Lane Departure Prevention Device

Abstract

To provide a lane deviation suppression device which improves practicability.SOLUTION: A DSECU executes lane deviation warning of actuating a vibration device and steering support of controlling a motor for steering so as to prevent deviation of own vehicle from the lane when detecting that the own vehicle is deviated from a central part to an end side in a lane traverse direction by a predetermined distance or more, and degenerates the form of the steering support or prohibits the steering support when a steering torque TR is equal to a threshold TRth or more. The DSECU degenerates the form of the steering support or prohibits the steering support when the steering torque TR is equal to a first torque T1 or more, in the state of not executing the lane deviation warning, and degenerates the form of the steering support or prohibits the steering support when the steering torque TR is equal to or more than a second torque T2 larger than the first torque T1, in the state of executing the lane deviation warning.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a lane departure prevention device that prevents a host vehicle from departing from a lane (allows the host vehicle to travel along the lane). [Background technology]

[0002] 2. Description of the Related Art Conventionally, there are known devices (hereinafter, referred to as "conventional devices") that prevent a vehicle from departing from a lane (see, for example, Patent Document 1 below).

[0003] The conventional device includes a drive device that drives a steering mechanism to change the steering angle, and a control device that controls the drive device. The control device recognizes the boundary (division line) between the lane in which the vehicle is traveling and the adjacent lane or road edge based on original image data representing an image obtained by photographing the foreground of the vehicle (hereinafter referred to as the "original image"). The control device then controls the drive device so that the vehicle does not deviate from the lane. Hereinafter, this control is referred to as "steering assistance." However, if a steering torque equal to or greater than a threshold value is acting on the steering wheel, the control device prohibits steering assistance (sets it to an infeasible state). That is, in this case, there is a possibility that the driver is intentionally trying to deviate from the lane (e.g., change lanes), so the driver's steering operation (manual operation) is prioritized.

[0004] Furthermore, the conventional device is equipped with a vibration device that vibrates the steering wheel. When the control device detects, based on the raw image data, that the vehicle is approaching the edge (the lane marking side) in the cross direction of the lane, it activates the vibration device to vibrate the steering wheel and notify the driver. Hereinafter, this control is referred to as "lane departure warning." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-116693 A Summary of the Invention

[0006] For example, when steering assistance is being performed (or when steering assistance can be performed (enabled state)), and the vehicle approaches slightly to the left of the center of the lane, the driver may lightly operate the steering wheel to pull the vehicle back toward the center of the lane (see FIG. 5). In this case, if the steering torque does not exceed the above threshold, the steering assistance (enabled state) will continue. Note that in this example, since the driver is not intentionally trying to deviate from the lane, it is desirable to continue the steering assistance (enabled state).

[0007] Here, when the steering wheel is vibrated by the vibration device, a relatively small torque (torque that varies periodically) is generated in the steering wheel due to the vibration. Therefore, as shown in Fig. 5, when the steering wheel is vibrated, the peak value (maximum value) of the steering torque TR acting on the steering wheel exceeds the threshold value TRth, and there is a possibility that the steering assistance cannot be temporarily (intermittently) performed. Therefore, the practicality of the conventional device is low.

[0008] An object of the present invention is to provide a lane departure prevention device with improved practicality.

[0009] In order to achieve the above object, the lane departure prevention device (1) of the present invention comprises: A vibration device (21) for vibrating the steering wheel; A steering shaft connected to the steering wheel. a drive device (24) that drives the steering mechanism to change the steering angle; Torque acting on the steering wheel a torque (TR) obtained by combining a torque applied to the steering wheel by a driver of the vehicle and a torque acting on the steering wheel by vibrating the steering wheel by the vibration device; A torque sensor (23) for detecting the torque A control device that, when it is detected that the host vehicle deviates from the center of the lane to an end side by a predetermined distance or more in a cross direction of the lane, executes a lane departure warning by activating the vibration device, and a steering assistance that controls the drive device so that the host vehicle does not deviate from the lane, and when the detected torque is equal to or greater than a predetermined value, executes the steering assistance. Prohibiteda control device (20) configured to stop Equipped with. The control device includes: When the lane departure warning is not being executed, the detected torque is equal to or greater than a predetermined first torque (T1). Before Prohibit steering assistance, When the lane departure warning is being executed, the detected torque is equal to or greater than a second torque (T2) that is greater than the first torque. Before Prohibit steering assistance, It is structured as follows.

[0010] As described above, in the lane departure prevention device according to the present invention, when the steering torque is equal to or greater than a threshold value, or equal to or greater than a predetermined value (threshold value), the steering assist mode is degraded or the steering assist is prohibited. The threshold value when the steering wheel is vibrating is increased compared to the threshold value when the steering wheel is not vibrated. This makes it possible to prevent the steering assist from being unintentionally degraded or prohibited due to the vibration of the steering wheel by the vibration device. Therefore, the lane departure prevention device according to the present invention has high practicality compared to conventional devices. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram of a lane departure prevention device according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view showing an example of position information. [Diagram 3] FIG. 3 is a flow chart of the override program. [Figure 4] FIG. 4 is a timing chart showing the timing of execution of the lane departure warning and steering assistance by the vehicle departure prevention device shown in FIG. [Diagram 5] FIG. 5 is a timing chart showing the execution timing of lane departure warning and steering assistance in a conventional device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (Summary) 1, a lane departure prevention device 1 according to one embodiment of the present invention is mounted on a vehicle V. As will be described in detail later, the lane departure prevention device 1 executes a "lane departure warning" that notifies the driver that the vehicle V may depart from its lane, and a "steering assist" that controls a steering device (a steering motor 24 described later) so that the vehicle V does not depart from its lane.

[0013] (Specific configuration) The lane departure prevention device 1 includes a periphery recognition system 10. The periphery recognition system 10 includes a camera device 11.

[0014] The camera device 11 is disposed on the upper part of the front windshield glass. The camera device 11 captures an image of the view in front of the vehicle V. The camera device 11 then analyzes the image (image data) (for example, using a well-known pattern recognition technique) to recognize a dividing line (white line) that divides the lane in which the vehicle V is traveling, and recognizes the position of the vehicle V in the cross direction of the lane (obtains position information). The position information includes, for example, as shown in FIG. 2, a distance DR between the right end of the front end face of the vehicle V and the right dividing line, and a distance DL between the left end of the front end face of the vehicle V and the left dividing line. This position information is supplied to a driving assistance ECU 40, which will be described later.

[0015] 1 again, the lane departure prevention system 1 further includes a steering device 20. The steering device 20 includes a vibration device 21, a steering angle sensor 22, a steering torque sensor 23, and a steering motor 24.

[0016] The vibration device 21 is built into, for example, the spokes of a steering wheel. The vibration device 21 includes a weight and an electric motor (not shown). A rotational axis (eccentric shaft) is provided at a position away from the center of gravity of the weight. This rotational axis is connected to the output shaft of the electric motor. The weight rotates when power is supplied to the electric motor. The rotation of the weight generates a centrifugal force in the weight. As the rotational axis of the weight is offset from the center of gravity, vibrations are generated in the vibration device 21. This vibration is transmitted to the steering wheel, causing the steering wheel to vibrate.

[0017] The steering angle sensor 22 detects the steering angle (also called the steering angle or the turning angle) θ of the vehicle V. The steering torque sensor 23 detects the steering torque TR acting on the steering wheel.

[0018] The steering motor 24 drives a "steering mechanism including a steering shaft connected to a steering wheel and a steering gear mechanism (neither of which is shown)" to steer the left and right wheels. In other words, the steering motor 24 can change the steering angle of the vehicle V.

[0019] Furthermore, the lane departure prevention device 1 includes a steering ECU 30 and a driving assistance ECU (hereinafter referred to as "DSECU") 40. These ECUs are connected to each other via a controller area network (CAN) (not shown) so as to be capable of data exchange (communication).

[0020] ECU is an abbreviation for Electronic Control Unit, and is an electronic control circuit whose main components are a microcomputer including a CPU, ROM (flash ROM), RAM, and interfaces. The CPU realizes various functions by executing instructions (routines) stored in the ROM (flash ROM). Note that the functions of multiple types of ECUs may be realized by one ECU (integrated ECU).

[0021] The steering ECU 30 controls the steering device. The steering angle sensor 22 and the steering torque sensor 23 are connected to the steering ECU 30. The steering ECU 30 receives detection signals from these sensors.

[0022] The DSECU 40 acquires position information from the camera device 11. As described later, the DSECU 40 executes a lane departure warning based on the information. Furthermore, the DSECU 40 acquires steering information (steering angle θ and steering torque TR) from the steering angle sensor 22 and the steering torque sensor 23 via the steering ECU 30. Based on the information, the DSECU 40 controls the steering motor 24 via the steering ECU to execute steering assistance. The DSECU 40 may acquire map information including information on the current location of the vehicle V, the destination, and the shape of the road on which the vehicle V is traveling from a navigation system (not shown), and execute the lane departure warning and steering assistance based on the map information in addition to the above position information. In this specification, the functions of the DSECU 40 will be mainly described with reference to the parts related to the lane departure warning and steering assistance, but the DSECU 40 may further include a function of controlling an engine, a brake, and the like.

[0023] In addition, the lane departure prevention device 1 includes an operation switch 50. The operation switch 50 includes a switch operator (for example, a push button type switch operator) for the driver to specify whether or not "lane departure warning and steering assistance" is required.

[0024] (Activation) When the operation switch 50 is in the ON state, the DSECU 40 is in a state in which it can execute lane departure warning and steering assistance. That is, in this case, the DSECU 40 executes lane departure warning and steering assistance when a predetermined condition is satisfied. On the other hand, when the operation switch 50 is in the OFF state, the DSECU 40 does not execute lane departure warning and steering assistance.

[0025] (Lane Departure Warning) When the smaller distance D of the distance DL and the distance DR acquired from the camera device 11 is equal to or smaller than a predetermined threshold Dth (when the vehicle deviates from the center toward the end of the lane by a predetermined distance or more), the DSECU 40 differentially controls the vibration device 21 to vibrate the steering wheel. That is, the DSECU 40 supplies power to the electric motor of the vibration device 21 from a battery (not shown).

[0026] (Steering Assistance) The DSECU 40 determines a target driving line Ld (the center position between the right and left white lines of the lane on which the vehicle V is traveling) based on image data acquired from the camera device 11 (see FIG. 2). Next, the DSECU 40 determines a target steering angle for positioning the front end center position CL of the vehicle V on the target driving line Ld. Next, the DSECU 40 transmits a signal (steering command) representing the target steering angle to the steering ECU 30. The steering ECU 30 drives the steering motor 24 so that the current steering angle θ of the vehicle V coincides with the target steering angle.

[0027] (Override processing) The DSECU 40 does not execute steering assistance when the steering torque TR acquired from the steering torque sensor 23 is equal to or greater than a predetermined threshold TRth. Here, the DSECU 40 sets the threshold TRth as follows.

[0028] When the lane departure warning is not being executed (the steering wheel is not vibrated), the DSECU 40 sets the threshold TRth to a predetermined first torque T1. On the other hand, when the lane departure warning is being executed (the steering wheel is vibrated), the DSECU 40 sets the threshold TRth to a second torque T2 obtained by adding a predetermined value ΔT to the first torque T1. Here, the predetermined value ΔT is slightly larger than ½ of the amplitude of the fluctuating torque acting on the steering wheel when the steering wheel is vibrated using the vibration device 21.

[0029] The above-mentioned override process will be described more specifically with reference to Fig. 3. When the operation switch 50 is set to the on state, the DSECU 40 periodically (cycles) executes the override program shown in Fig. 3.

[0030] The DSECU 40 starts the override process from step 300. Next, in step 301, the DSECU 40 determines whether or not a lane departure warning is being executed. If a lane departure return is not being executed (step 301; No), the DSECU 40 sets the threshold value TRth to the first torque T1 in step 302. Next, in step 303, the DSECU 40 acquires the steering torque TR from the steering torque sensor 23. Next, in step 304, the DSECU 40 determines whether or not the steering torque TR is equal to or greater than the threshold value TRth. If the steering torque TR is smaller than the threshold value TRth (step 304: No), the DSECU 40 ends the override process in step 305. In this case, the DSECU 40 is in a state in which steering assistance can be executed. On the other hand, in step 304, if the steering torque TR is equal to or greater than the threshold value TRth (step 304: Yes), the DSECU 40 prohibits the execution of steering assistance in step 306. In this case, the DSECU 40 is in a state in which steering assistance cannot be performed. That is, even if the front end center position CL deviates from the target driving line Ld, the DSECU 40 does not perform steering assistance (control of the steering motor M).

[0031] In step 301, if lane departure return is being executed (step 301; Yes), the DSECU 40 sets the threshold value TRth to the second torque T2 in step 307 and proceeds to step 303.

[0032] With reference to FIG. 4, the operation of the DSECU 40 in a scene where the vehicle V travels slightly closer to the left edge of the road will be described. In this example, the driver does not intend to change lanes, but intends to proceed along the lane. In FIG. 4(A), the distance DL is greater than the threshold value Dth. Therefore, at this point, the DSECU 40 does not execute a lane departure warning. Therefore, the threshold value TRth is the first torque T1. At this point, the driver has started to operate the steering wheel, and a torque is acting on the steering wheel, but the value (steering torque TR) is equal to or less than the first torque T1. The DSECU 40 executes steering assistance (is in an executable state).

[0033] When the vehicle V advances from the state shown in FIG. 1A and the distance DL exceeds the threshold value Dth as shown in FIG. 1B, the DSECU 40 executes a lane departure warning. Therefore, the threshold value TRth is the second torque T2. At this point, the steering torque TR has increased from the point in time shown in FIG. 1A and is equivalent to the first torque T1 (a value slightly smaller than the first torque T1). Furthermore, since the steering wheel is vibrated by the vibration device 21, the peak value of the steering torque TR exceeds the first torque T1 but does not exceed the threshold value TRth (i.e., the second torque T2). Therefore, the DSECU 40 executes steering assistance (is in an executable state).

[0034] When the vehicle V advances from the state shown in FIG. 1B and the distance DL becomes greater than the threshold value Dth as shown in FIG. 1C, the DSECU 40 stops the lane departure warning. Therefore, the threshold value TRth returns to the first torque T1. At this point, the steering torque TR is smaller than the first torque T1. Therefore, the DSECU 40 executes steering assistance (is in an executable state).

[0035] (effect) As described above, the lane departure prevention device 1 according to the present embodiment can prevent steering assistance from being unintentionally not performed due to the vibration of the steering wheel caused by the vibration device 21. Therefore, the lane departure prevention device 1 has a higher practicality than the conventional devices.

[0036] The present invention is not limited to the above-described embodiment, and various modifications can be adopted within the scope of the present invention, as described below.

[0037] (Variation 1) In the above embodiment, when the steering torque TR is equal to or greater than the threshold value TRth, the DSECU 40 prohibits the steering assist. However, instead of this, the steering assist mode may be degraded. For example, the DSECU 40 may reduce the maximum value of the torque of the steering shaft generated by the steering motor 24.

[0038] (Variation 2) The threshold value TRth may be held at the second torque T2 until a predetermined time Δt has elapsed since the lane departure warning was terminated, and at that time the threshold value TRth may be returned from the second torque T2 to the first torque T1. In this case, the predetermined time Δt may be changed (specified) by the driver. For example, the predetermined time Δt may be set using a mobile information terminal connected to the DSECU 40.

[0039] (Variation 3) The driver may be able to change (specify) the strength of the vibration acting on the steering wheel by changing the rotation speed of the electric motor of the vibration device 21. In this case, the magnitude of the second torque T2 may be automatically set according to a set value SWV of the strength of the vibration of the steering wheel. In other words, it is preferable that the second torque T2 is configured to increase as the set value SWV increases.

[0040] By changing the manner of power supply to the electric motor of the vibration device 21, the driver may be able to change (specify) the manner (vibration pattern) of vibration acting on the steering wheel.

[0041] (others) The DSECU 40 may be configured not to determine whether the steering torque TR exceeds the threshold value TRth (steering torque determination) when the lane departure warning is being executed. In this case, the threshold value TRth may be always set to the first torque. In this case, the steering torque determination may be prohibited until a predetermined time Δt has elapsed since the lane departure warning was ended, and the steering torque determination may be resumed at that time. Also, instead of vibrating the steering wheel using the vibration device 21, the steering wheel may be vibrated by alternately rotating the steering wheel in a small angle in a clockwise direction and a counterclockwise direction using the steering motor 24. [Explanation of symbols]

[0042] 1... lane departure prevention device, 10... surrounding recognition system, 11... camera device, 20... steering device, 21... vibration device, 23... steering torque sensor, 24... steering motor, 40... driving assistance ECU, 50... operation switch, TR... steering torque

Claims

[Claim 1] A vibration device that vibrates the steering wheel; a drive device that drives a steering mechanism including a steering shaft connected to the steering wheel to change a steering angle; a torque sensor that detects a torque acting on the steering wheel, the torque being a composite torque of a torque applied to the steering wheel by a driver of the vehicle and a torque acting on the steering wheel as a result of the steering wheel being vibrated by the vibration device; a control device that, when it is detected that the host vehicle deviates from the center of the lane toward an end side by a predetermined distance or more, executes a lane departure warning by activating the vibration device, and executes steering assistance by controlling the drive device so that the host vehicle does not deviate from the lane, and is configured to prohibit the steering assistance when the detected torque is equal to or greater than a predetermined value; A lane departure prevention device comprising: The control device includes: prohibiting the steering assist when the detected torque is equal to or greater than a predetermined first torque in a state in which the lane departure warning is not being executed; prohibiting the steering assist when the detected torque is equal to or greater than a second torque that is greater than the first torque in a state in which the lane departure warning is being executed; The lane departure prevention device is configured as follows.

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