Steering control device

Abstract

To suppress periodic movement of a steering when a vehicle passes an irregularity on a road surface.SOLUTION: A steering control device 10 includes: a feedforward steering angle determination part 11 that determines a feedforward steering angle corresponding to a target yaw rate; a feedback steering angle determination part 12 that determines a feedback steering angle on the basis of a yaw rate detected by a yaw rate sensor 3 and a steering angle detected by a steering angle sensor 4; a target steering angle determination part 14 that determines a target steering angle of a vehicle 1 on the basis of the feedforward steering angle and the feedback steering angle; and a correction part 13 that performs feedback steering angle fixation control of correcting the feedback steering angle output to the target steering angle determination part 14 to a fixation value when the yaw rate detected by the yaw rate sensor 3 exceeds a target yaw rate range including the target yaw rate and the steering angle detected by the steering angle sensor 4 periodically moves.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a steering control device.

Background Art

[0002] Patent Document 1 describes a technique for decelerating a vehicle when it is detected that the vehicle is traveling on a road surface unevenness.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Some steering control devices such as a lane departure prevention device perform steering control of a vehicle so that the yaw rate of the vehicle detected by a yaw rate sensor becomes a target yaw rate. In such a steering control device, a target steering angle is determined by a feedforward steering angle corresponding to the target yaw rate and a feedback steering angle determined based on the yaw rate detected by the yaw rate sensor and the steering angle detected by the steering angle sensor, and steering control of the vehicle is performed based on the determined target steering angle. Here, when the vehicle passes over a road surface unevenness, a vertical disturbance occurs in the vehicle, and the disturbance is applied to the yaw rate sensor that detects the yaw rate of the vehicle. When such a disturbance is applied to the yaw rate sensor, the yaw rate detected by the yaw rate sensor greatly deviates from the target yaw rate. Therefore, a target steering angle for reducing this deviation is determined, and the vehicle makes a large turn due to the steering control of the vehicle based on the determined target steering angle. Thereafter, a target steering angle in the right turning direction and a target steering angle in the left turning direction for returning the direction of the vehicle are repeated in a short time, and a phenomenon occurs in which the steering periodically moves in the right steering direction and the left steering direction.

[0005] Therefore, an object of the present invention is to provide a steering control device that can suppress the periodic movement of the steering when the vehicle passes over unevenness on the road surface.

Means for Solving the Problems

[0006] The steering control device according to the present invention is mounted on a vehicle having a yaw rate sensor for detecting a yaw rate and a steering angle sensor for detecting a steering angle, and is a steering control device that controls the steering of the vehicle so that the yaw rate of the vehicle becomes a target yaw rate. The steering control device includes a feedforward steering angle determination unit that determines a feedforward steering angle corresponding to the target yaw rate, a feedback steering angle determination unit that determines a feedback steering angle based on the yaw rate detected by the yaw rate sensor and the steering angle detected by the steering angle sensor, a target steering angle determination unit that determines a target steering angle of the vehicle based on the feedforward steering angle and the feedback steering angle, and a correction unit that performs feedback steering angle fixed control for correcting the feedback steering angle output to the target steering angle determination unit to a fixed value when the yaw rate detected by the yaw rate sensor exceeds a target yaw rate range including the target yaw rate and the steering angle detected by the steering angle sensor moves periodically.

[0007] In this steering control device, by performing steering control of the vehicle so that the yaw rate of the vehicle becomes the target yaw rate, for example, the vehicle can be made to travel so that the vehicle travels at a predetermined position in the lane or does not deviate from the lane. And when the yaw rate detected by the yaw rate sensor exceeds the target yaw rate range and the steering angle detected by the steering angle sensor moves periodically, feedback steering angle fixed control for correcting the feedback steering angle output to the target steering angle determination unit to a fixed value is performed, so that the periodic movement of the steering when the vehicle passes over unevenness on the road surface can be suppressed.

[0008] The feedforward steering angle determination unit may set a target yaw rate based on the curvature of the lane in which the vehicle is traveling and the vehicle speed of the vehicle. In this steering control device, since the target yaw rate is set based on the curvature of the lane and the vehicle speed, the feedforward steering angle can be appropriately calculated.

[0009] The feedforward rudder angle determination unit may set a target yaw rate so that the vehicle does not deviate from the lane. In this steering control device, since the target yaw rate is set so that the vehicle does not deviate from the lane, it is possible to appropriately suppress the vehicle from deviating from the lane.

[0010] The correction unit may correct the feedback rudder angle to the average value of the feedback rudder angles in the most recent setting period in the feedback rudder angle fixed control. In this steering control device, in the feedback rudder angle fixed control, since the feedback rudder angle is corrected to the average value of the feedback rudder angles in the most recent setting period, it is possible to suppress the behavior of the vehicle from becoming unstable before and after the feedback rudder angle fixed control.

[0011] When the displacement speed of the target rudder angle exceeds the set speed, the target rudder angle determination unit limits the displacement speed of the target rudder angle, and when the target rudder angle determination unit further limits the displacement speed of the target rudder angle, the correction unit may perform feedback rudder angle fixed control. In this steering control device, by limiting the displacement speed of the target rudder angle when the displacement speed of the target rudder angle exceeds the set speed, it is possible to suppress the behavior of the vehicle from becoming unstable. Here, when the vehicle passes through the unevenness of the road surface and a disturbance is applied to the yaw rate sensor, the displacement speed of the target rudder angle tends to become excessive. Therefore, the feedback rudder angle fixed control is also performed on the condition that the displacement speed of the target rudder angle has been limited because the displacement speed of the target rudder angle exceeds the set speed. Thereby, it is possible to more appropriately suppress the steering from periodically moving when the vehicle passes through the unevenness of the road surface.

[0012] When the target rudder angle determination unit determines that the target rudder angle exceeds the set value, it limits the displacement speed of the target rudder angle. The correction unit may further perform feedback rudder angle fixed control when the target rudder angle determination unit limits the displacement speed of the target rudder angle. In this steering control device, by limiting the displacement speed of the target rudder angle when the target rudder angle exceeds the set value, it is possible to suppress the instability of the vehicle behavior. When the vehicle passes over the unevenness of the road surface and a disturbance is applied to the yaw rate sensor, the target rudder angle tends to become excessive. Therefore, feedback rudder angle fixed control is also performed on the condition that the displacement speed of the target rudder angle is limited because the target rudder angle exceeds the set value. As a result, it is possible to more appropriately suppress the periodic movement of the steering when the vehicle passes over the unevenness of the road surface.

[0013] The steering control device may cancel the feedback rudder angle fixed control when a set time has elapsed after performing the feedback rudder angle fixed control. In this steering control device, by canceling the feedback rudder angle fixed control when a set time has elapsed after performing the feedback rudder angle fixed control, it is possible to cancel the feedback rudder angle fixed control without determining whether the disturbance applied to the yaw rate sensor has subsided due to the vehicle passing over the unevenness of the road surface. As a result, the control can be simplified.

Advantages of the Invention

[0014] According to the present invention, it is possible to suppress the periodic movement of the steering when the vehicle passes over the unevenness of the road surface.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0017] [First Embodiment] FIG. 1 is a schematic diagram showing a steering control device 10 according to the first embodiment. As shown in FIG. 1, the steering control device 10 according to the present embodiment is mounted on the vehicle 1 and performs steering control of the vehicle 1. The steering control device 10 performs steering control of the vehicle 1 so that, for example, the vehicle 1 does not deviate from the lane or the vehicle 1 travels at a predetermined position in the vehicle width direction of the lane.

[0018] The vehicle 1 includes a camera 2, a yaw rate sensor 3, a rudder angle sensor 4, a vehicle speed sensor 5, a steering actuator 6, and a steering control device 10.

[0019] The camera 2 images the front of the vehicle 1. The camera 2 may be a monocular camera or a stereo camera. The stereo camera has two imaging units arranged to reproduce binocular parallax. The imaging information of the stereo camera also includes information in the depth direction. The camera 2 outputs the captured imaging image to the steering control device 10.

[0020] The yaw rate sensor 3 detects the yaw rate of the vehicle 1. The yaw rate is the rotational angular velocity around the vertical axis of the vehicle 1. As the yaw rate sensor 3, for example, a gyro sensor is used. The yaw rate sensor 3 outputs information indicating the detected yaw rate of the vehicle 1 to the steering control device 10.

[0021] The steering angle sensor 4 detects the steering angle (the amount of rotation of the steering axis) of the vehicle 1. The steering angle sensor 4 outputs information indicating the detected steering angle of the vehicle 1 to the steering control device 10.

[0022] The vehicle speed sensor 5 detects the vehicle speed (speed) of the vehicle 1. As the vehicle speed sensor 5, for example, a wheel speed sensor provided on the drive shaft of the vehicle 1 and detecting the rotational speed of the wheels is used. The vehicle speed sensor 5 outputs information indicating the detected vehicle speed of the vehicle 1 to the steering control device 10.

[0023] The steering actuator 6 controls the drive of the electric power steering system according to a control signal from the steering control device 10. By controlling the drive of the electric power steering system, the steering angle of the vehicle 1 is controlled.

[0024] The steering control device 10 is, for example, an electronic control unit (ECU: Electronic Control Unit) having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. In the steering control device 10, for example, a program stored in the ROM is loaded into the RAM and executed by the CPU to execute various controls. The steering control device 10 may be constituted by a single electronic control unit or may be constituted by a plurality of electronic control units.

[0025] The steering control device 10 controls the steering of the vehicle 1 so that the yaw rate of the vehicle 1 becomes the target yaw rate. As a functional configuration, the steering control device 10 includes a feedforward steering angle determination unit 11, a feedback steering angle determination unit 12, a correction unit 13, a target steering angle determination unit 14, a yaw rate determination unit 15, and a steering determination unit 16.

[0026] The feedforward steering angle determination unit 11 determines a feedforward steering angle corresponding to the target yaw rate. For example, the feedforward steering angle determination unit 11 sets the target yaw rate, determines the target yaw rate based on the curvature of the lane in which the vehicle 1 is traveling and the vehicle speed of the vehicle 1, and determines a feedforward steering angle corresponding to the target yaw rate. Then, the feedforward steering angle determination unit 11 outputs the determined feedforward steering angle to the target steering angle determination unit 14.

[0027] The curvature of the lane in which the vehicle 1 is traveling is obtained by analyzing the captured image captured by the camera 2. Note that the curvature of the lane in which the vehicle 1 is traveling may be obtained by specifying the position of the vehicle 1 with a GPS or the like and comparing the specified position of the vehicle 1 with the map information. The vehicle speed of the vehicle 1 is obtained from the vehicle speed sensor 5. The target yaw rate γ T may be, for example, a yaw rate for the vehicle 1 to travel at the center in the width direction of the lane, or a yaw rate for returning the vehicle 1 to the center side in the width direction of the lane so that the vehicle 1 does not deviate from the lane when the vehicle 1 is about to deviate from the lane. The feedforward steering angle is the steering angle for making the yaw rate of the vehicle 1 the target yaw rate γ T to be.

[0028] The feedback steering angle determination unit 12 determines a feedback steering angle based on the yaw rate γ of the vehicle 1 detected by the yaw rate sensor 3 and the steering angle of the vehicle 1 detected by the steering angle sensor 4. For example, the feedback steering angle determination unit 12 determines the steering angle corresponding to the yaw rate γ of the vehicle 1 detected by the yaw rate sensor 3 and the target yaw rate γ TDetermine the difference from the rudder angle corresponding thereto as the feedback rudder angle. Then, the feedback rudder angle determination unit 12 outputs the determined feedback rudder angle to the correction unit 13.

[0029] The correction unit 13 corrects the feedback rudder angle output from the feedback rudder angle determination unit 12 as necessary and outputs it to the target rudder angle determination unit 14. The details of the correction unit 13 will be described later.

[0030] The target rudder angle determination unit 14 determines the target rudder angle of the vehicle 1 based on the feedforward rudder angle and the feedback rudder angle. For example, the target rudder angle determination unit 14 sets the sum of the feedforward rudder angle determined by the feedforward rudder angle determination unit 11 and the feedback rudder angle determined by the feedback rudder angle determination unit 12 as the target rudder angle. Also, when the feedback rudder angle is corrected by the correction unit 13, the sum of the feedforward rudder angle determined by the feedforward rudder angle determination unit 11 and the feedback rudder angle corrected by the correction unit 13 is set as the target rudder angle. Then, the target rudder angle determination unit 14 performs steering control of the vehicle 1 by driving and controlling the steering actuator 6 based on the determined target rudder angle.

[0031] By the way, when the displacement speed of the target rudder angle becomes excessive, if the steering control of the vehicle 1 is performed with the target rudder angle as it is, the behavior of the vehicle 1 may become unstable. The displacement speed of the target rudder angle is the displacement amount of the target rudder angle per unit. Similarly, when the target rudder angle becomes excessive, if the steering control of the vehicle 1 is performed with the target rudder angle as it is, the behavior of the vehicle 1 may become unstable.

[0032] Therefore, as shown in FIG. 2, when the displacement speed of the target steering angle exceeds the set speed, or when the target steering angle exceeds the set value, the target steering angle determination unit 14 limits the displacement speed of the target steering angle. FIG. 2 is a graph showing an example of the relationship between time and the target steering angle. In FIG. 2, the dashed line indicates the target steering angle when the displacement speed is not limited, and the solid line indicates the target steering angle when the displacement speed is limited. The set speed of the change speed of the target steering angle and the set value of the target steering angle, which are the conditions for limiting the displacement speed of the target steering angle, are not particularly limited. For example, the set speed of the change speed of the target steering angle can be a speed within a range where the behavior of the vehicle 1 does not become unstable when performing the steering control of the vehicle 1 based on the target steering angle. Similarly, the set value of the target steering angle can be a value within a range where the behavior of the vehicle 1 does not become unstable when performing the steering control of the vehicle 1 based on the target steering angle. Note that the displacement speed of the target steering angle can be easily obtained, for example, by recording the past target steering angles.

[0033] Here, referring to FIGS. 3 and 4, the state when the vehicle 1 passes over the unevenness of the road surface will be described. FIG. 3 is a graph showing an example of the relationship between time and the yaw rate. FIG. 4 is a graph showing an example of the relationship between time and the feedback steering angle determined by the feedback steering angle determination unit. In FIGS. 3 and 4, the timing when the vehicle 1 passes over the unevenness of the road surface is indicated by time T1. FIG. 4 shows an example of the relationship between time and the feedback steering angle in a partial time period of FIG. 3. The unevenness of the road surface is, for example, unevenness such as joints, rumble strips, small stones, etc., over which the vehicle 1 passes and the vehicle 1 sways in the vertical direction.

[0034] As shown in FIGS. 3 and 4, when the vehicle 1 passes over unevenness and vertical disturbances occur in the vehicle 1, disturbances (shocks) are also applied to the yaw rate sensor 3, and the yaw rate γ detected by the yaw rate sensor 3 rapidly increases on the plus side (or minus side). As a result, the feedback steering angle determined by the feedback steering angle determination unit 12 also rapidly increases on the plus side (or minus side). Therefore, the target steering angle determination unit 14 determines the target steering angle so that the steering moves greatly in the left steering direction (or right steering direction), and drives and controls the steering actuator 6. As a result, the vehicle 1 starts to turn left (or right). Then, the yaw rate sensor 3 detects a yaw rate γ on the minus side (or plus side), which is the opposite direction to when the vehicle 1 passes over the unevenness. As a result, the feedback steering angle determination unit 12 determines the feedback steering angle on the minus side (or plus side), and the target steering angle determination unit 14 determines the target steering angle so that the steering moves in the right steering direction (or left steering direction), and drives and controls the steering actuator 6. That is, the target steering angle determination unit 14 determines the target steering angle so as to return the direction of the vehicle 1 that has turned due to passing over the unevenness, and drives and controls the steering actuator 6. Then, by repeating such processing operations in a short period of time, a phenomenon in which the steering moves periodically occurs. The periodic movement of the steering means that the steering repeats movement in the right steering (right rotation) direction and movement in the left steering (left rotation) direction in a short period of time.

[0035] The yaw rate determination unit 15 determines whether the yaw rate γ detected by the yaw rate sensor 3 exceeds a target yaw rate range γ T including the target yaw rate γ R . The target yaw rate range γ R is a range from a yaw rate smaller than the target yaw rate γ T to a yaw rate larger than the target yaw rate γ T . The upper limit value and the lower limit value of the target yaw rate range γ R are not particularly limited. For example, the target yaw rate range γ RIt includes the yaw rate γ detected by the yaw rate sensor 3 when no disturbance is applied to the yaw rate sensor 3, and can be set to a range that does not include the yaw rate γ detected by the yaw rate sensor 3 when a disturbance is applied to the yaw rate sensor 3 as the vehicle 1 passes over road surface unevenness.

[0036] The steering determination unit 16 determines whether the steering angle detected by the steering angle sensor 4 is moving periodically, that is, whether the steering is moving periodically. When the steering angle detected by the steering angle sensor 4 repeatedly switches between the right steering direction (plus direction) and the left steering direction (minus direction) in a short time, the steering determination unit 16 determines that the steering angle detected by the steering angle sensor 4 is moving periodically, that is, the steering is moving periodically.

[0037] The correction unit 13 determines whether the yaw rate γ detected by the yaw rate sensor 3 exceeds the target yaw rate range γ T including the target yaw rate γ R and whether the steering angle detected by the steering angle sensor 4 moves periodically. Whether the yaw rate γ detected by the yaw rate sensor 3 exceeds the target yaw rate range γ T including the target yaw rate γ R is determined based on the determination result of the yaw rate determination unit 15. Also, whether the steering angle detected by the steering angle sensor 4 moves periodically is determined based on the determination result of the steering determination unit 16. Then, when the yaw rate γ detected by the yaw rate sensor 3 exceeds the target yaw rate range γ T including the target yaw rate γ R and the steering angle detected by the steering angle sensor 4 moves periodically, the feedback steering angle fixed control is performed. The feedback steering angle fixed control is a control that corrects the feedback steering angle output to the target steering angle determination unit 14 to a fixed value. Further, when a set time elapses after the correction unit 13 performs the feedback steering angle fixed control (after starting the feedback steering angle fixed control), the feedback steering angle fixed control is released.

[0038] FIG. 5 is a graph showing an example of the relationship between time and the feedback rudder angle corrected by the correction unit. In FIGS. 4 and 5, the timing at which the feedback rudder angle fixed control is started is indicated by time T2, and the timing at which the feedback rudder angle fixed control is released is indicated by time T3. When the feedback rudder angle fixed control is not being executed (before and after the execution of the feedback rudder angle fixed control), the correction unit 13 outputs the feedback rudder angle output from the feedback rudder angle determination unit 12 as it is to the target rudder angle determination unit 14. Therefore, the target rudder angle determination unit 14 determines the target rudder angle based on the feedback rudder angle determined by the feedback rudder angle determination unit 12. On the other hand, as shown in FIG. 5, during the execution of the feedback rudder angle fixed control, the correction unit 13 corrects the feedback rudder angle output from the feedback rudder angle determination unit 12 to a fixed value and outputs it to the target rudder angle determination unit 14. Therefore, the target rudder angle determination unit 14 does not determine the target rudder angle based on the feedback rudder angle determined by the feedback rudder angle determination unit 12, but determines the target rudder angle based on the feedback rudder angle corrected to a fixed value by the correction unit 13.

[0039] The fixed value, which is the correction value of the feedback rudder angle, is not particularly limited. For example, the fixed value, which is the correction value of the feedback rudder angle, may be the average value of the feedback rudder angles in the most recent setting period of the feedback rudder angle fixed control, or may be the most recent feedback rudder angle of the feedback rudder angle fixed control. The setting period is not particularly limited, but can be, for example, about 3 seconds. The average value of the feedback rudder angles in the most recent setting period of the feedback rudder angle fixed control can be easily obtained, for example, by recording the past feedback rudder angles.

[0040] Next, with reference to FIG. 6, an example of the processing operation of the steering control device 10 will be described. FIG. 6 is a flowchart showing an example of the processing operation of the steering control device according to the first embodiment.

[0041] As shown in FIG. 6, first, the steering control device 10 detects the yaw rate γ of the vehicle 1 by the yaw rate sensor 3, the steering angle of the vehicle 1 by the steering angle sensor 4, the vehicle speed of the vehicle 1 by the vehicle speed sensor 5, and the curvature of the lane in which the vehicle 1 is traveling (step S1). The order of these detections is not particularly limited, and they may be performed in any order, or some or all of them may be performed simultaneously.

[0042] Next, the steering control device 10 determines the feedforward steering angle and the feedback steering angle (step S2). Then, the steering control device 10 determines whether the yaw rate γ detected by the yaw rate sensor 3 exceeds the target yaw rate range γ R (step S3). When it is determined that the yaw rate γ detected by the yaw rate sensor 3 does not exceed the target yaw rate range γ R (step S3: NO), the steering control device 10 determines the target steering angle based on the feedforward steering angle determined in step S2 and the feedback steering angle determined in step S2, and controls the steering of the vehicle 1 with the determined target steering angle (step S8). If the displacement speed of the target steering angle determined in step S8 exceeds the set speed, or if the target steering angle determined in step S8 exceeds the set value, the steering control device 10 limits the displacement speed of the target steering angle. Then, the steering control device 10 once ends the process and repeats from step S1 again.

[0043] The yaw rate γ detected by the yaw rate sensor 3 is the target yaw rate range γ RWhen it is determined that it has exceeded (Step S3: YES), the steering control device 10 determines whether the steering angle detected by the steering angle sensor 4 is moving periodically (Step S4). Note that Step S3 and Step S4 may be performed in the reverse order or simultaneously. When it is determined that the steering angle detected by the steering angle sensor 4 is not moving periodically (Step S4: NO), the steering control device 10 determines the target steering angle based on the feedforward steering angle determined in Step S2 and the feedback steering angle determined in Step S2, and controls the steering of the vehicle 1 with the determined target steering angle (Step S8). Then, the steering control device 10 once terminates the process and repeats from Step S1 again.

[0044] When it is determined that the steering angle detected by the steering angle sensor 4 is moving periodically (Step S4: YES), the steering control device 10 performs feedback steering angle fixed control to correct the feedback steering angle output to the target steering angle determination unit 14 to a fixed value (Step S5). In Step S5, the steering control device 10 determines the target steering angle based on the feedforward steering angle determined in Step S2 and the feedback steering angle corrected to a fixed value, and controls the steering of the vehicle 1 with the determined target steering angle. Then, the steering control device 10 continues the feedback steering angle fixed control until the set period elapses after performing the feedback steering angle fixed control (Step S6).

[0045] When the set period elapses after performing the feedback steering angle fixed control (Step S6: YES), the steering control device 10 releases the feedback steering angle fixed control (Step S7), determines the target steering angle based on the feedforward steering angle determined in Step S2 and the feedback steering angle determined in Step S2, and controls the steering of the vehicle 1 with the determined target steering angle (Step S8). Then, the steering control device 10 once terminates the process and repeats from Step S1 again.

[0046] As described above, in the steering control device 10 according to the present embodiment, by performing steering control of the vehicle 1 so that the yaw rate of the vehicle 1 becomes the target yaw rate, for example, the vehicle 1 can be made to travel at a predetermined position in the lane or the vehicle 1 can be made to travel without deviating from the lane. Then, when the yaw rate detected by the yaw rate sensor 3 exceeds the target yaw rate range and the steering angle detected by the steering angle sensor 4 moves periodically, feedback steering angle fixing control for correcting the feedback steering angle output to the target steering angle determination unit 14 to a fixed value is performed, so that it is possible to suppress the periodic movement of the steering when the vehicle 1 passes over the unevenness of the road surface.

[0047] Further, in this steering control device 10, since the target yaw rate is set based on the curvature of the lane and the vehicle speed of the vehicle 1, the feedforward steering angle can be appropriately calculated.

[0048] Further, in this steering control device 10, since the target yaw rate is set so that the vehicle 1 does not deviate from the lane, it is possible to appropriately suppress the vehicle 1 from deviating from the lane.

[0049] Further, in this steering control device 10, in the feedback steering angle fixing control, since the feedback steering angle is corrected to the average value of the feedback steering angles in the most recent setting period, it is possible to suppress the behavior of the vehicle 1 from becoming unstable.

[0050] Further, in this steering control device 10, by limiting the displacement speed of the target steering angle when the displacement speed of the target steering angle exceeds the set speed, it is possible to suppress the behavior of the vehicle 1 from becoming unstable.

[0051] Further, in this steering control device 10, by limiting the displacement speed of the target steering angle when the target steering angle exceeds the set value, it is possible to suppress the behavior of the vehicle 1 from becoming unstable.

[0052] In addition, in this steering control device 10, when the set time has elapsed after performing the feedback steering angle fixed control, the feedback steering angle fixed control is released, so that without determining whether the disturbance applied to the yaw rate sensor 3 has subsided due to the vehicle 1 passing over the unevenness of the road surface, the feedback steering angle fixed control can be released. Thereby, simplification of the control can be achieved.

[0053] [Second Embodiment] Next, a second embodiment of the present invention will be described. The second embodiment is basically the same as the first embodiment, but the content of the feedback steering angle fixed control by the steering control unit is different from that of the first embodiment. Therefore, hereinafter, only the matters different from the first embodiment will be described, and the description of the matters the same as those of the first embodiment will be omitted.

[0054] FIG. 7 is a schematic diagram showing a steering control device according to the second embodiment. As shown in FIG. 7, the steering control device 10A according to the present embodiment is mounted on a vehicle 1A and performs steering control of the vehicle 1A. The steering control device 10A includes a camera 2, a yaw rate sensor 3, a steering angle sensor 4, a vehicle speed sensor 5, a steering actuator 6, and a steering control device 10A.

[0055] Functionally, the steering control device 10A includes a feedforward steering angle determination unit 11, a feedback steering angle determination unit 12, a correction unit 13A, a target steering angle determination unit 14, a yaw rate determination unit 15, and a steering determination unit 16.

[0056] The correction unit 13A is basically the same as the correction unit 13A of the first embodiment, and a part of the conditions for performing the feedback steering angle fixed control is different from that of the correction unit 13 of the first embodiment. The target steering angle determination unit 14, as in the first embodiment, limits the displacement speed of the target steering angle when the displacement speed of the target steering angle exceeds the set speed or when the target steering angle exceeds the set value. And the correction unit 13A is such that the yaw rate γ detected by the yaw rate sensor 3 is within the target yaw rate range γ including the target yaw rate γ T including the target yaw rate γ RWhen it exceeds and the rudder angle detected by the rudder angle sensor 4 moves periodically, and further when the target rudder angle determination unit 14 limits the displacement speed of the target rudder angle, feedback rudder angle fixed control is performed to correct the feedback rudder angle output to the target rudder angle determination unit 14 to a fixed value. That is, in addition to the condition under which the correction unit 13A of the first embodiment performs feedback rudder angle fixed control, when the displacement speed of the target rudder angle exceeds the set speed or when the target rudder angle exceeds the set value, and the displacement speed of the target rudder angle is limited, feedback rudder angle fixed control is also performed as a condition.

[0057] Next, with reference to FIG. 8, an example of the processing operation of the steering control device 10A will be described. FIG. 8 is a flowchart showing an example of the processing operation of the steering control device according to the second embodiment.

[0058] As shown in FIG. 8, first, the steering control device 10A performs steps S1 to S4 in the same manner as in the first embodiment. And when it is determined that the rudder angle detected by the rudder angle sensor 4 in step S4 moves periodically (step S4: YES), the steering control device 10A determines whether the displacement speed of the target rudder angle determined in step S8 up to the previous time exceeds the set speed or whether the target rudder angle determined in step S8 up to the previous time exceeds the set value, thereby determining whether the displacement speed of the target rudder angle is limited (step S11). And when it is determined that the displacement speed of the target rudder angle is not limited (step S11: NO), the steering control device 10A determines the target rudder angle based on the feedforward rudder angle and the feedback rudder angle determined in step S2, and controls the steering of the vehicle 1 with the determined target rudder angle (step S8). Then, the steering control device 10A once ends the process and repeats from step S1 again.

[0059] When it is determined that the displacement speed of the target rudder angle is limited (step S11: YES), the steering control device 10A performs feedback rudder angle fixed control to correct the feedback rudder angle output to the target rudder angle determination unit 14 to a fixed value (step S5). Then, the steering control device 10A performs steps S6 to S8 in the same manner as in the first embodiment.

[0060] As described above, in the steering control device 10A according to the present embodiment, when the vehicle 1 passes through the unevenness of the road surface and a disturbance is applied to the yaw rate sensor 3, the displacement speed of the target steering angle tends to become excessive. Therefore, as a further condition, when the displacement speed of the target steering angle exceeds the set speed and the displacement speed of the target steering angle is limited, feedback steering angle fixed control is performed. Thereby, when the vehicle 1 passes through the unevenness of the road surface, it is possible to more appropriately suppress the periodic movement of the steering.

[0061] Further, in this steering control device 10A, when the vehicle 1 passes through the unevenness of the road surface and a disturbance is applied to the yaw rate sensor 3, the target steering angle tends to become excessive. Therefore, as a further condition, when the target steering angle exceeds the set value and the displacement of the target steering angle is limited, feedback steering angle fixed control is performed. Thereby, when the vehicle 1 passes through the unevenness of the road surface, it is possible to more appropriately suppress the periodic movement of the steering.

[0062] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and may be modified without changing the gist described in each claim, or may be applied to other things.

[0063] For example, in the above embodiment, the steering control unit has been described as limiting the displacement speed of the target steering angle when the displacement speed of the target steering angle exceeds the set speed or when the target steering angle exceeds the set value. However, even in such a case, it may not limit the displacement speed of the target steering angle. Further, in such a case, instead of limiting the displacement speed of the target steering angle, correction for limiting the displacement speed of the feedback steering angle output to the target steering angle determination unit may be performed in a correction unit or the like.

Description of reference numerals

[0064] 1... Vehicle, 1A... Vehicle, 2... Camera, 3... Yaw rate sensor, 4... Steering angle sensor, 5... Vehicle speed sensor, 6... Steering actuator, 10... Steering control device, 10A... Steering control device, 11... Feedforward steering angle determination unit, 12... Feedback steering angle determination unit, 13... Correction unit, 13A... Correction unit, 14... Target steering angle determination unit, 15... Yaw rate determination unit, 16... Steering determination unit, γ... Yaw rate, γ R ... Target yaw rate range, γ T ... Target yaw rate.

Claims

1. A steering control device mounted on a vehicle having a yaw rate sensor for detecting a yaw rate and a steering angle sensor for detecting a steering angle, the steering control device steering and controlling the vehicle so that the yaw rate of the vehicle becomes a target yaw rate, a feedforward steering angle determination unit that determines a feedforward steering angle corresponding to the target yaw rate, a feedback steering angle determination unit that determines a feedback steering angle based on the yaw rate detected by the yaw rate sensor and the steering angle detected by the steering angle sensor, a target steering angle determination unit that determines a target steering angle of the vehicle based on the feedforward steering angle and the feedback steering angle, and a correction unit that performs feedback steering angle fixing control for correcting the feedback steering angle output to the target steering angle determination unit to a fixed value when the yaw rate detected by the yaw rate sensor exceeds a target yaw rate range including the target yaw rate and the steering angle detected by the steering angle sensor moves periodically. Steering control device.

2. The feedforward steering angle determination unit sets the target yaw rate based on the curvature of the lane in which the vehicle is traveling and the vehicle speed of the vehicle. The steering control device according to claim 1.

3. The feedforward steering angle determination unit sets the target yaw rate so that the vehicle does not deviate from the lane. The steering control device according to claim 2.

4. In the feedback steering angle fixing control, the correction unit corrects the feedback steering angle to an average value of the feedback steering angles in the most recent setting period. The steering control device according to any one of claims 1 to 3.

5. When the displacement speed of the target steering angle exceeds a set speed, the target steering angle determination unit limits the displacement speed of the target steering angle. When the target steering angle determination unit limits the displacement speed of the target steering angle, the correction unit further performs the feedback steering angle fixing control. The steering control device according to any one of claims 1 to 4.

6. When the target steering angle exceeds a set value, the target steering angle determination unit limits the displacement speed of the target steering angle. When the target steering angle determination unit limits the displacement speed of the target steering angle, the correction unit further performs the feedback steering angle fixing control. The steering control device according to any one of claims 1 to 5.

7. When a set time has elapsed after the feedback rudder angle fixed control is performed, the steering control device releases the feedback rudder angle fixed control. The steering control device according to any one of claims 1 to 6.

Images