Lane deviation determination device for vehicle and driving support device for vehicle

Abstract

To determine deviation of a vehicle from a lane at a more appropriate timing.SOLUTION: A lane deviation determination device for a vehicle V sets request output torque to a driving source of the vehicle V. The lane deviation determination device detects a vehicle speed to set a vehicle forward gazing point distance Dfgp on the basis of the vehicle speed, and corrects the forward gazing point distance Dfgp according to the request output torque to the driving source. Then, the lane deviation determination device predicts a lateral movement distance Dlat of the vehicle V at a position Pf located ahead of the vehicle V by the forward gazing point distance Dfgp, and determines deviation of the vehicle V from a traveling lane on the basis of the lateral movement distance Dlat.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a lane departure determination device for a vehicle and a driving assistance device for a vehicle. [Background technology]

[0002] There is a technology that sets a virtual gaze point (hereinafter referred to as "forward gaze point") in front of the vehicle and judges whether the vehicle is deviating from the lane it is traveling in based on the predicted lateral movement distance of the vehicle at the forward gaze point. Patent Document 1 does not judge whether the vehicle is deviating from the lane, but describes that the distance from the vehicle to the forward gaze point is calculated according to the vehicle speed, and the higher the vehicle speed, the longer this distance is, and the further away the forward gaze point is set. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-081123 A Summary of the Invention [Problem to be solved by the invention]

[0004] In this way, by setting the distance from the vehicle to the forward gaze point (hereinafter referred to as the "forward gaze point distance") according to the vehicle speed, it is possible to ensure the time necessary to respond by steering when there is a risk of deviation from the lane, but there is still room for improvement in the following areas:

[0005] In a situation where the vehicle accelerates or decelerates, the forward gaze point distance set according to the current vehicle speed is not a distance appropriate for the vehicle speed after acceleration or deceleration, making it difficult to judge lane departure at an appropriate time. Specifically, by using the current vehicle speed as the standard, the forward gaze point distance is short during acceleration, which tends to cause a delay in judgment, while the forward gaze point distance is long during deceleration, which tends to make the judgment unnecessarily early.

[0006] In view of the above circumstances, the present invention aims to provide a lane departure judgment device for a vehicle that can determine whether a vehicle has departed from a lane at a more appropriate timing, and a driving assistance device for a vehicle equipped with the same. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, a lane departure judgment device for a vehicle according to one embodiment of the present invention comprises a required output torque setting means for setting a required output torque for the vehicle's drive source, a vehicle speed detection means for detecting the vehicle speed, a forward gaze point distance setting means for setting a forward gaze point distance of the vehicle based on the vehicle speed detected by the vehicle speed detection means, a forward gaze point distance correction means for correcting the forward gaze point distance set by the forward gaze point distance setting means in accordance with the required output torque set by the required output torque setting means, a lateral movement distance prediction means for predicting the lateral movement distance of the vehicle at a position forward of the vehicle the forward gaze point distance corrected by the forward gaze point distance correction means, and a lane departure judgment means for determining whether the vehicle has deviated from the lane in which it is traveling based on the lateral movement distance predicted by the lateral movement distance prediction means.

[0008] A driving assistance device for a vehicle according to another aspect of the present invention includes a lane departure judgment device for the vehicle, and a control signal output means for outputting a control signal for departure from the lane when the lane departure judgment means judges that the vehicle has departed from the lane. Effect of the Invention

[0009] According to one aspect of the present invention, the forward gaze point distance set based on the vehicle speed is corrected according to the required output torque for the drive source, so that the forward gaze point distance can be set to be suitable for the vehicle speed after acceleration or deceleration due to a change in the required output torque, and it is possible to determine the departure of the vehicle from the lane at a more appropriate timing. This makes it possible to avoid a situation in which a delay in the determination causes a delay in steering response, or a situation in which the driver feels annoyed due to an unnecessarily early determination. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing a configuration of a vehicle driving assistance device according to an embodiment of the present invention; [Diagram 2] 2 is a schematic diagram showing an internal configuration of a controller (driving assistance controller) according to the above embodiment. FIG. [Diagram 3] 4 is a flowchart showing an overall flow of lane departure suppression control performed by a driving assistance controller. [Figure 4] 4 is a flowchart showing the contents of lane departure suppression processing in the above control. [Diagram 5] FIG. 11 is an explanatory diagram showing the relationship between a required torque change amount ΔTRQ and a torque correction value Htrq of the forward gaze point distance. [Figure 6] FIG. 2 is an explanatory diagram showing the relationship between the road inclination angle (road surface inclination angle) INC and the inclination angle correction value Hinc of the forward gaze point distance. [Figure 7] FIG. 2 is an explanatory diagram showing the operating principle of lane departure determination. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] FIG. 1 shows an overall configuration of a vehicle driving assistance device 1 according to one embodiment of the present invention.

[0013] In this embodiment, the vehicle has an internal combustion engine (hereinafter simply referred to as "engine") as its drive source, and travels by transmitting the output torque of the engine (hereinafter sometimes referred to as "engine torque") to wheels via a transmission. In this embodiment, the front wheels are drive wheels and the rear wheels are driven wheels. The drive source is not limited to the engine, and may be an electric motor or a combination of the engine and the electric motor.

[0014] The driving assistance device 1 according to this embodiment includes a controller (hereinafter, in order to distinguish it from other controllers, it is particularly referred to as a "driving assistance controller") 101. The driving assistance controller 101 is configured as an electronic control unit. The driving assistance device 1 further includes an accelerator opening sensor 201, a wheel speed sensor 202, a tilt angle sensor 203, an acceleration sensor 204, and other sensors capable of acquiring information used for driving assistance control, and also includes a camera for monitoring the front (hereinafter, it is referred to as a "forward camera") 301.

[0015] The driving assistance controller 101 is configured by a microcomputer equipped with a central processing unit (CPU), an input / output interface, and storage devices such as ROM and RAM. The driving assistance controller 101 constitutes the calculation unit of the driving assistance device 1, and receives output signals from various sensors that constitute the detection unit of the driving assistance device 1, such as an accelerator opening sensor 201. The driving assistance controller 101 then performs a predetermined calculation related to driving assistance control based on the output information of the sensors, and generates and outputs a command signal according to the result. Targets to which the command signal is output include the engine controller 401, the human machine interface (hereinafter abbreviated as "HMI") 501, and the steering controller 601.

[0016] The accelerator opening sensor 201 detects the accelerator operation amount APO by the driver. The accelerator operation amount APO is, for example, the amount of depression of the accelerator pedal by the driver. The accelerator operation amount APO indicates a required value of output torque for the engine (hereinafter referred to as "required engine torque"). The required engine torque corresponds to the "required output torque" in this embodiment.

[0017] The wheel speed sensor 202 detects the rotation speeds (hereinafter referred to as "wheel speeds") WSP of the wheels of the vehicle, for example, the left and right front wheels and rear wheels. The traveling speed of the vehicle, that is, the vehicle speed VSP, can be calculated based on the wheel speeds WSP. In this embodiment, the vehicle speed VSP is calculated based on the wheel speed WSP of the rear wheels, which are driven wheels. The vehicle speed VSP can also be calculated by converting the engine rotation speed using the gear ratio and the dynamic radius of the wheels.

[0018] The inclination angle sensor 203 detects the inclination angle (hereinafter sometimes referred to as "road surface inclination angle") INC of the road on which the vehicle is traveling. Based on the output signal from the inclination angle sensor INC, it is possible to distinguish whether the road is an upward slope or a downward slope and to detect the magnitude of the slope.

[0019] The acceleration sensor 204 detects the acceleration acting on the vehicle. A six-axis inertial sensor (IMU) can be used as the acceleration sensor 204, and the IMU can detect translational acceleration along three mutually orthogonal axes and angular velocities centered on each of these three axes. The acceleration sensor 202 detects the vehicle's forward / rearward acceleration, left / right acceleration, and up / down acceleration, as well as pitching angular velocity, yawing angular velocity, and rolling angular velocity based on these translational acceleration and angular velocities.

[0020] The steering angle sensor 205 detects the steering angle θstr of the vehicle. The steering angle θstr indicates the direction of the front wheels, and specifically, refers to the angle that a straight line perpendicular to the rotation axis of the front wheels (steered wheels) forms with the center line of the vehicle in the longitudinal direction in a plan view of the vehicle seen from above.

[0021] The front camera 301 is installed so that the front of the vehicle fits within its field of view, and can capture the road ahead of the vehicle, and can also capture other vehicles traveling ahead of the vehicle if there are any. The front camera 301 includes, in addition to the road itself, objects installed on the road, such as road markings and roadside signs. In this embodiment, the front camera 301 can analyze the captured image of the road and identify the shape of the road, such as the curvature and width of the road. The front camera 301 is configured as a camera module equipped with an imaging unit and a computing unit, and can be installed inside the vehicle interior by being built into the rearview mirror above the windshield. The front camera 301 and the driving assistance controller 101 are connected to each other so that they can communicate with each other via an in-vehicle network using a CAN protocol or the like.

[0022] In addition to the above, in this embodiment, an activation switch 305 for switching between activation and stop of the driving assistance device 1 is provided. The driving assistance controller 101 receives an output signal from the activation switch 305. The activation switch 305 is installed at a position where the driver can operate it while driving, for example, as one of the steering switches, at a position where the driver who is holding the handlebar (i.e., the steering wheel) can operate it with his / her fingers. The driver can operate the activation switch 305 to activate and stop the driving assistance device 1.

[0023] The engine controller 401 executes a predetermined calculation related to engine control based on a command signal from the driving assistance controller 101, generates a control signal for the engine, and outputs it. The command signal for the engine controller 401 includes a signal related to an output request for the engine (specifically, a requested engine torque). The engine controller 401 sets the amount of fuel supplied to the engine, and drives a fuel injector to control the output torque of the engine.

[0024] The HMI 501 provides the driver with information related to driving assistance control. The information provided by the HMI 501 includes information on the operating status of the system, warnings or alerts based on vehicle driving predictions, and requests for the driver to take action. The information may be provided by visual means, auditory means, or other means that appeal to human senses, such as touch. Furthermore, the information may be provided by a combination of multiple means. In this embodiment, the HMI 501 is equipped with an alarm and a warning light installed in or around the driver's seat, and when there is a risk of the vehicle deviating from the lane while traveling, these devices are activated to encourage the driver to recognize the risk of deviation.

[0025] The steering controller 601 controls the steering angle of the vehicle independently of the driver's steering wheel operation, i.e., the steering. In this embodiment, the steering system of the vehicle is provided with an electric power steering device, and the steering controller 601 is configured as a device that generates and outputs a control signal for the electric power steering device. Specifically, when the driving assistance controller 101 determines that the vehicle is at risk of deviating from the lane, the steering controller 601 controls the electric power steering device based on a command signal from the driving assistance controller 101 so that the vehicle maintains the lane in which it is traveling, in other words, so that the vehicle approaches the center of the lane in which it is traveling.

[0026] FIG. 2 shows a schematic diagram of the internal configuration of the driving assistance controller 101 according to this embodiment.

[0027] In this embodiment, the driving assistance controller 101 includes, as basic elements, a vehicle speed detection unit B101, a required driving torque setting unit B102, an engine output control unit B103, a forward gaze point distance setting unit B104, a lane departure determination unit B105, and a driving assistance control unit B106. The functions of these units are realized in software by a central processing unit included in the driving assistance controller 101 reading a control program stored in a storage device and performing calculations according to the program.

[0028] The vehicle speed detection unit B101 detects the vehicle speed VSP based on the wheel speed WSP detected by the wheel speed sensor 202. The vehicle speed detection unit B101 constitutes a "vehicle speed detection means" according to this embodiment.

[0029] The required drive torque setting unit B102 sets a required output torque for the drive source, which in this embodiment is a required engine torque TRQ that is the output torque for the engine. The required engine torque TRQ can be set based on the accelerator operation amount APO detected by the accelerator opening sensor 201 and the vehicle speed VSP, and is set to a larger value as the accelerator operation amount APO increases, as a tendency across the entire vehicle speed VSP. The required engine torque TRQ is set to a characteristic that is relatively close to linear with respect to the accelerator operation amount APO. The required drive torque setting unit B102 constitutes a "required output torque setting means" in this embodiment.

[0030] The engine output control section B103 generates a command signal according to the requested engine torque TRQ, and outputs it to the engine controller 401.

[0031] The forward gaze point distance setting unit B104 sets a basic value (hereinafter referred to as "basic gaze point distance") Dfgp0 of the forward gaze point distance Dfgp, and corrects the set basic gaze point distance Dfgp0 to set a final forward gaze point distance (hereinafter simply referred to as "forward gaze point distance" or "set gaze point distance") Dfgp. The basic gaze point distance Dfgp0 can be set according to the vehicle speed VSP, and is set to a larger value, that is, a longer distance, as the vehicle speed VSP is higher. In other words, the forward gaze point is basically set to a position farther forward from the vehicle as the vehicle speed VSP is higher, and is set to a position closer forward from the vehicle as the vehicle speed VSP is lower. The basic gaze point distance Dfgp0 is set, for example, according to the following formula (1). TIM is a departure judgment time, and may be constant, or may be adjustable according to the vehicle speed VSP in order to ensure a margin for taking measures such as steering. Dfgp0 = VSP × TIM … (1)

[0032] Then, the forward gaze point distance setting unit B104 corrects the basic gaze point distance Dfgp0 according to the required engine torque TRQ. As a result, the forward gaze point distance Dfgp is set longer than the basic gaze point distance Dfgp0 when the required engine torque TRQ is larger, that is, when the required engine torque TRQ increases from the current torque, and is set shorter than the basic gaze point distance Dfgp0 when the required engine torque TRQ is smaller, that is, when the required engine torque TRQ decreases from the current torque. In other words, the correction of the basic gaze point distance Dfgp0 is performed as an extension correction when the vehicle accelerates, and as a shortening correction when the vehicle decelerates.

[0033] In this embodiment, the forward gaze point distance setting unit B104 corrects the basic gaze point distance Dfgp0 according to the gradient of the road on which the vehicle is traveling (i.e., the road surface inclination angle INC) in addition to the required engine torque TRQ. Specifically, the basic gaze point distance Dfgp0 is set to be longer than the basic gaze point distance Dfgp0 when the vehicle is traveling on a downhill road and the road surface inclination angle INC is larger, while the basic gaze point distance Dfgp0 is set to be shorter than the basic gaze point distance Dfgp0 when the vehicle is traveling on an uphill road and the road surface inclination angle INC is larger. In other words, under a constant accelerator operation amount APO, the correction of the basic gaze point distance Dfgp0 is performed as an extension correction when the vehicle is traveling on a downhill road and has an accelerating tendency, and is performed as a shortening correction when the vehicle is traveling on an uphill road and has a decelerating tendency.

[0034] The forward gaze point distance setting unit B104 constitutes the "forward gaze point distance setting means" and the "forward gaze point distance correction means" according to this embodiment.

[0035] The lane departure determination unit B105 determines whether or not there is a risk that the vehicle will deviate from the lane in which it is traveling, based on the forward fixation point distance Dfgp (hereinafter, referred to as "lane departure determination").

[0036] FIG. 7 shows the operating principle of lane departure judgment, and also shows the parameters related to this judgment.

[0037] Here, as shown in FIG. 7, a situation is assumed in which the vehicle V is traveling on a road (i.e., a left curved road) R that curves to the left in front of it. On the road R, the vehicle V travels on a lane (hereinafter referred to as a "traffic lane") defined by a right boundary line (i.e., a right lane mark) Lr and a left boundary line (i.e., a left lane mark) Ll. Here, a center line Lctr in the vehicle width direction of the traffic lane is virtually shown by a two-dot chain line, and this is set as the original trajectory when the vehicle V travels on the road R. In this embodiment, a case in which the vehicle V follows a trajectory that faces inward closer to the center of curvature of the curve than the center line Lctr, that is, a case of oversteering, is taken as an example to explain a determination of whether or not the vehicle V is likely to deviate from the traffic lane. The trajectory followed by the vehicle V in the example shown in FIG. 7 is shown by a dotted line TRC.

[0038] The lane departure determination unit B105 calculates a lateral movement distance Dlat of the vehicle V at a position (hereinafter referred to as "forward gaze point position") Pf that is forward of the current position Pp by the forward gaze point distance Dfgp, based on an image captured by the forward camera 301 at the current position Pp. The lateral movement distance Dlat indicates the amount of displacement that the vehicle V moves in the vehicle width direction at the current position Pp, that is, along the straight line Lf that defines the forward gaze point position Pf, from the current position Pp to the forward gaze point position Pf. Here, the lateral movement distance Dlat is defined as the distance from a point P1 (hereinafter referred to as "forward gaze point") where the longitudinal center line Actr of the vehicle V at the current position Pp intersects with the straight line Lf that defines the forward gaze point position Pf, to a point P2 (hereinafter referred to as "vehicle passing point") that indicates the position of the vehicle V when passing through the forward gaze point position Pf. The lateral movement distance Dlat can be calculated based on vehicle information at the current position Pp, such as the yawing angular velocity (ie, yaw rate) YAW of the vehicle, and the forward gaze point distance Dfgp.

[0039] The lane departure determination unit B105 further calculates the distance DEV (hereinafter referred to as the "determined lateral deviation") from the vehicle passing point P2 to the boundary line of the driving lane (in this embodiment, the left lane mark) Ll, in other words, the point Pedg where the straight line Lf that defines the forward gaze point position Pf intersects with the left lane mark L1, and compares this with the determination value DEV1. If the determined lateral deviation DEV is equal to or smaller than the determination value DEV1, it is determined that there is a risk of the vehicle V deviating from the driving lane, and if the determined lateral deviation DEV is greater than the determination value DEV1, it is determined that there is no risk of deviation.

[0040] The lane departure determination unit B105 constitutes the "lateral movement distance prediction means" and the "lane departure determination means" according to this embodiment.

[0041] When the lane departure determination unit B105 determines that the vehicle is at risk of deviating from the lane in which it is traveling, the driving assistance control unit B106 outputs a command signal to the HMI 501 to issue a warning of the risk of departure, and also outputs a command signal to the steering controller 601 to steer the steering wheel in a direction to return it to its neutral position, thereby moving the vehicle V closer to the center of the lane in which it is traveling. The driving assistance control unit B106 constitutes the "control signal output means", "alert means" and "steering control means" according to this embodiment.

[0042] Fig. 3 is a flowchart showing an overall flow of lane departure prevention control performed by the driving assistance controller 101. Fig. 4 is a flowchart showing the contents of lane departure prevention processing in the control shown in Fig. 3.

[0043] The driving assistance controller 101 performs lane departure suppression control at a predetermined cycle when the system of the driving assistance device 1 is on, that is, when an instruction to operate the driving assistance device 1 is given by operating the operation switch 305. In this embodiment, in addition to the system of the driving assistance device 1 being on, the lane departure suppression control is performed when predetermined implementation conditions are met, such as the vehicle speed VSP being equal to or higher than a predetermined speed (e.g., 65 km / h or higher), the turn signal is not operating, and the driver has no intention of changing lanes.

[0044] In the flow chart shown in FIG. 3, in S101, various control information related to lane departure suppression control, such as image information acquired by the front camera 301 and vehicle information including the required engine torque TRQ, is read.

[0045] In S102, the basic gaze point distance Dfgp0 is calculated.

[0046] In S103, a change amount of the required engine torque TRQ (hereinafter referred to as a "required torque change amount") ΔTRQ is calculated. In this embodiment, the required torque change amount ΔTRQ is the current value TRQ of the required engine torque TRQ. n and previous value TRQ n-1 The current value of the required engine torque TRQ is calculated as the difference between n means the required engine torque read in the current routine, and the previous value TRQ n-1 This refers to the required engine torque that was read in the previous routine, in other words, in the routine one cycle ago. ΔTRQ=TRQ n -TRQ n-1 …(2)

[0047] In S104, a correction value (hereinafter referred to as "torque correction value") Htrq of the forward gaze point distance corresponding to the required torque change amount ΔTRQ is calculated. The torque correction value Htrq is calculated by searching a data table that is set in advance with a tendency shown in Fig. 5 and stored in the driving assistance controller 101. The torque correction value Htrq is calculated for each of acceleration and deceleration, and is set to a larger value on the acceleration side based on 1 as the required torque change amount ΔTRQ increases, and is set to a smaller value on the deceleration side as the required torque change amount ΔTRQ decreases (in other words, as the absolute value of the required torque change amount ΔTRQ increases).

[0048] In S105, a correction value (hereinafter referred to as "inclination angle correction value") Hinc of the forward gaze point distance corresponding to the road surface inclination angle INC is calculated. The inclination angle correction value Hinc is calculated by searching from a data table that is preset to have a tendency shown in Fig. 6 and stored in the driving assistance controller 101. The inclination angle correction value Hinc is calculated when the vehicle is traveling on a downhill road (when traveling on a downhill road) and when the vehicle is traveling on an uphill road (when traveling on an uphill road), and is set to a smaller value based on 1 as the running resistance increases due to the upward gradient of the road and is set to a larger value as the running resistance decreases due to the downward gradient of the road (in other words, as the inclination angle INC of the downward gradient increases).

[0049] In S106, the basic gaze point distance Dfgp0 is corrected by the torque correction value Htrq and the tilt angle correction value Hinc to calculate the forward gaze point distance Dfgp. In this embodiment, this correction is performed by the following formula (3). Dfgp = Dfgp0 × Htrq × Hinc … (3)

[0050] In S107, the lateral movement distance Dlat of the vehicle V at the forward gaze point position Pf is calculated.

[0051] In S108, a judged lateral deviation DEV of the vehicle V is calculated based on the lateral movement distance Dlat.

[0052] In S109, it is determined whether the determined lateral deviation DEV is equal to or less than a predetermined first determination value DEV1. If the determined lateral deviation DEV is equal to or less than the first determination value DEV1, the process proceeds to S110, and if the determined lateral deviation DEV is greater than the first determination value DEV1, the process of S110 is not performed and the current control is terminated.

[0053] In S110, lane departure prevention processing is carried out according to the procedure shown in the flowchart of FIG.

[0054] 4, in S201, a command signal for activating an alarm and a warning light is output to the HMI 501. As a result, the HMI 501 activates the alarm and the warning light, and prompts the driver to recognize that the vehicle V may deviate from its lane.

[0055] In S202, a steering correction amount δstr for the electric power steering device is calculated. The steering correction amount δstr may be constant or may be variable depending on the driving situation of the vehicle V, such as the determined lateral deviation DEV.

[0056] In S203, the steering correction amount δstr is added to the steering angle STR of the electric power steering device to correct the steering angle STR. Then, the driving assistance controller 101 outputs a command signal according to the corrected steering angle STR to the steering controller 601. As a result, the steering controller 601 drives an electric motor, which is an actuator of the electric power steering device, to generate a torque in a direction to return the direction of the wheels, that is, the steering angle θstr of the vehicle V, to the neutral position. STR = STR + δstr …(4)

[0057] In S204, the lateral movement distance Dlat of the vehicle V is calculated in the same manner as in S107.

[0058] In S205, a judged lateral deviation DEV of the vehicle is calculated in the same manner as in S108.

[0059] In S206, it is determined whether the determined lateral deviation DEV is equal to or greater than a predetermined second determination value DEV2, in other words, whether the determined lateral deviation DEV has recovered and increased to the second determination value DEV2 due to control intervention in the electric power steering device. If the determined lateral deviation DEV is equal to or greater than the second determination value DEV2, the process proceeds to S208, and if it is smaller than the second determination value, the process proceeds to S207. The second determination value DEV2 may be the same as or different from the first determination value DEV1 described above. The second determination value DEV2 can be set to a value greater than the first determination value DEV1.

[0060] In S207, it is determined whether or not a change has occurred in the required engine torque TRQ, in other words, whether or not a change has occurred in the accelerator operation amount APO due to the driver depressing and releasing the accelerator pedal during the execution of the lane departure prevention process. If a change has occurred in the required engine torque TRQ, the process proceeds to S208, and the lane departure prevention process is temporarily terminated, whereas if no change has occurred, the process returns to S202, and the lane departure prevention process, specifically, the control intervention by S202 and S203, continues. If the lane departure prevention process has ended, the process returns to the flowchart of FIG. 3, and lane departure determination is resumed by the steps shown in S101 to S109.

[0061] In S208, a command signal is output to the HMI 501 to stop the alarm and the warning light.

[0062] The driving assistance device for the vehicle V according to this embodiment has the above-mentioned configuration. Effects obtained by this embodiment will be described below.

[0063] First, a required output torque (required engine torque TRQ in this embodiment) for the drive source of the vehicle is set, and the forward gaze point distance Dfgp set based on the vehicle speed VSP is corrected according to the required engine torque TRQ. Then, a lateral movement distance Dlat of the vehicle at a position forward of the corrected forward gaze point distance Dfgp from the vehicle is predicted, and deviation of the vehicle from the lane in which it is traveling is determined based on the predicted lateral movement distance Dlat.

[0064] In this way, by correcting the forward gaze point distance Dfgp, which is set based on the vehicle speed VSP, in accordance with the required engine torque TRQ, the forward gaze point distance Dfgp can be made appropriate for the vehicle speed VSP after acceleration or deceleration due to a change in the required engine torque TRQ, making it possible to determine whether the vehicle has departed from the lane at a more appropriate time.

[0065] Here, by correcting the forward gaze point distance DFGP according to the required engine torque TRQ, it becomes possible to determine whether the vehicle is deviating from the lane before the vehicle speed VSP actually changes. This makes it possible to avoid situations where a delay in the determination causes a driver to be unable to take action by steering in time, or where the determination is made unnecessarily early, causing the driver to feel annoyed.

[0066] Secondly, when the required engine torque TRQ is large, the forward gaze point distance Dfgp is extended and the forward gaze point distance Dfgp is set to a longer value, while when the required engine torque TRQ is small, the forward gaze point distance Dfgp is shortened and the forward gaze point distance Dfgp is set to a shorter value, thereby making it possible to optimize the forward gaze point distance Dfgp.

[0067] Third, by correcting the forward gaze point distance Dfgp according to the vehicle's running resistance in addition to the required engine torque TRQ, it is possible to make a judgment at a more appropriate timing, taking into account the effect of running resistance on changes in vehicle speed VSP.

[0068] Specifically, in a situation where the running resistance is large and it is difficult to achieve the vehicle speed VSP, the forward gaze point distance Dfgp is shortened, whereas in a situation where the running resistance is small and it is easy to achieve the vehicle speed VSP, the forward gaze point distance Dfgp is extended. For example, when traveling on an uphill road where it is difficult to achieve the vehicle speed VSP, the forward gaze point distance Dfgp is shortened and the forward gaze point distance Dfgp is set to be short. On the other hand, when traveling on a downhill road where it is easy to achieve the vehicle speed VSP, the forward gaze point distance Dfgp is extended and the forward gaze point distance Dfgp is set to be long. This makes it possible to set the forward gaze point distance Dfgp appropriate for the actual vehicle speed VSP for the required engine torque TRQ.

[0069] When correcting the forward gaze point distance Dfgp in accordance with the vehicle's running resistance, in addition to making it conform to the vehicle speed VSP actually obtained under the required engine torque TRQ, it is possible to avoid a situation in which, when the running resistance is high, the driver does not achieve the acceleration he or she expected, which causes the accelerator pedal to be pressed hard, resulting in an excessive extension of the forward gaze point distance Dfgp.

[0070] On the other hand, when the running resistance is small, the change in actual vehicle speed VSP relative to the required engine torque TRQ is large, which results in a lack of correction (i.e., extension) of the forward gaze point distance Dfgp by the required engine torque TRQ, making it possible to avoid a situation in which, for example, the forward gaze point distance Dfgp is set too close to the vehicle even when accelerating.

[0071] Fourth, when it is determined that the vehicle is at risk of deviating from its lane, a control signal can be output to devices such as the HMI 501 or the steering controller 601 at a more appropriate timing to alert the driver to the risk of deviation or to prevent the vehicle from deviating by automatic steering, thereby enabling the vehicle to maintain its lane.

[0072] In this embodiment, a case has been described in which the gradient of the road R, that is, the road surface inclination angle INC, is taken into consideration as a factor related to the correction of the headway point distance Dfgp in addition to the required engine torque TRQ. However, this correction factor is not limited to the road surface inclination angle INC, and may be another factor related to the running resistance of the vehicle V. For example, it is possible to take into consideration the influence of the wind flowing around the vehicle V. Specifically, when the surrounding wind is in the forward direction with respect to the traveling direction of the vehicle V and the vehicle V is receiving a tailwind, the running resistance is determined to be small and a correction is made to extend the headway point distance Dfgp, whereas when the surrounding wind is in the opposite direction to the traveling direction of the vehicle V and the vehicle V is receiving a headwind, the running resistance is determined to be large and a correction is made to shorten the headway point distance Dfgp. [Explanation of symbols]

[0073] V...vehicle, driving assistance device...1, 101...controller, 201...accelerator opening sensor, 202...vehicle speed sensor, 203...inclination angle sensor, 204...acceleration sensor, 205...steering angle sensor, 301...forward camera, 305...operation switch, 401...engine controller, 501...HMI (human machine interface), 601...steering controller.

Claims

1. a required output torque setting means for setting a required output torque for a drive source of the vehicle; A vehicle speed detection means for detecting a vehicle speed; a forward gaze point distance setting means for setting a forward gaze point distance of the vehicle based on the vehicle speed detected by the vehicle speed detection means; a front gaze point distance correcting means for correcting the front gaze point distance set by the front gaze point distance setting means in accordance with the required output torque set by the required output torque setting means; a lateral movement distance prediction means for predicting a lateral movement distance of the vehicle at a position forward of the forward gaze point distance corrected by the forward gaze point distance correction means; and lane departure determination means for determining whether the vehicle has deviated from the lane in which it is traveling, based on the lateral movement distance predicted by the lateral movement distance prediction means.

2. 2. The lane departure determination device for a vehicle according to claim 1, wherein the forward gaze point distance correction means extends the forward gaze point distance as the required output torque increases, and shortens the forward gaze point distance as the required output torque decreases.

3. 2. The lane departure judgment device according to claim 1, wherein the forward gaze point distance correction means further corrects the forward gaze point distance in accordance with the running resistance of the vehicle, shortening the forward gaze point distance as the running resistance increases and extending the forward gaze point distance as the running resistance decreases.

4. 2. The lane departure judgment device for a vehicle according to claim 1, wherein the forward gaze point distance correction means further corrects the forward gaze point distance in accordance with the gradient of the road on which the vehicle is traveling, and when traveling downhill, the forward gaze point distance is extended the greater the downward gradient of the road, and when traveling uphill, the forward gaze point distance is shortened the greater the upward gradient of the road.

5. The lane departure determination device for a vehicle according to any one of claims 1 to 4, a control signal output means for outputting a control signal for a departure from a lane when the lane departure determination means determines that the vehicle has departed from the lane.

6. 6. The vehicle driving assistance device according to claim 5, further comprising a notification unit that issues a notification to encourage a driver to recognize that the vehicle is deviating from a lane, in response to the control signal output by the control signal output unit.

7. 6. The vehicle driving assistance device according to claim 5, further comprising a steering control means for automatically controlling a steering angle of the vehicle so as to move the vehicle closer to the center of the lane in which the vehicle is traveling, in response to the control signal output by the control signal output means.

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