JP7632242B2 - Driving Support Devices - Google Patents

Description

The present invention relates to a driving assistance device that prevents a vehicle from departing from the lane (roadway) on which it is traveling (departure unintentional by the driver).

Conventionally, there is known a driving assistance device (hereinafter referred to as "conventional device") capable of executing lane departure suppression control that suppresses a vehicle traveling along a lane from deviating from the lane (see, for example, Patent Document 1 below). When the vehicle deviates from the center to the end (right end or left end) in the width direction of the lane, the conventional device plays a predetermined warning sound as lane departure suppression control and controls the steering device so that the vehicle returns to the center in the width direction of the lane. When the deviation (offset value) from the center to the end in the width direction of the lane exceeds a predetermined offset threshold, the conventional device does not execute the lane departure suppression control. The conventional device sets a value to be assigned to the offset threshold according to the steering wheel operation torque (steering torque) by the driver. Specifically, when the steering torque is equal to or less than a predetermined torque threshold, the conventional device assigns a first offset value as the offset threshold. On the other hand, when the steering torque exceeds the predetermined torque threshold, the conventional device assigns a second offset value smaller than the first offset value to the offset threshold. That is, when the steering torque is relatively small, the conventional device executes (continues) lane departure prevention control until the host vehicle deviates significantly from the center in the width direction of the lane, and stops lane departure prevention control when the host vehicle starts to deviate further from the lane. On the other hand, when the steering torque is relatively large, the conventional device stops lane departure prevention control when the host vehicle deviates slightly from the center in the width direction of the lane.

JP 2011-168194 A

However, for example, there are cases where the driver moves the vehicle from the inner lane of a curved road to the outer lane (i.e., the driver intentionally changes lanes). In this case, the driver does not need to operate the steering wheel very much to move the vehicle toward the outer lane. In other words, in this case, the steering torque is relatively small. For this reason, the conventional device assigns the first offset value to the offset threshold. Therefore, lane departure suppression control continues until the vehicle deviates significantly from the center in the width direction of the inner lane to the outer lane to a certain extent, which is annoying to the driver. In this way, the practicality of the conventional device is low.

One of the objectives of the present invention is to provide a driving assistance device that can prevent the vehicle from departing from its lane and has improved practicality.

In order to solve the above problems, a driving assistance device (1) of the present invention comprises:
an on-board sensor (20) that acquires and outputs information relating to the position of the vehicle, information relating to targets located around the vehicle, and information relating to the operation of an operator of the vehicle;
a control device (10) having a lane departure prevention function for preventing the host vehicle from departing from the lane when the host vehicle deviates toward an end in a width direction of the lane, and configured to disable the lane departure prevention function when an accelerator pedal depression depth (AD) of the host vehicle exceeds a predetermined first threshold value (AD1);
Equipped with.
The control device includes:
The lane departure prevention function is configured to be disabled when the vehicle is traveling on a curved road, the vehicle is biased toward the outer periphery (OA) of the curved road, and the depression depth of the accelerator pedal exceeds a second threshold value (AD2) that is smaller than the first threshold value.

The control device of the driving assistance device according to the present invention configured as described above executes lane departure suppression control when the vehicle is biased toward the edge of the lane on which the vehicle is traveling. However, in principle, when the depression depth of the accelerator pedal exceeds a first threshold, the control device does not execute lane departure suppression control. Furthermore, when the vehicle is traveling on a curved road and is biased toward the outer periphery of the lane (when traveling in the outer periphery area), and the depression depth of the accelerator pedal exceeds a second threshold that is smaller than the first threshold, the control device does not execute lane departure suppression control. That is, when the driver accelerates the vehicle on a curved road and tries to change the driving path from the lane on the inner periphery of the curved road to the lane on the outer periphery, the lane departure suppression control is not executed at a stage where the depression depth of the accelerator pedal is relatively small. Therefore, according to the driving assistance device according to the present invention, the inconvenience to the driver can be reduced compared to the conventional device. In this way, the practicality of the driving assistance device according to the present embodiment is higher than that of the conventional device.

FIG. 1 is a block diagram of a driving assistance device according to an embodiment of the present invention. FIG. 2 is a plan view showing a scene in which a vehicle deviates from a lane. FIG. 3 is a graph showing an example of a change in the accelerator pedal depression depth threshold. FIG. 4 is a flowchart of the lane departure prevention program.

(Outline of configuration)
1, a driving assistance device 1 according to an embodiment of the present invention is mounted on a vehicle V (hereinafter, may be referred to as "host vehicle"). As will be described in detail later, the driving assistance device 1 has a lane departure prevention function that prevents the vehicle V from departing from the lane (traveling path) on the basis of information acquired from a sensor mounted on the vehicle V.

(Specific Configuration)
As shown in FIG. 1 , the driving assistance device 1 includes a driving assistance ECU 10 , an in-vehicle sensor 20 , a drive device 30 , a braking device 40 , a shift switching device 50 , and a steering device 60 .

The driving assistance ECU 10 includes a microcomputer equipped with a CPU 10a, a ROM 10b, a RAM 10c, etc. In this specification, "ECU" means an electronic control unit, and includes a microcomputer equipped with a CPU, a ROM, a RAM, etc. The CPU realizes various functions by executing instructions stored in the ROM.

The driving assistance ECU 10 is connected to other ECUs (the engine ECU 31, brake ECU 41, SBW ECU 51, and EPS ECU 61 described below) via a CAN (Controller Area Network) so that information can be transmitted and received between them.

The on-board sensor 20 includes a sensor that acquires vehicle surrounding information including information about three-dimensional objects present around the vehicle V and information about road markings around the vehicle V. That is, for example, the on-board sensor 20 includes a sensor that acquires information about moving objects such as automobiles (other vehicles), pedestrians, and bicycles, as well as fixed objects such as white lines on the road, guardrails, and traffic lights.

Specifically, the on-board sensors 20 include a radar sensor 21, an ultrasonic sensor 22, a camera 23, and a navigation system 24.

The radar sensor 21 includes a radar transmitter/receiver and a signal processor (not shown). The radar transmitter/receiver emits millimeter wave band radio waves (hereinafter referred to as "millimeter waves") to the area around the vehicle and receives millimeter waves reflected by a three-dimensional object within the emission range (i.e., reflected waves). The signal processor acquires information indicating the distance between the vehicle V and the three-dimensional object, the relative speed between the vehicle V and the three-dimensional object, the relative position (direction) of the three-dimensional object with respect to the vehicle V, etc. based on the phase difference between the transmitted millimeter wave and the received reflected wave, the attenuation level of the reflected wave, and the time from transmitting the millimeter wave to receiving the reflected wave, and outputs the information to the driving assistance ECU 10.

The ultrasonic sensor 22 transmits ultrasonic waves in pulses to a specified area around the vehicle and receives the waves reflected by a three-dimensional object. Based on the time between transmitting the ultrasonic waves and receiving the reflected waves, the ultrasonic sensor can detect the "reflection point, which is the point on the three-dimensional object where the transmitted ultrasonic waves are reflected," and the "distance between the ultrasonic sensor and the three-dimensional object," etc.

The camera 23 includes an imaging device and an image analysis device. The imaging device is, for example, a digital camera with a built-in imaging element such as a CCD (charge coupled device) or a CIS (CMOS image sensor). The imaging device is disposed on the upper part of the front windshield glass. The imaging device captures the view in front of the vehicle at a predetermined frame rate and outputs the obtained image data to the image analysis device. The image analysis device analyzes the acquired image data and obtains information about targets located in front of the vehicle V from the images. The image analysis device recognizes, for example, the light color of a traffic light located in front of the vehicle V in the traveling direction. The image analysis device also recognizes the white lines on the road (division lines, stop lines, etc.).

The navigation system 24 receives GPS signals from multiple artificial satellites, and detects the current location PV (latitude and longitude) of the vehicle V based on the multiple received GPS signals. The navigation system 24 also stores map data representing a map. The map data includes road information representing roads and traffic light position information representing the installation positions of traffic lights. The navigation system 24 transmits vehicle position data representing the detected current location PV to the driving assistance ECU 10. Furthermore, the navigation system 24 has a function of calculating the distance between two points (distance along the road).

The on-board sensor 20 further includes a sensor that acquires information regarding the driving state (speed, acceleration) of the vehicle V and information regarding the operation mode of the controls equipped on the vehicle V.

Specifically, the on-board sensors 20 include a speed sensor 25, an acceleration sensor 26, an accelerator pedal sensor 27, a brake pedal sensor 28, a shift lever sensor 29, and a steering sensor 2a.

The speed sensor 25 includes a wheel speed sensor that generates one pulse signal (wheel pulse signal) each time the wheels of the host vehicle rotate a predetermined angle. The speed sensor 25 measures the number of pulses per unit time of the wheel pulse signal transmitted from the wheel speed sensor, calculates the rotation speed (wheel speed) of each wheel based on the measured number of pulses, and calculates the host vehicle speed Vs (actual vehicle speed) based on the wheel speed of each wheel. The speed sensor 25 is capable of transmitting data representing the vehicle speed Vs to the driving assistance ECU 10.

The acceleration sensor 26 detects the acceleration G acting on the vehicle V (for example, the acceleration acting in the width direction of the vehicle V when traveling on a curved road, the acceleration acting in the front-rear direction of the vehicle V when traveling on a straight road, etc.). The acceleration sensor 26 transmits data representing the acceleration G to the driving assistance ECU 10.

The accelerator pedal sensor 27 detects the depression depth AD of the accelerator pedal (not shown) of the vehicle V. The accelerator pedal sensor 27 transmits data representing the depression depth AD of the accelerator pedal to the driving assistance ECU 10.

The brake pedal sensor 28 detects the depression depth BD of the brake pedal (not shown) of the vehicle V. The brake pedal sensor 28 transmits data representing the depression depth BD to the driving assistance ECU 10.

The shift lever sensor 29 detects the position (shift lever position SP) of the shift lever (not shown) of the vehicle V. The shift lever sensor 29 transmits data representing the shift lever position SP to the driving assistance ECU 10.

The steering sensor 2a detects the steering angle (also called the steering angle or turning angle) θ of the steering wheel. The steering sensor 2a transmits data representing the detected steering angle θ to the driving assistance ECU 10.

The drive unit 30 generates a driving force and applies the driving force to the driving wheels (left front wheel, right front wheel, left rear wheel, and right rear wheel). The drive unit 30 includes an engine ECU 31, an engine actuator 32, an internal combustion engine 33, a transmission 34, and a driving force transmission mechanism (not shown) that transmits the driving force to the wheels. The engine ECU 31 is connected to the engine actuator 32. The engine actuator 32 includes a throttle valve actuator that changes the opening degree of the throttle valve of the internal combustion engine 33. The engine ECU 31 acquires the depression depth AD of the accelerator pedal from the driving assistance ECU 10. The driving assistance ECU 10 can appropriately correct the depression depth AD acquired from the accelerator pedal sensor 27 and transmit it to the engine ECU 31. The engine ECU 31 drives the engine actuator 32 according to the depression depth AD acquired from the driving assistance ECU 10. In this way, the torque generated by the internal combustion engine 33 is controlled. The torque generated by the internal combustion engine 33 is transmitted to the drive wheels via the transmission 34 and a drive force transmission mechanism (e.g., a drive shaft).

When the vehicle V to which the driving assistance device 1 is applied is a hybrid vehicle (HEV), the engine ECU 31 can control the driving force of the vehicle generated by either or both of an internal combustion engine and an electric motor as the vehicle driving source. When the vehicle V to which the driving assistance device 1 is applied is an electric vehicle (BEV), an electric motor ECU can be used instead of the engine ECU 31 to control the driving force of the vehicle generated by an electric motor as the vehicle driving source.

The braking device 40 applies a braking force to the wheels. The braking device 40 includes a brake ECU 41, a hydraulic circuit 42, and a brake caliper 43. The hydraulic circuit 42 includes a reservoir, an oil pump, various valve devices, a hydraulic sensor, and the like (not shown). The brake caliper 43 is a hydraulic actuator equipped with a cylinder and a piston. When oil is supplied to the cylinder, the piston is pushed out of the cylinder. A brake pad is provided at the tip of the piston, and this brake pad is pressed against the brake disc. The brake ECU 41 acquires the depression depth BD of the brake pedal from the driving assistance ECU 10. The driving assistance ECU 10 can appropriately correct the depression depth BD acquired from the brake pedal sensor 28 and transmit it to the brake ECU 41. The brake ECU 41 transmits a hydraulic control command to the hydraulic circuit 42 according to the depression depth BD acquired from the driving assistance ECU 10. The hydraulic circuit 42 adjusts the hydraulic pressure in the cylinder of the brake caliper 43 in response to a hydraulic control command obtained from the brake ECU 41. In this way, the braking force of the wheel (brake disc) by the brake caliper 43 is controlled.

The shift switching device 50 switches the shift position of the transmission 34. The shift switching device 50 includes an SBW (Shift-by-Wire) ECU 51, an SBW actuator 52, a shift switching mechanism 53, and the like. The SBW ECU 51 is connected to the SBW actuator 52. The SBW ECU 51 acquires the shift lever position SP from the driving assistance ECU 10. The driving assistance ECU 10 can appropriately correct the shift lever position SP acquired from the shift lever sensor 29 and send it to the SBW ECU 51. The SBW ECU 51 transmits a shift switching command to the SBW actuator 52 according to the shift lever position SP acquired from the driving assistance ECU 10. The SBW actuator 52 controls the shift switching mechanism 53 according to the shift switching command acquired from the SBW ECU 51. In this manner, the shift position of the transmission 34 is switched.

The steering device 60 controls the steering angle of the steered wheels (left front wheel and right front wheel). The steering device 60 includes an electric power steering ECU (hereinafter referred to as "EPS ECU") 61, an assist motor 62, and a steering mechanism 63. The EPS ECU 61 is connected to the assist motor 62 (drive circuit of the assist motor 62). The assist motor 62 is incorporated into the steering mechanism 63. The steering mechanism 63 is a mechanism for steering the steered wheels. The steering mechanism 63 includes a steering wheel SW, a steering shaft US, and a steering gear mechanism (not shown). The EPS ECU 61 detects the steering torque input by the driver to the steering wheel SW using a steering torque sensor (not shown) provided on the steering shaft US, and drives the assist motor 62 based on this steering torque. The EPS ECU 61 applies a steering torque (steering assist torque) to the steering mechanism 63 by driving the assist motor 62, thereby assisting the driver's steering operation.

In addition, the EPS ECU 61 obtains the steering angle θ from the driving assistance ECU 10. The driving assistance ECU 10 can appropriately correct the steering angle θ obtained from the steering sensor 2a and transmit it to the EPS ECU 61. The EPS ECU 61 can transmit a steering command to the EPS ECU 61 according to the steering angle θ obtained from the driving assistance ECU 10. When the EPS ECU 61 receives a steering command from the driving assistance ECU 10, it drives the assist motor 62 based on the steering command. The steering torque generated by the assist motor 62 in this case is different from the steering assist torque that is applied to assist the driver's steering as described above, and is a torque that is applied to the steering mechanism 63 by the steering command from the EPS ECU 61 without the driver's steering. In this way, the steering angle of the steered wheels of the vehicle (i.e., the steering angle) is controlled.

(Lane departure prevention function)
Next, the lane departure prevention function of the driving assistance device 1 will be described. The driving assistance ECU 10 calculates a target driving line Ld based on data acquired from the radar sensor 21, the ultrasonic sensor 22, and the camera 23. The target driving line Ld is a line that extends approximately parallel to the white line RL (or a curb, a divider, etc.) on the right side of the lane on which the vehicle V is traveling and the white line LL (or a curb, a divider, etc.) at the center position between the white line RL and the white line LL (see FIG. 2). Next, the driving assistance ECU 10 calculates the deviation between the front end center position CL of the vehicle and the target driving line Ld (deviation to the right or left in the width direction of the lane (hereinafter referred to as the "offset value OFS").

In principle, when the offset value OFS (absolute value) is within a predetermined range OFSR, the driving assistance ECU 10 issues a predetermined warning to the driver. Specifically, the driving assistance ECU 10 causes the video display device of the navigation system 24 to display a predetermined image, and causes the audio device of the navigation system 24 to play a predetermined warning sound. In this way, the driving assistance device 1 notifies the driver that the vehicle is biased toward the edge of the lane in the width direction (transverse direction) and prompts the driver to correct the steering angle θ, thereby preventing the vehicle from deviating from the lane in which it is currently traveling.

However, if the accelerator pedal depression depth AD exceeds a predetermined threshold value ADth, the driving assistance ECU 10 will not issue the above warning even if the offset value OFS is within the predetermined range OFSR.

Here, the driving assistance ECU 10 generally assigns the first depression depth AD1 to the threshold value ADth. As an exception to this, when the vehicle is traveling on a curved road and is biased toward the outer periphery (when the vehicle is traveling in the dotted area in FIG. 2 (hereinafter referred to as the "outer periphery area OA")), the driving assistance ECU 10 assigns the second depression depth AD2, which is smaller than the first depression depth AD1, to the threshold value ADth (see FIG. 3).

Specifically, the driving assistance ECU 10 determines the value to be assigned to the threshold value ADth as follows. The driving assistance ECU 10 sequentially calculates the radius of curvature R of the lane in which the vehicle is traveling based on information acquired from the radar sensor 21, the ultrasonic sensor 22, the camera 23, and the navigation system 24. Furthermore, when the radius of curvature R of the lane is equal to or less than a predetermined threshold value Rth, the driving assistance ECU 10 determines whether the front end center position CL of the vehicle is biased toward the outer periphery of the lane (curved road) with respect to the target driving line Ld. When the front end center position CL of the vehicle is biased toward the outer periphery of the lane (curved road) with respect to the target driving line Ld, the driving assistance ECU 10 assigns the second depression depth AD2 to the threshold value ADth.

Next, referring to FIG. 4, the operation of the CPU 10a (hereinafter simply referred to as the "CPU") of the driving assistance ECU 10 (the lane departure prevention program that realizes the above-mentioned lane departure prevention control) will be specifically described. While the engine of the vehicle is operating (when the ignition switch is in the ON state), the CPU repeatedly executes the program at predetermined time intervals.

The CPU starts lane departure prevention processing from step 100 and proceeds to step 101.

Next, in step 101, the CPU calculates (obtains) the radius of curvature R of the lane in which the vehicle is traveling based on the information obtained from the on-board sensor 20. Then, the CPU proceeds to step 102.

When the CPU proceeds to step 102, it determines whether the radius of curvature R is equal to or less than a predetermined threshold value Rth. That is, the CPU determines whether the lane on which the host vehicle is traveling is a curved road. If the radius of curvature R is equal to or less than the threshold value Rth (if the host vehicle is traveling on a curved road (102: Yes)), the CPU proceeds to step 103. On the other hand, if the radius of curvature R exceeds the threshold value Rth (if the host vehicle is traveling on a straight road (102: No)), the CPU proceeds to step 105, which will be described later.

When the CPU proceeds to step 103, it determines whether the host vehicle is biased toward the outer periphery of the lane based on the data acquired from the on-board sensor 20. If the host vehicle is biased toward the outer periphery of the lane (if the front end center position CL is located within the outer periphery area OA (103: Yes)), the CPU proceeds to step 104. On the other hand, if the host vehicle is located in the center of the lane or biased toward the inner periphery of the lane (if the front end center position CL is located on the target driving line Ld or is located on the inner periphery of the lane (103: No)), the CPU proceeds to step 105.

If the CPU proceeds to step 105, it assigns the first depression depth AD1 to the threshold value ADth, and if the CPU proceeds to step 104, it assigns the second depression depth AD2 to the threshold value ADth. The CPU then proceeds from step 104 or step 105 to step 106.

When the CPU proceeds to step 106, it calculates (obtains) the offset value OFS based on the data obtained from the on-board sensor 20. The CPU then proceeds to step 107.

When the CPU proceeds to step 107, it determines whether the offset value OFS (the magnitude of the offset value OFS) is inside a predetermined range OFSR. If the offset value OFS is within the predetermined range OFSR (including the boundary) (107: Yes), the CPU proceeds to step 108. On the other hand, if the offset value OFS is outside the predetermined range OFSR (107: No), the CPU proceeds to step 111 and ends the lane departure prevention procedure. That is, in this case, the CPU does not issue an alarm.

When the CPU proceeds to step 108, it acquires the accelerator pedal depression depth AD from the accelerator pedal sensor 27. The CPU then proceeds to step 109.

When the CPU proceeds to step 109, it determines whether the depression depth AD (current value) exceeds the threshold value ADth. If the depression depth AD exceeds the threshold value ADth (109; Yes), the CPU proceeds to step 111 and ends the lane departure prevention process. That is, in this case, the CPU does not issue an alarm. On the other hand, if the depression depth AD is equal to or less than the threshold value ADth (109: No), the CPU proceeds to step 110.

When the CPU proceeds to step 110, it causes the video display device of the navigation system 24 to display a predetermined image and causes the audio device of the navigation system 24 to play a predetermined warning sound. The CPU then proceeds to step 111, where it ends the lane departure prevention process.

(effect)
As described above, according to the conventional device, when the driver accelerates the vehicle on a curved road and tries to change the driving path from the inner lane of the curved road to the outer lane, the lane departure suppression control, which is essentially unnecessary, continues, which may be annoying to the driver. On the other hand, the driving support ECU 10 of the driving support device 1 according to the present embodiment executes the lane departure suppression control (alarm) when the offset value OFS is within a predetermined range OFSR. However, when the depression depth AD of the accelerator pedal exceeds the threshold value ADth, the driving support ECU 10 does not execute the lane departure suppression control. Here, the driving support ECU 10 assigns the first depression depth AD1 to the threshold value ADth in principle. However, when the vehicle is traveling on a curved road and is biased toward the outer side of the lane (when traveling in the outer periphery area OA), the driving support ECU 10 assigns the second depression depth AD2, which is smaller than the first depression depth AD1, to the threshold value ADth. That is, when the driver accelerates the vehicle on a curved road and attempts to change the driving lane from the inner lane to the outer lane of the curved road, the lane departure suppression control (alarm) is stopped at a stage where the depression depth AD of the accelerator pedal is relatively small. Therefore, compared to the conventional device, the inconvenience to the driver can be reduced. Thus, the practicality of the driving support device 1 according to the present embodiment is higher than that of the conventional device.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention, as described below.

<Modification>
For example, in the above embodiment, the driving assist ECU 10 issues a warning as lane departure suppression control, but instead of or in addition to this, the driving assist ECU 10 may control the steering device 60 (assist motor 62) so that the front end center position CL is located on the target driving line Ld. That is, the driving assist ECU 10 determines the target steering angle so that the offset value OFS becomes "0". Next, the driving assist ECU 10 transmits data (steering command) representing the target steering angle to the EPS ECU 61. The EPS ECU 61 drives the assist motor 62 so that the actual steering angle of the vehicle V coincides with the target steering angle.

1...driving assistance device, 10...driving assistance ECU, 20...vehicle sensor, 30...driving device, 40...braking device, 50...shift switching device, 60...steering device, AD...pressing depth, AD1...first pressing depth, AD2...second pressing depth, ADth...threshold, OA...outer peripheral area, OFS...offset value, R...curvature, Rth...threshold, θ...steering angle

Claims (1)

an on-board sensor that acquires and outputs information relating to a position of the host vehicle, information relating to targets located around the host vehicle, and information relating to operation of an operator of the host vehicle;
a control device having a lane departure prevention function that prevents the host vehicle from departing from the lane when the host vehicle deviates toward an end in a width direction of the lane, and configured to disable the lane departure prevention function when the depression depth of an accelerator pedal of the host vehicle exceeds a predetermined first threshold value;
Equipped with
The control device includes:
The lane departure prevention function is disabled when the host vehicle is traveling on a curved road, the host vehicle is deviating toward the outer periphery of the curved road, and the depression depth of the accelerator pedal exceeds a second threshold value that is smaller than the first threshold value.
Driving assistance device.

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