JP7338551B2 - Steering amount determination device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for causing a vehicle to follow a preceding vehicle.

Japanese Patent Laid-Open No. 2003-100002 discloses a technique for controlling the center position of the vehicle so that the center position of the vehicle in the vehicle width direction coincides with the center position of the preceding vehicle in the vehicle width direction when the vehicle is caused to follow the preceding vehicle. .

JP 2017-105250 A

When the center position of the preceding vehicle and the center position of the own vehicle are controlled to coincide with each other, when the preceding vehicle meanders, the own vehicle also meanders, resulting in the problem that the behavior of the own vehicle is unstable.

Accordingly, the present invention has been made in view of these points, and an object of the present invention is to stabilize the behavior of the own vehicle when the own vehicle is following the preceding vehicle.

In the aspect of the present invention, a distance specifying unit that specifies a distance from the own vehicle to the preceding vehicle in the width direction of the own vehicle at predetermined time intervals , and the distance newly specified by the distance specifying unit. a lateral speed calculation unit that calculates the absolute value of a value obtained by dividing the difference from the distance specified immediately before by the distance specifying unit by the time interval as the lateral speed of the preceding vehicle in the vehicle width direction ; When the vehicle width of the preceding vehicle detected from the captured image that is captured in the forward direction of the vehicle is less than or equal to a first coefficient change threshold that is set to be smaller as the vehicle width of the vehicle is narrower than the vehicle width of the vehicle, the lateral velocity is calculated. a first coefficient setting unit that increases a first coefficient to be multiplied by the first steering amount proportional to the lateral speed calculated by the first coefficient setting unit, and decreases the first coefficient when the distance is greater than the first coefficient change threshold; , if the lateral velocity is equal to or greater than a second coefficient change threshold value for determining whether or not to change a second coefficient to be multiplied by the second steering amount proportional to the distance specified by the distance specifying unit, then the second a second coefficient setting unit for increasing the coefficient and decreasing the second coefficient when the lateral speed is less than the second coefficient change threshold; A sum of a value obtained by multiplying the steering amount and a value obtained by multiplying the second steering amount by the second coefficient set by the second coefficient setting unit is a steering instruction for the own vehicle to follow the preceding vehicle. and a steering amount determining unit for determining the steering amount.

For example, the first coefficient setting unit increases the upper limit of the first coefficient when the lateral speed is equal to or greater than the upper limit change threshold, and increases the first coefficient when the lateral speed is less than the upper limit change threshold. Decrease the upper limit of

For example, when the distance is greater than the first coefficient change threshold and the distance is equal to or greater than a first coefficient decrease threshold that is greater than the first coefficient change threshold, the first coefficient setting unit sets the first coefficient to Make smaller.

For example, when the lateral speed is equal to or greater than the second coefficient change threshold and the lateral speed is equal to or greater than a second coefficient increase threshold, which is greater than the second coefficient change threshold, the second coefficient setting unit sets the 2 Increase the coefficient.

ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the behavior of the own vehicle can be stabilized.

It is a figure showing typically composition of a driving support system concerning an embodiment. It is a figure for demonstrating a distance and a lateral velocity. FIG. 10 is a diagram for explaining processing for increasing or decreasing the first coefficient kD according to changes in distance; FIG. 10 is a diagram for explaining processing for increasing or decreasing the upper limit value of the first coefficient kD according to the lateral speed; FIG. 10 is a diagram for explaining processing for increasing or decreasing the second coefficient kP according to changes in lateral velocity; FIG. 9 is a diagram for explaining processing for increasing or decreasing the lower limit value of the second coefficient kP according to the lateral speed; FIG. 4 is a diagram schematically showing a case where a preceding vehicle meanders; FIG. 4 is a diagram schematically showing a case in which a preceding vehicle enters a curve from a straight road; 9 is a flowchart showing an example of processing for setting a first coefficient kD; 9 is a flowchart showing an example of processing for setting a second coefficient kP; 9 is a flowchart showing an example of processing for setting the lower limit value of the second coefficient kP;

[Configuration of Driving Support System S]
FIG. 1 is a diagram schematically showing the configuration of a driving support system S according to an embodiment. A driving support system S installed in the own vehicle includes a steering amount determination device 1 , an imaging unit 2 , an automatic steering control device 3 , and a steering motor 4 . The image capturing unit 2 is a camera that captures an image of the forward direction of the own vehicle. The imaging unit 2 sequentially generates captured images in which the forward direction of the host vehicle is captured. The imaging unit 2 then outputs the generated captured image to the steering amount determination device 1 .

The steering amount determination device 1 detects the preceding vehicle included in the captured image generated by the imaging unit 2 . The steering amount determination device 1 determines a steering command amount, which is a steering amount that causes the own vehicle to follow the detected preceding vehicle. The steering amount determination device 1 determines a first steering amount δD that is proportional to the speed of the preceding vehicle in the vehicle width direction of the own vehicle, and a second steering amount δP that is proportional to the distance between the own vehicle and the preceding vehicle in the vehicle width direction. Calculate each. Then, the steering amount determination device 1 determines the sum of the value obtained by multiplying the first steering amount δD by the first coefficient kD and the value obtained by multiplying the second steering amount δP by the second coefficient kP as the steering command amount δreq. . Specifically, the steering amount determination device 1 calculates the steering command amount δreq using the following equation (1).
δreq=δD×kD+δP×kP (1)

By determining the steering instruction amount δreq, the behavior of the own vehicle following the preceding vehicle can be stabilized. A specific method for setting each of the first steering amount δD, the first coefficient kD, the second steering amount δP, and the second coefficient kP will be described later.

The automatic steering control device 3 controls the steering motor 4 so that the steering angle corresponds to the steering instruction amount δreq determined by the steering amount determination device 1 . Thus, the driving support system S can control the own vehicle to follow the preceding vehicle.

[Configuration of steering amount determination device 1]
The steering amount determination device 1 includes a storage section 11 and a control section 12 . The storage unit 11 is a storage medium including a ROM (Read Only Memory), a RAM (Random Access Memory), a hard disk, and the like. The storage unit 11 stores programs executed by the control unit 12 .

The control unit 12 is a computing resource including a processor such as a CPU (Central Processing Unit). By executing the programs stored in the storage unit 11, the control unit 12 functions as a distance specifying unit 121, a lateral speed calculating unit 122, a first coefficient setting unit 123, a second coefficient setting unit 124, and a steering amount determining unit 125. to realize the function of

The distance specifying unit 121 detects the preceding vehicle included in the captured image generated by the imaging unit 2 . The distance identification unit 121 sequentially identifies the distance from the own vehicle to the detected preceding vehicle. Specifically, the distance identification unit 121 sequentially identifies the distance from the own vehicle to the preceding vehicle in the vehicle width direction of the own vehicle at predetermined intervals. A specific value for the predetermined interval is, for example, 100 milliseconds.

The lateral speed calculator 122 calculates a lateral speed, which is the speed of the preceding vehicle in the vehicle width direction of the host vehicle. For example, the lateral speed calculator 122 calculates the lateral speed of the preceding vehicle based on the change in the distance specified by the distance specifying unit 121 . Specifically, lateral velocity calculation section 122 calculates the absolute value of the difference between the distance newly specified by distance specifying section 121 and the distance specified immediately before by distance specifying section 121 by a predetermined interval. Identify as

FIG. 2 is a diagram for explaining the distance L and the lateral velocity Vy. In FIG. 2, it is assumed that host vehicle A and preceding vehicle B are traveling on a straight road. An arrow Y indicates the vehicle width direction of the host vehicle A. As shown in FIG. The position F is the center position of the vehicle A in the vehicle width direction. Distance L indicates the distance from the center position of own vehicle A to the center position of the preceding vehicle in the vehicle width direction. The lateral velocity Vy is a vector indicating the velocity of the preceding vehicle B in the vehicle width direction.

A first coefficient setting unit 123 sets a first coefficient kD by which the first steering amount δD is multiplied. For example, as shown in FIG. 2, the first coefficient setting unit 123 increases the first coefficient kD by which the first steering amount δD is multiplied when the distance L specified by the distance specifying unit 121 is equal to or smaller than the first coefficient change threshold value P1. do. Specifically, the first coefficient setting unit 123 sets the value obtained by counting the time during which the distance L is equal to or less than the first coefficient change threshold value P1 as the first count value for setting the first coefficient kD. to add. Then, the first coefficient setting unit 123 sets a value obtained by multiplying the first count value by a predetermined first conversion value as the first coefficient kD.

Note that the first coefficient setting unit 123 may set the first coefficient change threshold value P1 smaller as the vehicle width of the preceding vehicle B is narrower than the vehicle width of the own vehicle A. Specifically, the first coefficient setting unit 123 decreases the first coefficient change threshold value P1 as the difference obtained by subtracting the vehicle width of the preceding vehicle B from the vehicle width of the own vehicle A increases. Further, the first coefficient setting unit 123 decreases the first coefficient change threshold value P1 as the ratio of the vehicle width of the preceding vehicle B to the vehicle width of the host vehicle A is smaller. The first coefficient change threshold P1 may be predetermined, and a specific value is, for example, 1.5 meters. The first conversion value may be appropriately determined through experiments or the like.

By doing so, when the distance L between the own vehicle A and the preceding vehicle B is small, the first coefficient setting unit 123 sets the value obtained by multiplying the first steering amount δD, which is proportional to the lateral speed Vy, by the first coefficient kD. can be increased, the steering instruction amount δreq can be quickly increased when the lateral velocity Vy of the preceding vehicle B increases. As a result, the first coefficient setting unit 123 can enhance the responsiveness to the movement of the preceding vehicle B in the vehicle width direction. Therefore, the first coefficient setting unit 123 makes it easier for the vehicle A to follow the movement of the preceding vehicle B when the preceding vehicle B moves in the vehicle width direction to avoid an obstacle on the road. You can enhance your sexuality.

The first coefficient setting unit 123 reduces the first coefficient kD when the distance L is greater than the first coefficient change threshold value P1. For example, the first coefficient setting unit 123 reduces the first coefficient kD when the distance L is equal to or greater than a first coefficient decrease threshold that is larger than the first coefficient change threshold P1. Specifically, the first coefficient setting unit 123 subtracts from the first count value a value obtained by counting the duration of the state equal to or greater than the first coefficient decrease threshold. Also, the first coefficient setting unit 123 does not change the first coefficient kD when the distance L is greater than the first coefficient change threshold value P1 and less than the first coefficient decrease threshold value. The first coefficient decrease threshold may be determined in the same manner as the first coefficient change threshold P1, or may be appropriately determined through experiments or the like. A specific value for the first factor reduction threshold is, for example, 2.0 meters.

In this way, when the distance L between the own vehicle A and the preceding vehicle B is large, the first coefficient setting unit 123 reduces the value obtained by multiplying the first steering amount δD, which is proportional to the lateral speed Vy, by the first coefficient kD. . Therefore, the first coefficient setting unit 123 can prevent the steering command amount δreq from becoming too large in a situation where the lateral speed Vy increases while the distance L is large (for example, when entering a straight road from a curve).

3A and 3B are diagrams for explaining the process of increasing or decreasing the first coefficient kD according to the distance L. FIG. FIG. 3(a) is a graph schematically showing the temporal change of the distance L from the host vehicle A to the preceding vehicle B. FIG. The horizontal axis of FIG. 3(a) indicates the time t, and the vertical axis indicates the magnitude of the distance L. As shown in FIG. A dashed line in FIG. 3A indicates the first coefficient change threshold value P1, and a two-dot chain line indicates the first coefficient decrease threshold value P2. FIG. 3B is a diagram schematically showing temporal changes in the first coefficient kD. The horizontal axis of FIG. 3B indicates the time t, and the vertical axis indicates the magnitude of the first coefficient kD. The dashed line in FIG. 3(b) indicates the upper limit value M of the first coefficient kD.

The first coefficient setting unit 123 counts the time (from time t0 to time t11) during which the distance L is equal to or less than the first coefficient change threshold value P1. The first coefficient setting unit 123 adds the value obtained by counting the number of states in which the distance L is equal to or less than the first coefficient change threshold value P1 to the first count value for setting the first coefficient kD. The first coefficient setting unit 123 sets a value obtained by multiplying the first count value by a predetermined coefficient as the first coefficient kD. As shown in FIG. 3B, from time t0 to time t11, the distance L continues to be equal to or less than the first coefficient change threshold value P1, so the first coefficient kD increases.

When the distance L increases and becomes larger than the first coefficient change threshold value P1, the first coefficient setting unit 123 does not count the duration of the state. Specifically, the first coefficient setting unit 123 determines the length of time (from time t11 to time t12) during which the distance L is greater than the first coefficient change threshold value P1 and less than the first coefficient decrease threshold value P2. don't count. As shown in FIG. 3B, from time t11 to time t12, the distance L continues to be greater than the first coefficient change threshold value P1 and less than the first coefficient decrease threshold value P2. The coefficient kD is constant.

When the distance L further increases and becomes equal to or greater than the first coefficient decrease threshold value P2, the first coefficient setting unit 123 determines the length of time during which the distance L remains equal to or greater than the first coefficient decrease threshold value P2 (from time t12 to t13). between) are counted. Then, the first coefficient setting unit 123 subtracts from the first count value a value obtained by counting the time during which the distance L has continued to be equal to or greater than the first coefficient decrease threshold value P2, and converts the first count value into a first coefficient kD. do. As shown in FIG. 3B, the distance L continues to be equal to or greater than the first coefficient decrease threshold value P2 from time t12 to t13, so the first coefficient kD decreases.

Note that the first coefficient setting unit 123 sets the first coefficient kD to the same value as the lower limit of the first coefficient kD when the first coefficient kD is equal to or lower than the lower limit of the first coefficient kD. The lower limit of the first coefficient kD is zero.

When the distance L decreases to become equal to or less than the first coefficient change threshold value P1 (after time t14), the first coefficient setting unit 123 counts the time during which the distance L continues to be equal to or less than the first coefficient change threshold value P1. . The first coefficient setting unit 123 adds a value obtained by counting the time during which the distance L is equal to or less than the first coefficient change threshold value P1 to the first count value, and multiplies the first count value by a predetermined coefficient. It is set as the first coefficient kD. As shown in FIG. 3B, after time t14, the distance L continues to be equal to or less than the first coefficient change threshold value P1, so the first coefficient kD increases.

The first coefficient setting unit 123 sets the first coefficient kD to the same value as the upper limit M when the first coefficient kD obtained by converting the first count value is greater than or equal to the upper limit M of the first coefficient kD. As shown in FIG. 3B, the first coefficient kD is constant at the upper limit value M after time t15.

By the way, if the first coefficient kD is made too large, the steering instruction amount δreq becomes too large. Therefore, the first coefficient setting unit 123 sets the upper limit value for increasing the first coefficient kD according to the lateral speed Vy of the preceding vehicle B. FIG. For example, the first coefficient setting unit 123 reduces the upper limit value of the first coefficient kD when the lateral speed Vy of the preceding vehicle B is less than the upper limit change threshold. Specifically, first coefficient setting unit 123 decreases the upper limit value in proportion to the time during which lateral velocity Vy remains below the upper limit change threshold value. The upper limit change threshold may be appropriately determined through experiments or the like. A specific value of the upper limit change threshold is, for example, 0.05 to 0.5 meters per second. By decreasing the upper limit value, the first coefficient setting unit 123 can prevent the steering instruction amount δreq from becoming too large.

Further, first coefficient setting unit 123 increases the upper limit value of first coefficient kD when lateral velocity Vy of the preceding vehicle is equal to or greater than the upper limit change threshold value. For example, the first coefficient setting unit 123 increases the upper limit value of the first coefficient kD in proportion to the time during which the state equal to or above the upper limit value change threshold has continued. Note that the maximum value is set as the upper limit value of the first coefficient kD, and the maximum value is not changed.

FIG. 4 is a diagram for explaining the process of increasing or decreasing the upper limit value M of the first coefficient kD according to the lateral velocity Vy. FIG. 4(a) is a graph schematically showing temporal changes in lateral velocity Vy. The horizontal axis of FIG. 4(a) indicates the time t, and the vertical axis indicates the magnitude of the lateral velocity Vy. A dashed line in FIG. 4A indicates the upper limit value change threshold value G. FIG. 4(b) is a diagram schematically showing temporal changes in the upper limit value M. As shown in FIG. The horizontal axis of FIG. 4(b) indicates the time t, and the vertical axis indicates the magnitude of the upper limit M. As shown in FIG. 4B indicates the maximum value Mmax of the upper limit value M, and the two-dot chain line indicates the minimum value Mmin of the upper limit value M. In FIG.

First coefficient setting unit 123 decreases upper limit value M while lateral velocity Vy is less than upper limit value change threshold value G continues. At this time, the first coefficient setting unit 123 sets the upper limit value M to the same value as the minimum value Mmin when the upper limit value M becomes equal to or less than the minimum value Mmin. As shown in FIG. 4B, from time t0 to time t21, the lateral velocity Vy continues to be less than the upper limit value change threshold value G, but the upper limit value M of the first coefficient kD is the minimum value Mmin. is constant at .

The first coefficient setting unit 123 counts the time (from time t21 to time t22) during which the lateral velocity Vy remains equal to or greater than the upper limit value change threshold G. The first coefficient setting unit 123 adds the value obtained by counting the number of times the lateral velocity Vy is equal to or greater than the upper limit value change threshold value G to the value for setting the upper limit value M. First coefficient setting unit 123 sets upper limit M to a value obtained by multiplying a value for setting upper limit M by a predetermined coefficient. As shown in FIG. 4B, from time t21 to time t23, the lateral velocity Vy continues to be equal to or greater than the upper limit value change threshold value G, so the upper limit value M increases.

When the upper limit value M increases to reach the maximum value Mmax of the upper limit value M, the first coefficient setting unit 123 sets the upper limit value M to the same value as the maximum value Mmax. As shown in FIG. 4B, the upper limit M is constant at the maximum value Mmax from time t23 to time t22.

The first coefficient setting unit 123 reduces the upper limit value M when the lateral velocity Vy decreases and becomes less than the upper limit change threshold value G. FIG. As shown in FIG. 4B, the upper limit value M decreases from time t22 to time t24. When the upper limit value M becomes the minimum value Mmin of the upper limit value M, the first coefficient setting unit 123 sets the upper limit value M to the same value as the minimum value Mmin. As shown in FIG. 4B, the upper limit value M is constant at the minimum value Mmin after time t24.

The process of setting the first coefficient kD by the first coefficient setting unit 123 has been described above. Next, the process of setting the second coefficient kP by the second coefficient setting unit 124 will be described.

[Processing for Setting Second Coefficient kP]
A second coefficient setting unit 124 sets a second coefficient kP by which the second steering amount δP is multiplied. For example, second coefficient setting unit 124 increases the second coefficient by which second steering amount δP is multiplied when lateral speed Vy specified by lateral speed calculating unit 122 is equal to or greater than the second coefficient change threshold. Specifically, second coefficient setting unit 124 increases second coefficient kP when lateral velocity Vy is greater than or equal to a second coefficient increase threshold that is greater than the second coefficient change threshold. More specifically, the second coefficient setting unit 124 adds the value obtained by counting the time during which the second coefficient increase threshold value or more continues to the second count value for setting the second coefficient kP. Then, the second coefficient setting unit 124 sets a value obtained by multiplying the second count value by a predetermined second conversion value as the second coefficient kP. The second coefficient change threshold, the second coefficient increase threshold, and the second conversion value may be appropriately set through experiments or the like. A specific value for the second modulus change threshold is, for example, 0.1 meters per second. A specific value for the second coefficient increase threshold is, for example, 0.2 meters per second.

By doing so, the second coefficient setting unit 124 can set the second coefficient proportional to the distance L in a situation where the lateral velocity Vy is expected to increase and the distance L is expected to increase (for example, when entering a curve). A value obtained by multiplying the steering amount δP by the second coefficient kP can be increased. As a result, the second coefficient setting unit 124 can suppress an increase in the distance L from the own vehicle A to the preceding vehicle B, and the ability of the own vehicle A to follow the preceding vehicle B can be enhanced.

Second coefficient setting unit 124 reduces second coefficient kP when lateral velocity Vy is less than the second coefficient change threshold. For example, the second coefficient setting unit 124 reduces the second coefficient kP by subtracting from the second count value the value obtained by counting the time that the lateral velocity Vy has continued to be less than the second coefficient change threshold value.

By doing so, the second coefficient setting unit 124 can substantially reduce the second steering amount δP proportional to the distance L when the lateral velocity Vy is less than the second coefficient change threshold. Therefore, the second coefficient setting unit 124 can prevent the steering command amount δreq from increasing even if the distance L increases. As a result, the second coefficient setting unit 124 can prevent the steering angle from becoming unnecessarily large while following the preceding vehicle B while traveling on a curve. Further, the second coefficient setting unit 124 can prevent following the preceding vehicle B even if it meanders while traveling on a straight road, so the behavior of the own vehicle A can be stabilized.

FIG. 5 is a diagram for explaining the process of increasing or decreasing the second coefficient kP according to the lateral velocity Vy. FIG. 5(a) is a graph schematically showing temporal changes in the lateral velocity Vy of the preceding vehicle B. FIG. The horizontal axis of FIG. 5(a) indicates the time t, and the vertical axis indicates the lateral velocity Vy. A dashed line in FIG. 5A indicates the second coefficient change threshold value N. As shown in FIG. FIG. 5(b) is a diagram schematically showing the temporal change of the second coefficient kP. The horizontal axis of FIG. 5B indicates the time t, and the vertical axis indicates the magnitude of the second coefficient kP. The dashed line in FIG. 5(b) indicates the upper limit value C of the second coefficient kP.

Second coefficient setting unit 124 does not change second coefficient kP while lateral velocity Vy continues to be less than second coefficient change threshold value N (from time t0 to t31). As shown in FIG. 5(b), from time t0 to t31, the lateral velocity Vy continues to be less than the second coefficient change threshold value N, so the second coefficient kP is constant.

When the lateral velocity Vy increases to become equal to or greater than the second coefficient change threshold value N, the second coefficient setting unit 124 sets the time during which the lateral velocity Vy remains equal to or greater than the second coefficient change threshold value N (from time 21 to t32). between) are counted. Then, second coefficient setting unit 124 adds a value obtained by counting the time during which lateral velocity Vy continues to be equal to or greater than second coefficient change threshold value N to the second count value, and sets the second count value to second coefficient kP. Convert. As shown in FIG. 5B, from time t31 to time t33, the lateral velocity Vy increases and remains equal to or higher than the second coefficient change threshold value N, so the second coefficient kP increases. .

Second coefficient setting unit 124 sets second coefficient kP to Set to the same value as upper limit C. A specific value of the upper limit value C of the second coefficient kP is 1, for example. As shown in FIG. 5B, the second coefficient kP is constant at the upper limit value C after time t33.

When the lateral speed Vy decreases and becomes less than the second coefficient change threshold value N (after time t32), the second coefficient setting unit 124 sets the time during which the lateral speed Vy has remained less than the second coefficient change threshold value N. count. Then, second coefficient setting unit 124 subtracts from the second count value the value obtained by counting the time during which lateral velocity Vy has continued to be less than second coefficient change threshold value N, and sets the second count value to second coefficient kP. Convert. As shown in FIG. 5(b), the second coefficient kP decreases after time t32.

When the second coefficient kP reaches the lower limit set based on the distance L and the lateral velocity Vy, the second coefficient setting unit 124 sets the second coefficient kP to the same value as the lower limit of the second coefficient kP. do. Note that the lower limit of the second coefficient kP is zero.

The second coefficient setting unit 124 may set the lower limit value of the second coefficient kP based on the lateral velocity Vy and the distance L. For example, when the distance L is greater than the distance determination threshold, the second coefficient setting unit 124 sets the lower limit of the second coefficient kP to the same value as the upper limit of the second coefficient kP. By doing so, the second coefficient setting unit 124 can increase the steering instruction amount δreq when the distance L increases, so that the own vehicle A can follow the traveling locus of the preceding vehicle B. It should be noted that the distance determination threshold value may be appropriately set through experiments or the like so as to suppress shortcuts in the trajectory when following a vehicle with a relatively long distance from host vehicle A to preceding vehicle B. A value of less than 50 meters is desirable for the distance determination value.

The second coefficient setting unit 124 increases or decreases the lower limit value of the second coefficient kP according to the magnitude of the lateral velocity Vy when the distance L is equal to or less than the distance determination threshold. Specifically, the second coefficient setting unit 124 increases the lower limit value of the second coefficient kP when the distance L is equal to or less than the distance determination threshold and when the lateral velocity Vy is equal to or more than the lower limit change threshold. The lower limit value change threshold may be appropriately set through experiments or the like, and a specific value is, for example, 0.05 meters per second. Note that the lower limit change threshold and the second coefficient change threshold N may be the same value.

By doing so, the second coefficient setting unit 124 can prevent the steering instruction amount δreq from becoming too small when the lateral velocity Vy is relatively high, so that the followability of the own vehicle A can be improved. Further, second coefficient setting unit 124 reduces the lower limit value of second coefficient kP when lateral velocity Vy is less than the lower limit value change threshold. By doing so, the second coefficient setting unit 124 can reduce the steering instruction amount δreq when the lateral velocity Vy is relatively small, and can prevent unnecessary steering.

FIG. 6 is a diagram for explaining the process of increasing or decreasing the lower limit value I of the second coefficient kP according to the lateral velocity Vy. FIG. 6(a) is a graph schematically showing temporal changes in lateral velocity Vy. The horizontal axis of FIG. 6(a) indicates the time t, and the vertical axis indicates the lateral velocity Vy. A dashed line in FIG. 6A indicates the lower limit change threshold value H. FIG. FIG. 6(b) is a diagram schematically showing changes in the lower limit value I over time. The horizontal axis of FIG. 6(b) indicates the time t, and the vertical axis indicates the magnitude of the lower limit value I. As shown in FIG. A dashed line in FIG. 6B indicates the upper limit value C of the second coefficient kP. The upper limit value C is the maximum value of the lower limit value I. In addition, in FIG. 6, the distance L is equal to or less than the distance determination threshold value E from the time t0 to the time t42. Also, the distance L is assumed to be greater than the distance determination threshold E after time t42.

Second coefficient setting unit 124 increases lower limit value I while lateral velocity Vy remains below lower limit value change threshold value H (from time t0 to t41). Specifically, second coefficient setting unit 124 counts the time (from time t0 to time t41) during which lateral velocity Vy has remained below lower limit change threshold value H. FIG. Next, the second coefficient setting unit 124 adds the value obtained by counting the time during which the lateral velocity Vy has remained below the lower limit value change threshold value H to the value for setting the lower limit value I. Then, the second coefficient setting unit 124 converts the value for setting the lower limit value I into the lower limit value I. FIG.

In addition, the second coefficient setting unit 124 sets the lower limit value I to the same value as the upper limit value C when the lower limit value I becomes the upper limit value C. As shown in FIG. 6B, the lower limit value I increases from time t0 to time t43, and remains constant at the upper limit value C from time t43 to t41.

Second coefficient setting unit 124 reduces lower limit value I when lateral velocity Vy increases and becomes equal to or higher than lower limit value change threshold value H. FIG. For example, the second coefficient setting unit 124 counts the time (between time 41 and time t42) during which the lateral velocity Vy has remained equal to or higher than the lower limit value change threshold value H, and sets the value for setting the lower limit value I. Subtract from As shown in FIG. 6B, from time t41 to time t42, the lateral velocity Vy continues to be equal to or higher than the lower limit value change threshold value H, so the lower limit value I is decreasing.

Second coefficient setting unit 124 sets lower limit value I to 0 when lower limit value I decreases to 0 or less (time t43). As shown in FIG. 5B, the lower limit I is constant at 0 from time t43 to t42.

When the lateral velocity Vy decreases to become less than the lower limit change threshold value H (after time t42), the second coefficient setting unit 124 counts the time during which the lateral velocity Vy has remained less than the lower limit change threshold value H. . Then, the second coefficient setting unit 124 adds to the second count value a value obtained by counting the time during which the lateral velocity Vy has continued to be less than the lower limit value change threshold value H, and converts the second count value into the lower limit value I. . As shown in FIG. 6B, the lower limit value I increases from time t42 to time t45.

The second coefficient setting unit 124 sets the lower limit value I to the same value as the upper limit value C when the distance L is greater than the distance determination threshold E. As shown in FIG. 6B, the lower limit value I and the upper limit value C are the same at time t45 when the distance L becomes greater than the distance determination threshold E.

The steering amount determination unit 125 determines the steering amount so that the host vehicle A follows the travel locus of the preceding vehicle B based on the distance L and the lateral velocity Vy. Specifically, first, the steering amount determination unit 125 determines a first steering amount δD proportional to the lateral speed Vy calculated by the lateral speed calculation unit 122 and a second steering amount proportional to the distance L specified by the distance specifying unit 121. Calculate the quantity δP. For example, the steering amount determination unit 125 calculates the second steering amount δP proportional to the distance L using the Pure Pursuit method, which is a known steering amount calculation method. Further, the steering amount determination unit 125 can calculate the first steering amount δD proportional to the lateral velocity Vy by replacing the distance L with the lateral velocity Vy in the Pure Pursuit method.

Then, the steering amount determination unit 125 multiplies the first steering amount δD by the first coefficient kD set by the first coefficient setting unit 123, and the second coefficient kP set by the second coefficient setting unit 124 described later. The sum of the value obtained by multiplying the second steering amount .delta.P is determined as the steering instruction amount .delta.req. Specifically, the steering amount determination unit 125 calculates the steering instruction amount δreq using the above-described formula (1).

(When preceding vehicle B meanders while traveling on a straight road)
The preceding vehicle B may meander while traveling on a straight road. By setting the first coefficient kD and the second coefficient kP based on the distance L and the lateral velocity Vy, the steering amount determination device 1 prevents the vehicle A from meandering even if the preceding vehicle B meanders. can be suppressed. FIG. 7 is a diagram schematically showing a case where the preceding vehicle B meanders. In FIG. 7, a half-broken line RA indicates the travel locus of the own vehicle A. In FIG. A dashed line RB indicates the travel locus of the preceding vehicle B. As shown in FIG. Note that the distance L from the own vehicle A to the preceding vehicle B shown in FIG. 7 is greater than the first coefficient reduction threshold value P2.

When the preceding vehicle B travels near the outside line of the lane while meandering, the distance L increases and the lateral speed Vy decreases. In this case, the first coefficient setting unit 123 reduces the first coefficient kD, and the second coefficient setting unit 124 reduces the second coefficient kP. As a result, the steering instruction amount δreq determined by the steering amount determining unit 125 becomes smaller, so the own vehicle A travels along a trajectory such that the amplitude HB of the travel trajectory of the preceding vehicle B is reduced. Therefore, the amplitude HA of the trajectory of the host vehicle A is smaller than the amplitude HB of the trajectory of the preceding vehicle B.

(When preceding vehicle B enters a curve)
The known Pure Pursuit method determines the steering angle based on the distance L between the own vehicle A and the preceding vehicle B. Therefore, when determining the steering amount of the own vehicle A using the Pure Pursuit method, the steering amount of the own vehicle A is increased after the preceding vehicle B enters the clothoid section of the curve and the distance L increases. As a result, a delay occurs before the steering amount necessary for following the preceding vehicle B is set. In the conventional Pure Pursuit method, the steering amount may fluctuate in such a way that the steering amount is increased by the amount of the delay that has occurred, and the steering amount is decreased by the amount of excessively increased steering amount.

The steering amount determination device 1 according to the embodiment calculates a first coefficient kD by which a first steering amount δD proportional to the lateral speed Vy is multiplied when the distance L between the own vehicle A and the preceding vehicle B is small while traveling on a straight road. increases. Therefore, the steering amount determination device 1 can quickly follow the own vehicle A when the preceding vehicle B moves in the vehicle width direction (that is, when the lateral speed Vy of the preceding vehicle B increases). FIG. 8 is a diagram schematically showing a case where preceding vehicle B enters a curve from a straight road. In FIG. 8, the distance L is assumed to be smaller than the first coefficient change threshold P1 and smaller than the distance determination threshold E. In FIG. It is also assumed that the lateral velocity Vy is greater than the second coefficient change threshold value N. FIG.

As shown in FIG. 8, when the distance L is small and the lateral speed Vy is large, the steering amount determination device 1 sets the first coefficient kD by which the first steering amount δD proportional to the lateral speed Vy is multiplied, and the distance L as The second coefficient kP by which the proportional second steering amount δP is multiplied is increased. As a result, the steering amount determination device 1 can quickly increase the steering instruction amount δreq, so that the movement of the preceding vehicle B in the vehicle width direction can be easily followed. By doing so, the steering amount determining device 1 can suppress the steering amount from fluctuating, and the behavior of the own vehicle A can be stabilized.

[Flow of processing for setting the first coefficient kD]
FIG. 9 is a flowchart showing an example of processing for setting the first coefficient kD. First, the distance specifying unit 121 detects the preceding vehicle B included in the captured image generated by the imaging unit 2 . Subsequently, the distance identifying unit 121 sequentially identifies the distance L from the own vehicle A to the preceding vehicle B in the vehicle width direction of the own vehicle A (step S1). Next, the lateral speed calculation unit 122 calculates the lateral speed Vy of the preceding vehicle B based on the change in the distance L specified by the distance specifying unit 121 (step S2).

Subsequently, the first coefficient setting unit 123 executes processing for setting the upper limit value M of the first coefficient kD. First, the first coefficient setting unit 123 determines whether or not the lateral speed Vy calculated by the lateral speed calculating unit 122 is equal to or greater than the upper limit change threshold (step S3). When the lateral velocity Vy is equal to or greater than the upper limit change threshold (Yes in step S3), the first coefficient setting unit 123 increases the upper limit M of the first coefficient kD (step S4). When the lateral velocity Vy is less than the upper limit value change threshold (No in step S3), the first coefficient setting unit 123 reduces the upper limit value M of the first coefficient kD (step S5). Thus, the first coefficient setting unit 123 sets the upper limit value M according to the determination result of whether or not the lateral velocity Vy is equal to or greater than the upper limit change threshold value.

After setting the upper limit value M of the first coefficient kD, the first coefficient setting unit 123 determines whether or not the distance L is equal to or less than the first coefficient change threshold value P1 (step S6). When the distance L is equal to or less than the first coefficient change threshold value P1 (Yes in step S6), the first coefficient setting unit 123 increases the first coefficient kD until it reaches the set upper limit value M (step S7). For example, the first coefficient setting unit 123 adds a value obtained by counting the time during which the distance L is equal to or less than the first coefficient change threshold value P1 to the first count value, and converts the first count value to a predetermined first conversion value. The value multiplied by the value is set as the first coefficient kD (see FIG. 3(b)).

When the distance L is greater than the first coefficient change threshold value P1 (No in step S6), the first coefficient setting unit 123 determines whether or not the distance L is greater than or equal to the first coefficient decrease threshold value P2 (step S8). When the distance L is equal to or greater than the first coefficient decrease threshold value P2 (Yes in step S8), the first coefficient setting unit 123 decreases the first coefficient kD until it reaches the lower limit (0) of the first coefficient kD (step S9 ). Specifically, the first coefficient setting unit 123 subtracts from the first count value a value obtained by counting the time period during which the distance L is equal to or less than the first coefficient decrease threshold value P2, and sets the first count value to a predetermined value. A value obtained by multiplying the first conversion value is set as the first coefficient kD (see FIG. 3(b)).

When the distance L is smaller than the first coefficient decrease threshold value P2 (No in step S8), the first coefficient setting unit 123 does not change the first count value, and multiplies the first count value by a predetermined first conversion value. The value obtained is set as the first coefficient kD. The first coefficient setting unit 123 repeatedly executes the above process while the own vehicle A is following the preceding vehicle B.

[Flow of processing for setting the second coefficient kP]
FIG. 10 is a flowchart showing an example of processing for setting the second coefficient kP. The second coefficient setting unit 124 executes the series of processes shown in FIG. 10 at the same timing as the setting processing of the first coefficient kD performed by the first coefficient setting unit 123 . Steps S1 and S2 are the same as the processing described using FIG.

The second coefficient setting unit 124 executes processing for setting the lower limit value of the second coefficient kP (step S11). FIG. 11 is a flowchart showing an example of processing for setting the lower limit value of the second coefficient kP.

First, the second coefficient setting unit 124 determines whether or not the distance L specified by the distance specifying unit 121 is equal to or less than the distance determination threshold value E (step S21). When the distance L is equal to or less than the distance determination threshold value E (Yes in step S21), the second coefficient setting unit 124 determines whether the lateral speed Vy calculated by the lateral speed calculation unit 122 is equal to or greater than the lower limit change threshold value ( step S22).

Second coefficient setting unit 124 decreases the lower limit value of second coefficient kP when lateral velocity Vy is equal to or greater than the lower limit change threshold value (Yes in step S22). For example, the second coefficient setting unit 124 decreases the lower limit value of the second coefficient kP according to the duration that the lateral velocity Vy remains equal to or higher than the lower limit change threshold value (step S23). For example, the second coefficient setting unit 124 subtracts from the second count value a value obtained by counting the time that the lateral velocity Vy continues to be equal to or greater than the lower limit value change threshold, and sets the second count value to a predetermined second conversion value. is set as the second coefficient kP (see FIG. 6(b)).

If lateral velocity Vy is less than the lower limit change threshold (No in step S22), second coefficient setting unit 124 increases the lower limit of second coefficient kP (step S24). Specifically, second coefficient setting unit 124 increases the lower limit value according to the length of time that lateral velocity Vy remains below the lower limit change threshold value. More specifically, second coefficient setting unit 124 adds to the second count value a value obtained by counting the time period during which lateral velocity Vy is less than the lower limit value change threshold, and adds a predetermined value to the second count value. A value obtained by multiplying the second conversion value is set as the second coefficient kP (see FIG. 6B).

When the distance L is greater than the distance determination threshold value E (No in step S21), the second coefficient setting unit 124 sets the lower limit value of the second coefficient kP to the same value as the upper limit value of the second coefficient kP (step S25 ). Specifically, when the distance L is greater than the distance determination threshold value E, the second coefficient setting unit 124 sets the lower limit value of the second coefficient kP to 1, which is the upper limit value of the second coefficient kP (see FIG. 6 ( b)).

After setting the lower limit value of the second coefficient kP, the second coefficient setting unit 124 determines whether or not the lateral velocity Vy is greater than or equal to the second coefficient change threshold (step S12). When lateral velocity Vy is equal to or greater than the second coefficient change threshold (Yes in step S12), second coefficient setting unit 124 determines whether lateral velocity Vy is equal to or greater than a second coefficient increase threshold that is greater than the second coefficient change threshold. (step S13).

Second coefficient setting unit 124 increases second coefficient kP when lateral velocity Vy is greater than or equal to the second coefficient increase threshold (Yes in step S13). For example, the second coefficient setting unit 124 increases the second coefficient kP according to the duration of the state in which the lateral velocity Vy is equal to or greater than the second coefficient increase threshold (see (b) in FIG. 5). Second coefficient setting unit 124 does not change second coefficient kP when lateral velocity Vy is less than the second coefficient increase threshold (No in step S13).

Second coefficient setting unit 124 decreases second coefficient kP when lateral velocity Vy is less than the second coefficient change threshold value (No in step S12). Specifically, the second coefficient setting unit 124 decreases the second coefficient kP according to the length of time that the lateral velocity Vy remains below the second coefficient change threshold value (see (b) in FIG. 5). The second coefficient setting unit 124 repeatedly executes the above process while the own vehicle A is following the preceding vehicle B.

[Effect of driving support system S according to embodiment]
As described above, first, the steering amount determination device 1 sequentially identifies the distance L from the vehicle A to the preceding vehicle B in the vehicle width direction of the vehicle A, and based on the change in the identified distance L, A lateral velocity Vy of the preceding vehicle B in the width direction is calculated. Next, when the distance L is equal to or less than the first coefficient change threshold value P1, the steering amount determination device 1 increases the first coefficient kD by which the first steering amount δD proportional to the lateral velocity Vy is multiplied, and the distance L becomes the first coefficient. If it is greater than the change threshold value P1, the first coefficient kD is decreased. Further, when the lateral speed Vy is equal to or greater than the second coefficient change threshold, the steering amount determination device 1 increases the second coefficient kP by which the second steering amount δP that is proportional to the distance L is multiplied, and the lateral speed Vy is changed by the second coefficient. If it is less than the threshold, the second coefficient kP is decreased. Then, the steering amount determination device 1 calculates the sum of the value obtained by multiplying the first steering amount δD by the set first coefficient kD and the value obtained by multiplying the second steering amount δP by the set second coefficient kP as the steering command amount. δreq.

Thus, the steering amount determination device 1 sets each of the first coefficient kD and the second coefficient kP according to the situation. By doing so, the steering amount determination device 1 calculates the value obtained by multiplying the first steering amount δD proportional to the lateral velocity Vy by the first coefficient kD, and the second steering amount δP proportional to the distance L by the second coefficient Since the value multiplied by kP can be set according to the situation, the steering instruction amount δreq can be determined according to the situation. As a result, even if the preceding vehicle B meanders, the steering amount determination device 1 can suppress the vehicle A from following the trajectory of the preceding vehicle B, thereby stabilizing the behavior of the vehicle A. . Further, the steering amount determination device 1 can suppress the fluctuation of the steering amount of the own vehicle A when, for example, the preceding vehicle B enters a curve from a straight road, so that the behavior of the own vehicle A can be stabilized.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist thereof. be. For example, all or part of the device can be functionally or physically distributed and integrated in arbitrary units. In addition, new embodiments resulting from arbitrary combinations of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment caused by the combination has the effect of the original embodiment.

1 steering amount determination device 11 storage unit 12 control unit 121 distance determination unit 122 lateral speed calculation unit 123 first coefficient setting unit 124 second coefficient setting unit 125 steering amount determination unit 2 imaging unit 3 automatic steering control device 4 steering motor

Claims (4)

a distance identifying unit that identifies , at predetermined time intervals , a distance from the own vehicle to a preceding vehicle in the vehicle width direction of the own vehicle;
The absolute value of the difference between the distance newly specified by the distance specifying unit and the distance specified immediately before by the distance specifying unit is divided by the time interval as the lateral speed of the preceding vehicle in the vehicle width direction. a lateral velocity calculator that calculates
When the distance is less than or equal to a first coefficient change threshold that is set to be smaller as the vehicle width of the preceding vehicle detected from an image captured in front of the own vehicle in the traveling direction is narrower than the vehicle width of the own vehicle, A first coefficient to be multiplied by the first steering amount proportional to the lateral speed calculated by the lateral speed calculator is increased, and when the distance is greater than the first coefficient change threshold, the first coefficient is decreased. a coefficient setting unit;
When the lateral speed is equal to or greater than a second coefficient change threshold for determining whether or not to change a second coefficient to be multiplied by the second steering amount proportional to the distance specified by the distance specifying unit, the second coefficient a second coefficient setting unit that increases the second coefficient and decreases the second coefficient when the lateral speed is less than the second coefficient change threshold;
A value obtained by multiplying the first steering amount by the first coefficient set by the first coefficient setting section, and a value obtained by multiplying the second steering amount by the second coefficient set by the second coefficient setting section. a steering amount determination unit that determines the sum as a steering instruction amount for the own vehicle to follow the preceding vehicle ;
A steering amount determination device having The first coefficient setting unit increases the upper limit of the first coefficient when the lateral speed is equal to or greater than the upper limit change threshold, and increases the upper limit of the first coefficient when the lateral speed is less than the upper limit change threshold. decrease the value,
The steering amount determination device according to claim 1. The first coefficient setting unit reduces the first coefficient when the distance is greater than the first coefficient change threshold and the distance is equal to or greater than a first coefficient decrease threshold larger than the first coefficient change threshold. ,
The steering amount determination device according to claim 1 or 2. The second coefficient setting unit sets the second coefficient when the lateral speed is equal to or greater than the second coefficient change threshold and the lateral speed is equal to or greater than a second coefficient increase threshold which is larger than the second coefficient change threshold. increase the
The steering amount determination device according to any one of claims 1 to 3.

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