JP6535561B2 - Vehicle travel control device - Google Patents

Description

  The present invention relates to a travel control device for a vehicle that acquires lane information with high accuracy and performs travel control.

  In recent years, various vehicles have been developed and proposed using automatic driving techniques (for example, lane keeping control and lane departure prevention control) so that the driver can drive more comfortably and safely. In such a technology, road parameters used for control are detected and acquired by a camera, a radar, a navigation system or the like. For example, in Japanese Patent Application Laid-Open No. 2005-346304 (hereinafter referred to as Patent Document 1), the image information of the lane in which the host vehicle is traveling is acquired, the traveling lane is recognized by image processing, and the curvature or curve of the traveling lane In a road parameter calculation device for obtaining a radius, there is disclosed a technique of limiting a temporal change rate of a determined road curvature or a curve radius to a predetermined limit value or less and outputting it as a calculation result.

JP, 2005-346304, A

  That is, in lane keeping control or the like in which a lane marking is recognized by a camera and steering control is performed, if a road parameter such as a lane marking is erroneously recognized, control is performed based on the erroneously recognized lane marking. Unfavorable cause of deviation. Therefore, as in the road parameter calculation device disclosed in Patent Document 1 described above, such a phenomenon can be prevented by limiting the temporal change rate of the determined road curvature or curve radius to a predetermined limit value or less. I have to. However, as described in Patent Document 1 described above, when road parameters are limited, there is a problem that the response of turning at high vehicle speeds and the performance of in-lane correction steering can not be ensured, and the lane keeping operation range is limited.

  The present invention has been made in view of the above circumstances, and provides a vehicle travel control device capable of reliably performing control such as lane keeping control and departure prevention control with high accuracy without limiting road parameters more than necessary. It is intended to be provided.

One aspect of a travel control device of a vehicle according to the present invention acquires lane information of a traveling lane, and a travel control device of a vehicle that performs steering control based on the lane information includes the first lane information based on image information. a first lane information acquisition means for acquiring as lane information, the second lane information acquisition means for acquiring the lane information based on the vehicle position information and map information as the second lane information, the upper Symbol first When the lane information comparing means for comparing the lane information and the second lane information and the lane information comparing means determine that the first lane information is substantially equal to the second lane information, If it is determined that the first lane information is different from the second lane information while the first lane information is set to the first lane information, the first lane information is determined based on the previous lane information and the second lane information. Lane information setting to set lane information And a stage, the lane information setting means, in the lane information comparing means, said at least one of the parameters according to the first lane information, but almost equal to the parameter according to the second lane information corresponding to the respective parameters When it is determined that there is no vehicle, the above-mentioned vehicle relative to the lane estimated from the temporal change rate of the lateral position of the vehicle relative to the lane according to the first lane information and the value of the yaw rate actually generated on the vehicle. The lateral position of the vehicle relative to the lane is set by comparing the temporal change rate of the lateral position .

  According to the travel control device for a vehicle according to the present invention, it is possible to reliably perform control such as lane keep control and departure prevention control with high accuracy without restricting road parameters more than necessary.

BRIEF DESCRIPTION OF THE DRAWINGS It is structure explanatory drawing of the steering system of the vehicle which concerns on one Embodiment of this invention. 5 is a flowchart of a steering control program according to an embodiment of the present invention. It is an explanatory view of feedforward control of steering control concerning one embodiment of the present invention. It is an explanatory view of lateral position feedback control of steering control concerning one embodiment of the present invention. It is an explanatory view of yaw angle feedback control of steering control concerning one embodiment of the present invention. It is explanatory drawing of the lane information acquired from the own vehicle positional information and map information which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described based on the drawings.

  In FIG. 1, reference numeral 1 denotes an electric power steering apparatus in which the steering angle can be set independently of the driver input, and in the electric power steering apparatus 1, the steering shaft 2 is connected to the vehicle body frame (not shown) via the steering column 3. It is rotatably supported, with one end extending to the driver's seat side and the other end extending to the engine compartment side. A steering wheel 4 is fixed at an end of the steering shaft 2 on the driver's seat side, and a pinion shaft 5 is connected at an end extending to the engine compartment side.

  A steering gear box 6 extending in the vehicle width direction is disposed in the engine room, and a rack shaft 7 is inserted through and supported by the steering gear box 6 so as to be capable of reciprocating. A pinion (not shown) formed on the rack shaft 7 is engaged with a pinion formed on the pinion shaft 5 to form a rack-and-pinion steering gear mechanism.

  Further, left and right ends of the rack shaft 7 are respectively protruded from an end of the steering gear box 6, and a front knuckle 9 is continuously provided at the end via a tie rod 8. The front knuckle 9 rotatably supports the left and right wheels 10L and 10R as steered wheels, and is rotatably supported by the vehicle body frame. Therefore, when the steering wheel 4 is operated and the steering shaft 2 and the pinion shaft 5 are rotated, the rack shaft 7 is moved in the left and right direction by the rotation of the pinion shaft 5, and the front knuckle 9 is a king pin shaft (shown in FIG. And the left and right wheels 10L and 10R are steered in the left and right direction.

  Further, an electric power steering motor (electric motor) 12 is connected to the pinion shaft 5 via the assist transmission mechanism 11, and assist and setting of steering torque to be applied to the steering wheel 4 by the electric motor 12 are set. The steering torque is added such that the target steering angle is reached. The electric motor 12 is driven by the motor drive unit 21 when a control amount is output from the steering control unit 20 described later to the motor drive unit 21.

  The steering control unit 20 recognizes the forward environment of the vehicle and acquires forward environment information. The forward environment recognition device 31 detects the vehicle position information (latitude, longitude, movement direction, etc.) and detects the vehicle on the map information. Navigation system 32 for displaying the position and guiding the route to the destination, vehicle speed sensor 33 for detecting the vehicle speed V, steering angle sensor 34 for detecting the steering angle θH, and yaw rate for detecting the yaw rate (dθs / dt) of the vehicle A sensor 35 is connected.

  The front environment recognition device 31 is, for example, attached at a fixed distance in front of a ceiling in a vehicle room, and a pair of cameras that perform stereo imaging of an object outside the vehicle from different viewpoints, and stereo image processing that processes image data from this camera It consists of a device.

  The processing of the image data from the camera in the stereo image processing device of the front environment recognition device 31 is performed as follows, for example. First, for one stereo image pair in the traveling direction of the host vehicle taken by the camera, distance information is obtained from the amount of displacement of the corresponding position, and a distance image is generated.

  In recognition of data of lane markings such as white lines, based on the knowledge that the lane markings have high brightness compared to the road surface, the brightness change in the width direction of the road is evaluated to determine the left and right white lines in the image plane. Locate the image on the image plane. The real-space position (x, y, z) of this lane marking is based on the position (i, j) on the image plane and the parallax calculated for this position, that is, based on the distance information. It is calculated from a well-known coordinate conversion formula. In the present embodiment, the coordinate system of the real space set based on the position of the host vehicle is, for example, as shown in FIG. 4, with the road surface just below the center of the stereo camera as the origin and the x-axis in the vehicle width direction The vehicle height direction is y-axis, and the vehicle length direction (distance direction) is z-axis. At this time, the xz plane (y = 0) coincides with the road surface when the road is flat. The road model is expressed by dividing the traveling lane of the host vehicle on the road into a plurality of sections in the distance direction and connecting the left and right lane lines in each section in a predetermined approximation. In the present embodiment, although the example of recognizing the shape of the traveling path based on the image from one set of cameras has been described, the other is to obtain the image information from a single-eye camera or a color camera. It is good. Thus, the front environment recognition device 31 constitutes a first lane information acquisition means.

  Further, the navigation system 32 is a well-known system, for example, receives a radio signal from a GPS (Global Positioning System) satellite and acquires vehicle position information (latitude, longitude), and a vehicle speed sensor The vehicle speed V is acquired from 33, and movement direction information is acquired by a geomagnetic sensor or a gyro sensor or the like. Then, the navigation system 32 includes a navigation ECU that generates route information for realizing the navigation function, a map database that stores map information (supplier data and data updated by the steering control unit 20), for example, liquid crystal A display unit such as a display (all not shown) is configured.

  The navigation ECU superimposes route information to the destination designated by the user on the map image and displays it on the display unit, and the current position of the vehicle based on the detected information such as the position, speed, and traveling direction of the vehicle. Is superimposed on the map image on the display unit. Further, in the map database, information necessary for constructing a road map, such as node data and facility data, is stored. The node data relates to the position and shape of the road that constitutes the map image, and, for example, the coordinates (latitude, longitude) of a point (node point Pn) on the road including the branch point (intersection) of the road, the node point Pn The direction of the road that includes the type (for example, information such as expressway, arterial road, city road), the type of road at the node point Pn (straight section, arc section (arc curve section), clothoid curve section (relaxation section) ) And curve curvature κ (or radius) data are included. Therefore, as shown in FIG. 6, the travel path of the own vehicle is specified by the position on the map where the current position of the vehicle is overlapped, and the travel path of the own vehicle is set as the target travel path. According to the information of the node point Pn (k) closest to the road surface, traveling road information such as curve curvature κ (or radius) of the road and the direction of the road is acquired. Further, the facility data includes data on facility information existing near each node point Pn, and is stored in association with the node data (or link data in which the node is present). Thus, the navigation system 32 constitutes a second lane information acquisition means.

  Then, the steering control unit 20 acquires lane information based on the image information from the front environment recognition device 31 as first lane information according to the flowchart of FIG. Lane information based on vehicle position information and map information is acquired as second lane information, and first lane information and second lane information are compared based on the second lane information, and the first If it is determined that the lane information is substantially equal to the second lane information, the first lane information is set as the lane information, while if it is determined that the first lane information is different from the second lane information, the previous time The lane information is set based on the lane information and the second lane information, and steering control is performed based on the lane information. As described above, the steering control unit 20 is configured to have the functions of a first lane information acquisition unit, a second lane information acquisition unit, a lane information comparison unit, and a lane information setting unit.

  Hereinafter, the steering control program executed by the steering control unit 20 will be described with reference to the flowchart of FIG.

  First, in step (hereinafter abbreviated as "S") 101, from the front environment recognition device 31, as the first lane information based on image information, the curvature κc of the lane, the vehicle's anti-lane yaw angle θc, the lateral position in the lane Calculate xoc. Here, the subscript “c” of κc, θc, and xoc indicates that the data is based on image information.

The left and right lane boundary lines on the xz coordinate plane as shown in FIGS. 3 to 5 can be approximated by, for example, a quadratic expression of x = A · z ² + B · z + C by the method of least squares.

  Specifically, the lane line on the left side of the host vehicle is approximated by the following equation (1) by the method of least squares.

x = AL · z ² + BL · z + CL (1)
Further, the lane line on the right side of the host vehicle is approximated by the following equation (2) by the method of least squares.

x = AR · z ² + BR · z + CR (2)
Here, “AL” and “AR” in the above-mentioned equations (1) and (2) indicate the curvatures of the respective curves, and the curvature は l of the left lane line is 2 · AL, the right side The curvature rr of the lane markings is 2 · AR. Therefore, the curvature κc of the lane based on the image information is expressed by the following equation (3) (see FIG. 3).

c c = (2 · AL + 2 · AR) / 2 = AL + AR (3)
Further, “BL” and “BR” in the equations (1) and (2) indicate the inclinations of the respective curves in the width direction of the vehicle, and “CL” and “CR” indicate the respective curves of the respective curves. Indicates the position in the width direction of the vehicle.

  Therefore, the to-lane yaw angle θc of the host vehicle based on the image information is calculated by the following equation (4) (see FIG. 5).

θc = tan ⁻¹ ((BL + BR) / 2) (4)
Further, the in-lane lateral position xoc (from the center of the lane) based on the image information can be calculated by the following equation (5) (see FIG. 4).

xoc = (CL + CR) / 2 (5)
Next, in S102, the curvature 取得 m of the lane and the lane-to-lane yaw angle θm of the vehicle are acquired from the navigation system 32 as second lane information based on the vehicle position information and the map information. Here, the subscript “m” of κm and θm indicates that the data is based on the vehicle position information and the map information. The curvature κm of the lane based on the vehicle position information and the map information is information acquired from the information of the node point Pn (k) closest to the position Po (k) of the vehicle, as described above. In addition, the opposite lane yaw angle θm of the vehicle based on the vehicle position information and the map information is the traveling direction of the vehicle obtained at the previous vehicle position Po (k−1) and the current vehicle position Po (k). It is calculated by the difference between (angle) and the road azimuth at the node point Pn (k) closest to the current position Po (k) of the vehicle.

  Then, the process proceeds to S103, and the following four determinations (equations (6), (7), (8), (9)) are executed.

| Κm | + Eκm> | κc | (6)
| Dmm / dt | + DEκm> | dκc / dt | (7)
| Θm | + Eθm> | θc | (8)
| Dθ m / dt | + DE θ m> | d θ c / dt | (9)
Here, dκm / dt is the temporal change rate of the curvature κm of the lane based on the vehicle position information and the map information, dκc / dt is the temporal change rate of the curvature κc of the lane based on the image information, and dθm / dt is the self The temporal change rate of the vehicle's opposite lane yaw angle θm based on the vehicle position information and the map information, dθc / dt is the temporal change rate of the vehicle's opposite lane yaw angle θc based on the image information. Further, Eκm, DEκm, Eθm, DEθm are error ranges set in advance by the navigation system 32 and other experiments.

  If all the determinations in the equations (6), (7), (8), and (9) hold as a result of the determination in S103, the process proceeds to S104, and the curvature κ of the lane is determined based on the image information. Set the curvature c c (κ = κ c), set the opposite lane yaw angle θ c based on image information as the opposite lane yaw angle θ of the vehicle (θ = θ c), and set the lane based on image information as the lateral position xo of the vehicle Set the inside lateral position xoc (xo = xoc).

  On the other hand, if one or more determinations of any one of the equations (6), (7), (8), and (9) are not satisfied as a result of the determination in S103, the process proceeds to S105.

  In S105, first, the curvature κ of the lane and the anti-lane yaw angle θ of the vehicle are set by the following equations (10) and (11).

κ = κ (k−1) + (dκm / dt) · Δt (10)
θ = θ (k−1) + (dθ m / dt) · Δt (11)
Here, Δt is a step time. Also, the subscript “(k−1)” indicates that it is the previous value.

  That is, with regard to the curvature κ of the lane and the anti-lane yaw angle θ of the vehicle, it is considered that the value based on the image information contains many errors, so that the vehicle position information can be accurately detected based on the previously set value. The final value is set from the rate of change of the value based on the map information.

  Next, in S106, the temporal change rate Dx of the lateral position in the lane is calculated, for example, by the following equation (12).

Dx = V · Δt · sin (dθs / dt) (12)
Next, in S107, the absolute value | Dxoc | of the temporal change rate of the lateral position xoc in the lane based on the image information and the absolute value | Dx | of the temporal change rate of the lateral position in the lane calculated in S106 are obtained. Compare.

  As a result of the determination in S107, in the case of | Dx | S | Dxoc |, it is judged that there is little error in the in-lane lateral position xoc based on the image information by the image information, and the process proceeds to S108. The in-lane lateral position xoc is set as xo based on the image information (xo = xoc).

Conversely, in the case of | Dx | <| Dxoc |, it is judged that the in-lane lateral position xoc based on the image information based on the image information contains a large amount of error, and the process proceeds to S109. Set in-lane lateral position x o
xo = xo (k−1) + V · Δt · sin (θm) (13)
After the setting of each lane information is completed in S104, S108, and S109, the process proceeds to S110, and predetermined steering control (lane keeping control, lane departure prevention control, etc.) is executed, and the program is exited.

  As an example of steering control executed in S110, the case of performing lane keeping control in which the center of the lane is the target course will be described.

  First, a feedforward control current value Iff for traveling along a target course is calculated, for example, by the following equation (14).

Iff = Giff κ ... (14)
Here, Giff indicates a feedforward gain set in advance by experiment, calculation or the like.

  Further, the lateral position feedback control current value Ifb for traveling along the target course is calculated, for example, by the following equation (15).

Ifb = Gifb · Δx (15)
Here, Gifb is a gain set in advance by experiment, calculation or the like. Further, as shown in FIG. 4, Δx is calculated by the following equation (16).

Δx = (xl + xr) / 2−xv (16)
In this equation (16), xv is the x coordinate of the estimated vehicle trajectory at the z coordinate of the forward fixation point (0, zv) of the vehicle, and is the forward gaze distance (z coordinate) of the forward fixation point (0, zv) In the present embodiment, zv is calculated by zv = tc · V. Here, tc is a preview time set in advance, and is set to, for example, 1.2 sec.

Therefore, xv can be calculated, for example, by the following equation (17) when using the specifications of the vehicle, the stability factor As specific to the vehicle, and the like based on the traveling state of the vehicle.
xv = (1/2) · (1 / (1 + As · V 2)) · (θH / Lw)
· (Tc · V) ² ... (17)
Here, Lw is a wheel base. In equation (16), xl is the x coordinate of the left white line at the z coordinate of the forward gaze point (0, zv), and xr is the x coordinate of the right white line at the z coordinate of the forward gaze point (0, zv) is there.

The above xv can also be calculated by the following equation (18) or equation (19) using the vehicle speed V and the yaw rate (dθ / dt).
xv = (1/2) ((dθ / dt) / V) (V · tc) ² ... (18)
xv = (1/2) · κ · (V · tc) ² (19)
Further, a yaw angle feedback control current value By by which feedback control of the yaw angle of the vehicle is performed to the yaw angle along the target route is calculated, for example, by the following equation (20).

Ifby = Gifby · θ (20)
Here, Gifby is a gain set in advance by experiment, calculation or the like.

  Then, for example, the control current value Ia is calculated by the following equation (21), and is output to the motor drive unit 21.

Ia = Iff + Ifb + Ifby (21)
In the present embodiment, the lane keeping control is described as an example of the steering control, but it goes without saying that the lane departure prevention control can also be controlled using each lane information set as described above. Yes. Furthermore, based on each lane information set as described above, the present invention can be applied to various controls (such as driving support control and automatic driving control) that require parameters relating to the lanes.

  As described above, according to the embodiment of the present invention, lane information based on image information from the forward environment recognition device 31 is acquired as first lane information, and vehicle position information and map information from the navigation system 32 are obtained. Lane information based on the second lane information, and comparing the first lane information with the second lane information based on the second lane information, the first lane information being the second lane information If it is determined that the first lane information is set to be the lane information, if it is determined that the first lane information is different from the second lane information, the previous lane information and the second lane information are determined. Lane information is set based on the above, and steering control is performed based on the lane information. Therefore, control such as lane keeping control and departure prevention control is performed accurately while ensuring the response of turning at high vehicle speeds and the performance of in-lane correction steering without limiting road parameters more than necessary. It becomes possible.

Reference Signs List 1 electric power steering device 2 steering shaft 4 steering wheel 5 pinion shaft 10L, 10R wheel 12 electric motor 20 steering control unit (first lane information acquisition unit, second lane information acquisition unit, lane information comparison unit, lane information setting means)
21 Motor drive unit 31 Forward environment recognition device (first lane information acquisition means)
32 Navigation system (second lane information acquisition means)
33 Vehicle speed sensor 34 Steering angle sensor 35 Yaw rate sensor

Claims (5)

In a travel control device of a vehicle that acquires lane information of a traveling lane and performs steering control based on the lane information,
First lane information acquisition means for acquiring the lane information based on image information as first lane information;
A second lane information acquisition unit that acquires the lane information based on the vehicle position information and the map information as second lane information;
And lane information comparing means for comparing the first lane information on SL and the second lane information,
If the lane information comparison means determines that the first lane information is substantially equal to the second lane information, the first lane information is set to the lane information, while the first lane information is set. Lane information setting means for setting the lane information based on the previous lane information and the second lane information when it is determined that the second lane information is different from the second lane information;
Equipped with
When the lane information setting means determines that at least one of the parameters according to the first lane information is not substantially equal to the parameter according to the second lane information corresponding to the parameters. Furthermore, the temporal change rate of the lateral position of the vehicle with respect to the lane according to the first lane information and the temporal position of the lateral position of the vehicle with respect to the lane estimated from the value of the yaw rate actually generated in the vehicle. Set the lateral position of the vehicle relative to the lane by comparing with the rate of change
Travel control device for a vehicle, characterized and this. Comparing the above first lane information and the second lane information on Symbol lane information comparing means, and the curvature of the lane, and the temporal change rate of the curvature of the lane, a pair lanes yaw angle of the vehicle, the Ri Ah each parameter of the temporal change rate of the pair lane yaw angle of the vehicle,
The lane information setting means, the first of said vehicle with respect to lane by lane information is inferred from the value of the yaw rate actually generated on the temporal change rate and the vehicle lateral position of the vehicle with respect to the lane results of the comparison between the time rate of change of lateral position, inferred from the value of the yaw rate temporal change rate of the lateral position of the vehicle with respect to the lane according to the first lane information is actually generated in the free-vehicle If it exceeds the temporal change rate of the lateral position of the vehicle with respect to the lane that is, the lateral position of the vehicle with respect to the traffic lane, lateral position and the second lane of the vehicle with respect to the lane previously set set based on the pair lane yaw angle of the vehicle acquired by the information acquiring unit, and the temporal change rate of the lateral position of the vehicle with respect to the lane according to the first lane information is actually generated in the vehicle Yole If for lane inferred from bets value smaller than the time rate of change of lateral position of the host vehicle, the lateral position of the vehicle with respect to the lane according to the first lane information as a lateral position of the vehicle with respect to the lane The travel control device for a vehicle according to claim 1, wherein Comparing the above first lane information and the second lane information on Symbol lane information comparing means, and the curvature of the lane, and the temporal change rate of the curvature of the lane, a pair lanes yaw angle of the vehicle, the Ri Ah each parameter of the temporal change rate of the pair lane yaw angle of the vehicle,
The lane information setting means is the lane information comparison means, and when it is determined that the parameters according to the first lane information and the parameters according to the second lane information are all substantially equal. travel control device for a vehicle according to claim 1 or 2, wherein the lateral position of the vehicle according to the lane information for a pair lane yaw angle and the lane curvature and the vehicle in the lane and sets as the lane information . Comparing the above first lane information and the second lane information on Symbol lane information comparing means, and the curvature of the lane, and the temporal change rate of the curvature of the lane, a pair lanes yaw angle of the vehicle, the Ri Ah each parameter of the temporal change rate of the pair lane yaw angle of the vehicle,
Said lane information setting means, by the lane information comparing means determines that said at least one of said parameters according to the first lane information, but the parameters and not properly such substantially according to the second lane information corresponding to the respective parameters If you, claim 1, characterized in that to set the curvature of the lane, in accordance with the temporal change rate of the curvature of the obtained lane curvature and the second lane information acquisition means of the lane previously set to traveling control apparatus for a vehicle according to claim 3. Comparing the above first lane information and the second lane information on Symbol lane information comparing means, and the curvature of the lane, and the temporal change rate of the curvature of the lane, a pair lanes yaw angle of the vehicle, the Ri Ah each parameter of the temporal change rate of the pair lane yaw angle of the vehicle,
Said lane information setting means, by the lane information comparing means, said at least one of said parameters according to the first lane information, but the parameters and not properly such substantially that due to the second lane information corresponding to the respective parameters If it is determined that the vehicle's opposite lane yaw angle is determined according to the temporal change rate of the previously set vehicle opposite lane yaw angle and the second lane information acquisition means acquired by the second lane information acquisition means The travel control device for a vehicle according to any one of claims 1 to 4 , wherein the setting is performed.
Ru.

Images