Vehicle control device

Abstract

To provide a vehicle control device capable of controlling steering vibration without giving a sense of incongruity to a driver while making the steering vibration in a lane deviation alarm function function as an alarm.SOLUTION: The vehicle control device 10 includes the driver steering torque detection unit 21 configured to detect the driver steering torque, the lane marking detection unit 23 configured to detect the lane marking of the lane, the lane deviation prediction unit 25 configured to predict the lane deviation of the vehicle, and the control unit 27 configured to perform the lane deviation suppressing control for preventing the lane deviation by generating the steering assist torque for assisting the steering of the vehicle when the lane deviation is predicted, and to perform the lane deviation warning control for warning the driver by generating the steering vibration for vibrating the steering wheel when the lane deviation is about to occur while the lane deviation suppressing control is performed. The control unit 27 determines the start direction and the magnitude of the steering vibration based on the directions of the driver steering torque and the steering assist torque.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a vehicle control device. [Background technology]

[0002] A vehicle warning device that generates vibrations in the vehicle's steering wheel as a warning is known. The vehicle warning device includes a motor that generates torque applied to the vehicle's steering mechanism in conjunction with steering of the steering wheel, and a control device that controls the drive of the motor so that the steering wheel vibrates as a warning. When the vehicle is about to deviate from its roadway, the control device sets the starting direction of the steering wheel vibration to the same direction as the steering direction of the steering wheel. The function of warning the driver by generating steering vibrations that vibrate the steering wheel held by the driver to prevent the vehicle from deviating from the roadway, i.e., the lane, is called a lane departure warning function. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-70108 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional vehicle warning devices, when the driver applies steering torque to the steering wheel in a direction that unintentionally causes the vehicle to deviate from its lane due to, for example, dozing off or being distracted, the steering vibration in the lane departure warning function starts in the same direction as the lane departure direction, which gives the driver the illusion that the steering wheel is being turned further to cause the vehicle to deviate from its lane, creating a sense of discomfort.

[0005] In addition, there is a lane departure prevention function that generates a steering assist torque in a direction to change the direction of the vehicle to prevent the vehicle from deviating from the lane when the vehicle is about to deviate from the lane, thereby assisting the driver in returning the vehicle to the lane. When the lane departure prevention function and the lane departure warning function are activated simultaneously, the driver feels an uncomfortable sensation as if the steering assist torque of the lane departure prevention function is being turned up or down due to the steering vibration of the lane departure warning function.

[0006] Therefore, it is necessary to more appropriately control the steering vibration in the lane departure warning function so as not to cause discomfort to the driver while still achieving the warning function.

[0007] Therefore, an object of the present invention is to provide a vehicle control device that can control steering vibration so that it does not cause discomfort to the driver while still allowing steering vibration to function as a warning in a lane departure warning function. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, a vehicle control device according to an embodiment of the present invention comprises a driver steering torque detection unit that detects the driver steering torque applied to the steering wheel by the driver; a lane line detection unit that detects lane line detection units on both the left and right sides of the lane in which the vehicle is traveling; a lane departure prediction unit that predicts lane departure of the vehicle based on the detection results of the lane line detection unit; and a control unit that, when lane departure is predicted by the lane departure prediction unit, performs lane departure prevention control to prevent lane departure by generating a steering assist torque to assist in steering the vehicle, and performs lane departure warning control to alert the driver by generating steering vibrations that vibrate the steering wheel if lane departure is imminent while the lane departure prevention control is being performed, and the control unit determines the direction in which the steering vibrations are to be started and the magnitude of the steering vibrations based on the driver steering torque and the direction of the steering assist torque. [Effects of the Invention]

[0009] The present invention provides a vehicle control device that is capable of controlling steering vibration so that the driver does not feel uncomfortable, while still allowing steering vibration to function as a warning in a lane departure warning function. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing an example of the configuration of a vehicle control system including a vehicle control device according to an embodiment of the present invention. [Figure 2] 3 is a timing chart showing the behavior of a vehicle in a time series in a situation where lane departure is predicted in a vehicle equipped with a vehicle control system including a vehicle control device according to an embodiment of the present invention. [Figure 3] 4 is a diagram showing an example of a relationship between a lane departure prevention torque and a lane departure prevention torque sensitive gain in the vehicle control device according to the embodiment of the present invention; FIG. [Figure 4] 3 is a flowchart showing the overall flow of lane departure warning control by a vehicle control device according to an embodiment of the present invention. [Figure 5] 4 is a flowchart showing the processing contents of steering vibration processing in lane departure warning control by the vehicle control device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The vehicle control device according to this embodiment will be described with reference to FIGS. 1 to 5. FIG.

[0012] FIG. 1 is a schematic diagram showing an example of the configuration of a vehicle control system including a vehicle control device according to an embodiment of the present invention.

[0013] The vehicle control device 10 shown in FIG. 1 assists the driver in driving by activating a lane departure prevention function and a lane departure warning function in a timely manner so that a vehicle equipped with a vehicle control system 100 including the vehicle control device 10 can prevent the vehicle from deviating from its lane.

[0014] The lane departure warning function issues a tactile warning (vibration warning) by vibrating the steering wheel of the vehicle when the vehicle is about to deviate from its lane. The warning issued by the lane departure warning function may include not only a tactile warning by vibration of the steering wheel, but also at least one of a visual warning (optical warning) by displaying on a display and an auditory warning (sound warning) by sounding an alarm.

[0015] The lane departure prevention function is a function that assists the driver in returning the vehicle to the lane by generating a steering assist torque in the direction of changing the direction of the vehicle when the vehicle is about to deviate from its lane.

[0016] Furthermore, the vehicle control system 100 is applicable not only to engine vehicles but also to electric vehicles, hybrid vehicles, fuel cell vehicles, and the like.

[0017] Hereinafter, the vehicle control device 10 and the vehicle control system 100 including the vehicle control device 10 will be described in detail with reference to FIG.

[0018] The vehicle control system 100 includes a torque sensor 1, a camera 3, a steering actuator 5, a human machine interface (HMI) device 7, and a vehicle control device 10. The torque sensor 1, the camera 3, the steering actuator 5, the HMI device 7, and the vehicle control device 10 are connected to each other so as to be able to communicate with each other via an in-vehicle network 11. The in-vehicle network 11 is, for example, a bus-type network that uses a CAN (Controller Area Network) as a communication protocol.

[0019] The torque sensor 1 detects a driver steering torque, which is a torque applied to the steering wheel by the driver. A detection signal of the torque sensor 1 is output to the vehicle control device 10.

[0020] The camera 3 is a photographing device that photographs an image ahead of the vehicle. The camera 3 has a solid-state image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), and photographs a predetermined photographing area at a predetermined frame rate. The image data photographed by the camera 3 is output to the vehicle control device 10. The image data photographed by the camera 3 includes road markings as well as dividing lines such as a roadway center line and roadway edge lines. The roadway center line is displayed, for example, as a white dotted line in the center of the road, and the roadway edge line is displayed, for example, as a white line on the outer edge of the road to indicate the boundary between the road and the shoulder. The camera 3 is attached to the windshield, the back of the rearview mirror, the front of the vehicle, or the like to photograph the area ahead.

[0021] The steering actuator 5 is a power source for the electric power steering device. The steering actuator 5 is, for example, an electric motor, and is provided on a path that transmits steering torque from a steering wheel provided at the driver's seat to a steering shaft, generating a steering assist torque that assists the driver in operating the steering wheel. The steering actuator 5, for example, applies a force to a rack-and-pinion mechanism of the vehicle's steering to change the direction of the vehicle's steered wheels, in other words, the turning angle of the steered wheels. The turning angle is the angle between a plane of rotation perpendicular to the rotation center line of the steered wheels and the longitudinal direction of the vehicle. Furthermore, the vehicle control system 100 according to this embodiment is not limited to rack-and-pinion steering systems, and can also be applied to other systems, such as circulating ball steering systems.

[0022] The HMI device 7 is an alarm device that presents various information to the vehicle occupants. The HMI device 7 accepts input operations by the occupants. The HMI device 7 includes a display, a speaker, a buzzer, a touch panel, switches, keys, etc. The HMI device 7 may be configured to issue at least one of a visual alarm and an audible alarm in the lane departure warning function in response to a control signal output from the vehicle control device 10.

[0023] The vehicle control device 10 is configured as a computer equipped with a central processing unit (CPU), an input / output interface, and storage devices such as ROM and RAM. Upon receiving the detection signal from the torque sensor 1 and the image data from the camera 3, the vehicle control device 10 executes predetermined calculations related to the control of the steering actuator 5 and the HMI device 7, and outputs control signals to the steering actuator 5 and the HMI device 7 according to the results of the calculations.

[0024] The vehicle control device 10 includes, for example, a driver steering torque detection unit 21 that detects driver steering torque, a lane marking detection unit 23 that detects markings on both the left and right sides of the lane in which the vehicle is traveling, a lane departure prediction unit 25 that predicts lane departure, which is the deviation of the vehicle from its lane, based on the detection results of the lane marking detection unit 23, and a control unit 27 for controlling the steering actuator 5 and the HMI device 7.

[0025] The driver steering torque detection unit 21 detects the driver steering torque applied to the steering wheel by the driver. The detection of the driver steering torque by the driver steering torque detection unit 21 is based on the output signal of the torque sensor 1.

[0026] The lane marking detection unit 23 performs preprocessing, such as image processing and / or coordinate transformation, on the image data output from the camera 3, and detects the lane markings on both the left and right sides of the lane in which the vehicle is traveling by edge detection and binarization. Furthermore, the lane marking detection unit 23 identifies the lane center, which is the center position of the lane, based on the positions of the detected lane markings on both the left and right sides.

[0027] The lane departure prediction unit 25 estimates lane departure of the vehicle from the positional relationship between the lane marking and the vehicle based on the detection result of the lane marking detection unit 23. For example, the lane departure prediction unit 25 determines whether the distance between the vehicle and the lane marking is equal to or less than a first approach distance, which is a preset distance. If the distance between the vehicle and the lane marking is equal to or less than the first approach distance, the lane departure prediction unit 25 determines that the vehicle will deviate from the lane within a short period of time and predicts lane departure. At this time, the lane departure prediction unit 25 changes a first request flag, which requests the generation of steering assist torque in response to lane departure, from OFF to ON. Furthermore, if the distance between the vehicle and the lane marking is equal to or less than a second approach distance, which is a predetermined distance shorter than the first approach distance, the lane departure prediction unit 25 changes a second request flag, which requests the issuance of a warning in response to lane departure, from OFF to ON. This second request flag is a trigger flag that changes to OFF relatively quickly after being turned ON. Furthermore, based on the detection results of the lane marking detection unit 23, the lane departure prediction unit 25 changes the first request flag from ON to OFF when the distance between the detected lane center position and the center position in the vehicle width direction becomes less than a predetermined distance and the vehicle becomes parallel to the lane.

[0028] When lane departure prediction unit 25 predicts that the vehicle will depart from its lane, control unit 27 performs lane departure prevention control to prevent the vehicle from deviating from its lane by generating a steering assist torque that assists in steering the vehicle. The lane departure prevention function described above is realized by lane departure prevention control performed by control unit 27. The steering assist torque in lane departure prevention control may be referred to as lane departure prevention torque hereinafter. The lane departure prevention torque is a torque that attempts to return the vehicle to the center of the lane when lane departure is predicted.

[0029] Specifically, when lane departure prediction unit 25 predicts lane departure of the vehicle and the first request flag changes from OFF to ON, control unit 27 outputs a command signal to steering actuator 5 to generate a lane departure prevention torque to prevent lane departure. Furthermore, when the first request flag changes from ON to OFF, control unit 27 stops outputting this command signal. Furthermore, control unit 27 pre-stores a lookup table that defines the relationship between the lane departure prevention torque and the distance between the vehicle and the left and right lane markings of the traveling lane calculated by lane departure prediction unit 25. Control unit 27 then refers to this table to obtain the lane departure prevention torque corresponding to the distance between the vehicle and the left and right lane markings of the traveling lane, which changes from moment to moment and is calculated by lane departure prediction unit 25, and outputs a command signal to steering actuator 5 to generate the obtained lane departure prevention torque.

[0030] The lane departure prevention control has a first control mode and a second control mode different from the first control mode. In the first control mode, when the vehicle approaches the lane and the approach distance is equal to or less than a first approach distance, the vehicle is controlled to return to the center of the lane. At this time, to return the vehicle to the center of the lane, a lane departure prevention torque is generated in a lane departure prevention direction, which is a direction to prevent the vehicle from leaving the lane. The lane departure prevention direction is a direction in which the steering wheel turns left when the vehicle approaches a dividing line on the right side of the traveling lane, and a direction in which the steering wheel turns right when the vehicle approaches a dividing line on the left side of the traveling lane. Furthermore, in the second control mode, after the first control mode, i.e., after the vehicle has avoided lane departure, the vehicle is controlled to move toward the center of the lane. At this time, in order to smoothly return the vehicle to the center of the lane, a lane departure prevention torque is generated in the lane departure direction, which is the opposite direction to the direction to prevent the vehicle from leaving the lane. The lane departure direction is the direction in which the steering wheel is turned to the right when the vehicle moves from the right-hand dividing line of the lane to the center of the lane, and the direction in which the steering wheel is turned to the left when the vehicle moves from the left-hand dividing line of the lane to the center of the lane. Furthermore, the lane departure suppression torque is defined as a positive value for torque that turns the steering wheel to the left and a negative value for torque that turns the steering wheel to the right.

[0031] Furthermore, if lane departure is imminent while lane departure suppression control is being performed, the control unit 27 performs lane departure warning control, which issues a warning to the driver about lane departure by generating steering vibrations that vibrate the steering wheel. The lane departure warning function described above is realized by the lane departure warning control performed by the control unit 27. In the following description, unless otherwise specified, steering vibration refers to steering vibration in lane departure warning control.

[0032] Specifically, when the vehicle is about to depart from the lane while lane departure prevention control is being performed, that is, when the distance between the vehicle and the lane marking becomes equal to or shorter than the second approach distance and the second request flag changes from OFF to ON, the control unit 27 outputs a command signal to the steering actuator 5 to generate steering vibrations that vibrate the steering wheel for a predetermined period of time. At this time, the steering actuator 5 applies the steering vibrations to the steering wheel so as to be superimposed on the lane departure prevention torque. For example, when the steering actuator 5 is an electric motor, the control unit 27 applies vibrations to the steering wheel by outputting a command signal to the steering actuator 5 to periodically switch the direction of rotation. Furthermore, when the control unit 27 determines that an alarm should be sounded, for example, the control unit 27 may output a command signal to the HMI device 7 to generate a predetermined alarm sound from a speaker or buzzer provided in the HMI device 7. Note that, among the lane departure prevention control performed by the control unit 27, control when the type of alarm is steering vibration may be referred to as steering vibration control hereinafter.

[0033] FIG. 2 is a timing chart showing the behavior of a vehicle in a time series in a situation where lane departure is predicted in a vehicle equipped with a vehicle control system including a vehicle control device according to an embodiment of the present invention.

[0034] Here, with reference to FIG. 2, the lane departure suppression control and lane departure warning control performed by the control unit 27 in a situation where lane departure is predicted will be further described.

[0035] In FIG. 2 , the vehicle V is traveling on a lane DL having a right-side marking RDL and a left-side marking LDL, and is gradually approaching the right-side marking RDL and is in a situation where it is about to deviate from the right-side marking RDL. In this embodiment, the lane departure prevention torque sensing gain is a variable having a positive value that is set according to the lane departure prevention torque, and may be multiplied by a predetermined constant and used to calculate the amplitude of steering vibration. In other words, the lane departure prevention torque sensing gain may be used as a variable for adjusting the amplitude of steering vibration. In this case, the time change of the lane departure prevention torque sensing gain relatively represents the time change of the amplitude of steering vibration while the steering vibration is being implemented. Note that the time changes of the first request flag, the second request flag, the lane departure prevention torque, and the lane departure prevention torque sensing gain shown in FIG. 2 are merely examples to facilitate understanding of the following description.

[0036] As shown in FIG. 2 , at time t0, when the vehicle V approaches the lane marking RDL and the distance between the vehicle V and the lane marking RDL becomes equal to or less than the first approach distance, the first request flag is changed from OFF to ON to perform lane departure prevention control. When the first request flag is changed to ON, a lane departure prevention torque is generated in the lane departure prevention direction as the vehicle V approaches the lane marking RDL, changing the vehicle V's travel trajectory TR. Between time t0 and time t1, approximately at the time when the magnitude of the lane departure prevention torque is at its maximum, the distance between the vehicle V and the lane marking RDL becomes equal to or less than the second approach distance, and the second request flag, which serves as a trigger flag for performing lane departure warning control, is changed from OFF to ON, and steering vibration is initiated. At this time, the lane departure prevention torque sensitive gain is at its minimum. Once steering vibration is initiated, it continues to be generated for a predetermined period of time. The predetermined period of time may be set to end the steering vibration at any time between time t1 and time t4 or at any time after time t4. The steering vibration may be ended, for example, at the time when the first request flag changes from ON to OFF, that is, at the time when the lane departure prevention control ends. In the example of Fig. 2, by setting the end time of the steering vibration to time t4, the lane departure prevention control and the lane departure warning control end simultaneously.

[0037] Next, from time t1 to time t2, when the traveling direction of vehicle V changes from right to left, the magnitude of the lane departure prevention torque generated in the lane departure prevention direction decreases. Next, from time t2 to time t3, as vehicle V approaches the lane center CL, the magnitude of the lane departure prevention torque generated in the lane departure direction increases, causing vehicle V to change its traveling direction from left to right. At this time, the lane departure prevention torque sensitive gain is at its maximum. Next, from time t3 to time t4, when the traveling direction of vehicle V changes, the lane departure prevention torque in the lane departure direction decreases. Then, at time t4, when the traveling direction of vehicle V becomes parallel to the lane, the first request flag changes from ON to OFF, and the generation of the lane departure prevention torque stops. In other words, lane departure prevention control ends.

[0038] As described above, in conventional vehicle warning devices, when the driver is dozing or looking away from the wheel and unintentionally applies steering torque to the steering wheel in the direction of lane departure, the steering vibration starts in the direction of lane departure. Therefore, the driver may feel a sense of discomfort as if the steering wheel is being turned further to cause the vehicle to depart from the lane due to the steering vibration. Furthermore, when the lane departure prevention function and the lane departure warning function are activated simultaneously, the driver may feel a sense of discomfort as if the lane departure prevention torque is being turned further or returned due to the steering vibration.

[0039] Therefore, the control unit 27 determines the direction in which to start steering vibration and the magnitude of steering vibration based on the driver steering torque and the direction of the steering assist torque in the lane departure prevention control, that is, the direction of the lane departure prevention torque.

[0040] Specifically, the control unit 27 estimates the driver's intention and the driving state of the driver based on the magnitude of the driver's steering torque acquired by the driver steering torque detection unit 21. The control unit 27 then generates steering vibration by efficiently setting the start direction and magnitude of the steering vibration according to these estimation results and the direction of the lane departure prevention torque, thereby making it easier for the driver to notice the steering vibration and providing the driver with a sense of security, i.e., lane departure warning control. Furthermore, when the lane departure prevention torque is being generated, the control unit 27 can distinguish between a case where the vehicle is intentionally approaching a lane marking, for example, to change lanes, and a case where the vehicle is unintentionally approaching a lane marking, and generate steering vibration according to each case.

[0041] Hereinafter, the direction in which steering vibration starts may be referred to as the steering vibration start direction or simply as the vibration start direction. The magnitude of steering vibration refers to the amplitude of the steering vibration. The amplitude of the steering vibration is, for example, a value within a range of 0.2 G to 0.4 G. In this embodiment, the driver's intention and driving state are estimated based on the magnitude of the driver's steering torque. However, the means for estimating the driver's intention and driving state are not limited to this. For example, at least one of the operation status of the turn signal (i.e., the output of the turn signal switch) and the results of monitoring the driver's driving state by a driver monitor (e.g., an in-vehicle camera) (not shown) further provided in the vehicle control system 100 may be further used to estimate the driver's intention and driving state.

[0042] In addition, when the vehicle's lane departure is not based on the driver's intention, the control unit 27 may start steering vibration in the same direction as the direction of the steering assist torque in the lane departure prevention control, i.e., the same direction as the direction of the lane departure prevention torque.

[0043] If the lane departure is unintentional and steering vibration is initiated in the opposite direction to the direction of lane departure prevention torque application, the steering wheel may begin to move in the direction that causes the vehicle to deviate from the lane, which may frighten the driver. The control unit 27 determines whether the vehicle is approaching a lane marking, i.e., whether the driver intends the vehicle to depart from the lane, based on the magnitude of the driver's steering torque. For example, if the magnitude of the driver's steering torque is equal to or less than a predetermined value, the control unit 27 determines that the lane departure is unintentional, i.e., not based on the driver's intention. This predetermined value is equal to or greater than the magnitude of the hands-on determination steering torque that determines that the driver is gripping or operating the steering wheel, but is equal to or less than the magnitude of the cancel torque that causes the vehicle control device 10 to stop steering intervention by the lane departure prevention control. If the control unit 27 determines that the lane departure is unintentional, it generates steering vibration in the same direction as the direction of application of the lane departure prevention torque that prevents the vehicle from deviating from the lane. Therefore, when lane departure is not based on the driver's intention, the control unit 27 avoids starting steering vibration in the direction opposite to the direction in which the lane departure suppression torque is applied, thereby eliminating the driver's fear that the steering wheel will unintentionally start moving in a direction that will take the vehicle out of the lane.

[0044] Furthermore, when the lane departure of the vehicle is based on the driver's intention, the control unit 27 may start steering vibration in the same direction as the direction of the driver's steering torque. When the control unit 27 determines, based on the magnitude of the driver's steering torque, that the vehicle is approaching a lane marking due to an intended or intentional operation by the driver, the control unit 27 matches the direction of the steering vibration start with the direction of the driver's steering torque, thereby suppressing the sense of incongruity and discomfort that the steering vibration causes to the driver.

[0045] Furthermore, when the lane departure of the vehicle is based on the driver's intention, the control unit 27 may start steering vibration in the direction opposite to the direction of the steering assist torque in the lane departure prevention control, i.e., the direction of the lane departure prevention torque. For example, when the driver attempts to change lanes, the driver's intentional steering wheel operation causes the vehicle to approach a marking line. In this case, as the vehicle approaches the marking line, the lane departure prevention control is implemented, and the lane departure prevention torque is generated in a direction that moves the vehicle away from the marking line, i.e., in the lane departure prevention direction. When the control unit 27 determines, based on the magnitude of the driver's steering torque, that the steering wheel operation is intended by the driver, it starts steering vibration in the lane departure direction, which is the opposite direction to the lane departure prevention direction. In other words, when the control unit 27 determines that the lane departure of the vehicle is based on the driver's intention, it sets the start direction of steering vibration to the lane departure direction. In this way, the control unit 27 suppresses the sense of incongruity and discomfort that the steering vibration causes to the driver.

[0046] Furthermore, the control unit 27 may determine that the lane departure of the vehicle is not based on the driver's intention when the magnitude of the driver's steering torque is equal to or smaller than a predetermined value, and may determine that the lane departure of the vehicle is based on the driver's intention when the magnitude of the driver's steering torque exceeds the predetermined value. In this way, the control unit 27 can easily perform appropriate steering vibration control by assuming whether the lane departure is intentional or not based on the relationship between the magnitude of the driver's steering torque and the predetermined value.

[0047] In addition, the control unit 27 may reduce steering vibration when the lane departure prevention torque is generated in the same direction as the lane departure prevention direction, which is the direction that prevents the vehicle from leaving its lane, compared to when the lane departure prevention torque is generated in the same direction as the lane departure direction, which is the direction that causes the vehicle to deviate from its lane.

[0048] Specifically, referring again to FIG. 2, when lane departure of vehicle V is being prevented, that is, when the lane departure prevention control is in the first control mode, a large lane departure prevention torque is generated in the lane departure prevention direction between time t0 and time t1, and the driver's attention is directed toward the steering wheel. In particular, immediately after time t0 when lane departure control starts, the lane departure prevention torque changes significantly and the steering angle of the steering wheel also changes significantly, so the driver's attention is significantly directed toward the steering wheel. At this time, the driver is highly sensitive to the behavior of the steering wheel, that is, in a state where the driver reacts sensitively to the behavior of the steering wheel, and the steering vibration causes the driver to feel a greater sense of discomfort. Therefore, when the driver is in such a state, the control unit 27 reduces the steering vibration to reduce the sense of discomfort caused by the steering vibration.

[0049] On the other hand, in the second control mode of the lane departure prevention control that controls the vehicle V to travel parallel to the lane center CL and the lane DL, only a small lane departure prevention torque is generated in the lane departure direction between time t3 and time t4, so the driver's attention is taken away from the steering wheel. At this time, the driver is in a state where his / her sensitivity to the behavior of the steering wheel is low, and the discomfort caused by the steering vibration to the driver is reduced. Therefore, the control unit 27 increases the steering vibration when the driver is in such a state. Therefore, the control unit 27 can set the magnitude of the steering vibration to a value corresponding to the lane departure prevention torque, and increase the steering vibration when the driver is unlikely to feel discomfort from the steering vibration, and decrease the steering vibration when the driver is likely to feel discomfort.

[0050] Furthermore, when the lane departure prevention torque is generated in the same direction as the lane departure prevention direction, the control unit 27 may decrease the steering vibration as the magnitude of the lane departure prevention torque increases, and when the lane departure prevention torque is generated in the same direction as the lane departure direction, the control unit 27 may increase the steering vibration as the magnitude of the lane departure prevention torque increases. As a result, the steering vibration decreases in the first control mode of the lane departure prevention control in which the magnitude of the lane departure prevention torque increases, while the steering vibration increases in the second control mode of the lane departure prevention control in which the magnitude of the lane departure prevention torque decreases. In other words, the steering vibration increases when the driver is unlikely to feel uncomfortable with the steering vibration, and decreases when the driver is likely to feel uncomfortable. This makes it possible to implement lane departure warning control that provides a high warning effect without causing excessive discomfort to the driver. Furthermore, the smaller the steering vibration, the less it interferes with the driver's steering wheel operation, so when lane departure prevention control is performed without the driver's intention to depart from the lane, the vehicle can be controlled to move smoothly toward the center of the lane, making it possible to implement the lane departure prevention control and lane departure warning control that the driver expects.

[0051] Furthermore, the control unit 27 may minimize steering vibration when the lane departure is based on the driver's intention. When the driver is intentionally causing the vehicle to deviate from the lane, a warning using steering vibration is not substantially necessary unless there is an error in determining whether the lane departure is based on the driver's intention. Therefore, by minimizing steering vibration when the lane departure is based on the driver's intention, the control unit 27 reduces the discomfort felt by the driver due to the generation of unnecessary steering vibration.

[0052] Furthermore, when the magnitude of the driver's steering torque exceeds a predetermined value, the control unit 27 may determine that the lane departure is based on the driver's intention, and gradually reduce the steering vibration as the vehicle approaches the lane departure. If the magnitude of the driver's steering torque continues to be greater than the predetermined value, it becomes possible to estimate that the driver is more intentionally deviating from the lane. Furthermore, when the lane departure is based on the driver's intention, steering vibration is no longer necessary, and therefore, as the vehicle approaches the lane departure, the magnitude of the steering vibration is gradually reduced to reduce the driver's discomfort caused by the steering vibration.

[0053] Fig. 3 is a diagram showing an example of the relationship between the lane departure prevention torque and the lane departure prevention torque sensing gain in the vehicle control device according to the embodiment of the present invention. Note that Fig. 3 shows the relationship between the lane departure prevention torque and the lane departure prevention torque sensing gain in the lane departure prevention control that is performed when the vehicle is about to depart from the marking line on the right side of the lane in which the vehicle is traveling.

[0054] When lane departure is based on the driver's intention, the magnitude of steering vibration, which gradually decreases as the vehicle approaches lane departure, can be adjusted by the lane departure prevention torque sensing gain described above. For example, as shown in Fig. 3, the lane departure prevention torque sensing gain determined based on the hyperbolic tangent function expressed by the following relational expression (1) from the relationship between constant a, constant b, lane departure prevention torque x, and lane departure prevention torque sensing gain y may be used to adjust the amplitude of steering vibration. y=(-a)×tanh((b)×(x))+1 (1) In the example of FIG. 3, three curves L1 to L3 are shown in relational expression (1), where constant a is 0.3 or 0.5, constant b is 0, 5, or 0.75, and lane departure prevention torque x is in the range of -5 Nm to 5 Nm. Note that constant a is, for example, a value within the range of 0.1 to 4, and constant b is, for example, a value within the range of 0.1 to 0.9. Furthermore, when lane departure prevention torque x is greater than 0 Nm, it is generated in the direction of lane departure prevention, and when it is less than 0 Nm, it is generated in the direction of lane departure.

[0055] In the case of the above relational expression (1), when the vehicle attempts to depart from its lane, the lane departure prevention torque gradually increases and the lane departure prevention torque sensing gain gradually decreases as the vehicle approaches lane departure. Therefore, the magnitude of the steering vibration calculated by multiplying the lane departure prevention torque sensing gain by a predetermined constant gradually decreases as the lane departure prevention torque gradually increases as the vehicle approaches lane departure. Note that the magnitude of the steering vibration may be adjusted using not only the hyperbolic tangent function expressed by the above relational expression (1) but also the lane departure prevention torque sensing gain obtained based on a sigmoid function.

[0056] Here, the operation (mainly steering vibration control) of the vehicle control device 10 according to the present embodiment described above will be explained with reference to Figures 4 and 5. For ease of explanation, it is assumed that the lane departure prevention function and lane departure warning function are enabled, that is, the lane departure prevention control and lane departure warning control are executable. It is also assumed that the lane departure warning function is set to either steering vibration or alarm sounding as the type of warning.

[0057] 4, first, in step S1, the vehicle control device 10 reads various control information used for lane departure suppression control and lane departure warning control. The control information read in step S1 includes a driver steering torque and an image ahead of the vehicle including lane markings.

[0058] In step S2 following step S1, the vehicle control device 10 determines whether the second request flag is ON. Whether the second request flag is ON or not is based on the processing results of the lane departure prediction unit 25, which is not shown in Fig. 4 and whose description is omitted. If the second request flag is ON (YES in step S2), the process proceeds to step S3, and if the second request flag is not ON (NO in step S2), the current control is terminated.

[0059] In step S3 following YES in step S2, the vehicle control device 10 determines whether the type of alarm is steering vibration. If the type of alarm is steering vibration (YES in step S3), the process proceeds to step S4, and if the type of alarm is not steering vibration (NO in step S3), the process proceeds to step S5.

[0060] In step S4 following YES in step S3, the vehicle control device 10 performs steering vibration processing, which follows the procedure shown in the flowchart of FIG.

[0061] In step S5 following NO in step S3, the vehicle control device 10 carries out processing to sound an alarm. A description of the processing to sound an alarm will be omitted.

[0062] After executing the process of step S4 or step S5, the vehicle control device 10 ends the current control.

[0063] In the flowchart shown in FIG. 5, in step S11, the vehicle control device 10 sets the start direction of steering vibration to the direction of the driver's steering torque.

[0064] In step S12 following step S11, the vehicle control device 10 determines whether the first request flag is ON. Whether the first request flag is ON or not is based on the processing results of the lane departure prediction unit 25, which is not shown in Fig. 5 and whose description is omitted. If the first request flag is ON (YES in step S12), the process proceeds to step S13, and if the vehicle first request flag is not ON (NO in step S12), the process proceeds to step S16.

[0065] In step S13 following YES in step S12, the vehicle control device 10 determines whether the magnitude of the driver's steering torque is equal to or less than a predetermined value. If the magnitude of the driver's steering torque is equal to or less than the predetermined value (YES in S13), the process proceeds to step S14, and if the driver's steering torque is not equal to or less than the predetermined value (NO in S13), the process proceeds to step S16. If the magnitude of the driver's steering torque is equal to or less than the predetermined value, the vehicle control device 10 determines that the vehicle's lane departure is not based on the driver's intention, and if the magnitude of the driver's steering torque exceeds the predetermined value, the vehicle control device 10 determines that the vehicle's lane departure is based on the driver's intention.

[0066] In step S14 following YES in step S13, the vehicle control device 10 determines whether the direction of the driver's steering torque is equal to the direction of the lane departure prevention torque. If the direction of the driver's steering torque is equal to the direction of the lane departure prevention torque (YES in S14), the process proceeds to step S16, and if the direction of the driver's steering torque is not equal to the direction of the lane departure prevention torque (NO in S14), the process proceeds to step S15.

[0067] In step S15 following NO in step S14, the vehicle control device 10 reverses the starting direction of the steering vibration.

[0068] In step S16 following step S15 (NO in step S12, NO in step S13, YES in step S14), or step S16, the vehicle control device 10 calculates the magnitude of steering vibration based on the lane departure prevention torque sensing gain. That is, the vehicle control device 10 multiplies a predetermined constant by the lane departure prevention torque sensing gain to obtain the magnitude of steering vibration, i.e., the amplitude of steering vibration.

[0069] In step S17 following step S16, the vehicle control device 10 performs steering vibration based on the amplitude of the steering vibration obtained in the processing of step S16, that is, the magnitude of the steering vibration.

[0070] In step S18 following step S17, the vehicle control device 10 determines whether a predetermined time has elapsed since the start of steering vibration. If the predetermined time has elapsed since the start of steering vibration (YES in S18), the vehicle control device 10 ends the steering vibration. If the predetermined time has not elapsed since the start of steering vibration (NO in S18), the processes of steps S16 and S17 are repeated until the predetermined time has elapsed since the start of steering vibration.

[0071] As described above, the vehicle control device 10 according to this embodiment includes a control unit 27 that determines the start direction and magnitude of steering vibration based on the driver's steering torque and the direction of the lane departure prevention torque. The vehicle control device 10 estimates the driver's intention and driving state based on, for example, the magnitude of the driver's steering torque. The vehicle control device 10 then generates steering vibration by efficiently setting the magnitude and start direction of steering vibration based on these estimation results and the direction of the lane departure prevention torque. This allows the vehicle control device 10 to easily notice the steering vibration and perform lane departure warning control that gives the driver a sense of security. In other words, the vehicle control device 10 can fully utilize the steering vibration in the lane departure warning function as a warning. Furthermore, when the lane departure prevention torque is being generated, the vehicle control device 10 can distinguish between a case in which the vehicle is intentionally approaching a lane marking, for example, to change lanes, and a case in which the vehicle is unintentionally approaching a lane marking, and generate steering vibration appropriate for each case. In other words, the vehicle control device 10 can control steering vibration in a way that does not cause discomfort to the driver.

[0072] Furthermore, the vehicle control device 10 according to this embodiment includes a control unit 27 that starts steering vibration in the same direction as the direction of the lane departure prevention torque when the lane departure is not based on the driver's intention. If steering vibration starts in the opposite direction to the direction in which the lane departure prevention torque is applied when the lane departure is not based on the driver's intention, the steering wheel may start to move in a direction that causes the vehicle to deviate from the lane, which may cause the driver to feel fear. Therefore, the vehicle control device 10 avoids starting steering vibration in the opposite direction to the direction in which the lane departure prevention torque is applied when the lane departure is not based on the driver's intention, thereby eliminating the driver's fear of the steering wheel starting to move unintentionally in a direction that causes the vehicle to deviate from the lane.

[0073] Furthermore, the vehicle control device 10 according to this embodiment includes a control unit 27 that starts steering vibration in the same direction as the direction of the driver's steering torque when the lane departure is based on the driver's intention. Therefore, when the vehicle control device 10 determines, based on the magnitude of the driver's steering torque, that the vehicle is approaching a lane marking due to an intended or intentional operation by the driver, it can reduce the sense of incongruity and discomfort that the steering vibration causes to the driver by aligning the steering vibration start direction with the direction of the driver's steering torque.

[0074] Furthermore, the vehicle control device 10 according to this embodiment is equipped with a vehicle control device that starts steering vibration in the direction opposite to the direction of the lane departure suppression torque when the lane departure is based on the driver's intention. Therefore, when the vehicle control device 10 determines that the lane departure of the vehicle is based on the driver's intention, it is possible to suppress the sense of incongruity and discomfort that the steering vibration causes to the driver by setting the start direction of the steering vibration to the lane departure direction.

[0075] Furthermore, the vehicle control device 10 according to this embodiment includes a control unit 27 that determines that the lane departure is not based on the driver's intention when the magnitude of the driver's steering torque is equal to or less than a predetermined value, and determines that the lane departure is based on the driver's intention when the magnitude of the driver's steering torque exceeds the predetermined value. Therefore, the vehicle control device 10 can easily implement an appropriate steering vibration that does not cause discomfort to the driver by estimating whether the lane departure is intentional or not based on the relationship between the magnitude of the driver's steering torque and the predetermined value.

[0076] Furthermore, the vehicle control device 10 according to this embodiment includes a control unit 27 that reduces steering vibration when the lane departure prevention torque is generated in the same direction as the lane departure prevention direction compared to when the lane departure prevention torque is generated in the same direction as the lane departure direction. Therefore, the vehicle control device 10 sets the magnitude of the steering vibration to a value corresponding to the lane departure prevention torque, and can increase the steering vibration when the driver is unlikely to feel uncomfortable with the steering vibration, and can reduce the steering vibration when the driver is likely to feel uncomfortable with the steering vibration.

[0077] Furthermore, the vehicle control device 10 according to this embodiment includes a control unit 27 that, when the lane departure prevention torque is generated in the same direction as the lane departure prevention direction, reduces steering vibration as the magnitude of the lane departure prevention torque increases, and, when the lane departure prevention torque is generated in the same direction as the lane departure direction, increases steering vibration as the magnitude of the lane departure prevention torque increases. Therefore, the steering vibration increases when the driver is unlikely to feel uncomfortable with the steering vibration, and decreases when the driver is likely to feel uncomfortable. This allows the vehicle control device 10 to implement lane departure warning control with a high warning effect without excessively discomforting the driver. Furthermore, because the smaller the steering vibration, the less it interferes with the driver's steering wheel operation, the vehicle control device 10 allows the vehicle to smoothly navigate toward the center of the lane when lane departure prevention control is performed without the driver's intention to depart from the lane, thereby achieving both the lane departure prevention control and lane departure warning control that the driver expects.

[0078] Furthermore, the vehicle control device 10 according to this embodiment includes a control unit 27 that minimizes steering vibration when lane departure is based on the driver's intention. Therefore, the vehicle control device 10 can reduce the discomfort felt by the driver due to substantially unnecessary steering vibration.

[0079] Furthermore, the vehicle control device 10 according to this embodiment includes a control unit 27 that determines that lane departure is based on the driver's intention when the magnitude of the driver's steering torque exceeds a predetermined value, and gradually reduces steering vibration as the vehicle approaches lane departure. Therefore, the vehicle control device 10 can estimate that the driver is more intentionally leaving the lane by maintaining a state in which the magnitude of the driver's steering torque exceeds the predetermined value. Furthermore, the vehicle control device 10 can reduce the discomfort the driver feels from steering vibration by gradually reducing the magnitude of steering vibration, which is unnecessary when lane departure is based on the driver's intention, as the vehicle approaches lane departure.

[0080] Therefore, the vehicle control device 10 according to this embodiment can control the steering vibration so that it does not feel strange to the driver, while still allowing the steering vibration in the lane departure warning function to function as a warning.

[0081] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0082] 1...torque sensor, 3...camera, 5...steering actuator, 7...human-machine interface device (HMI device), 10...vehicle control device, 11...in-vehicle network, 21...driver steering torque detection unit, 23...marking line detection unit, 25...lane departure prediction unit, 27...control unit, 100...vehicle control system.

Claims

1. a driver steering torque detection unit that detects a driver steering torque applied to a steering wheel by a driver; a lane marking detection unit that detects lane markings on both the left and right sides of a lane in which a vehicle is traveling; a lane departure prediction unit that predicts lane departure of the vehicle based on the detection result of the lane marking detection unit; a control unit that, when the lane departure prediction unit predicts the lane departure, performs lane departure prevention control to prevent the lane departure by generating a steering assist torque that assists steering of the vehicle, and, when the lane departure is about to occur while the lane departure prevention control is being performed, performs lane departure warning control to issue a warning to the driver by generating steering vibration that vibrates the steering wheel, The control unit determines the direction in which the steering vibration is to be started and the magnitude of the steering vibration based on the direction of the driver steering torque and the direction of the steering assist torque.

2. The vehicle control device according to claim 1 , wherein the control unit starts the steering vibration in the same direction as the direction of the steering assist torque when the lane departure is not based on the driver's intention.

3. The vehicle control device according to claim 2 , wherein the control unit starts the steering vibration in the same direction as the direction of the driver's steering torque when the lane departure is based on the driver's intention.

4. The vehicle control device according to claim 2 , wherein the control unit starts the steering vibration in a direction opposite to a direction of the steering assist torque when the lane departure is based on the driver's intention.

5. The control unit If the magnitude of the driver's steering torque is equal to or less than a predetermined value, it is determined that the lane departure is not based on the driver's intention, The vehicle control device according to claim 2 , wherein when the magnitude of the driver's steering torque exceeds a predetermined value, it is determined that the lane departure is based on the driver's intention.

6. 2. The vehicle control device according to claim 1, wherein the control unit reduces the steering vibration when the steering assist torque is generated in the same direction as a lane departure suppression direction, which is a direction that prevents the lane departure, compared to when the steering assist torque is generated in the same direction as a lane departure direction, which is a direction that causes the lane departure.

7. The control unit When the steering assist torque is generated in the same direction as the lane departure suppression direction, the steering vibration is reduced as the magnitude of the steering assist torque increases, 7. The vehicle control device according to claim 6, wherein, when the steering assist torque is generated in the same direction as the lane departure direction, the steering vibration increases as the magnitude of the steering assist torque increases.

8. The vehicle control device according to claim 7 , wherein the control unit minimizes the steering vibration when the lane departure is based on the driver's intention.

9. 8. The vehicle control device according to claim 7, wherein the control unit determines that the lane departure is based on the driver's intention when the magnitude of the driver's steering torque exceeds a predetermined value, and reduces the steering vibration as the lane departure approaches.

Images