Vehicle driver assistance systems

Abstract

The present invention provides a driving assistance system for a vehicle, which prevents the vehicle from immediately switching to a manual driving mode even when the driver's steering torque is detected in an automatic driving in a first driving assistance mode conditioned on the grip of a steering wheel. Even when a steering wheel touch sensor (421, 42r) provided on a rim (2a) of a steering wheel (2) and provided at a left or right position where the driver normally grips the vehicle is turned on (S31) and the driver's steering torque Tst is detected by a steering torque sensor (44), if the steering torque Tst is below a steering override determination threshold value Tsto, it is determined to be a simple false contact (false detection), and the first driving assistance mode is continued, thereby preventing the vehicle from immediately switching to a manual driving mode.

Description

Technical Field

[0001] The present invention relates to a driving assistance system for a vehicle having at least a first driving assistance mode for performing automatic driving under the condition that the driver holds the steering wheel and a second driving assistance mode for performing automatic driving without the condition that the driver holds the steering wheel as driving modes. Background Art

[0002] In recent years, various driving assistance systems based on automatic driving have been proposed for reducing the burden on drivers and enabling comfortable and safe driving, and some of them have already been put into practical use.

[0003] The driving modes of this driving assistance system include: a driving assistance mode in which, when it is determined that it is difficult to continue automatic driving, the driver is made to wait in advance so that the driver can take over the operation (hereinafter referred to as the "first driving assistance mode") and a driving assistance mode in which the driver does not need to take over the driving (hereinafter referred to as the "second driving assistance mode").

[0004] The first driving assistance mode is a mode in which the vehicle follows the preceding vehicle along the lane by using the existing lane keeping (ALK) control and cruise control with automatic distance keeping control (ACC: Adaptive Cruise Control) system, and when the preceding vehicle is not detected, the vehicle drives at a set speed. Therefore, although the first driving assistance mode does not require the driver to actively operate the steering wheel, it is conditioned on the driver holding the steering wheel in advance (hereinafter, this state is sometimes referred to as "holding the steering wheel") and being able to take over the driving at any time.

[0005] On the other hand, the second driving assistance mode always compares the consistency of the road shape on the map where the vehicle is traveling detected by the map locator and the road shape of the lane actually traveling detected by the camera unit, etc. When the consistency is high, the driver is not required to hold the steering wheel, but the control system is the driving subject to continue the automatic driving. And only when it is judged that it is difficult to continue the automatic driving, the driver is required to hold the steering wheel and transfer to the first driving mode, or the automatic retreat mode is executed. In addition, the automatic retreat mode allows the vehicle to travel in the driving lane at the statutory or specified minimum speed. Alternatively, the vehicle is guided to a safe place such as a roadside area and stopped.

[0006] Furthermore, when the vehicle is traveling in the second driving assistance mode, if the driver holds the steering wheel, the driving assistance system determines that it is the driver's intention and switches the driving mode to the first driving assistance mode. In addition, if the driving assistance system detects steering intervention (steering override) by the driver, the driving mode will of course interrupt the automatic driving and switch to the manual driving mode. However, if it is an erroneous operation, it is contrary to the intention of the driver who wants to continue the automatic driving, which has the disadvantage of making the driver feel uncomfortable.

[0007] As a technology for detecting the driver's grip on the steering wheel, for example, Patent Document 1 (Japanese Patent Gazette No. 5009473) discloses a technology for providing a touch sensor (pressure sensor, capacitance sensor, electrode pair, etc.) on the rim of the steering wheel to detect the driver's grip on the steering wheel and the grip position.

[0008] In addition, as a technology for detecting driver's steering intervention, Patent Document 2 (Japanese Patent Gazette No. 4435519) discloses a technology that compares the steering torque detected by a torque sensor with a threshold set based on the vehicle speed, and when the steering torque is above the threshold, it is determined that the driver has intervened in steering, and the automatic steering is canceled.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent No. 5009473

[0012] Patent Document 2: Japanese Patent No. 4435519 Summary of the invention

[0013] Technical issues

[0014] In the technology disclosed in Patent Document 2 mentioned above, the steering torque is detected by using a torque sensor to detect the driver's intention of steering intervention, thereby preventing erroneous determination.

[0015] However, since the driver is not required to hold the steering wheel when driving in the second driving assistance mode, the driver is likely to change his posture such as turning back during driving. In this case, it is conceivable that a part of the body presses the steering wheel to generate steering torque in an unexpected direction. In this case, it is determined that the steering intervention is contrary to the driver's intention. For example, if the driver is notified of "transfer to manual driving mode", the driver may feel uncomfortable.

[0016] Furthermore, even when driving in the first driving assistance mode requiring the driver to hold the steering wheel, the torque sensor may detect steering torque due to external disturbances such as uneven road conditions and / or crosswinds and misjudge it as steering intervention (steering override) by the driver.

[0017] In view of the above situation, the present invention aims to provide a driving assistance system for a vehicle, which, in automatic driving in a second driving assistance mode that is not conditional on the control of the steering wheel, or in a first driving assistance mode that is conditional on the control of the steering wheel, prevents the vehicle from immediately switching to a manual driving mode even when the driver's steering torque is detected, thereby reducing the discomfort caused to the driver.

[0018] Technical Solution

[0019] The driving assistance system for a vehicle of the present invention comprises: a steering wheel contact position detection unit that detects a steering wheel contact position of a driver; a steering torque detection unit that detects a steering torque of the driver; and a driving mode setting operation unit that has at least a first driving assistance mode for performing automatic driving subject to the driver's grip of the steering wheel, a second driving assistance mode for performing automatic driving not subject to the driver's grip of the steering wheel, and a manual driving mode in which the driver steers the vehicle as driving modes of the vehicle, and sets the above modes according to driving conditions. The driving assistance system for the vehicle further comprises: a steering override determination unit that determines whether the detected steering torque is a steering override based on the driver's intention or a false detection based on the steering wheel contact position of the driver detected by the steering wheel contact position detection unit and the steering torque detected by the steering torque detection unit. The driving mode setting operation unit continues the current driving mode when the steering override determination unit determines that the detection is a false detection during driving in the first driving assistance mode or the second driving assistance mode, and shifts the driving mode to the manual driving mode when the steering override determination unit determines that the steering override is the steering override.

[0020] Effects of the Invention

[0021] According to the present invention, during driving in the first driving assistance mode conditioned on the control of the steering wheel, or the second driving assistance mode not conditioned on the control of the steering wheel, when it is determined that the driver has mistakenly touched the steering wheel, the current driving mode is continued. In addition, when it is determined that the steering is overcontrolled, the driving mode is transferred to the manual driving mode. Therefore, even if the steering torque of the driver is detected, the immediate transfer to the manual driving mode can be prevented, thereby reducing the discomfort caused to the driver. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a simplified diagram of the vehicle's driving assistance system.

[0023] Figure 2 This is a front view of a steering wheel equipped with a steering wheel touch sensor.

[0024] Figure 3 is a flowchart showing a driving mode setting procedure.

[0025] Figure 4 : is a flowchart showing a driving assistance mode processing subroutine.

[0026] Figure 5 : is a flowchart showing a first driving assistance mode execution condition determination processing subroutine.

[0027] Figure 6 : is a flowchart showing a second driving assistance mode execution condition determination processing subroutine.

[0028] Figure 7 1 is a flowchart showing a manual driving mode transition processing subroutine.

[0029] Figure 8 (a) is a schematic diagram of a table for setting the assist torque gain. Figure 8 (b) is a schematic diagram of a graph showing a transition ratio between the first driving assistance mode and the manual driving mode.

[0030] Fig. 9 (a) is an explanatory diagram showing a state in which the road curvature recognized by the camera unit coincides with the road curvature on the map, Fig. 9 (b) is an explanatory diagram showing a state in which the road curvature recognized by the camera unit is different from the road curvature on the map.

[0031] Explanation of symbols

[0032] 1…driving assistance system, 2…steering wheel, 2a…wheel rim, 2b…wheel spoke, 11…positioning unit, 12…map positioning operation unit, 12a…vehicle position estimation operation unit, 12b…map information acquisition unit, 13…GNSS receiver, 14…autonomous driving sensor, 18…high-precision road map database, 21…camera unit, 21a…main camera, 21b…auxiliary camera, 21c…image processing unit (IPU), 21d…front driving environment recognition unit, 22…driving mode setting operation unit, 41…automatic driving switch, 42…left and right steering wheel touch sensors, 42l…left steering wheel touch sensor, 42r…right steering wheel touch sensor Steering wheel touch sensor, 43…upper and lower steering wheel touch sensor, 43d…lower steering wheel touch sensor, 43u…upper steering wheel touch sensor, 44…steering torque sensor, 45…notification device, 51…automatic driving control unit, F1…first driving assistance mode execution flag, F2…second driving assistance mode execution flag, kG…assistance torque gain, kGO…manual takeover determination threshold, M…own vehicle, RCAM…camera curvature, RMPU…map curvature, t1, t2…set time, tim1, t2…attention time, Tst…steering torque, Tstd…steering assist torque, Tsto…steering override determination threshold DETAILED DESCRIPTION

[0033] Hereinafter, one embodiment of the present invention will be described based on the drawings. Figure 1 The driving assistance system shown is installed in the vehicle M (refer to Fig. 9 ). The driving assistance system 1 has a locator unit 11 and a camera unit 21 as a driving environment recognition unit as sensor units for detecting the shape of the surrounding road. The two units 11 and 21 constitute a completely independent multi-system that is independent of each other. In addition, in the event that one of the two units 11 and 21 fails, the other unit 11 and 21 is used to temporarily continue the automatic driving, thereby constructing a redundant system that allows the driver to safely take over the driving of the vehicle M.

[0034] The driving assistance system 1 uses the locator unit 11 and the camera unit 21 to monitor whether the road shape during the current driving process is the same, and continues the automatic driving if it is the same. In addition, as an example of the detected same road shape, the road curvature is shown in this embodiment.

[0035] The locator unit 11 estimates the position of the host vehicle M on the road map (host vehicle position) and acquires road map data ahead of the host vehicle position. On the other hand, the camera unit 21 identifies the left and right dividing lines that divide the driving lane of the host vehicle M, finds the road curvature at the center of the dividing line, and detects the lateral position deviation of the host vehicle M in the vehicle width direction based on the center of the lane dividing line.

[0036] The locator unit 11 has a map positioning operation unit 12 and a high-precision road map database 18 as a storage unit. The map positioning operation unit 12, the front driving environment recognition unit 21d described later, the driving mode setting operation unit 22 as a driving mode setting operation unit, and the automatic driving control unit 51 described later are composed of a well-known microcomputer having a CPU, RAM, ROM, etc. and its peripheral devices, and the ROM stores in advance a program executed by the CPU and / or fixed data such as a data table.

[0037] A GNSS (Global Positioning System) receiver 13 and an autonomous driving sensor 14 are connected to the input side of the map positioning operation unit 12. The GNSS receiver 13 receives positioning signals sent from a plurality of positioning satellites. In addition, the autonomous driving sensor 14 enables the vehicle to drive autonomously in an environment such as driving in a tunnel where the sensitivity of receiving signals from GNSS satellites is low and positioning signals cannot be effectively received. The autonomous driving sensor 14 is composed of a vehicle speed sensor, a gyro sensor, and a longitudinal acceleration sensor. That is, the map positioning operation unit 12 performs positioning based on the moving distance and direction based on the vehicle speed detected by the vehicle speed sensor, the angular velocity detected by the gyro sensor, and the longitudinal acceleration detected by the longitudinal acceleration sensor.

[0038] The map positioning calculation unit 12 includes a vehicle position estimation calculation unit 12 a as a function of estimating the vehicle position, and a map information acquisition unit 12 b that performs map matching on a road map to identify the estimated vehicle position and acquires road shape information ahead.

[0039] In addition, the high-precision road map database 18 is a large-capacity storage medium such as HDD, which stores high-precision road map information (dynamic map). The high-precision road map information includes lane data (lane width data, lane center position coordinate data, lane travel azimuth data, speed limit, etc.) required for automatic driving, and the lane data is stored at intervals of several meters for each lane on the road map.

[0040] The map information acquisition unit 12b acquires the road map information of the current location based on the road map information stored in the high-precision road map database 18. Furthermore, based on the destination set by the driver during automatic driving, for example, the route map information from the vehicle position (current location) estimated by the vehicle position estimation operation unit 12a to the destination is acquired based on the road map information, and the acquired route map information (lane data on the route map and its surrounding information) is sent to the vehicle position estimation operation unit 12a.

[0041] The vehicle position estimation operation unit 12a obtains the position coordinates of the vehicle M based on the positioning signal received by the GNSS receiver 13, performs map matching on the position coordinates on the route map information to estimate the vehicle position (current location) on the road map, and determines the driving lane, and obtains the road shape of the driving lane stored in the route map information, that is, in this embodiment, the road curvature (hereinafter referred to as "map curvature") RMPU [1 / m] of the center of the lane (refer to Fig. 9 ) and store them in sequence.

[0042] In addition, in an environment such as driving in a tunnel where the sensitivity of the GNSS receiver 13 is reduced and it is impossible to receive effective positioning signals from the positioning satellite, the vehicle position estimation operation unit 12a switches to autonomous navigation for estimating the vehicle position based on the vehicle speed detected by the vehicle speed sensor, the angular velocity detected by the gyroscope sensor, the longitudinal acceleration detected by the longitudinal acceleration sensor, etc., infers the vehicle position on the road map, and obtains the curvature (map curvature) RMPU of the road on which the vehicle M is traveling.

[0043] On the other hand, the camera unit 21 is fixed to the center of the upper part of the front part of the interior of the host vehicle M, and includes an on-board camera composed of a main camera 21a and a sub-camera 21b arranged at left-right symmetrical positions across the center in the vehicle width direction, an image processing unit (IPU) 21c, and a front driving environment recognition unit 21d. The camera unit 21 is a stereo camera that captures a predetermined area in front of the host vehicle M captured by the two cameras 21a and 21b. The IPU 21c performs predetermined image processing on the surrounding environment images in front of the driving direction captured by the two cameras 21a and 21b, and outputs them to the front driving environment recognition unit 21d.

[0044] The front driving environment recognition unit 21d calculates the road shape of the road on which the vehicle M is traveling (the road on which the vehicle M is traveling) based on the received driving environment image information in front of the vehicle M, that is, in the present embodiment, the road curvature [1 / m] of the dividing line that divides the left and right and the width (lane width) between the left and right dividing lines. There are many known methods for obtaining the road curvature and lane width, but for example, the road curvature is based on the driving environment image information, and the left and right dividing lines are identified by binarization processing based on brightness difference, and the curvature of the left and right dividing lines is calculated for each predetermined interval using a curve approximation formula based on the least squares method, and then the lane width is calculated based on the difference in curvature between the two dividing lines. Then, based on the curvature of the left and right dividing lines and the lane width, the road curvature (hereinafter referred to as "camera curvature") RCAM[1 / m] (refer to Fig. 9Then, the map curvature RMPU acquired by the vehicle position estimation calculation unit 12a and the camera curvature RCAM estimated by the front driving environment recognition unit 21d are read into the driving mode setting calculation unit 22.

[0045] In addition, the front driving environment recognition unit 21d detects the presence of a preceding vehicle traveling in front of the host vehicle M based on the acquired driving environment image information. And, when the preceding vehicle is detected, the preceding driving environment recognition unit 21d calculates the inter-vehicle distance (distance), relative vehicle speed, and inter-vehicle time with the host vehicle M. It should be noted that the detection of the preceding vehicle using a stereo camera, the acquisition of the inter-vehicle distance, the relative vehicle speed, and the inter-vehicle time are known techniques, and thus the description thereof is omitted here.

[0046] The input side of the driving mode setting calculation unit 22 is connected to the above-mentioned vehicle position estimation calculation unit 12a and the front driving environment recognition unit 21d, and is also connected to the automatic driving switch 41 for the driver to turn on / off the automatic driving, the steering wheel 2 (see FIG. 2 ) for detecting the driver's position. Figure 2 ), and a steering torque sensor 44 as a steering torque detection unit. It should be noted that the two steering wheel touch sensors 42 and 43 correspond to the steering wheel contact position detection unit for detecting the driver's steering wheel contact position of the present invention.

[0047] The front driving environment information acquired by the camera unit 21 is also read to the ACC control unit (not shown). When a preceding vehicle is detected in front of the lane in which the host vehicle M is traveling based on the preceding driving environment information, the ACC control unit performs the preceding vehicle following driving control while maintaining a predetermined inter-vehicle distance with respect to the preceding vehicle. In addition, when no preceding vehicle is detected, the host vehicle M travels at a set speed pre-set by the driver.

[0048] The above-mentioned steering wheel touch sensors 42, 43 are composed of pressure-sensitive sensors, pressure sensors, capacitive sensors, etc. Figure 2 As shown, the left-right steering wheel touch sensor 42 is composed of a left steering wheel touch sensor 421 and a right steering wheel touch sensor 42r. In addition, the up-down steering wheel touch sensor 43 is composed of an upper steering wheel touch sensor 43u and a lower steering wheel touch sensor 43d.

[0049] It should be noted that the left steering wheel touch sensor 421 and the right steering wheel touch sensor 42r correspond to the first steering wheel contact position detection unit of the present invention, and the upper steering wheel touch sensor 43u and the lower steering wheel touch sensor 43d correspond to the second steering wheel contact position detection unit of the present invention.

[0050] The center of the rim 2a of the steering wheel 2 is supported on a steering shaft (not shown) via the spoke 2b. The left steering wheel touch sensor 421 and the right steering wheel touch sensor 42r are arranged in a slightly larger range than the recommended steering wheel holding area for the driver to hold the rim 2a in a correct posture (for example, if it is represented by the hands of a clock, the left hand side is approximately between the short hand and the long hand at 8:50, and the right hand side is approximately between the short hand and the long hand at 2:20). In addition, the upper steering wheel touch sensor 43u and the lower steering wheel touch sensor 43d are arranged above and below the rim 2a, which is not recommended for holding the steering wheel, and is easily touched by the hands and / or knees of the driver when performing actions such as turning back (for example, if it is represented by the hands of a clock, the upper side is approximately between the short hand and the long hand at 11:05, and the lower side is approximately between the short hand and the long hand at 5:35).

[0051] The steering torque sensor 44 detects a steering torque Tst applied by the driver to the steering shaft based on the torsion of the steering shaft (not shown), and determines the presence or absence of steering intervention (steering override) based on the steering torque Tst.

[0052] In addition, a notification device 45 as a notification unit composed of an audio speaker and / or a display is connected to the output side of the driving mode setting operation unit 22. In addition, an automatic driving control unit 51 is connected to the driving mode setting operation unit 22 in a two-way communication manner. The automatic driving control unit 51 executes the corresponding driving mode according to the driving mode (manual driving mode, first driving assistance mode, second driving assistance mode, and automatic retreat mode) set by the driving mode setting operation unit 22.

[0053] The driving mode setting calculation unit 22 always compares the map curvature RMPU ahead of the vehicle position estimated by the vehicle position estimation calculation unit 12a and the camera curvature RCAM estimated by the front driving environment recognition unit 21d. That is, the consistency (reliability) [%] of the two curvatures RMPU and RCAM in the same distance interval ahead is investigated based on the vehicle position on the map and the vehicle position obtained by actual driving, respectively. If the consistency exceeds a preset threshold (for example, 95 to 99 [%]), it is determined to be consistent, and if it is below the threshold, it is determined to be inconsistent.

[0054] For example, Fig. 9 As shown in (a), when the map curvature RMPU acquired by the locator unit 11 and the camera curvature RCAM recognized by the front traveling environment recognition unit 21d match, it is evaluated that the host vehicle M is definitely traveling on the target traveling road.

[0055] On the other hand, Fig. 9As shown in (b), when the positioning position obtained by the GNSS receiver 13 is in error and the map is matched to an adjacent lane, the locator unit 11 mistakenly regards the map curvature RMPU of the adjacent lane as the road curvature on the vehicle's road, so the consistency (reliability) of the two curvatures RCAM and RMPU is evaluated to be low. Alternatively, when the camera curvature RCAM cannot be obtained by the front driving environment recognition unit 21d during driving in a state of poor visibility such as during rain, the consistency is also evaluated to be low (less than the threshold).

[0056] If it is determined that the two curvatures RMPU and RCAM are consistent, the second driving assistance mode is continued. Alternatively, the driving mode is shifted from the first driving assistance mode to the second driving assistance mode. It should be noted that when the driving mode is shifted, the notification device 45 notifies the driver of the situation in advance.

[0057] In this embodiment, a manual driving mode in which the driver performs steering by himself, a first driving assistance mode, a second driving assistance mode, and an automatic avoidance mode are set as driving modes, and the first driving assistance mode and the second driving assistance mode are included in the category of automatic driving. Here, the first driving assistance mode and the second driving assistance mode have in common that the vehicle M is automatically driven along the target road (automatic driving), but the first driving assistance mode is a driving mode conditioned on the driver holding the steering wheel, and the second driving assistance mode is a driving mode not conditioned on the driver holding the steering wheel (not holding the steering wheel).

[0058] For example, when the camera unit 21 fails temporarily, although it is difficult to continue the automatic driving in the second driving assistance mode, the automatic driving will not be suddenly transferred to the manual driving mode, but the driver will be notified of the transfer to the first driving assistance mode and asked to hold the steering wheel. Then, after the driver holds the steering wheel 2, the automatic driving will be continued based on the position of the vehicle estimated by the map positioning calculation unit 12.

[0059] This also applies when the vehicle position inferred by the map positioning calculation unit 12 fails. After the driver holds the steering wheel 2, the center of the left and right dividing lines recognized by the camera unit 21 is set as the target road, and the vehicle M is driven along the target road.

[0060] In addition, during driving in the automatic driving mode (the first driving assistance mode or the second driving assistance mode), when the driver's steering intervention (steering override) is detected, the driving mode is transferred from the automatic driving mode to the manual driving mode.

[0061] However, in Figure 2In the steering wheel 2 shown, normally, if the driver touches (holds) the rim 2a with both hands in a correct posture while visually checking the front, the left steering wheel touch sensor 421 and the right steering wheel touch sensor 42r are both turned on. Therefore, when the driver steers in this posture and a steering intervention is detected based on the steering torque Tst detected by the steering torque sensor 44, it can be determined that the steering is overridden by the driver's intention. However, when at least one of the left steering wheel touch sensor 421 and the right steering wheel touch sensor 42r is turned off, or at least one of the upper steering wheel touch sensor 43u and the lower steering wheel touch sensor 43d is turned on, and a steering intervention is detected based on the steering torque Tst at this time, it can be determined that the driver is not steering in the correct posture, but simply erroneously touching (erroneously detecting).

[0062] If the driving mode is immediately switched to the manual driving mode when such a false contact (false detection) is made, the driver will feel uncomfortable. Therefore, in the present embodiment, it is appropriately determined whether the steering intervention (steering override) is based on the driver's intention or a false operation based on both the contact position of the driver's steering wheel 2 and the steering torque.

[0063] The driving mode setting calculation unit 22 Figure 3 to Figure 7 In the shown routine for setting the driving mode, it is determined whether the steering override is based on the driver's intention or is simply an erroneous contact (false detection).

[0064] If the vehicle M is moving, Figure 3 The driving mode setting program shown is started. First, in step S1, a signal from the automatic driving switch 41 is read. The automatic driving switch 41 is a switch that is turned on when the driver selects automatic driving. In step S2, it is checked whether the automatic driving switch 41 is turned on. If it is turned on, it proceeds to step S3, executes the driving assistance mode processing and exits the program. On the other hand, when the automatic driving switch 41 is turned off, it branches to step S4, executes the manual driving mode (turns off the automatic driving switch 41) and exits the program. If the manual driving mode is selected as the driving mode, the target route set by the existing navigation function that guides the vehicle M to the destination is displayed on the display (not shown). The driver drives the vehicle M by himself according to the display and voice guidance.

[0065] In addition, the driving assistance mode processing in step S3 is performed according to Figure 4In this subroutine, first, in step S11, it is checked whether the first driving assistance mode can be executed. Whether the first driving assistance mode can be executed is checked based on the dividing line that divides the left and right lanes of the host vehicle M recognized by the front driving environment recognition unit 21d of the camera unit 21, the left and right steering wheel touch sensors 42 (left steering wheel touch sensor 42l, right steering wheel touch sensor 42r) and the steering torque Tst detected by the steering torque sensor 44.

[0066] As described above, when the camera unit 21 recognizes the dividing line dividing the lane in which the host vehicle M is traveling to the left and right and sets the target travel path, the control is executed. Figure 5 The first driving assistance mode execution condition determination processing subroutine is shown. In addition, when the target travel road is not set, the mode is transferred to the manual driving mode.

[0067] exist Figure 5 In the subroutine shown, first, in step S31, signals from the left and right steering wheel touch sensors 42 (left steering wheel touch sensor 421, right steering wheel touch sensor 42r) are read to check whether the driver is holding the steering wheel in a correct posture.

[0068] And, when both the left steering wheel touch sensor 421 and the right steering wheel touch sensor 42r are turned on, it is determined that the driver is holding the steering wheel in a correct posture, and the process proceeds to step S32. In addition, when at least one of the left steering wheel touch sensor 421 and the right steering wheel touch sensor 42r is turned off, it is determined that the driving posture is incorrect, and the process branches to step S33.

[0069] If the process proceeds to step S32, the steering torque Tst detected by the steering torque sensor 44 is read and compared with the steering override determination threshold value Tsto in step S34. The steering override determination threshold value Tsto is a value used to investigate whether the driver's steering is based on his own intention or is simply an erroneous contact, and can be a fixed value or a variable value set based on the vehicle speed.

[0070] Furthermore, when Tst≤Tsto, even if the driver's hand and / or knee touches the steering wheel 2, it is determined to be a simple mistaken contact, and the process goes to step S35, where the first driving assistance mode execution flag F1 is set (F1←1), and the process goes to step S40. Figure 4 In the case of Tst>Tsto, it is determined that the steering override is based on the driver's own intention, and the process returns to step S12. Figure 3 Step S4, continue the manual driving mode and exit the program.

[0071] Therefore, the processing in the above-mentioned steps S31, S32, and S34 corresponds to the steering override determination unit of the present invention.

[0072] In this way, since the execution conditions of the first driving assistance mode are that both the left and right steering wheel touch sensors 42 are turned on and the steering torque Tst is less than the steering override determination threshold value Tsto, it is possible to effectively prevent misjudgment. In addition, when the driver touches (holds) the upper and lower parts of the rim 2a of the steering wheel 2 (at least one of the upper and lower steering wheel touch sensors 43 is turned on), the driver is required to hold the steering wheel in the correct position, thereby prompting the driver to pay attention.

[0073] In addition, if the branch from step S31 is to step S33, the signal from the upper and lower steering wheel touch sensors (upper steering wheel touch sensor 43u, lower steering wheel touch sensor 43d) 43 is read to check whether the contact position of the steering wheel 2 is abnormal. And, if both the upper steering wheel touch sensor 43u and the lower steering wheel touch sensor 43d are turned off, since the driver does not hold the steering wheel, the condition is not met, so the process proceeds to step S36, the first driving assistance mode execution flag F1 is cleared (F1←0), and the process proceeds to step S36. Figure 4 Step S12.

[0074] In addition, when at least one of the upper steering wheel touch sensor 43u and the lower steering wheel touch sensor 43d is turned on, it is determined that the driver is not holding the steering wheel in the correct posture, and the process proceeds to step S37. The notification device 45 notifies the driver of the requirement to hold the steering wheel in the correct position, such as "Please hold the steering wheel in the correct position", and the process proceeds to step S38. In step S38, the reminder time tim1 is incremented (tim1←tim1+1), and the process proceeds to step S39, which is compared with the set time t1 (for example, 3 to 5 [sec]). If tim1<t1, the process returns to step S31 and waits until the driver holds the correct steering wheel holding position (both the left steering wheel touch sensor 42l and the right steering wheel touch sensor 42r are turned on).

[0075] On the other hand, even after the reminder time tim1 (tim1 ≥ t1), if at least one of the left steering wheel touch sensor 421 and the right steering wheel touch sensor 42r is still turned on, the process proceeds to step S40, the automatic avoidance mode is executed, and the program ends. If the automatic avoidance mode is executed, the automatic driving control unit 51 causes the vehicle M to travel along the current driving lane with the speed limited to the legal or specified minimum speed, guides the vehicle to a safe place such as a roadside area, and stops it.

[0076] Then, if you enter Figure 4In step S12, the value of the first driving assistance mode execution flag F1 is referred to. If F1 = 1, it is determined that the condition is met and the process proceeds to step S13. Otherwise, if F1 = 0, it is determined that the condition is not met and the process returns to step S14. Figure 3 Step S4, continue the manual driving mode and exit the program.

[0077] Then, if the process proceeds to step S13, a command signal for executing the first driving assistance mode is sent to the automatic driving control unit 51, and the process proceeds to step S14. In step S14, it is checked whether the first driving assistance mode can be shifted to the second driving assistance mode.

[0078] Whether the second driving assistance mode can be shifted is determined based on the consistency between the map curvature RMPU and the camera curvature RCAM, the left and right steering wheel touch sensor 42, and the up and down steering wheel touch sensor 43. And, as described above, when the map curvature RMPU and the camera curvature RCAM are consistent (for example, the consistency is 95 to 99 [%] or more), the second driving assistance mode is executed. Figure 6 The second driving assistance mode execution condition determination processing subroutine is shown. It should be noted that when the map curvature RMPU and the camera curvature RCAM do not coincide with each other, the first driving assistance mode is executed.

[0079] exist Figure 6 In the subroutine shown, first, in step S41, the signals from the left and right steering wheel touch sensors 42 (the left steering wheel touch sensor 421 and the right steering wheel touch sensor 42r) are read, and when both the left steering wheel touch sensor 421 and the right steering wheel touch sensor 42r are turned off, the process proceeds to step S42. In addition, when at least one of the left steering wheel touch sensor 421 and the right steering wheel touch sensor 42r is turned on, the process branches to step S43.

[0080] If the process proceeds to step S42, the signal from the upper and lower steering wheel touch sensors (upper steering wheel touch sensor 43u, lower steering wheel touch sensor 43d) 43 is read. If at least one of the upper steering wheel touch sensor 43u and the lower steering wheel touch sensor 43d is turned on, it is determined to be a simple false touch, and the process branches to step S44, and the notification device 45 notifies the driver of a request to not hold the steering wheel, such as "you are touching the steering wheel", and the process proceeds to step S45.

[0081] In addition, when both the upper steering wheel touch sensor 43u and the lower steering wheel touch sensor 43d are turned off, it is determined that the driver has completely removed his hands from the steering wheel 2, and the process proceeds to step S45.

[0082] Furthermore, if the process proceeds from step S42 or step S44 to step S45, it is determined that the second driving assistance mode can be executed, the second driving assistance mode execution flag F2 is set (F2←1), and the process proceeds to step S46. Figure 4 Step S15.

[0083] Thus, in this embodiment, when at least one of the upper steering wheel touch sensor 43u and the lower steering wheel touch sensor 43d is turned on, it is determined as a simple erroneous touch by the driver, and the second driving assistance mode execution flag F2 is set only to request the driver to stop holding the steering wheel, so that the second driving assistance mode can be continued. As a result, the driver does not need to pay attention to how much contact is made on the steering wheel 2, and high convenience can be obtained.

[0084] In addition, if the branch from step S41 to step S43 is made, the notification device 45 notifies the driver of the request to not hold the steering wheel, such as "since you are touching the steering wheel, the automatic driving with your hands off the steering wheel is canceled", and the process proceeds to step S46. In step S46, the reminder time tim2 is incremented (tim2←tim2+1), and the process proceeds to step S47, where it is compared with the set time t2 (for example, 3 to 5 [sec]). If tim2<t2, the process returns to step S41, and waits until the driver takes his hands off the normal holding position (both the left steering wheel touch sensor 421 and the right steering wheel touch sensor 42r are turned off).

[0085] In addition, when tim2 ≥ t2, it is determined that the driver has no intention to take his hands off the steering wheel 2, and the process proceeds to step S48, the second driving assistance mode execution flag F2 is cleared (F2←0), and the process proceeds to step S49. Figure 4 Step S15.

[0086] In step S15, the value of the second driving assistance mode execution flag F2 is referred to, and when it is determined that the condition of F2 = 1 is satisfied, the process proceeds to step S16. On the other hand, when it is determined that the condition of F2 = 0 is not satisfied, the process branches to step S17.

[0087] If the process proceeds to step S16, a command signal for executing the second driving assistance mode is sent to the automatic driving control unit 51, and the process proceeds to step S18. In step S18, the above-mentioned process is executed again to check whether the driving mode is to be transferred from the second driving assistance mode to the first driving assistance mode. Figure 5 The first driving assistance mode execution condition determination processing subroutine is shown.

[0088] In the first driving assistance mode execution condition determination processing subroutine, the left and right steering wheel touch sensors 42 are both turned on and the steering torque Tst is less than the steering override determination threshold Tsto as the transition condition to the first driving assistance mode. Therefore, if the driver mistakenly touches the left and right steering wheel touch sensors 42, the transition condition is not met and the second driving assistance mode can be continued, so it is possible to prevent misjudgment and obtain high convenience.

[0089] Next, the process proceeds to step S19 to check the value of the first driving assistance mode execution flag F1. If F1 = 0, the process proceeds to step S20 to read the signal from the automatic driving switch 41. If it is on, the process returns to step S14, and in steps S14 and S15, the second driving assistance mode execution condition is checked. If it is satisfied, the second driving assistance mode is continued. If the automatic driving switch 41 is off, the process returns to step S21. Figure 3 In step S4, the manual driving mode is executed (the automatic driving switch 41 is turned off), and the program is exited. In addition, in step S19, if it is determined that F1=1, the program branches to step S21, the driving mode is transferred to the first driving assistance mode, and the program is exited.

[0090] On the other hand, when the process branches from step S15 to step S17, the steering torque Tst detected by the steering torque sensor 44 is read, and the steering torque Tst is compared with the steering override determination threshold value Tsto in step S22. The steering override determination threshold value Tsto is a value used to check whether the steering is based on the driver's intention or a simple erroneous contact (erroneous detection), and can be a fixed value or a variable value set based on the vehicle speed.

[0091] Furthermore, when Tst≤Tsto, even if the driver's hand and / or knee touches the steering wheel 2, it is determined to be a simple mistaken contact and the program is exited. Figure 6 Step S41 and Figure 4 Steps S17 and S22 correspond to the steering override determination unit of the present invention.

[0092] Then, when the subsequent operation is performed, Figure 4 In steps S11 and S12, the first driving assistance mode execution condition is checked, and the driving mode is shifted to the first driving assistance mode if it is satisfied. In addition, if Tst>Tsto, it is determined that the steering is overridden, and the process proceeds to step S23. After executing the manual driving mode shift process, the process returns to step S24. Figure 3 In step S4, the manual driving mode is executed (the automatic driving switch 41 is turned off), and the program is exited.

[0093] The above manual driving mode transfer process is based on Figure 7 The manual driving mode transfer processing subroutine shown in the figure is executed. The manual driving mode transfer processing is a processing for gradually reducing the ratio of the steering assist torque during automatic steering generated by the EPS motor (not shown) provided in the EPS system of the vehicle M when the driving mode is transferred from the first driving assistance mode to the manual driving mode, and gradually transferring to the manual driving mode based on the driver's steering wheel operation.

[0094] That is, first, in step S51, the steering assist torque Tstd output from the EPS motor to the steering system is read, and in step S52, the assist torque gain kG is set based on the steering torque Tst generated by the driver's steering wheel operation detected by the steering torque sensor 44 and with reference to the assist torque gain table. Figure 8 The concept of the assist torque gain map is shown in (a).

[0095] As shown in the figure, the assist torque gain kG is set to 100[%] when the steering torque Tst is 0, that is, in the open state where the driver does not intervene in the steering, and is set to a lower value as the steering torque Tst increases. When the steering torque Tst reaches 0[%], the driver's manual steering is completely taken over. Figure 8 In the diagram, positive (+) indicates a clockwise direction, and negative (-) indicates a counterclockwise direction.

[0096] Next, the process proceeds to step S53, where the assist torque gain kG is multiplied by the steering assist torque Tstd to set a new steering assist torque Tstd (Tstd←kG·Tstd), and the process proceeds to step S54, where the new steering assist torque Tstd is output to the EPS control system and the EPS motor (not shown) is activated. The steering intervention by the driver starts with steering torque Tst=0 and gradually increases.

[0097] Therefore, by using the gain corresponding to the steering torque Tst to reduce the steering assist torque Tstd from the EPS motor, Figure 8 As shown in (b), when the driver intervenes in the steering, the driving mode will not be suddenly switched to the manual driving mode, but can be smoothly transferred from the first driving assistance mode to the manual driving mode.

[0098] In addition, at this time, the assist torque gain kG can also be corrected using the reliability [%] set based on the steering reliability. The steering reliability is set according to the degree of emergency. For example, if there is a possibility of colliding with an obstacle or deviating from the dividing line in the direction of the steering torque Tst, the steering reliability is reduced to avoid it through automatic steering.

[0099] Therefore, the steering reliability is to compare the steering direction and steering amount with the target travel path set by the automatic driving control unit 51, and the greater the deviation, the lower the value is set. And then, it can be transferred to the automatic retreat mode. Thus, for example, when driving in the first driving assistance mode, when the driver is unconscious and unable to drive, it can be quickly responded.

[0100] Then, the process proceeds to step S55, where the assist torque gain kG is compared with the manual takeover determination threshold kGO, and the process is repeated until kG ≤ kGO. When kG ≤ kGO is reached, the process returns to step S56. Figure 3 In step S4, the manual driving mode is executed (the automatic driving switch 41 is turned off), and the program is exited.

[0101] Thus, according to the present embodiment, during driving in the second driving assistance mode, even if the driver accidentally touches the left or right steering wheel touch sensor 42, when the steering torque Tst is less than the steering override determination threshold value Tsto, the transition condition to the first driving assistance mode is not satisfied. Therefore, in the case of simple accidental contact, the transition to the manual driving mode can be avoided, reducing the discomfort caused to the driver.

[0102] Furthermore, when both left and right steering wheel touch sensors 42 are turned on and the steering torque Tst exceeds the steering override determination threshold value Tsto, it is determined that the steering intervention (steering override) is based on the driver's intention. Therefore, the steering override can be appropriately determined and erroneous determination can be avoided.

[0103] In addition, the present invention is not limited to the above-mentioned embodiment, and for example, the left and right steering wheel touch sensor 42 and the up and down steering wheel touch sensor 43 can be any sensor as long as they detect the position of the driver holding the steering wheel. Therefore, the steering wheel touch sensor can be arranged on the entire circumference of the rim 2a of the steering wheel 2, and the contact position can be detected by dividing the steering wheel touch sensor into parts with predetermined angles.

Claims

1. A driving assistance system for a vehicle, characterized in that: have: a steering wheel contact position detection unit, which detects the driver's steering wheel contact position using a first steering wheel contact position detection unit and a second steering wheel contact position detection unit, wherein in a front view of the steering wheel of the vehicle, the first steering wheel contact position detection unit is composed of a left steering wheel touch sensor in a left area of ​​the rim of the steering wheel and a right steering wheel touch sensor in a right area of ​​the rim, and are arranged in left and right areas of the rim, and the second steering wheel contact position detection unit is composed of an upper steering wheel touch sensor in an upper area of ​​the rim and a lower touch sensor in a lower area of ​​the rim, and are arranged in upper and lower areas of the rim sandwiched by left and right areas; a steering torque detection unit, which detects the steering torque of the driver; as well as a driving mode setting calculation unit having at least a first driving assistance mode for performing automatic driving subject to the driver's control of the steering wheel, a second driving assistance mode for performing automatic driving not subject to the driver's control of the steering wheel, and a manual driving mode in which the driver himself performs steering as driving modes of the host vehicle, and setting each mode according to driving conditions, The driving assistance system of the vehicle also has: a steering override determination unit that determines whether the detected steering torque is a steering override based on the driver's intention or an erroneous detection based on the driver's steering wheel contact position detected by the steering wheel contact position detection unit and the steering torque detected by the steering torque detection unit, The driving mode setting calculation unit continues the current driving mode when the steering override determination unit determines that the vehicle is traveling in the first driving assistance mode or the second driving assistance mode, and shifts the driving mode to the manual driving mode when the steering override determination unit determines that the vehicle is traveling in the first driving assistance mode or the second driving assistance mode. When the steering wheel contact position detection unit detects contact with the second steering wheel contact position detection unit during driving in the first driving assistance mode, the driving mode setting operation unit calls attention to the contact with the first steering wheel contact position detection unit and continues the first driving assistance mode for a first set time. When the steering wheel contact position detection unit detects contact with the first steering wheel contact position detection unit within the first set time, the driving mode setting calculation unit continues the first driving assistance mode, When the steering wheel contact position detection unit detects contact at the second steering wheel contact position detection unit even after the first set time has passed, the driving mode setting calculation unit switches the driving mode to an automatic retreat mode for limiting the speed of the host vehicle and guiding the vehicle to a safe place. When the steering wheel contact position detection unit detects contact with the first steering wheel contact position detection unit during driving in the first driving assistance mode, the driving mode setting operation unit makes a request to not hold the steering wheel and makes the first driving assistance mode continue for a second set time. If contact with the first steering wheel contact position detection unit is still detected after the second set time, it is determined that the execution condition of the second driving assistance mode is not met.

2. The driving assistance system for a vehicle according to claim 1, characterized in that: When the steering wheel contact position detection unit detects the contact position at the second steering wheel contact position detection unit during driving in the second driving assistance mode, the driving mode setting calculation unit determines that it is an erroneous detection and continues the second driving assistance mode.

3. The driving assistance system for a vehicle according to claim 2, characterized in that: When the steering wheel contact position detection unit detects a contact position at the second steering wheel contact position detection unit during driving in the second driving assist mode, the driving mode setting calculation unit notifies the user to remove his hands from the steering wheel.

4. The driving assistance system for a vehicle according to claim 1, characterized in that: When the steering override determination unit determines that the steering override occurs during driving in the first driving assist mode, the driving mode setting calculation unit gradually reduces the ratio of the steering assist torque of the automatic steering to gradually shift to the manual driving mode.

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