Driving control device

Abstract

Provided is a driving control device capable of informing a driver in a tactile manner that the driver's operation of the steering wheel may cause a hazardous event when switching from automated driving to manual driving. A driving control device 17 switches between manual driving, which allows the steering angle of a vehicle 1 to be changeable in accordance with a driver's operation of a steering wheel 4, and automated driving. In the automated driving, a target steering angle is computed on the basis of the traveling state of the vehicle 1 and environment information, and control is performed to maintain the steering angle of the vehicle 1 at the target steering angle. Upon detecting the driver's operation on one side of the steering wheel 4 during the automated driving, the driving control device 17 switches the automated driving to the manual driving, and applies a resistance torque to the driver's operation on the one side of the steering wheel 4.

Description

Operation control device

[0001] The present invention relates to a driving control device that switches between manual driving and automatic driving of a vehicle.

[0002] Patent Document 1 discloses a driving control device that switches between manual driving of a vehicle (specifically, driving in which the steering angle of the vehicle is varied in response to the operation of the steering wheels by the driver) and automatic driving. In automatic driving, the driving control device of Patent Document 1 calculates a target steering angle based on the vehicle's running state (specifically, the vehicle's position, speed, and attitude) and vehicle environmental information (specifically, road characteristics), and controls the output of a steering motor so that the steering angle of the vehicle becomes the target steering angle.

[0003] The driving control device of Patent Document 1 switches from automatic driving to manual driving when it detects driver brake pedal operation while the vehicle is turning during automatic driving. If the steering motor output were to be instantly lost at this time, the self-aligning torque (straight-line restoring torque) would cause the vehicle's steering angle to move away from the target steering angle during automatic driving. Therefore, if the driver's steering wheel operation (specifically, steering wheel operation that changes the vehicle's steering angle in a direction approaching the target steering angle during automatic driving) is delayed after switching to manual driving, it would affect the vehicle's behavior, causing the driver to feel uncomfortable.

[0004] Therefore, when switching from automatic driving to manual driving as described above, the driving control device of Patent Document 1 calculates the output of the steering motor to cancel out the self-aligning torque, calculates the output of the steering motor to assist the driver in steering the wheels, and controls the steering motor to achieve the combined output, thereby reducing the discomfort felt by the driver.

[0005] Japanese Patent Application Laid-Open No. 2019-119298

[0006] Patent Literature 1 assumes a case where the vehicle switches from automatic driving to manual driving when the driver's brake pedal operation is detected while the vehicle is turning during automatic driving. Therefore, it assumes a case where the driver operates the steering wheel (more specifically, operates the steering wheel to change the steering angle of the vehicle in a direction approaching the target steering angle during automatic driving) after switching to manual driving.

[0007] On the other hand, the present invention assumes a case where, during automatic driving of a vehicle, when a steering wheel operation by the driver (more specifically, an operation of the steering wheel that changes the steering angle of the vehicle in a direction away from the target steering angle for automatic driving) is detected, automatic driving is switched to manual driving. In this case, depending on the driving environment of the vehicle, a dangerous event may occur due to the steering wheel operation by the driver. Therefore, it is desirable to notify the driver of this.

[0008] The present invention has been made in consideration of the above circumstances, and its purpose is to provide a driving control device that can convey to the driver via a tactile sensation that a dangerous event may occur due to the driver's operation of the steering wheel when switching from automatic driving to manual driving.

[0009] In order to achieve the above-mentioned object, the present invention provides a driving control device that switches between automatic driving and manual driving, in which the steering angle of the vehicle is varied in accordance with the operation of the steering wheel by the driver, and in the automatic driving, calculates a target steering angle based on the driving state and environmental information of the vehicle, and controls the steering angle of the vehicle to become the target steering angle.When operation of one side of the steering wheel by the driver is detected during the automatic driving, the device switches from automatic driving to manual driving and applies a resistance torque to the operation of one side of the steering wheel by the driver.

[0010] According to the present invention, when switching from automatic driving to manual driving, it is possible to convey to the driver through a tactile sensation that a dangerous event may occur due to the driver's operation of the steering wheel.

[0011] 6 is a schematic diagram showing the configuration of a vehicle according to one embodiment of the present invention. FIG. 7 is a schematic diagram showing a specific example of a vehicle driving environment when switching from automatic driving to manual driving of the vehicle according to one embodiment of the present invention. FIG. 8 is a block diagram showing the functional configuration of a driving control device according to one embodiment of the present invention. FIG. 9 is a diagram showing an equation for calculating importance according to one embodiment of the present invention. FIG. 10 is a flowchart showing the processing procedure of a driving control device according to one embodiment of the present invention. FIG. 11 is a time chart showing changes over time in the steering angle of the vehicle, the steering assist torque before correction, the importance, the resistance torque, the steering assist torque after correction, and the steering burden torque, as an example of operation according to one embodiment of the present invention. FIG. 12 is a time chart showing changes over time in parameters for calculating the importance, along with changes over time in the importance shown in FIG. 6. FIG. 13 is a time chart showing changes over time in the steering angle of the vehicle, the steering assist torque before correction, the importance, the resistance torque, the steering assist torque after correction, and the steering burden torque, as another example of operation according to one embodiment of the present invention.

[0012] An embodiment of the present invention will be described with reference to the drawings.

[0013] FIG. 1 is a schematic diagram showing the configuration of a vehicle according to an embodiment of the present invention.

[0014] The vehicle 1 is equipped with two front wheels 2, two rear wheels 3, a steering device 5 that changes the direction of the front wheels 2 in response to the driver's operation of the steering wheel 4, a drive device (not shown) that transmits the output of an engine (not shown) to, for example, the front wheels 2, an engine control device (not shown) that controls the output of the engine in response to the driver's operation of an accelerator pedal (not shown), and a brake device (not shown) that brakes the front wheels 2 and rear wheels 3 in response to the driver's operation of a brake pedal (not shown).

[0015] The steering device 5 includes a steering shaft 6 connected to the steering wheels 4 and a steering mechanism (not shown, but composed of gears, links, etc.) that changes the direction of the front wheels 2 according to the rotation angle of the steering shaft 6.

[0016] When the vehicle 1 is manually driven, the driver operates the steering wheels 4 to change the direction of the front wheels 2 and thereby change the traveling direction of the vehicle 1. The driver also operates the accelerator pedal to change the engine output and thereby change the speed of the vehicle 1. The driver also operates the brake pedal to activate the braking device and brake the vehicle 1.

[0017] The vehicle 1 is equipped with devices for detecting the driving state of the vehicle 1, including a steering angle sensor 7 for detecting the rotation angle (steering angle) of the steering shaft 6 of the steering device 5, a steering torque sensor 8 for detecting the rotation torque (steering torque) of the steering shaft 6 of the steering device 5, a yaw rate sensor 9 for detecting the yaw rate of the vehicle 1, and four wheel speed sensors 10 for detecting the rotation speed (wheel speed) of the front wheels 2 and rear wheels 3.

[0018] The vehicle 1 includes, for example, one camera 11 and multiple radars 12 (specifically, millimeter-wave radars, laser radars, etc.) as devices for acquiring information about targets present around the vehicle 1, which is environmental information about the vehicle 1. The camera 11 is disposed on the front side of the vehicle 1 and captures images of targets to identify their types. Types of targets include automobiles, motorcycles, pedestrians, etc., which are classified as moving objects, and lane markings, traffic lights, traffic signs, obstacles, etc., which are classified as stationary objects. The radars 12 are disposed at the four corners of the vehicle 1 and measure the position and speed of targets using electromagnetic waves.

[0019] The vehicle 1 may be provided with a plurality of cameras 11, which may be monocular cameras or stereo cameras. The vehicle 1 may also be provided with a plurality of ultrasonic sensors or a plurality of LiDARs (Light Detection and Ranging) instead of the plurality of radars 12.

[0020] The vehicle 1 includes a communication device 13 that acquires environmental information about the vehicle 1 via wireless communication. The communication device 13 receives information, including the type, location, and speed of a target object, from, for example, another vehicle or a mobile phone owned by a pedestrian. The communication device 13 receives information, including the type and location of a target object, and signal information (specifically, the current signal color and the time until the signal color changes to another signal color), from, for example, a traffic light. The communication device 13 receives speed regulation information (specifically, speed regulation and its section, etc.), lane regulation information (specifically, restricted lanes and their sections, etc.), congestion information (specifically, congested sections, etc.), road construction information (specifically, construction sections and restriction details, etc.), accident information (specifically, accident sections and restriction details, etc.), weather information (specifically, weather details and its sections, etc.), and road surface information (specifically, road surface conditions and its sections, etc.) from, for example, a data center (in other words, a facility that accumulates multiple pieces of information and transmits necessary information).

[0021] The vehicle 1 includes a biometric information sensor 14 that detects the biometric information of the driver, and a meter 15 and a buzzer 16 that provide information to the driver. The biometric information sensor 14 processes an image of the driver taken with a camera, for example, to detect the driver's line of sight.

[0022] The vehicle 1 is equipped with a driving control device 17, a steering control device 18, and a speed control device 19. The driving control device 17 has a processor that stores a program and a processor that performs processing in accordance with the program, and switches between manual driving and automatic driving of the vehicle 1. In the automatic driving of the vehicle 1, the driving control device 17 calculates a target course and target speed of the vehicle 1 based on the running state of the vehicle 1 acquired using the steering angle sensor 7, steering torque sensor 8, yaw rate sensor 9, and wheel speed sensor 10, and environmental information of the vehicle 1 acquired using the camera 11, radar 12, and communication device 13.

[0023] The driving control device 17 calculates a target steering angle for following the target course of the vehicle 1, calculates a rotational torque (hereinafter referred to as steering assist torque) to be applied to the steering shaft 6 of the steering device 5 in accordance with this target steering angle, and outputs a command including this steering assist torque to the steering control device 18. The steering control device 18 includes a steering motor (not shown) that applies the steering assist torque to the steering shaft 6 of the steering device 5, and a control circuit (not shown) that controls the steering motor in accordance with a command from the driving control device 17. The steering motor is controlled in accordance with the command from the driving control device 17, and the steering angle of the vehicle 1 is controlled to become the target steering angle.

[0024] The driving control device 17 outputs a command including a target speed of the vehicle 1 to the speed control device 19. The speed control device 19 has a processor that stores a program and a processor that performs processing according to the program, and controls the engine and the brake device in response to the command from the driving control device 17. In this way, the speed of the vehicle 1 is controlled to become the target speed.

[0025] One of the features of this embodiment is that the driving control device 17 switches from automatic driving to manual driving when it detects the driver's operation of one side of the steering wheel 4 (more specifically, the operation of the steering wheel 4 that changes the steering angle of the vehicle 1 in a direction away from the target steering angle for automatic driving) during automatic driving of the vehicle 1. However, depending on the driving environment of the vehicle 1, a dangerous event may occur due to the driver's operation of the steering wheel 4. As a specific example, a case will be described in which the vehicle 1 is traveling in lane 100A on a road where lanes 100A and 100B on one side narrow to lane 100A, as shown in FIG.

[0026] During autonomous driving of the vehicle 1, the driving control device 17 calculates a target path 102 for the vehicle 1 to travel within the lane 100A based on lane regulation information indicating that one lane 100A, 100B, is narrowed to lane 100A, the positions of the dividing lines 101A, 101B that make up lane 100A, and the driving state of the vehicle 1. When the driving control device 17 detects that the driver has turned the steering wheel 4 to the right, it switches from autonomous driving to manual driving. As a result, the vehicle 1 travels along a path 103 that differs from the autonomous driving target path 102. This may result in the occurrence of a dangerous event.

[0027] Therefore, when the driving control device 17 of this embodiment detects the driver's operation of one side of the steering wheel 4 during automatic driving of the vehicle 1, it switches from automatic driving to manual driving and applies a resistance torque (in other words, a torque in the opposite direction to the direction of operation of the steering wheel 4) to the driver's operation of one side of the steering wheel 4. In this way, when switching from automatic driving to manual driving, it is possible to convey to the driver through a tactile sensation that a dangerous event may occur due to the driver's operation of the steering wheel 4.

[0028] The functional configuration of the driving control device 17 of this embodiment will be described with reference to Fig. 3. Fig. 3 is a block diagram showing the functional configuration of the driving control device 17 of this embodiment. Note that Fig. 3 shows the functional configuration of the driving control device 17 related to steering control of the vehicle 1, and omits the functional configuration related to speed control of the vehicle 1. Hereinafter, description of the speed control of the vehicle 1 will be omitted.

[0029] The driving control device 17 has, as functional components, a driving state acquisition unit 20, an environmental information acquisition unit 21, an automatic driving control unit 22, a manual driving control unit 23, and a driving switching unit 24. The automatic driving control unit 22 has a target steering angle calculation unit 25 and a steering assist torque calculation unit 26. The manual driving control unit 23 has a steering assist torque calculation unit 27, an importance calculation unit 28, and a resistance torque calculation unit 29.

[0030] The traveling state acquisition unit 20 acquires the traveling state of the vehicle 1 using the steering angle sensor 7, the steering torque sensor 8, the yaw rate sensor 9, and the wheel speed sensor 10. In particular, it acquires the steering angle of the vehicle 1 detected by the steering angle sensor 7 and the steering torque of the vehicle 1 detected by the steering torque sensor 8. It also acquires the yaw rate of the vehicle 1 detected by the yaw rate sensor 9, and calculates the turning radius of the vehicle 1 based on the yaw rate of the vehicle 1 and the steering angle of the vehicle 1 detected by the steering angle sensor 7. It also calculates the speed and acceleration of the vehicle 1 based on the rotational speeds of the front wheels 2 and the rear wheels 3 detected by the turning half wheel speed sensor 10 of the vehicle 1.

[0031] The environmental information acquisition unit 21 acquires environmental information about the vehicle 1 using the camera 11, the radar 12, and the communication device 13. Specifically, it processes an image of a target captured by the camera 11 to identify the type of the target. It also acquires the position and speed of the target measured by the radar 12. It also acquires information including the type, position, and speed of the target received by the communication device 13. It also acquires traffic light information, speed regulation information, lane regulation information, congestion information, road construction information, accident information, weather information, and road surface information received by the communication device 13.

[0032] The target steering angle calculation unit 25 of the automatic driving control unit 22 calculates a target course of the vehicle 1 based on the driving state of the vehicle 1 acquired by the driving state acquisition unit 20 and the environmental information of the vehicle 1 acquired by the environmental information acquisition unit 21, for example, so that the vehicle 1 will drive within a lane and avoid collision with other vehicles, etc. Then, it calculates a target steering angle for following the target course of the vehicle 1. The steering assist torque calculation unit 26 of the automatic driving control unit 22 calculates a steering assist torque for setting the steering angle of the vehicle 1 to the target steering angle.

[0033] The driving switching unit 24 detects the operation of the steering wheels 4 by the driver based on the detection results of at least one of the steering angle sensor 7 and the steering torque sensor 8 acquired by the driving state acquisition unit 20. Then, when the driving switching unit 24 does not detect the operation of the steering wheels 4 by the driver, it switches to automatic driving. That is, it outputs a command including the steering assist torque calculated by the steering assist torque calculation unit 26 of the automatic driving control unit 22 to the steering control device 18. This controls the steering angle of the vehicle 1 to become the target steering angle. On the other hand, when the driving switching unit 24 detects the operation of the steering wheels 4 by the driver, it switches to manual driving. That is, it outputs a command including the steering assist torque calculated by the steering assist torque calculation unit 27 of the manual driving control unit 23 to the steering control device 18.

[0034] The steering assist torque calculation unit 27 of the manual driving control unit 23 calculates, as the steering assist torque, a torque for improving the operability of the steered wheels 4 by the driver, for example. In detail, the steering assist torque calculation unit 27 calculates a self-aligning torque (straight-line restoring torque) based on the steering angle of the vehicle 1 acquired by the driving state acquisition unit 20, and calculates a torque that cancels out this self-aligning torque and the friction torque of the steering shaft 6 as the steering assist torque.

[0035] The importance calculation unit 28 of the manual driving control unit 23 calculates the importance (A) of adding resistance torque using, for example, the formula shown in Figure 4. In the formula, X1 is the driver's concentration on the driving of the vehicle 1, X2 is the occurrence probability of a dangerous event caused by the driving of the vehicle 1, and X3 is the degree of deviation of the driving state of the vehicle 1 from traffic rules. In the formula, α is the psychological stress on the driver caused by the driving environment of the vehicle 1, and β is the driver's level of attention to dangerous events. A method for calculating the parameters X1, X2, X3, α, and β will be described.

[0036] The importance calculation unit 28 calculates the driver's concentration level (X1) based on the driver's line of sight direction acquired using the biological information sensor 14. Specifically, the importance calculation unit 28 calculates the driver's concentration level (X1) so that the smaller the frequency or amplitude of changes in the driver's line of sight direction, the smaller the driver's concentration level (X1) is. As the driver's concentration level (X1) decreases, the importance level (A) increases.

[0037] The importance calculation unit 28 predicts the path and speed of the vehicle 1 during manual driving based on the driving state of the vehicle 1 acquired by the driving state acquisition unit 20. Then, based on the predicted path and speed of the vehicle 1 and the environmental information of the vehicle 1 acquired by the environmental information acquisition unit 21, it predicts the location and time at which a dangerous event (for example, an event in which the vehicle 1 deviates from its lane or an event in which the vehicle 1 collides with another vehicle) will occur. Then, it calculates the spatial or temporal proximity to the occurrence of the dangerous event as the probability of occurrence of the dangerous event (X2). As the probability of occurrence of the dangerous event (X2) increases, the importance (A) increases.

[0038] The importance calculation unit 28 calculates the deviation (X3) of the driving state of the vehicle 1 from the traffic rules based on the predicted course and speed of the vehicle 1 as described above, and the traffic light information, speed regulation information, and lane regulation information acquired by the environmental information acquisition unit 21. As the deviation (X3) of the driving state of the vehicle 1 increases, the importance (A) increases.

[0039] The importance calculation unit 28 calculates the psychological stress (α) of the driver based on the traffic congestion information, road construction information, accident information, weather information, and road surface information acquired by the environmental information acquisition unit 21. As the psychological stress (α) of the driver increases, the importance (A) increases.

[0040] The importance calculation unit 28 calculates the driver's attention level (β) based on the driver's line of sight acquired using the biological information sensor 14. Specifically, the importance calculation unit 28 calculates the driver's attention level (β) from the degree to which the position of the occurrence of the above-mentioned dangerous event coincides with the driver's line of sight and the amount of variation in the driver's line of sight. As the driver's attention level (β) decreases, the importance calculation unit 28 calculates the driver's attention level (β) based on the degree to which the position of the above-mentioned dangerous event coincides with the driver's line of sight and the amount of variation in the driver's line of sight. As the driver's attention level (β) decreases, the importance calculation unit 28 calculates the driver's attention level (β) based on the degree to which the driver's line of sight coincides with the position of the occurrence of the above-mentioned dangerous event ... dangerous event and the amount of variation in the driver's line of sight.

[0041] The resistance torque calculation unit 29 of the manual driving control unit 23 calculates the magnitude of the resistance torque so that it is proportional to the importance calculated by the importance calculation unit 28.

[0042] The steering assist torque calculation unit 27 of the manual driving control unit 23 determines the direction in which the driver operates the steering wheels 4 when switching from automatic driving to manual driving, based on the target steering angle calculated by the target steering angle calculation unit 25 of the automatic driving control unit 22 and the steering angle acquired by the driving state acquisition unit 20, and sets the positive or negative resistance torque according to the result of the determination. Then, a correction is made by adding the resistance torque to the steering assist torque calculated as described above.

[0043] The processing procedure of the operation control device 17 of this embodiment will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the processing procedure of the operation control device 17 of this embodiment.

[0044] In step S1, the driving control device 17 controls the automatic driving. That is, the driving switching unit 24 outputs a command including the steering assist torque calculated by the steering assist torque calculation unit 26 of the automatic driving control unit 22 to the steering control device 18.

[0045] Proceeding to step S2, the driving control device 17 determines whether or not it has detected the operation of the steering wheel 4 by the driver. If it does not detect the operation of the steering wheel 4 by the driver, it returns to step S1 and continues the control of the automatic driving. On the other hand, if it detects the operation of the steering wheel 4 by the driver, it proceeds to step S3. Note that when it detects the operation of the steering wheel 4 by the driver for the first time, it initializes flag F=0.

[0046] In step S3, the driving control device 17 determines whether or not the correction start condition is met. To explain in more detail, the importance calculation unit 28 of the manual driving control unit 23 calculates the importance, and the steering assist torque calculation unit 27 of the manual driving control unit 23 determines whether or not to start correcting the steering assist torque depending on whether the importance is equal to or greater than a threshold value.

[0047] If the correction start condition is not met in step S3 (more specifically, if the importance is less than the threshold value), the flag F is changed to 1, and the process proceeds to step S4. In step S4, the driving control device 17 controls manual driving. That is, the driving switching unit 24 outputs a command including the uncorrected steering assist torque calculated by the steering assist torque calculation unit 27 of the manual driving control unit 23 to the steering control device 18. Thereafter, if the driver continues to operate the steered wheels 4, step S4 is repeated. At this time, since flag F=1, step S3 is skipped.

[0048] When the correction start condition is met in step S3 (more specifically, when the importance is equal to or greater than the threshold), the flag F is changed to 2, and the process proceeds to step S5. In step S5, the driving control device 17 determines whether the correction end condition is met. More specifically, the steering assist torque calculation unit 27 of the manual driving control unit 23 determines whether to end the correction of the steering assist torque depending on whether a predetermined time has elapsed since switching to manual driving. Initially, the predetermined time has not elapsed, so the correction end condition is not met, and the process proceeds to step S6.

[0049] In step S6, the resistance torque calculation unit 29 of the manual driving control unit 23 calculates the magnitude of the resistance torque. Proceeding to step S7, the steering assist torque calculation unit 27 of the manual driving control unit 23 sets the positive or negative of the resistance torque and performs a correction by adding this resistance torque to the steering assist torque. Proceeding to step S4, the driving switching unit 24 outputs a command including the steering assist torque calculated and corrected by the steering assist torque calculation unit 27 of the manual driving control unit 23 to the steering control device 18. Thereafter, if the driver continues to operate the steered wheels 4, steps S5, S6, S7, and S4 are repeated. At this time, since flag F=2, step S3 is skipped but step S5 is not skipped.

[0050] Thereafter, when the correction end condition is met in step S5 (more specifically, when a predetermined time has elapsed since switching to manual driving), the flag F is changed to 1, and the process proceeds to step S4. In step S4, the driving switching unit 24 outputs a command including the uncorrected steering assist torque calculated by the steering assist torque calculation unit 27 of the manual driving control unit 23 to the steering control device 18. Thereafter, if the driver continues to operate the steered wheels 4, step S4 is repeated.

[0051] An example of the operation and effects of this embodiment will be described with reference to FIGS. 6 and 7 . FIG. 6 is a time chart showing, as an example of the operation of this embodiment, the changes over time in the steering angle of the vehicle 1, the steering assist torque before correction, the importance, the resistance torque, the steering assist torque after correction, and the steering burden torque. The steering angle of the vehicle 1 is set to zero when the vehicle 1 is traveling straight ahead, positive when the vehicle 1 is traveling to the right, and negative when the vehicle 1 is traveling to the left. The steering assist torque and the resistance torque are set to positive when the steering shaft 6 is turned clockwise, and negative when the steering shaft 6 is turned counterclockwise. FIG. 7 is a time chart showing the changes over time in the importance shown in FIG. 6 as well as the changes over time in the parameters X1, X2, α, and β used to calculate the importance. Note that FIG. 7 does not show the changes over time in the parameter X3 because the parameter X3=0.

[0052] Before time t1, the driver does not operate the steering wheels 4, and the vehicle 1 is automatically driven. The driving control device 17 calculates a target steering angle (a negative value corresponding to the left direction of the vehicle 1 in FIG. 6), calculates a corresponding steering assist torque, and outputs a command including the steering assist torque to the steering control device 18. In this way, the steering angle of the vehicle 1 is controlled to become the target steering angle.

[0053] At time t1, the driver starts to turn the steering wheels 4 to the right, and the vehicle 1 switches to manual driving. The driver's turn of the steering wheels 4 to the right causes the steering angle of the vehicle 1 to move away from the target steering angle. The driving control device 17 calculates a torque as a steering assist torque to improve the operability of the steering wheels 4 by the driver.

[0054] The driving control device 17 calculates the driver's concentration on the driving of the vehicle 1 (X1), the probability of occurrence of a dangerous event due to the driving of the vehicle 1 (X2), the deviation of the driving state of the vehicle 1 from traffic rules (X3), the psychological stress on the driver due to the driving environment of the vehicle 1 (α), and the driver's attention to the dangerous event (β), and calculates the importance based on these (see FIG. 7). Then, since the importance is equal to or greater than the threshold, correction of the steering assist torque is started.

[0055] The driving control device 17 calculates the magnitude of the resistance torque so as to be proportional to the importance. Furthermore, it determines that the direction of operation of the steering wheels 4 by the driver when switching from automatic driving to manual driving is rightward, and accordingly sets the resistance torque to a negative value. Then, it performs a correction by adding the resistance torque to the steering assist torque calculated as described above. Then, it outputs a command including the corrected steering assist torque to the steering control device 18. This adds a resistance torque to the rightward operation of the steering wheels 4 by the driver. As a result, the steering torque borne by the driver (steering burden torque) increases from the value indicated by the dotted line in the figure to the value indicated by the solid line in the figure. Therefore, it is possible to tactilely communicate to the driver that a dangerous event may occur due to the operation of the steering wheels 4 by the driver.

[0056] At time t2, a predetermined time has elapsed since switching to manual driving, and the driving control device 17 ends the correction of the steering assist torque. After time t2, the driving control device 17 outputs a command including the uncorrected steering assist torque to the steering control device 18. As a result, no resistance torque is applied to the operation of the steered wheels 4 by the driver. This improves the operability of the steered wheels 4 by the driver.

[0057] Another example of the operation and the effects of this embodiment will be described with reference to Fig. 8. Fig. 8 is a time chart showing, as another example of the operation of this embodiment, the changes over time in the steering angle of the vehicle, the steering assist torque before correction, the importance, the resistance torque, the steering assist torque after correction, and the steering burden torque.

[0058] Before time t3, the driver does not operate the steering wheel 4, and the vehicle 1 is being driven automatically. At time t3, the driver starts to turn the steering wheel 4 to the right, and the vehicle 1 is switched to manual driving. Because the importance is equal to or greater than the threshold, the driving control device 17 starts correcting the steering assist torque.

[0059] The driving control device 17 calculates the magnitude of the resistance torque so that it is proportional to the importance. It also determines that the direction of operation of the steering wheels 4 by the driver when switching from automatic driving to manual driving is rightward, and accordingly sets the resistance torque to a negative value. It then performs a correction by adding the resistance torque to the steering assist torque. It then outputs a command including the corrected steering assist torque to the steering control device 18. As a result, a resistance torque is added to the rightward operation of the steering wheels 4 by the driver, and the steering burden torque increases. Therefore, it is possible to tactilely communicate to the driver that a dangerous event may occur due to the operation of the steering wheels 4 by the driver.

[0060] At time t4, the driver switches from steering the steered wheels 4 to the right to steering the left. As the driver operates the steered wheels 4 to the left, the steering angle of the vehicle 1 approaches the target steering angle. The driving control device 17 continues to correct the steering assist torque by adding the resistance torque to the steering assist torque, while keeping the resistance torque set to a negative value. Then, it outputs a command including the corrected steering assist torque to the steering control device 18. As a result, a promotion torque (in other words, a torque on the same side as the direction of operation of the steered wheels 4) is added to the left operation of the steered wheels 4 by the driver, and the steering burden torque is reduced. Therefore, it is possible to tactilely convey to the driver that there is a possibility that a dangerous event can be avoided by operating the steered wheels 4 by the driver.

[0061] At time t5, although a predetermined time has not yet elapsed since the switch to manual driving, the driver no longer operates the steering wheel 4, and the vehicle 1 switches to automatic driving.

[0062] Although not specifically described in the above embodiment, the driving control device 17 may process an image of the driver taken by a camera, for example, to identify the driver, and may correct the driver's concentration level (X1), psychological stress (α), and attention level (β) accordingly. More specifically, the driving control device 17 may create correction functions for the driver's concentration level (X1), psychological stress (α), and attention level (β) based on data about each driver (e.g., the history of the driving state of the vehicle 1 during manual driving, or the number of dangerous events that have occurred), and use these correction functions to correct the driver's concentration level (X1), psychological stress (α), and attention level (β).

[0063] In the above embodiment, the driving control device 17 calculates the importance level based on the driver's concentration level (X1) on the driving of the vehicle 1, the probability of occurrence of a dangerous event due to the driving of the vehicle (X2), the deviation of the driving state of the vehicle from traffic rules (X3), the psychological stress (α) of the driver due to the driving environment of the vehicle, and the driver's attention level (β) to the dangerous event. However, this is not limiting. The driving control device 17 may calculate the importance level without considering the driver's psychological stress (α). The driving control device 17 may calculate the importance level without considering the driver's attention level (β). The driving control device 17 may calculate the importance level without considering at least one of the probability of occurrence of a dangerous event (X2) and the deviation of the driving state of the vehicle (X3). The driving control device 17 may calculate the importance level without considering the driver's concentration level (X1). In other words, the driving control device 17 may calculate the importance based on one or two of the driver's concentration level (X1), the probability of a dangerous event occurring (X2), and the deviation level of the vehicle's driving state (X3).

[0064] Furthermore, in the above embodiment, the biometric information sensor 14 detects the driver's line of sight, but this is not limiting. The biometric information sensor 14 may process an image of the driver captured using a camera to detect the acceleration of the driver's head. In this case, the driving control device 17 calculates the driver's concentration level (X1) based on the correlation between the head acceleration and the acceleration of the vehicle 1. The biometric information sensor 14 may also detect the driver's pulse, heart rate, or brain waves. In this case, the driving control device 17 calculates the driver's concentration level (X1) based on changes in the driver's pulse, heart rate, or brain waves. Instead of or in addition to the above-described calculation method, the driving control device 17 may calculate the driver's concentration level (X1) based on the difference between the driving state (e.g., steering angle) of the vehicle 1 during automatic driving and manual driving.

[0065] In the above embodiment, the operation control device 17 varies the magnitude of the resistance torque depending on the importance level, but this is not limiting. The operation control device 17 may vary the magnitude of the resistance torque so that it is proportional to the self-aligning torque (straight-line restoration torque), or may fix the magnitude. The operation control device 17 may vary the rate of change of the rise and fall of the resistance torque depending on the importance level.

[0066] In the above embodiment, the driving control device 17 applies a resistance torque in addition to a torque for improving the operability of the steered wheels 4 by the driver during manual driving, but this is not limiting. The driving control device 17 may apply only a resistance torque during manual driving.

[0067] 1 vehicle 4 steering wheel 17 driving control device

Claims

1. A driving control device that switches between manual driving, in which the steering angle of a vehicle is varied according to an operation of a steering wheel by a driver, and automatic driving, and in the automatic driving, calculates a target steering angle based on the driving state and environmental information of the vehicle, and controls the steering angle of the vehicle to be the target steering angle, wherein when an operation of one side of the steering wheel by the driver is detected during the automatic driving, the automatic driving is switched to the manual driving, and a resistance torque is added to the operation of one side of the steering wheel by the driver.

2. The driving control device according to claim 1, wherein an importance level for adding the resistance torque is calculated, and at least one of the magnitude of the resistance torque and the rate of change of the rise and fall of the resistance torque is varied in proportion to the importance level.

3. The driving control device according to claim 2, wherein the importance level is calculated based on at least one of the degree of concentration of the driver on the driving of the vehicle, the probability of occurrence of a dangerous event due to the driving of the vehicle, and the degree of deviation of the driving state of the vehicle from traffic rules.

4. The driving control device according to claim 3, wherein the importance level is calculated in further consideration of the mental load of the driver due to the driving environment of the vehicle.

5. The driving control device according to claim 3, wherein the importance level is calculated in further consideration of the degree of attention of the driver to the dangerous event.

6. The driving control device according to claim 1, wherein the magnitude of the resistance torque is varied in proportion to the straight-ahead restoring torque that changes according to the steering angle of the vehicle.

7. The driving control device according to claim 1, wherein the addition of the resistance torque is terminated when a predetermined time has elapsed after switching to the manual driving or when switching from the manual driving to the automatic driving.

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