as the yaw moment generated in the vehicle during the operation of the lane departure prevention control is smaller. . In the preceding vehicle detection apparatus in any one of Claims 1-6,
Vehicle control means is further provided for controlling the vehicle to decelerate for a predetermined time when the preceding vehicle detected by the preceding vehicle detection means is lost when the lane departure prevention control is activated. Leading vehicle detection device. In the preceding vehicle detection device that estimates the lane in which the host vehicle travels based on the yaw rate that has been subjected to the filter processing so that the change in the yaw rate becomes gradual, and detects the preceding vehicle in the estimated lane,
If lane departure prevention control is performed to control the vehicle so that it does not deviate from its own lane after the previous vehicle being detected has been lost or the preceding vehicle has been switched, the yaw rate changes slowly. The preceding vehicle detection device characterized in that the characteristic of the filter processing is changed so that the degree becomes smaller.

Images