Driving assistance device and processing method for driving assistance device

Abstract

To appropriately set a set vehicle speed for roundabout traveling of a vehicle.SOLUTION: A driving support apparatus, capable of executing vehicle speed support control for allowing a vehicle to travel at a set vehicle speed which has been set in advance, includes: an entrance width acquisition unit for acquiring an entrance width of a roundabout in front of the vehicle on the basis of a captured image by a front camera of the vehicle, or position information on the vehicle and map information; an other vehicle passage time calculation unit for calculating a passage time for an other vehicle traveling in the roundabout to pass through the entrance width on the basis of the captured image by the front camera; a vehicle speed estimation unit for estimating a vehicle speed of the other vehicle on the basis of the entrance width and the passage time; and a vehicle speed setting unit for setting the set vehicle speed for roundabout traveling of the vehicle on the basis of the vehicle speed of the other vehicle.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a driving assistance device and a processing method for the driving assistance device. [Background technology]

[0002] A known technical document relating to a driving assistance device is Japanese Patent No. 5221959. This document discloses a device that performs deceleration control when entering a roundabout (circular intersection) in consideration of the curvature of the roundabout. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5221959 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned device does not have a function for controlling the vehicle speed after entering a roundabout, and the driver is required to control the vehicle speed after entering the roundabout. However, controlling the vehicle speed in a roundabout is not easy. Driving through the roundabout at the same speed that the vehicle slowed down when entering the roundabout may cause congestion. Meanwhile, other vehicles often drive at a slower speed than usual in order to immediately exit the roundabout. If the vehicle returns to the normal cruise control speed setting and attempts to drive through the roundabout, it may unintentionally approach other vehicles ahead, which is inappropriate. [Means for solving the problem]

[0005] One aspect of the present invention is a driving assistance device that performs vehicle speed assistance control to cause a vehicle to travel at a predetermined set vehicle speed, and includes an entrance width acquisition unit that acquires the entrance width of a roundabout in front of the vehicle based on an image captured by a front camera of the vehicle or vehicle position information and map information; an other vehicle passing time calculation unit that calculates the passing time for another vehicle traveling through the roundabout to pass the entrance width based on the image captured by the front camera; a vehicle speed estimation unit that estimates the vehicle speed of the other vehicle in the roundabout based on the entrance width and the passing time; and a vehicle speed setting unit that sets a set vehicle speed for the vehicle to travel through the roundabout based on the vehicle speed of the other vehicle.

[0006] In a driving assistance device according to one aspect of the present invention, the entrance width acquisition unit may acquire the curvature of the roundabout, and if the road on which the vehicle is traveling has four or more lanes and the curvature of the roundabout is equal to or greater than a certain value, may acquire the sum of the lane widths of the two lanes closest to the center of the road as the entrance width.

[0007] Another aspect of the present invention is a processing method for a driving assistance device that executes vehicle speed assistance control to cause a vehicle to travel at a preset set vehicle speed, and obtains the entrance width of a roundabout in front of the vehicle based on an image captured by a front camera of the vehicle or based on vehicle position information and map information, calculates the passing time it takes for another vehicle traveling through the roundabout to pass the entrance width based on the image captured by the front camera, estimates the vehicle speed of the other vehicle based on the entrance width and the passing time, and sets a set vehicle speed for the vehicle to travel through the roundabout based on the vehicle speed of the other vehicle. [Effects of the Invention]

[0008] According to one aspect and another aspect of the present invention, it is possible to appropriately set a set vehicle speed for a vehicle traveling through a roundabout. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a driving assistance device according to an embodiment; [Figure 2] FIG. 1 is a diagram illustrating an example of a situation when a vehicle approaches a roundabout. [Figure 3] 10 is a flowchart illustrating an example of a process for setting a vehicle speed for traveling through a roundabout. [Figure 4] 10 is a flowchart illustrating an example of an entrance width acquisition process for a multi-lane vehicle; DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] The driving assistance device 100 shown in Fig. 1 is a device that is mounted on a vehicle and is capable of executing driving assistance for the vehicle. The driving assistance device 100 executes vehicle speed assistance control as driving assistance. The vehicle speed assistance control is a control that controls the vehicle speed so that it becomes a preset vehicle speed according to the driving environment of the vehicle. The vehicle speed assistance control may be CC (Cruise Control) or ACC (Adaptive Cruise Control).

[0012] [Configuration of driving assistance device] The configuration of the driving assistance device 100 will be described below with reference to Fig. 1. The driving assistance device 100 includes a driving assistance ECU 10 (ECU: Electronic Control Unit). The driving assistance ECU 10 is an electronic control unit having a CPU (Central Processing Unit) and a storage unit such as a ROM (Read Only Memory) or a RAM (Random Access Memory). The driving assistance ECU 10 realizes various functions by, for example, executing programs stored in the storage unit by the CPU. The driving assistance ECU 10 may be composed of multiple electronic units.

[0013] The driving assistance ECU 10 is connected to a GNSS receiver 1 (GNSS: Global Navigation Satellite System), a front camera 2, an internal sensor 3, a map database 4, and an actuator 5.

[0014] The GNSS receiver 1 measures the position of the vehicle (for example, the latitude and longitude of the vehicle) by receiving signals from positioning satellites. The GNSS receiver 1 transmits the measured vehicle position information to the driving assistance ECU 10.

[0015] The front camera 2 is an imaging device that captures an image of the external situation in front of the vehicle. The front camera 2 is provided, for example, on the back side of the windshield of the vehicle, and captures an image in front of the vehicle. The front camera 2 transmits the captured image of the area in front of the vehicle to the driving assistance ECU 10. The front camera may be a monocular camera or a stereo camera.

[0016] The internal sensor 3 is a detection device that detects the running state of the vehicle. The internal sensor 3 includes a vehicle speed sensor. The vehicle speed sensor is a detector that detects the speed of the vehicle. As the vehicle speed sensor, for example, a wheel speed sensor is used that is provided on a wheel of the vehicle or a drive shaft that rotates integrally with the wheel and detects the rotation speed of the wheel. The vehicle speed sensor transmits the detected vehicle speed information (wheel speed information) to the driving assistance ECU 10.

[0017] The internal sensor 3 may include an acceleration sensor and a yaw rate sensor. The acceleration sensor is a detector that detects the acceleration of the vehicle. The acceleration sensor includes, for example, a longitudinal acceleration sensor that detects the acceleration in the longitudinal direction of the vehicle and a lateral acceleration sensor that detects the lateral acceleration of the vehicle. The acceleration sensor transmits, for example, vehicle acceleration information to the ECU 10. The yaw rate sensor is a detector that detects the yaw rate (rotational angular velocity) around the vertical axis of the center of gravity of the vehicle. For example, a gyro sensor can be used as the yaw rate sensor. The yaw rate sensor transmits the detected yaw rate information of the vehicle to the driving assistance ECU 10.

[0018] The map database 4 is a database that stores map information. The map database 4 is formed, for example, in a storage device such as an HDD (Hard Disk Drive) mounted on the vehicle. The map information includes location information of roads and intersections. The map information may include at least one of road type (road classification) information, road width information, and lane width information. Road types are regulated, for example, by law, and lane widths may be predetermined according to the type (see, for example, Article 5, Paragraph 4 of the Japanese Road Structure Regulations). In other words, even if lane width information is not included in the map information, the lane width can be determined from the road type. In addition, the map information may include curvature information of roundabouts.

[0019] The actuators 5 are devices used to control the vehicle. The actuators 5 include at least a drive actuator and a brake actuator. The drive actuator controls the amount of air supplied to the engine (throttle opening) in response to a control signal from the driving assistance ECU 10, thereby controlling the driving force of the vehicle. If the vehicle is a hybrid vehicle (HEV: Hybrid Electric Vehicle), in addition to the amount of air supplied to the engine, a control signal from the driving assistance ECU 10 is input to a motor serving as a power source to control the driving force. If the vehicle is an electric vehicle (BEV: Battery Electric Vehicle), a control signal from the driving assistance ECU 10 is input to a motor serving as a power source to control the driving force. In these cases, the motor serving as a power source constitutes the actuator 5.

[0020] The brake actuator controls the brake system in response to a control signal from the driving assistance ECU 10, and controls the braking force applied to the wheels of the vehicle. For example, a hydraulic brake system can be used as the brake system. The actuator 5 may include a steering actuator.

[0021] Next, a description will be given of the functional configuration of the driving assistance ECU 10. As shown in Fig. 1, the driving assistance ECU 10 has a roundabout detection unit 11, an entrance width acquisition unit 12, an other vehicle passing time calculation unit 13, a vehicle speed estimation unit 14, a vehicle speed setting unit 15, and a driving assistance unit 16. Some of the functions of the driving assistance ECU 10 described below may be executed by a server that can communicate with the vehicle.

[0022] The roundabout detection unit 11 detects a roundabout ahead of the vehicle based on the image captured by the front camera 2. The roundabout detection unit 11 detects the roundabout by, for example, pattern matching using an image pattern associated with the roundabout.

[0023] The roundabout detection unit 11 may detect a roundabout ahead of the vehicle based on the vehicle position information measured by the GNSS receiving unit 1 and the map information in the map database 4. The vehicle position information is not limited to the measurement results of the GNSS receiving unit 1, and may also be obtained by SLAM (Simultaneous Localization and Mapping) or dead reckoning.

[0024] When the roundabout detection unit 11 detects a roundabout ahead of the vehicle, the entrance width acquisition unit 12 acquires the entrance width of the roundabout based on the image captured by the front camera 2.

[0025] FIG. 2 is a diagram showing an example of a situation when a vehicle approaches a roundabout. FIG. 2 shows vehicle M, roundabout R, road L connected to roundabout R, and another vehicle N. Road L is a two-lane road consisting of a driving lane LA in which vehicle M is traveling and an oncoming lane LB. The connecting portion between road L and roundabout R is the entrance portion of roundabout R as seen from vehicle M. Another vehicle N is a vehicle traveling within roundabout R. As shown by the arrow in FIG. 2, other vehicle N continues traveling after passing the entrance portion of roundabout R as seen from vehicle M.

[0026] 2 also shows the lane width Wa of the driving lane LA, the lane width Wb of the oncoming lane LB, and the entrance width W, which is the width of the entrance portion of the roundabout R. The entrance width W in FIG. 2 is equal to, for example, the sum of the lane width Wa and the lane width Wb.

[0027] The entrance width acquisition unit 12 acquires the entrance width W of the roundabout R, for example, by recognizing white lines in the captured image. The entrance width acquisition unit 12 may also recognize the number of lanes and the lane widths of the road L by recognizing the white lines. The entrance width acquisition unit 12 calculates the lane width Wa of the driving lane LA and the lane width Wb of the oncoming lane LB, and thereby acquires the entrance width W as the sum of the lane widths Wa and Wb. Note that the entrance width acquisition unit 12 may also directly acquire the entrance width W as the width of the road L by recognizing the white lines, without calculating the lane widths.

[0028] The entrance width acquisition unit 12 may acquire the entrance width W of the roundabout R based on the position information of the vehicle M and map information. The map information includes information on the number of lanes and lane widths of the road L, or information on the road width of the road L. The lane width may be calculated from the road type information of the road L included in the map information, using lane width information predetermined according to the road type by law. The entrance width acquisition unit 12 acquires the entrance width W by acquiring the lane width Wa of the traveling lane LA and the lane width Wb of the oncoming lane LB from the map information. The entrance width acquisition unit 12 may acquire the road width of the road including the traveling lane LA as the entrance width W. Note that the road L connecting to the roundabout R is not limited to having two lanes, but may have one lane or four or more lanes.

[0029] The entrance width acquisition unit 12 may acquire the curvature of the roundabout R and adjust the entrance width W using the curvature of the roundabout R. The curvature of the roundabout R is acquired, for example, from an image captured by the front camera 2. The curvature of the roundabout R may be acquired from map information or from a traffic information server of a public institution or the like.

[0030] The entrance width acquisition unit 12 performs a predetermined calculation so that the entrance width W is longer by, for example, the curvature of the roundabout R. By taking the curvature of the roundabout R into consideration, the entrance width acquisition unit 12 can improve the accuracy of estimating the vehicle speed of another vehicle N that is traveling while turning within the roundabout R. The entrance width acquisition unit 12 may also adjust the lane width according to the curvature of the roundabout R.

[0031] When the road L has four or more lanes and the curvature of the roundabout R is equal to or greater than a certain value, the entrance width acquisition unit 12 may acquire the entrance width W by using only the two lanes closest to the center of the road as the entrance of the road L to the roundabout R. In other words, of the four or more lanes that make up the road L, lanes other than the two lanes closest to the center of the road are not treated as the entrance of the road L to the roundabout R. In this case, the entrance width W is the sum of the lane widths of the two lanes closest to the center of the road. When the road L has four or more lanes, the accuracy of estimating the vehicle speed of another vehicle N, which will be described later, can be improved by using only the two lanes closest to the center of the road, which are less affected by the curvature of the roundabout R.

[0032] The other vehicle passing time calculation unit 13 calculates the passing time for the other vehicle N traveling through the roundabout R to pass the entrance width W based on the image captured by the front camera 2. The other vehicle passing time calculation unit 13 calculates the passing time based on the acquisition time of the captured image and image recognition processing. The passing time is, for example, the time from when the front end of the other vehicle N reaches between the white lines that make up the entrance width W on the captured image to when the entire other vehicle N passes between the white lines.

[0033] The other vehicle passing time calculation unit 13 may calculate the lane width passing time of the other vehicle N for each of the lane width Wa of the traveling lane LA and the lane width Wb of the oncoming lane LB. The lane width passing time is, for example, the time it takes for the leading edge of the other vehicle N to pass between the white lines that make up the traveling lane LA on the captured image. The sum of the lane width passing time of the traveling lane LA and the lane width passing time of the oncoming lane LB corresponds to the above passing time. When the road L has four or more lanes, the other vehicle passing time calculation unit 13 calculates the lane width passing times corresponding to all the lanes.

[0034] The vehicle speed estimation unit 14 estimates the vehicle speed of the other vehicle N traveling through the roundabout R based on the entrance width W acquired by the entrance width acquisition unit 12 and the passing time calculated by the other vehicle passing time calculation unit 13. The vehicle speed estimation unit 14 estimates the vehicle speed of the other vehicle N, for example, by dividing the entrance width W by the passing time. When the vehicle speed estimation unit 14 is able to capture images of multiple other vehicles passing through the entrance portion of the roundabout R, it estimates the vehicle speeds of the multiple other vehicles.

[0035] When the lane width passing time of the other vehicle N has been calculated for each of a plurality of lanes, the vehicle speed estimation unit 14 estimates a lane-specific vehicle speed, which is the vehicle speed of the other vehicle N estimated for each lane. The vehicle speed estimation unit 14 estimates the lane-specific vehicle speed of the other vehicle N in the traveling lane LA by dividing the lane width Wa of the traveling lane LA by the lane width passing time corresponding to the traveling lane LA. The vehicle speed estimation unit 14 estimates, for example, the average value of the lane-specific vehicle speeds as the vehicle speed of the other vehicle N at the entrance portion of the roundabout R.

[0036] The vehicle speed estimation unit 14 may weight the lane-adjusted vehicle speed of the other vehicle N estimated in the driving lane LA more heavily than the lane-adjusted vehicle speed of the other vehicle N estimated in other lanes. The heavier the weighting, the greater the influence on the final estimation result of the vehicle speed of the other vehicle N. The further away from the front of the vehicle M the other vehicle N is, the more likely it is that the accuracy of the position of the other vehicle N that can be recognized from the image captured by the front camera 2 will decrease. For this reason, the vehicle speed estimation unit 14 can increase the accuracy of the final estimation of the vehicle speed of the other vehicle N by weighting the lane-adjusted vehicle speed of the other vehicle N crossing the driving lane LA in front of the vehicle M. The vehicle speed estimation unit 14 may directly estimate the lane-adjusted vehicle speed of the other vehicle N estimated in the driving lane LA as the vehicle speed of the other vehicle N at the entrance portion of the roundabout R.

[0037] When the road L on which the vehicle M is traveling has four or more lanes, the vehicle speed estimation unit 14 may weight the lane-specific vehicle speed of the other vehicle N estimated in the two lanes closest to the center of the road more heavily than the lane-specific vehicle speed of the other vehicle N estimated in the other lanes. By weighting the lane-specific vehicle speed of the other vehicle N estimated in the two lanes closest to the center of the road, which are less affected by the curvature of the roundabout R, the accuracy of the final estimation of the vehicle speed of the other vehicle N can be improved. The vehicle speed estimation unit 14 may directly estimate the average value of the vehicle speeds of the other vehicle N estimated in the two lanes closest to the center of the road as the vehicle speed of the other vehicle N at the entrance portion of the roundabout R. Note that when the road L on which the vehicle M is traveling has four or more lanes and only the two lanes closest to the center of the road are used as the entrance to the roundabout R, the processing in this paragraph does not need to be performed.

[0038] The vehicle speed setting unit 15 sets a set vehicle speed for vehicle M to travel through a roundabout based on the vehicle speeds of other vehicles (including other vehicle N) estimated by the vehicle speed estimation unit 14. When the vehicle speeds of multiple other vehicles have been estimated, the vehicle speed setting unit 15 sets the average value of the vehicle speeds of the multiple other vehicles as the set vehicle speed for travel through a roundabout. When the vehicle speed of only one other vehicle N has been estimated, the vehicle speed setting unit 15 may set the vehicle speed of the other vehicle N as the set vehicle speed for travel through a roundabout.

[0039] The vehicle speed setting unit 15 may set the set vehicle speed for traveling through the roundabout to the average value of the vehicle speeds of multiple other vehicles or the vehicle speed of only one other vehicle N minus a certain speed. A median value may be used instead of the average value.

[0040] The driving assistance unit 16 executes vehicle speed assistance control of the vehicle M. The set vehicle speed of the vehicle speed assistance control before approaching the roundabout R is set to set vehicle speed Va. The driving assistance unit 16 controls the vehicle speed of the vehicle M by sending a control signal to the actuator 5.

[0041] When the roundabout detection unit 11 detects a roundabout R ahead of the vehicle M while the vehicle speed assistance control is being executed, the driving assistance unit 16 decelerates the vehicle M to an entry speed Vb. The entry speed Vb is a speed that is preset for entering the roundabout R.

[0042] The driving assistance unit 16 decelerates the vehicle speed of the vehicle M to an entry speed Vb just before the entrance to the roundabout R. When a set vehicle speed Vc for traveling through a roundabout is set by the vehicle speed setting unit 15, the entry speed Vb may be adjusted to be a speed lower than the set vehicle speed Vc for traveling through a roundabout. Note that, when a stop line is present just before the roundabout R, the driving assistance unit 16 makes the vehicle M stop temporarily.

[0043] When vehicle M enters roundabout R, driving assistance unit 16 executes vehicle speed assistance control at set vehicle speed Vc for traveling through the roundabout set by vehicle speed setting unit 15. Driving assistance unit 16 causes vehicle M to travel at a constant speed at set vehicle speed Vc through roundabout R. When the inter-vehicle distance between vehicle M and the preceding vehicle becomes less than the set distance, driving assistance unit 16 adjusts the vehicle speed so that the inter-vehicle distance becomes the set distance. When vehicle M exits roundabout R, driving assistance unit 16 executes vehicle speed assistance control of vehicle M so that the vehicle speed returns to the original set vehicle speed Va.

[0044] If the vehicle speed setting unit 15 is unable to set the set vehicle speed Vc for traveling through the roundabout, the driving assistance unit 16 may enter the roundabout R while traveling at a constant speed at the approach speed Vb. Thereafter, the driving assistance unit 16 may accelerate the vehicle M to a set vehicle speed Vd (fixed value) that is predetermined as a temporary set vehicle speed for traveling through the roundabout, and travel at a constant speed within the roundabout R. When the vehicle M exits the roundabout R, the driving assistance unit 16 executes vehicle speed assistance control of the vehicle M so that the vehicle speed returns to the original set vehicle speed Va. The driving assistance unit 16 may execute automatic stopping and automatic starting according to the inter-vehicle distance between the preceding vehicle and the vehicle M.

[0045] [Method for handling driving assistance devices] Next, a processing method of the driving assistance device 100 according to this embodiment will be described. Fig. 3 is a flowchart showing an example of a vehicle speed setting process for driving around a roundabout. The vehicle speed setting process for driving around a roundabout is performed when vehicle speed assistance control of the vehicle M is being executed.

[0046] 3, in step S10, the driving assistance ECU 10 of the driving assistance device 100 detects a roundabout R ahead of the vehicle using the roundabout detection unit 11. The roundabout detection unit 11 detects the roundabout ahead of the vehicle based on an image captured by the front camera 2, for example.

[0047] If the roundabout R ahead of the vehicle is detected (S10: YES), the driving assistance ECU 10 proceeds to S11. If the roundabout R ahead of the vehicle is not detected (S10: NO), the driving assistance ECU 10 ends the vehicle speed setting process for traveling through a roundabout.

[0048] In S11, the driving assistance ECU 10 causes the driving assistance unit 16 to decelerate the vehicle M to the approach speed Vb. Thereafter, the driving assistance ECU 10 proceeds to S12.

[0049] In S12, the driving assistance ECU 10 determines whether or not the entrance width W of the roundabout R has been acquired by the entrance width acquisition unit 12. The entrance width acquisition unit 12 acquires the entrance width W of the roundabout R, for example, by recognizing white lines in the captured image. The entrance width acquisition unit 12 may acquire the entrance width W of the roundabout R based on position information of the vehicle M and map information.

[0050] If the driving assistance ECU 10 determines that the entrance width W of the roundabout R has been acquired (S12: YES), the process proceeds to S13. If the driving assistance ECU 10 does not determine that the entrance width W of the roundabout R has been acquired (S12: NO), the driving assistance ECU 10 ends the vehicle speed setting process for traveling through the roundabout. If it is determined that the entrance width W of the roundabout R has not been acquired, this may be the case when the front camera 2 is unable to capture an image of the entrance to the roundabout R due to the presence of a large preceding vehicle, for example.

[0051] In S13, the driving assistance ECU 10 determines whether the other vehicle passing time calculation unit 13 has calculated the passing time for the other vehicle N traveling through the roundabout R to pass the entrance width W. The other vehicle passing time calculation unit 13 calculates the passing time based on the image captured by the front camera 2. If the driving assistance ECU 10 determines that the passing time has been calculated (S13: YES), the driving assistance ECU 10 proceeds to S14. If the driving assistance ECU 10 does not determine that the passing time has been calculated (S13: NO), the driving assistance ECU 10 ends the vehicle speed setting process for traveling through the roundabout. If it is determined that the passing time has not been calculated, this occurs when, for example, no other vehicle traveling through the roundabout R has been captured.

[0052] In S14, the driving assistance ECU 10 calculates the average vehicle speed of other vehicles traveling through the roundabout R using the vehicle speed estimation unit 14. The number of other vehicles is not limited to one. The vehicle speed estimation unit 14 estimates the vehicle speed of the other vehicle by, for example, dividing the entrance width W by the passing time. Thereafter, the driving assistance ECU 10 proceeds to S15.

[0053] In S15, the driving assistance ECU 10 sets a set vehicle speed for traveling through a roundabout using the vehicle speed setting unit 15. The vehicle speed setting unit 15 sets, for example, an average value of the vehicle speeds of other vehicles traveling through the roundabout R as the set vehicle speed for traveling through a roundabout for the vehicle M. Thereafter, the driving assistance ECU 10 ends the vehicle speed setting process for traveling through a roundabout.

[0054] 4 is a flowchart showing an example of the entrance width acquisition process for a multi-lane vehicle. The entrance width acquisition process is executed, for example, between S10 and S12 in FIG.

[0055] 4, in S20, the driving assistance ECU 10 acquires the curvature of the roundabout R from the entrance width acquisition unit 12. The curvature of the roundabout R is acquired from, for example, an image captured by the front camera 2 or map information. The driving assistance ECU 10 proceeds to S21.

[0056] In S21, the driving assistance ECU 10 determines whether the road on which the vehicle M is traveling has four or more lanes using the entrance width acquisition unit 12. The entrance width acquisition unit 12 recognizes the number of lanes on the road L by recognizing white lines. If the driving assistance ECU 10 determines that the road on which the vehicle M is traveling has four or more lanes (S21: YES), the driving assistance ECU 10 proceeds to S22. If the driving assistance ECU 10 does not determine that the road on which the vehicle M is traveling has four or more lanes (S21: NO), the driving assistance ECU 10 ends the entrance width acquisition process for multi-lane traffic.

[0057] In S22, the driving assistance ECU 10 determines whether the curvature of the roundabout R is equal to or greater than a certain value using the entrance width acquisition unit 12. If the driving assistance ECU 10 determines that the curvature of the roundabout R is equal to or greater than the certain value (S22: YES), the driving assistance ECU 10 proceeds to S23. If the driving assistance ECU 10 does not determine that the curvature of the roundabout R is equal to or greater than the certain value (S22: NO), the driving assistance ECU 10 ends the entrance width acquisition process for multi-lane traffic.

[0058] In S23, the driving assistance ECU 10 acquires the entrance width W of only the two lanes near the center of the road as the entrance of the road L to the roundabout R using the entrance width acquisition unit 12. Thereafter, the driving assistance ECU 10 ends the entrance width acquisition process for multi-lane traffic.

[0059] According to the driving assistance device 100 and the processing method of the driving assistance device 100 according to the present embodiment described above, the vehicle speed of other vehicles traveling through the roundabout is estimated from the width of the entrance to the roundabout ahead of the vehicle and the time it takes for the other vehicles to pass, and the set vehicle speed for the vehicle traveling through the roundabout is set based on the vehicle speed of the other vehicles traveling through the roundabout. This makes it possible to set an appropriate set vehicle speed that is less likely to disrupt the flow of other vehicles traveling through the roundabout than when the vehicle speed of the other vehicles is not taken into consideration.

[0060] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. The present invention can be embodied in various forms, including the above-described embodiments, with various modifications and improvements made based on the knowledge of those skilled in the art.

[0061] For example, the driving assistance unit 16 does not necessarily have to decelerate the vehicle M to the entry speed Vb before entering the roundabout R. If the vehicle M has the front camera 2, it does not necessarily have to have the GNSS receiver 1 and the map database 4. Similarly, if the vehicle M has the GNSS receiver 1 and the map database 4, it does not necessarily have to have the front camera 2. [Explanation of symbols]

[0062] 1...GNSS receiver, 2...forward camera, 3...internal sensor, 4...map database, 5...actuator, 10...driving assistance ECU, 11...roundabout detection unit, 12...entrance width acquisition unit, 13...other vehicle passing time calculation unit, 14...vehicle speed estimation unit, 15...vehicle speed setting unit, 16...driving assistance unit, 100...driving assistance device, L...road, M...vehicle, N...other vehicle, R...roundabout, W...entrance width, Wa, Wb...lane width.

Claims

1. A driving assistance device that performs vehicle speed assistance control to drive a vehicle at a preset vehicle speed, an entrance width acquisition unit that acquires an entrance width of a roundabout ahead of the vehicle based on an image captured by a front camera of the vehicle or based on position information and map information of the vehicle; an other vehicle passing time calculation unit that calculates a passing time for another vehicle traveling through the roundabout to pass through the entrance width based on the image captured by the front camera; a vehicle speed estimation unit that estimates a vehicle speed of the other vehicle based on the entrance width and the passing time; a vehicle speed setting unit that sets a set vehicle speed for traveling through a roundabout of the vehicle based on the vehicle speed of the other vehicle; A driving assistance device comprising:

2. the entrance width acquisition unit acquires lane widths of each of the plurality of lanes when a road on which the vehicle heading toward the roundabout is traveling has a plurality of lanes; the other vehicle passing time calculation unit calculates a lane width passing time for the other vehicle to pass through the lane width for each lane, 2. The driving assistance device according to claim 1, wherein the vehicle speed estimation unit estimates a lane-corresponding vehicle speed, which is the vehicle speed of the other vehicle for each lane, based on the lane widths and the lane width passing times of the plurality of lanes, and estimates the vehicle speed of the other vehicle traveling through the roundabout from the lane-corresponding vehicle speed of the other vehicle.

3. The driving assistance device according to claim 1 , wherein the entrance width acquisition unit acquires a curvature of the roundabout and adjusts the entrance width using the curvature of the roundabout.

4. 3. The driving assistance device according to claim 2, wherein the entrance width acquisition unit acquires a curvature of the roundabout, and when a road on which the vehicle is traveling has four or more lanes and the curvature of the roundabout is equal to or greater than a certain value, acquires the entrance width by considering only two lanes closer to the center of the road as an entrance to the road of the roundabout.

5. A processing method of a driving assistance device that executes vehicle speed assistance control to drive a vehicle at a preset vehicle speed, comprising: acquiring an entrance width of a roundabout ahead of the vehicle based on an image captured by a front camera of the vehicle or position information and map information of the vehicle; calculating a passing time for another vehicle traveling through the roundabout to pass through the entrance width based on the image captured by the front camera; estimating a vehicle speed of the other vehicle based on the entrance width and the passing time; A processing method for a driving assistance device, which sets a set vehicle speed for driving the vehicle through a roundabout based on the vehicle speed of the other vehicle.

Images