JP6784629B2 - Vehicle steering support device - Google Patents

Description

According to the present invention, the vehicle can travel along the traveling lane without moving downward in the inclined direction even when the vehicle is traveling on a traveling road inclined in the vehicle width direction by autonomous navigation. Regarding the steering support device of the vehicle.

Conventionally, in this type of steering support device, the position of the own vehicle is based on the position information received from the positioning satellite (GNSS (Global Navigation Satellite System) satellite including GPS satellite) by the car navigation system mounted on the own vehicle. (Own vehicle position) and traveling azimuth angle are obtained, and by map matching with the road map data stored in advance, the position information in the center of the driving lane closest to the own vehicle position and the road azimuth angle are acquired, and the own vehicle There is known a technique for automatically steering a vehicle so as to travel along the center of the lane.

In addition, when the own vehicle is equipped with a front recognition means such as a camera, the front recognition means recognizes the lane marking line (white line) that divides the left and right of the lane (traveling lane) in which the own vehicle is traveling. Then, by detecting the position of the own vehicle in the driving lane and the yaw angle (anti-lane yaw angle) of the own vehicle in the traveling lane with respect to the driving lane, the vehicle is automatically steered so as to travel along the center of the driving lane. The technology to do this is also known.

However, in the car navigation system, if the reception accuracy from the positioning satellite is reduced due to the influence of buildings around the driving lane, weather conditions, etc., the position error of the own vehicle and the accuracy error of the traveling azimuth data will be obtained. It becomes large and it becomes difficult to continue automatic steering. Similarly, even if the lane marking line (white line) deteriorates or the recognition accuracy of the lane marking line by the front recognition means deteriorates due to the influence of the reflection of sunlight from the road surface, etc., the automatic steering should be continued. May be difficult.

As a countermeasure against this, in Patent Document 1 (Japanese Unexamined Patent Publication No. 2017-13586), the driver performs steering override during driving control such as lane keeping (lane keeping) and automatic steering in automatic driving. In this case, it is presumed that the vehicle is operating the steering wheel to return to the center of the lane because it is biased toward the lane marking line, and the horizontal position when the steering override is completed is set as the vehicle shape point (horizontal position starting point). We proposed a technology that sets and continues steering control from that position.

Japanese Unexamined Patent Publication No. 2017-13586

The technology disclosed in the above-mentioned literature is such that the steering control is continued by returning the own vehicle to the center of the lane by operating the steering wheel of the driver, so that the reception accuracy from the positioning satellite and the left and right of the lane by the forward recognition means are used. Even if at least one of the recognition accuracy of the left and right section lines that divide the vehicle deteriorates, it is possible to continue steering control as long as it is a curved road (curve) with a constant radius of curvature as well as a straight road. Is.

However, when the traveling lane has a road lateral gradient angle (cant angle), an error occurs in steering control due to the influence of this lateral gradient angle, and the own vehicle gradually moves in the inclined direction. There is an inconvenience. As a result, the driver has to return the vehicle to the center of the lane by steering override each time, which is inconvenient because complicated operations are required.

In view of the above circumstances, the present invention automatically follows the traveling lane even when the vehicle is traveling in a traveling lane having a lateral gradient angle in a state where the acquisition level of the own vehicle position information is lowered. It is an object of the present invention to provide a steering support device for a vehicle that can continue steering and reduce the burden on the driver.

The vehicle steering support device according to the present invention includes a vehicle speed detecting means for detecting the vehicle speed of the own vehicle, an inclination angle detecting means for detecting the inclination angle in the vehicle width direction of the own vehicle, road orientation angle data, and a road lateral inclination angle. The road map storage means for storing the road map data including the data, the own vehicle position information acquisition means for acquiring the own vehicle position information based on the information from the external information source, and the own vehicle position information acquisition means acquired. The road azimuth angle data and the road lateral gradient angle data are read from the road map data stored in the road map storage means based on the own vehicle position information, and the own vehicle moves in the direction indicated by the road azimuth angle data. The steering control means is provided with a steering control means for performing steering control so as to travel, and the steering control means acquires whether or not the acquisition level of the own vehicle position information acquired by the own vehicle position information acquisition means is lowered. When it is determined by the level determination means and the acquisition level determination means that the acquisition level has decreased, the estimated own vehicle position is set by autonomous navigation, and the estimated own vehicle position is stored in the road map storage means. Detected by the own vehicle position estimation means to be matched with the road map data, the road lateral gradient angle data in the road map data at the estimated own vehicle position set by the own vehicle position estimation means, and the inclination angle detection means. Calculated by the anti-lane yaw angle calculating means for calculating the anti-lane yaw angle of the own vehicle with respect to the direction indicated by the road azimuth angle data and the anti-lane yaw angle calculating means based on the inclination angle in the vehicle width direction. It has a target steering torque calculation means for obtaining a target steering torque based on the anti-lane yaw angle and the road azimuth angle.

According to the present invention, when it is determined that the acquisition level of the own vehicle position information is lowered, the estimated own vehicle position is set by autonomous navigation, and the estimated own vehicle position is matched with the road map data to estimate the own vehicle. Based on the road lateral slope angle data in the road map data at the vehicle position and the slope angle in the vehicle width direction, the anti-lane yaw angle of the own vehicle with respect to the direction indicated by the road azimuth data is calculated, and this anti-lane yaw angle is calculated. Since the target steering torque is calculated based on the above and the road azimuth, when the vehicle is traveling in a driving lane having a lateral gradient angle while the acquisition level of the own vehicle position information is lowered. Even so, it is possible to continue automatic steering along the traveling lane. As a result, the burden on the driver can be reduced.

Schematic configuration of a vehicle equipped with a steering support device Flowchart showing automatic steering control routine Flowchart showing the anti-lane yaw angle calculation processing subroutine Explanatory drawing of own vehicle running on a running path with a cant angle by automatic steering Front view of own vehicle traveling on a cant-angled driving path by automatic steering Top view of own vehicle running on a running path with a cant angle by automatic steering

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the vehicle (own vehicle) 1 has left and right front wheels FL and FR and left and right rear wheels RL and RR, and the left and right front wheels FL and FR are steering wheels, and a steering mechanism 2 such as a rack and pinion mechanism 2 It is connected to the tie rod 3 via a tie rod 3. Further, the steering mechanism 2 is continuously provided with a steering shaft 5 for fixing the handle 4 to the tip. When the driver operates the steering wheel 4, the front wheels FL and FR are steered via the steering mechanism 2.

Further, an EPS motor 7 of the electric power steering (EPS) device 6 is continuously provided on the steering shaft 5 via a transmission mechanism (not shown). The EPS device 6 has an EPS motor 7 and an EPS control unit (EPS_ECU) 8, and the EPS_ECU 8 controls the assist torque applied to the steering shaft 5 by the EPS motor 7.

The EPS_ECU 8 includes, for example, a driving support control unit (DSS (Driving Support System) _ECU) 11 and a navigation control device (Navi_ECU) 17 described later via an in-vehicle network using CAN (Controller Area Network) communication or the like. It is connected freely in both directions.

When the DSS_ECU 11 is in the active state, the EPS_ECU 8 sets the EPS torque corresponding to the target steering torque set by the DSS_ECU 11, drives the EPS motor 7, and causes the own vehicle 1 to take a target traveling path (for example, described later). , The center of the lane) is traced and steering control is performed. Further, when the DSS_ECU 11 is inactive, that is, when the reception accuracy from the positioning satellite described later is lowered to a state where it is difficult to continue the automatic steering control of the own vehicle 1, the automatic steering control is performed. Since the vehicle is stopped, an assist torque is set to assist the steering torque applied to the steering wheel 4 by the driver.

The DSS_ECU 11 has a steering angle sensor 12 attached to the steering shaft 5 to detect the steering angle of the steering wheel 4 and a yaw rate sensor to detect the yaw rate acting on the own vehicle 1 as various parameters required for performing automatic steering control. 13. Detects behavior acting on the own vehicle 1, such as a vehicle speed sensor 14 as a vehicle speed detecting means for detecting the vehicle speed (own vehicle speed) of the own vehicle 1, and a 3-axis acceleration sensor (gyro sensor) 15 as an inclination angle detecting means. Signals from the sensors are input.

Here, the 3-axis acceleration sensor 15 detects accelerations acting in three axial directions orthogonal to each other in the front-rear direction, the lateral (vehicle width) direction, and the vertical direction of the own vehicle 1, and the own vehicle 1 detects the acceleration. When traveling on a straight road at a constant speed, acceleration in the front-rear direction and the lateral direction is detected as an inclination angle in the front-rear direction and the vehicle width direction of the own vehicle 1.

Further, the navigation_ECU 17 has a positioning radio wave receiving unit, and is used as an external information source such as GPS (Global Positioning System), GLONASS (Global Navigation Satellite System), QZSS (Quasi-Zenith Satellite System) received by the receiving antenna 17a. The position of the own vehicle is sequentially acquired based on the position information which is the external information from the GNSS positioning satellite of. Therefore, this navigation_ECU 17 has a function as the own vehicle position information acquisition means of the present invention.

Further, a road map database 18 as a road map storage means having high-precision road map (dynamic map) data is connected to the navigation_ECU 17. The road map database 18 is provided in a large-capacity storage medium such as a hard disk, and the stored high-precision road map data can be used as static map data such as the shape of roads and structures and lane information for each road. It is composed of dynamically changing information such as traffic regulations, accidents, traffic jams, vehicles, pedestrians, and signals in the above, and the dynamic information is updated according to changes in the surrounding environment.

Further, as the static map data, there is road map data stored in the nodes i (see FIGS. 4 and 6) set at predetermined intervals along the center of the lane width. This road map data includes road position information (latitude, longitude, altitude), road shape information (curve / straight type, radius of curvature of curve, road lateral slope angle (cant angle), which is the slope angle in the road width direction. Data, road orientation data, etc.) are included.

Although not shown, the above-mentioned in-vehicle network includes, in addition to EPS_ECU8, DSS_ECU11, and Navi_ECU17, an engine control unit, a transmission control unit, a vehicle control (VDC) device including brake control, and the like. Units that control the running state of the vehicle 1 in automatic driving or the like are connected to each other so as to be able to communicate with each other, and each of these control units is mainly composed of a microcomputer.

On the other hand, reference numeral 21 is a front recognition device as a front recognition means which is an external information source, and acquires (acquires) the traveling lane of the own vehicle 1 by acquiring the traveling environment information which is the external information in front of the own vehicle 1. .. The front recognition device 21 is mainly composed of a microcomputer, and also has an in-vehicle camera 22 composed of a stereo camera including a main camera 22a and a sub camera 22b.

The front recognition device 21 performs image processing on the front driving environment information image captured by the in-vehicle camera 22, and recognizes the lane markings that divide the left and right of the traveling lane in, for example, lane keeping control in automatic driving, and owns the vehicle. Generates image information necessary for driving 1 along the center of the lane. The front recognition device 21 may employ a millimeter-wave radar, an infrared laser radar, or the like instead of the stereo camera, as long as it can acquire information on the driving environment in front of the lane markings, or a monocular with these. It may be adopted in combination with a camera.

By the way, the DSS_ECU 11 sequentially detects the position of the own vehicle 1 based on the position information from the positioning satellite, and controls the steering so that the own vehicle 1 travels along the taxiway to the destination set on the road map. Do. At the same time, the left and right lane markings Ll and Lr (see FIGS. 4 and 6) that divide the traveling lane are recognized based on the traveling environment information from the front recognition device 21, and lane keeping control is performed so as to travel in the center thereof. Therefore, the DSS_ECU 11 has a function as the automatic steering control means of the present invention.

In this case, even if both the recognition accuracy of the left and right lane markings by the forward recognition device 21 and the reception accuracy of the positioning satellite are lowered, not only a straight road but also a curved road (curve) having a constant radius of curvature is used. If so, it is possible to continue the automatic steering control because the steering angle is constant as long as it continues. However, when the traveling lane has a lateral road gradient (cant), an error occurs in steering control due to the influence of the lateral force generated in the inclined direction, and the own vehicle 1 moves little by little in the inclined direction. It ends up.

Therefore, the DSS_ECU 11 estimates the position of the own vehicle 1 and the traveling azimuth when one or both of the image recognition accuracy by the front recognition device 21 and the reception accuracy of the positioning satellite deteriorate, and the cant road. The steering angle to be transmitted to the EPS_ECU 8 is calculated so that the own vehicle 1 travels along the target traveling path (center of the lane) even during traveling.

Specifically, the automatic steering control by the DSS_ECU 11 is executed according to the automatic steering control routine shown in FIG. This routine is executed at predetermined calculation cycles after each system mounted on the own vehicle 1 is activated. First, in step S1, the traveling environment information from the front recognition device 21 is read and used as the own vehicle position information. The left and right lane markings Ll and Lr that divide the left and right of the traveling lane are acquired, and the process proceeds to step S2.

In step S2, the recognition (acquisition) level of the left and right lane markings Ll and Lr is checked. If the left and right division lines Ll and Lr are recognized, it is determined that the recognition level is good, and the process proceeds to step S3. If at least one of the left and right lane markings Ll and Lr cannot be recognized due to deterioration or reflection of sunlight from the road surface, it is determined that the recognition (acquisition) level is lowered, and step S5. Jump to.

Proceeding to step S3, the position information from the positioning satellite received by the navigation_ECU 17 is read. The processing in steps S1 and S3 corresponds to the own vehicle position information acquisition means of the present invention.

In step S4, the reception accuracy is checked from the positioning satellite based on this position information to check whether the acquisition level is good or not. Whether or not the acquisition level is good is determined based on, for example, the number of captured positioning satellites, the average reception intensity, and position error information.

Then, the number of captured satellites is a predetermined value (for example, 4) or more, the average reception intensity is equal to or more than a preset threshold value, and the position information measured this time is a tolerance set in advance with respect to the position information previously positioned. If it is within the range, it is determined that the radio wave reception state from the positioning satellite is good, and the process proceeds to step S5. On the other hand, when the number of captured satellites is less than a predetermined value, the average reception intensity is less than a preset threshold value, or the position information measured this time deviates from the preset allowable range with respect to the position information previously positioned. If it is determined that the presence is present, it is determined that the acquisition status of the radio wave reception from the positioning satellite is deteriorated, and the process branches to step S6. The processing in steps S2 and S4 described above corresponds to the acquisition level determination means of the present invention.

When it is determined that the reception condition is good and the process proceeds to step S5, the high-precision road map data provided in the road map database 18 is referred to based on the position information of the own vehicle 1, and the direction of travel closest to the own vehicle position is obtained. The road azimuth data stored in the node is (see FIGS. 4 and 6) is read. Note that in FIGS. 4 and 6, the road azimuths stored in each node i are indicated by arrows for convenience. Further, in this road azimuth data, for example, true north N is set as a reference azimuth angle of 0 °.

Next, the process proceeds to step S7, and the left and right lane markings Ll and Lr recognized based on the traveling environment information from the front recognition device 21 and the own vehicle position and node is calculated based on the position information from the positioning satellite are stored. Based on the road azimuth angle data, the yaw rate correction value for driving the own vehicle 1 along the center of the lane is obtained, and the process proceeds to step S11.

On the other hand, when the vehicle branches from step S2 or step S4 to step S6, the position of the own vehicle is estimated. This estimated vehicle position is set using well-known autonomous navigation. That is, the estimated own vehicle position is set based on the lateral angular acceleration detected by the 3-axis acceleration sensor 15 and the own vehicle speed detected by the vehicle speed sensor 14, and this is map-matched with the high-precision road map data. The processing in this step corresponds to the own vehicle position estimation means of the present invention.

Next, the process proceeds to step S8, and the yaw angle (anti-lane yaw angle) calculation process of the own vehicle 1 with respect to the road azimuth angle direction of the traveling lane is executed. This anti-lane yaw angle is performed according to the anti-lane yaw angle calculation processing subroutine shown in FIG. The processing in this subroutine corresponds to the anti-lane yaw angle calculating means of the present invention.

As described above, if the traveling lane of the own vehicle 1 is horizontal without tilting in the lateral direction, steering is performed even if at least one of the recognition accuracy of the left and right section lines by the front recognition device 21 and the reception accuracy of the positioning satellite is lowered. By keeping the angle constant, it is possible to continue the automatic steering control. However, as shown in FIG. 5, when the traveling lane is inclined at the road lateral inclination angle (cant angle) σ, the own vehicle 1 is affected by the lateral force generated in the downward inclination even if the steering angle is constant. It becomes easier to receive and move downward incline. Therefore, in this subroutine, the yaw angle (anti-lane yaw angle) ψ generated in the own vehicle 1 due to the influence of the cant angle σ is calculated.

First, in step S21, the inclination angle (roll angle) θ in the vehicle width direction of the own vehicle 1 detected by the 3-axis acceleration sensor 15 is read. Next, the process proceeds to step S22, and the cant angle σ stored in the node is is read.

After that, in step S23, the yaw angle (anti-lane yaw angle) ψ with respect to the lane traveling direction (direction indicated by the road azimuth) of the own vehicle 1 is calculated. When the own vehicle 1 is traveling along the traveling lane, the roll angle θ and the cant angle σ shown in FIG. 5 show the same values. However, as shown in FIG. 6, when the own vehicle 1 is turning downward in an inclination, there is a difference between the roll angle θ and the cant angle σ. Because this difference is caused by the anti-lane yaw angle ψ
tanθ ＝ tanσ ・ cosψ
The relational expression of is established.

Therefore, the estimated value of the anti-lane yaw angle ψ is obtained from this relational expression, and the process proceeds to step S9 of the steering control routine shown in FIG. Since there is no difference between the roll angle θ and the cant angle σ on a flat road with a cant angle of 0 °, the yaw angle ψ with respect to the lane is approximately 0 °.

By the way, when the 3-axis acceleration sensor 15 tries to detect the roll angle θ, a centrifugal force is applied to the gravitational acceleration as a disturbance factor while traveling on a curve, so that an error is likely to occur in the detected value of the roll angle θ. In this case, the disturbance factor due to centrifugal force is calculated based on the radius of curvature and cant angle σ of the curve stored in the node i and the own vehicle speed detected by the vehicle speed sensor 14, and this is calculated from the detected value of the 3-axis acceleration sensor 15. By removing it, an accurate roll angle θ can be obtained.

The radius of curvature of the curve and the cant angle do not change significantly on the continuous running path, and even if the node i read this time deviates slightly from the position of the own vehicle, the shape of the traveling lane of the own vehicle 1 , The radius of curvature of the read curve and the cant angle σ do not deviate significantly.

Further, when proceeding to step S9, the road azimuth angle data stored in the node i (see FIG. 6) in front of the own vehicle 1 is read based on the estimated own vehicle position information set in step S6 described above. Next, the process proceeds to step S10, the lane yaw angle ψ is time-differentiated, and the azimuth angle of the own vehicle 1 in the traveling direction (own vehicle azimuth) is stored in the node i read in step S9. The yaw rate correction value for returning to the angular direction is calculated, and the process proceeds to step S11.

When the vehicle proceeds from step S7 or step S10 to step S11, the target steering torque for driving the own vehicle 1 by tracing the target traveling path is calculated. Specifically, based on the road azimuth data stored in the node is closest to the own vehicle 1 and the node i in front of the node is, the target travel path (own vehicle azimuth) on which the own vehicle 1 should travel is determined. Set and set the target steering angle for traveling along this target travel path.

Then, this target steering angle is corrected by the yaw rate correction value calculated in step S7 or step S10 described above to calculate a new target steering angle, and then the steering angle detected by the steering angle sensor 12 is set as a new target. Calculate the target steering torque to converge to the steering angle and exit the routine. The process in step S11 corresponds to the target steering torque calculation means of the present invention.

This target steering torque is read by EPS_ECU 8. The EPS_ECU 8 sets the EPS torque corresponding to the target steering torque, drives the EPS motor 7, and controls the steering of the own vehicle 1.

As described above, in the present embodiment, the anti-lane yaw angle ψ based on the road direction angle closest to the own vehicle 1 stored in the high-precision road map data is obtained, and the anti-lane yaw angle ψ is set based on the anti-lane yaw angle ψ. Since the yaw rate correction value is used to correct the target steering angle for driving the own vehicle 1 along the target traveling path, it is difficult for the front recognition device 21 to recognize the lane marking that divides the left and right sides of the traveling lane. Or, even when driving in a driving lane with a cant angle with the reception accuracy from the positioning satellite by the navigation_ECU 17 lowered, it is possible to continue automatic steering along the driving lane. The burden on the person can be further reduced.

The present invention is not limited to the above-described embodiment, and for example, the above-mentioned steering control can be applied not only to automatic driving but also to lane keeping control.

1 ... own vehicle,
2 ... Steering mechanism,
4 ... Handle,
6 ... EPS device,
7 ... EPS motor,
8 ... EPS control unit,
11 ... Driving support control unit,
12 ... Steering angle sensor,
13 ... Yaw rate sensor,
14 ... Vehicle speed sensor,
15 ... Axis accelerometer,
17 ... Navi_ECU,
17a ... Receiving antenna,
18 ... Road map database,
21 ... Forward recognition device,
22 ... In-vehicle camera,
FL, FR ... Front wheels,
RL, RR ... rear wheel,
i, is ... node,
Ll, Lr ... Left and right lane markings,
θ: Tilt angle (roll angle) in the vehicle width direction,
σ… Road cross slope angle (cant angle),
ψ… Yaw angle to lane

Claims (4)

Vehicle speed detecting means for detecting the vehicle speed of the own vehicle and
An inclination angle detecting means for detecting the inclination angle of the own vehicle in the vehicle width direction,
A road map storage means that stores road map data including road azimuth data and road lateral slope data, and
Own vehicle position information acquisition means to acquire own vehicle position information based on information from external information sources,
The road azimuth angle data and the road lateral gradient angle data are read from the road map data stored in the road map storage means based on the own vehicle position information acquired by the own vehicle position information acquisition means, and the own vehicle. Is provided with a steering control means for steering control so as to travel in the direction indicated by the road azimuth data.
The steering control means
An acquisition level determining means for determining whether or not the acquisition level of the own vehicle position information acquired by the own vehicle position information acquisition means is lowered, and
When it is determined by the acquisition level determining means that the acquisition level has decreased, the estimated own vehicle position is set by autonomous navigation, and the estimated own vehicle position is stored in the road map data stored in the road map storage means. Vehicle position estimation means to match and
The road is based on the road lateral gradient angle data in the road map data at the estimated own vehicle position set by the own vehicle position estimating means and the inclined angle in the vehicle width direction detected by the inclined angle detecting means. An anti-lane yaw angle calculating means for calculating the anti-lane yaw angle of the own vehicle with respect to the direction indicated by the azimuth angle data, and
A vehicle steering support device comprising: a target steering torque calculation means for obtaining a target steering torque based on the anti-lane yaw angle calculated by the anti-lane yaw angle calculating means and the road azimuth. The external information source is a positioning satellite.
The own vehicle position information acquisition means acquires the own vehicle position information based on the position information from the positioning satellite, and obtains the own vehicle position information.
The vehicle steering support device according to claim 1, wherein the acquisition level determining means examines the reception accuracy from the positioning satellite to determine whether or not the acquisition level is lowered. The external source is a forward recognition means
The own vehicle position information acquisition means acquires the own vehicle position information based on the lane marking information that divides the left and right sides of the traveling lane acquired by the front recognition means.
The vehicle steering support device according to claim 1 or 2, wherein the acquisition level determining means determines whether or not the acquisition level of the lane marking is lowered by the front recognition means. The anti-lane yaw angle calculating means sets the anti-lane yaw angle ψ when the inclination angle in the vehicle width direction is θ and the road lateral gradient angle is σ.
tanθ ＝ tanσ ・ cosψ
The vehicle steering support device according to any one of claims 1 to 3, wherein the vehicle steering support device is obtained from the relational expression of the above.

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