JP7392793B1 - Steering control device - Google Patents

Abstract

An object of the present invention is to improve the ability of a vehicle to follow a travel route. [Solution] A steering control device 1 calculates a lateral deviation, which is a distance in the width direction of the own vehicle 3 between a route point of a traveling route on which the own vehicle 3 travels, or a distance between the own vehicle 3 and the own vehicle 3, or the progress of the own vehicle 3 from the own vehicle 3. a deviation acquisition unit 123 that obtains a azimuth deviation that is the angle between a first straight line extending in the direction of the vehicle 3 and a second straight line that passes through the host vehicle 3 and the route point; a first yaw rate determining unit 124 that determines a first yaw rate of the host vehicle 3 by determining a value that minimizes a cost function with the yaw rate as a parameter; a lateral deviation or azimuth deviation; an integrated value of the lateral deviation or azimuth deviation; and a second yaw rate determination unit 125 that determines a value proportional to at least one of the amount of change in the lateral deviation or the azimuth deviation as the second yaw rate of the own vehicle 3, and a total yaw rate that is the sum of the first yaw rate and the second yaw rate. and a yaw rate control unit 126 that uses the steering angle to determine the commanded steering angle. [Selection diagram] Figure 3

Description

The present invention relates to a steering control device that controls the steering angle of a host vehicle.

Techniques for controlling steering so that vehicles travel along a target route are known. Patent Document 1 discloses a technique for steering a vehicle in accordance with a target amount of steering control necessary for the vehicle to travel on a target route.

Japanese Patent Application Publication No. 3-268110

However, due to the response delay between outputting a steering instruction and the actual change in the steering angle, changes in vehicle conditions, and disturbances received from the surrounding environment, it is difficult to input a control target amount that causes the vehicle to travel along the target route. However, the position of the vehicle may deviate from the driving route.

The present invention has been made in view of these points, and it is an object of the present invention to improve the ability of the own vehicle to follow a travel route.

In an aspect of the present invention, there is provided a lateral deviation that is a distance in the width direction of the own vehicle between the traveling route traveled by the own vehicle and the own vehicle, and a first straight line extending from the own vehicle in the direction in which the own vehicle travels. and an azimuth deviation that is an angle formed by the host vehicle and a second straight line passing through a position on the travel route; a first yaw rate determination unit that determines a first yaw rate of the host vehicle by determining a value that minimizes a cost function with the yaw rate as a parameter; a second yaw rate determination unit that determines a second yaw rate of the own vehicle to be a value proportional to at least one of the lateral deviation and the amount of change in the lateral deviation or the azimuth deviation; A steering control device is provided that includes a yaw rate control section that determines a commanded steering angle using a summed yaw rate.

The deviation acquisition unit is configured to calculate a position on a close approximation function that approximates a plurality of route points within a proximity range including the nearest route point closest to the current position of the host vehicle among the plurality of route points on the travel route; Obtaining the lateral deviation from the host vehicle or the azimuth deviation, which is the angle formed by the second straight line passing through the position on the proximity approximation function and the first straight line, and determining the second yaw rate. The section calculates a value proportional to at least one of the lateral deviation or the azimuth deviation of the closest route point, the integrated value of the lateral deviation or the azimuth deviation, and the amount of change in the lateral deviation or the azimuth deviation. 2 yaw rate may be determined.

The deviation acquisition unit is configured to calculate the lateral deviation in the width direction of the host vehicle from each of a plurality of route points in a forward range that does not include the nearest route point among the plurality of route points on the traveling route, and the forward The first yaw rate determination unit acquires the azimuth deviation, which is an angle between the second straight line and the first straight line passing through each route point within the range and the own vehicle, and The first yaw rate may be determined by finding a value that minimizes the cost function including a deviation and a potential according to the azimuth deviation.

The deviation acquisition unit indicates each route point within the forward range whose distance from the own vehicle is a predetermined value or more and which is greater than or equal to a minimum distance proportional to the speed of the own vehicle and less than or equal to a forward distance greater than the minimum distance. The method includes a loss term indicating the degree of discrepancy of a forward approximation function that approximates a data string in which coordinates are arranged in order of proximity to the own vehicle, and a gain term proportional to the forward distance, and minimizes a function using the forward distance as a parameter. A forward distance may also be determined.

A Kalman filter including a state equation representing a time transition of coefficients of the forward approximation function, and an observation equation that takes coordinates indicating each route point within the forward range as an observable quantity and describes a relationship between the observable quantity and the coefficient. The deviation acquisition unit further includes a coefficient updating unit that updates the coefficients using the updated coefficients, and the deviation acquisition unit calculates the lateral deviation and the azimuth deviation between the own vehicle and the position on the forward approximation function represented by the updated coefficients. and a curvature of the forward approximation function, and the first yaw rate determination unit minimizes the cost function including the potential generated using the lateral deviation, the azimuth deviation, and the curvature. 1 yaw rate may be determined.

a state equation representing a time transition of a coefficient of the close approximation function that approximates a data string in which coordinates indicating each route point within the close range are arranged in order of proximity from the host vehicle; and a state equation representing a time transition of a coefficient of the close approximation function, and the coordinates of each route point within the close range. is an observed quantity, and further includes a coefficient updating unit that updates the coefficient using a Kalman filter that includes an observation equation that describes a relationship between the observed quantity and the coefficient, and the deviation acquisition unit The position determined by inputting the coordinates of one of the plurality of route points within the proximity range or the coordinates of the origin into the proximity approximation function expressed by You may obtain it.

The second yaw rate determination unit is configured to calculate a product of the lateral deviation or the azimuth deviation and a proportional gain, a product of the integrated value of the lateral deviation or the azimuth deviation and an integral gain, and an amount of change in the lateral deviation or the azimuth deviation. The second yaw rate may be determined as the sum of products of and a differential gain.

The yaw rate control unit determines the commanded steering angle using the total yaw rate if the host vehicle is traveling along the travel route, and determines the commanded steering angle using the total yaw rate; For example, the commanded steering angle may be determined using only the first yaw rate.

According to the present invention, it is possible to improve the ability of the own vehicle to follow the travel route.

FIG. 3 is a diagram for explaining an overview of processing executed by the steering control device according to the embodiment. FIG. 3 is a diagram for explaining a front range. FIG. 2 is a diagram for explaining the configuration of a steering control device. 3 is a flowchart illustrating an example of a process for determining a commanded steering angle.

[Summary of processing executed by steering control device 1]
2. Description of the Related Art Conventionally, control is known in which a vehicle is steered according to an instruction steering angle necessary for the vehicle to travel on a travel route. However, due to a response delay between when a steering instruction is output and when the steering angle actually changes, and due to disturbances such as changes in the vehicle condition and surrounding conditions, the indicated steering angle necessary to travel on the driving route may be delayed. Even if you input the information, the position of your vehicle may deviate from the driving route.

Therefore, the steering control device according to the embodiment allows the vehicle to travel along the route points of the travel route and reduce the influence of disturbances by combining control for traveling along the travel route and control for reducing the influence of disturbances. Determine the commanded steering angle to reduce. An overview of the processing executed by the steering control device will be explained below. FIG. 1 is a diagram for explaining an overview of processing executed by a steering control device 1 according to an embodiment. The steering control device 1 is mounted on a self-driving vehicle, which is an automatic driving vehicle.

The first yaw rate determining unit 124 of the steering control device 1 determines a first yaw rate (hereinafter referred to as "forward yaw rate") for driving the vehicle along the travel route through control based on the driver model. When determining the forward yaw rate, if the vehicle is caused to travel along a route point close to the current position of the own vehicle, the change in the forward yaw rate becomes large because the vehicle attempts to approach a route point close to the current position. Therefore, the first yaw rate determination unit 124 determines the forward yaw rate using a forward approximation function that approximates a plurality of route points within the forward range that do not include the closest route point on the travel route. The forward approximation function is, for example, a quadratic function, a cubic function, or a spline curve, but is not limited thereto. In this embodiment, a case will be described in which the forward approximation function is a quadratic function.

FIG. 2 is a diagram for explaining the front range FR. In this embodiment, a coordinate system centered on the rear wheel axis of the own vehicle 3 is used, and the traveling direction X of the own vehicle 3 is indicated by the vertical axis, and the traveling direction X is positive from the bottom to the top of the page. . Further, the width direction Y of the host vehicle 3 is indicated by the horizontal axis, and the width direction Y is positive from right to left in the paper. The black circles in FIG. 2 are route points on the travel route of the own vehicle 3. The nearest route point NP is the route point closest to the current position of the host vehicle 3 among the plurality of route points on the travel route along which the host vehicle 3 travels.

The first yaw rate determining unit 124 includes a potential corresponding to a forward approximation function FF that approximates a plurality of route points within a forward range FR of a minimum distance L _min or more and a forward distance L or less, and a cost function that uses the forward yaw rate as a parameter. Determine the forward yaw rate to minimize. In this way, the first yaw rate determination unit 124 can reduce the change in the forward yaw rate by referring to the route points of the host vehicle 3 within the forward range FR.

Incidentally, by using route points within the forward range FR, changes in the forward yaw rate can be reduced; however, when influenced by disturbances, the proximity lateral deviation d2 between a route point close to the own vehicle 3 and the own vehicle 3 tends to increase. Therefore, the second yaw rate determining unit 125 of the steering control device 1 determines a second yaw rate (hereinafter referred to as "proximity yaw rate") for reducing the influence of disturbance based on PID (Proportional-Integral-Differential) control. . The second yaw rate determination unit 125 determines the proximity yaw rate based on the intersection point KP between the proximity approximation function KF and the width direction Y axis of the host vehicle 3 and the proximity lateral deviation d2, which is the distance from the host vehicle 3 in the width direction Y. .

The close approximation function KF is a function that approximates a plurality of route points within the proximal range PR including the closest route point NP. The close approximation function KF is, for example, a quadratic function, a cubic function, or a spline curve, but is not limited thereto. In this embodiment, a case will be described in which the close approximation function KF is a quadratic function. The upper limit of the proximity range PR is, for example, the minimum distance L _min , but is not limited to this, and may be a value obtained by adding a predetermined value to the length of the own vehicle 3. The predetermined value may be determined as appropriate. The second yaw rate determination unit 125 determines a value proportional to the proximity lateral deviation d2 as the proximity yaw rate. Since the second yaw rate determination unit 125 determines the proximity yaw rate that is proportional to the proximity lateral deviation d2, it is possible to reduce the proximity lateral deviation d2 caused by the disturbance. As a result, the second yaw rate determination unit 125 can reduce the influence of disturbances.

The yaw rate control unit 126 of the steering control device 1 determines the commanded steering angle using a total yaw rate that is the sum of the forward yaw rate and the proximity yaw rate. ECU (Electronic Control Unit) 2 is a control device that controls own vehicle 3, and controls the steering angle of own vehicle 3 according to an instruction steering angle. Thereby, the ECU 2 can reduce the influence of disturbances such as changes in the state of the own vehicle 3 and surrounding conditions while driving the own vehicle 3 along the route points, thereby improving the ability to follow the traveling route of the own vehicle 3. can.

[Configuration of steering control device 1]
FIG. 3 is a diagram for explaining the configuration of the steering control device 1. As shown in FIG. The host vehicle 3 is equipped with an ECU 2 and a sensor group 4 in addition to the steering control device 1 .

ECU 2 is a control device that controls own vehicle 3 . The ECU 2 controls the angle of the steered wheels (steering angle) of the own vehicle 3 so that the yaw rate determined by the steering control device 1 is achieved.

The sensor group 4 is a sensor that detects the state of the own vehicle 3. The sensor group 4 includes a GPS (Global Positioning System) receiver for detecting the position of the own vehicle 3 , and detects the position of the own vehicle 3 . Further, the sensor group 4 includes a sensor that detects the yaw rate as the state of the host vehicle 3, and detects the yaw rate.

The steering control 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 calculation resource including a processor such as a CPU (Central Processing Unit). The control unit 12 executes the program stored in the storage unit 11 to update the first coefficient update unit 121, the second coefficient update unit 122, the deviation acquisition unit 123, the first yaw rate determination unit 124, and the second yaw rate determination unit. 125 and a yaw rate control section 126.

The first coefficient updating unit 121 updates the coefficients of a forward approximation function FF that approximates a plurality of route points within the forward range FR. When updating the coefficients of the forward approximation function FF, the first coefficient updating unit 121 sets a minimum distance L _min which is the lower limit value of the forward range FR, and a front distance L which is the upper limit value larger than the minimum distance L _min . Determine. The first coefficient updating unit 121 determines a minimum distance L _min that is proportional to the speed V of the own vehicle 3 whose distance from the own vehicle 3 is a predetermined value or more. Specifically, the first coefficient updating unit 121 determines the minimum distance L _min using the following formula (1).

L _min =A+VΔτ…(1)
A is the distance from the front of the host vehicle 3 to the rear wheel axle. Δτ is the response delay time required from when the commanded steering angle is output to when the steering angle actually changes, and the specific value is 1 second, but it is not limited to this and can be changed as appropriate based on experiments etc. Just set it. Note that the first coefficient updating unit 121 sets the minimum distance L _min to a predetermined value when the minimum distance L _min exceeds a predetermined value. The predetermined value may be appropriately set, for example, in a range of 15 meters or more and 20 meters or less, but is not limited to this.

aは定数であり、実験などにより適宜定めればよい。式（２）の第１項は、前方近似関数ＦＦの不一致度を示す損失項である。式（２）の第２項は、aを係数とする前方距離Ｌに比例する利得項である。なお、第１係数更新部１２１は、自車両３から所定距離以内の走行経路の曲率又は自車両３が走行する道路の曲率が小さいほどaを大きくしてもよい。 The first coefficient updating unit 121 includes a loss term indicating the degree of inconsistency of the forward approximation function FF and a gain term proportional to the forward distance L, and calculates a value that minimizes the function using the forward distance L as a parameter. Determine. Specifically, the first coefficient updating unit 121 determines the forward distance L using the following equation (2).

a is a constant, and may be determined as appropriate through experiments or the like. The first term in equation (2) is a loss term indicating the degree of mismatch of the forward approximation function FF. The second term in equation (2) is a gain term proportional to the forward distance L with a as a coefficient. Note that the first coefficient updating unit 121 may increase a as the curvature of the travel route within a predetermined distance from the host vehicle 3 or the curvature of the road on which the host vehicle 3 travels is smaller.

The first coefficient update unit 121 substitutes the values from the minimum distance L _min to the upper limit L _max of the forward distance L into equation (2), and determines the value that minimizes equation (2) as the forward distance L. . The upper limit L _max may be determined as appropriate, and a specific value is 100 meters, but it may also be 150 meters, and is not limited to these. Thereby, the first coefficient updating unit 121 can increase the forward distance L as much as possible while reducing the degree of mismatch of the forward approximation function FF. The first coefficient updating unit 121 determines a range from the minimum distance L _min to the determined forward distance L as the forward range FR.

The first coefficient updating unit 121 updates the coefficients of the forward approximation function FF that approximates a data string in which coordinates indicating each route point within the forward range FR are arranged in order of distance from the host vehicle. For example, the first coefficient updating unit 121 uses a state equation representing the time transition of the coefficients of the forward approximation function FF and coordinates indicating each route point within the forward range FR as observable quantities, and describes the relationship between the observable quantities and the coefficients. The coefficients of the forward approximation function FF are updated using a Kalman filter including the forward observation equation. The state equation is expressed by the following equation (3), and the forward observation equation is expressed by the following equation (4).

In equations (3) and (4), the noise term is omitted. N in equation (4) is the number of route points included in the forward range FR. Note that when the forward distance L of the forward range FR changes, the number of route points included in the forward range also changes. Therefore, N is the number of route points included in the forward range FR when the forward distance L is the upper limit value L _max . Note that if the number of route points included in the forward range FR is smaller than N, X _i after the number of route points is set to 0. To give a specific example, if N is 400 and the number of route points included in the forward range FR is 300, the first coefficient updating unit 121 updates the 300th X from _{the 300th} to the 400th X Set X _i up to ₄₀₀ to 0.

The deviation acquisition unit 123 acquires a forward lateral deviation d1 that is a lateral deviation between the position within the forward range FR on the forward approximation function FF represented by the updated coefficient and the own vehicle 3. For example, the deviation acquisition unit 123 acquires the front lateral deviation d1, which is the distance between the position within the forward range FR on the forward approximation function and the position on the traveling direction X-axis. In addition, the deviation acquisition unit 123 acquires the azimuth deviation, which is the angle between the first straight line extending from the own vehicle 3 in the direction in which the own vehicle 3 is traveling, and the second straight line passing through the own vehicle 3 and the position on the travel route. do. Specifically, the deviation acquisition unit 123 acquires the azimuth deviation, which is the angle formed by the own vehicle 3 and a second straight line passing through the position on the forward approximation function FF. The deviation acquisition unit 123 may acquire the curvature of the forward approximation function FF. For example, the deviation acquisition unit 123 divides the forward approximation function FF into a plurality of sections and acquires the curvature of each section.

The first yaw rate determination unit 124 determines the forward yaw rate of the own vehicle 3 by finding a value that minimizes a cost function that includes a potential according to the forward approximation function FF and uses the forward yaw rate of the own vehicle 3 as a parameter. The potential corresponding to the forward approximation function FF is a lane potential generated using the forward lateral deviation d1, the azimuth deviation, and the curvature of the forward approximation function FF, with the position on the forward approximation function FF as a reference. The lane potential has a minimum value at the position indicated by the front lateral deviation d1 and the azimuth deviation, and is an attractive potential that is proportional to the front lateral deviation d1. The lane potential may be generated by the first yaw rate determination unit 124 or may be generated by another device mounted on the host vehicle 3.

The first yaw rate determination unit 124 determines the forward yaw rate by finding a value that minimizes a cost function that includes at least a lane potential and an obstacle potential according to obstacles existing around the host vehicle 3 and uses the forward yaw rate as a parameter. . The obstacle potential is a repulsive force potential that indicates the risk of contact between the own vehicle 3 and an obstacle. Specifically, the first yaw rate determining unit 124 determines a forward yaw rate that minimizes a cost function including contact risk according to lane potential and obstacle potential.

The second coefficient updating unit 122 updates the coefficients of the approximate approximation function KF that approximates each route point within the proximity range PR. For example, the second coefficient updating unit 122 updates the coefficients of a near approximation function KF that approximates a data string in which coordinates indicating each route point within the proximity range PR are arranged in order of proximity from the own vehicle 3. Specifically, the second coefficient updating unit 122 uses a state equation representing the time transition of the coefficients of the approximate approximation function KF and the coordinates of each route point within the proximity range PR as observable quantities, and calculates the relationship between the observable quantities and the coefficients. The coefficients of the approximate approximation function KF are updated using a Kalman filter that includes a proximity observation equation that describes . The state equation is expressed by the above equation (3), and the proximity observation equation is expressed by the following equation (5).

In equation (5), the noise term is omitted. Note that the state equation used to update the coefficients of the near approximation function KF is expressed by the same equation as the state equation used to update the coefficients of the forward approximation function FF. The second coefficient updating unit 122 uses a state equation for updating the coefficients of the FF, and the second coefficient updating unit 122 uses a state equation for updating the coefficients of the close approximation function KF.

The deviation acquisition unit 123 acquires the proximity lateral deviation d2 between the position on the approximate approximation function KF expressed by the updated coefficient and the own vehicle 3. For example, the deviation acquisition unit 123 acquires the distance between the host vehicle 3 and the position determined by inputting the X coordinate (0) of the origin into the proximity approximation function KF as the proximity lateral deviation d2. The position determined by inputting the X coordinate (0) of the origin into the close approximation function KF is the intersection KP between the close approximation function KF and the width direction Y axis (see FIG. 2). In addition, the deviation acquisition unit 123 replaces the X coordinate (0) of the origin with a position determined by inputting the X coordinate of any one of the plurality of route points within the proximity range PR into the approximate approximation function KF. The distance from the host vehicle 3 in the width direction Y may be acquired as the proximity lateral deviation d2.

The second yaw rate determination unit 125 determines a proximity yaw rate that reduces the proximity lateral deviation d2 acquired by the deviation acquisition unit 123 based on PID control. For example, the second yaw rate determination unit 125 determines a value proportional to at least one of the proximity lateral deviation d2, the integrated value of the proximity lateral deviation d2, and the amount of change in the proximity lateral deviation d2 as the proximity yaw rate of the host vehicle 3. . Specifically, the second yaw rate determination unit 125 calculates the product of the proximity lateral deviation d2 and the proportional gain, the product of the integrated value of the proximity lateral deviation d2 and the integral gain, and the product of the amount of change in the proximity lateral deviation d2 and the differential gain. The sum of the products of is determined to be the proximate yaw rate.

The yaw rate control unit 126 determines the commanded steering angle using a total yaw rate that is the sum of the forward yaw rate and the proximity yaw rate. For example, if the host vehicle 3 is traveling along the travel route, the yaw rate control unit 126 determines the commanded steering angle using the total yaw rate. The yaw rate control unit 126 determines the commanded steering angle using only the forward yaw rate if the host vehicle 3 is not traveling along the travel route. The yaw rate control unit 126 inputs the determined command steering angle to the ECU 2. The ECU 2 controls the angle of the steered wheels (steering angle) of the own vehicle 3 so that the steering angle becomes the commanded steering angle.

[Process for determining the commanded steering angle]
FIG. 4 is a flowchart illustrating an example of a process for determining a commanded steering angle. The flowchart in FIG. 4 is executed at predetermined intervals while the own vehicle 3 is traveling. The predetermined interval is, for example, 50 milliseconds, but is not limited to this.

[Processing to determine the commanded steering angle]
The first coefficient update unit 121 determines the forward distance L (step S1). For example, the first coefficient updating unit 121 determines, as the front distance L, a value that minimizes equation (2) among the values from the minimum distance L _min to the upper limit L _max of the front distance L.

The first coefficient updating unit 121 updates the first coefficient of the forward approximation function FF that approximates each route point within the forward range FR that is greater than or equal to the minimum distance L _min and less than or equal to the forward distance L (step S2). For example, the first coefficient updating unit 121 uses the state equation (formula (3)) representing the time transition of the first coefficient of the forward approximation function FF and the coordinates indicating each route point within the forward range FR as observable quantities, and uses the observed The first coefficient of the forward approximation function FF is updated using a Kalman filter that includes a forward observation equation (formula (4)) that describes the relationship between quantities and coefficients.

The deviation acquisition unit 123 acquires the front lateral deviation d1, which is the distance in the width direction Y between the position on the forward approximation function FF and the host vehicle 3 (step S3). Specifically, the deviation acquisition unit 123 obtains the forward lateral deviation d1 and azimuth deviation between each position within the forward range FR on the forward approximation function FF whose coefficients have been updated and the own vehicle 3, and the curvature of the forward approximation function FF. and get.

The first yaw rate determining unit 124 determines the forward yaw rate (step S4). For example, the first yaw rate determination unit 124 determines the forward yaw rate of the own vehicle 3 by determining a value that minimizes a cost function that includes the lane potential according to the forward approximation function FF and uses the forward yaw rate of the own vehicle 3 as a parameter. do. Specifically, the first yaw rate determination unit 124 determines a forward yaw rate that minimizes a cost function that includes the forward lateral deviation d1, the azimuth deviation, and the lane potential generated using the curvature of the forward approximation function FF.

The second coefficient updating unit 122 determines whether the driving mode of the host vehicle 3 is a route following mode in which the vehicle 3 travels along the driving route (step S5). If the driving mode of the host vehicle 3 is the route following mode (Yes in step S5), the second coefficient updating unit 122 updates the second coefficient of the close approximation function KF that approximates each route point within the proximity range PR. (Step S6). Specifically, the second coefficient updating unit 122 uses the state equation (formula (3)) representing the time transition of the coefficient of the approximate approximation function KF and the coordinates of each route point within the proximity range PR as observable quantities, and calculates the observed value. The coefficients of the close approximation function KF are updated using a Kalman filter that includes a close observation equation (formula (5)) that describes the relationship between quantities and coefficients.

After updating the coefficients of the close approximation function KF, the deviation acquisition unit 123 acquires the close lateral deviation d2 corresponding to the route point within the forward range FR (step S7). For example, the deviation acquisition unit 123 generates a proximity lateral deviation d2 between the host vehicle 3 and the intersection KP (see FIG. 2), which is a position determined by inputting the X coordinate (0) of the origin into the approximate approximation function KF with updated coefficients. get.

The second yaw rate determination unit 125 determines the proximity yaw rate using the proximity lateral deviation d2 (step S8). Specifically, the second yaw rate determination unit 125 calculates the product of the proximity lateral deviation d2 and the proportional gain, the product of the integrated value of the proximity lateral deviation d2 and the integral gain, and the product of the amount of change in the proximity lateral deviation d2 and the differential gain. The sum of the products of is determined to be the proximate yaw rate.

The yaw rate control unit 126 adds up the forward yaw rate and the proximity yaw rate to calculate a total yaw rate (step S9). Then, the yaw rate control unit 126 determines the commanded steering angle using the total yaw rate (step S10). If the driving mode of the host vehicle 3 is not the route following mode (No in step S5), the yaw rate control unit 126 determines the commanded steering angle only based on the forward yaw rate (step S11).

(Modified example)
In the embodiment described above, the second yaw rate is determined using the lateral deviation. However, the steering control device 1 may determine the second yaw rate using the azimuth deviation. When using the azimuth deviation, the deviation acquisition unit 123 may determine the second yaw rate using the azimuth deviation. Obtain the azimuth deviation, which is the angle formed with the first straight line. The second yaw rate determination unit 125 calculates the product of the nearest route point NP, the azimuth deviation of the host vehicle 3, and the proportional gain, the product of the integrated value of the azimuth deviation and the integral gain, and the product of the amount of change in the azimuth deviation and the differential gain. The sum of the products of is determined to be the proximate yaw rate.

[Effects of steering control device 1]
As explained above, the steering control device 1 determines the forward yaw rate that minimizes the cost function that includes the potential according to the traveling route of the own vehicle 3 and uses the forward yaw rate of the own vehicle 3 as a parameter, and also , the integrated value of the lateral deviation, and the amount of change in the lateral deviation. Then, the steering control device 1 determines the commanded steering angle using a total yaw rate that is the sum of the forward yaw rate and the proximity yaw rate.

Since the cost function becomes smaller when the host vehicle 3 travels at the center of the potential, the steering control device 1 determines a larger forward yaw rate as the lateral deviation between the travel route and the host vehicle in the width direction increases. Further, the steering control device 1 can reduce the lateral deviation caused by disturbance by using the proximity yaw rate. Then, by adding up the forward yaw rate and the proximity yaw rate, the steering control device 1 can determine a commanded steering angle that allows the vehicle to travel along the route points of the travel route and reduce the influence of disturbances. As a result, the deviation of the position of the own vehicle 3 from the traveling route can be reduced, and the ability of the own vehicle to follow the traveling route can be improved.

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 can be made within the scope of the gist. be. For example, all or part of the device can be functionally or physically distributed and integrated into arbitrary units. In addition, new embodiments created by arbitrary combinations of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiment resulting from the combination have the effects of the original embodiment.

1 Steering control device 11 Storage unit 12 Control unit 121 First coefficient update unit 122 Second coefficient update unit 123 Deviation acquisition unit 124 First yaw rate determination unit 125 Second yaw rate determination unit 126 Yaw rate control unit 2 ECU
3 Own vehicle 4 Sensor group

Claims (3)

a lateral deviation that is the distance between the own vehicle and the traveling route traveled by the own vehicle in the width direction of the own vehicle; a first straight line extending from the own vehicle in the direction in which the own vehicle travels; the own vehicle and the traveling direction; a deviation acquisition unit that acquires at least one of an azimuth deviation that is an angle formed with a second straight line passing through a position on the route;
a first yaw rate determination unit that determines a first yaw rate of the host vehicle by determining a value that minimizes a cost function that includes a potential according to the travel route and uses the yaw rate of the host vehicle as a parameter;
A value proportional to at least one of the lateral deviation or the azimuth deviation, the integrated value of the lateral deviation or the azimuth deviation, and the amount of change in the lateral deviation or the azimuth deviation is determined as a second yaw rate of the host vehicle. a second yaw rate determining section;
a yaw rate control unit that determines a commanded steering angle using a total yaw rate that is a sum of the first yaw rate and the second yaw rate;
has
The deviation acquisition unit is configured to calculate a position on a close approximation function that approximates a plurality of route points within a proximity range including the nearest route point closest to the current position of the host vehicle among the plurality of route points on the travel route; Obtaining the lateral deviation with respect to the host vehicle, or the azimuth deviation that is the angle formed by the second straight line passing through the position on the near approximation function and the host vehicle and the first straight line,
The second yaw rate determination unit is proportional to at least one of the lateral deviation or the azimuth deviation, the integrated value of the lateral deviation or the azimuth deviation, and the amount of change in the lateral deviation or the azimuth deviation of the nearest route point. determining a value for the second yaw rate;
The deviation acquisition unit is configured to calculate the lateral deviation in the width direction of the host vehicle from each of a plurality of route points in a forward range that does not include the nearest route point among the plurality of route points on the traveling route, and the forward obtaining the azimuth deviation, which is the angle formed by the second straight line passing through each route point within the range and the own vehicle, and the first straight line;
The first yaw rate determination unit determines the first yaw rate by determining a value that minimizes the cost function including a potential according to the lateral deviation and the azimuth deviation within the forward range,
The deviation acquisition unit indicates each route point within the forward range whose distance from the own vehicle is a predetermined value or more and which is greater than or equal to a minimum distance proportional to the speed of the own vehicle and less than or equal to a forward distance greater than the minimum distance. The method includes a loss term indicating the degree of discrepancy of a forward approximation function that approximates a data string in which coordinates are arranged in order of proximity to the own vehicle, and a gain term proportional to the forward distance, and minimizes a function using the forward distance as a parameter. A steering control device that determines the forward distance . a state equation representing a time transition of a coefficient of the close approximation function that approximates a data string in which coordinates indicating each route point within the close range are arranged in order of proximity from the host vehicle; and a state equation representing a time transition of a coefficient of the close approximation function, and the coordinates of each route point within the close range. is an observed quantity, and further includes a coefficient updating unit that updates the coefficient using a Kalman filter including an observation equation that describes a relationship between the observed quantity and the coefficient,
The deviation acquisition unit calculates a position obtained by inputting the coordinates of one of the plurality of route points within the proximity range or the coordinates of the origin into the approximate approximation function represented by the updated coefficient; obtaining the lateral deviation or the azimuth deviation with respect to the vehicle;
The steering control device according to claim 1 . The second yaw rate determination unit is configured to calculate a first product of the lateral deviation or the azimuth deviation and a proportional gain , a second product of the integrated value of the lateral deviation or the azimuth deviation and an integral gain , and the lateral deviation or the proportional gain. determining the sum of a third product of the amount of change in the azimuth deviation and the differential gain as the second yaw rate;
The steering control device according to claim 2 .

Images