Driving assistance device, vehicle control method, and program

Abstract

A driving assistance device, a vehicle control method, and a program reduce the likelihood of a vehicle excessively decelerating due to curve travel control when the vehicle is traveling on a roundabout, and reduce the likelihood of the vehicle being unable to accelerate due to curve travel control when the vehicle exits the roundabout. The driving assistance device is capable of performing roundabout travel control and curve travel control. In the roundabout travel control, the driving state of the vehicle is controlled in such a manner that the vehicle speed, which indicates the speed of the vehicle, coincides with a predetermined target vehicle speed, while the vehicle is traveling on the roundabout. In the curve travel control, at least one of acceleration of the vehicle is suppressed and deceleration of the vehicle is performed, while the vehicle is traveling on a curve. The driving assistance device starts the roundabout travel control when a start condition including detection of the roundabout is satisfied, and suppresses the curve travel control when a predetermined suppression start condition is satisfied after the start of the roundabout travel control.

Description

Technical Field

[0001] This invention relates to a driving assistance device that performs roundabout driving control to control the acceleration and deceleration of a vehicle in a manner that ensures the vehicle speed matches a target speed when traveling on a roundabout. More particularly, it relates to a driving assistance device that also performs cornering driving control to suppress acceleration and decelerate at least one of the following when traveling on a curve. The invention also relates to a vehicle control method in which a computer mounted in the vehicle can perform the aforementioned roundabout driving control and cornering driving control. Furthermore, the invention relates to a program that enables the computer to perform the aforementioned roundabout driving control and cornering driving control. Background Technology

[0002] Previously, there was a known driving assistance device that performed roundabout driving control. For example, the driving assistance device described in Patent Document 1 (hereinafter referred to as "conventional device") performed roundabout driving control to make the vehicle travel in a manner that makes the vehicle speed consistent with a preset target speed when the vehicle is traveling in a roundabout (roundabout intersection).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-088161 Summary of the Invention

[0006] There are known driving assistance devices that perform cornering control by suppressing vehicle acceleration or decelerating the vehicle when it is traveling on a curve. Assuming that conventional devices can also perform cornering control, conventional devices may mistakenly determine that the vehicle is traveling on a curve when it is traveling on a roundabout and perform cornering control.

[0007] If cornering control is performed while the vehicle is traveling on a roundabout, the vehicle may decelerate excessively due to cornering control, and the vehicle speed may become lower than the target speed when traveling on a roundabout.

[0008] Normally, a vehicle will accelerate when exiting a roundabout. However, if cornering control is applied while the vehicle is exiting a roundabout, it may be difficult for the vehicle to accelerate.

[0009] This invention was made to address the aforementioned problems. Specifically, one of the objectives of this invention is to provide a driving assistance device that "reduces the possibility of excessive deceleration of a vehicle due to cornering control when the vehicle is traveling on a roundabout, and further reduces the possibility of difficulty in accelerating the vehicle due to cornering control when the vehicle is exiting a roundabout."

[0010] The driving assistance device of the present invention (hereinafter referred to as "the device of the present invention") is capable of performing roundabout driving control (steps 625 and 1010) and curve driving control (steps 425, 450 and 1010). The roundabout driving control is used to control the driving state of the vehicle in a manner that makes the vehicle speed, which represents the vehicle speed, consistent with a predetermined target vehicle speed when the vehicle is driving on a roundabout. The curve driving control is used to control at least one of the acceleration suppression and deceleration of the vehicle when the vehicle is driving on a curve.

[0011] The driving assistance device is configured such that,

[0012] If the starting condition is met (step 535 is "Yes"), which includes detecting the roundabout in at least the vehicle's direction of travel, the roundabout driving control begins (step 540).

[0013] If the predetermined suppression start condition is met after the start of the roundabout driving control (step 565 is "Yes"), the curve driving control is suppressed (steps 570 and 1005 are "Yes", step 1015).

[0014] If a predetermined suppression initiation condition is met after the start of roundabout driving control, cornering driving control is suppressed. Therefore, if the suppression initiation condition is met while the vehicle is traveling on a roundabout, the possibility of excessive deceleration due to cornering driving control while the vehicle is traveling on a roundabout can be reduced. Furthermore, if the suppression initiation condition is met while the vehicle is exiting a roundabout, the possibility of difficulty in accelerating due to cornering driving control while the vehicle is exiting a roundabout can be reduced.

[0015] In one technical solution of the device of the present invention,

[0016] The driving assistance device is configured to enable the suppression start condition to be met no later than when it is determined that the vehicle has exited the roundabout.

[0017] According to this technical solution, the starting condition for suppressing cornering control is met no later than when the vehicle is determined to have exited the roundabout. Therefore, it can reduce the possibility that the vehicle will have difficulty accelerating due to cornering control when it exits the roundabout.

[0018] In the above technical solutions,

[0019] The driving assistance device is configured to enable the suppression start condition (step 570) when the vehicle enters the roundabout (step 550 is "Yes") and the vehicle speed is consistent with the predetermined suppression start speed (step 565 is "Yes").

[0020] According to this technical solution, it is possible to prevent the vehicle speed from becoming lower than the initial speed of suppression when the vehicle is driving on a roundabout due to curve control.

[0021] In the above technical solutions,

[0022] The driving assistance device is configured to preset the initial suppression speed to the target speed of the roundabout.

[0023] According to this technical solution, it is possible to prevent the vehicle speed from becoming lower than the target speed of the roundabout due to curve control when the vehicle is driving on a roundabout.

[0024] In one technical solution of the device of the present invention,

[0025] The driving assistance device is configured to terminate the suppression of the cornering control (step 675) if a predetermined end time has elapsed since the time point at which the vehicle was determined to have exited the roundabout (step 635 is "Yes", step 645 is "Yes") (step 670 is "Yes").

[0026] Instead of immediately ending the curve control suppression at the point when the vehicle is determined to have exited the roundabout, the suppression ends after an end time has elapsed since the determination point. This reduces the likelihood that the vehicle will struggle to accelerate after exiting the roundabout due to curve control issues arising from ending curve control suppression while the vehicle is still traveling within the roundabout.

[0027] In the above technical solutions,

[0028] The driving assistance device is configured such that,

[0029] Use either the first determination method or the second determination method to determine whether the vehicle has exited the roundabout (steps 630 and 640).

[0030] The end time varies depending on the method used to determine that the vehicle has exited the roundabout (steps 650 and 680).

[0031] Compared to the second determination method, the first determination method determines that the vehicle has exited the roundabout at an earlier time.

[0032] The driving assistance device is configured such that, when the vehicle is determined to have exited the roundabout using the first determination method (step 635 is "Yes"), the end time is extended (step 650) compared to when the vehicle is determined to have exited the roundabout using the second determination method (step 645 is "Yes").

[0033] The end time is set according to different determination methods based on when the vehicle is determined to have exited the roundabout. This reduces the likelihood of the curve control suppression ending while the vehicle is still traveling on the roundabout.

[0034] In the above technical solutions,

[0035] The driving assistance device is configured such that,

[0036] In the first determination method, the determination of whether the vehicle has exited the roundabout is based on the driver's operation of the steering wheel or turn signal lever (steps 800 to 895).

[0037] In the second determination method, the vehicle is determined to have exited the roundabout based on map data showing the location of the roundabout and the vehicle's current location (steps 900 to 995).

[0038] Therefore, it is possible to accurately determine whether a vehicle has exited the roundabout.

[0039] In the vehicle control method of the present invention, the computer mounted on the vehicle is capable of performing roundabout driving control (steps 625 and 1010) and curve driving control (steps 425, 450, and 1010). The roundabout driving control is used to control the driving state of the vehicle in such a way that the vehicle speed, which represents the vehicle speed, is consistent with a predetermined target vehicle speed when the vehicle is driving on a roundabout. The curve driving control is used to control at least one of the acceleration suppression and deceleration of the vehicle when the vehicle is driving on a curve.

[0040] The vehicle control method includes the following steps:

[0041] If the starting condition of detecting the roundabout in at least the vehicle's direction of travel is met (step 510 is "Yes") (step 535 is "Yes"), the computer begins the roundabout driving control step (step 540); and

[0042] If the predetermined suppression start condition is met after the start of the roundabout driving control (step 565 is "Yes"), the computer suppresses the cornering driving control step (steps 570 and 1005 are "Yes", step 1015).

[0043] The program of the present invention enables a computer mounted on a vehicle to perform roundabout driving control (steps 625 and 1010) and curve driving control (steps 425, 450, and 1010). The roundabout driving control is used to control the driving state of the vehicle in a manner that makes the vehicle speed, which represents the vehicle speed, consistent with a predetermined target speed when the vehicle is driving on a roundabout. The curve driving control is used to control at least one of the acceleration suppression and deceleration of the vehicle when the vehicle is driving on a curve.

[0044] The program causes the computer to perform the following steps:

[0045] If the starting condition of detecting the roundabout in at least the vehicle's direction of travel is met (step 510 is "Yes") (step 535 is "Yes"), the roundabout driving control step begins (step 540); and

[0046] If the predetermined suppression start condition is met after the start of the roundabout driving control (step 565 is "Yes"), the step of suppressing the curve driving control is (steps 570 and 1005 are "Yes", step 1015).

[0047] Therefore, if the suppression of the start condition is met while the vehicle is traveling on a roundabout, the possibility of excessive deceleration due to cornering control while the vehicle is traveling on a roundabout can be reduced. Furthermore, if the suppression of the start condition is met while the vehicle is exiting a roundabout, the possibility of difficulty in accelerating due to cornering control while the vehicle is exiting a roundabout can be reduced. Attached Figure Description

[0048] Figure 1 This is a general system configuration diagram of a driving assistance device according to an embodiment of the present invention.

[0049] Figure 2This is a diagram used to illustrate an example of the operation of a driving assistance device according to an embodiment of the present invention.

[0050] Figure 3 yes Figure 1 The flowchart shown is of the curve determination routine executed by the CPU of the ECU.

[0051] Figure 4 yes Figure 1 The flowchart shown is of the cornering control routine executed by the CPU of the ECU.

[0052] Figure 5 yes Figure 1 The flowchart shown is of the roundabout determination routine executed by the CPU of the ECU.

[0053] Figure 6 yes Figure 1 The flowchart shown is a portion of the roundabout driving control routine executed by the CPU of the ECU.

[0054] Figure 7 yes Figure 1 The flowchart shows the remaining part of the roundabout driving control routine executed by the CPU of the ECU.

[0055] Figure 8 yes Figure 1 The flowchart shown is a process for the exit determination subroutine performed by the CPU of the ECU.

[0056] Figure 9 yes Figure 1 The flowchart shown is of the map exit determination subroutine executed by the CPU of the ECU.

[0057] Figure 10 yes Figure 1 The flowchart shown is of the actuator control routine executed by the CPU of the ECU.

[0058] Explanation of reference numerals in the attached figures

[0059] 10: Driving assistance device; 20: ECU; 22: Camera; 34: Map data storage unit; 40: Powertrain actuator; 42: Brake actuator. Detailed Implementation

[0060] The driving assistance device 10 (hereinafter also referred to as "this device 10") according to the embodiments of the present invention is applicable to a vehicle VA and has the following features: Figure 1The components shown are as follows. In this specification, "ECU20" is an electronic control device with a microcomputer as its main component. ECU20 is also referred to as a control unit, controller, or computer. The microcomputer includes a CPU (processor), ROM, RAM, and interfaces (I / F), etc. The functions performed by ECU20 can also be implemented by multiple ECUs.

[0061] Camera 22 acquires image data by capturing images of the scene in front of vehicle VA. ECU 20 obtains the image data from camera 22. GNSS (Global Navigation Satellite System) receiver 24 receives signals from multiple artificial satellites and determines the current position (latitude and longitude) of vehicle VA based on the received signals. ECU 20 obtains the current position of vehicle VA from GNSS receiver 24.

[0062] Acceleration sensor 26 measures the longitudinal acceleration G of vehicle VA. Vehicle speed sensor 28 measures the vehicle speed Vs, which represents the speed of vehicle VA. Steering angle sensor 30 measures the steering angle θ of the steering wheel (not shown) of vehicle VA. Turn signal stalk sensor 32 detects the position of the turn signal stalk. ECU 20 obtains the measured values ​​(detected values) from sensors 26 to 32.

[0063] The storage device 34 includes a map data storage unit 34a. The map data storage unit 34a stores map data that records the location (latitude and longitude) of the roundabout.

[0064] The powertrain actuator 40 alters the driving force generated by the drive unit (e.g., internal combustion engine and / or electric motor) of the vehicle VA. The brake actuator 42 alters the braking force applied to the vehicle VA. The display 44 is, for example, an instrument display. The turn signal 46 is activated (illuminated) according to the operation of the turn signal lever.

[0065] Cornering Control

[0066] An example of cornering control will be explained. In cornering control, ECU 20 decelerates the vehicle speed Vs to a "cornering target speed Vcv suitable for vehicle VA to drive in the corner," and then keeps vehicle VA traveling in the corner at the cornering target speed Vcv. Specifically, ECU 20 sets the cornering target acceleration Gcv to a predetermined deceleration until the vehicle speed Vs matches the cornering target speed Vcv. After the vehicle speed Vs matches the cornering target speed Vcv, the cornering target acceleration Gcv is set to "the acceleration used to maintain the vehicle speed Vs at the cornering target speed Vcv."

[0067] ECU20 begins cornering control when all of the following conditions C1 to C3 are met.

[0068] Condition C1: ECU20 detects a curve.

[0069] Condition C2: The distance Dc from vehicle VA to the entrance of the curve is less than the distance Dcv from the start of the curve.

[0070] Condition C3: Vehicle speed Vs is greater than the target speed Vcv on the curve.

[0071] <Condition C1>

[0072] The ECU 20 detects a white line at a predetermined distance from the front of the vehicle VA based on image data and obtains the curvature of the white line. Furthermore, the white line is the line dividing the lane in which the vehicle VA is traveling. If the curvature of the white line is above a predetermined starting threshold curvature, the ECU 20 determines that a curve exists (i.e., a curve is detected).

[0073] <Condition C2>

[0074] The ECU20 obtains the target vehicle speed Vcv for curves with a larger curvature. The ECU20 obtains the distance that the vehicle VA travels until its speed Vs at the entrance of the curve matches the target vehicle speed Vcv, under the assumption of deceleration with a predetermined negative acceleration (i.e., deceleration). This distance is taken as the curve start distance Dcv.

[0075] Furthermore, in cornering control, ECU20 suppresses the acceleration of vehicle VA in a manner that prevents the acceleration G of vehicle VA from exceeding a predetermined positive maximum acceleration Gmax.

[0076] <Roundabout driving control>

[0077] An example of roundabout driving control is explained. In roundabout driving control, ECU 20 decelerates the vehicle speed Vs to a predetermined roundabout target speed Vra, causing the vehicle VA to travel at the roundabout target speed Vra. Specifically, ECU 20 sets the roundabout target acceleration Gra to a predetermined deceleration until the vehicle speed Vs matches the roundabout target speed Vra. After the vehicle speed Vs matches the roundabout target speed Vra, the roundabout target acceleration Gra is set to "the acceleration used to maintain the vehicle speed Vs at the roundabout target speed Vra".

[0078] ECU20 begins roundabout driving control when all of the following conditions R1 to R3 are met.

[0079] Condition R1: ECU20 detects a roundabout.

[0080] Condition R2: The distance Dr from vehicle VA to the entrance of the roundabout is less than or equal to "the starting distance Dra1 is set longer as the vehicle speed Vs increases".

[0081] Condition R3: Vehicle speed Vs is greater than the target vehicle speed Vra at the roundabout.

[0082] <Condition R1>

[0083] ECU20 obtains the current position of vehicle VA from GNSS receiver 24. Referring to map data, ECU20 determines whether a roundabout exists within a predetermined distance from the current position of vehicle VA in its direction of travel. If a roundabout exists, ECU20 detects it.

[0084] <Condition R2>

[0085] Distance Dr is obtained based on the current position of vehicle VA in the map data and the position of roundabout.

[0086] <Job Summary>

[0087] When a predetermined suppression start condition is met after the start of roundabout driving control, this device 10 suppresses cornering driving control. Specifically, when the suppression start condition is met, even if the target cornering acceleration Gcv is obtained, this device 10 sets the target cornering acceleration Gcv to an invalid value. Therefore, when the suppression start condition is met, cornering driving control is not actually performed. Thus, even if cornering driving control is performed while vehicle VA is traveling on a roundabout, the possibility that the vehicle speed Vs will become lower than the target roundabout speed Vra due to cornering driving control can be reduced (i.e., the possibility that vehicle VA will decelerate excessively due to cornering driving control). Furthermore, the possibility that vehicle VA will have difficulty accelerating due to cornering driving control when exiting the roundabout can be reduced.

[0088] The suppression start condition is met when vehicle VA arrives at the roundabout and its speed Vs falls below a predetermined suppression start speed. In this embodiment, the suppression start speed is set to the roundabout target speed Vra.

[0089] (Work example)

[0090] Reference Figure 2The operation of ECU20 is explained below. ECU20 refers to map data to determine whether a roundabout exists within a predetermined distance from the current position of vehicle VA in its direction of travel. If a roundabout exists, ECU20 obtains a starting distance Dra1 based on the vehicle speed Vs. ECU20 then adds the distance Dp traveled by vehicle VA at its current speed Vs over a predetermined time to the starting distance Dra1 as the displayed starting distance Dra2.

[0091] At time t1, the "distance Dr from vehicle VA to the entrance of the roundabout" becomes less than or equal to the starting display distance Dra2. In this case, ECU 20 displays the roundabout display element on display 44 indicating that vehicle VA is traveling on the roundabout.

[0092] At time t2, the distance Dr becomes less than the initial distance Dra1. In this case, ECU20 initiates roundabout driving control, causing vehicle VA to begin decelerating at a predetermined deceleration.

[0093] Subsequently, vehicle VA decelerates while entering the roundabout. At time t3, vehicle speed Vs matches the target speed Vra of the roundabout. In this case, since the aforementioned suppression initiation condition is met, ECU 20 begins to suppress cornering control. Because the curvature of the white line near the entrance of the roundabout may exceed the threshold curvature, ECU 20 may incorrectly identify the roundabout as a curve. As a result, ECU 20 may incorrectly execute cornering control while vehicle VA is traveling on the roundabout. Even if cornering control is incorrectly executed, it will be suppressed, thus reducing the possibility of excessive deceleration of vehicle VA and the possibility of vehicle VA failing to accelerate.

[0094] Subsequently, at time t4, ECU20 determines that vehicle VA has exited the roundabout. In this case, ECU20 terminates roundabout driving control. Furthermore, the determination of whether vehicle VA has exited the roundabout includes operation exit determination (method 1) and map exit determination (method 2).

[0095] In determining whether a vehicle has exited the roundabout, ECU 20 determines that vehicle VA has exited the roundabout if at least one of the following conditions is met: a first operation exit condition where the magnitude of the steering angle θ (|θ|) is greater than or equal to the threshold angle θth and the steering direction is opposite to the steering direction when driving through the roundabout; and a second operation exit condition where the turn signal lever has been operated. When vehicle VA has exited the roundabout, there is a high probability that the driver has significantly steered the steering wheel in the direction opposite to the steering direction when driving through the roundabout. Furthermore, when vehicle VA has exited the roundabout, there is a high probability that the driver has operated the turn signal lever, activating turn signal 46. Therefore, ECU 20 determines that vehicle VA has exited the roundabout if at least one of the first and second operation exit conditions is met.

[0096] In the map exit determination process, if the ECU20 determines, based on map data, that vehicle VA's current position is outside the roundabout, it determines that vehicle VA has exited the roundabout. Even if vehicle VA exits the roundabout without the driver significantly steering in the opposite direction to the steering direction used when driving through the roundabout and without activating the turn signal stalk, the ECU20 can still determine that vehicle VA has exited the roundabout through the map exit determination process.

[0097] If ECU20 determines that vehicle VA has exited the roundabout based on the operation exit judgment, it sets the end time Tth to time 1 T1. On the other hand, if ECU20 determines that vehicle VA has exited the roundabout based on the map exit judgment, it sets the end time Tth to time 2 T2. Time 1 T1 is set to a value greater than time 2 T2.

[0098] At time t5, the elapsed time T from the time point at which vehicle VA was determined to have exited the roundabout becomes the end time Tth. In this case, ECU20 terminates the suppression of cornering control. Normally, when vehicle VA is within the roundabout, the driver will perform steering operations or turn signal activation to allow vehicle VA to exit the roundabout. Therefore, the operation-based exit determination usually determines that vehicle VA has exited the roundabout at an earlier timing than the map exit determination. By setting the first time T1 to a value larger than the second time T2, the likelihood of terminating the suppression of cornering control after vehicle VA has reliably exited the roundabout is increased. This is because if the suppression of cornering control were terminated before vehicle VA exited the roundabout, the cornering control would make it difficult for vehicle VA to accelerate when exiting the roundabout.

[0099] (Specific tasks)

[0100] The CPU of ECU20 executes at predetermined intervals. Figures 3 to 6 as well as Figure 10 The routines are illustrated in the flowchart.

[0101] <Curve Detection Routine>

[0102] When the appropriate time arrives, the CPU will... Figure 3 Processing begins at step 300 and proceeds to step 305. In step 305, the CPU determines whether the cornering indicator Xcv is "0". The cornering indicator Xcv is set to "1" when cornering control is executed, and set to "0" when cornering control is not executed. The cornering indicator Xcv is set to "0" in the initialization routine. The initialization routine is executed by the CPU when the ignition key switch (not shown) of the vehicle VA changes from the off position to the on position.

[0103] If the curve flag Xcv is "0", the CPU determines "yes" in step 305 and proceeds to step 310. In step 310, the CPU determines whether a curve has been detected as described above.

[0104] If no curve is detected, the CPU determines "No" in step 310 and proceeds to step 395. In step 395, the CPU temporarily terminates the current routine.

[0105] On the other hand, if a curve is detected, the CPU determines "yes" in step 310 and executes steps 315 and 320.

[0106] Step 315: The CPU obtains the starting distance Dcv of the curve based on the target speed Vcv of the curve corresponding to the curvature of the white line and the current speed Vs.

[0107] Step 320: The CPU determines whether the distance to Dc is less than the starting distance to the curve Dcv and whether the vehicle speed Vs is greater than the target speed Vcv for the curve.

[0108] If the distance to Dc is greater than the starting distance to the curve Dcv, or the vehicle speed Vs is less than or equal to the target speed Vcv for the curve, the CPU determines "No" in step 320 and proceeds to step 395. Conversely, if the distance to Dc is less than or equal to the starting distance to the curve Dcv and the vehicle speed Vs is greater than or equal to the target speed Vcv for the curve, the CPU determines "Yes" in step 320 and proceeds to step 325. In step 325, the CPU sets the curve flag Xcv to "1" and proceeds to step 395.

[0109] If the curve marker Xcv is "1" when processing proceeds to step 305, the CPU determines "No" in step 305 and proceeds to step 330. In step 330, the CPU determines whether vehicle VA has exited the curve. Specifically, the CPU determines that vehicle VA has exited the curve if the curvature of the white line is below the "end threshold curvature which is smaller than the start threshold curvature".

[0110] If vehicle VA has not exited the curve, the CPU determines "No" in step 330 and proceeds to step 395. Conversely, if vehicle VA has exited the curve, the CPU determines "Yes" in step 330 and proceeds to step 335. In step 335, the CPU sets the curve flag Xcv to "0" and proceeds to step 395.

[0111] <Cornering Control Routine>

[0112] When the appropriate time arrives, the CPU will... Figure 4 The process begins at step 400 and proceeds to step 405. In step 405, the CPU determines whether the curve flag Xcv is "1".

[0113] If the curve flag Xcv is "0", the CPU determines "No" in step 405 and proceeds to step 495. In step 495, the CPU temporarily terminates the current routine. If the curve flag Xcv is "1", the CPU determines "Yes" in step 405 and proceeds to step 410.

[0114] In step 410, the CPU determines whether the display prohibition flag Xkin is "0". When performing cornering control, the CPU displays a cornering display element on the display 44 indicating that the vehicle VA is cornering. The display prohibition flag Xkin is set to "1" when the display of the cornering display element is prohibited, and set to "0" when the display of the cornering display element is permitted. The display prohibition flag Xkin is set to "0" in the initialization routine.

[0115] If the display prohibition flag Xkin is "0", the CPU determines "yes" in step 410 and executes steps 415 to 430.

[0116] Step 415: The CPU displays the curve display elements on the monitor 44.

[0117] Step 420: The CPU obtains the target speed Vcv for the curve, which corresponds to the curvature of the curve.

[0118] Step 425: The CPU obtains the target acceleration Gcv for the curve to make the vehicle speed Vs match the target vehicle speed Vcv in the curve.

[0119] Step 430: The CPU determines whether the accelerator pedal (not shown) of the vehicle's VA has been operated.

[0120] If the accelerator pedal is not operated, the CPU determines "no" in step 430 and proceeds to step 495.

[0121] If the accelerator pedal is operated, the CPU determines "yes" in step 430 and executes steps 435 and 440.

[0122] Step 435: The CPU obtains the operating acceleration Gman based on the amount of accelerator pedal depressor.

[0123] Step 440: The CPU determines whether the operating acceleration Gman is greater than or equal to the preset maximum acceleration Gmax.

[0124] If the operating acceleration Gman is less than the maximum acceleration Gmax, the CPU determines "No" in step 440 and proceeds to step 445. In step 445, the CPU sets the cornering target acceleration Gcv to the operating acceleration Gman. Then, the process proceeds to step 495.

[0125] If the operating acceleration Gman is greater than or equal to the maximum acceleration Gmax, the CPU determines "yes" in step 440 and sets the cornering target acceleration Gcv to the maximum acceleration Gmax. Then, processing proceeds to step 495. Therefore, when performing cornering control, the possibility of acceleration G exceeding the maximum acceleration Gmax due to accelerator pedal operation is suppressed.

[0126] If the prohibition flag Xkin is displayed as "1" when processing proceeds to step 410, the CPU determines "No" in step 410 and proceeds to step 420. As a result, the curve display element is not displayed on the display 44.

[0127] <Roundabout detection routine>

[0128] When the appropriate time arrives, the CPU will... Figure 5 The process begins at step 500 and proceeds to step 505. In step 505, the CPU determines whether the roundabout sign Xra is "0".

[0129] The roundabout sign Xra is set to "1" when roundabout driving control is enabled and set to "0" when roundabout driving control is not enabled. The roundabout sign Xra is set to "0" in the initialization routine.

[0130] If the roundabout flag Xra is "0", the CPU determines "yes" in step 505 and proceeds to step 510. In step 510, the CPU determines whether a roundabout has been detected (refer to condition R1 above).

[0131] If no roundabout is detected, the CPU determines "No" in step 510 and proceeds to step 595. In step 595, the CPU temporarily terminates the current routine.

[0132] If a roundabout is detected, the CPU determines "yes" in step 510 and executes steps 515 to 525.

[0133] Step 515: The CPU obtains the starting distance Dra1 based on the vehicle speed Vs.

[0134] Step 520: The CPU obtains the starting distance Dra2.

[0135] Step 525: The CPU determines whether the distance Dr is below the display start distance Dra2.

[0136] If the distance Dr is greater than the display start distance Dra2, the CPU determines "No" in step 525 and proceeds to step 595. If the distance Dr is less than or equal to the display start distance Dra2, the CPU determines "Yes" in step 525 and executes steps 530 and 535.

[0137] Step 530: The CPU sets the roundabout display flag Xdsp to "1".

[0138] The roundabout display flag Xdsp is set to "1" when the roundabout display element is displayed, and to "0" when the roundabout display element is not displayed. The roundabout display flag Xdsp is set to "0" in the initialization routine.

[0139] Step 535: The CPU determines whether the distance Dr is less than the starting distance Dra1 and whether the vehicle speed Vs is greater than the target vehicle speed Vra at the roundabout.

[0140] If the distance Dr is greater than the starting distance Dra1 or the vehicle speed Vs is less than or equal to the target vehicle speed Vra at the roundabout, the CPU determines "No" in step 535 and proceeds to step 595. If the distance Dr is less than or equal to the starting distance Dra1 and the vehicle speed Vs is greater than or equal to the target vehicle speed Vra at the roundabout, the CPU determines "Yes" in step 535 and executes steps 540 and 545.

[0141] Step 540: The CPU sets the roundabout sign Xra to "1".

[0142] Step 545: The CPU determines whether the display disable flag Xkin is "0".

[0143] If the prohibition sign Xkin is displayed as "0", the CPU determines "yes" in step 545 and proceeds to step 550. In step 550, the CPU refers to map data to determine whether vehicle VA has reached the roundabout.

[0144] If vehicle VA does not reach the roundabout, the CPU determines "no" in step 550 and proceeds to step 595.

[0145] If vehicle VA reaches the roundabout, the CPU determines "yes" in step 550 and proceeds to step 555. In step 555, the CPU sets the prohibition sign Xkin to "1". Then, the process proceeds to step 595.

[0146] If the roundabout sign Xra is "1" when proceeding to step 505, the CPU determines "No" in step 505 and proceeds to step 545. If the prohibition sign Xkin is "1" when proceeding to step 545 (i.e., when vehicle VA has arrived at the roundabout), the CPU determines "No" in step 545 and proceeds to step 560.

[0147] In step 560, the CPU determines whether the suppression flag Xyok is "0". The suppression flag Xyok is set to "1" when cornering control is suppressed, and set to "0" when cornering control is not suppressed. The suppression flag Xyok is set to "0" in the initialization routine.

[0148] If the suppression flag Xyok is "0", the CPU determines "yes" in step 560 and proceeds to step 565. In step 565, the CPU determines whether the vehicle speed Vs is consistent with the target vehicle speed Vra at the roundabout.

[0149] If the vehicle speed Vs is greater than the target vehicle speed Vra at the roundabout, the CPU determines "No" in step 565 and proceeds to step 595. If the vehicle speed Vs is the same as the target vehicle speed Vra at the roundabout, the CPU determines that the suppression start condition is met. In this case, the CPU determines "Yes" in step 565 and proceeds to step 570.

[0150] In step 570, the CPU sets the suppression flag Xyok to "1". Then, processing proceeds to step 595.

[0151] If the suppression flag Xyok is "1" when processing proceeds to step 560, the CPU determines "No" in step 560 and proceeds to step 595.

[0152] <Roundabout Traffic Control Routine>

[0153] When the appropriate time arrives, the CPU will... Figure 6 The process begins at step 600 and proceeds to step 605. In step 605, the CPU determines whether the roundabout display flag Xdsp is "1".

[0154] If the Xdsp indicator at the roundabout is "0", the CPU determines "No" in step 605 and proceeds to the next step. Figure 7 Step 610 is shown. In step 610, the CPU determines whether the exit flag Xexi is "1". The exit flag Xexi is set to "1" when vehicle VA exits the roundabout. The exit flag Xexi is set to "0" when an end time Tth has elapsed since the determination time that vehicle VA has exited the roundabout, thus ending the suppression of cornering control. The exit flag Xexi is set to "0" in the initialization routine.

[0155] If the exit flag Xexi is "0", the CPU determines "No" in step 610 and proceeds to the next step. Figure 6 The step shown is 695. In step 695, the CPU temporarily terminates the current routine.

[0156] If the roundabout display flag Xdsp is "1" when processing proceeds to step 605, the CPU determines "yes" in step 605 and executes steps 615 and 620.

[0157] Step 615: The CPU displays the roundabout display elements on the display 44.

[0158] Step 620: The CPU determines whether the roundabout sign Xra is "1".

[0159] If the roundabout sign Xra is "0", the CPU determines "No" in step 620 and proceeds to the next step. Figure 7 Step 610 is shown. When the roundabout sign Xra is "1", the CPU... Figure 6 If the determination in step 620 is "yes", then proceed to steps 625 to 635.

[0160] Step 625: The CPU obtains the roundabout target acceleration Gra to make the vehicle speed Vs match the roundabout target vehicle speed Vra.

[0161] Step 630: CPU execution Figure 8 The operation exit decision subroutine is shown below. The operation exit decision subroutine will be described later.

[0162] Step 635: The CPU determines whether the operation exit determination subroutine has determined that vehicle VA has exited the roundabout.

[0163] If the exit determination subroutine does not determine that vehicle VA has exited the roundabout, the CPU determines "no" in step 635 and executes steps 640 and 645.

[0164] Step 640: CPU execution Figure 9 The map exit decision subroutine is shown below. The map exit decision subroutine will be described later.

[0165] Step 645: The CPU determines whether the map exit determination subroutine has determined that vehicle VA has exited the roundabout.

[0166] If the CPU determines that vehicle VA has not exited the roundabout in the map exit determination subroutine, it will determine "no" in step 645 and proceed to step 695.

[0167] If, during the process proceeding to step 635, the CPU determines in the operation exit determination subroutine that vehicle VA has exited the roundabout that it is "yes" and executes steps 650 to 660. Afterwards, the process proceeds to step 695.

[0168] Step 650: The CPU sets the end time Tth to the first time T1.

[0169] Step 655: The CPU sets the exit flag Xexi to "1" and the elapsed time T to "0".

[0170] The elapsed time T is the elapsed time from the time point determined above.

[0171] Step 660: The CPU sets the roundabout sign Xra to "0" and the roundabout display sign Xdsp to "0".

[0172] Then, the process proceeds to step 695.

[0173] In processing the advance to Figure 7 When the exit flag Xexi is "1" in step 610, the CPU determines "yes" in step 610 and executes steps 665 and 670.

[0174] Step 665: The CPU adds "the execution cycle Tp of this routine" to the elapsed time T.

[0175] Step 670: The CPU determines whether the elapsed time T is greater than or equal to the end time Tth.

[0176] If the elapsed time T is less than the end time Tth, the CPU determines "No" in step 670 and proceeds to the next step. Figure 6 Step 695 is shown. On the other hand, when the elapsed time T is greater than or equal to the end time Tth, the CPU... Figure 7 If the determination in step 670 is "yes", the process proceeds to step 675. In step 675, the CPU sets the suppression flag Xyok, the display disable flag Xkin, and the exit flag Xexi to "0", and sets the elapsed time T to "0".

[0177] After that, proceed with the process to... Figure 6 Step 695 is shown.

[0178] In processing the advance to Figure 6 In step 645, if the map exit determination subroutine determines that vehicle VA has exited the roundabout, the CPU determines "yes" in step 645 and proceeds to step 680. In step 680, the CPU sets the end time Tth to "the second time T2, which is smaller than the first time T1". Then, the process proceeds to step 655.

[0179] <Operation Exit Determination Subroutine>

[0180] In processing the advance to Figure 6 In step 630 as shown, the CPU starts from... Figure 8 The process begins at step 800 and proceeds to step 805. In step 805, the CPU determines whether the magnitude of the steering angle θ (|θ|) is greater than or equal to the threshold angle θth.

[0181] If the magnitude of the steering angle θ (|θ|) is greater than or equal to the threshold angle θth, the CPU determines "yes" in step 805 and proceeds to step 810. In step 810, the CPU determines whether the steering direction at the current time point is opposite to the "roundabout steering direction representing the steering direction of vehicle VA during its travel on the roundabout".

[0182] The CPU obtains the steering direction during the period when the roundabout marker is "1" after a predetermined time interval. The CPU determines the steering direction with the longest duration during that period as the roundabout steering direction. Furthermore, the steering direction can be either right or left.

[0183] If the steering direction at the current time point is opposite to the steering direction at the roundabout, the first operation exit condition is met. In this case, the CPU determines "yes" in step 810 and proceeds to step 815. In step 815, the CPU determines that vehicle VA has exited the roundabout, and in step 895, the CPU temporarily terminates this routine. Afterwards, the process proceeds to... Figure 6 Step 635 is shown.

[0184] In processing the advance to Figure 8 If, in step 805, the steering angle θ (|θ|) is less than the threshold angle θth, the CPU determines "No" in step 805 and proceeds to step 820. In step 820, the CPU determines whether the turn signal lever has been activated.

[0185] If the turn signal lever is activated, the second operation exit condition is met. In this case, the CPU determines "yes" in step 820 and proceeds to step 815. Conversely, if the turn signal lever is not activated, neither the first nor the second operation exit condition is met. In this case, the CPU determines "no" in step 820 and proceeds to step 825. In step 825, the CPU determines that vehicle VA has not exited the roundabout. Then, the process proceeds to step 895.

[0186] If the steering direction at the current time point is the same as the steering direction at the roundabout when processing to step 810, the CPU determines "no" in step 810 and proceeds to step 820.

[0187] <Map Exit Decision Subroutine>

[0188] In processing the advance to Figure 6 In step 640 as shown, the CPU starts from... Figure 9 The process begins at step 900, followed by steps 905 and 910.

[0189] Step 905: The CPU obtains the current location of the vehicle VA from the GNSS receiver 24.

[0190] Step 910: The CPU refers to the map data to determine whether the current position of vehicle VA is located outside the roundabout.

[0191] If vehicle VA is currently located outside the roundabout, the CPU determines "yes" in step 910 and proceeds to step 915. In step 915, the CPU determines that vehicle VA has exited the roundabout, and in step 995, the CPU temporarily terminates this routine. Then, the process proceeds to... Figure 6Step 645 is shown.

[0192] If vehicle VA is currently located inside the roundabout, the CPU determines "No" in step 910 and proceeds to step 920. In step 920, the CPU determines that vehicle VA has not exited the roundabout. Then, the process proceeds to step 995.

[0193] <Actuator Control Routine>

[0194] When the appropriate time arrives, the CPU will... Figure 10 The process begins at step 1000 and proceeds to step 1005. In step 1005, the CPU determines whether the suppression flag Xyok is "1".

[0195] If the suppression flag Xyok is "0", the CPU determines "No" in step 1005 and proceeds to step 1010. In step 1010, the CPU selects the minimum acceleration between the target acceleration Gcv for the curve and the target acceleration Gra for the roundabout as the minimum acceleration Gmin, and controls the powertrain actuator 40 and the brake actuator 42 in a manner that makes the acceleration G consistent with the minimum acceleration Gmin. After that, the process proceeds to step 1095, and the CPU temporarily terminates this routine.

[0196] If the suppression flag Xyok is "1", the CPU determines "yes" in step 1005 and proceeds to step 1015. In step 1015, the CPU disables the cornering target acceleration Gcv. Specifically, the CPU sets the cornering target acceleration Gcv to an invalid value. Then, the process proceeds to step 1010. In this case, in step 1010, the disabled cornering target acceleration Gcv will not be selected as the minimum acceleration Gmin. Therefore, in step 1010, the CPU controls the powertrain actuator 40 and the brake actuator 42 in a manner that makes the acceleration G consistent with the roundabout target acceleration Gra. Then, the process proceeds to step 1095.

[0197] In this embodiment, cornering control is suppressed from the time the suppression start condition is met until the end time Tth has elapsed since the determination that vehicle VA has exited the roundabout via either the operation exit determination or the map exit determination. This reduces the likelihood of excessive deceleration of vehicle VA when it is traveling on the roundabout due to cornering control causing its speed Vs to be lower than the roundabout target speed Vra. Furthermore, it reduces the likelihood of vehicle VA being unable to accelerate due to cornering control when it exits the roundabout.

[0198] The present invention is not limited to the above-described embodiments, and various modifications of the present invention can be adopted.

[0199] <First Variation>

[0200] In the above implementation, the suppression start condition is established when vehicle VA arrives at the roundabout and its speed Vs is consistent with the target speed Vra of the roundabout, but the suppression start condition can be established no later than when it is determined that vehicle VA has exited the roundabout.

[0201] <Second Variation>

[0202] In cornering control, the CPU can execute at least one of the following: control to suppress the acceleration of vehicle VA in a way that prevents the acceleration G of vehicle VA from exceeding the predetermined positive maximum acceleration Gmax, and control to decelerate the speed Vs of vehicle VA to the target speed Vcv of the corner.

[0203] <3rd Variation>

[0204] The starting condition for roundabout driving control must include at least the condition that the ECU20 detects a roundabout (condition R1 above). In addition, the starting distance Dra1 used in condition R2 above in the starting condition for roundabout driving control can also be a constant value independent of the vehicle speed Vs.

[0205] <4th Variation>

[0206] The suppression start speed used for the suppression start condition can be set to a value different from the roundabout target speed Vra (for example, a value larger than the roundabout target speed Vra). In this case, the suppression start condition is met when vehicle VA arrives at the roundabout and its speed Vs becomes below the suppression start speed.

[0207] <5th Variation>

[0208] The CPU can also detect roundabouts based on image data. For example, if the image data contains a roundabout marker, the CPU can detect the roundabout. Furthermore, the CPU can also obtain the distance Dr based on the image data.

[0209] <Sixth Variation>

[0210] In the above implementation, when the CPU determines that vehicle VA has exited the roundabout, it sets the roundabout display flag Xdsp to "0" (refer to...). Figure 6Step 660 (as shown) ends the display of the roundabout display element, but the timing for ending the display of the roundabout display element is not limited to this. For example, the CPU may also end the display of the roundabout display element at a time point when the end time Tth (the time point when the suppression of cornering control ends) has elapsed since the above-mentioned determination time point.

[0211] This device 10 can be applied to vehicles such as engine-powered cars, hybrid vehicles, plug-in hybrid vehicles, fuel cell vehicles, and electric vehicles. Cornering control and roundabout driving control are types of automated driving systems used to assist drivers.

[0212] The present invention can also be understood as a non-transient storage medium that stores a program for implementing the functions of the device 10 and is readable by a computer.

Claims

1. A driving assistance device, The driving assistance device is capable of performing roundabout driving control and cornering driving control. The roundabout driving control is used to control the vehicle's driving state in a manner that ensures the vehicle's speed, as indicated by its speed, matches a predetermined target speed when the vehicle is traveling on a roundabout. The cornering driving control is used to control at least one of the following when the vehicle is traveling on a curve: suppressing acceleration and decelerating. The driving assistance device is configured such that, If the starting condition, which includes detecting the roundabout in at least the vehicle's direction of travel, is met, then roundabout driving control begins. If a predetermined suppression start condition is met after the start of the roundabout driving control, the cornering driving control is suppressed.

2. The driving assistance device according to claim 1, The driving assistance device is configured to enable the suppression start condition to be met no later than when it is determined that the vehicle has exited the roundabout.

3. The driving assistance device according to claim 2, The driving assistance device is configured to enable the suppression start condition when the vehicle enters the roundabout and the vehicle speed is below a predetermined suppression start speed.

4. The driving assistance device according to claim 3, The driving assistance device is configured to preset the initial suppression speed to the target speed of the roundabout.

5. The driving assistance device according to claim 1, The driving assistance device is configured to terminate the suppression of cornering control if a predetermined end time has elapsed since the point at which the vehicle was determined to have exited the roundabout.

6. The driving assistance device according to claim 5, The driving assistance device is configured such that, Use either the first determination method or the second determination method to determine whether the vehicle has exited the roundabout. The end time varies depending on the method used to determine whether the vehicle has exited the roundabout.

7. The driving assistance device according to claim 6, Compared to the second determination method, the first determination method determines that the vehicle has exited the roundabout at an earlier time. The driving assistance device is configured to extend the end time when the vehicle has exited the roundabout using the first determination method, compared to when the vehicle has exited the roundabout using the second determination method.

8. The driving assistance device according to claim 7, The driving assistance device is configured such that, In the first determination method, whether the vehicle has exited the roundabout is determined based on the driver's operation of the steering wheel or turn signal lever. In the second determination method, it is determined whether the vehicle has exited the roundabout based on map data showing the location of the roundabout and the vehicle's current location.

9. A vehicle control method, In the vehicle control method, the computer mounted on the vehicle is capable of performing roundabout driving control and curve driving control. The roundabout driving control is used to control the vehicle's driving state in a manner that ensures the vehicle speed, representing the vehicle's speed, matches a predetermined target speed when the vehicle is driving on a roundabout. The curve driving control is used to control at least one of the following when the vehicle is driving on a curve: suppressing acceleration and decelerating. The vehicle control method includes the following steps: If the starting condition, which includes at least detecting the roundabout in the vehicle's direction of travel, is met, the computer begins the roundabout driving control steps; and The computer suppresses the cornering control step when a predetermined suppression initiation condition is met after the start of the roundabout driving control.

10. A program, The system enables a vehicle-mounted computer to perform roundabout driving control and cornering driving control. The roundabout driving control is used to control the vehicle's driving state while it is driving on a roundabout, such that the vehicle speed, representing the vehicle's speed, matches a predetermined target speed. The cornering driving control is used to control at least one of the following while it is driving on a curve: suppressing acceleration and decelerating the vehicle. The program causes the computer to perform the following steps: The step of initiating roundabout driving control when the starting condition, which includes at least the condition that the roundabout is detected in the direction of travel of the vehicle, is met; and The step of suppressing the cornering driving control is performed when a predetermined suppression start condition is met after the start of the roundabout driving control.

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