JP2017056796A - Lane maintaining control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continue adequately lane maintaining control even when reference position correction is being implemented in a camera unit.SOLUTION: A controller 8 as a lane maintaining control device acquires, from a camera unit 20 obtaining plural parameters including at least a vehicle condition specified to a traveling lane, the plural parameters, calculates a target position to which a vehicle is to be traveled for lane maintaining on the basis of the acquired plural parameters, calculates a target yaw rate which is to be generated in the vehicle for the vehicle to travel the calculated target position, and implements vehicle steering control so as to generate the calculated target yaw rate in the vehicle. When the camera unit 20 is implementing vehicle reference position correction on the basis of a disappearing point, the controller 8 calculates the target position through making the contribution degree of the parameter obtained from the reference position among the plural parameters smaller than the case of not being implementing reference position correction.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a lane keeping control device, and more particularly, to a lane keeping control device for performing lane keeping control of a vehicle.

  2. Description of the Related Art Conventionally, there has been known a technique for providing driving assistance to a driver so as to maintain the own vehicle in a traveling lane (in other words, to suppress deviation from the own lane). For example, Patent Document 1 predicts the future lateral position of the host vehicle after a predetermined time, and the lateral position is more than the predetermined lane width direction position defined with reference to the detected lane marking. There is disclosed a lane keeping control device that gives a vehicle a yaw moment toward the center side of its own lane when it is located on the outside as viewed from the center side. In particular, in this lane keeping control device, when the lane markings cannot be detected or when the recognition degree is low, the application of the yaw moment is suppressed compared to when the lane markings are normally detected. .

JP 2010-52716 A

  By the way, conventionally, a plurality of parameters including the state of the vehicle with respect to the traveling lane, the form of the traveling lane, and the like are obtained from the captured image of the scenery in front of the vehicle captured by the camera, and lane keeping control is performed based on these parameters. ing. For example, the plurality of parameters are obtained on the camera unit side including a camera that captures a landscape in front of the vehicle. Further, some of the plurality of parameters are obtained based on a vehicle reference position (a position used as the center of the vehicle) defined by a vanishing point in the forward scenery. For example, the yaw angle indicating the direction in which the vehicle is facing the traveling lane corresponds to a parameter obtained based on such a reference position.

  On the other hand, the reference position described above is corrected as needed based on the vanishing point by detecting the vanishing point while the vehicle is traveling. This is because the posture of the vehicle changes according to the tire pressure of the vehicle, the occupant arrangement in the passenger compartment, etc., and the reference position to be used as the center of the vehicle changes. If the parameters (for example, the yaw angle) obtained based on the reference position being corrected are used as they are while the reference position is being corrected in this way, appropriate lane keeping control may not be executed. In order to prevent this, there may be a method of stopping the lane keeping control while the reference position is being corrected, but this is not desirable because the purpose of the lane keeping control cannot be achieved.

  The present invention has been made to solve the above-described problems of the prior art, and a lane capable of appropriately continuing the lane keeping control even during the correction of the reference position in the camera unit. An object is to provide a maintenance control device.

In order to achieve the above object, the present invention is a lane keeping control device for performing lane keeping control of a vehicle, which captures a front landscape of the vehicle and defines a vehicle state defined with respect to the traveling lane A parameter acquisition means for acquiring a plurality of parameters from a camera unit for obtaining a plurality of parameters including at least a target position to be caused to travel by the vehicle for lane keeping based on the plurality of parameters acquired by the parameter acquisition means Calculated by a target yaw rate calculating means, a target yaw rate calculating means for calculating a target yaw rate to be generated by the vehicle in order to cause the vehicle to travel the target position calculated by the target position calculating means, and a target yaw rate calculating means. Steering control means for performing steering control of the vehicle so that the target yaw rate is generated in the vehicle. When the camera unit corrects the reference position of the vehicle based on the vanishing point in the forward landscape, the target position calculation means is configured to set a plurality of parameters as compared with the case where the camera unit does not correct the reference position. The target position is calculated by reducing the contribution of the parameter obtained from the reference position.
In the present invention configured as described above, when the camera unit corrects the reference position based on the vanishing point, a plurality of images input from the camera unit are compared to when the camera unit does not correct the reference position. Of these parameters, the target position is calculated by reducing the contribution of the parameter obtained from the reference position, so that appropriate lane keeping control can be continued even during correction of the reference position by the camera unit. Specifically, according to the present invention, by using the parameter obtained according to the reference position being corrected as it is, it is possible to prevent the appropriate lane keeping control from being performed, In order to prevent this, the lane keeping control can be suppressed from being stopped, and the lane keeping control can be continued.

In the present invention, it is preferable that the parameter obtained from the reference position among the plurality of parameters is a yaw angle indicating a direction in which the vehicle is facing the traveling lane, and the target position calculation unit is configured such that the camera unit has the reference position. When the correction is performed, the target position is calculated by reducing the contribution of the yaw angle compared to the case where the camera unit is not correcting the reference position.
In the present invention configured as described above, the yaw angle indicating the direction in which the vehicle is facing the traveling lane is obtained based on the reference position applied as the center of the vehicle. When the correction is made in step (b), the contribution of the yaw angle obtained from the reference position is reduced. Thereby, it becomes possible to continue lane maintenance control more appropriately.

In the present invention, preferably, in addition to the yaw angle, the plurality of parameters include a curvature of a traveling lane, a curvature of a clothoid curve corresponding to the traveling lane, and a lateral position indicating a lateral position of the vehicle in the traveling lane. When the camera unit is correcting the reference position, the target position calculation means reduces only the contribution of the yaw angle, and each of the curvature of the traveling lane, the curvature of the clothoid curve, and the lateral position The target position is calculated while maintaining the contribution degree.
According to the present invention configured as described above, when the camera unit is correcting the reference position, only the contribution of the yaw angle is reduced, the curvature of the traveling lane, the curvature of the clothoid curve, and the lateral position Since each degree of contribution is maintained, an accurate target position can be calculated even during correction of the reference position.

  According to the lane keeping control device of the present invention, it is possible to appropriately continue the lane keeping control even when the reference position is corrected in the camera unit.

1 is a diagram illustrating a schematic configuration of a vehicle including a lane keeping control device according to an embodiment of the present invention. It is a block diagram which shows the electric constitution of the vehicle provided with the lane keeping control apparatus by embodiment of this invention. It is a block diagram which shows the flow of the process in lane maintenance control by embodiment of this invention. It is a block diagram which shows the flow of the process of target position calculation by embodiment of this invention. It is explanatory drawing about the yaw angle and lateral position which are used in embodiment of this invention. It is a flowchart which shows the correction process of the reference position which a camera unit performs in embodiment of this invention. It is a flowchart which shows the lane maintenance control which the controller in a vehicle performs in embodiment of this invention.

  Hereinafter, a lane keeping control device according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[Device configuration]
With reference to FIG.1 and FIG.2, the structure of the lane keeping control apparatus by embodiment of this invention is demonstrated. FIG. 1 is a diagram illustrating a schematic configuration of a vehicle including a lane keeping control device according to an embodiment of the present invention, and FIG. 2 illustrates an electrical configuration of the vehicle including a lane keeping control device according to an embodiment of the present invention. FIG.

  As shown in FIG. 1, a vehicle 1 according to an embodiment of the present invention mainly includes a steering wheel 2 operated by a driver, a steering shaft 4 having one end connected to the steering wheel 2, and the steering shaft 4. A rack and pinion type steering gear device 10 having the other end connected thereto, and left and right steering wheels 12 connected to the steering gear device 10 and steered by the operation of the steering gear device 10 are provided. The vehicle 1 also includes an electric power steering mechanism (torque actuator) 6 that applies torque (steering assist torque) to the steering shaft 4 and a controller 8 that controls the steering assist torque applied by the electric power steering mechanism 6. Also have.

  Next, as shown in FIG. 2, the controller 8 mainly includes a vehicle speed sensor 14 for detecting the vehicle speed of the vehicle 1, a yaw rate sensor 16 for detecting the yaw rate of the vehicle 1, and the steering wheel 2 (FIG. 1). The steering angle sensor 18 that detects the steering angle of the camera 1 and a camera unit 20 that includes a camera (not shown) that captures the front landscape of the vehicle 1 are electrically connected. In addition to the camera, the camera unit 20 includes a microcomputer (not shown) that processes an image taken by the camera.

  In the present embodiment, the controller 8 supplies a control signal to the electric power steering mechanism 6 based on signals input from the vehicle speed sensor 14, the yaw rate sensor 16, the steering angle sensor 18, and the camera unit 20. By applying a desired steering assist force from the steering mechanism 6 to the steering shaft 4, lane keeping control of the vehicle 1 is executed. Therefore, the controller 8 corresponds to the “lane keeping control device” in the present invention. Although details will be described later, the controller 8 functions as “parameter acquisition means”, “target position calculation means”, “target yaw rate calculation means”, and “steering control means” in the present invention.

[Lane maintenance control]
Next, the lane keeping control according to the embodiment of the present invention will be specifically described with reference to FIGS. FIG. 3 is a block diagram showing a process flow in the lane keeping control according to the embodiment of the present invention, and FIG. 4 is a block diagram showing details of the target position calculation process in FIG.

  As shown in FIG. 3, a signal mainly output from the camera unit 20 is input to the controller 8. Specifically, the camera unit 20 performs image processing (analysis) on a photographed image of the scenery in front of the vehicle photographed by the camera, thereby indicating a plurality of states of the vehicle 1 and the form of the traveling lane defined for the traveling lane. The controller 8 receives the plurality of parameters thus obtained by the camera unit 20. And the controller 8 is based on the several parameter input from the camera unit 20, and in order to maintain the vehicle 1 in a driving | running | working lane, the target position which the vehicle 1 should drive (in other words, the point which should guide the vehicle 1) Is calculated. Details of the calculation of the target position will be described later.

Next, the controller 8 calculates a target yaw rate to be generated in the vehicle 1 in order to cause the vehicle 1 to travel at the target position described above, and when the steering angle (target steering angle) corresponding to the target yaw rate is achieved, the vehicle A self-aligning torque (a moment around the vertical axis among moments generated when the tire is skidding) is calculated. In this case, the controller 8 calculates the slip angle of the vehicle 1 from the steering angle corresponding to the target yaw rate, and calculates the self-aligning torque from the slip angle. Next, the controller 8 adds the self-aligning torque and the target yaw rate obtained from the target position described above to perform a target yaw rate to be finally generated from the vehicle 1 (hereinafter referred to as “final target yaw rate” as appropriate). ").) Is calculated.
In calculating the target yaw rate and the self-aligning torque, the controller 8 determines the vehicle speed detected by the vehicle speed sensor 14, the yaw rate detected by the yaw rate sensor 16, the steering angle detected by the steering angle sensor 18, and the like. Various sensor values shall be used as appropriate.

  Next, the controller 8 obtains a steering assist torque to be applied to the steering shaft 4 from the final target yaw rate in order to cause the vehicle 1 to generate the final target yaw rate calculated as described above. Then, the controller 8 executes control (steering control) on the electric power steering mechanism 6 so that the obtained steering assist torque is applied to the steering shaft 4.

  Next, with reference to FIG. 5 in addition to FIG. 4, the target position calculation process according to the embodiment of the present invention will be specifically described. FIG. 5 is an explanatory diagram of the yaw angle and the lateral position used in the embodiment of the present invention.

As shown in FIG. 4, from the camera unit 20 to the controller 8, the curvature of the clothoid curve corresponding to the traveling lane, the curvature of the traveling lane itself, and the yaw angle indicating the direction in which the vehicle 1 faces the traveling lane, The lateral position indicating the lateral position of the vehicle 1 in the travel lane is input. The clothoid curve is a curve in which the product of the radius of curvature R and the curve length L from the clothoid start point is a constant “R × L = A ² ”. This “A” is a constant having a dimension of length “clothoid parameter (The clothoid curve is applied to the curve curve of many roads). The curvature of the clothoid curve input from the camera unit 20 to the controller 8 indicates a change in the curvature of the traveling lane.

  Here, with reference to FIG. 5, the above-described yaw angle and lateral position will be specifically described. As shown in FIG. 5, the yaw angle is defined as an angle θ formed by a travel lane L1 of the vehicle (own vehicle) 1 and a center line L2 passing through the center of the vehicle 1 in the width direction. In other words, it is defined as an angle θ at which the traveling direction of the vehicle 1 (the direction in which the center line L2 extends) and the traveling lane L1 intersect. Further, the lateral position is defined based on the distance between each of the two traveling lanes L1 located on both sides of the vehicle 1 and the center in the width direction of the vehicle 1 (see reference numeral A1 in FIG. 5).

  Returning to FIG. 4, the description of the target position calculation process is resumed. The camera unit 20 shoots a landscape in front of the vehicle 1 with a built-in camera (a landscape including at least a traveling lane in front of the vehicle), and captures a captured image obtained by shooting with a built-in microcomputer. By performing image processing (analysis), the curvature of the clothoid curve, the curvature of the traveling lane, the yaw angle, and the lateral position are obtained. In particular, the camera unit 20 detects the vanishing point of the forward scenery from the captured image, and uses the vanishing point as a reference position that is the center of the vehicle 1 to obtain the yaw angle of the vehicle 1. In this case, the camera unit 20 includes, in the captured image, a line (corresponding to the center line L2 shown in FIG. 5) extending in the vertical direction with the reference position corresponding to the detected vanishing point as a reference, The angle at which the traveling lane intersects is obtained as the yaw angle.

  Further, the camera unit 20 repeatedly performs a process of detecting the vanishing point from the captured image and correcting the reference position based on the vanishing point while the vehicle 1 is traveling. More specifically, when the currently used reference position (stored reference position) is deviated from the detected vanishing point, the camera unit 20 performs processing for correcting the reference position by the vanishing point. This is repeated during the straight running of No. 1, specifically during the period except when the steering wheel 2 is being steered and when the yaw rate sensor 16 is detecting the yaw rate. As described above, the camera unit 20 corrects the reference position as needed because the posture of the vehicle 1 changes according to the tire air pressure of the vehicle 1 or the occupant arrangement in the passenger compartment, and the reference position to be used as the center of the vehicle 1 changes. Because.

  Next, the controller 8 controls the vehicle 1 to maintain the vehicle 1 in the traveling lane based on the curvature of the clothoid curve, the curvature of the traveling lane, the yaw angle, and the lateral position obtained by the camera unit 20 as described above. A target position to be traveled is calculated. In this case, the controller 8 first calculates various terms used for calculating the target position. Specifically, the controller 8 uses, for example, a predetermined arithmetic expression defined in advance, a clothoid term corresponding to the clothoid curve, a curvature term corresponding to the curvature of the traveling lane, and a yaw angle term corresponding to the yaw angle The horizontal position term corresponding to the horizontal position is calculated. Next, the controller 8 obtains gains (fixed values may be used for each of the calculated clothoid term, curvature term, yaw angle term, and lateral position term) (fixed values or various situations). It may be a value that changes according to the above). Then, the controller 8 adds the plurality of values obtained by multiplying the gains in this way, and further multiplies the values obtained by the addition processing by the gains to obtain the target position.

  Here, in this embodiment, when the camera unit 20 is performing the process of correcting the reference position as described above, the controller 8 is when the camera unit 20 is not performing the process of correcting the reference position. In comparison, the target position is calculated by reducing the gain value applied to the yaw angle term (that is, reducing the gain). That is, the controller 8 reduces the contribution of the yaw angle applied when calculating the target position. In other words, the controller 8 calculates the target position in consideration of the curvature of the clothoid curve, the curvature of the traveling lane, and the lateral position, rather than the yaw angle. In this way, the yaw angle obtained from the reference position being corrected is used as it is while the lane keeping control is continuously performed even while the camera unit 20 is performing the process of correcting the reference position. In this way, it is possible to prevent the appropriate lane keeping control from being performed.

[Control flow]
Next, the control flow executed in the embodiment of the present invention will be specifically described with reference to FIGS.

  FIG. 6 is a flowchart showing a reference position correction process performed by the camera unit 20 in the embodiment of the present invention. This flow is repeatedly executed at a predetermined cycle by the camera unit 20 (specifically, a microcomputer in the camera unit 20).

  First, in step S11, the camera unit 20 detects the vanishing point in the captured image by analyzing the captured image of the scenery in front of the vehicle captured by the built-in camera. For example, the camera unit 20 detects, as a vanishing point, a portion in which pixel values hardly change in two or more captured images that are temporally continuous. In step S12, the camera unit 20 stores the vanishing point detected in step S11.

  Next, in step S13, the camera unit 20 compares the vanishing point position stored in step S11 with the currently used reference position. As a result, when the amount of deviation between the vanishing point position and the reference position is less than the predetermined amount (step S14: No), the process exits the flow. In this case, the camera unit 20 does not correct the reference position.

  On the other hand, if the amount of deviation between the vanishing point position and the reference position is greater than or equal to the predetermined amount (step S14: Yes), the process proceeds to step S15, and the camera unit 20 determines the reference position based on the vanishing point detected this time. to correct. That is, the camera unit 20 applies the vanishing point detected this time as a new reference position that becomes the center of the vehicle 1. Then, the camera unit 20 stores this new reference position.

  Next, FIG. 7 is a flowchart showing the lane keeping control executed by the controller 8 in the vehicle 1 in the embodiment of the present invention. This flow is repeatedly executed by the controller 8 at a predetermined cycle.

  First, in step S21, the controller 8 determines whether or not the camera unit 20 is correcting the reference position. In one example, when the camera unit 20 corrects the reference position, the camera unit 20 outputs a signal indicating that to the controller 8, and the controller 8 receives the signal when such a signal is input. It is determined that the unit 20 is correcting the reference position.

As a result of the determination in step S21, when it is determined that the camera unit 20 is correcting the reference position (step S21: Yes), the process proceeds to step S22, and the controller 8 performs the yaw angle input from the camera unit 20 with respect to the yaw angle. The gain to be applied (specifically, the gain applied to the yaw angle term determined according to the yaw angle) is reduced, that is, the gain is weakened. Then, the process proceeds to step S23.
On the other hand, as a result of the determination in step S21, if it is not determined that the camera unit 20 is correcting the reference position (step S21: No), the process proceeds to step S23 without performing the process in step S22.

  In step S23, the controller 8 calculates a target position that the vehicle 1 should travel based on the curvature of the clothoid curve, the curvature of the traveling lane, the yaw angle, and the lateral position input from the camera unit 20 (see FIG. 4). . Specifically, the controller 8 first uses a predetermined arithmetic expression defined in advance, for example, a clothoid term corresponding to the clothoid curve, a curvature term corresponding to the curvature of the traveling lane, and a yaw angle corresponding to the yaw angle. A term and a lateral position term corresponding to the lateral position are calculated. Next, the controller 8 multiplies each of the calculated clothoid term, curvature term, yaw angle term, and lateral position term by a predetermined gain. In this case, when the gain value to be applied to the yaw angle term is reduced in step S22, the controller 8 uses the gain value. Then, the controller 8 adds the plurality of values obtained by multiplying the gains in this way, and further multiplies the values obtained by the addition processing by the gains to obtain the target position.

  Next, in step S24, the controller 8 calculates a target yaw rate to be generated in the vehicle 1 in order to cause the vehicle 1 to travel the target position calculated in step S23, and a steering angle (target steering angle) corresponding to the target yaw rate. The self-aligning torque generated in the tire of the vehicle 1 when the above is achieved is calculated. Specifically, the controller 8 calculates a target yaw rate from the target position in accordance with a predetermined time until the vehicle 1 reaches the target position, and the vehicle 1 from the steering angle corresponding to the target yaw rate. The self-aligning torque is calculated from the slip angle.

  Next, in step S25, the target yaw rate to be finally generated from the vehicle 1 (final target yaw rate) by adding the self-aligning torque calculated in step S24 and the target yaw rate obtained from the target position described above. Is calculated.

  Note that the controller 8 calculates the target yaw rate (including the target yaw rate and final target yaw rate according to the target position) and the self-aligning torque in steps S24 and S25, the vehicle speed detected by the vehicle speed sensor 14, and the yaw rate sensor 16. Various sensor values such as the yaw rate detected by the steering angle and the steering angle detected by the steering angle sensor 18 are appropriately used.

  Next, in step S26, the controller 8 obtains a steering assist torque to be applied to the steering shaft 4 from the final target yaw rate so that the vehicle 1 generates the final target yaw rate calculated in step S25. Then, the controller 8 executes control (steering control) on the electric power steering mechanism 6 so that the obtained steering assist torque is applied to the steering shaft 4.

[Function and effect]
Next, the effect of the lane keeping control device according to the embodiment of the present invention will be described.

  As described above, in the lane keeping control device according to the embodiment of the present invention, when the camera unit 20 is correcting the reference position based on the vanishing point, the camera unit 20 is not correcting the reference position. Instead, the target position is calculated by reducing the contribution degree of the parameter obtained from the reference position among the plurality of parameters input from the camera unit 20. Thereby, even when the camera unit 20 is performing the process of correcting the reference position, appropriate lane keeping control can be continued. Specifically, according to the present embodiment, by using the parameter obtained according to the reference position being corrected as it is, it is possible to suppress the appropriate lane keeping control from being performed, In order to prevent this, it is possible to suppress the lane keeping control from being stopped.

  In particular, in the lane keeping control device according to the embodiment of the present invention, when the camera unit 20 corrects the reference position based on the vanishing point, the contribution of the yaw angle obtained from the reference position (with respect to the yaw angle). Therefore, the lane keeping control can be continued more appropriately.

[Modification]
Next, a modification of the above embodiment will be described.

  In the embodiment described above, a plurality of camera units 20 (specifically, microcomputers of the camera unit 20) different from the controller 8 that performs control in the vehicle 1 (for example, control over the electric power steering mechanism 6) are necessary for lane keeping control. Parameters, specifically the curvature of the clothoid curve, the curvature of the traveling lane, the yaw angle and the lateral position. In another example, image data of an image taken in front of the vehicle photographed by the camera is input to the controller 8, and the controller 8 performs image processing (analysis) on the image data, so that a plurality of such A parameter may be obtained. In this example, the controller 8 constitutes a part of the camera unit in the present invention (a part excluding the camera body). In other words, the camera body and the controller 8 constitute a camera unit in the present invention.

  In the above-described embodiment, the target position is obtained when the lane keeping control is performed, that is, the lane keeping control is performed based on the target position. In another example, a travel line (target travel line) that the vehicle should travel to maintain the lane may be obtained, and the lane maintenance control may be performed based on the target travel line. Since this target travel line connects consecutive target positions (in other words, because it is a trajectory of continuous target positions), after all, performing lane keeping control based on the target travel line is It is synonymous with performing lane keeping control based on this.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 Steering wheel 4 Steering shaft 6 Electric power steering mechanism 8 Controller 20 Camera unit

Claims (3)

A lane keeping control device for performing lane keeping control of a vehicle,
Parameter acquisition means for capturing a plurality of parameters from a camera unit that captures a front landscape of the vehicle and obtains a plurality of parameters including at least a vehicle state defined with respect to the traveling lane;
Based on a plurality of parameters acquired by the parameter acquisition means, target position calculation means for calculating a target position to be driven by the vehicle for maintaining the lane;
Target yaw rate calculating means for calculating a target yaw rate to be generated in the vehicle in order to cause the vehicle to travel the target position calculated by the target position calculating means;
Steering control means for performing steering control of the vehicle so as to cause the vehicle to generate the target yaw rate calculated by the target yaw rate calculation means;
Have
The target position calculation means is configured so that the camera unit corrects the reference position of the vehicle based on the vanishing point in the forward scenery, than the case where the camera unit does not correct the reference position. A lane keeping control device, wherein the target position is calculated by reducing a contribution degree of a parameter obtained from the reference position among a plurality of parameters. Of the plurality of parameters, the parameter obtained from the reference position is a yaw angle indicating a direction in which the vehicle is facing the traveling lane,
The target position calculation means reduces the contribution of the yaw angle when the camera unit corrects the reference position compared to when the camera unit does not correct the reference position. The lane keeping control device according to claim 1, wherein the target position is calculated. In addition to the yaw angle, the plurality of parameters include a curvature of the traveling lane, a curvature of a clothoid curve corresponding to the traveling lane, and a lateral position indicating a lateral position of the vehicle in the traveling lane,
When the camera unit is correcting the reference position, the target position calculating means reduces only the contribution of the yaw angle, and reduces the curvature of the traveling lane, the curvature of the clothoid curve, and the horizontal The lane keeping control device according to claim 2, wherein the target position is calculated while maintaining a contribution degree of each position.

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