JP6723301B2 - Vehicle steering system - Google Patents

Description

The present invention relates to a vehicle steering system that automatically drives a vehicle along a target travel locus.

In recent years, a vehicle steering system that calculates a target traveling locus of a vehicle using highly accurate vehicle position information and highly accurate map information obtained from a satellite and performs steering control so that the vehicle automatically travels along the target traveling locus is provided. Development is underway as one of the autonomous driving technologies. Generally, in such a vehicle steering system, when the feedback control gain for calculating the target steering angle is increased, the tracking accuracy of the target traveling locus is improved, but the steering wheel operation becomes sensitive to the situation change. The number of times the steering direction is changed increases and the behavior of the vehicle becomes unstable. Therefore, Patent Document 1 discloses a technique for reducing the number of changes in the steering direction and stabilizing the behavior of the vehicle by reducing the feedback control gain when traveling on a straight road as compared to when traveling on a non-straight road. There is.

JP, 2017-144769, A

As described above, in the conventional vehicle steering system, the feedback control gain is reduced on a straight road to stabilize the behavior of the vehicle. However, in this method, when a situation in which high traveling path tracking accuracy is required while traveling on a straight road, for example, when another vehicle is running side by side in an adjacent traveling lane, the feedback control gain is small, There was a possibility that the tracking accuracy of the traveling locus was insufficient, and that the vehicle might come too close to other vehicles running in parallel.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a vehicle steering system that can appropriately set a feedback control gain according to the situation in which the host vehicle is placed. ..

A vehicle steering apparatus according to the present invention is a vehicle steering apparatus that performs steering control so that a vehicle automatically travels along a target traveling locus of a vehicle, and a target traveling locus calculation unit that calculates the target traveling locus, and at least the above A calculation unit that calculates a target steering angle based on a curvature of a target travel locus and a lateral deviation of the vehicle from the target travel locus is provided. The target steering angle is calculated by increasing the feedback control gain used for the calculation of the target steering angle as compared with the case where the predetermined situation is not met, and the predetermined situation is the situation where the lane change of the vehicle is instructed. The calculation unit calculates the target steering angle by increasing the feedback control gain as compared with a situation in which lane change is not instructed, and the target traveling locus calculation unit calculates road map data and satellite positioning information. The target traveling locus is calculated based on the position and direction of the vehicle obtained by using the vehicle.

According to the vehicle steering system of the present invention, the feedback control gain can be increased to secure the traveling locus following precision in a predetermined situation where high traveling locus following precision is required. On the other hand, when the situation is not the predetermined situation, it is possible to travel with stable vehicle behavior.

FIG. 1 is a block diagram showing an overall configuration of an automatic driving vehicle to which a vehicle steering system according to the present invention can be applied. 1 is a block diagram showing a configuration of a vehicle steering system according to Embodiment 1 of the present invention. It is a figure which shows the relationship between road map data and a target travel path typically. 3 is a flowchart showing an operation of the vehicle steering system according to the first embodiment of the present invention. It is a figure which shows the change of a driving lane typically. It is a block diagram which shows the structure of the vehicle steering apparatus of Embodiment 2 which concerns on this invention. 7 is a flowchart showing an operation of the vehicle steering system according to the second embodiment of the present invention. FIG. 11 is a block diagram showing a configuration of a vehicle steering system according to a first modification of the second embodiment of the present invention. 9 is a flowchart showing an operation of the vehicle steering system of the first modification of the second embodiment according to the present invention. FIG. 13 is a block diagram showing a configuration of a vehicle steering system of a modified example 2 of the second embodiment according to the present invention. 9 is a flowchart showing the operation of the vehicle steering system of the second modification of the second embodiment according to the present invention. FIG. 13 is a block diagram showing a configuration of a vehicle steering system of a modified example 3 of the second embodiment according to the present invention. 9 is a flowchart showing the operation of the vehicle steering system of the third modification of the second embodiment according to the present invention. FIG. 1 is a block diagram showing an overall configuration of an automatic driving vehicle to which a vehicle steering system according to the present invention can be applied. It is a block diagram which shows the structure of the vehicle steering apparatus of Embodiment 3 which concerns on this invention. 9 is a flowchart showing an operation of the vehicle steering system according to the third embodiment of the present invention. FIG. 1 is a block diagram showing an overall configuration of an automatic driving vehicle to which a vehicle steering system according to the present invention can be applied. It is a block diagram which shows the structure of the vehicle steering apparatus of Embodiment 4 which concerns on this invention. It is a figure which shows the relationship between road map data and a target travel path typically. It is a figure which shows the hardware constitutions which implement|achieve the vehicle steering device of Embodiments 1-4 which concern on this invention. It is a figure which shows the hardware constitutions which implement|achieve the vehicle steering device of Embodiments 1-4 which concern on this invention.

<Embodiment 1>
Hereinafter, Embodiment 1 according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an overall configuration of an autonomous driving vehicle 1 capable of automatic traveling, as an example of a vehicle to which a vehicle steering system 100 according to a first embodiment of the present invention can be applied.

As shown in FIG. 1, a self-driving vehicle 1 has a steering device 4 that constitutes an EPS (Electric Power Steering) system attached to a steering wheel 3 that operates two tires 2 of front wheels. The steering device 4 automatically steers the steering wheel 3 on the basis of the control signal. The steering device 4 has an EPS motor and its controller.

The vehicle steering system 100 is also referred to as an ADAS-ECU (Advanced Driving Assistance Systems-Electronic Control Unit), and has high-accuracy map information such as road map data stored in the map information storage device 20 and a vehicle position/azimuth detection device. The target traveling locus is calculated based on the highly accurate vehicle position and the vehicle direction detected in 10, and the steering wheel 3 is automatically steered along the target traveling locus.

The vehicle position and direction detection device 10 uses the satellite positioning information from the artificial satellite 8 such as the GNSS (Global Navigation Satellite System), GPS (Global Positioning System) satellite, and quasi-zenith satellite received by the antenna 7 The position (latitude, longitude) and the own vehicle direction (calculated from the time change of the position) are detected, and the detected own vehicle position and the own vehicle direction are given to the vehicle steering system 100.

The road map data stored in the map information storage device 20 includes the position of the traveling lane (latitude, longitude), road type, speed limit, traveling lane width, tunnel, bridge, position of the toll collection point (latitude, longitude), etc. A dynamic map, which includes various data of 1) and is practically applicable, is applicable.

Further, the self-driving vehicle 1 is provided with a lane change instruction switch 30 used when an occupant desires to change lanes, and information for turning the lane change instruction switch 30 on and off is given to the vehicle steering system 100.

FIG. 2 is a functional block diagram showing the configuration of the vehicle steering system 100. As shown in FIG. 2, the vehicle steering system 100 includes a target traveling locus calculation unit 40 and a target steering angle calculation unit 50.

The target traveling locus calculation unit 40 receives information from the vehicle position/azimuth detecting device 10, the map information storage device 20, and the lane change instruction switch 30 to calculate the target traveling locus of the own vehicle, and the reference coordinate system of the own vehicle. The curvature (R) of the target traveling locus above and the lateral position deviation (Ye) of the target traveling locus of the own vehicle are output.

More specifically, the target travel locus calculation unit 40 sets the current vehicle position (latitude, longitude) as the center of the XY axes, sets the X direction as the vehicle direction, and obtains road map data close to the vehicle position. The target traveling locus is read out from the map information storage device 20, and the target traveling locus is calculated as an approximate curve based on the read road map data.

FIG. 3 is a diagram schematically showing the relationship between the road map data and the target travel locus. As shown in FIG. 3, the road map data is represented by a plurality of node data, and the target traveling locus calculation unit 40 includes, before and after the node data close to the current position of the autonomous driving vehicle 1, among the read node data. By connecting, an approximate curve indicated by a broken line up to a predetermined forward distance of the own vehicle, for example, 20 m ahead is calculated and set as a target travel locus. A least square method or the like can be used as a method of connecting the preceding and following node data.

The target steering angle calculation unit 50 performs target steering of the own vehicle based on the curvature (R) of the target travel locus output from the target travel locus calculation unit 40 and the lateral deviation (Ye) of the own vehicle position from the target travel locus. The angle is calculated and output. At this time, the feedback control gain used to calculate the target steering angle is changed depending on whether the information of the lane change instruction switch 30 is ON or OFF. This will be further described later.

The target steering angle output from the target steering angle calculation unit 50 is given to the steering device 4 to automatically steer the steering wheel 3.

By calculating the target traveling locus using the information from the vehicle position and direction detecting device 10 and the map information storage device 20, it is possible to obtain a highly accurate target traveling locus.

Next, the operation of the vehicle steering system 100 according to the first embodiment will be described with reference to the flowchart shown in FIG. The operation of the flowchart of FIG. 4 is repeatedly executed while the vehicle is traveling.

First, the target traveling locus calculation unit 40 acquires the vehicle position and the vehicle direction from the vehicle position and direction detection device 10 (step S1).

Next, the target traveling locus calculation unit 40 acquires road map information around the vehicle from the map information storage device 20 based on the acquired vehicle position and vehicle direction (step S2).

Next, the target traveling locus calculation unit 40 and the target steering angle calculation unit 50 acquire information about whether the lane change instruction switch 30 is on or off (step S3).

Next, the target traveling locus calculation unit 40 calculates a target traveling locus up to a predetermined forward distance of the vehicle, for example, 20 m ahead (step S4). Here, when the lane change instruction switch 30 is in the OFF state and there is no lane change instruction, the target travel locus is calculated so that the vehicle travels while maintaining the current lane as described with reference to FIG. On the other hand, when the lane change instruction switch 30 is on and there is a lane change instruction, the target traveling locus calculation unit 40 calculates a new target traveling locus so as to change from the previous traveling lane to another lane. .. FIG. 5: is a figure which shows typically the case where the lane is changed from the present driving lane to the lane on the right.

This new target travel locus is, for example, of a plurality of node data of the road map data, the node data close to the current position of the autonomous driving vehicle 1 is used as a base point, and the shortest route to reach the changed lane is taken, It is calculated by connecting the front and back of node data. In this case, the vehicle speed and the yaw rate (the changing speed of the rotation angle in the turning direction) are taken into consideration in the calculation so that the course is not changed suddenly. The vehicle speed and the yaw rate are detected by a vehicle speed sensor and a yaw rate sensor (not shown) mounted on the autonomous vehicle 1.

Further, in step S4, the curvature (R) of the target traveling locus on the reference coordinate system of the own vehicle and the lateral position deviation (Ye) between the own vehicle and the target traveling locus are calculated and output.

Next, the target steering angle calculation unit 50 performs target steering based on the curvature (R) of the target travel locus output from the target travel locus calculation unit 40 and the lateral position deviation (Ye) between the own vehicle and the target travel locus. Before calculating the corner, the target steering angle calculation unit 50 determines whether or not there is a lane change instruction (step S5).

Then, when the lane change instruction switch 30 is in the ON state and there is a lane change instruction, that is, when a predetermined situation is reached, the target steering angle is calculated in step S6. On the other hand, when the lane change instruction switch 30 is off and there is no lane change instruction, that is, when the predetermined situation is not reached, the target steering angle is calculated in step S7. The following general formula (1) is used to calculate the target steering angle.

Target steering angle=Kff×curvature of target travel locus+Kfb×horizontal position deviation between own vehicle and target travel locus... (1)
Here, Kff is a feedforward control gain by which the curvature of the target travel locus is multiplied, and is one value fixed for each vehicle type. Kfb is a feedback control gain that is multiplied by the lateral position deviation between the own vehicle and the target travel locus.

Generally, a control system that determines a manipulated variable by multiplying a deviation between a current value and a target value by a gain is called feedback control, and a control system that determines a manipulated variable by multiplying a target value by a gain is called a feedforward control.

Here, the embodiment according to the present invention is characterized in that the feedback control gain has two values, a large value and a small value. In the first embodiment, when there is a lane change instruction, in step S6. The target steering angle is calculated using a large value, and if there is no lane change instruction, the target steering angle is calculated using a small value in step S7.

The large value of the feedback control gain is set to a value which is 1.5 to 2 times the small value of the feedback control gain.

Finally, based on the target steering angle calculated by the target steering angle calculation unit 50, automatic steering is performed in the steering device 4 (step S8), and a series of operations ends.

As described above, in the vehicle steering system 100 according to the first embodiment, the feedback control gain in the calculation of the target steering angle is made larger than that in the normal state only when the lane change instruction is issued. As a result, the accuracy of following the target travel locus at the time of changing lanes can be made higher than that at the normal time, so that safe lane changing becomes possible. Further, when the lane is changed, the feedback control gain is reduced to allow the vehicle to travel with stable vehicle behavior.

<Second Embodiment>
In the first embodiment described above, an example is shown in which the feedback control gain of the target travel locus is made larger than that in the normal time when the lane is changed, and the accuracy of following the target travel locus is made higher than that in the normal time. Even if the vehicle runs on a narrow road, if the accuracy of following the target travel locus is insufficient, a situation may occur in which the distance from the outside of the lane suddenly becomes shorter. The vehicle steering system 101 according to the second embodiment of the present invention can suppress the occurrence of such a situation.

FIG. 6 is a functional block diagram showing the configuration of the vehicle steering system 101. As shown in FIG. 6, the vehicle steering system 101 includes a traveling lane width detection unit 71, a target traveling locus calculation unit 40, and a target steering angle calculation unit 51. In FIG. 6, the same components as those of the vehicle steering system 100 described with reference to FIG. 2 are designated by the same reference numerals, and duplicate description will be omitted.

Further, the vehicle steering system 101 can be applied to the automatic driving vehicle 1 shown in FIG. 1, and in the second embodiment, description will be made assuming that the vehicle steering system 101 is mounted on the automatic driving vehicle 1 instead of the vehicle steering system 100. To do. The lane change instruction switch 30 in the autonomous driving vehicle 1 shown in FIG. 1 can be used together with the vehicle steering system 101 according to the second embodiment. In that case, the lane change instruction switch 30 turns on or off. The information may be input to the target traveling locus calculation unit 40 and the target steering angle calculation unit 51.

The traveling lane width detection unit 71 determines the vehicle position based on the vehicle position and the vehicle direction acquired from the vehicle position and direction detection device 10, and the road map information around the vehicle acquired from the map information storage device 20. The traveling lane width of the road is detected, and the detected traveling lane width is output to the target steering angle calculation unit 51.

Next, the operation of the vehicle steering system 101 according to the second embodiment will be described with reference to the flowchart shown in FIG. In FIG. 7, steps other than steps S31 and S51 are the same as those in the first embodiment shown in FIG. 4, and redundant description will be omitted. The operation of the flowchart of FIG. 7 is repeatedly executed while the vehicle is traveling.

In step S1, the target traveling locus calculation unit 40 acquires the vehicle position and the vehicle direction from the vehicle position and direction detection device 10, and the traveling lane width detection unit 71 also acquires the vehicle position and the vehicle direction, In step S2, the target traveling locus calculation unit 40 acquires road map information around the vehicle from the map information storage device 20, and the traveling lane width detection unit 71 also acquires road map information around the vehicle. The road map information stores, as a set, the traveling lane position defined by the latitude and longitude of the center point of the lane and the data indicating the width of the traveling lane. The traveling lane width detection unit 71 searches the road map information for a traveling lane position that is the closest to the vehicle position defined by the latitude and longitude, that is, the latitude and longitude are stored, and is stored as a set with the retrieved traveling lane position. The running lane width data is acquired (step S31) and input to the target steering angle calculation unit 51.

In step S4, the target traveling locus calculation unit 40 calculates the target traveling locus, and calculates the curvature (R) of the target traveling locus on the vehicle reference coordinate system and the lateral position deviation (Ye) between the own vehicle and the target traveling locus. Based on the curvature (R) of the target travel locus output from the target travel locus calculation unit 40 and the lateral position deviation (Ye) between the own vehicle and the target travel locus, the target steering angle calculation unit 51 outputs The target steering angle is calculated, but before that, the target steering angle calculation unit 51 determines whether or not the traveling lane width is narrower than a threshold value (step S51).

Then, when the traveling lane width is narrower than the threshold value, that is, when the predetermined situation is reached, the target steering angle is calculated in step S6. On the other hand, when the traveling lane width is equal to or larger than the threshold value, that is, when the predetermined condition is not satisfied, the target steering angle is calculated in step S7.

Here, the embodiment according to the present invention is characterized in that the feedback control gain has two values, a large value and a small value. In the second embodiment, when the traveling lane width is narrower than the threshold value, Calculates the target steering angle using a large value in step S6, and if the traveling lane width is equal to or greater than the threshold value, calculates the target steering angle using a small value in step S7.

As described above, in the second embodiment, when the traveling lane width is narrow, the feedback control gain in the target steering angle calculation is made larger than that in the normal time. As a result, when the traveling lane width is narrow, the accuracy of following the target traveling locus can be made higher than in the normal time, and traveling that does not exceed the traveling lane width can be realized. Further, when the traveling lane width is wide, the feedback control gain can be reduced to perform traveling with stable vehicle behavior.

<Modification 1>
The vehicle steering system 101 according to the second embodiment includes the traveling lane width detection unit 71, the traveling lane width detection unit 71 detects the traveling lane width of the road at the vehicle position, and detects the detected traveling lane width. Although the configuration for outputting to the target steering angle calculation unit 51 is shown, in the vehicle steering system 102 shown in FIG. 8 as a first modification of the second embodiment, a tunnel detection unit 72 is used instead of the traveling lane width detection unit 71. Have

FIG. 8 is a functional block diagram showing the configuration of the vehicle steering system 102. As shown in FIG. 8, the vehicle steering system 102 includes a tunnel detection unit 72, a target travel locus calculation unit 40, and a target steering angle calculation unit 52. Note that, in FIG. 8, the same components as those of the vehicle steering system 100 described with reference to FIG. 2 are denoted by the same reference numerals, and overlapping description will be omitted.

Further, the vehicle steering system 102 is applicable to the automatic driving vehicle 1 shown in FIG. 1, and in the first modification, it will be described as being mounted on the automatic driving vehicle 1 instead of the vehicle steering system 100. .. The lane change instruction switch 30 in the autonomous driving vehicle 1 shown in FIG. 1 can be used together with the vehicle steering system 102 of the first modification, and in that case, the lane change instruction switch 30 is turned on or off. The information may be input to the target traveling locus calculation unit 40 and the target steering angle calculation unit 52.

The tunnel detection unit 72 determines that the vehicle position is near the tunnel based on the vehicle position and the vehicle direction acquired from the vehicle position and direction detection device 10, and the road map information around the vehicle acquired from the map information storage device 20. Or not, and outputs it to the target steering angle calculation unit 52 as tunnel detection information.

Next, the operation of the vehicle steering system 102 according to the first modification of the second embodiment will be described using the flowchart shown in FIG. In FIG. 9, steps other than steps S32 and S52 are the same as those in the first embodiment shown in FIG. 4, and redundant description will be omitted. The operation of the flowchart of FIG. 9 is repeatedly executed while the vehicle is traveling.

In step S1, the target traveling locus calculation unit 40 acquires the vehicle position and the vehicle direction from the vehicle position and direction detection device 10, and the tunnel detection unit 72 also acquires the vehicle position and the vehicle direction. In the above, the target traveling locus calculation unit 40 acquires the road map information around the own vehicle from the map information storage device 20, and the tunnel detection unit 72 also acquires the road map information around the own vehicle. The road map information stores a set of data indicating the traveling lane position defined by the latitude and longitude of the center point of the lane and the tunnel position. The tunnel detection unit 72 searches the road lane information for a traveling lane position that is closest to the own vehicle position defined by latitude and longitude, that is, the latitude and longitude are close, and is stored as a set with the retrieved traveling lane position. Based on the tunnel position data, tunnel detection information indicating whether or not a tunnel exists around the vehicle is acquired (step S32) and input to the target steering angle calculation unit 52.

In step S4, the target traveling locus calculation unit 40 calculates the target traveling locus, and calculates the curvature (R) of the target traveling locus on the vehicle reference coordinate system and the lateral position deviation (Ye) between the own vehicle and the target traveling locus. The target steering angle calculation unit 52 outputs, based on the curvature (R) of the target travel locus output from the target travel locus calculation unit 40 and the lateral position deviation (Ye) between the own vehicle and the target travel locus, Before calculating the target steering angle, the target steering angle calculation unit 52 determines whether or not the vehicle is near the tunnel (step S52). It should be noted that the case where the own vehicle is near the tunnel refers to, for example, the case where the own vehicle is located inside the tunnel and 100 m before and after the tunnel.

Then, when the vehicle is near the tunnel, that is, when a predetermined situation occurs, the target steering angle is calculated in step S6. On the other hand, when the vehicle is not near the tunnel, that is, when the vehicle is not in the predetermined situation, the target steering angle is calculated in step S7.

Here, the embodiment according to the present invention is characterized in that the feedback control gain has two values, a large value and a small value. In the first modification, when the vehicle is near the tunnel, step S6 is performed. In step S7, the target steering angle is calculated using a large value, and when the vehicle is not near the tunnel, the target steering angle is calculated using a small value in step S7.

As described above, in the first modified example, when the host vehicle is near the tunnel, the feedback control gain in the calculation of the target steering angle is made larger than that in the normal time. As a result, when the own vehicle is in the vicinity of the tunnel, the follow-up accuracy of the target traveling locus can be made higher than that in the normal time, and traveling near the tunnel can follow the target traveling locus. Further, when the own vehicle is not near the tunnel, the feedback control gain can be reduced to allow the vehicle to travel stably.

<Modification 2>
The vehicle steering system 101 according to the second embodiment includes the traveling lane width detection unit 71, the traveling lane width detection unit 71 detects the traveling lane width of the road at the vehicle position, and detects the detected traveling lane width. Although the configuration for outputting to the target steering angle calculation unit 51 is shown, in the vehicle steering system 103 shown in FIG. 10 as a second modification of the second embodiment, a bridge detection unit 73 is used instead of the traveling lane width detection unit 71. Have

FIG. 10 is a functional block diagram showing the configuration of the vehicle steering system 103. As shown in FIG. 10, the vehicle steering system 103 includes a bridge detection unit 73, a target traveling locus calculation unit 40, and a target steering angle calculation unit 53. 10, the same components as those of the vehicle steering system 100 described with reference to FIG. 2 are designated by the same reference numerals, and duplicate description will be omitted.

Further, the vehicle steering system 103 can be applied to the automatic driving vehicle 1 shown in FIG. 1, and in the second modification, it will be described as being mounted on the automatic driving vehicle 1 instead of the vehicle steering system 100. .. It should be noted that the lane change instruction switch 30 in the autonomous driving vehicle 1 shown in FIG. 1 can be used together with the vehicle steering system 103 of the second modification, and in that case, the lane change instruction switch 30 is turned on or off. The information may be input to the target traveling locus calculation unit 40 and the target steering angle calculation unit 53.

The bridge detection unit 73 determines that the vehicle position is near the bridge based on the vehicle position and the vehicle direction acquired from the vehicle position and direction detection device 10, and the road map information around the vehicle acquired from the map information storage device 20. Is detected and output to the target steering angle calculation unit 52 as bridge detection information.

Next, the operation of the vehicle steering system 103 according to the second modification of the second embodiment will be described using the flowchart shown in FIG. In FIG. 11, steps other than steps S32 and S52 are the same as those in the first embodiment shown in FIG. 4, and redundant description will be omitted. The operation of the flowchart of FIG. 11 is repeatedly executed while the vehicle is traveling.

In step S1, the target traveling locus calculation unit 40 acquires the own vehicle position and the own vehicle direction from the own vehicle position and direction detection device 10, and the bridge detection unit 73 also acquires the own vehicle position and the own vehicle direction. In the above, the target traveling locus calculation unit 40 acquires the road map information around the own vehicle from the map information storage device 20, and the bridge detection unit 73 also acquires the road map information around the own vehicle. In the road map information, the traveling lane position defined by the latitude and longitude of the center point of the lane and the data indicating the bridge position are stored as a set. The bridge detection unit 73 searches the road map information for a traveling lane position that is closest to the own vehicle position defined by latitude and longitude, that is, the latitude and longitude are close, and is stored as a set with the retrieved traveling lane position. Based on the bridge position data, bridge detection information indicating whether or not a bridge exists around the own vehicle is acquired (step S33) and input to the target steering angle calculation unit 53.

In step S4, the target traveling locus calculation unit 40 calculates the target traveling locus, and calculates the curvature (R) of the target traveling locus on the vehicle reference coordinate system and the lateral position deviation (Ye) between the own vehicle and the target traveling locus. Based on the curvature (R) of the target travel locus output from the target travel locus calculation unit 40 and the lateral position deviation (Ye) between the own vehicle and the target travel locus, the target steering angle calculation unit 53 outputs Before calculating the target steering angle, the target steering angle calculation unit 53 determines whether or not the host vehicle is near the bridge (step S53). The case where the vehicle is near the bridge refers to, for example, the case where the vehicle is located on the bridge or 100 m before and after the bridge.

Then, when the host vehicle is near the bridge, that is, when a predetermined situation occurs, the target steering angle is calculated in step S6. On the other hand, if the host vehicle is not near the bridge, that is, if it is not in the predetermined situation, the target steering angle is calculated in step S7.

Here, the embodiment according to the present invention is characterized in that the feedback control gain has two values, a large value and a small value. In the second modification, when the own vehicle is near the bridge, step S6 is performed. In step S7, the target steering angle is calculated using a large value, and when the vehicle is not near the bridge, the target steering angle is calculated using a small value in step S7.

As described above, in the second modification, when the host vehicle is near the bridge, the feedback control gain in the target steering angle calculation is made larger than that in the normal time. As a result, when the host vehicle is near the bridge, the accuracy of following the target travel locus can be made higher than in normal times, and traveling near the bridge can follow the target travel locus. Further, when the host vehicle is not near the bridge, the feedback control gain can be reduced to allow stable vehicle behavior.

<Modification 3>
The vehicle steering system 101 according to the second embodiment includes the traveling lane width detection unit 71, the traveling lane width detection unit 71 detects the traveling lane width of the road at the vehicle position, and detects the detected traveling lane width. Although the configuration for outputting to the target steering angle calculation unit 51 is shown, in the vehicle steering system 104 shown in FIG. 12 as a modified example 3 of the second embodiment, instead of the traveling lane width detection unit 71, toll collection points are detected. It has a section 74.

FIG. 12 is a functional block diagram showing the configuration of the vehicle steering system 104. As shown in FIG. 12, the vehicle steering system 104 includes a toll collection point detection unit 74, a target travel locus calculation unit 40, and a target steering angle calculation unit 54. Note that, in FIG. 12, the same components as those of the vehicle steering system 100 described with reference to FIG. 2 are denoted by the same reference numerals, and overlapping description will be omitted.

Further, the vehicle steering system 104 is applicable to the self-driving vehicle 1 shown in FIG. 1, and in the third modification, it will be described as being mounted on the self-driving vehicle 1 instead of the vehicle steering system 100. .. The lane change instruction switch 30 in the autonomous vehicle 1 shown in FIG. 1 can be used together with the vehicle steering system 104 of the third modification, and in that case, the lane change instruction switch 30 is turned on or off. The information may be input to the target traveling locus calculation unit 40 and the target steering angle calculation unit 54.

The toll collection point detection unit 74 determines the vehicle position based on the vehicle position and the vehicle direction acquired from the vehicle position and direction detection device 10, and the road map information around the vehicle acquired from the map information storage device 20. Is detected near the toll collection point and is output to the target steering angle calculation unit 54 as toll collection point detection information.

Next, the operation of the vehicle steering system 104 according to the modified example 3 of the second embodiment will be described using the flowchart shown in FIG. In FIG. 13, steps other than steps S34 and S54 are the same as those in the first embodiment shown in FIG. 4, and redundant description will be omitted. The operation of the flowchart in FIG. 13 is repeatedly executed while the vehicle is traveling.

In step S1, the target traveling locus calculation unit 40 acquires the own vehicle position and the own vehicle direction from the own vehicle position and direction detection device 10, and the toll collection point detection unit 74 also acquires the own vehicle position and the own vehicle direction. In step S2, the target traveling locus calculation unit 40 acquires the road map information around the own vehicle from the map information storage device 20, and the toll collection point detection unit 74 also acquires the road map information around the own vehicle. The road map information stores a set of data indicating the traveling lane position defined by the latitude and longitude of the center point of the lane and the toll collection point position. The toll collection point detection unit 74 searches the road map information for the traveling lane position that is the closest to the vehicle position defined by the latitude and longitude, that is, the latitude and longitude are stored, and stores it as a set with the retrieved traveling lane position. Based on the data of the toll collection point position that is being provided, the toll collection point detection information indicating whether there is a toll collection point around the own vehicle is acquired (step S34), and the target steering angle calculation unit 54 is obtained. input.

In step S4, the target traveling locus calculation unit 40 calculates the target traveling locus, and calculates the curvature (R) of the target traveling locus on the vehicle reference coordinate system and the lateral position deviation (Ye) between the own vehicle and the target traveling locus. Based on the curvature (R) of the target travel locus output from the target travel locus calculation unit 40 and the lateral position deviation (Ye) between the own vehicle and the target travel locus, the target steering angle calculation unit 54 outputs Before calculating the target steering angle, the target steering angle calculation unit 54 determines whether or not the vehicle is near the toll collection point (step S54). The case where the own vehicle is near the toll collection point is, for example, the case where the own vehicle is located within the toll collection point and 100 m before and after the toll collection point.

Then, when the own vehicle is near the toll collection point, that is, when a predetermined situation occurs, the target steering angle is calculated in step S6. On the other hand, when the own vehicle is not near the toll collection point, that is, when it is not in the predetermined situation, the target steering angle is calculated in step S7.

Here, the embodiment according to the present invention is characterized in that the feedback control gain has two values, a large value and a small value. In the third modification, when the own vehicle is near the toll collection point, Calculates the target steering angle using a large value in step S6, and calculates the target steering angle using a small value in step S7 if the vehicle is not near the toll collection point.

As described above, in the third modification, when the vehicle is near the toll collection point, the feedback control gain in the calculation of the target steering angle is made larger than that in the normal case. As a result, when the own vehicle is near the toll collection point, the follow-up accuracy to the target travel locus can be made higher than in the normal time, and the traveling near the toll collection locus can be realized. .. Further, when the own vehicle is not near the toll collection point, the feedback control gain can be reduced to allow the vehicle to run with stable behavior.

<Third Embodiment>
In the first embodiment, when the lane is changed, and in the second embodiment, when the traveling lane width is narrow, the feedback control gain of the target traveling locus is set to be larger than that in the normal time, and the accuracy of following the target traveling locus is higher than that in the normal time. However, if other vehicles or obstacles exist around the vehicle and the accuracy of following the target travel path is insufficient, a situation may occur in which the distance to other vehicles or obstacles suddenly becomes shorter. there is a possibility. The vehicle steering system 105 according to the third embodiment of the present invention can suppress the occurrence of such a situation.

The third embodiment according to the present invention will be described below with reference to the drawings. FIG. 14 is a block diagram showing an overall configuration of an autonomous driving vehicle 1A that is capable of automatically traveling, as an example of a vehicle to which the vehicle steering system 105 according to the third embodiment of the present invention can be applied. Note that, in FIG. 14, the same components as those of the autonomous driving vehicle 1 described with reference to FIG. 1 are denoted by the same reference numerals, and overlapping description will be omitted.

As shown in FIG. 14, the self-driving vehicle 1A includes a vehicle that travels in the immediate vicinity of the host vehicle, a surrounding detection sensor 60 that detects a sign, equipment, and the like located immediately outside the traveling lane. The peripheral detection sensor 60 is, for example, a millimeter wave radar, a laser radar, an ultrasonic sensor, or the like, and these are configured alone or in combination. The surroundings detection sensor 60 detects the presence or absence of other vehicles running in parallel with the own vehicle and the presence or absence of obstacles such as guardrails and walls existing along the traveling lane, and inputs them into the vehicle steering device 105 as surroundings detection information. In FIG. 14, the peripheral detection sensor 60 is arranged so as to detect the left and right of the autonomous driving vehicle 1A, but this is an example, and the arrangement position and the number are not limited to this.

FIG. 15 is a functional block diagram showing the configuration of the vehicle steering system 105. As shown in FIG. 15, the vehicle steering system 105 includes a target traveling locus calculation unit 40 and a target steering angle calculation unit 55, and the surrounding detection information detected by the surrounding detection sensor 60 is the target steering angle calculation unit. 55 is input. In FIG. 15, the same components as those of the vehicle steering system 100 described with reference to FIG. 2 are designated by the same reference numerals, and duplicate description will be omitted. Further, although the lane change instruction switch 30 is also provided in the autonomous driving vehicle 1A, this can be used together with the vehicle steering system 105 of the third embodiment. In that case, the lane change instruction switch 30 is used. The on/off information may be input to the target traveling locus calculation unit 40 and the target steering angle calculation unit 55.

Next, the operation of the vehicle steering system 105 according to the third embodiment will be described with reference to the flowchart shown in FIG. In FIG. 16, steps other than steps S35 and S55 are the same as those in the first embodiment shown in FIG. 4, and redundant description will be omitted. The operation of the flowchart in FIG. 16 is repeatedly executed while the vehicle is traveling.

In step S4, the target traveling locus calculation unit 40 calculates the target traveling locus, and calculates the curvature (R) of the target traveling locus on the vehicle reference coordinate system and the lateral position deviation (Ye) between the own vehicle and the target traveling locus. Based on the curvature (R) of the target travel locus output from the target travel locus calculation unit 40 and the lateral position deviation (Ye) between the own vehicle and the target travel locus, the target steering angle calculation unit 55 outputs Before calculating the target steering angle, the target steering angle calculation unit 55 acquires the peripheral detection information from the peripheral detection sensor 60 (step S35).

Then, when the vehicle and the obstacle are present around the own vehicle, that is, when the predetermined situation is reached, the target steering angle is calculated in step S6. On the other hand, if there is no vehicle or obstacle around the vehicle, that is, if the vehicle is not in a predetermined situation, the target steering angle is calculated in step S7.

Here, the embodiment according to the present invention is characterized in that the feedback control gain has two values, a large value and a small value. In the third embodiment, a vehicle and an obstacle exist around the host vehicle. In this case, the target steering angle is calculated using a large value in step S6, and when there is no vehicle or obstacle around the vehicle, the target steering angle is calculated using a small value in step S7.

As described above, in the third embodiment, when the vehicle and the obstacle are present around the host vehicle, the feedback control gain in the target steering angle calculation is made larger than that in the normal time. As a result, when the vehicle and obstacles are present around the host vehicle, the accuracy of following the target travel locus can be made higher than in normal times, and travel that follows the target travel locus can be realized. Further, when the vehicle and the obstacle are not present around the own vehicle, the feedback control gain can be reduced to allow the vehicle to travel with stable behavior.

<Embodiment 4>
In the first to third embodiments of the present invention described above, the vehicle position and direction detection device 10 detects the position and the vehicle direction of the vehicle using the positioning information from the artificial satellite, and stores the map information. A configuration is shown in which the position of the traveling lane, the road type, the regulation speed, the traveling lane width, the position of the tunnel, the bridge, the toll collection point, and the like are acquired together with the road map data stored in the device 20. The relative position between the vehicle and the road, the relative azimuth, and the shape of the road may be detected by using the image data taken by the front camera that shoots.

Hereinafter, a fourth embodiment according to the present invention will be described with reference to the drawings. FIG. 17 is a block diagram showing an overall configuration of an automatically driving vehicle 1B capable of automatic traveling as an example of a vehicle to which the vehicle steering system 106 according to the fourth embodiment of the present invention can be applied. In addition, in FIG. 17, the same components as those of the autonomous driving vehicle 1 described with reference to FIG. 1 are denoted by the same reference numerals, and overlapping description will be omitted.

As shown in FIG. 17, the self-driving vehicle 1B includes a front camera 70 that photographs the front of the vehicle. The front camera 70 may be a monocular camera or a stereo camera. Further, the camera is not limited to a visible light camera, and an infrared camera may be used, the type of camera may be changed according to the environment, or a combination may be used.

The front camera 70 detects the relative position between the host vehicle and the road, the relative azimuth, and the shape of the road using the acquired image data, and inputs them to the vehicle steering system 106. For example, binarized image processing and edge detection processing are performed on image data obtained by capturing the front with the front camera 70, and the left and right white lines of the vehicle are detected by Hough conversion or the like to determine the traveling lane width. It is possible to obtain the relative position of the left and right white lines with respect to the host vehicle, detect the current lateral position of the host vehicle, that is, the distance between the center point of the host vehicle and the left and right white lines, and also determine the curvature of the driving lane. The shape of the road can be acquired by detecting whether the road is straight or curved. Further, by performing pattern matching on the front image data, it is possible to detect tunnels, bridges, and toll collection points.

The self-driving vehicle 1B also includes the vehicle position/azimuth detection device 10 and the map information storage device 20, but these can be used together with the vehicle steering device 106 and may be used as an auxiliary. ..

FIG. 18 is a functional block diagram showing the configuration of the vehicle steering system 106. As shown in FIG. 16, the vehicle steering system 106 includes a target traveling locus calculation unit 41 and a target steering angle calculation unit 50, and the relative position between the vehicle and the road detected by the front camera 70, the relative azimuth, and the road. The information of the shape is input to the target travel locus calculation unit 41. In addition, in FIG. 18, the same components as those of the vehicle steering system 100 described with reference to FIG. 2 are denoted by the same reference numerals, and overlapping description will be omitted.

The difference from the vehicle steering system 100 is that the target traveling locus calculation unit 41 is input with information on the relative position between the vehicle and the road detected by the front camera 70, the relative direction, and the shape of the road. The computing unit 41 computes the target traveling locus based on these pieces of information, and calculates the curvature (R) of the target traveling locus on the own vehicle reference coordinate system and the lateral position deviation (Ye) between the own vehicle and the target traveling locus. Calculate

Further, in the vehicle steering system 106, similarly to the vehicle steering system 100, the feedback control gain used for calculating the target steering angle is changed depending on whether the information of the lane change instruction switch 30 is ON or OFF. Instead of the information of the lane change instruction switch 30, the feedback control gain of the target travel locus may be set to be larger than usual when the traveling lane width is narrow, and in the vicinity of the tunnel, the bridge, or the toll collection point. The feedback control gain of the target travel locus may be set to be larger than that in the normal time.

As described above, the relative position between the host vehicle and the road, the relative direction, and the shape of the road are detected using the image data captured by the front camera, and the target traveling locus is calculated using these pieces of information. , It is possible to obtain the target travel locus based on the new information.

<Other example of calculation method of target steering angle>
In the first to fourth embodiments described above, the target steering angle is calculated by using the mathematical expression (1), but the calculation method of the target steering angle is not limited to this. In addition to the lateral deviation from the target traveling locus, the calculation may be performed using the angular deviation between the own vehicle and the target traveling locus.

FIG. 19 is a diagram schematically showing the relationship between the road map data and the target travel locus, and the target travel locus calculation unit calculates the curvature (R) of the target travel locus and the lateral position of the vehicle position from the target travel locus. In addition to the deviation (Ye), the angular deviation (θe) between the own vehicle and the target travel locus is also output. Then, the target steering angle is calculated using the following mathematical expression (2).

Target steering angle=Kff×curvature of target traveling locus+Kfb1×lateral position deviation between own vehicle and target traveling locus+Kfb2×angle deviation between own vehicle and target traveling locus... (2)
Here, Kfb1 is a feedback control gain that multiplies the lateral position deviation between the own vehicle and the target traveling locus, and Kfb2 is a feedback control gain that multiplies the angular deviation between the own vehicle and the target traveling locus.

By switching the feed-bag control gain Kfb1 and the feed-bag control gain Kfb2 to be larger or smaller, similarly to the feed-bag control gain Kfb in the first to fourth embodiments, the follow-up accuracy to the target travel locus is further improved. be able to. The magnitude relationship between the feedback control gains Kfb1 and Kfb2 is not particularly limited, and the combination of the two is also not particularly limited.

Each unit of the vehicle steering systems 100 to 106 according to the first to fourth embodiments described above can be configured using a computer, and is realized by the computer executing a program. That is, the vehicle steering devices 100 to 106 are realized by the processing circuit 110 shown in FIG. 20, for example. A processor such as a CPU or a DSP (Digital Signal Processor) is applied to the processing circuit 110, and the functions of each unit are realized by executing a program stored in a storage device.

Note that dedicated hardware may be applied to the processing circuit 110. When the processing circuit 110 is dedicated hardware, the processing circuit 110 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. To do.

Further, FIG. 21 shows a hardware configuration when the vehicle steering devices 100 to 106 are configured using a processor. In this case, the function of each unit of the vehicle steering systems 100 to 106 is realized by a combination with software or the like (software, firmware, or software and firmware). The software and the like are described as programs and stored in the memory 112. The processor 111 that functions as the processing circuit 110 realizes the functions of the respective units by reading and executing the program stored in the memory 112 (storage device).

It should be noted that, in the present invention, the respective embodiments can be freely combined, or the respective embodiments can be appropriately modified or omitted within the scope of the invention.

1, 1A, 1B Vehicle, 50-55 Target steering angle calculation unit.

Claims (7)

A steering device for a vehicle, which performs steering control so that the vehicle automatically travels along a target traveling path of the vehicle,
A target travel locus calculation unit that calculates the target travel locus,
At least a calculation unit that calculates a target steering angle based on a curvature of the target traveling locus and a lateral deviation of the vehicle from the target traveling locus,
The arithmetic unit is
In a predetermined situation where a high traveling locus following accuracy is required, the target steering angle is calculated by increasing the feedback control gain used in the calculation of the target steering angle as compared with the case where the predetermined situation is not satisfied,
The predetermined situation is
In the situation where the lane change of the vehicle is instructed,
The calculation unit calculates the target steering angle by increasing the feedback control gain, as compared with a situation where a lane change is not instructed,
The target travel locus calculation unit,
A vehicle steering device that calculates the target travel locus based on the position and orientation of the vehicle obtained using road map data and satellite positioning information. A steering device for a vehicle, which performs steering control so that the vehicle automatically travels along a target traveling path of the vehicle,
A target travel locus calculation unit that calculates the target travel locus,
At least a calculation unit that calculates a target steering angle based on a curvature of the target traveling locus and a lateral deviation of the vehicle from the target traveling locus,
The arithmetic unit is
In a predetermined situation where a high traveling locus following accuracy is required, the target steering angle is calculated by increasing the feedback control gain used in the calculation of the target steering angle as compared with the case where the predetermined situation is not satisfied,
The predetermined situation is
When the lane width is narrower than the threshold,
The calculation unit calculates the target steering angle by increasing the feedback control gain as compared to a situation in which the traveling lane width is equal to or more than the threshold value.
The target travel locus calculation unit,
A vehicle steering system that calculates the target travel locus based on the position and azimuth of the vehicle obtained using road map data and satellite positioning information . A steering device for a vehicle, which performs steering control so that the vehicle automatically travels along a target traveling path of the vehicle,
A target travel locus calculation unit that calculates the target travel locus,
At least a calculation unit that calculates a target steering angle based on a curvature of the target traveling locus and a lateral deviation of the vehicle from the target traveling locus,
The arithmetic unit is
In a predetermined situation where a high traveling locus following accuracy is required, the target steering angle is calculated by increasing the feedback control gain used in the calculation of the target steering angle as compared with the case where the predetermined situation is not satisfied,
The predetermined situation is
In the situation where the vehicle is located before or after the toll collection point or within the toll collection point,
The calculation unit calculates the target steering angle by increasing the feedback control gain as compared with a situation in which the vehicle is not located before or after the toll collection point or within the toll collection point,
The target travel locus calculation unit,
A vehicle steering system that calculates the target travel locus based on the position and azimuth of the vehicle obtained using road map data and satellite positioning information . A steering device for a vehicle, which performs steering control so that the vehicle automatically travels along a target traveling path of the vehicle,
A target travel locus calculation unit that calculates the target travel locus,
At least a calculation unit that calculates a target steering angle based on a curvature of the target traveling locus and a lateral deviation of the vehicle from the target traveling locus,
The arithmetic unit is
In a predetermined situation where a high traveling locus following accuracy is required, the target steering angle is calculated by increasing the feedback control gain used in the calculation of the target steering angle as compared with the case where the predetermined situation is not satisfied,
The predetermined situation is
In a situation where there are other vehicles and obstacles around the vehicle,
The calculation unit calculates the target steering angle by increasing the feedback control gain as compared to a situation where the other vehicle and the obstacle do not exist around the vehicle.
The target travel locus calculation unit,
A vehicle steering system that calculates the target travel locus based on the position and azimuth of the vehicle obtained using road map data and satellite positioning information . The situation where the lane change of the vehicle is instructed is
The vehicle steering apparatus according to claim 1, wherein the lane change instruction switch provided on the vehicle is in an ON state. The information about the traveling lane width is
The vehicle steering system according to claim 2 , which is acquired from the road map data. Information on the toll collection point is
The vehicle steering system according to claim 3 , which is acquired from the road map data.

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