Driving assistance method and driving assistance device

Abstract

A driving assistance method and driving assistance device, when accelerating a vehicle traveling at a speed below a speed limit based on a curved road to a set speed after passing through a curved road, accelerates the vehicle with a first acceleration if curve information related to the curved road is obtained, and accelerates the vehicle with a second acceleration less than the first acceleration if curve information is not obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to a driving assistance method and a driving assistance device. BACKGROUND

[0002] A driving assistance device is proposed which performs acceleration and deceleration of a vehicle to perform automatic travel control of the vehicle so that a travel parameter of the vehicle approaches a prescribed target value, and which determines a curve travel section in which the vehicle travels a curve, and prohibits acceleration in the curve travel section based on the automatic travel control (see Patent Literature 1).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2017-47710

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] The driving assistance device according to Patent Literature 1 prohibits acceleration in the curve travel section based on the automatic travel control on the premise that the curve travel section is determined, and thus, in a case where curve information related to a curve road on a road cannot be acquired, it can lead to abrupt acceleration of the vehicle and the like, and appropriate acceleration of the vehicle on the curve road and after passing the curve road cannot be performed. SUMMARY

[0008] The present application has been achieved in view of the above-described problems, and aims to provide a driving assistance method and a driving assistance device which can achieve appropriate acceleration of a vehicle on a curve road and after passing the curve road even in a case where curve information related to a curve road on a road cannot be acquired.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] A driving assistance method and a driving assistance device according to one embodiment of the present application, when accelerating a vehicle traveling at a vehicle speed below a limit speed of a curve road to a set speed after passing the curve road, accelerate the vehicle at a first acceleration in a case where curve information related to the curve road is acquired, and accelerate the vehicle at a second acceleration smaller than the first acceleration in a case where the curve information cannot be acquired.

[0011] EFFECT OF THE INVENTION

[0012] According to the present application, appropriate acceleration of a vehicle on a curve road and after passing the curve road can be achieved even in a case where curve information related to a curve road on a road cannot be acquired. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1This is a block diagram showing the structure of a driving assistance device according to one embodiment of the present invention.

[0014] Figure 2 This is a flowchart illustrating the processing of a driving assistance device according to one embodiment of the present invention. Detailed Implementation

[0015] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same symbols are used to refer to the same parts and the descriptions are omitted.

[0016] [Structure of driver assistance devices]

[0017] Reference Figure 1 This section describes a structural example of the driver assistance device 1. The driver assistance device 1 is mounted on the vehicle, which has an autonomous driving function. The autonomous driving function includes ACC (Adaptive Cruise Control), lane keeping assist, automatic lane changing, and automatic parking, but in this embodiment, the driver assistance device 1 is primarily used for ACC. ACC is an autonomous driving function that automatically controls the acceleration and deceleration of the vehicle to follow the vehicle in front, with a preset speed as the upper limit. It also performs lane keeping control to maintain a lane distance corresponding to the currently set speed.

[0018] Follow control also includes the control of following the vehicle ahead after detecting the vehicle ahead has started moving when stopped such as waiting at traffic lights or in traffic jams.

[0019] like Figure 1 As shown, the driver assistance device 1 includes: a camera 10, a radar 11, a sonar 12, a vehicle speed sensor 13, a GPS receiver 14, a switch 15, a controller 20, a steering actuator 30, an accelerator pedal actuator 31, and a brake actuator 32. Additionally, the driver assistance device 1 may also include a navigation device (not shown).

[0020] Multiple cameras 10 are installed in front of, to the sides of, behind, and on the side mirrors of the vehicle. Cameras 10 have imaging elements such as CCD (charge-coupled device) and CMOS (complementary metal oxide semiconductor). Cameras 10 detect objects (pedestrians, bicycles, two-wheeled vehicles, other vehicles, etc.) and surrounding information (road markings, traffic lights, signs, pedestrian crossings, intersections, etc.). Cameras 10 output the captured images to controller 20.

[0021] Multiple radars 11 are installed at the front, front side, and rear side of the vehicle. The radars 11 emit radio waves towards objects around the vehicle and measure the distance and direction of the objects by measuring the reflected waves. The radars 11 output the measured data to the controller 20.

[0022] Sonar 12 is mounted on the front bumper or front grille. Sonar 12 measures the distance and direction of objects near the vehicle (e.g., about 1-2 meters) by emitting ultrasonic waves and measuring their reflected waves. Sonar 12 outputs the measured data to controller 20.

[0023] The vehicle speed sensor 13 detects the speed of the vehicle and outputs the detected speed to the controller 20.

[0024] GPS receiver 14 detects the vehicle's position information on the ground by receiving radio waves from artificial satellites. The position information detected by GPS receiver 14 includes latitude and longitude information. Furthermore, the method for detecting the vehicle's position information is not limited to GPS receiver 14. For example, a method called ranging can also be used to estimate the position. The ranging method estimates the vehicle's position by calculating the amount and direction of movement based on the vehicle's rotation angle and angular velocity. The location where GPS receiver 14 is installed is not particularly limited; as an example, GPS receiver 14 is installed on the vehicle's dashboard. GPS receiver 14 outputs the detected position information to controller 20.

[0025] Multiple switches 15 are provided on the steering wheel. These switches 15 include switches for adjusting the set speed controlled by ACC, switches for setting the inter-vehicle distance when ACC is activated, and switches for initiating following motion when the preceding vehicle starts moving. In this embodiment, the switches 15 are described as physical switches, but are not limited thereto. The switches 15 may also be virtual switches. In the case where the switches 15 are virtual switches, they may also be displayed on the touch panel used by the navigation device.

[0026] The controller 20 is an electronic control unit (ECU) with CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), CAN (Controller Area Network) communication circuits, etc.

[0027] A computer program for functioning as a driving assistance device 1 is installed in the controller 20. By executing the computer program, the controller 20 functions as multiple information processing circuits included in the driving assistance device 1. Here, an example of implementing the multiple information processing circuits included in the driving assistance device 1 via software is shown; however, dedicated hardware for performing the various information processing operations described below can also be prepared to construct the information processing circuits. Alternatively, the multiple information processing circuits can be constructed from separate hardware components.

[0028] The controller 20 includes multiple information processing circuits, including a road shape acquisition unit 21, a curve information acquisition unit 22, a determination unit 23, an acceleration setting unit 24, and a driving control unit 25.

[0029] The road shape acquisition unit 21 acquires the shape of the road on which the vehicle travels based on images acquired from the camera 10 and information about the vehicle's surroundings acquired from the radar 11 and sonar 12. For example, the road shape acquisition unit 21 extracts dividing lines from the images acquired by the camera 10 to acquire the shape of the lane on which the vehicle travels. In addition, the road shape acquisition unit 21 can also acquire the shape of the road on which the vehicle travels from a navigation device not shown.

[0030] The curve information acquisition unit 22 calculates the radius of curvature of the road on which the vehicle travels as curve information based on the shape of the road obtained by the road shape acquisition unit 21. For example, the curve information acquisition unit 22 calculates a small change in the vehicle's posture (the direction the vehicle is facing) Δθ, assuming the vehicle has traveled a small distance Δs along the road shape, and calculates the radius of curvature by dividing Δs by Δθ. Alternatively, the curve information acquisition unit 22 may also obtain the radius of curvature of the road on which the vehicle travels as curve information from a navigation device not shown in the figure.

[0031] The curve information acquisition unit 22 can also calculate curve information by combining curve information obtained from the navigation device and curve information calculated based on the road shape. For example, before the vehicle enters a curve, the camera may not be able to capture enough of the curve, resulting in a situation where the curve information cannot be calculated with sufficient accuracy based on the road shape obtained by the road shape acquisition unit 21. In this case, the curve information acquisition unit 22 mainly obtains curve information related to the curve from the navigation device. Furthermore, when the vehicle is traveling on a curve, the curve information acquisition unit 22 mainly calculates the radius of curvature of the road on which the vehicle is traveling as curve information based on the road shape obtained by the road shape acquisition unit 21.

[0032] Furthermore, when both curve information obtained from the navigation device and curve information calculated based on the road shape are obtained, the curve information acquisition unit 22 may prioritize using the curve information calculated based on the road shape. The reason for prioritizing the use of curve information calculated based on the road shape is that, compared to curve information obtained from the navigation device, the curve information calculated based on the road shape more strongly reflects the current condition of the curve and is therefore more reliable.

[0033] When the curve information acquisition unit 22 acquires curve information, it sets the curve information acquisition status to "acquisition completed". On the other hand, when the curve information acquisition unit 22 fails to acquire curve information, it sets the curve information acquisition status to "acquisition failed".

[0034] Here, "the case where curve information is obtained" means that at least one of the curve information obtained from the navigation device and the curve information calculated based on the shape of the road is obtained. "The case where curve information is not obtained" means that neither the curve information obtained from the navigation device nor the curve information calculated based on the shape of the road is obtained.

[0035] In addition, if the accuracy of the calculated or obtained curve information exceeds the specified level, it can be treated as "the case where curve information has been obtained". On the other hand, if the accuracy of the calculated or obtained curve information is lower than the specified level, it can be treated as "the case where curve information has not been obtained".

[0036] The determination unit 23 determines whether the curve information acquisition unit 22 has acquired curve information. Specifically, the determination unit 23 refers to the curve information acquisition status of the curve information acquisition unit 22. If the acquisition status is "acquisition completed", the determination unit 23 determines that the curve information has been acquired. On the other hand, if the acquisition status is "acquisition failed", the determination unit 23 determines that the curve information has not been acquired.

[0037] In addition, the determination unit 23 can also determine whether the user riding in the vehicle has given an acceleration instruction. For example, if the user operates the accelerator or if the switch 15 that increases the set speed controlled by ACC is operated, the determination unit 23 determines that the user has given an acceleration instruction.

[0038] Furthermore, the determination unit 23 can also prevent the operation of the switch 15 that increases the set speed when the vehicle is traveling on a curved road, and determine whether there is an acceleration instruction from a user riding in the vehicle other than the operation of increasing the set speed. During the period when the vehicle is accelerating towards the set speed while traveling on a curved road, the operation of the switch 15 that increases the set speed can also be left unprepared.

[0039] Furthermore, the determination unit 23 can also determine whether the speed limit for the vehicle has been lifted. Here, "speed limit lifted" includes two concepts: "the upper limit of the vehicle's speed limit disappears" and "the speed limit increases," meaning that the upper limit of the vehicle's speed limit has been relaxed.

[0040] The determination unit 23 may also determine that "the speed limit has been lifted" if there is no "speed limit" at the time of the current determination. Alternatively, the determination unit 23 may determine "speed limit" within a predetermined cycle or in each predetermined processing step of the controller 20, and determine that "speed limit has been lifted" if the "speed limit" at the time of the current determination is greater than the "speed limit" at the time of the previous determination. In other cases, the determination unit 23 may determine that "speed limit has not been lifted".

[0041] The acceleration setting unit 24 sets the acceleration of the vehicle when it is traveling on a curved road. For example, the acceleration setting unit 24 sets a speed limit for the vehicle when it is traveling on a curved road based on the curve information, and sets the acceleration of the vehicle so that the vehicle travels on the curved road at a speed below the set speed limit.

[0042] Here, the "speed limit" can also be set based on the radius of curvature of the curve. For example, the "speed limit" set when the radius of curvature of the curve is small can be lower than the "speed limit" set when the radius of curvature of the curve is large. Furthermore, the "speed limit" can be set in multiple levels based on the radius of curvature of the curve. Moreover, the "speed limit" can also be set to a specified speed when the radius of curvature of the curve is below a specified value.

[0043] In addition, a "speed limit" can be set for the entire curved road, or the curved road can be divided into multiple sections along the vehicle's direction of travel, with different "speed limits" set for each section.

[0044] This section explains the case where a curved road is divided into multiple sections along the vehicle's direction of travel, with different "speed limits" set for each section. For example, compared to the curvature near the entrance and exit of the curve, the curvature near the center of the curve often becomes abrupt. That is, in most cases, the radius of curvature of the section near the center of the curve is shorter than that of the sections near the entrance and exit. In this case, the speed limit set in the section near the center of the curve is set lower than the speed limit set in the sections near the entrance and exit.

[0045] Therefore, in order to make the vehicle travel at a speed below the speed limit on the curved road, the acceleration setting unit 24 sets the acceleration of the vehicle so that the vehicle decelerates near the entrance of the curved road and accelerates near the exit of the curved road.

[0046] That is, as the vehicle moves from the entrance of the curve toward the center, the speed limit becomes stricter, and the vehicle gradually decelerates. Conversely, as the vehicle moves from the center of the curve toward the exit, the speed limit becomes more lenient (i.e., the speed limit is lifted), and the vehicle gradually accelerates. Furthermore, after passing through the curve, the vehicle is controlled to travel at the set speed.

[0047] Furthermore, when the vehicle decelerates to a speed below the speed limit, the acceleration setting unit 24 can refer to the determination result of the determination unit 23 and, if it is determined that curve information has not been obtained, set an acceleration to accelerate the vehicle towards the set speed. That is, if curve information cannot be obtained, the acceleration setting unit 24 can also set the acceleration in a manner that returns the vehicle to the state of traveling at the set speed.

[0048] Furthermore, when accelerating the vehicle to a set speed, the acceleration setting unit 24 can refer to the determination result of the determination unit 23 and set a first acceleration if it is determined that curve information has been obtained. On the other hand, if it is determined that curve information has not been obtained, a second acceleration smaller than the first acceleration can be set.

[0049] Furthermore, when accelerating the vehicle to a set speed, the acceleration setting unit 24 may refer to the determination result of the determination unit 23 and, if it is determined that there is an acceleration instruction from the user, set a specified acceleration (user-defined acceleration) in a manner that accelerates the vehicle based on the acceleration instruction.

[0050] The driving control unit 25 controls the vehicle to accelerate or decelerate at an acceleration set by the acceleration setting unit 24. More specifically, the driving control unit 25 controls the accelerator pedal actuator 31 and the brake actuator 32 to accelerate or decelerate the vehicle at an acceleration set by the acceleration setting unit 24. In addition, the driving control unit 25 controls the steering actuator 30 to ensure that the vehicle travels along the road shape obtained by the road shape acquisition unit 21, particularly the lane in which the vehicle is traveling.

[0051] [Processing steps for driver assistance devices]

[0052] Next, refer to Figure 2 The flowchart illustrates the processing steps of the driving assistance device in this embodiment. Figure 2The driving assistance device shown specifically indicates how the vehicle is handled when driving on a curved road, and it can also be repeatedly executed at a predetermined interval.

[0053] In step S101, the determination unit 23 determines whether the speed limit for the vehicle has been lifted.

[0054] If it is determined that the speed limit has not been lifted (in the case of "No" in step S101), in step S113, the acceleration setting unit 24 sets the acceleration of the vehicle so that the vehicle travels on the curved road at a speed below the set speed limit, and the driving control unit 25 controls the vehicle to accelerate or decelerate at the set acceleration.

[0055] If it is determined that the speed limit has been lifted (in the case of "yes" in step S101), in step S103, the determination unit 23 determines whether there is a user's acceleration instruction.

[0056] If it is determined that there is a user's acceleration instruction (if "yes" is given in step S103), in step S111, the acceleration setting unit 24 sets a user-defined acceleration, so that the vehicle accelerates based on the acceleration instruction, and the driving control unit 25 controls the vehicle to accelerate at the set acceleration.

[0057] If it is determined that there is no user acceleration instruction (the case is "No" in step S103), in step S105, the determination unit 23 determines whether the curve information acquisition unit 22 has acquired curve information.

[0058] If it is determined that curve information has been obtained (in the case of "yes" in step S105), in step S107, the acceleration setting unit 24 sets a first acceleration, and the driving control unit 25 controls the vehicle to accelerate at the first acceleration.

[0059] On the other hand, if it is determined that curve information has not been obtained (in the case of "No" in step S105), in step S109, the acceleration setting unit 24 sets a second acceleration, and the driving control unit 25 controls the vehicle to accelerate with the second acceleration.

[0060] [Effects of the Implementation Method]

[0061] As detailed above, the driving assistance method and driving assistance device of this embodiment control a controller that drives a vehicle at a set speed after it has traveled along a curved road. When the controller accelerates a vehicle traveling on a curved road at a speed below the speed limit of the curved road to the set speed, it determines whether curve information related to the curved road has been obtained. If curve information has been obtained, the vehicle is accelerated with a first acceleration. If curve information has not been obtained, the vehicle is accelerated with a second acceleration that is smaller than the first acceleration.

[0062] Therefore, even when curve information related to the curves on the road is unavailable, appropriate acceleration of the vehicle before and after passing through curves can be achieved. In particular, it can suppress sudden acceleration of the vehicle when not passing through curves, thereby reducing the likelihood of the vehicle generating sudden centrifugal force. Furthermore, it can reduce discomfort experienced by passengers and improve comfort. Moreover, as a result of suppressing sudden acceleration, it can suppress the physical load applied to the vehicle, reducing the occurrence of operational abnormalities and malfunctions in the vehicle or its onboard devices.

[0063] Furthermore, the driving assistance method and device of this embodiment can accelerate a vehicle at a first acceleration when accelerating it towards a set speed on a curved road, either based on curve information obtained from images captured by a camera mounted on the vehicle or based on curve information obtained from a navigation device mounted on the vehicle. Thus, even when the curved road cannot be fully captured by a camera, curve information can be obtained based on information from the navigation device, enabling appropriate acceleration of the vehicle. Furthermore, even when curve information cannot be obtained based on information from the navigation device, appropriate acceleration of the vehicle can still be achieved when curve information can be calculated by capturing images of the curved road with a camera.

[0064] Furthermore, the driving assistance method and device of this embodiment can determine whether curve information has been obtained when the vehicle decelerates to a speed below the speed limit. If curve information is not obtained, the vehicle deceleration stops, and acceleration towards the set speed begins. Thus, even without navigating a curve, acceleration towards the set speed can return the vehicle to a state of traveling at the set speed. This also improves the convenience of driving for the user.

[0065] Furthermore, the driving assistance method and device of this embodiment can also determine whether there is a user's acceleration instruction when accelerating a vehicle traveling on a curved road to a set speed, even if curve information is not obtained. If there is an acceleration instruction, the vehicle is accelerated based on the instruction. When the vehicle is accelerated based on the user's instruction, the user can cope with the increase in centrifugal force caused by the vehicle traveling on a curved road. Therefore, the user's discomfort can be reduced, and the user's intention can be reflected in the driving of the vehicle.

[0066] Furthermore, the driving assistance method and device of this embodiment can determine whether there is an acceleration instruction from the user, other than an operation that increases the set speed, when controlling a vehicle traveling on a curved road. If an acceleration instruction is received, the vehicle is accelerated based on the instruction. This reduces user discomfort and reflects the user's intention in the vehicle's driving. Moreover, even if an operation that increases the set speed is mistakenly performed while the vehicle is traveling on a curved road, the vehicle is not accelerated based on that operation, thus reducing the possibility of unintentional acceleration by the user.

[0067] The functions described in the above embodiments can be implemented by one or more processing circuits. The processing circuits include a programmed processor, circuits, and devices such as application-specific integrated circuits (ASICs), as well as circuit components configured to perform the described functions.

[0068] The present invention has been described above according to the embodiments, but the present invention is not limited to these descriptions. It is obvious to those skilled in the art that various modifications and improvements can be made. The descriptions and drawings that constitute a part of this disclosure should not be construed as limiting the present invention. Based on this disclosure, those skilled in the art will be able to recognize various alternative embodiments, examples, and techniques.

[0069] This invention naturally includes various embodiments not described herein. Therefore, the technical scope of this invention is determined solely by the specific inventive matters covered by the scope of the appropriate claims, based on the foregoing description.

[0070] Symbol Explanation

[0071] 1: Driving assistance devices

[0072] 10: Camera

[0073] 11: Radar

[0074] 12: Sonar

[0075] 13: Vehicle speed sensor

[0076] 14: GPS receiver

[0077] 15: Switch

[0078] 20: Controller

[0079] 21: Road Shape Acquisition Department

[0080] 22: Curve Information Acquisition Department

[0081] 23: Judgment Department

[0082] 24: Acceleration Setting Department

[0083] 25: Driving Control Unit

[0084] 30: Steering gear actuator

[0085] 31: Accelerator pedal actuator

[0086] 32: Brake actuator

Claims

1. A driving assistance method comprising a controller that controls a vehicle to travel at a set speed after traveling along a curved road, characterized in that, When the controller accelerates a vehicle traveling on the curved road at a speed below the speed limit based on the curved road to the set speed, Determine whether curve information related to the curve has been obtained. Having obtained the curve information, the vehicle accelerates with a first acceleration. If the curve information is not obtained, the vehicle accelerates with a second acceleration that is less than the first acceleration. When the controller decelerates the vehicle to a speed below the speed limit, Determine whether the curve information has been obtained. If the curve information is not obtained, the vehicle is brought to a stop and begins to accelerate toward the set speed.

2. The driving assistance method as described in claim 1, characterized in that, When the controller causes the vehicle traveling on the curved road to accelerate towards the set speed... If the curve information can be obtained based on images captured by a camera mounted on the vehicle, or if the curve information can be obtained based on a navigation device mounted on the vehicle, the vehicle is accelerated at the first acceleration.

3. The driving assistance method as described in claim 1, characterized in that, When the controller accelerates the vehicle traveling on the curved road towards the set speed, if it fails to obtain the curve information, the controller may fail to do so. Determine whether there is an acceleration instruction from the user of the vehicle. When the acceleration instruction is available, the vehicle is accelerated based on the acceleration instruction.

4. The driving assistance method as described in any one of claims 1 to 3, characterized in that, When the controller controls the vehicle traveling on the curved road Determine whether, in addition to operations that increase the set speed, there are any acceleration instructions from the vehicle's user. When the acceleration instruction is available, the vehicle is accelerated based on the acceleration instruction.

5. A driving assistance device for controlling a vehicle to maintain a set speed after traveling along a curved road, characterized in that, have: The curve information acquisition unit acquires curve information related to the curve road; The determination unit determines whether it has obtained curve information related to the curve road. The acceleration setting unit stops the deceleration of the vehicle when it decelerates the vehicle to a speed below the speed limit of the curve road and fails to obtain the curve information before completing the passage of the curve road, and sets the acceleration to start accelerating toward the set speed. The driving control unit causes the vehicle to accelerate at the acceleration set by the acceleration setting unit. When the driving control unit decelerates the vehicle to a speed below the speed limit, If the curve information is not obtained, the vehicle is brought to a stop and begins to accelerate toward the set speed.

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