Vehicle driving assistance device, vehicle driving assistance method, and vehicle driving assistance program

Abstract

To provide a vehicle driving assistance device that is able to prevent giving a sense of incongruity to an operator of an own vehicle when stopping steering assistance control.SOLUTION: A vehicle driving assistance device 10 executes a rapid decrease restriction control when an actual additional torque, which is a steering assistance torque added to a steering operation at a point in time that a traveling road boundary cannot be recognized, is larger than zero. The rapid decrease restriction control is a control to reduce the actual additional torque by a predetermined rapid decrease restriction value per unit time from the actual additional torque at the point in time that the traveling road boundary cannot be recognized, or is a control to add, to the steering operation, a steering assistance torque that is set using, as a limit steering angle, an angle increased by a predetermined rapid decrease restriction angle per unit time from a limit steering angle set by the steering assistance control at the point in time that the traveling road boundary cannot be recognized.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle driving assistance device, a vehicle driving assistance method, and a vehicle driving assistance program. [Background technology]

[0002] A vehicle driving assistance device has been applied for that performs steering assistance control to add a steering assistance torque that resists the steering operation to assist the steering operation performed by the operator of the vehicle (see, for example, Patent Application No. 2023-61204). Summary of the Invention

[0003] In the above-described conventional vehicle driving assistance device, when the steering assist control is stopped, the steering assist torque applied to the steering operation suddenly becomes zero, which may cause an uncomfortable feeling to the operator of the vehicle.

[0004] An object of the present invention is to provide a vehicle driving assistance device, a vehicle driving assistance method, and a vehicle driving assistance program that can prevent the operator of the vehicle from feeling uncomfortable when steering assistance control is stopped.

[0005] A vehicle driving assistance device according to the present invention includes a control device that executes steering assist control to apply a steering assist torque that resists a steering operation performed by an operator of a host vehicle to the steering operation in order to assist the steering operation. The control device is configured to execute the steering assist control when a lane boundary, which is a boundary that defines the lane in which the host vehicle is traveling, can be recognized, and to stop the steering assist control when the lane boundary cannot be recognized. The steering assist control sets a limit steering angle based on the position of the host vehicle relative to the lane boundary, and when the actual steering angle of the host vehicle is greater than the limit steering angle, applies the steering assist torque to the steering operation, the value of which is set based on the difference between the limit steering angle and the actual steering angle. Furthermore, the control device is configured to execute sudden deceleration suppression control when the actual added torque, which is the steering assist torque applied to the steering operation at the time when the lane boundary cannot be recognized, is greater than zero. The sudden decrease suppression control is a control that reduces the actual added torque by a predetermined sudden decrease suppression value per unit time from the actual added torque at the time when the lane boundary can no longer be recognized, or a control that adds to the steering operation the steering assist torque that is set using as the limit steering angle an angle that is increased by a predetermined sudden decrease suppression angle per unit time from the limit steering angle set by the steering assist control at the time when the lane boundary can no longer be recognized.

[0006] According to the vehicle driving assistance device of the present invention, when the steering assist control is stopped, the sudden decrease suppression control is executed. If such sudden decrease suppression control is not executed, the steering assist torque applied to the steering operation suddenly becomes zero, which may cause the operator of the vehicle to feel uncomfortable. However, according to the vehicle driving assistance device of the present invention, when the sudden steering assist control is stopped, the decrease suppression control is executed, and the steering assist torque applied to the steering operation is gradually reduced. Therefore, it is possible to prevent the operator of the vehicle from feeling uncomfortable when the steering assist control is stopped.

[0007] In the vehicle driving assistance device according to the present invention, the control device may be configured to, when the steering assist torque set by the steering assist control at the time when the lane boundary becomes recognizable after the lane boundary becomes recognizable is greater than the actual added torque at that time, perform a sudden increase suppression control and then perform the steering assist control. In this case, the sudden increase suppression control is control that increases the actual added torque by a predetermined sudden increase suppression value per unit time, or control that applies to the steering operation the steering assist torque that is set by using, as the limit steering angle, an angle that is reduced by a predetermined sudden increase suppression angle per unit time from the actual steering angle at the time when the lane boundary becomes recognizable.

[0008] When the lane boundary becomes recognizable after it has become impossible to recognize the lane boundary, the sudden increase suppression control is executed, and then the steering assist control is executed. If such sudden increase suppression control is not executed, a relatively large steering assist torque will be suddenly applied to the steering operation, which may cause the operator of the host vehicle to feel uncomfortable. However, according to the vehicle driving assist device of the present invention, the sudden increase suppression control is executed before the steering assist control is started, and the steering assist torque applied to the steering operation is gradually increased. Therefore, it is possible to suppress the operator of the host vehicle from feeling uncomfortable when the steering assist control is started.

[0009] A vehicle driving assistance method according to the present invention is a method for executing steering assist control to add a steering assist torque that resists the steering operation to assist a steering operation performed by an operator of the vehicle. The vehicle driving assistance method according to the present invention includes the steps of: executing the steering assist control when a lane boundary, which is a boundary that defines the lane in which the vehicle is traveling, can be recognized; and stopping the steering assist control when the lane boundary cannot be recognized. The steering assist control is a control that sets a limit steering angle based on the position of the vehicle relative to the lane boundary, and when the actual steering angle of the vehicle is greater than the limit steering angle, adds the steering assist torque to the steering operation, the value of which is set based on the difference between the limit steering angle and the actual steering angle. The vehicle driving assistance method according to the present invention further includes the step of executing sudden deceleration suppression control when the actual added torque, which is the steering assist torque added to the steering operation at the time when the lane boundary cannot be recognized, is greater than zero. The sudden decrease suppression control is a control that reduces the actual added torque by a predetermined sudden decrease suppression value per unit time from the actual added torque at the time when the lane boundary can no longer be recognized, or a control that adds to the steering operation the steering assist torque that is set using as the limit steering angle an angle that is increased by a predetermined sudden decrease suppression angle per unit time from the limit steering angle set by the steering assist control at the time when the lane boundary can no longer be recognized.

[0010] According to the vehicle driving assistance method of the present invention, it is possible to prevent the driver from feeling uncomfortable when the steering assist control is stopped.

[0011] A vehicle driving assistance program according to the present invention is a program that executes steering assist control to apply a steering assist torque that resists the steering operation to the steering operation performed by an operator of the vehicle in order to assist the steering operation. The vehicle driving assistance program according to the present invention is configured to execute the steering assist control when a lane boundary, which is a boundary that defines the lane in which the vehicle is traveling, can be recognized, and to stop the steering assist control when the lane boundary cannot be recognized. The steering assist control sets a limit steering angle based on the position of the vehicle relative to the lane boundary, and when the actual steering angle of the vehicle is greater than the limit steering angle, applies the steering assist torque to the steering operation, the value of which is set based on the difference between the limit steering angle and the actual steering angle. Furthermore, the vehicle driving assistance program according to the present invention is configured to execute sudden deceleration suppression control when the actual added torque, which is the steering assist torque applied to the steering operation at the time when the lane boundary cannot be recognized, is greater than zero. The sudden decrease suppression control is a control that reduces the actual added torque by a predetermined sudden decrease suppression value per unit time from the actual added torque at the time when the lane boundary can no longer be recognized, or a control that adds to the steering operation the steering assist torque that is set using as the limit steering angle an angle that is increased by a predetermined sudden decrease suppression angle per unit time from the limit steering angle set by the steering assist control at the time when the lane boundary can no longer be recognized.

[0012] According to the vehicle driving assistance program of the present invention, it is possible to prevent the driver from feeling uncomfortable when the steering assistance control is stopped.

[0013] The components of the present invention are not limited to the embodiments of the present invention described below with reference to the drawings. Other objects, features, and attendant advantages of the present invention will be easily understood from the description of the embodiments of the present invention. [Brief explanation of the drawings]

[0014] [Figure 1]FIG. 1 is a diagram showing a vehicle driving assistance device according to an embodiment of the present invention. [Figure 2] Figure 2 shows the lane boundaries. [Figure 3] FIG. 3 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the transition of the actual additional torque realized by the vehicle driving assistance device according to the present invention when a lane boundary is recognized. [Figure 5] FIG. 5 is a diagram showing one example of the transition of the actual additional torque realized by the vehicle driving assistance device according to the present invention when the lane boundary is no longer recognized. [Figure 6] FIG. 6 is a diagram showing another example of the transition of the actual additional torque realized by the vehicle driving assistance device according to the present invention when the lane boundary is no longer recognized. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, a vehicle driving assistance device, a vehicle driving assistance method, and a vehicle driving assistance program according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a vehicle driving assistance device 10 according to an embodiment of the present invention. The vehicle driving assistance device 10 is mounted on a host vehicle 100. Hereinafter, the vehicle driving assistance device 10 will be described using as an example a case where the operator of the host vehicle 100 is a person who gets into the host vehicle 100 and drives the host vehicle 100 (i.e., the driver of the host vehicle 100).

[0016] However, the operator of the vehicle 100 may be a person who drives the vehicle 100 remotely without being in the vehicle 100 (i.e., a remote operator of the vehicle 100). When the operator of the vehicle 100 is a remote operator, the vehicle driving assistance device 10 is mounted on the vehicle 100 and on a remote operation facility installed outside the vehicle 100 for remotely driving the vehicle 100, and the functions of the vehicle driving assistance device 10 described below are shared between the vehicle driving assistance device 10 mounted on the vehicle 100 and the vehicle driving assistance device 10 mounted on the remote operation facility.

[0017] As shown in FIG. 1, the vehicle driving assistance device 10 includes an ECU (electronic control unit) 90 as a control device. The ECU 90 includes a microcomputer as a main component. The microcomputer includes a CPU, storage media such as a ROM, a RAM, and a non-volatile memory, as well as an interface. The CPU executes instructions, programs, or routines stored in the storage media to realize various functions. In particular, in this example, the vehicle driving assistance device 10 stores programs in the storage media that realize various controls executed by the vehicle driving assistance device 10.

[0018] In this example, the vehicle driving assistance device 10 has only one ECU 90, but it may also be configured to have multiple ECUs, with each ECU sharing the functions of the vehicle driving assistance device 10 described below.

[0019] Furthermore, the vehicle driving assistance device 10 may be configured so that the program stored in the storage medium can be updated via wireless communication with an external device (for example, via the Internet).

[0020] The host vehicle 100 is equipped with a steering device 20, a steering wheel 31, a steering shaft 32, a steering angle sensor 33, a vehicle momentum detection device 40, and a surrounding information detection device 50. The surrounding information detection device 50 is a device that detects information related to the surroundings of the host vehicle 100, and in this example, includes an image sensor 51. The steering device 20, the steering angle sensor 33, the vehicle momentum detection device 40, and the image sensor 51 are each electrically connected to the ECU 90.

[0021] The vehicle driving assistance device 10 controls the operation of the steering device 20 to control the steering assistance torque that is applied to the steering operation performed by the driver of the vehicle 100 in opposition to the steering operation. The steering operation is an operation in which the driver turns the steering wheel 31 to steer the vehicle 100.

[0022] The vehicle driving assistance device 10 also acquires the rotation angle of the steering shaft 32 with respect to the neutral position as the actual steering angle δa from the steering angle sensor 33. Furthermore, the vehicle driving assistance device 10 also acquires steering angle information such as the steering angle angular velocity based on the actual steering angle δa.

[0023] Furthermore, the vehicle driving assistance device 10 acquires information (vehicle state information) related to the momentum of the host vehicle 100 using the vehicle momentum detection device 40. The momentum of the host vehicle 100 includes, for example, the running speed, lateral speed, lateral acceleration, longitudinal acceleration, and yaw rate of the host vehicle 100.

[0024] The image sensor 51 is a sensor, such as a camera, that captures an image of the surroundings of the vehicle 100. The vehicle driving assistance device 10 uses the image sensor 51 to capture an image of the surroundings of the vehicle 100 and acquires information (image information) related to the captured image as surrounding information IS. The vehicle driving assistance device 10 also acquires lane boundary information, such as information related to lane boundaries TB (to be described later) and the positional relationship between the vehicle 100 and each lane boundary TB, based on the surrounding information IS. In particular, the vehicle driving assistance device 10 recognizes lane boundaries TB based on the surrounding information IS.

[0025] <Operation of vehicle driving assistance device> Next, the operation of the vehicle driving assistance device 10 will be described. The vehicle driving assistance device 10 is configured to execute steering assist control when it is able to recognize the lane boundary TB. In particular, in this example, the vehicle driving assistance device 10 is configured to execute steering assist control when it is able to recognize both the left lane boundary TB_L and the right lane boundary TB_R. However, it may also be configured to execute steering assist control when it is able to recognize at least one of the left lane boundary TB_L and the right lane boundary TB_R.

[0026] The steering assist control is a control that adds a steering assist torque that resists the steering operation to the steering operation performed by the driver of the vehicle 100 in order to assist the steering operation.

[0027] The lane boundary TB is a boundary that defines the lane in which the host vehicle 100 is traveling. The lane boundary TB is, for example, a left lane marking LM_L and a right lane marking LM_R that are made up of white lines or the like that define the lane in which the host vehicle 100 is traveling, as shown in FIG. 2. In particular, the left lane boundary TB_L is, for example, the left lane marking LM_L shown in FIG. 2, and the right lane boundary TB_R is, for example, the right lane marking LM_R shown in FIG. 2. In addition, when another vehicle, such as a truck, is traveling parallel to the host vehicle 100 in a lane adjacent to the lane in which the host vehicle 100 is traveling, the lane boundary TB may be the side wall surface of the other vehicle on the host vehicle 100 side.

[0028] When the vehicle driving assistance device 10 starts the steering assistance control, it sets a left limit steering angle δlim_L and a right limit steering angle δlim_R as the limit steering angle δlim based on the vehicle state information, the lane boundary information, and the like.

[0029] When the actual steering angle δa when the driver is turning the steering wheel 31 counterclockwise is greater than the left limit steering angle δlim_L, the vehicle driving assistance device 10 sets a clockwise steering assist torque TQ whose value increases as the difference between the left limit steering angle δlim_L and the actual steering angle δa increases, and applies the clockwise steering assist torque TQ to the steering operation (more specifically, to the steering shaft 32). On the other hand, when the actual steering angle δa when the driver is turning the steering wheel 31 clockwise is greater than the right limit steering angle δlim_R, the vehicle driving assistance device 10 sets a counterclockwise steering assist torque TQ whose value increases as the difference between the right limit steering angle δlim_R and the actual steering angle δa increases, and applies the counterclockwise steering assist torque TQ to the steering operation (more specifically, to the steering shaft 32).

[0030] According to this, as shown in Figure 4, when the driver is turning the steering wheel 31 counterclockwise from its neutral position, if the actual steering angle δa is greater than the left limit steering angle δlim_L, a right-turn steering assist torque TQ is added to the steering operation. That is, the right-turn steering assist torque TQ added to the steering operation becomes greater than zero. On the other hand, when the driver is turning the steering wheel 31 clockwise from its neutral position, if the actual steering angle δa is greater than the right limit steering angle δlim_R, a left-turn steering assist torque TQ is added to the steering operation. That is, the left-turn steering assist torque TQ added to the steering operation becomes greater than zero.

[0031] In the example shown in Figure 4, a left-hand steering operation is started at time t40, and from time t41 to time t42, the actual steering angle δa is larger than the left limit steering angle δlim_L, and therefore the right-hand steering assist torque TQ added to the steering operation is larger than zero.

[0032] In this way, the vehicle driving assistance device 10 sets the limit steering angle δlim based on the position of the vehicle 100 relative to the lane boundary TB, and when the actual steering angle δa of the vehicle 100 is greater than the limit steering angle δlim, it is configured to add a steering assistance torque TQ of a value set based on the difference between the limit steering angle δlim and the actual steering angle δa to the steering operation.

[0033] The left limit steering angle δlim_L is set to a smaller value as the host vehicle 100 approaches the left lane boundary TB_L, and the right limit steering angle δlim_R is set to a smaller value as the host vehicle 100 approaches the right lane boundary TB_R. That is, the left limit steering angle δlim_L is set based on the position of the host vehicle 100 relative to the left lane boundary TB_L, and the right limit steering angle δlim_R is set based on the position of the host vehicle 100 relative to the right lane boundary TB_R.

[0034] In this example, the actual steering angle δa is a positive value whether the steering wheel 31 is operated counterclockwise or clockwise relative to its neutral position, and therefore the left limit steering angle δlim_L and the right limit steering angle δlim_R are both set to positive values. The limit steering angle δlim is used to set the steering assist torque TQ to be added to the steering operation so that the vehicle 100 does not cross the lane boundary TB, and can be set by various known methods (for example, the method described in Japanese Patent Application No. 2023-61204).

[0035] Furthermore, the vehicle driving assistance device 10 executes the routine shown in Fig. 3 at predetermined time intervals, and when predetermined conditions are met, executes sudden change suppression control. The sudden change suppression control is control that suppresses a sudden change in the steering assist torque.

[0036] At a predetermined timing, the vehicle driving assistance device 10 starts processing from step S300 of the routine shown in FIG. 3, proceeds to step S305, and determines whether a non-recognition condition C1 is satisfied. The non-recognition condition C1 is a condition in which at least one of the left lane boundary TB_L and the right lane boundary TB_R is no longer recognized. Situations in which the non-recognition condition C1 is satisfied include, for example, a situation in which the host vehicle 100 is traveling on a sharply curved road or a situation in which a lane marking such as a white line is blurred. However, even if the host vehicle 100 is not traveling on a straight road or the lane marking is not blurred, the non-recognition condition C1 may also be satisfied depending on the orientation of the host vehicle 100 with respect to the road, etc.

[0037] If the vehicle driving assistance device 10 determines "Yes" in step S305, the process proceeds to step S310, where it stops the steering assistance control and executes sudden decrease suppression control as sudden change suppression control, which suppresses a sudden decrease in the steering assistance torque TQ. That is, the vehicle driving assistance device 10 is configured to stop the steering assistance control and execute sudden decrease suppression control when it becomes unable to recognize the lane boundary TB. Next, the vehicle driving assistance device 10 proceeds to step S315, where it sets the value of the non-recognition flag X to "1." Next, the vehicle driving assistance device 10 proceeds to step S395, where it temporarily ends the processing of this routine.

[0038] The sudden decrease suppression control is (1) a control that, when the steering assist torque TQ (actual added torque TQa) actually added to the steering operation at the time when at least one of the left lane boundary TB_L and the right lane boundary TB_R is no longer recognized (non-recognition time), reduces the actual added torque TQa by a predetermined value (sudden decrease suppression value TQd) per unit time from the actual added torque TQa at the non-recognition time, or (2) a control that adds to the steering operation a steering assist torque TQ that is set using as the limit steering angle δlim an angle that is increased by a predetermined angle (sudden decrease suppression angle δd) per unit time from the limit steering angle δlim set by the steering assist control at the non-recognition time.

[0039] More specifically, as shown in Figure 5, the sudden decrease suppression control is a control in which, when the steering wheel 31 is operated counterclockwise and the actual added torque TQa in the clockwise direction at the non-recognition time point is greater than zero, the actual added torque TQa in the clockwise direction is reduced by a predetermined value (first sudden decrease suppression value TQd_1) per unit time from the actual added torque TQa in the clockwise direction at the non-recognition time point, and when the steering wheel 31 is operated clockwise and the actual added torque TQa in the counterclockwise direction at the non-recognition time point is greater than zero, the actual added torque TQa in the counterclockwise direction is reduced by a predetermined value (second sudden decrease suppression value TQd_2) per unit time from the actual added torque TQa in the counterclockwise direction at the non-recognition time point.

[0040] 5, the counterclockwise steering operation is started at time t50, the actual steering angle δa becomes larger than the left limit steering angle δlim_L at time t51, the left lane boundary TB_L is no longer recognized at time t52, and the actual added torque TQa in the clockwise direction gradually decreases due to the sudden decrease suppression control from time t52 to time t53. Also, at time t53, the actual added torque TQa in the clockwise direction reaches zero.

[0041] Alternatively, as shown in Figure 6, the sudden deceleration suppression control is a control that adds to the steering operation a right-turn steering assist torque TQ that is set by using as the left limit steering angle δlim_L an angle that is increased by a predetermined angle per unit time (first sudden deceleration suppression angle δd_1) from the left limit steering angle δlim_L set by the steering assist control at the time of non-recognition when the steering wheel 31 is being operated leftward, and adds to the steering operation a left-turn steering assist torque TQ that is set by using as the right limit steering angle δlim_R an angle that is increased by a predetermined angle per unit time (second sudden deceleration suppression angle δd_2) from the right limit steering angle δlim_R when the steering wheel 31 is being operated rightward.

[0042] 6, the steering operation to the left is started at time t60, the actual steering angle δa becomes larger than the left limit steering angle δlim_L at time t61, the left lane boundary TB_L is no longer recognized at time t62, and the left limit steering angle δlim_L gradually increases from time t52 to time t53 due to the sudden decrease suppression control, and therefore the actual torque added in the right direction TQa gradually decreases. Also, at time t63, the left limit steering angle δlim_L set by the sudden decrease suppression control reaches the actual steering angle δa, and therefore the actual torque added in the right direction TQa reaches zero.

[0043] The first sudden decrease suppression value TQd_1 and the second sudden decrease suppression value TQd_2 may be constant values, or may be set according to the following formulas 1 and 2, respectively.

[0044] TQd_1=TQa_R_lost / Td …(1) TQd_2=TQa_L_lost / Td …(2)

[0045] In Equation 1, "TQa_R_lost" is the actual clockwise applied torque TQa at the time of non-recognition, and in Equation 2, "TQa_L_lost" is the actual counterclockwise applied torque TQa at the time of non-recognition. Furthermore, in Equations 1 and 2, "Td" is a time (target transition time) that is set in advance as a target value for the time from when the sudden decrease suppression control is started until the actual applied torque TQa reaches zero.

[0046] Furthermore, when the sudden deceleration suppression control is a control that adds to the steering operation a steering assist torque TQ that is set using as the limit steering angle δlim an angle that is increased by the sudden deceleration suppression angle δd per unit time from the limit steering angle δlim set by the steering assist control at the time of non-recognition, the left limit steering angle δlim_L and right limit steering angle δlim_R set by the sudden deceleration suppression control may be set to constant values ​​for the first sudden deceleration suppression angle δd_1 and the second sudden deceleration suppression angle δd_2, respectively, or may be set according to the following equations 3 and 4.

[0047] δlim_L=α·δlim_L_lost+(1-α)·δa …(3) δlim_R=α·δlim_R_lost+(1-α)·δa …(4)

[0048] In Equation 3, "δlim_L_lost" is the left limit steering angle δlim_L set by the steering assist control at the time of non-recognition, and "δlim_R_lost" is the right limit steering angle δlim_R set by the steering assist control at the time of non-recognition. Also, in Equation 3 and Equation 4, "α" is a coefficient and is obtained according to Equation 5 below.

[0049] α=Tlost / Td …(5)

[0050] In Equation 5, "Tlost" is the time that has elapsed since the sudden decrease suppression control was started.

[0051] Alternatively, the sudden decrease suppression control may be a control in which, when the steering assist torque TQ set by the steering assist control at the time of non-recognition is greater than zero, the steering assist torque TQ is set using as the limit steering angle δlim an angle that is increased by the sudden decrease suppression angle δd per unit time from the limit steering angle δlim set by the steering assist control at the time of non-recognition, and when the amount of decrease in the actual added torque TQa per unit time when the set steering assist torque TQ is applied to the steering operation is less than the sudden decrease suppression value TQd, and when the amount of decrease in the actual added torque TQa per unit time when the set steering assist torque TQ is applied to the steering operation is greater than the sudden decrease suppression value TQd, a steering assist torque TQ is applied to the steering operation such that the amount of decrease in the actual added torque TQa per unit time becomes the sudden decrease suppression value TQd.

[0052] In this way, the sudden decrease suppression control is control that reduces the actual additional torque TQa from the actual additional torque TQa at the non-recognition time by a predetermined sudden decrease suppression value TQd per unit time, or control that adds to the steering operation a steering assist torque TQ that is set using, as the limit steering angle δlim, an angle that is increased by the sudden decrease suppression angle δd per unit time from the limit steering angle δlim set by the steering assist control at the non-recognition time. The vehicle driving assist device 10 is configured to execute the sudden decrease suppression control when the actual additional torque TQa at the non-recognition time is greater than zero.

[0053] On the other hand, if the determination in step S305 is "No," the vehicle driving assistance device 10 proceeds to step S320, where it determines whether the value of the non-recognition flag X is "1."

[0054] If the determination in step S320 is "Yes," the vehicle driving assistance device 10 proceeds to step S325. That is, if the vehicle driving assistance device 10 becomes able to recognize both the left lane boundary TB_L and the right lane boundary TB_R after being unable to recognize at least one of the left lane boundary TB_L and the right lane boundary TB_R, the vehicle driving assistance device 10 proceeds to step S325.

[0055] When the process proceeds to step S325, the vehicle driving assistance device 10 ends the sudden decrease suppression control and executes, as the sudden change suppression control, a sudden increase suppression control that suppresses a sudden increase in the steering assist torque TQ. Next, the vehicle driving assistance device 10 proceeds to step S330.

[0056] The sudden increase suppression control is (1) a control in which, when the steering assist torque TQ set by the steering assist control at the time when both the left lane boundary TB_L and the right lane boundary TB_R are recognized (the time of re-recognition) is greater than the actual added torque TQa at the time of re-recognition, the actual added torque TQa is increased by a predetermined value (sudden increase suppression value TQu) per unit time from the actual added torque TQa at the time of re-recognition, or (2) a control in which a steering assist torque TQ set using a limit steering angle δlim, which is an angle that is reduced by a predetermined angle (sudden increase suppression angle δu) per unit time from the actual steering angle δa at the time of re-recognition, is added to the steering operation.

[0057] More specifically, as shown in Figure 5, the sudden increase suppression control is a control in which, when the steering wheel 31 is being operated counterclockwise and the right-turn steering assist torque TQ set by the steering assist control at the time of re-recognition is greater than the actual right-turn steering additional torque TQa at the time of re-recognition, the right-turn actual additional torque TQa is increased by a predetermined value (first sudden increase suppression value TQu_1) per unit time from the actual right-turn steering additional torque TQa at the time of re-recognition, and when the steering wheel 31 is being operated clockwise and the left-turn steering assist torque TQ set by the steering assist control at the time of re-recognition is greater than the actual left-turn steering additional torque TQa at the time of re-recognition, the counterclockwise actual additional torque TQa is increased by a predetermined value (second sudden increase suppression value TQu_2) per unit time from the actual left-turn steering additional torque TQa at the time of re-recognition.

[0058] 5, after the left lane boundary TB_L is no longer recognized at time t52, the left lane boundary TB_L is recognized at time t54, and the actual clockwise additional torque TQa gradually increases from time t54 to time t55 due to the sudden increase suppression control. Also, at time t55, the actual clockwise additional torque TQa reaches the counterclockwise steering assist torque TQ set by the steering assist control, the sudden increase suppression control is ended, and the steering assist control is started.

[0059] Alternatively, as shown in FIG. 6, the sudden increase suppression control is a control in which, when the steering wheel 31 is operated counterclockwise, a right-turn steering assist torque TQ is added to the steering operation, and the right-turn steering assist torque TQ is set by using, as the left limit steering angle δlim_L, an angle that is reduced by a predetermined angle (first sudden increase suppression angle δu_1) per unit time from the actual steering angle δa at the time of re-recognition, and a right-turn steering assist torque TQ is added to the steering operation, and the right-turn steering assist torque TQ is set by using, as the right limit steering angle δlim_R, an angle that is reduced by a predetermined angle (second sudden increase suppression angle δu_2) per unit time from the actual steering angle δa at the time of re-recognition, when the steering wheel 31 is operated clockwise.

[0060] 6, after the left lane boundary TB_L is no longer recognized at time t62, the left lane boundary TB_L is recognized at time t64, and from time t64 to time t65, the left limit steering angle δlim_L gradually decreases due to the sudden increase suppression control, and therefore the actual clockwise additional torque TQa gradually increases. Also, at time t65, the left limit steering angle δlim_L set by the sudden increase suppression control reaches the left limit steering angle δlim_L set by the steering assist control, the sudden increase suppression control is ended, and the steering assist control is started.

[0061] The first sudden increase suppression value TQu_1 and the second sudden increase suppression value TQu_2 may be constant values, or may be set according to the following equations 6 and 7, respectively.

[0062] TQu_1=TQa_R_req / Tu …(6) TQu_2=TQa_L_req / Tu …(7)

[0063] In Equation 6, "TQa_R_req" is the actual clockwise additional torque TQa at the time of re-recognition, and "TQa_L_req" is the actual counterclockwise additional torque TQa at the time of re-recognition. Also, in Equation 6 and Equation 7, "Tu" is a time (target transition time) that is set in advance as a target value for the time from when the sudden increase suppression control is started until the actual additional torque TQa reaches the steering assist torque TQ set by the steering assist control.

[0064] Furthermore, when the sudden increase suppression control is a control that adds to the steering operation a steering assist torque TQ that is set as a limit steering angle δlim, which is an angle that is reduced by a sudden increase suppression angle δu per unit time from the actual steering angle δa at the time of re-recognition, the left limit steering angle δlim_L and the right limit steering angle δlim_R that are set by the sudden increase suppression control may be set to constant values ​​of the first sudden increase suppression angle δu_1 and the second sudden increase suppression angle δu_2, respectively, or may be set according to the following equations 8 and 9.

[0065] δlim_L=α·δa+(1-α)·δlim_L_assist …(8) δlim_R=α·δa+(1-α)·δlim_R_assist …(9)

[0066] In equation 8, "δlim_L_assist" is the left limit steering angle δlim_L set by the steering assist control, and "δlim_R_assist" is the right limit steering angle δlim_R set by the steering assist control. Also, in equations 4 and 5, "α" is a coefficient and is obtained according to equation 10 below.

[0067] α=Treq / Tu …(10)

[0068] In Equation 6, "Treq" is the time that has elapsed since the sudden increase suppression control was started.

[0069] Alternatively, the sudden increase suppression control may be a control in which, when the steering assist torque TQ set by the steering assist control at the time of re-recognition is greater than the actual added torque TQa at the time of re-recognition, the steering assist torque TQ is set using an angle that is reduced by a sudden increase suppression angle δu per unit time from the actual steering angle δa at the time of re-recognition as a limit steering angle δlim, and when the set steering assist torque TQ is applied to the steering operation, the increase in the actual added torque TQa per unit time is equal to or less than the sudden increase suppression value TQu, and when the set steering assist torque TQ is applied to the steering operation, the increase in the actual added torque TQa per unit time is greater than the sudden increase suppression value TQu, and a steering assist torque TQ is applied to the steering operation such that the increase in the actual added torque TQa per unit time becomes the sudden increase suppression value TQu.

[0070] In this way, the sudden increase suppression control is control that increases the actual additional torque TQa by a predetermined sudden increase suppression value TQu per unit time, or control that applies to the steering operation a steering assist torque TQ that is set by using, as a limit steering angle δlim, an angle that is reduced by a predetermined sudden increase suppression angle δu per unit time from the actual steering angle δa at the time when the lane boundary TB becomes recognizable.The vehicle driving assist device 10 is configured to execute the sudden increase suppression control and then execute the steering assist control if the steering assist torque TQ that is set by the steering assist control at the time when the lane boundary TB becomes recognizable after the lane boundary TB becomes recognizable is greater than the actual additional torque TQa at that time.

[0071] When the process proceeds to step S330, the vehicle driving assistance device 10 determines whether or not the completion condition C2 is satisfied. The completion condition C2 is a condition that, when the actual additional torque TQa is increased by the sudden increase suppression value TQu by the sudden increase suppression control, the actual additional torque TQa reaches the steering assist torque TQ set by the steering assist control, and a condition that, when the steering assist torque TQ is set by the sudden increase suppression control using, as the limit steering angle δlim, an angle obtained by decreasing the actual steering angle δa at the time of re-recognition by the sudden increase suppression angle δu per unit time, the limit steering angle δlim set by the sudden increase suppression control reaches the limit steering angle δlim set by the steering assist control.

[0072] If the determination in step S330 is "Yes," the vehicle driving assistance device 10 sets the value of the non-recognition flag X to "0." Next, the vehicle driving assistance device 10 proceeds to step S395 and temporarily ends the processing of this routine. This ends the sudden increase suppression control, and starts the steering assistance control.

[0073] If the vehicle driving assistance device 10 determines "No" in step S320 or "No" in step S330, the process proceeds directly to step S395 and temporarily ends the process of this routine.

[0074] The operation of the vehicle driving assistance device 10 is as described above.

[0075] According to the vehicle driving assistance device 10, when the steering assist control is stopped, the sudden decrease suppression control is executed. If such sudden decrease suppression control is not executed, the steering assist torque TQ applied to the steering operation suddenly becomes zero, which may cause the driver to feel uncomfortable. However, according to the vehicle driving assistance device 10, when the steering assist control is stopped, the sudden decrease suppression control is executed, and the steering assist torque TQ applied to the steering operation is gradually reduced. Therefore, it is possible to prevent the driver from feeling uncomfortable when the steering assist control is stopped.

[0076] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

[0077] For example, the present invention can be applied to a vehicle that can be driven by both manual and automatic driving control. When the present invention is applied to such a vehicle, the present invention is used when a predetermined condition, such as the driver operating the accelerator pedal, is met, the automatic driving control is stopped, and the vehicle is driven manually. [Explanation of symbols]

[0078] 10...vehicle driving assistance device, 20...steering device, 21...power steering device, 22...steering assistance actuator, 33...steering angle sensor, 50...surrounding information detection device, 51...image sensor, 90...ECU, 100...own vehicle, TB...road boundary, TB_L...left road boundary, TB_R...right road boundary

Claims

1. a control device that executes steering assist control to add a steering assist torque that resists the steering operation to the steering operation in order to assist the steering operation performed by an operator of the vehicle; The control device When the vehicle is able to recognize a road boundary that defines the lane in which the vehicle is traveling, the vehicle executes the steering assist control; When the lane boundary cannot be recognized, the steering assist control is stopped. It is structured as follows: The steering assist control is a control that sets a limit steering angle based on the position of the host vehicle relative to the lane boundary, and when the actual steering angle of the host vehicle is larger than the limit steering angle, adds the steering assist torque of a value that is set based on the difference between the limit steering angle and the actual steering angle to the steering operation. In a vehicle driving assistance device, The control device is configured to execute a sudden decrease suppression control when an actual added torque, which is the steering assist torque added to the steering operation at the time when the lane boundary cannot be recognized, is greater than zero, The sudden decrease suppression control is a control that reduces the actual additional torque by a predetermined sudden decrease suppression value per unit time from the actual additional torque at the time when the lane boundary cannot be recognized, or a control that adds the steering assist torque that is set by using, as the limit steering angle, an angle that is increased by a predetermined sudden decrease suppression angle per unit time from the limit steering angle set by the steering assist control at the time when the lane boundary cannot be recognized, to the steering operation. Vehicle driving assistance device.

2. The vehicle driving assistance device according to claim 1, the control device is configured to, when the steering assist torque set by the steering assist control at a time when the lane boundary becomes recognizable after the lane boundary becomes recognizable, be greater than the actual additional torque at that time, perform a sudden increase suppression control and then perform the steering assist control; The sudden increase suppression control is a control to increase the actual added torque by a predetermined sudden increase suppression value per unit time, or a control to add the steering assist torque to the steering operation, which is set using, as the limit steering angle, an angle that is reduced by a predetermined sudden increase suppression angle per unit time from the actual steering angle at the time when the lane boundary can be recognized. Vehicle driving assistance device.

3. A vehicle driving assistance method for performing steering assist control in which a steering assist torque that resists a steering operation is added to the steering operation in order to assist a steering operation performed by an operator of a host vehicle, the method comprising: a step of executing the steering assist control when a road boundary that is a boundary defining a lane in which the host vehicle is traveling can be recognized; When the lane boundary cannot be recognized, stopping the steering assist control. It has The steering assist control is a control that sets a limit steering angle based on the position of the host vehicle relative to the lane boundary, and when the actual steering angle of the host vehicle is larger than the limit steering angle, adds the steering assist torque of a value that is set based on the difference between the limit steering angle and the actual steering angle to the steering operation.

1. A vehicle driving assistance method, The method further includes a step of executing a sudden decrease suppression control when an actual added torque, which is the steering assist torque added to the steering operation at the time when the lane boundary cannot be recognized, is greater than zero, The sudden decrease suppression control is a control that reduces the actual additional torque by a predetermined sudden decrease suppression value per unit time from the actual additional torque at the time when the lane boundary cannot be recognized, or a control that adds the steering assist torque that is set by using, as the limit steering angle, an angle that is increased by a predetermined sudden decrease suppression angle per unit time from the limit steering angle set by the steering assist control at the time when the lane boundary cannot be recognized, to the steering operation. Vehicle driving assistance method.

4. A vehicle driving assistance program that executes steering assistance control to add a steering assistance torque that resists the steering operation to the steering operation in order to assist the steering operation performed by an operator of the vehicle, When the vehicle is able to recognize a road boundary that defines the lane in which the vehicle is traveling, the vehicle executes the steering assist control; When the lane boundary cannot be recognized, the steering assist control is stopped. It is structured as follows: The steering assist control is a control that sets a limit steering angle based on the position of the host vehicle relative to the lane boundary, and when the actual steering angle of the host vehicle is larger than the limit steering angle, adds the steering assist torque of a value that is set based on the difference between the limit steering angle and the actual steering angle to the steering operation. In vehicle driving assistance programs, When the actual added torque, which is the steering assist torque added to the steering operation at the time when the lane boundary cannot be recognized, is greater than zero, a sudden decrease suppression control is executed, The sudden decrease suppression control is a control that reduces the actual additional torque by a predetermined sudden decrease suppression value per unit time from the actual additional torque at the time when the lane boundary cannot be recognized, or a control that adds the steering assist torque that is set by using, as the limit steering angle, an angle that is increased by a predetermined sudden decrease suppression angle per unit time from the limit steering angle set by the steering assist control at the time when the lane boundary cannot be recognized, to the steering operation. Vehicle driving assistance program.

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