JP6404609B2 - Steering support control device - Google Patents

Description

  The present invention relates to a technical field of a steering assist control device mounted on an automobile.

JP 2008-68783 A Japanese Patent No. 2812111

  As a steering assist function, a lane keeping function is known in which a vehicle recognizes a lane and continuously supports a steering operation so as to travel in the center. The “lane” means a mark such as a white line (or orange line) that is formed on the road surface and that defines a travel path (lane).

  At present, the steering assist control is designed to stop operation on a sharp curve in consideration of safety. This is realized by setting a condition that the radius of curvature of the curved road on which the vehicle travels is a predetermined value or more as a condition for turning on the steering assist control.

However, by setting the curvature condition of such a curve, the steering assist control is turned off (automatically stopped) according to the approach to the sharp curve while traveling on the so-called winding road where the sharp curve continues. There is a problem that steering assistance control is turned on (returned) again after exiting a sharp curve and steering assistance control is turned off again when entering a sharp curve again (so-called hunting).
When such support control hunting occurs, there is a risk of annoying the driver. In particular, when there is a function of notifying the driver of the automatic stop or return of the assist control by display or sound, it is more troublesome.

  In view of the above, an object of the present invention is to overcome the above-described problems, to prevent the occurrence of hunting in steering assist control while traveling on a winding road, and to reduce the annoyance felt by the driver.

1stly, the steering assistance control apparatus which concerns on this invention is an operation condition determination process part which performs determination about one or several operation conditions including at least the operation condition based on the curvature of a curve road as an operation condition of steering assistance control, Based on the determination result of the operation condition by the operation condition determination processing unit, a steering support control unit that performs steering support control, and determines whether or not the vehicle is traveling on a winding road based on the curvature and continuity of a curved road The steering assist control is performed until a predetermined time elapses from the end of the curved road or the vehicle travels a predetermined distance while it is determined by the winding determination processing unit and the winding determination processing unit that the vehicle is traveling on the winding road. e Bei and suppresses restoration suppression processor to return to the operating state from the stopped state, and the winding determination process unit is within a predetermined time or A winding start determination process for determining whether or not a winding road has started based on a result of determining whether or not a curved road having a radius of curvature less than a predetermined radius of curvature has been detected a predetermined number of times or more within a fixed distance traveling, and the winding start determination After determining that the winding road has started by processing, the winding road is determined based on the result of determining whether a curved road having a radius of curvature less than a predetermined curvature is detected within a predetermined time or within a predetermined distance from the end of the curved road. Winding continuation determination processing for determining whether or not is continuing .

  As a result, while it is determined that the vehicle is traveling on a winding road, the steering assist control does not immediately return to the operating state even when the curved road is finished, and this corresponds to a case where the interval between the sharp curves is short. Thus, it is possible to maintain the return suppression state of the steering assist control until the next sharp curve.

This also makes a determination as to whether or not the vehicle is traveling on a winding road based on the result of actually detecting a curved road.

Second, in the steering assist control device according to the present invention described above, the winding determination processing unit, as the winding start determination processing, detects a past predetermined time starting from a time point when a curve less than the predetermined curvature radius is detected. It is desirable to determine whether or not the winding road has started based on the result of determining whether or not a curved road having a radius of curvature less than the predetermined curvature radius has been detected a predetermined number of times or within a predetermined distance in the past.
Whether or not the winding road has started is determined based on the number of detected curves in the past predetermined time or the predetermined distance traveled regularly regardless of whether or not a curved road having a radius of curvature smaller than the predetermined curvature radius is detected. In this case, the number of detected curves acquired in the past predetermined time or the past predetermined distance traveling and the number of detected curves acquired even while the curved road having a radius less than the predetermined curvature is not detected. It is necessary to perform a comparison / determination process with the predetermined threshold.
On the other hand, if the processing is based on the number of detected curves within the past predetermined time or the past predetermined distance running starting from the time point when the curved road having the predetermined radius of curvature is detected as described above, the predetermined curvature is obtained. Only when a curved road with a radius less than that is detected, it is sufficient to perform the acquisition processing of the number of detected curves within the past predetermined time or the past predetermined distance travel, and the comparison / determination processing between the acquired number of detected curves and a predetermined threshold. It becomes possible to do.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production prevention of the hunting of steering assistance control during driving | running | working on a winding road can be aimed at, and the troublesomeness which a driver | operator feels can be reduced.

It is a block diagram for demonstrating the steering assistance control apparatus of embodiment of this invention. It is a flowchart of a process of the steering assistance control part of embodiment. It is explanatory drawing of the process which the image process part of embodiment performs. It is a flowchart of the operating condition determination process which the image processing part of embodiment performs. It is a summary explanatory drawing of the winding determination process and return suppression process of an embodiment. It is a flowchart of the winding start determination processing of an embodiment. It is a flowchart of the winding continuation determination process of an embodiment. It is a flowchart of the return suppression process of an embodiment.

<1. Configuration of Steering Support Control Device of Embodiment>
Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 shows a main part of an in-vehicle system including the steering assist control device of the embodiment.
The steering assist control device according to the embodiment includes an imaging unit 10 and a steering assist control unit 20. Further, FIG. 1 shows a steering mechanism 30 and a motor drive unit 21 as targets for which the steering support control is performed by this steering support control device. As sensors used for the steering support control, a vehicle speed sensor 15, a yaw rate sensor 16, A lateral acceleration sensor 17 is shown. Further, a display unit 22 and a sound generation unit 23 are shown as related parts of the steering assist control.

The imaging unit 10 includes two imaging units 11 </ b> L and 11 </ b> R and an image processing unit 12 that are installed in a vehicle so as to be able to capture the traveling direction (front).
The imaging units 11L and 11R are arranged at a predetermined interval in the vehicle width direction, for example, in the vicinity of the upper part of the windshield of the host vehicle so that distance measurement by a so-called stereo method is possible. The optical axes of the imaging units 11L and 11R are parallel, and the focal lengths are the same. Also, the frame periods are synchronized and the frame rates are the same. The number of pixels of the image sensor is, for example, about 1280 pixels in the horizontal direction × about 960 pixels in the vertical direction.

  The electrical signals (captured image signals) obtained by the image sensors of the imaging units 11L and 11R are each A / D converted into digital image signals (captured image data) representing luminance values with a predetermined gradation in pixel units. . The captured image data is, for example, color image data. Accordingly, three data (luminance values) of R (red), G (green), and B (blue) are obtained for each pixel. The gradation of the luminance value is, for example, 256 gradations.

The image processing unit 12 includes a microcomputer having, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) as a work area, and various types of programs according to programs stored in the ROM. Execute the process.
The image processing unit 12 stores each frame image data as captured image data obtained by the imaging units 11L and 11R imaging the front of the host vehicle in the internal memory. Then, based on the two captured image data as each frame, various processes for recognizing an object existing in front of the vehicle as an external environment are executed. For example, a lane, a preceding vehicle, a three-dimensional object such as an obstacle, and the like are recognized. These processes will be described later.

Image recognition results such as a three-dimensional object and a lane by the image processing unit 12 are used for various driving support controls. For example, inter-vehicle distance control and collision avoidance control.
Regarding the steering assist control of the present embodiment, detected lane data (including the own vehicle traveling path, etc.), side walls data such as guardrails, curbs, etc. existing along the road, and solid object data (type, distance, Each data such as speed, relative speed with respect to the host vehicle, and preceding vehicle information is input to the steering assist control unit 20.
Further, the image processing unit 12 also determines the operating condition of the steering assist control as will be described later, and supplies the determination result to the steering assist control unit 20.

  The steering support control unit 20 performs steering support such as automatic steering control based on the above-described input data. That is, the steering assist control unit 20 maintains the host vehicle in the center of the host vehicle traveling path by setting the steering angle independently of the driver (driver) based on the lane ahead of the host vehicle, for example. It is possible to perform steering support such as lane keeping control and lane departure control for preventing deviation of the own vehicle from the own vehicle route (deviation of the own vehicle with respect to the white line defining the own vehicle traveling route).

  The steering assist control unit 20 determines operating conditions of various types of steering assist control, and executes the steering assist control when the operating conditions are satisfied. Whether or not the steering assist control is operable is performed based on the operation information SD of the driver, information from the image processing unit 12, information from each sensor, and the like. Details will be described later. Here, the operation information SD of the driver comprehensively indicates operation information such as an on / off operation of an ACC (Adaptive Cruise Control) switch or a steering assist execution switch.

  For example, a vehicle speed sensor 15 that detects a vehicle speed, a yaw rate sensor 16 that detects a yaw rate, a lateral acceleration sensor 17 that detects a lateral acceleration, and the like are connected to the steering assist control unit 20 and the image processing unit 12.

For example, the steering mechanism 30 that is a target of the steering assist control is configured as follows. In this example, the steering mechanism 30 is shown as an electric power steering device in which the steering angle can be set independently of the driver input.
In the steering mechanism 30, a steering shaft 32 is rotatably supported on a body frame (not shown) via a steering column 33. One end of the steering shaft 32 extends toward the driver's seat, and a steering wheel 34 is attached to one end of the steering shaft 32. The other end of the steering shaft 32 extends to the engine room side, and a pinion shaft 35 is connected to the other end of the steering shaft 32.
A steering gear box 36 extending in the vehicle width direction is disposed in the engine room, and a rack shaft 37 is inserted into and supported by the steering gear box 36 so as to be reciprocally movable. A rack (not shown) is provided in the middle of the rack shaft 37, and a rackion and pinion type steering gear mechanism is formed by engaging a pinion (not shown) provided on the pinion shaft 35 with the rack. It is configured.

  Further, both left and right ends of the rack shaft 37 protrude from the steering gear box 36, and a front knuckle 39 is connected to the end of the rack shaft 37 via a tie rod 38. The front knuckle 39 rotatably supports left and right wheels 40L and 40R as steering wheels, and is supported by a vehicle body frame via a king pin (not shown) so as to be continuously hit. Accordingly, when the steering wheel 34 is operated to rotate the steering shaft 32 and the pinion shaft 35, the rack shaft 37 moves in the left-right direction by the rotation of the pinion shaft 35, and the front knuckle 39 is moved to the king pin (not shown). And the left and right wheels 40L, 40R are steered in the left-right direction.

  An electric motor 42 is connected to the pinion shaft 35 via an assist transmission mechanism 41. The electric motor 42 assists the steering torque applied to the steering wheel 34 and provides a set steering angle. Such a steering torque is added. The electric motor 42 is driven via the motor drive unit 21 so as to have a steering torque (control amount) set by the steering assist control unit 20.

Steering support control includes such steering torque assistance, but also provides warnings about lane departure on the road and notifications regarding steering assistance. Therefore, as shown in the figure, the steering assist control unit 20 supplies display information and sound generation instruction information to the display unit 22 and the sound generation unit 23.
The display unit 22 comprehensively shows, for example, a display control unit and a display device using a microcomputer. The display device is, for example, various meters such as a speedometer and a tachometer provided in a meter panel installed in front of the driver, MFD (Multi Function Display), and other devices for presenting information to the driver. With respect to the steering assist control, the display unit 22 performs a warning display or a display for presenting the driver with the operation support / stop of the steering assist.
The sound generation unit 23 comprehensively shows a sound generation control unit such as a microcomputer and a sound generation device such as an amplifier / speaker. The sound generation unit 23 outputs a warning sound and a notification sound for notifying the driver of the operation / stop of the steering support regarding the steering support control.

FIG. 2 shows a steering assist operation condition process of the steering assist controller 20. The steering assist control unit 20 determines the operation / stop of the steering assist control by the processing of FIG.
First, in step S101, the steering assist control unit 20 confirms whether or not ACC is turned on by the operation information SD, that is, whether or not a driver assist mode is instructed.
Next, in step S102, the steering support control unit 20 confirms whether or not the steering support is turned on by the operation information SD, that is, whether or not the driver is instructed to perform the steering support.

Further, the steering assist control unit 20 confirms whether or not the vehicle speed condition is OK in step S103. For example, the steering assist control is set to operate when the vehicle speed is equal to or higher than a certain speed (for example, when 65 km / h or higher). The steering assist control unit 20 determines from the information of the vehicle speed sensor 15 whether or not the vehicle is currently at a certain speed or higher. Note that the image processing unit 12 may determine the vehicle speed condition from the information of the vehicle speed sensor 15 and the steering assist control unit 20 may confirm the determination result.
Subsequently, in step S104, the steering assist control unit 20 confirms whether or not the lateral acceleration condition is OK. For example, the steering assist control is set to operate when the lateral acceleration is within a certain range (for example, within 2.0 G). The steering assist control unit 20 determines from the information of the lateral acceleration sensor 17 whether or not the current lateral acceleration is within a certain range. Alternatively, the image processing unit 12 may determine the lateral acceleration condition from the information of the lateral acceleration sensor 17, and the steering assist control unit 20 may confirm the determination result.

Further, in step S105, the steering assist control unit 20 confirms whether or not the travel path related condition is OK. In this example, the process refers to the determination result of the travel route related condition from the image processing unit 12. The “traveling road-related condition” here is used as a comprehensive term for the following conditions.
-Lane recognition conditions: Lanes can be recognized by image processing.
-Curvature condition: The curvature of the curved road on which the vehicle is traveling is within a certain range.
Road width condition: The road width is within a predetermined range (for example, 3 m or more and less than 4 m).
Non-recovery suppression condition: The return suppression flag is not set to ON by the return suppression process described later with reference to FIG. 8 (it is not determined that the vehicle is traveling on the winding path by the winding determination process described later, or the winding path) Even if it is determined that the vehicle is traveling, a predetermined time has passed since the end of the curved road (or the vehicle has traveled a predetermined distance).

  When the image processing unit 12 determines that the lane recognition condition, the curvature condition, the road width condition, and the non-return-suppressing condition are all satisfied and can be operated, the image processing unit 12 transmits information on the travel path related condition OK (travel path related condition satisfaction). Come on. On the other hand, when any one of the conditions is not satisfied, information indicating a travel route related condition NG (travel route related condition not satisfied) is transmitted. The steering assist control unit 20 confirms such travel path related condition information in step S105.

  The steering support control unit 20 determines that the steering support operation is performed in step S106 and executes the steering support control only when an OK (condition satisfaction) result is obtained in all of steps S101 to S105. On the other hand, if it becomes NG (condition not satisfied) in any of steps S101 to S105, it is determined in step S107 that the steering support is stopped, and the steering support control is stopped.

<2. Processing of Image Processing Unit of Embodiment>
FIG. 3 is an explanatory diagram of processing executed by the image processing unit 12, and shows various types of processing executed by the image processing unit 12 in blocks for each function. As shown in the figure, the image processing unit 12 is roughly classified by function, and the three-dimensional position information generation processing unit 30, the lane detection processing unit 31, the lane model formation processing unit 32, the preceding vehicle detection processing unit 33, the operating condition determination processing. Unit 34, a winding determination processing unit 35, and a return suppression processing unit 36.

The three-dimensional position information generation processing executed by the three-dimensional position information generation processing unit 30 is based on two left and right captured image data (that is, a pair of captured image data captured in stereo) stored in the internal memory. It is a process to generate. Specifically, in the three-dimensional position information generation processing, corresponding points between a pair of captured image data are detected by pattern matching, a coordinate shift between the detected corresponding points is calculated as a parallax dp, and the parallax dp is used. This is a process of generating the information of the position of the corresponding point in the real space as the three-dimensional position information by the principle of triangulation.
In calculating the coordinate deviation as the parallax dp as described above, one of the pair of captured image data is determined in advance as a “reference image” and the other as a “comparison image”. The comparison image is generated as an image having a larger number of pixels in the horizontal direction than the reference image in order to allow the calculation of the parallax dp for the object located at the horizontal end on the reference image.

Here, the three-dimensional position information includes a point directly below the center of the pair of cameras (imaging units 11L and 11R) as an origin, an X axis in the direction connecting the pair of cameras, a Y axis in the vertical direction, and a Z axis in the front and rear direction. This is information represented as a point (X, Y, Z) on the space when taken.
The respective values of X, Y, and Z as the three-dimensional position information are expressed as pixel coordinates (i, j) when the axis parallel to the horizontal direction in the reference image is i-axis and the axis parallel to the vertical direction is j-axis. ), The distance between the pair of cameras is CD, the viewing angle per pixel is PW, the mounting height of the pair of cameras is CH, and the i-coordinate and j-coordinate on the reference image at the infinity point in front of the camera are When IV and JV are set, they are obtained by coordinate transformation represented by the following [Formula 1] to [Formula 3].
X = CD / 2 + Z × PW × (i-IV) [Formula 1]
Y = CH + Z × PW × (j−JV) [Formula 2]
Z = CD / {PW × (dp−DP)} [Formula 3]
“DP” in [Expression 3] is also referred to as a vanishing point parallax, an infinite distance corresponding point, or the like, but in short, the parallax dp between corresponding points between the reference image and the comparison image, and in the real space up to the corresponding point Is a value determined so as to satisfy the above [Equation 3]. Hereinafter, this “DP” is expressed as “parallax offset value DP”.

  The lane detection process executed by the lane detection processing unit 31 is based on the reference image and the three-dimensional position information (including the distance Z for each pixel as a corresponding point) generated by the above-described three-dimensional position information generation process. This is processing for detecting a lane formed on the road surface on which the host vehicle travels. In the lane detection process, since the lane is brighter than the road surface, the luminance change of the pixels in the width direction of the road is evaluated to detect the positions of the left and right lane candidate points on the road surface. At this time, the position of the lane candidate point is detected as a position (X, Y, Z) in the three-dimensional space.

  The lane model formation process executed by the lane model formation processing unit 32 is a process for forming a lane model in a three-dimensional space based on the lane candidate points detected by the lane detection process. Specifically, a lane model in a three-dimensional space is formed by approximating lane candidate points detected for each row (each horizontal line) in the lane detection processing by, for example, the least square method. With the lane model formed in this way, the height information of the road surface on which the host vehicle travels can also be obtained.

The preceding vehicle detection process executed by the preceding vehicle detection processing unit 33 is a process for detecting a preceding vehicle existing ahead of the host vehicle based on the reference image and the three-dimensional position information. In the preceding vehicle detection process, first, an object detection process is performed based on the three-dimensional position information, and an object present in the image is detected including information on the distance Z to the object. For example, in this object detection process, a distance image is generated in which each corresponding point detected in the previous parallax dp calculation process is associated with the value of the distance Z on the image, and the distance image is partitioned in the vertical direction. Divide into multiple vertical areas, create a distance histogram that represents the distance distribution in the vertical direction of the image (j direction) for each vertical area, and the distance Z (corresponding point) where the frequency is maximum exists in that vertical area This is the representative distance of the target object. Then, for each corresponding point having the maximum frequency for which the representative distance is obtained, pixel ranges that are regarded as the same object are grouped from the relationship such as the distance Z and direction to each adjacent corresponding point, and exist in the image. Specify the range of each object. Thereby, an object existing in the image is detected including information on the distance Z to the object.
Here, the distance image is obtained sequentially for each frame. In the preceding vehicle detection process, by monitoring the information of the distance Z of the detected object over a plurality of frames, an object that exists on the traveling path of the own vehicle and moves at a predetermined speed in substantially the same direction as the own vehicle. Extract as a preceding vehicle. At this time, in order to suppress erroneous detection of an object other than the vehicle, pattern matching using the reference image (for example, pattern matching based on a feature point of the vehicle such as a brake lamp portion) is also performed.
When the preceding vehicle is detected, the preceding vehicle detection information includes the preceding vehicle distance (= inter-vehicle distance), the preceding vehicle speed (= change ratio of the inter-vehicle distance + own vehicle speed), and the preceding vehicle acceleration (= differential of the preceding vehicle speed). Value).
Note that the method of the preceding vehicle detection process is the same as the method disclosed in Japanese Patent Application Laid-Open No. 2012-66759. For details, refer to this document.

  Note that the image processing unit 12 also detects three-dimensional objects (side walls, guardrails, obstacles, etc.) other than the preceding vehicle based on the object information detected by the object detection process. The image processing unit 12 compares the data on the distance image with frames (windows) such as three-dimensional side wall data and three-dimensional object data stored in advance, and a guardrail and curb extending along the road The three-dimensional object is classified and detected as another three-dimensional object such as a bicycle, a two-wheeled vehicle, a pedestrian, or a utility pole. In the detection of the three-dimensional object, the image processing unit 12 calculates a relative speed with respect to the own vehicle from the rate of temporal change in the distance (relative distance) to each own vehicle, and adds the relative speed and the own vehicle speed. Thus, the speed of each three-dimensional object is calculated. At this time, the three-dimensional object classified as a vehicle has a forward direction of the own vehicle as positive from the speed, a vehicle having a speed of approximately 0 is a stopped vehicle, and a speed is positive (a vehicle traveling in the same direction as the own vehicle). A vehicle closest to the host vehicle is recognized as a preceding vehicle, and a vehicle with a negative speed (a vehicle coming toward the host vehicle) is recognized as an oncoming vehicle.

  The operation condition determination process executed by the operation condition determination processing unit 34 determines the above-described “travel path related condition” as the steering assist control operation condition, and steers the travel path related condition information according to the determination result. This is a process of outputting to the support control unit 20.

FIG. 4 is a flowchart of the operating condition determination process executed by the image processing unit 12. This operation condition determination process is executed as an operation condition determination for steering assist control at each frame timing at which captured image data is obtained or at each intermittent frame timing, for example.
First, in step S201, the image processing unit 12 determines the lane recognition condition described above. Specifically, the lane model formation processing unit 32 determines whether left and right lane models are formed. If the left and right lane models are not formed and the lane cannot be recognized, steering assistance is not performed in the first place. Therefore, in step S206, the driving road related condition information NG as the driving road related condition NG is obtained. Output to.

On the other hand, when the lane can be recognized, the image processing unit 12 performs the following.
That is, in the steps S202 and S203, the above-described curvature condition and road width condition are determined. In the curvature condition determination in step S202, for example, using the detection information of the yaw rate sensor 16 and the vehicle speed sensor 15, the curvature radius of the traveling path of the host vehicle is calculated, and the calculated curvature radius is the curvature radius allowed for the steering assist control. This is done by determining whether or not there is. The curvature radius information used in the curvature condition determination may be calculated as the curvature radius of the curve of the traveling path (lane) recognized on the captured image.
In the road width condition determination in step S203, for example, the road width, that is, the width between the left and right lanes is calculated from the captured image data, and it is determined whether or not the road width is allowed for the steering assist control.
If either the curvature condition or the road width condition is NG, the image processing unit 12 outputs the travel path related condition information called the travel path related condition NG to the steering assist control unit 20 in step S206. That is, in this case, the steering assist control does not operate.

In step S204, the image processing unit 12 confirms whether the return is being suppressed. Whether or not the return is being suppressed is determined by determining whether or not a return suppression flag described later is in an ON state. Even if all of the lane recognition condition, the curvature condition, and the road width condition are OK, if the return is being suppressed, the road-related condition information called the road-related condition NG is output to the steering assist control unit 20 in step S206.
The image processing unit 12 proceeds from step S204 to S205 only when the lane recognition condition, the curvature condition, and the road width condition are all OK and the return is not being suppressed, and the travel path related condition information OK as the travel path related condition OK. This is output to the steering assist control unit 20. In response to this, the steering assist control is activated (or the operational state is maintained).

Returning to FIG. 3, the winding determination processing executed by the winding determination processing unit 35 is a process for determining whether or not the vehicle is traveling on the winding road based on the curvature and continuity of the curved road.
In this example, the winding determination process includes a winding start determination process that determines whether or not the winding path has started, and a winding continuation determination process that determines whether or not the winding path is continuing after the winding path has started. Become. In FIG. 3, functional blocks corresponding to the winding start determination process and the winding continuation determination process of the image processing unit 12 are shown as a winding start determination processing unit 35a and a winding continuation determination processing unit 35b, respectively.

  In addition, the return suppression process executed by the return suppression processing unit 36 passes a predetermined distance or a predetermined distance from the end of the curved road while it is determined that the vehicle is traveling on the winding road by the winding determination process. This is a process of suppressing the steering assist control from returning from the stopped state to the operating state.

The outline of the winding determination process and the return suppression process will be described with reference to FIG. Note that the shaded portion in FIG. 5 schematically represents the road on which the host vehicle travels. In this case, it is assumed that the host vehicle is traveling from the left side to the right side.
First, as a winding start determination process, whether or not a winding road has started is determined based on whether or not a curved road having a radius of curvature less than a predetermined curvature has been detected a predetermined number of times within a predetermined time or within a predetermined distance. Judgment based on. In the winding start determination process of this example, it is determined whether or not a curved road having a radius less than the predetermined curvature has been detected, for example, three or more times within the past predetermined time from the time when a curved road having a radius less than the predetermined curvature is detected. The result is a determination result of whether or not the winding path has started.
FIG. 5 shows an example in which the start of the winding path is determined at the time point t1 in the drawing by the above-described winding start determination process.

In the winding continuation determination process, a predetermined radius of curvature within a predetermined time or within a predetermined distance from the end of the curve road after the winding start determination process determines that the winding road has started or not after it has been determined by the winding start determination process. It judges based on the result of having discriminate | determined whether the less curved road was detected. In the winding continuation determination process of this example, whether or not the winding road is continuing is determined based on whether or not a curved road having a radius of curvature less than the predetermined curvature is detected within 15 seconds from the end of the curve road having a radius of curvature less than the predetermined radius. It is determined as a result of the determination.
In FIG. 5, after the start of the winding road is determined, three curved roads having a radius of curvature less than a predetermined curvature radius are continuously connected at a relatively short interval, and thereafter, after a curved road having a radius of curvature greater than or equal to the predetermined curvature radius, the curve road is relatively long. An example in which a straight road exists is shown. In such a case, depending on the above-described winding continuation determination process, a predetermined curvature after time t2 when a curved road less than a predetermined curvature radius is detected again after time t1 when the start of the winding road is determined and after time t2. A determination result that the winding road is continuing is obtained at time t3 when the curved road having a radius less than the radius is detected again and at time t4 when the curved road having the radius of curvature less than the predetermined curvature is detected again after time t3. In this case, since a curved road having a radius less than the predetermined curvature is not detected within a predetermined time after the time t4, it is determined that the winding road is not continuing at the time t5 when the predetermined time has elapsed from the time t4. A result is obtained (that is, it is determined that the winding path is finished).

Depending on the return suppression process, a predetermined time elapses or travels a predetermined distance from the end of the curved road between time t1 and time t4 when it is determined that the winding road is continuing (traveling on the winding road). Until the steering assist control is returned to the operating state. In the return suppression process of this example, the return suppression of the steering assist control is performed until, for example, 15 seconds elapses from the end of the curved road having a radius less than the predetermined curvature radius.
In the example of FIG. 5, the steering assist is performed between the curved roads corresponding to the time points t1 and t2, the curved roads corresponding to the time points t2 and t3, and the curved roads corresponding to the time points t3 and t4. Control return suppression is performed. Further, the return of the steering assist control is suppressed for 15 seconds after the curve road at the time point t4 ends. As described above, since a curved road having a radius of curvature less than the predetermined curvature radius is not detected within a predetermined time (within 15 seconds) after time t4, it is determined that the winding road is not continuing at time t5. For this reason, after the return suppression for 15 seconds from the end of the curved road corresponding to the time point t4 is performed, the other lane recognition conditions such as the lane recognition conditions and the road width conditions described above and those shown in FIG. If the various operation conditions other than are satisfied, the steering assist control is activated.

Here, in order to prevent the return suppression from ending during the determination that the winding path is continuing, “predetermined time” (hereinafter referred to as “predetermined time T1”) used in the winding continuation determination process is used. The “predetermined time” (hereinafter referred to as “predetermined time T2”) used in the return suppression process may be “T2 ≧ T1”. In the winding continuation determination process, the detection condition for a curved road having a radius of curvature less than a predetermined curvature radius is set to “within a predetermined distance travel”, and the period for performing the return suppression in the return control process is “from the end of the curved road until the vehicle travels a predetermined distance”. For the same purpose, “predetermined distance” used in the winding continuation determination process (hereinafter referred to as “predetermined distance D1”) and “predetermined distance” used in the return suppression process (hereinafter referred to as “predetermined distance D2”). May be set as “D2 ≧ D1”. In this case, as the “predetermined distance D1”, for example, a value corresponding to a distance assumed as the length of a substantially straight section (a section connecting curves less than a predetermined curvature radius) on the winding path may be set.
Needless to say, “T2 ≦ T1” and “D2 ≦ D1” may be set. The term “preventing hunting” as used herein means preventing the steering assist control from being stopped / actuated repeatedly in a relatively short cycle, and is not necessarily suppressed during the determination that the winding path is continuing. It is not indispensable to prevent from being terminated.

<3. Processing procedure>
Hereinafter, with reference to the flowcharts of FIGS. 6 to 8, a description will be given of specific processing procedures to be executed in order to realize the functions described as the winding determination process and the return suppression process.

FIG. 6 is a flowchart of the winding start determination process.
In FIG. 6, the image processing unit 12 waits until it detects a curved road having a radius of curvature less than a predetermined curvature in step S <b> 301. Specifically, the curvature radius of the traveling path of the host vehicle is sequentially calculated using detection information of the yaw rate sensor 16 and the vehicle speed sensor 15, and the system waits until the calculated curvature radius becomes less than a predetermined value.

When a curved road having a radius of curvature less than the predetermined curvature radius is detected, the image processing unit 12 determines whether or not the winding flag is OFF in step S302. The winding flag is an identifier managed by the image processing unit 12 to identify whether or not the host vehicle is traveling on the winding road. The winding flag = ON indicates that the vehicle is traveling on the winding road. The winding flag = OFF indicates that the vehicle is not traveling on the winding road.
If the winding flag is not OFF, the image processing unit 12 ends the process shown in FIG. That is, since it is determined that the vehicle is traveling on the winding road (that is, after the start of the winding road is determined), the winding continuation determination process should be executed instead of the winding start determination process shown in FIG. Steps S303 to S306 described below are passed, and the process ends.

  If the winding flag is OFF, the image processing unit 12 stores information on the detection time of the curved road in step S303, that is, information on the time when the curved road detected in step S301 is detected (current time information may be stored) in, for example, an internal memory. In subsequent step S304, information on the number n of detected curves in the past predetermined time is acquired. That is, among the detection times stored in the process of step S303 performed in the past, the number of time information representing the time within the past predetermined time is acquired as the information of the detection curve number n.

Further, in step S305, the image processing unit 12 determines whether or not the acquired number of detected curves n is equal to or greater than the curve number threshold THc (“3” described above in this example). If the detected curve number n is equal to or greater than the curve number threshold THc, the curve road having the radius of curvature less than the predetermined curvature radius has been detected a predetermined number of times within the past predetermined time from the time point when the curve road having the radius of curvature less than the predetermined radius is detected. That is, the winding start condition in this example is satisfied. Therefore, in this case, the image processing unit 12 turns on the winding flag in step S306, and ends the processing shown in this figure.
On the other hand, if the detected curve number n is not equal to or greater than the curve number threshold value THc, the winding start condition of this example is not satisfied, so the image processing unit 12 passes step S306 and ends the process shown in this figure.

FIG. 7 is a flowchart of the winding continuation determination process.
First, in step S401, the image processing unit 12 waits for an end point of a curved road having a radius less than a predetermined curvature. That is, it waits until an end point of a curved road having a radius less than a predetermined curvature radius is detected based on information on the curvature radius of the traveling path of the host vehicle that is sequentially calculated using detection information of the yaw rate sensor 16 and the vehicle speed sensor 15. .

  When the end point of the curved road having a radius of curvature less than the predetermined curvature radius is detected, the image processing unit 12 determines whether or not the winding flag is ON in step S402. If the winding flag is not ON, the following description will be given. Steps S403 to S407 to be executed are passed and the processing shown in FIG. That is, the winding continuation determination process in FIG. 7 is to be executed in response to a case where the vehicle is traveling on the winding road. Therefore, if the winding flag is not ON, the process ends.

On the other hand, when the winding flag is ON, the image processing unit 12 starts time counting in step S403, and detects a curved road having a radius of curvature less than a predetermined curvature radius by the processing in steps S404 and S405, or a predetermined time ( Wait until any condition that the predetermined time T1) elapses is satisfied.
The fact that a curved road less than the predetermined curvature radius is detected in step S404 means that a curved road less than the predetermined curvature radius is detected within a predetermined time from the end of the curved road less than the predetermined curvature radius. The example winding continuation condition will be satisfied. Therefore, when a curved road having a radius of curvature less than the predetermined curvature radius is detected in step S404, the image processing unit 12 resets the time count in step S407 and ends the processing shown in this figure. That is, in this case, the winding flag is maintained in the ON state.

  On the other hand, if it is determined in step S405 that the predetermined time has elapsed, the winding continuation condition of this example is not satisfied. In this case, the image processing unit 12 proceeds to step S406, turns off the winding flag, resets the time count in step S407, and ends the processing shown in this figure.

FIG. 8 is a flowchart of the return suppression process.
In FIG. 8, the image processing unit 12 waits for the end of the curved road in step S501. Specifically, the end point of a curved road having a radius less than a predetermined curvature radius is detected based on information on the curvature radius of the traveling path of the host vehicle that is sequentially calculated using the detection information of the yaw rate sensor 16 and the vehicle speed sensor 15. Wait until.

  If the end point of the curved road is detected in step S501, the image processing unit 12 determines whether or not the winding flag is ON in step S502. If the winding flag is not ON, the processing shown in FIG. Finish. That is, when it is determined that the vehicle is not traveling in the winding, the return suppression flag described later is not turned ON, and the return of the steering assist control is suppressed until a predetermined time has elapsed from the end of the curve. Return suppression is not performed.

  For confirmation, if the return suppression flag is OFF, it is determined in step S204 in FIG. 4 that the return is not being suppressed, so that other operating conditions (travel path related conditions) in steps S201 to S203 are determined. ) Is satisfied, since the OK information is output to the steering assist control unit 20 as the travel path related condition information in step S205, it is determined that the travel path related condition is OK in step S105 of FIG. That is, if other operating conditions of steps S101 to S104 are satisfied, the steering assist control is set to the operating state in step S106.

  On the other hand, when the winding flag is ON, the image processing unit 12 sets the return suppression flag to ON in step S503. The return suppression flag is an identifier managed by the image processing unit 12 to identify whether or not the return suppression is performed. The return suppression flag = ON indicates that the return suppression should be performed, and the return suppression flag = OFF indicates the return suppression. Represents that it should not be performed.

In subsequent step S504, the image processing unit 12 starts time counting and waits until a predetermined time elapses in step S505. If the predetermined time has elapsed, the image processing unit 12 turns off the return suppression flag in step S506, resets the time count in step S507, and ends the processing shown in FIG.
As a result, while it is determined by the winding determination process that the vehicle is traveling on the winding road, the return suppression flag is turned on until a predetermined time has elapsed from the end of the curved road, and the return of the steering assist control is suppressed. The That is, even if other operation conditions are satisfied, the travel support related condition information as the travel path related condition NG is supplied to the steering support control unit 20, so that the steering support control does not operate.

<4. Summary of Embodiment>
As described above, the steering assist control device according to the present embodiment has an operation condition determination processing unit that performs determination on one or more operation conditions including at least an operation condition based on the curvature of a curved road as an operation condition of the steering assist control ( The operation condition determination processing unit 34 and the steering assist control unit 20 include the processing in FIG.
Moreover, the steering assistance control part (20) which performs steering assistance control based on the determination result of the operating condition by the operating condition determination process part is provided.
Further, the winding determination processing unit (35) for determining whether or not the vehicle is traveling on the winding road based on the curvature and continuity of the curved road, and the winding determination processing unit determines that the vehicle is traveling on the winding road. And a return suppression processing unit (36) that suppresses the return of the steering assist control from the stopped state to the operating state until a predetermined time has elapsed or the vehicle has traveled a predetermined distance from the end of the curved road.

As a result, while it is determined that the vehicle is traveling on the winding road, the steering assist control does not immediately return to the operating state even when the curved road is finished, and the arrangement interval of the sharp curve is short (hunting In the case where there is a high possibility of the occurrence of the steering assist control, the return suppression state of the steering assist control can be maintained until the next sharp curve.
Accordingly, it is possible to prevent the occurrence of hunting in the steering assist control while traveling on the winding road, and it is possible to reduce the troublesomeness felt by the driver.

In the steering assist control device of the present embodiment, the winding determination processing unit determines whether or not a curved road having a radius less than a predetermined curvature has been detected a predetermined number of times within a predetermined time or within a predetermined distance of traveling. After determining that the winding path has started by the winding start determination process (the process of FIG. 6 by the winding start determination processing unit 35a) for determining whether the winding path has started or not based on Winding continuation determination process for determining whether or not a winding road is continuing based on a result of determining whether or not a curved road having a radius of curvature less than a predetermined curvature is detected within a predetermined time or within a predetermined distance from the end of the road ( 7 is executed by the winding continuation determination processing unit 35b.
As a result, whether or not the vehicle is traveling on the winding road is determined based on the result of actually detecting the curved road.
Therefore, it is possible to increase the reliability of the determination as to whether or not the vehicle is traveling on the winding road.
For example, whether or not the vehicle is traveling on a winding road is determined based on the curvature and continuity of the curved road on the road that the vehicle is expected to pass by using the map information of the car navigation system. Although it is also possible to set a winding road section in advance and determine whether or not the vehicle has reached the winding road section, the method using the car navigation system in this way, for example, a mountain road or the like In this case, it may be difficult to detect the position of the vehicle, and it may be difficult to ensure the reliability of the determination as to whether or not the vehicle is traveling on a winding road. On the other hand, according to the method for determining whether or not the vehicle is traveling on the winding road based on the result of actually detecting the curved road as described above, the reliability of the determination can be further increased.

Furthermore, in the steering assist control device of the present embodiment, the winding determination processing unit travels within the past predetermined time or the past predetermined distance starting from the time point when the curve less than the predetermined curvature radius is detected as the winding start determination processing. Whether or not the winding road has started is determined based on the result of determining whether or not a curved road having a radius of curvature less than the predetermined curvature has been detected a predetermined number of times.
Whether or not the winding road has started is determined based on the number of detected curves within a predetermined period of time (or within a predetermined distance of travel) regardless of whether or not a curved road having a radius of curvature less than a predetermined radius is detected. In this case, the number of detected curves within the past predetermined time (or within the past predetermined distance travel) is acquired and acquired while a curved road having a radius less than the predetermined curvature is not detected. It is necessary to perform a comparison / determination process between the number of detected curves and the predetermined threshold value.
On the other hand, if the processing is based on the number of detected curves within the past predetermined time (or within the past predetermined distance travel) starting from the time point when the curved road having a radius less than the predetermined curvature is detected as described above, As shown in FIG. 6, only when a curved road having a radius of curvature less than a predetermined curvature radius is detected, the number of detected curves within the past predetermined time (or within the past predetermined distance travel) is acquired (S304), and the acquired detection is performed. The comparison / determination process (S305) between the number of curves and the predetermined threshold can be performed.
Therefore, the processing load can be reduced.

<5. Modification>
The present invention is not limited to the specific examples described above, and various modifications can be considered.
For example, in the above, the case where the image processing unit 12 performs part of the operation condition determination process, the winding determination process, and the return suppression process according to the present invention has been illustrated, but the execution subject of these processes is the image processing unit 12. It goes without saying that it is not limited.

In addition, in the above, as the operation conditions other than the operation conditions related to the return suppression (running on the winding road, within a predetermined time or within a predetermined distance from the end of the curve road), the curvature condition, the road width condition, the operation condition (ACC on, Steering support ON), vehicle speed conditions, and lateral acceleration conditions are listed. Of these, conditions other than the curvature condition are merely examples, and not all of these conditions are necessary, and there may be other operating conditions. Good.
Further, the curvature condition, the operation condition, the vehicle speed condition, and the lateral acceleration condition may be determined by the image processing unit 12, the steering assist control unit 20, or another part. It is only necessary that the steering assist control unit 20 finally performs the steering assist control reflecting the determination result.

  DESCRIPTION OF SYMBOLS 10 ... Imaging unit, 11L, 11R ... Imaging part, 12 ... Image processing part, 15 ... Vehicle speed sensor, 16 ... Yaw rate sensor, 17 ... Lateral acceleration sensor, 20 ... Steering control part, 21 ... Motor drive part, 30 ... Steering mechanism

Claims (2)

An operation condition determination processing unit configured to determine one or more operation conditions including at least an operation condition based on a curvature of a curved road as an operation condition of the steering assist control;
A steering support control unit that performs steering support control based on the determination result of the operation condition by the operation condition determination processing unit;
A winding determination processing unit for determining whether or not the vehicle is traveling on the winding road based on the curvature and continuity of the curved road;
While the winding determination processing unit determines that the vehicle is traveling on the winding road, the steering assist control is returned from the stopped state to the operating state until a predetermined time has elapsed from the end of the curved road or the vehicle has traveled a predetermined distance. Bei example and suppresses restoration suppression processor to, a,
The winding determination processing unit
A winding start determination process for determining whether or not a winding road has started based on a result of determining whether or not a curved road having a radius of curvature less than a predetermined radius of curvature has been detected a predetermined number of times within a predetermined time or within a predetermined distance of traveling;
As a result of determining whether or not a curved road having a radius of curvature less than a predetermined radius is detected within a predetermined time or within a predetermined distance from the end of the curved road after determining that the winding road has started by the winding start determination process. And a steering continuation determination process for determining whether or not the winding road is continuing . The winding determination processing unit, as the winding start determination process,
As a result of determining whether or not a curved road less than the predetermined curvature radius has been detected a predetermined number of times within the past predetermined time or the past predetermined distance running from the time when the curve less than the predetermined curvature radius is detected. To determine if the winding path has started
The steering assist control device according to claim 1 .

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