JP2005190375A - White line detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white line detector which provides white line data corresponding to control characteristics which a plurality of traveling support systems request, respectively. <P>SOLUTION: A white line detector 1 is provided with; a camera 10 for picking up an image around a vehicle; a white line extraction part 12 for processing image data picked up by the camera 10 to extract the candidate point of a white line position on a road; a white line data calculation part 13 for obtaining white line data like a lane width on the basis of the extracted candidate point; and a mode discrimination part 14 for discriminating which of a lane deviation alarm mode and a lane maintenance support mode is selected. When the lane deviation alarm mode is selected, the white line data calculation part 13 reduces the time constant of a filter for obtaining white line data and increases an erroneous detection guard value, in comparison with the lane maintenance support mode. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a white line detection device.

  As a driving support system to reduce the driver's driving load, the lane maintenance support system that adds the auxiliary steering torque necessary to drive almost in the center of the lane and the subsequent vehicle position are predicted from the driving situation of the driver. A lane departure warning system has been developed that warns the driver by issuing a warning when it is determined that the vehicle may deviate from the lane.

  In such a driving support system, it is necessary to recognize the lane in which the host vehicle is to travel. As a technique for this, an apparatus that detects a boundary line (white line) that divides a lane by performing image processing on a vehicle front image captured by a camera is known (see, for example, Patent Document 1).

The traveling road detection device described in Patent Document 1 detects a edge having a large luminance change from a road image photographed by a video camera, acquires a binarized edge image, and forms a white line shape such as a straight road or a curved road. The white line is detected by searching for an edge that is determined to be a white line within the search range set in accordance with.
JP-A-9-35198 (page 4-6, FIG. 1)

  In a lane departure warning system in which the movement of the vehicle is left to the driver's steering, high followability is required for changes in road shape and vehicle behavior. On the other hand, a lane keeping support system that is controlled to travel substantially in the center of the lane requires a gentler follow-up than the lane departure warning system. As described above, required control characteristics such as followability differ between the lane departure warning system and the lane keeping support system.

  However, the above-described travel path detection device does not consider obtaining white line data used in each travel support system from white line candidate points according to control characteristics required in each of the plurality of travel support systems. Therefore, when control is executed based on the same white line data obtained by the same white line detection logic in a plurality of systems that require different follow-up characteristics, a warning is issued in a lane departure warning system that requires high follow-up characteristics. On the other hand, in the lane keeping support system, there is a possibility that the robustness is lowered and malfunction occurs.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a white line detection device capable of providing white line data according to control characteristics required by each of a plurality of driving support systems. To do.

  According to the present invention, there is provided a white line detection device including: an imaging unit that captures an image around a vehicle; and image data captured by the imaging unit in a white line detection device in a vehicle having a plurality of driving support control modes that are alternatively selected. White line extraction means for extracting candidate points for white line positions on the road, white line data calculation means for obtaining white line data based on the extracted candidate points, and a plurality of driving support control modes. And a white line data calculating means for calculating the white line data according to the driving support control mode determined by the determining means and the detection target. It is characterized by changing at least one of them.

  According to the white line detection device of the present invention, at least one of a calculation constant for obtaining white line data and a detection target is changed according to the selected driving support control mode. Therefore, white line data can be obtained from the extracted white line candidate points according to the control characteristics of the selected driving support control mode.

  The driving support control modes described above include a lane departure warning mode that issues a warning when the vehicle may deviate from the lane marked by the white line, and alerts the driver, and the vehicle travels in the lane. It is preferable that a lane keeping support mode for supporting the vehicle to be included is included.

  In this case, white line data used in each mode is determined in accordance with the lane departure warning mode and the lane keeping support mode and the control characteristics required by the mode.

  In the white line detection device according to the present invention, when the lane keeping support mode is selected, the white line data calculating unit is more likely to be the own vehicle among the candidate points, compared to the case where the lane departure warning mode is selected. It is preferable to obtain white line data by recognizing the candidate point on the side as a detection target.

  In the lane keeping support mode, unlike the lane departure warning mode, it is not necessary to distinguish and detect each white line constituting the composite line, as long as the center of the lane can be detected. When the lane keeping support mode is selected, the center point of the lane is determined by recognizing the candidate point on the own vehicle side among the extracted white line candidate points, that is, the own vehicle side of the composite line as the detection target. Can be detected.

  In the white line detection device according to the present invention, when the lane departure warning mode is selected, the white line data is allowed to fluctuate more greatly than when the lane keeping support mode is selected. It is preferable that the calculation means sets an operation constant.

  In this way, when the lane departure warning mode is selected, it is possible to improve followability with respect to changes in road shape and vehicle behavior.

  In the white line detection device according to the present invention, when the lane departure warning mode is selected, the white line data calculating unit may set the calculation constant so that the false alarm can be suppressed.

  In the white line detection device according to the present invention, the calculation constant is a time constant of a filter that suppresses fluctuation of the white line data and a false detection guard value that sets a range that the white line data can take, and the white line data calculation means includes a lane departure warning. When the mode is selected, it is preferable to reduce the time constant of the filter and increase the false detection guard value than when the lane keeping assist mode is selected.

  When the lane departure warning mode is selected, the time constant of the filter is reduced and the false detection guard value is increased, thereby improving the followability to changes in road shape and vehicle behavior.

  According to the present invention, since at least one of the calculation constant for obtaining the white line data and the detection target is changed according to the selected driving support control mode, each of the plurality of driving support systems requires It is possible to provide white line data corresponding to the control characteristics to be performed.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the figure, the same reference numerals are used for the same or corresponding parts.

  First, the overall configuration of the white line detection device 1 according to the embodiment will be described with reference to FIG. FIG. 1 is a diagram showing an overall configuration of a driving support system 2 using a white line detection device 1. The white line detection device 1 according to the present embodiment extracts white line candidate points that divide a lane, and outputs white line data used in the driving support system 2 based on the candidate points. The driving support system 2 issues a warning when it is determined that the host vehicle may deviate from the driving lane based on the white line data input from the white line detection device 1, and a lane departure warning that prompts the driver to warn It has a function and a lane maintenance support function that supports the host vehicle to travel in the travel lane, and reduces the driving load on the driver. Details will be described later.

  In the present specification, all white lines and yellow lines (including dotted lines) drawn on the road in order to show the separation of each lane are referred to as “white lines”.

  The white line detection device 1 extracts a white line candidate point that divides a lane by performing image processing on a camera (imaging unit) 10 that captures an image of a landscape in front of the vehicle and acquires image data. In addition, a white line detection ECU 11 that obtains white line data used in the driving support system 2 based on the extracted candidate points is provided.

  The camera 10 is disposed on the upper part of the front window of the host vehicle (for example, the back side of the rearview mirror), and acquires an image in front of the vehicle, that is, an image of a traveling lane in front of the vehicle. The image data acquired by the camera 10 is output to the white line detection ECU 11. The camera 10 may be provided at any position on the vehicle body as long as the front image can be captured.

  The white line detection ECU 11 includes a microprocessor that performs calculations, a ROM that stores a program for causing the microprocessor to execute each process, a RAM that stores various data such as calculation results, and a backup in which the stored contents are held by a 12V battery. It is comprised by RAM etc.

  The white line detection ECU 11 is a white line extraction unit 12 that extracts candidate points of the white line position on the road from the image data acquired by the camera 10, and the driving support system 2 based on the white line candidate points extracted by the white line extraction unit 12. A white line data calculation unit 13 for obtaining white line data to be used, and a mode determination unit 14 for determining a selected control mode according to an operation state of a mode changeover switch 21 described later. The white line extraction unit 12 functions as a white line extraction unit, the white line data calculation unit 13 functions as a white line data calculation unit, and the mode determination unit 14 functions as a determination unit.

  As shown in FIG. 3, the white line data obtained by the white line data calculation unit 13 includes the lateral displacement X from the center of the lane of the vehicle 60, the lateral speed dX / dt, the lane width W of the lane 70, the lane width W of the vehicle 60, and the like. The yaw angle θ with respect to the lane 70, the curve curvature R of the lane 70, the pitch angle ψ with respect to the optical axis of the camera 10, and the like.

  The white line detection ECU 11 is connected to a travel support ECU 20 (to be described later) via a communication line 15, and is configured to be able to exchange data with each other. The white line data obtained by the white line detection ECU 11 is read into the travel support ECU 20 via the communication line 15.

  On the other hand, the driving support ECU 20 is connected to a main switch 22 for turning on and off the main power of the driving support ECU 20 and a mode switch 21 for switching the control mode. The operating state of the mode changeover switch 21 and the open / closed state of the main switch 22 input to the travel support ECU 20 are read into the white line detection ECU 11 via the communication line 15.

  The travel support system 2 includes a travel support ECU 20, an electric power steering ECU (hereinafter referred to as “EMPS ECU”) 30 that controls the assist force applied to the steering, and an engine ECU (hereinafter referred to as “EFI ECU”) that integrally controls the engine. ) 40 and a meter ECU 50 for controlling the display of the meter panel and the like.

  The travel support ECU 20, the EMPS ECU 30, the EFI ECU 40, and the meter ECU 50 are connected to each other via a communication line 25. Data can be exchanged among the travel support ECU 20, the EMPS ECU 30, the EFI ECU 40, and the meter ECU 50 via the communication line 25.

  The driving support ECU 20 includes a microprocessor that performs calculations, a ROM that stores programs for causing the microprocessor to execute each process, and a RAM that stores various data such as calculation results.

  The driving assistance ECU 20 predicts the subsequent vehicle position from the white line data input from the white line detection ECU 11 via the communication line 15 and the driving situation of the driver, and it is determined that the host vehicle may deviate from the driving lane. In this case, a lane departure warning control unit 23 that executes lane departure warning control for outputting a warning signal to the meter ECU 50 is provided. The lane departure warning control unit 23 also executes control to apply a small steering force to the departure avoidance side for a predetermined time when determining lane departure.

  Further, the driving support ECU 20 includes a front estimated vehicle position calculated based on the white line data input from the white line detection ECU 11, a steering angle detected by the steering angle sensor 42 and read via the EFI ECU and the communication line 25, Based on the vehicle speed detected by the vehicle speed sensor 41 and read through the EFI ECU and the communication line 25, a torque (current) value for assisting the steering force for the host vehicle to travel substantially in the center of the lane is calculated. A lane keeping support control unit 24 that executes lane keeping support control that is output to the EMPS ECU 30 is provided.

  A mode changeover switch 21 for switching the control mode is connected to the travel support ECU 20. Then, the driving assistance ECU 20 performs switching between lane departure warning control and lane keeping assistance control according to the operation state of the mode changeover switch 21.

  The meter ECU 50 is connected to a buzzer 51 that emits a warning sound and a warning lamp 52 that blinks at the time of warning. The meter ECU 50 emits a warning sound from the buzzer 51 and blinks the warning lamp 52 based on an alarm signal input from the travel support ECU 20 via the communication line 25. Note that the alarm may be performed by only one of the buzzer 51 and the warning lamp 52.

  The EMPS ECU 30 is connected to a steering actuator 31 that applies assist force to the steering. The EMPS ECU drives the steering actuator 31 according to the torque (current) value input from the travel support ECU 20 via the communication line 25. An electric motor or the like is used as the steering actuator 31.

  Connected to the EFI ECU 40 are a vehicle speed sensor 41 for detecting the vehicle speed, a steering angle sensor 42 for detecting the steering angle of the steering, and the like. The EFI ECU 40 outputs the vehicle speed detected by the vehicle speed sensor 41 and the steering angle detected by the steering angle sensor 42 to the travel support ECU 20 via the communication line 25.

  Next, the operation of the white line detection device 1 will be described with reference to FIG. FIG. 2 is a flowchart showing a processing procedure of white line data calculation processing by the white line detection device 1. This process is repeatedly executed every predetermined time. Note that the processing described below is performed by the white line detection ECU 11 unless otherwise specified.

  In step S100, the control permission flag and the selected control mode are read from the travel support ECU 20 via the communication line 25.

  In step S102, image data captured by the camera 10 is read.

  In the subsequent step S104, it is determined whether or not the control permission flag read in step S100 is set. Here, the control permission flag is set when all the conditions for executing the lane departure warning control or the lane keeping support control are satisfied, such as the main switch 22 being in the ON state and the vehicle speed being equal to or higher than a predetermined value. .

  Here, when the control permission flag is not set, the conditions for executing the lane departure warning control or the lane keeping support control are not satisfied, and the process is temporarily exited. On the other hand, when the control permission flag is set, that is, when it is possible to execute the lane departure warning control or the lane keeping support control, the process proceeds to step S106.

  In step S106, it is determined whether or not the selected control mode is a lane departure warning mode. If it is determined that the lane departure warning mode is selected, the process proceeds to step S110. On the other hand, if it is determined that the lane departure warning mode is not selected, that is, if the lane keeping support mode is selected, the process proceeds to step S108.

  In step S108, an extraction target (detection target) for extracting white line candidate points, a Kalman filter constant (filter time constant) for calculating white line data from white line candidate points while suppressing noise and data variation, and the Kalman filter are output. A false detection guard value for setting a range that white line data can take is set. Here, when the white line is a composite line composed of a division line, a line-of-sight guide line, a merge line, and the like, the white line on the own vehicle side of the composite line is an extraction target. The filter time constant is set to a larger value (for example, 1 second) than when the lane departure warning mode is selected. In addition, the false detection guard value is set to a smaller value (for example, 0.5 m / s at the lateral speed) than when the lane departure warning mode is selected in order to prevent calculation of invalid white line data. The Thereafter, the process proceeds to step S112.

  In step S110, an extraction target for extracting white line candidate points, a Kalman filter constant for calculating white line data from the white line candidate points, and a false detection guard value for setting a possible range of the white line data output from the Kalman filter are set. Here, when the white line is a composite line composed of a division line, a line-of-sight guide line, a merge line, and the like, the white line located at the center of the composite line is an extraction target. The filter time constant is set to a smaller value (for example, 0.5 seconds) than when the lane keeping support mode is selected in order to improve followability with respect to changes in road shape and vehicle behavior. Further, the false detection guard value is set to a larger value (for example, 1.0 m / s at the lateral speed) than when the lane departure warning mode is selected. In order to prevent false alarms, a larger filter time constant may be set, and a smaller false detection guard value may be set.

  In step S112, white line candidate points in the image are extracted by performing edge extraction processing on the image data read in step S102. For example, the average luminance in the image is used as a threshold value, and the pixels whose left pixel luminance is lower than the threshold value and whose right pixel luminance is equal to or higher than the threshold value are extracted as edges. As a result, the pixel position corresponding to the left boundary line of the white line is extracted. The edge extraction is not limited to this. For example, a pixel whose luminance difference with the left pixel is equal to or greater than a threshold value may be extracted as an edge. In these, the pixel position at the position corresponding to the left boundary line of the white line is extracted by extracting the edge that changes from dark to light, but the white line is extracted by extracting the edge that changes from light to dark. Alternatively, the pixel position at the position corresponding to the right boundary line may be extracted.

  Next, in step S114, the lateral displacement from the center of the lane of the vehicle from the white line candidate point extracted in step S112 based on the detection target, the filter time constant and the false detection guard value set in step S108 or step S110. White line data such as X, lateral velocity dX / dt, lane width W, yaw angle θ with respect to the lane of the host vehicle, curve curvature R, and pitch angle ψ with respect to the optical axis of the camera are obtained.

  In subsequent step S116, the white line data such as the lateral displacement X, the lateral speed dX / dt, the lane width W, the yaw angle θ, the curve curvature R, and the pitch angle ψ obtained in step S114 travels via the communication line 15. It is output to the support ECU 20. Thereafter, the process is temporarily exited.

  In the white line detection device 1, when the lane departure warning control is selected, the time constant of the filter is made smaller and the false detection guard value is made larger than when the lane keeping assist control is selected. Therefore, it is possible to improve the followability to changes in road shape and vehicle behavior.

  On the other hand, when the lane keeping assist control is selected, the time constant of the filter is increased and the false detection guard value is decreased as compared with the case where the lane departure warning control is selected. Therefore, calculation of invalid white line data can be prevented.

  Thus, according to the white line detection device 1, the white line data used in each control is obtained according to the control characteristics required by the lane departure warning control and the lane maintenance support control. It is possible to provide white line data corresponding to the control characteristics required by each maintenance support control.

  The driving assistance ECU 20 executes lane departure warning control and lane keeping assistance control based on white line data received via the communication line 15. Next, lane departure warning control and lane keeping support control using white line data will be described.

  The driving support ECU 20 reads the operation state of the mode switch 21. The driving assistance ECU 20 selectively selects and executes lane departure warning control and lane keeping assistance control according to the read operation state of the mode changeover switch 21.

  When the lane departure warning control is selected, the driving support ECU 20 predicts the vehicle position after a predetermined time from the driving condition such as the white line data input from the white line detection ECU 11 and the steering angle input from the EFI ECU, and the own vehicle Is output to the meter ECU 50 when it is determined that there is a risk of deviating from the travel lane. In addition, the driving assistance ECU 20 calculates an assist torque value to be given to the departure avoidance side at the time of lane departure determination and outputs it to the EMPS ECU 30.

  The meter ECU 50 emits a warning sound from the buzzer 51 and blinks the warning lamp 52 based on the warning signal input from the driving support ECU 20. Further, the EMPS ECU drives the steering actuator 31 according to the assist torque value input from the travel support ECU 20. In this way, the driver is warned.

  On the other hand, when the lane keeping assist control is selected, the travel assist ECU 20 determines the estimated vehicle position calculated based on the white line data input from the white line detection ECU 11, the steering angle and the vehicle speed read from the EFI ECU 40. Based on this, a torque value for assisting the steering force for the host vehicle to travel substantially in the center of the lane is calculated and output to the EMPS ECU 30.

  And EMPS ECU30 drives the steering actuator 31 according to the assist torque value input from driving assistance ECU20, and driving | running | working in a driving lane is maintained.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, the connection form and function sharing of the ECUs constituting the white line detection device 1 and the driving support system 2 are not limited to the above embodiment.

It is a block diagram which shows the whole structure of the driving assistance system using the white line detection apparatus which concerns on this embodiment. It is a flowchart which shows the process sequence of the white line data calculation process by the white line detection apparatus which concerns on this embodiment. It is a figure for demonstrating the white line data calculated | required by the white line detection apparatus which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... White line detection apparatus, 2 ... Driving assistance system, 10 ... Camera, 11 ... White line detection ECU, 12 ... White line extraction part, 13 ... White line data calculation part, 15, 25 ... Communication line, 20 ... Driving assistance ECU, 21 ... Mode switching switch, 22 ... main switch, 30 ... EMPS ECU, 31 ... steering actuator, 40 ... EFI ECU, 41 ... vehicle speed sensor, 42 ... steering angle sensor, 50 ... meter ECU, 51 ... buzzer, 52 ... warning lamp.

Claims (6)

In a white line detection device in a vehicle having a plurality of driving support control modes that are alternatively selected,
Imaging means for capturing an image around the vehicle;
White line extraction means for extracting candidate points of white line positions on the road by performing image processing on the image data captured by the imaging means;
White line data calculating means for obtaining white line data based on the extracted candidate points;
Discriminating means for discriminating a driving support control mode selected from the plurality of driving support control modes,
The white line data calculating means changes at least one of an operation constant for obtaining the white line data and a detection target according to the driving support control mode determined by the determining means. apparatus.   The plurality of driving support control modes include a lane departure warning mode that issues a warning when the host vehicle is likely to depart from a lane defined by a white line, and alerts the driver, and the host vehicle travels in the lane. The white line detection device according to claim 1, further comprising: a lane keeping support mode for assisting the vehicle to travel.   The white line data calculating means calculates the candidate points on the own vehicle side among the candidate points when the lane keeping support mode is selected and compared with the case where the lane departure warning mode is selected. The white line detection device according to claim 2, wherein the white line data is obtained by recognizing as a detection target.   The white line data calculating means calculates the white line data so that the white line data is allowed to fluctuate more significantly when the lane departure warning mode is selected than when the lane keeping support mode is selected. 4. The white line detection device according to claim 2, wherein a constant is set.   The said white line data calculation means sets the said operation constant so that a false alarm can be suppressed, when the said lane departure warning mode is selected, The said calculation constant is characterized by the above-mentioned. White line detection device. The calculation constant is a false detection guard value that sets a time constant of a filter that suppresses fluctuation of the white line data and a range that the white line data can take,
When the lane departure warning mode is selected, the white line data calculation means makes the time constant of the filter smaller than when the lane keeping support mode is selected, and sets the false detection guard value. The white line detection device according to claim 2, wherein the white line detection device is enlarged.

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