Vehicle steering systems

Abstract

The present invention is a vehicle steering system capable of reducing the burden on the driver. The system comprises: a steering control amount calculation unit (11) for calculating a steering control amount for causing the vehicle to follow a target travel line; a lateral deviation change prediction amount calculation unit (12) for calculating a lateral deviation change prediction amount obtained by predicting a lateral deviation change amount of the vehicle relative to the target travel line; and a steering control amount limiting unit (13) for calculating a steering control amount limit value based on a steering force and a lateral deviation change prediction amount, and outputting a limited steering control amount obtained by limiting the steering control amount by the steering control amount limit value. When the absolute value of the steering force is the same, the steering control amount limiting unit (13) sets the steering control amount limit value to a larger value or the same value as when the absolute value of the lateral deviation change prediction amount is smaller.

Description

Technical Field

[0001] The present application relates to a steering system for a vehicle. Background Art

[0002] In a vehicle steering system that provides steering assistance to ensure the vehicle follows a desired target travel line, a technology has been proposed to reduce the driver's stress by minimizing the interference between the driver's steering and the assisted steering. For example, only when the vehicle's travel position exceeds a threshold line set further outward from the target travel line in the lane width direction, the steering control amount in the direction of the steering reaction force acting on the driver's steering is increased to draw the driver's attention without causing any annoyance (see, for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-182303 Summary of the Invention

[0006] Technical problem to be solved by the invention

[0007] In conventional vehicle steering systems, the steering control amount is increased based on the deviation between the vehicle's driving position and the target driving line in the lane width direction. Therefore, for example, when the driver wishes to drive on the inside of a curve on a curved road, when the driver steers in order to maintain the driving line in the lane outside the threshold line, the steering control amount in the direction of following the target driving line increases, thereby placing a burden on the driver.

[0008] The present application has been made to solve the above-mentioned problems, and an object thereof is to provide a vehicle steering system that reduces the burden on the driver.

[0009] Technical means for solving technical problems

[0010] The vehicle steering system disclosed in the present application includes: a steering input unit for a driver to perform steering operations; a steering force detection unit for detecting a steering force input to the steering input unit; a steering control quantity calculation unit for calculating a steering control quantity for causing the vehicle to follow a target driving line; a lateral deviation change prediction quantity calculation unit for calculating a lateral deviation change prediction quantity, wherein the lateral deviation change prediction quantity is obtained by predicting the lateral deviation change quantity of the vehicle relative to the target driving line; a steering control quantity limiting unit for calculating a steering control quantity limit value based on the steering force and the lateral deviation change prediction quantity, and outputting a limited steering control quantity obtained by limiting the steering control quantity by the steering control quantity limit value; and a steering control unit for controlling the steering of the vehicle based on the limited steering control quantity, wherein, under the condition that the absolute value of the steering force is the same, when the absolute value of the lateral deviation change prediction quantity is larger, the steering control quantity limiting unit sets the steering control quantity limit value to a larger value or the same value as when the absolute value of the lateral deviation change prediction quantity is smaller.

[0011] Effects of the Invention

[0012] The vehicle steering system disclosed in the present application includes: a steering control quantity calculation unit that calculates a steering control quantity for causing the vehicle to follow a target driving line; a lateral deviation change prediction quantity calculation unit that calculates a lateral deviation change prediction quantity, the lateral deviation change prediction quantity being obtained by predicting the lateral deviation change quantity of the vehicle relative to the target driving line; and a steering control quantity limiting unit that calculates a steering control quantity limit value based on the steering force and the lateral deviation change prediction quantity, and outputs a limited steering control quantity obtained by limiting the steering control quantity by the steering control quantity limit value. Under the condition that the absolute value of the steering force is the same, when the absolute value of the lateral deviation change prediction quantity is larger, the steering control quantity limiting unit sets the steering control quantity limit value to a larger value or the same value as when the absolute value of the lateral deviation change prediction quantity is smaller. Therefore, when it is predicted that the driver intentionally drives on a line different from the target driving line without moving away from the target driving line, the burden on the driver can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a block diagram showing the configuration of a vehicle steering system according to the first embodiment.

[0014] Figure 2 This is a diagram showing the yaw angle in the vehicle steering system according to the first embodiment.

[0015] Figure 3 This is a flowchart illustrating the operation of the steering control amount limiting unit in the vehicle steering system according to the first embodiment.

[0016] Figure 4This is a diagram showing the relationship between the absolute value of the steering force, the lateral deviation variation prediction amount, and the steering control amount correction coefficient in the vehicle steering system according to the first embodiment.

[0017] Figure 5 This is a diagram showing the relationship between the absolute value of the steering force, the lateral deviation variation prediction amount, and the steering control amount correction coefficient in the vehicle steering system according to the second embodiment.

[0018] Figure 6 This is a block diagram showing the configuration of a vehicle steering system according to a third embodiment.

[0019] Figure 7 This is a block diagram showing the configuration of a vehicle steering system according to a fourth embodiment.

[0020] Figure 8 This is a block diagram showing the configuration of a vehicle steering system according to the fifth embodiment.

[0021] Figure 9 This is a diagram showing the hardware configuration of a steering device in a vehicle steering system according to the first to fifth embodiments. DETAILED DESCRIPTION

[0022] Hereinafter, a vehicle steering system according to an embodiment of the present application will be described in detail with reference to the accompanying drawings.

[0023] Implementation method 1.

[0024] Figure 1 This is a block diagram showing the structure of a vehicle steering system according to Embodiment 1. The vehicle steering system according to Embodiment 1 includes a steering device 1, a steering input unit 2, a steering force detection unit 3, a driving path recognition unit 4, a vehicle speed detection unit 5, and a steering actuator 6. In this specification, "vehicle" refers to a vehicle equipped with the steering device 1. The steering device 1 includes a target driving line setting unit 10, a steering control amount calculation unit 11, a lateral deviation change prediction amount calculation unit 12, a steering control amount limiting unit 13, and a steering control unit 14. The steering force detected by the steering force detection unit 3 is input to the steering control amount limiting unit 13, the driving path information detected by the driving path recognition unit 4 is input to the target driving line setting unit 10, the vehicle speed detected by the vehicle speed detection unit 5 is input to the lateral deviation change prediction amount calculation unit 12, and the output from the steering control unit 14 is input to the steering actuator 6. In addition, the steering device 1 can have the control function of a general electric power steering device.

[0025] The steering input unit 2 is, for example, a steering wheel operated by the driver. Alternatively, the steering input unit 2 may be any input unit, such as a joystick or switch, as long as it is a unit operated by the driver to steer the vehicle. The steering force detector 3 is, for example, a torque sensor connected to the steering input unit 2. It detects the steering force input by the driver to the steering input unit 2 and outputs it to the steering device 1.

[0026] The driving path recognition unit 4 recognizes lane boundary lines such as the outer lane line, lane boundary line, and lane center line of the front driving path based on the image in front of the vehicle captured by a camera or the like. Then, the driving path of the vehicle is recognized based on the position of the lane boundary lines in the vehicle coordinate system, and the driving path information is output to the steering device 1 as driving path information. The vehicle coordinate system is a coordinate system centered on a base point set at the vehicle. In addition, although the driving path recognition unit 4 generates driving path information based on the image captured by the camera, any method can be used as long as it is a method that can generate driving path information. For example, the vehicle's position information can be obtained from an artificial satellite, and the driving path information can be generated based on map information and the acquired position information. Alternatively, the driving path information can be generated based on the driving trajectory of the vehicle traveling in front captured by a radar or camera or the like.

[0027] The vehicle speed detection unit 5 detects the vehicle speed and outputs it to the steering system 1. The steering actuator 6 generates steering power based on the output from the steering control unit 14 to steer the vehicle. The steering actuator 6 is, for example, an electric power steering motor or a hydraulic motor. The type of motor is not particularly limited and can be a DC motor or an AC motor.

[0028] Next, the structure of the steering device 1 will be described. The target driving line setting unit 10 sets the target driving line as the driving path based on the driving path information in the vehicle coordinate system obtained from the driving path recognition unit 4. The target driving line becomes the target for causing the vehicle to follow the driving path, and the target driving line setting unit 10 outputs the target driving line information to the steering control amount calculation unit 11 and the lateral deviation change prediction amount calculation unit 12. The target driving line is set, for example, at a position separated by a predetermined distance from the right boundary line of the lane in the vehicle coordinate system. If the target driving line is set at a position separated by 1 / 2 of the width of the driving path from the right boundary line of the lane, the target driving line is set in the center of the driving path. In addition, the position of the target driving line in the driving path can be changed according to the driver's preference or the surrounding environment.

[0029] The steering control amount calculation unit 11 calculates a steering control amount for causing the vehicle to follow the target travel line based on the target travel line information received from the target travel line setting unit 10, and outputs the calculated steering control amount to the steering control amount limiting unit 13. The method for calculating the steering control amount in the steering control amount calculation unit 11 may be any method as long as the method for calculating the steering control amount for following the target travel line is such as the method described in Japanese Patent No. 6012824, which uses the target torque for driving the steering actuator as the steering control amount.

[0030] The lateral deviation variation predicted amount calculation unit 12 first determines a yaw angle, which is an angle formed between the vehicle's traveling direction and the target traveling line, based on the target traveling line acquired from the target traveling line setting unit 10 . Figure 2 : is a diagram showing the yaw angle in the vehicle steering system according to the first embodiment. Figure 2 The angle between the traveling direction 21 of the vehicle 20 and the target traveling line 22 is the yaw angle C1. The lateral deviation change prediction amount calculation unit 12 then calculates the vehicle speed V obtained from the vehicle speed detection unit 5 based on the obtained yaw angle C1. x The lateral velocity V, which is the speed of the vehicle in the lane width direction, is calculated by the following formula: y and outputs it as the lateral deviation change prediction amount to the steering control amount limiting unit 13. The lateral speed V y The larger the value, the greater the change in the lateral deviation of the vehicle. Therefore, the lateral speed V y To predict the lateral deviation change. Here, although the yaw angle is Figure 2 In the figure, it is set as the angle between the vehicle's traveling direction and the target traveling line, but it can also be set as the angle between the vehicle's lateral target traveling line at a specified distance in front of the vehicle and the vehicle's traveling direction. In any case, geometric calculations can be easily performed based on the target traveling line in the vehicle coordinate system.

[0031] V y =V x tanC1 (1)

[0032] Alternatively, the lateral deviation, which is the deviation between the vehicle's driving position and the target driving line in the lane width direction, can be determined, and the predicted lateral deviation change amount calculated based on the change in the lateral deviation. In this case, for example, the lateral deviation can be sampled at a predetermined period, and the time change in the lateral deviation can be used as the predicted lateral deviation change amount.

[0033] Alternatively, the yaw angle itself can be used as a lateral deviation variation prediction amount. As the yaw angle increases, the lateral deviation variation of the vehicle increases, and thus the lateral deviation variation can be predicted using the yaw angle.

[0034] The steering control amount limiting unit 13 first calculates a steering control amount limiting value for reducing the steering control amount during the driver's steering operation, i.e., during override control, based on the steering force obtained from the steering force detection unit 3 and the predicted lateral deviation variation obtained from the predicted lateral deviation variation calculation unit 12. Next, the steering control amount limiting unit 13 calculates a limited steering control amount for limiting the steering control amount obtained from the steering control amount calculation unit 11 using the steering control amount limiting value, and outputs the limited steering control amount to the steering control unit 14.

[0035] Next, the operation of the steering control amount limiting unit 13 will be described in detail. Figure 3 This is a flowchart for explaining the operation of the steering control amount limiting unit 13. In step S101, the steering control amount limiting unit 13 reads the steering force output by the steering force detection unit 3, the steering control amount output by the steering control amount calculation unit 11, and the lateral deviation change prediction amount output by the lateral deviation change prediction amount calculation unit 12 as input values.

[0036] In step S102, a steering control amount correction coefficient α is calculated based on the steering force and lateral deviation change prediction read as input values ​​in step S101. The steering control amount correction coefficient α is a coefficient ranging from 0 to 1, for example. α = 1 indicates a state where the steering control amount for lane keeping is 100%, indicating that the vehicle's steering system assists the steering operation and follows the target travel line. Alternatively, α = 0 indicates a state where the steering control amount for lane keeping is 0%, indicating that the vehicle is manually steering. Therefore, when 0 < α < 1, the steering control amount for lane keeping is α × 100%, representing an intermediate state between a state where the vehicle's steering system assists the steering operation and follows the target travel line and a state where the vehicle is manually steering. In this state, the driver is steering, but the steering control of the vehicle's steering system is intervening in the driver's steering operation.

[0037] Next, a method of obtaining the steering control amount correction coefficient α from the steering force and the lateral deviation variation predicted amount will be described. Figure 4 This is a diagram showing the relationship between the absolute value of the steering force, the lateral deviation variation prediction amount, and the steering control amount correction coefficient, and shows a map when the steering control amount correction coefficient α is obtained from the absolute value of the steering force as a curve. Figure 4The figure shows three lines: a line representing the "mapping when the absolute value of the lateral deviation variation predicted amount is zero," a line representing the "mapping when the absolute value of the lateral deviation variation predicted amount is 0.25," and a line representing the "mapping when the absolute value of the lateral deviation variation predicted amount is 0.5 or greater." This shows that, in each map when the absolute value of the lateral deviation variation predicted amount is constant, when the absolute value of the steering force is zero, the steering control amount correction coefficient α remains unchanged or decreases, ultimately reaching α = 0, while increasing the absolute value of the steering force. Furthermore, when the absolute value of the steering force remains the same, the steering control amount correction coefficient α is set to a larger value or the same value when the absolute value of the lateral deviation variation predicted amount is larger than when the absolute value of the lateral deviation variation predicted amount is smaller.

[0038] When the absolute value of the predicted lateral deviation fluctuation is midway between the values ​​of the pre-set mappings, the steering control amount correction coefficient α is calculated by linearly interpolating the values ​​of the two pre-set mappings. For example, when the absolute value of the predicted lateral deviation fluctuation is 0.1, the steering control amount correction coefficient α is calculated by linearly interpolating the values ​​of the pre-set "mapping for when the absolute value of the predicted lateral deviation fluctuation is zero" and "mapping for when the absolute value of the predicted lateral deviation fluctuation is 0.25." This ensures that the steering control amount correction coefficient α changes continuously even when the predicted lateral deviation fluctuation changes, preventing discontinuous changes in the steering control amount.

[0039] In addition, Figure 4 In the illustrated map, the characteristic is represented by a broken line, but the shape of the characteristic may be any shape as long as the value of the steering control amount correction coefficient α remains the same or decreases as the absolute value of the steering force increases.

[0040] Although the steering control amount correction coefficient α is obtained by mapping, it can also be processed using a table. Therefore, by using a map or a table to obtain the steering control amount correction coefficient α, the steering control amount correction coefficient α can be easily obtained. In addition, if, when the absolute value of the lateral deviation change prediction amount remains the same, α = 1 when the absolute value of the steering force is zero, and the steering control amount correction coefficient α does not change or decreases as the absolute value of the steering force increases, ultimately becoming α = 0, and, when the absolute value of the steering force remains the same, when the absolute value of the lateral deviation change prediction amount is large, the value of the steering control amount correction coefficient α remains the same or increases compared to when the absolute value of the lateral deviation change prediction amount is small, then the steering control amount correction coefficient α can be obtained by any method. For example, instead of using a map or a table, the increase or decrease in the steering control amount correction coefficient can be obtained based on the steering force and the lateral deviation change prediction amount.

[0041] In step S103, the steering control amount limit value is determined by multiplying the steering control amount correction coefficient α calculated in step S102 by the absolute value of the steering control amount obtained from the steering control amount calculation unit 11 in step S101. Given the same absolute value of the steering force, when the absolute value of the predicted lateral deviation variation is larger, the steering control amount correction coefficient α is set to a larger value or the same value as when the absolute value of the predicted lateral deviation variation is smaller. Therefore, when the absolute value of the predicted lateral deviation variation is larger, the steering control amount limit value becomes larger or the same value as when the absolute value of the predicted lateral deviation variation is smaller. Alternatively, the steering control amount limit value can be determined by multiplying the steering control amount correction coefficient α by a predetermined set value. In this case, the set value serves as the upper limit value of the steering control amount for lane keeping steering assistance.

[0042] Although the steering control amount correction coefficient α is calculated in step S102 and the steering control amount limit value is calculated in step S103, any calculation method may be used if, under the same absolute value of the steering force, when the absolute value of the lateral deviation change predicted amount is larger, the steering control amount limit value becomes a larger value or the same value as when the absolute value of the lateral deviation change predicted amount is smaller.

[0043] In step S104, a limited steering control amount is obtained by limiting the steering control amount obtained from the steering control amount calculation unit 11 in step S101 so that its absolute value becomes equal to or less than the steering control amount limit value obtained in step S103. In step S105, the limited steering control amount obtained in step S104 is output to the steering control unit 14.

[0044] The steering control unit 14 controls the steering of the vehicle by causing the steering actuator 6 to generate steering power based on the limited steering control amount acquired from the steering control amount limiting unit 13 .

[0045] Thus, the vehicle steering system involved in the first embodiment includes: a steering input unit 2 for the driver to perform steering operations; a steering force detection unit 3 for detecting the steering force input to the steering input unit 2; a steering control amount calculation unit 11 for calculating a steering control amount for causing the vehicle to follow a target driving line; a lateral deviation change prediction amount calculation unit 12 for calculating a lateral deviation change prediction amount, the lateral deviation change prediction amount being obtained by predicting the lateral deviation change amount of the vehicle relative to the target driving line; a steering control amount limiting unit 13 for calculating a steering control amount limit value based on the steering force and the lateral deviation change prediction amount, and outputting a limited steering control amount obtained by limiting the steering control amount by the steering control amount limit value; and The steering control unit 14 controls the vehicle steering based on the limited steering control amount. When the absolute value of the predicted lateral deviation variation is large, the steering control amount limiting unit 13 sets the steering control amount limit value to a larger value or the same value as when the absolute value of the predicted lateral deviation variation is small, provided the absolute value of the steering force remains the same. Therefore, in the case of driver override, when the predicted lateral deviation variation relative to the target travel line is predicted to be large and the vehicle is moving laterally within the lane in a direction in which the distance from the target travel line is changing, the steering control amount limit value is set to a larger value or the same value, effectively notifying the driver of the changing distance from the target travel line. Furthermore, when the predicted lateral deviation variation relative to the target travel line is predicted to be small and the driver is intentionally traveling on a line different from the target travel line without departing from the target travel line, the steering control amount limit value is reduced, thereby reducing the steering control amount and any sense of discomfort on the driver.

[0046] Implementation method 2.

[0047] The structure and configuration of the vehicle steering system according to the second embodiment Figure 1 The structure of the vehicle steering system according to the embodiment 1 shown is the same, but Figure 3 The operation of step S102 in the flowchart showing the operation of the steering control amount limiting unit 13 is different. Figure 5 It is a diagram showing the relationship between the absolute value of the steering force, the predicted amount of lateral deviation change, and the steering control amount correction coefficient in the steering control amount limiting unit 13 of the vehicle steering system involved in embodiment 2, and a curve is used to show the mapping when the steering control amount correction coefficient α is calculated based on the absolute value of the steering force.

[0048] In the vehicle steering system involved in embodiment 2, the lateral deviation change prediction amount is set to a value obtained by predicting the lateral deviation change amount, and the lateral deviation change amount is the change amount of the lateral deviation obtained by setting the direction of deviation from the target driving line as a positive value and the direction of following as a negative value. That is, when the lateral deviation change prediction amount is a negative value, the vehicle is in a state close to the target driving line. For example, when the lateral deviation change prediction amount is calculated in the lateral deviation change prediction amount calculation unit 12, the positive or negative of the lateral deviation change prediction amount can be determined based on the relationship between the target driving line obtained from the target driving line setting unit 10 and the vehicle's traveling direction. For example, when the lateral deviation change prediction amount is calculated using formula (1), the yaw angle in the direction of deviation from the target driving line is set to positive. Alternatively, the value of the yaw angle can be calculated based on a predetermined direction, and the lateral speed V can be calculated using formula (1). y , and then decide whether it is positive or negative when outputting it as a predicted amount of lateral deviation change.

[0049] In the steering control amount limiting unit 13 of the vehicle steering system according to the second embodiment, when the predicted lateral deviation variation is large relative to the direction of departure from the target travel line, the steering control amount limit value is set to a larger value or the same value as when the predicted lateral deviation variation is small relative to the direction of departure from the target travel line or when the predicted lateral deviation variation is negative. Therefore, in the case of driver override, the steering control amount in the target travel line following direction is increased only when the predicted lateral deviation variation is large relative to the direction of departure from the target travel line. This effectively notifies the driver of the deviation from the target travel line. Furthermore, when the predicted lateral deviation variation relative to the target travel line is small and the driver intentionally drives on a line different from the target travel line to avoid departing from the target travel line, or when the predicted lateral deviation variation relative to the target travel line is negative and the vehicle is traveling in a direction approaching the target travel line, the steering control amount limit value is reduced, thereby reducing the steering control amount, thereby alleviating the burden and discomfort on the driver.

[0050] Implementation method 3.

[0051] Figure 6 This is a block diagram showing the configuration of a vehicle steering system according to a third embodiment. Figure 6 The vehicle steering system in the embodiment 1 or the vehicle steering system according to the embodiment 2 is different in that the output of the yaw rate detection unit 7 is input to the lateral deviation variation predicted amount calculation unit 12 a of the steering device 1 a .

[0052] The yaw rate detection unit 7 detects the vehicle's yaw rate γ and outputs it to the lateral deviation change prediction amount calculation unit 12a. The lateral deviation change prediction amount calculation unit 12a first calculates the curvature C2 of the target travel line based on the target travel line obtained from the target travel line setting unit 10. Then, the curvature C2 is calculated based on the calculated curvature C2 and the vehicle speed V obtained from the vehicle speed detection unit 5 using the following formula: x The yaw rate component Δγ, which indicates deviation from the target travel line, is calculated using the yaw rate γ obtained from the yaw rate detection unit 7 and outputted as a lateral deviation change prediction amount to the steering control amount limiting unit 13. The positive and negative signs of the lateral deviation change prediction amount are the same as in the second embodiment, with the direction of deviation from the target travel line being the positive direction.

[0053] Δγ=γ-C2V x (2)

[0054] Δγ is the difference between the vehicle's yaw rate and the yaw rate required to rotate along the target travel line, i.e., the value of the yaw rate component that deviates from the target travel line. If the value of the yaw rate component that deviates from the target travel line is used as the predicted lateral deviation change amount, a large predicted lateral deviation change amount indicates that the vehicle is moving laterally within the lane, while a small predicted lateral deviation change amount indicates that the driver is intentionally traveling on a line different from the target travel line. Consequently, the same effects as those of the vehicle steering systems according to Embodiments 1 or 2 can be achieved.

[0055] In addition, the yaw rate detection unit 7 can detect the steering angle of the vehicle and convert it into a yaw angle.

[0056] Implementation method 4.

[0057] Figure 7 This is a block diagram showing the configuration of a vehicle steering system according to a fourth embodiment. Figure 7 The vehicle steering system in the embodiment 1 or the vehicle steering system according to the embodiment 2 is different in that the output of the lateral acceleration detection unit 8 is input to the lateral deviation variation predicted amount calculation unit 12b of the steering device 1b.

[0058] The lateral acceleration detection unit 8 detects the lateral acceleration G of the vehicle. y The lateral deviation change prediction amount calculation unit 12b first calculates the curvature C2 of the target travel line based on the target travel line obtained from the target travel line setting unit 10. Then, the curvature C2 is calculated based on the calculated curvature C2 and the vehicle speed V obtained from the vehicle speed detection unit 5. x and the lateral acceleration G obtained from the lateral acceleration detection unit 8 y , the lateral acceleration component ΔG that deviates from the target driving line is calculated using the following formula: y, and outputs it as the lateral deviation change prediction amount to the steering control amount limiting unit 13. The positive and negative signs of the lateral deviation change prediction amount are the same as those in the second embodiment, with the direction deviating from the target travel line being the positive direction.

[0059] ΔG y =G y -C2V x 2 (3)

[0060] ΔG y The difference between the vehicle's lateral acceleration and the lateral acceleration required to rotate along the target travel line, i.e., the value of the lateral acceleration component that deviates from the target travel line, is used as the predicted lateral deviation variation. A large predicted lateral deviation variation indicates that the vehicle is moving laterally within the lane, while a small predicted lateral deviation variation indicates that the driver is intentionally traveling on a line different from the target travel line. Consequently, the same effects as those of the vehicle steering systems according to Embodiments 1 or 2 can be achieved.

[0061] Implementation method 5.

[0062] Figure 8 This is a block diagram showing the configuration of a vehicle steering system according to a fifth embodiment. Figure 8 The vehicle steering system in the embodiment 1 or the vehicle steering system in the embodiment 2 is different in that the outputs of the yaw rate detection unit 7 and the lateral acceleration detection unit 8 are input to the lateral deviation change predicted amount calculation unit 12c of the steering device 1c.

[0063] The yaw rate detection unit 7 detects the yaw rate γ of the vehicle and outputs it to the lateral deviation change prediction amount calculation unit 12c, which is the same as the vehicle steering system according to the third embodiment. The lateral acceleration detection unit 8 detects the lateral acceleration G of the vehicle. yThis is similar to the vehicle steering system according to Embodiment 4 in that it is output to the lateral deviation change prediction amount calculation unit 12c. The lateral deviation change prediction amount calculation unit 12c uses at least two values ​​of the lateral velocity, the amount of change in lateral deviation, the yaw angle, the yaw rate, and the lateral acceleration to calculate the lateral deviation change prediction amount, and outputs it to the steering control amount limiting unit 13. For example, when all values ​​of the lateral velocity, the amount of change in lateral deviation, the yaw angle, the yaw rate, and the lateral acceleration are used, the values ​​shown in Equations (1), (2), and (3), the amount of change in lateral deviation, and the yaw angle can be added together to form the lateral deviation change prediction amount. When multiple values ​​are selected from the lateral velocity, the amount of change in lateral deviation, the yaw angle, the yaw rate, and the lateral acceleration, the corresponding values ​​can be added together to form the lateral deviation change prediction amount. Furthermore, when calculating the lateral deviation change prediction amount, the signs of the lateral velocity, the amount of change in lateral deviation, the yaw angle, the yaw rate, and the lateral acceleration are similar to those in Embodiment 2, with the direction away from the target course being considered positive. Therefore, it is possible to obtain the same effects as those of the vehicle steering system according to the first or second embodiment.

[0064] Figure 9 It is a diagram showing the hardware configuration of the steering systems 1, 1a, 1b, and 1c according to the first to fifth embodiments. Figure 9 The case where a processor 102 such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor) is used to construct a target driving line setting unit 10, a steering control amount calculation unit 11, a lateral deviation change prediction amount calculation unit 12, 12a, 12b, 12c, a steering control amount limiting unit 13, and a steering control unit 14 of the steering device 1, 1a, 1b, 1c is shown. In this case, the functions of each block of the steering device 1, 1a, 1b, 1c are realized by software, firmware, or a combination of software and firmware. The software or firmware is expressed in the form of a program and stored in the memory 103. The interface 101 performs input and output control of signals of the steering force detection unit 3, the driving path identification unit 4, the vehicle speed detection unit 5, the steering actuator 6, the yaw rate detection unit 7, and the lateral acceleration detection unit 8. In addition, Figure 9 Only the configuration of the steering actuator 6 connected via the interface 101 is shown. The processor 102 implements the functions of each block of the steering devices 1, 1a, 1b, and 1c by executing various processes according to programs stored in the memory 103. The interface 101, processor 102, and memory 103 are interconnected via a bus.

[0065] This application describes various exemplary embodiments, but the various features, forms, and functions described in one or more embodiments are not limited to the application of specific embodiments and can be applied to the embodiments alone or in various combinations.

[0066] Therefore, it is understood that numerous modifications not shown in the examples are also included within the technical scope disclosed in this application, including, for example, modifications, additions, or omissions of at least one component, and extraction of at least one component and combination with components of other embodiments.

[0067] Description of labels

[0068] 1.1a, 1b, 1c Steering device

[0069] 2 Steering input unit

[0070] 3 Steering force detection unit

[0071] 4 Driving path recognition unit

[0072] 5. Vehicle speed detection unit

[0073] 6 Steering actuator

[0074] 7Yaw rate detection unit

[0075] 8Lateral acceleration detection unit

[0076] 10 Target driving line setting unit

[0077] 11 Steering control amount calculation unit

[0078] 12, 12a, 12b, 12c lateral deviation change prediction amount calculation unit

[0079] 13 Steering control amount limiting unit

[0080] 14 Steering control unit

[0081] 20 vehicles

[0082] 21 Direction of travel

[0083] 22 Target driving line

[0084] 101 interface

[0085] 102 processors

[0086] 103 memory.

Claims

1. A steering system for a vehicle, A vehicle steering system is provided for assisting a steering operation so that the vehicle follows a target travel line. The system is characterized by comprising: A steering input unit, which is used by the driver to perform steering operations; a steering force detection unit configured to detect a steering force input to the steering input unit; a steering control amount calculation unit that calculates a steering control amount for causing the vehicle to follow the target travel line; a lateral deviation variation prediction amount calculation unit configured to calculate a lateral deviation variation prediction amount obtained by predicting a lateral deviation variation amount of the vehicle relative to the target travel line; a steering control amount limiting unit that calculates a steering control amount limiting value based on the steering force and the lateral deviation variation predicted amount, and outputs a limited steering control amount obtained by limiting the steering control amount by the steering control amount limiting value; as well as a steering control unit configured to control the steering of the vehicle based on the limited steering control amount, When the absolute value of the steering force is the same, when the absolute value of the lateral deviation variation predicted amount is larger, the steering control amount limiting unit sets the steering control amount limiting value to a larger value or the same value as when the absolute value of the lateral deviation variation predicted amount is smaller.

2. The vehicle steering system according to claim 1, wherein: The lateral deviation variation predicted amount calculation unit calculates the lateral deviation variation predicted amount based on a lateral speed of the vehicle.

3. The vehicle steering system according to claim 1, wherein: The lateral deviation variation predicted amount calculation unit calculates the lateral deviation variation predicted amount based on an amount of change in the lateral deviation between the vehicle and the target travel line.

4. The vehicle steering system according to claim 1, wherein: The lateral deviation variation predicted amount calculation unit calculates the lateral deviation variation predicted amount based on a yaw angle of the vehicle relative to the target travel line.

5. The vehicle steering system according to claim 1, wherein: comprising a yaw rate detection unit for detecting the yaw rate of the vehicle, The lateral deviation variation predicted amount calculation unit calculates the lateral deviation variation predicted amount based on the yaw rate.

6. The vehicle steering system according to claim 1, wherein: comprising a lateral acceleration detection unit for detecting the lateral velocity of the vehicle, The lateral deviation variation predicted amount calculation unit calculates the lateral deviation variation predicted amount based on the lateral acceleration.

7. The vehicle steering system according to claim 1, wherein: The lateral deviation change prediction amount calculation unit calculates the lateral deviation change prediction amount based on at least two values ​​of the vehicle's lateral speed, the change in the lateral deviation between the vehicle and the target travel line, the vehicle's yaw angle relative to the target travel line, the vehicle's yaw rate, and the vehicle's lateral acceleration.

8. The vehicle steering system according to any one of claims 1 to 7, wherein: include: a driving path recognition unit that recognizes a driving path of the vehicle and outputs driving path information; as well as A target traveling line setting unit sets and outputs the target traveling line based on the traveling route information.

9. A steering system for a vehicle, A vehicle steering system is provided for assisting a steering operation so that the vehicle follows a target travel line. The system is characterized by comprising: A steering input unit, which is used by the driver to perform steering operations; a steering force detection unit configured to detect a steering force input to the steering input unit; a steering control amount calculation unit that calculates a steering control amount for causing the vehicle to follow the target travel line; a lateral deviation variation prediction amount calculation unit configured to calculate a lateral deviation variation prediction amount obtained by predicting a lateral deviation variation amount, the lateral deviation variation amount being a variation amount of the lateral deviation obtained by setting a positive value for a direction in which the vehicle deviates from the target travel line and a negative value for a direction in which the vehicle follows the target travel line; a steering control amount limiting unit that calculates a steering control amount limiting value based on the steering force and the lateral deviation variation predicted amount, and outputs a limited steering control amount obtained by limiting the steering control amount by the steering control amount limiting value; as well as a steering control unit configured to control the steering of the vehicle based on the limited steering control amount, When the value of the steering force is the same, when the predicted lateral deviation change amount is larger relative to the positive direction, the steering control amount limiting unit sets the steering control amount limiting value to a larger value or the same value as when the predicted lateral deviation change amount is smaller relative to the positive direction.

10. The vehicle steering system according to claim 9, wherein: The lateral deviation variation predicted amount calculation unit calculates the lateral deviation variation predicted amount based on a lateral speed of the vehicle.

11. The vehicle steering system according to claim 9, wherein: The lateral deviation variation predicted amount calculation unit calculates the lateral deviation variation predicted amount based on an amount of change in the lateral deviation between the vehicle and the target travel line.

12. The vehicle steering system according to claim 9, wherein: The lateral deviation variation predicted amount calculation unit calculates the lateral deviation variation predicted amount based on a yaw angle of the vehicle relative to the target travel line.

13. The vehicle steering system according to claim 9, wherein: comprising a yaw rate detection unit for detecting the yaw rate of the vehicle, The lateral deviation variation predicted amount calculation unit calculates the lateral deviation variation predicted amount based on the yaw rate.

14. The vehicle steering system according to claim 9, wherein: comprising a lateral acceleration detection unit for detecting the lateral velocity of the vehicle, The lateral deviation variation predicted amount calculation unit calculates the lateral deviation variation predicted amount based on the lateral acceleration.

15. The vehicle steering system according to claim 9, wherein: The lateral deviation change prediction amount calculation unit calculates the lateral deviation change prediction amount based on at least two values ​​of the vehicle's lateral speed, the change in the lateral deviation between the vehicle and the target travel line, the vehicle's yaw angle relative to the target travel line, the vehicle's yaw rate, and the vehicle's lateral acceleration.

16. The vehicle steering system according to any one of claims 9 to 15, wherein: include: a driving path recognition unit that recognizes a driving path of the vehicle and outputs driving path information; as well as A target traveling line setting unit sets and outputs the target traveling line based on the traveling route information.

Images