Vehicle driving assistance device

Abstract

An automatic speed control unit (36) controls the speed of a vehicle within a range not exceeding a predetermined set speed limit. A sign recognition unit (38) recognizes a road sign speed limit of a road on which the vehicle travels on the basis of a road sign. An automatic speed-limit setting unit (40) can switch modes between an automatic setting mode for automatically setting the road sign speed limit as the set speed limit in the automatic speed control unit (36), and a manual setting mode for setting the road sign speed limit as the set speed limit in the automatic speed control unit (36) when the driver has performed a confirming operation. This vehicle driving assistance device is provided with a mode selection unit (42) that selects one of the automatic setting mode and the manual setting mode for each speed segment obtained by dividing the set speed limit into prescribed speed ranges, and sets the selected mode in the automatic speed-limit setting unit (40).

Description

Vehicle driving assistance device

[0001] The present invention relates to a vehicle driving assistance device.

[0002] Conventionally, a vehicle cruise control called ACC (adaptive cruise control or auto cruise control) has been known. ACC controls the speed of a vehicle so as to maintain a constant distance from a preceding vehicle within a range that does not exceed a predetermined ACC speed limit. The ACC speed limit is set, for example, manually by the driver. Patent Document 1 also proposes a vehicle cruise control device equipped with a traffic sign recognition system (TSR). The traffic sign recognition system recognizes road sign speed limits, which are the speed limits of the road on which the vehicle is traveling, based on road signs recognized by a camera mounted on the vehicle. The cruise control device automatically sets the road sign speed limit recognized using the traffic sign recognition system as the ACC speed limit, thereby eliminating manual operation by the driver.

[0003] Japanese Patent Application Publication No. 07-85400

[0004] However, when a road sign speed limit recognized using a traffic sign recognition system is automatically set as the ACC speed limit, the following problem may occur. For example, a first road sign for the lane in which the host vehicle is traveling may display a road sign speed limit of, for example, 100 km / h, while a second road sign for a lane branching off from the lane in which the host vehicle is traveling and heading toward a parking area or service area may display a road sign speed limit of, for example, 40 km / h. In this case, the camera of the host vehicle may capture an image of the second road sign, and the second road sign may be erroneously recognized as 40 km / h, which is different from the first road sign, as the road sign speed limit. In this case, if the vehicle's cruise control device automatically sets the ACC speed limit from 100 km / h to 40 km / h, the host vehicle's speed will be reduced, and the ACC will not function. While manually setting the ACC speed limit would solve the above problem, it would be cumbersome and less convenient if the road sign speed limit frequently changes between different values, such as 80, 100, and 120 km / h, on the road on which the vehicle is traveling. This problem also occurs in so-called automatic speed control (ASC, ASCD) systems that control the vehicle's speed to match the road sign speed limit recognized using a traffic sign recognition system, regardless of the vehicle ahead. The present invention has been made in light of these circumstances, and its purpose is to provide a vehicle driving assistance device that is advantageous in reducing driver operations and improving convenience when controlling the vehicle's speed based on the road sign speed limit recognized using a traffic sign recognition system.

[0005] To achieve the above object, one embodiment of the present invention provides a vehicle driving assistance device including an autospeed control unit that controls the speed of the vehicle within a range not exceeding a predetermined set speed limit, a sign recognition unit that recognizes road sign speed limits for the road on which the vehicle is traveling based on road signs, and an autospeed speed limit setting unit that is switchable between an automatic setting mode that automatically sets the road sign speed limit as the set speed limit of the autospeed control unit and a manual setting mode that sets the road sign speed limit as the set speed limit of the autospeed control unit when the driver performs an operation that accepts the setting.The device further includes a mode selection unit that selects one of the automatic setting mode and the manual setting mode for each of the section speeds that divide the set speed limit into predetermined speed ranges and sets the selected mode in the autospeed speed limit setting unit.Furthermore, one embodiment of the present invention is characterized in that the section speeds include a predetermined speed and a speed range other than the predetermined speed.Furthermore, one embodiment of the present invention is characterized in that the section speeds are set speed limits set in increments of 10 km / h. In one embodiment of the present invention, the mode selection unit performs an automatic mode selection operation in which, when the section speed is equal to or less than a predetermined threshold, the mode selection unit sets one of the automatic setting mode and the manual setting mode in the autospeed speed limit setting unit, and, when the section speed exceeds the threshold, the mode selection unit sets the other of the automatic setting mode and the manual setting mode in the autospeed speed limit setting unit. In another embodiment of the present invention, the threshold is set in the mode selection unit by operation of the driver. In another embodiment of the present invention, the vehicle is further provided with a notification unit that prompts the driver to accept the operation when the autospeed speed limit setting unit automatically selects the manual setting mode.

[0006] According to one embodiment of the present invention, a mode selection unit-set speed limit selects either an automatic setting mode or a manual setting mode for each of the zone speeds that divide the set speed limit into predetermined speed ranges. Therefore, by setting the set speed limit to the manual setting mode, it is possible to avoid a situation in which the set speed limit is erroneously changed and the ACC or auto speed control does not function. This advantageously eliminates the need for the driver to perform the troublesome operation of correcting an erroneously set set speed limit. Furthermore, by setting the set speed limit to the automatic setting mode, if the road sign speed limit for the road on which the vehicle is traveling changes frequently, the auto speed control unit automatically sets an appropriate set speed limit (road sign speed limit) without driver intervention. Therefore, setting the manual setting mode and the automatic setting mode for each zone speed is advantageous in reducing driver intervention during ACC or auto speed control, thereby improving convenience. Furthermore, if the demarcation speed is configured as a predetermined speed and a speed range other than the predetermined speed, a manual setting mode or an automatic setting mode can be set corresponding to each demarcation speed, which is advantageous in reducing driver operation during ACC or automatic speed control and improving convenience. Furthermore, if the demarcation speed is set in units of 10 km / h, this is the same unit as the road sign speed limit specified on general road signs posted on public roads, etc., which is advantageous in smoothly setting the automatic setting mode or the manual setting mode for each demarcation speed. Furthermore, according to one embodiment of the present invention, the mode selection unit performs an automatic mode selection operation in which, when the demarcation speed is equal to or less than a predetermined threshold, the mode selection unit sets one of the automatic setting mode and the manual setting mode in the autospeed speed limit setting unit, and, when the demarcation speed exceeds the threshold, the mode selection unit sets the other of the automatic setting mode and the manual setting mode in the autospeed speed limit setting unit. Therefore, since the automatic setting mode and manual setting mode for the section speed are set based on a single section speed threshold, there is no need to perform the operation of setting the automatic setting mode and manual setting mode for each section speed, which is advantageous in significantly reducing the burden on the driver and is even more advantageous in improving convenience.In addition, if the threshold value for the zone speed is set in the mode selection unit by the driver's operation, it is advantageous for the threshold value for the zone speed to be set flexibly according to the driver's intention. Furthermore, if a notification unit is provided that prompts the driver to accept when the autospeed speed limit setting unit automatically selects the manual setting mode, the driver can set the set speed limit after reliably recognizing that the mode is manual, which is advantageous for improving convenience.

[0007] FIG. 1 is a block diagram showing the configuration of a vehicle driving assistance device according to a first embodiment. (A) and (B) are explanatory diagrams of a display unit when selecting between an automatic setting mode and a manual setting mode. (A) and (B) are explanatory diagrams showing a display on the display unit corresponding to the manual setting mode. (B) are explanatory diagrams showing a display on the display unit corresponding to the automatic setting mode. (B) is an operation flowchart of the vehicle driving assistance device according to the first embodiment. (A) and (B) are explanatory diagrams of a display unit in which a plurality of threshold value selection switches are displayed in a second embodiment. (B) is an operation flowchart of the vehicle driving assistance device according to the second embodiment.

[0008] First Embodiment Next, a first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a vehicle driving assistance device 10 includes a vehicle speed sensor 12, a forward radar 14, a forward camera 16, an engine ECU 18, a transmission ECU 20, a brake ECU 22, a display unit 24, an operation unit 26, a speaker 28, and a driving assistance ECU 30. In this embodiment, a case will be described in which the vehicle driving assistance device 10 performs ACC, which controls the speed of the host vehicle so as to maintain a constant distance from a preceding vehicle. Of course, the present invention can also be applied to so-called automatic speed control (ASC, ASCD), which controls the speed of the host vehicle so as to conform to a road sign speed limit recognized using a traffic sign recognition system, regardless of the preceding vehicle.

[0009] The vehicle speed sensor 12 detects the vehicle speed of the host vehicle and supplies the detected vehicle speed to the driving assistance ECU 30. The forward radar 14 constitutes a distance measurement sensor. It is mounted at the front of the host vehicle, transmits a transmission wave toward the front of the vehicle, receives a reflected wave from a preceding vehicle, which is an object in front of the host vehicle, and detects the inter-vehicle distance between the host vehicle and the preceding vehicle, which is then supplied to the driving assistance ECU 30. Any of various conventionally known distance measurement sensors, such as a stereo camera, may be used as the distance measurement sensor. The forward camera 16 is installed, for example, above the front windshield of the host vehicle, and captures images of road signs, which are objects in front of the vehicle, to generate image information and supply it to the driving assistance ECU 30. Road signs include speed signs indicating the maximum speed limit (in other words, the maximum speed set by law or government ordinance) that indicates the maximum permitted speed on that road, as well as other signs such as no entry signs and stop signs.

[0010] The engine ECU 18 controls the operation of the engine based on control commands supplied from the driving assistance ECU 30. The transmission ECU 20 controls the operation of the transmission based on control commands supplied from the driving assistance ECU 30. The brake ECU 22 controls the operation of the brakes based on control commands supplied from the driving assistance ECU 30. In this way, the driving assistance ECU 30 controls the engine ECU 18, transmission ECU 20, and brake ECU 22, thereby controlling the speed of the host vehicle.

[0011] The display unit 24 displays information supplied from the driving assistance ECU 30 and various ECUs (not shown) for the driver to view. The display unit 24 is, for example, configured with a meter display 32 (see FIGS. 3 and 4 ) provided on the instrument panel. The meter display 32 displays information including vehicle speed (traveling speed), mileage, shift position, and various warnings (all not shown) in various conventionally known formats such as images, numbers, letters, icons, and indicators. Furthermore, as described below, the display unit 24 displays various information related to the ACC speed limit setting based on display information supplied from the driving assistance ECU 30. In addition to the meter display 32, the display unit 24 may also include a head-up display (HUD) that projects and displays the same information as above onto the front windshield glass in front of the driver. The configuration of the display unit 24 is arbitrary.

[0012] The operation unit 26 receives operations by the driver and supplies operation information to the driving assistance ECU 30. In this embodiment, a case will be described in which the operation unit 26 is configured by a touch panel 34 provided on the surface of the meter display 32. The operation unit 26 may be configured by various operation switches (not shown) provided on an instrument panel or the like, or may be configured by both the operation switches and the touch panel 34, and the configuration of the operation unit 26 is arbitrary.

[0013] The speaker 28 reproduces voice announcements (voice information) related to driving assistance and other voice announcements (voice information) to be notified within the vehicle cabin based on voice information supplied from the driving assistance ECU 30 and various ECUs not shown.

[0014] The driving assistance ECU 30 is configured to include a ROM that stores and remembers control programs and the like, a RAM that serves as an operating area for the control programs, a storage unit such as an EEPROM that stores various data in a rewritable manner, and an interface unit that interfaces with peripheral circuits, etc. By executing the control programs, the driving assistance ECU 30 functions as an autospeed control unit 36, a sign recognition unit 38, an autospeed speed limit setting unit 40, a mode selection unit 42, a notification unit 44, and a display control unit 46.

[0015] The autospeed control unit 36 ​​controls the speed of the host vehicle by controlling the engine ECU 18, the transmission ECU 20, and the brake ECU 22 within a range not exceeding a predetermined set speed limit based on the host vehicle speed supplied from the vehicle speed sensor 12. In this embodiment, the autospeed control unit 36 ​​controls the engine ECU 18, the transmission ECU 20, and the brake ECU 22 so as to maintain a constant inter-vehicle distance from the preceding vehicle within a range not exceeding a predetermined set speed limit based on the host vehicle speed supplied from the vehicle speed sensor 12 and the inter-vehicle distance from the preceding vehicle supplied from the forward radar 14, thereby controlling the speed of the host vehicle and causing the host vehicle to travel while tracking the preceding vehicle, thereby performing ACC for the host vehicle.

[0016] The sign recognition unit 38 recognizes road signs on the road on which the host vehicle is traveling based on image information of the road signs provided by the forward camera 16. As described above, road signs include speed signs, no entry signs, and stop signs. The sign recognition unit 38 not only has the function of recognizing road sign speed limits on the road on which the host vehicle is traveling based on image information of speed signs, but also has the function of recognizing no entry or stop restrictions ahead on the road on which the host vehicle is traveling based on no entry signs and stop signs. In this embodiment, a case will be described in which the sign recognition unit 38 has at least a first function of recognizing road signs based on image information from the forward camera 16. In addition to the above function, the sign recognition unit 38 may also have a second function of recognizing road signs based on road sign information included in map data (road information) acquired by the navigation device. In this case, if the first function fails to recognize a road sign, the second function is used to recognize the road sign.

[0017] The autospeed speed limit setting unit 40 sets the set speed limit in the autospeed control unit 36. In this embodiment, the autospeed speed limit setting unit 40 is configured to be switchable between two modes, an automatic setting mode and a manual setting mode, for setting the set speed limit in the autospeed control unit 36. The automatic setting mode is a mode in which a road sign speed limit recognized by the sign recognition unit 38 is automatically set as the set speed limit in the autospeed control unit 36. Therefore, in the automatic setting mode, the recognized road sign speed limit is automatically set as the set speed limit in the autospeed control unit 36 ​​without any operation by the driver. The manual setting mode is a mode in which the road sign speed limit recognized by the sign recognition unit 38 is set as the set speed limit in the autospeed control unit 36 ​​based on the driver's operation on the operation unit 26, in other words, when the driver performs an operation that agrees with the setting. Therefore, in the manual setting mode, the road sign speed limit recognized by the sign recognition unit 38 is not set in the autospeed control unit 36, and the set speed limit is not changed, unless the driver performs an operation that agrees with the setting.

[0018] The mode selection unit 42 selects either the automatic setting mode or the manual setting mode for each of the section speeds obtained by dividing the set speed limit into predetermined speed ranges, and sets the selected mode in the autospeed speed limit setting unit 40. FIG. 2 shows an example of a display displayed on the display unit 24 (meter display 32) when the mode selection unit 42 selects between the automatic setting mode and the manual setting mode. The left column displays speed limits typically displayed on road signs, such as 30 km / h, 40 km / h, 60 km / h, 80 km / h, 100 km / h, and 120 km / h, as section speeds. Because typical road sign speed limits are set in 10 km / h increments, the section speeds are also set in 10 km / h increments, making it easier for the driver to grasp the section speeds. Of course, the section speeds may be in units other than 10 km / h. In the right column, touch switches for selecting either the automatic setting mode or the manual setting mode are displayed for each section speed, and more specifically, touch switch 48A for selecting the automatic mode and touch switch 48B for selecting the manual setting mode are displayed. Therefore, the driver can assign either the automatic setting mode or the manual setting mode to each section speed by operating either touch switch 48A, 48B for the automatic setting mode or the manual setting mode for each section speed, and this operation causes the mode selection operation to be performed by mode selection unit 42. Therefore, in this case, the mode selection operation by mode selection unit 42 is performed based on the driver's operation on operation unit 26.

[0019] In addition, there are exceptional road sign speed limits such as 8 km / h, 10 km / h, 25 km / h, and 35 km / h that are not commonly seen on public roads and are specified on road signs in private roads, parking lots, port facilities, etc., and these speeds are also treated as section speeds. Here, section speeds are explained as follows: Section speeds are comprised of the following "speeds" and "speed ranges." 1) "Predetermined speeds." As described above, such "predetermined speeds" are assigned speeds that are determined by a single number, such as 30 km / h, 40 km / h, 60 km / h, 80 km / h, 100 km / h, and 120 km / h, which correspond to common road sign speed limits. 2) "Speed ​​ranges other than the predetermined speeds." Such "speed ranges other than the predetermined speeds" are assigned numerical ranges defined by upper and lower limits, such as 0 km / h to 29 km / h, 31 km / h to 39 km / h, 41 km / h to 59 km / h, 61 km / h to 79 km / h, 81 km / h to 99 km / h, and 101 km / h to 119 km / h. Therefore, exceptional road sign speed limits not found on typical public roads are included in the "speed ranges other than the predetermined speeds" defined in 2) above. Even when the sign recognition unit 38 recognizes a "speed range other than the predetermined speeds" as a demarcation speed, the autospeed speed limit setting unit 40 operates in the automatic setting mode or manual setting mode selected by the mode selection unit 42. 2A, the lower part of the right column and the lower part of the left column display touch switches 50A, 50B for selecting a demarcation speed as a "speed range other than the predetermined speed" and either the automatic setting mode or the manual setting mode. Therefore, the driver can select and assign either the automatic setting mode or the manual setting mode to the demarcation speed as a "speed range other than the predetermined speed" by operating either the automatic setting mode or the manual setting mode touch switch 50A, 50B corresponding to the demarcation speed as a "speed range other than the predetermined speed."Therefore, as in the case of the aforementioned section speed as a "predetermined speed," the operation of selecting either the automatic setting mode or the manual setting mode by the mode selection unit 42 for this section speed as a "speed range other than the predetermined speed" is performed based on the driver's operation on the operation unit 26.

[0020] 2B illustrates a state in which either the automatic setting mode or manual setting mode touch switch 48A, 48B or either the manual setting mode touch switch 50A, 50B is operated. In the figure, hatched switches indicate an operated state (selected state), while unhatched switches indicate an unoperated state (non-selected state). Specifically, the selected touch switch is displayed in inverted, or the selected touch switch is displayed in a different color from the non-selected touch switch. Therefore, in the example of FIG. 2B, if 30 km / h, 40 km / h, or 60 km / h is recognized as a road sign speed limit among the "predetermined speed" zone speeds, the autospeed speed limit setting unit 40 sets the autospeed control unit 36 ​​to the manual setting mode. Furthermore, when 80 km / h, 100 km / h, or 120 km / h of the demarcation speeds as the "predetermined speeds" are recognized as road sign speed limits, the autospeed speed limit setting unit 40 sets the autospeed control unit 36 ​​to the automatic setting mode. Furthermore, when a demarcation speed as the "speed range other than the predetermined speeds" is recognized as the road sign speed limit, the autospeed speed limit setting unit 40 sets the autospeed control unit 36 ​​to the manual setting mode.

[0021] When the autospeed speed limit setting unit 40 is set to the manual setting mode, the notification unit 44 plays and outputs from the speaker 28 a voice announcement that prompts the driver to manually operate the operation unit 26, in other words, a voice announcement that prompts the driver to accept the operation. Specifically, when the autospeed speed limit setting unit 40 is set to the manual setting mode, if the road sign speed limit recognized by the sign recognition unit 38 is a road sign speed limit that is different from the currently set set speed limit and corresponds to one of the zone speeds set in the manual setting mode, the notification unit 44 plays a voice announcement from the speaker 28, such as "A road sign with a speed limit of 40 km / h has been recognized. Would you like to change the set speed limit to 40 km / h?" If the driver is prompted by this voice announcement and determines that a change to the set speed limit is necessary, the driver operates the operation unit 26, such as operating the change acceptance switch 52A to accept the change to the set speed limit, as shown in FIG. 3 . Furthermore, if the driver determines after hearing the audio announcement that the set speed limit does not need to be changed, he or she operates the operation unit 26, such as by operating the change rejection switch 52B, which rejects the change to the set speed limit, as shown in FIG. 3 . The driver can determine whether or not the set speed limit needs to be changed by visually checking the presence or absence of road signs and road sign speed limits on the road on which the vehicle is traveling, other roads branching off from the road, or other roads adjacent to the road. The notification unit 44 is not limited to outputting an audio announcement to prompt the driver to manually operate the operation unit 26. For example, the notification unit 44 may flash the change acceptance switch 52A displayed on the display unit 24, or the manual setting mode touch switch 48B, thereby providing a notification prompting the driver to manually operate the operation unit 26.

[0022] Furthermore, when the autospeed speed limit setting unit 40 is set to the automatic setting mode, the notification unit 44 plays a voice announcement such as "A road sign with a speed limit of 40 km / h has been recognized." After that, after the set speed limit is changed by the autospeed speed limit setting unit 40 and set in the autospeed control unit 36, the notification unit 44 plays a voice announcement such as "The set speed limit has been changed to 40 km / h" from the speaker 28 to notify the driver that the set speed limit has been changed.

[0023] The display control unit 46 controls the display of various information displayed on the display unit 24. In this embodiment, the display control unit 46 has a function to display information related to ACC control on the display unit 24, as described below. FIG. 3 shows an example of the display of the meter display 32 constituting the display unit 24, in which the manual setting mode is set in the autospeed speed limit setting unit 40. As shown in FIG. 3, the meter display 32 displays a speedometer 54, as well as a road sign display unit 56 that displays icons of road signs recognized by the sign recognition unit 38, and a set speed limit display unit 58 that displays the currently set set speed limit value and an arrow. In the example of FIG. 3, the road sign display unit 56 displays the icon of the road sign (60 km / h) recognized by the sign recognition unit 38, but also displays icons of other road signs such as no entry signs and stop signs.

[0024] The meter display 32 also displays a change acceptance switch 52A that is operated when the driver, having heard the audio announcement played by the notification unit 44, agrees to set the recognized road sign speed limit as the set speed limit. The meter display 32 also displays a change rejection switch 52B that is operated when the driver, having heard the audio announcement played by the notification unit 44, refuses to set the recognized road sign speed limit as the set speed limit.

[0025] 4 is an example of the display on the meter display 32 constituting the display unit 24, showing a case where the automatic setting mode is set in the autospeed speed limit setting unit 40. As shown in FIG. 4, the meter display 32 displays a speedometer 54, a road sign display unit 56, and a set speed limit display unit 58, similar to FIG. 3. In addition, a change confirmation display unit 60 is displayed, which displays text such as "Set vehicle speed has been changed," to indicate that the recognized road sign speed limit has automatically been set as the set speed limit.

[0026] Next, the operation of the vehicle driving assistance device 10 will be described with reference to the flowchart of FIG. 5 . For convenience, in FIG. 5 , the demarcation speed as a "predetermined speed" is referred to as a "demarcation speed," and the demarcation speed as a "speed range other than the predetermined speed" is referred to as an "other demarcation speed." As shown in FIG. 2B , it is assumed that either the automatic setting mode or the manual setting mode is set for each demarcation speed as a "predetermined speed," and that either the automatic setting mode or the manual setting mode is set for the demarcation speed as a "speed range other than the predetermined speed" (other demarcation speed). While the host vehicle is traveling in ACC mode, the driving assistance ECU 30 repeatedly executes the process of FIG. 5 . First, it determines whether the sign recognition unit 38 recognizes a road sign speed limit based on image information captured by the front camera 16 (step S10). If step S10 is negative, the process returns to step S10. If step S10 is positive, it determines whether the recognized road sign speed limit is the same as the set speed limit currently set in the auto speed control unit 36 ​​(step S12). If step S12 is positive, there is no need to change the set speed limit, and the process returns to step S10. If step S12 is negative, it is determined whether the recognized road sign speed limit corresponds to a "predetermined speed" or a "speed range other than the predetermined speed" (other speed limit) as shown in Figure 2 (B) (step S14). If it is determined in step S14 that the recognized speed limit corresponds to a "predetermined speed," it is determined whether the automatic setting mode or the manual setting mode is assigned to that speed limit (step S16).

[0027] If the automatic setting mode is determined to be selected in step S16, the notification unit 44 plays a voice announcement corresponding to the automatic setting mode from the speaker 28, such as "A road sign with a speed limit of 40 km / h has been recognized." After that, the road sign speed limit recognized by the autospeed speed limit setting unit 40 is set in the autospeed control unit 36 ​​as the set speed limit, and the notification unit 44 then plays a voice announcement such as "The set speed limit has been changed to 40 km / h" (step S18), and the process returns to step S10.

[0028] On the other hand, if the manual setting mode is determined to be active in step S16, the notification unit 44 plays a voice announcement corresponding to the manual setting mode from the speaker 28, such as "A road sign indicating a 40 km / h speed limit has been recognized. Would you like to change the set speed limit to 40 km / h?" (step S20). Next, it is determined whether the change acceptance switch 52A or the change rejection switch 52B has been operated (step S22). If it is determined in step S22 that the change acceptance switch 52A has been operated, the autospeed limit setting unit 40 sets the recognized road sign speed limit as the set speed limit in the autospeed control unit 36 ​​(step S24), and the process returns to step S10. If it is determined in step S22 that the change rejection switch 52B has been operated, the process returns to step S10 without setting a new set speed limit in the autospeed control unit 36. Therefore, in this case, the set speed limit remains unchanged.

[0029] If neither the change acceptance switch 52A nor the change rejection switch 52B is operated within a predetermined time after the audio announcement is played in step S20, it may be determined that the acceptance rejection switch has been operated, and the process may return to step S10. This eliminates the need for the driver to operate the change rejection switch 52B, which is advantageous in reducing the burden on the driver.

[0030] Furthermore, when it is determined in step S22 that the change rejection switch 52B has been operated and the process returns to step S10, if a road sign speed limit that is the same as the road sign speed limit previously recognized in step S10 is recognized again, the process from step S12 onwards may be skipped and the process may return to step S10. In this way, the processes in steps S20 and S22 for the road sign speed limit that is the same as the road sign speed limit rejected by the driver are skipped, so the driver does not have to hear the same voice announcement or repeat the same operation, which is advantageous in terms of improving convenience.

[0031] On the other hand, if it is determined in step S14 that the road sign speed limit recognized corresponds to a section speed as a "speed range other than the predetermined speed," it is determined whether the automatic setting mode or the manual setting mode is assigned to the section speed as a "speed range other than the predetermined speed" (step S26). If the automatic setting mode is determined in step S26, the notification unit 44 plays from the speaker 28 a voice announcement corresponding to the automatic setting mode, such as "A road sign with a speed limit of 20 km / h has been recognized." Thereafter, the road sign speed limit recognized by the autospeed speed limit setting unit 40 is set in the autospeed control unit 36 ​​as the set speed limit, and then the notification unit 44 plays a voice announcement such as "The set speed limit has been changed to 20 km / h" (step S28), and the process returns to step S10.

[0032] On the other hand, if the manual setting mode is determined to be active in step S26, the notification unit 44 causes the speaker 28 to play a voice announcement corresponding to the manual setting mode, such as "A road sign indicating a 20 km / h speed limit has been recognized. Would you like to change the set speed limit to 20 km / h?" (step S30). Next, it is determined whether the change acceptance switch 52A or the change rejection switch 52B has been operated (step S32). If it is determined in step S32 that the change acceptance switch 52A has been operated, the autospeed limit setting unit 40 sets the road sign speed limit as the set speed limit in the autospeed control unit 36 ​​(step S34), and the process returns to step S10. If it is determined in step S32 that the change rejection switch 52B has been operated, a new set speed limit is not set in the autospeed control unit 36, and the process returns to step S10. Therefore, in this case, the set speed limit is maintained without being changed. Also, as in the case of step S20, if neither the change acceptance switch 52A nor the change rejection switch 52B is operated even after a predetermined time has elapsed after the audio announcement is played in step S30, it may be determined that the acceptance rejection switch has been operated and the process may return to step S10.

[0033] As described above, the vehicle driving assistance device 10 of this embodiment controls the speed of the vehicle by the autospeed control unit 36 ​​so as to maintain a constant inter-vehicle distance from the vehicle in front, within a range that does not exceed a predetermined set speed limit; the sign recognition unit 38 recognizes the road sign speed limit of the road on which the vehicle is traveling based on road signs; and the autospeed speed limit setting unit 40 is switchable between an automatic setting mode in which the road sign speed limit is automatically set in the autospeed control unit 36 ​​as the set speed limit, and a manual setting mode in which the road sign speed limit is set in the autospeed control unit 36 ​​as the set speed limit when the driver performs an operation that consents; and is equipped with a mode selection unit 42 that selects either the automatic setting mode or the manual setting mode for each of the section speeds that divide the set speed limit into a predetermined speed range, and sets the selected mode in the autospeed speed limit setting unit 40. Therefore, by setting the demarcation speed to the manual setting mode, even if the road sign speed limit of the road on which the vehicle is traveling is, for example, 100 km / h, the sign recognition unit 38 recognizes a road sign of a road other than the road on which the vehicle is traveling, and a road sign speed limit of, for example, 40 km / h is erroneously set in the auto speed control unit 36 ​​as the set speed limit, thereby preventing the vehicle from slowing down. This prevents the set speed limit from being erroneously changed during ACC, preventing the ACC from functioning. This eliminates the need for the driver to perform the cumbersome operation of correcting an erroneously set set speed limit, which is advantageous in improving convenience. Furthermore, by setting the demarcation speed to the automatic setting mode, if the road sign speed limit of the road on which the vehicle is traveling frequently changes, for example, between 80 km / h and 100 km / h, the auto speed control unit 36 ​​automatically sets an appropriate set speed limit without driver operation. Therefore, setting the demarcation speed to the manual setting mode and the automatic setting mode respectively reduces the driver's operation during ACC, which is advantageous in improving convenience.

[0034] Furthermore, in this embodiment, when the autospeed speed limit setting unit 40 is set to the manual setting mode, an alarm unit 44 is provided that outputs a voice announcement to prompt the driver's consent. This allows the driver to set the set speed limit after reliably recognizing that the mode is manual, which is advantageous in improving convenience.

[0035] Furthermore, in this embodiment, the demarcation speed is composed of a "predetermined speed" and a "speed range other than the predetermined speed," so that a manual setting mode or an automatic setting mode can be set corresponding to each demarcation speed, which is advantageous in reducing the driver's operations during ACC or auto speed control and improving convenience. Furthermore, in this embodiment, the demarcation speed is set in units of 10 km / h, which is the same unit as the road sign speed limit specified on general road signs posted on public roads, etc., so that it is easier for the driver to grasp the demarcation speed, which is advantageous in smoothly setting the automatic setting mode or the manual setting mode for each of a plurality of selectable speed limit values ​​with different values.

[0036] (Second embodiment) Next, a second embodiment will be described. Note that in the following embodiment, the same reference numerals will be used for the description, and the same parts as in the first embodiment will be assigned the same reference numerals, and the description thereof will be omitted, and the description will focus on the different parts. In the first embodiment, a case where an automatic setting mode and a manual setting mode are set for each partition speed by setting an automatic setting mode and a manual setting mode for each partition speed was described. However, the operation of setting the automatic setting mode and the manual setting mode for each partition speed is quite time-consuming.

[0037] Therefore, in the second embodiment, the mode selection unit 42 performs a mode setting operation as follows. Referring back to FIG. 1 , the mode selection unit 42 performs an automatic mode selection operation in which, when the section speed is equal to or less than a predetermined threshold, the mode selection unit 42 sets the autospeed speed limit setting unit 40 to one of the automatic setting mode and the manual setting mode, and when the section speed exceeds the threshold, the mode selection unit 42 sets the autospeed speed limit setting unit 40 to the manual setting mode. For example, if the threshold is 60 km / h, the mode selection unit 42 sets the autospeed speed limit setting unit 40 to the manual setting mode when the identified road sign speed limit is equal to or less than 60 km / h, and sets the autospeed speed limit setting unit 40 to the automatic setting mode when the identified road sign speed limit exceeds 60 km / h. The threshold setting for the mode selection unit 42 is performed as follows. As shown in Fig. 6A, threshold selection switches 62, each showing a plurality of threshold values ​​with different values, are displayed on the display unit 24, and when the driver operates one of the threshold selection switches 62, the selected threshold is set in the mode selection unit 42, as shown in Fig. 6B. In the figure, hatched threshold selection switches 62 indicate an operated state (selected state), and unhatched threshold selection switches 62 indicate an unoperated state (non-selected state). In this case, as described in Fig. 2B, the touch switch in the selected state is displayed in inverse video, or the touch switch in the selected state is displayed in a different color from the touch switch in the non-selected state.

[0038] Next, the operation of the vehicle driving assistance device 10 of the second embodiment will be described with reference to Figures 3 and 4 and the operational flowchart shown in Figure 7. A threshold value for the zone speed (e.g., 60 km / h) is set in advance in the mode selection unit 42, and the mode selection unit 42 sets a road sign speed limit equal to or greater than the threshold value as either the automatic setting mode or the manual setting mode (in this example, the automatic setting mode) in the autospeed speed limit setting unit 40, and sets a road sign speed limit less than the threshold value as either the automatic setting mode or the manual setting mode (in this example, the manual setting mode).

[0039] While the vehicle is traveling under ACC, the driving assistance ECU 30 repeatedly executes the process shown in FIG. 7 . First, it determines whether the sign recognition unit 38 has recognized a road sign speed limit based on image information captured by the forward camera 16 (step S50). If the result of step S50 is negative, the process returns to step S50. If the result of step S50 is positive, it determines whether the recognized road sign speed limit is the same as the set speed limit currently set in the auto speed control unit 36 ​​(step S52). If the result of step S52 is positive, there is no need to change the set speed limit, so the process returns to step S50. If the result of step S52 is negative, it determines whether the recognized road sign speed limit is equal to or greater than the threshold speed for the zone (step S54). If step S54 returns a positive result, i.e., if the recognized road sign speed limit is equal to or greater than the threshold section speed, the notification unit 44 causes the speaker 28 to play a voice announcement corresponding to the manual setting mode, such as, "A road sign indicating a speed limit of 60 km / h has been recognized. Would you like to change the set speed limit to 50 km / h?" (step S56). Next, it is determined whether the change acceptance switch 52A or the change rejection switch 52B shown in FIG. 3 has been operated (step S58). If it is determined in step S58 that the change acceptance switch 52A has been operated, the autospeed limit setting unit 40 sets the road sign speed limit as the set speed limit in the autospeed control unit 36 ​​(step S60), and the process returns to step S50. If it is determined in step S58 that the change rejection switch 52B has been operated, a new road sign speed limit is not set in the autospeed control unit 36, and the process returns to step S50. Therefore, in this case, the set speed limit is maintained without being changed. On the other hand, if the result in step S54 is negative, i.e., if it is determined that the recognized road sign speed limit is less than the threshold value, the notification unit 44 will play an audio announcement from the speaker 28 corresponding to the automatic setting mode, for example, "A road sign with a speed limit of 40 km / h has been recognized."Then, the autospeed speed limit setting unit 40 sets the road sign speed limit as the set speed limit in the autospeed control unit 36, and then the notification unit 44 plays a voice announcement such as "The set speed limit has been changed to 40 km / h" (step S62), and the process returns to step S50.

[0040] According to the second embodiment, the automatic setting mode and the manual setting mode for the zone speed are set based on a single zone speed threshold. This eliminates the need to set the automatic setting mode and the manual setting mode for each zone speed, as compared to the first embodiment. This is advantageous in significantly reducing the burden on the driver and improving convenience. While the threshold may be a fixed value set in advance, setting the zone speed threshold in the mode selection unit 42 through the driver's operation, as in the second embodiment, is advantageous in that the threshold can be flexibly set according to the driver's intentions, which is more advantageous in improving convenience. Furthermore, when the autospeed speed limit setting unit 40 automatically selects the manual setting mode through the automatic mode selection operation of the mode selection unit 42, the notification unit 44 is provided to prompt the driver to accept the operation. This allows the driver to reliably recognize that the manual setting mode is selected before setting the set speed limit, which is advantageous in improving convenience.

[0041] This application is based on a Japanese patent application (Patent Application No. 2023-203010) filed on November 30, 2023, the contents of which are incorporated herein by reference.

[0042] According to the present invention, it is possible to provide a vehicle driving assistance device that is advantageous in reducing the driver's operations and improving convenience. The present invention that achieves this effect is useful for vehicle driving assistance devices.

[0043] REFERENCE SIGNS LIST 10 Vehicle driving assistance device 12 Vehicle speed sensor 14 Forward radar 16 Forward camera 18 Engine ECU 20 Transmission ECU 22 Brake ECU 24 Display unit 26 Operation unit 28 Speaker 30 Driving assistance ECU 32 Meter display 34 Touch panel 36 Autospeed control unit 38 Sign recognition unit 40 Autospeed speed limit setting unit 42 Mode selection unit 44 Notification unit 46 Display control unit 48A, 48B Touch switches 50A, 50B Touch switches 52A Change acceptance switch 52B Change rejection switch 54 Speedometer 56 Road sign display unit 58 Set speed limit display unit 60 Change confirmation display unit 62 Threshold selection switch

Claims

1. A vehicle driving assistance device comprising: an autospeed control unit which controls the speed of the vehicle within a range not exceeding a predetermined set speed limit; a sign recognition unit which recognizes the road sign speed limit of a road on which the vehicle is traveling based on road signs; and an autospeed speed limit setting unit which is configured to be switchable between an automatic setting mode which automatically sets the road sign speed limit as the set speed limit of the autospeed control unit and a manual setting mode which sets the road sign speed limit as the set speed limit of the autospeed control unit when the driver performs an operation that agrees with the automatic setting mode; and further comprising a mode selection unit which selects either the automatic setting mode or the manual setting mode for each section speed which divides the set speed limit into a predetermined speed range, and sets the selected mode in the autospeed speed limit setting unit.

2. The vehicle driving assistance device according to claim 1, characterized in that the section speed is composed of a predetermined speed and a speed range other than the predetermined speed.

3. The vehicle driving assistance device according to claim 1 or 2, characterized in that the section speed is determined in units of 10 km / h.

4. A vehicle driving assistance device as claimed in any one of claims 1 to 3, characterized in that the mode selection unit performs an automatic mode selection operation to set one of the automatic setting mode and the manual setting mode in the autospeed speed limit setting unit when the section speed is equal to or lower than a predetermined threshold value, and to set the other of the automatic setting mode and the manual setting mode in the autospeed speed limit setting unit when the section speed exceeds the threshold value.

5. The vehicle driving assistance device according to claim 4, wherein the threshold value is set in the mode selection unit by an operation of the driver.

6. The vehicle driving assistance device according to claim 4 or 5, further comprising a notification unit that prompts the driver to perform an operation to accept the operation when the autospeed speed limit setting unit automatically selects the manual setting mode.

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