Vehicle control device and vehicle control method

Abstract

This vehicle control device can be installed in a vehicle driven by a driver, and comprises a surrounding area risk determining unit that determines a risk region, which is a high-risk region existing around the vehicle, from external environment information, a model calculating unit that calculates a model driving operation amount on the basis of at least the risk region, an operation amount determining unit that determines an assist operation amount for supporting a driving operation of the driver, on the basis of a first parameter for determining the magnitude of the assist operation amount, the model driving operation amount, and the driver's driving operation amount, a support acceptance degree determining unit that, on the basis of at least one of the assist operation amount, the driving operation amount, and a driver state representing a state of the driver, calculates an acceptability quantitative value indicating the driver's degree of acceptability of the assist operation amount, an operation amount changing unit that changes the first parameter such that the lower the acceptability quantitative value, the smaller the assist operation amount, and a driving behavior determining unit that, on the basis of the driving operation amount and the risk region, calculates a safe driving degree, which is an indicator of the safety of the driver's driving operation of the vehicle, wherein the operation amount changing unit additionally changes the first parameter on the basis of the safe driving degree.

Description

Vehicle control device and vehicle control method

[0001] The present invention relates to a vehicle control device and a vehicle control method.

[0002] Patent Literature 1 discloses a configuration for controlling an actuator to assist driving in accordance with the driver's state. Patent Literature 1 discloses a driving assistance device based on driver emotion, which includes an environmental difficulty calculation means for calculating an environmental difficulty required for the driver's driving operation depending on the external environment of the vehicle, a driving skill evaluation means for evaluating the driving skill based on the driver's driving operation, a driver state estimation means for estimating the driver's state relative to the external environment from the environmental difficulty calculated by the environmental difficulty calculation means and the driving skill evaluated by the driving skill evaluation means, and a driving assistance means for providing driving assistance, wherein the driving assistance means provides driving assistance in accordance with the driver's state estimated by the driver state estimation means when the driving skill evaluated by the driving skill evaluation means is high, equal to or higher than a predetermined value, and prohibits driving assistance based on the driver's state estimated by the driver state estimation means when the driving skill is low, equal to or lower than the predetermined value.

[0003] Japanese Patent Application Publication No. 2015-110417

[0004] The invention described in Patent Document 1 does not take into consideration the acceptability of the driving assistance by the driver.

[0005] a driving behavior determination unit that calculates a safe driving level, which is an index of the safety of the driver's driving operation, based on the driving operation amount and the risk area; a norm calculation unit that calculates a standard driving operation amount based on at least the risk area; an operation amount determination unit that determines an assist operation amount based on a first parameter that determines the magnitude of an assist operation amount to assist the driver's driving operation, the standard driving operation amount, and the driver's driving operation amount; an assistance acceptance determination unit that calculates an acceptability quantitative value that indicates the driver's degree of acceptability to the assist operation amount based on at least one of the assist operation amount, the driving operation amount, and a driver state that represents the driver's state; an operation amount change unit that changes the first parameter so that the assist operation amount is smaller the lower the acceptability quantitative value; and a driving behavior determination unit that calculates a safe driving level, which is an index of the safety of the driver's driving operation of the vehicle, based on the driving operation amount and the risk area; and the operation amount change unit further changes the first parameter based on the safe driving level.a control amount determination process for calculating a standard driving operation amount based on at least the risk area; a first parameter for determining the magnitude of an assist operation amount for assisting the driver's driving operation, the standard driving operation amount, and the driver's driving operation amount; an assistance acceptance determination process for calculating an acceptability quantitative value indicating the driver's degree of acceptability to the assist operation amount based on at least one of the assist operation amount, the driving operation amount, and a driver state indicating the driver's state; an assistance acceptance change process for changing the first parameter so that the assist operation amount is smaller the lower the acceptability quantitative value; and a driving behavior determination process for calculating a safe driving level, which is an index of the safety of the driver's driving operation of the vehicle, based on the driving operation amount and the risk area;

[0006] According to the present invention, the amount of assistance can be reduced for drivers who drive a vehicle safely and who are less receptive to assistance.

[0007] FIG. 1 is a plan view showing the overall configuration of a vehicle; FIG. 2 is a functional block diagram of a vehicle control device in a first embodiment; FIG. 3 is a diagram explaining the processing of the driver state acquisition unit; FIG. 4 is a diagram explaining the processing of the surrounding risk determination unit; FIG. 5 is a diagram explaining the processing of the norm calculation unit; FIG. 6 is a diagram explaining the processing of the norm calculation unit; FIG. 7 is a diagram explaining the processing of the norm calculation unit; FIG. 8 is a diagram explaining the processing of the norm calculation unit;

[0008] -First Embodiment- A first embodiment of a vehicle control device will be described below with reference to FIGS.

[0009] FIG. 1 is a plan view showing the overall configuration of a vehicle 1 (sometimes referred to as the host vehicle 1) according to a first embodiment. The vehicle 1 includes a vehicle control device 2, an external control device 3, a combined sensor 4, wheels 11, a motor 12, a brake mechanism 13, a steering mechanism 14, a suspension 15, an accelerator pedal 16, a brake pedal 17, a steering wheel 18, and an external sensor 19. In the drawing, FL denotes the front left, FR denotes the front right, RL denotes the rear left, and RR denotes the rear right. Taking the wheel 11 as an example, 11FL, 11FR, 11RL, and 11RR denote the front left wheel, front right wheel, rear left wheel, and rear right wheel, respectively. Furthermore, F denotes the front side, and R denotes the rear side.

[0010] Below, we will define the front-to-back direction of vehicle 1 as the x-axis (forward direction is positive), the left-to-right direction as the y-axis (left direction is positive), and the up-to-down direction as the z-axis (upward direction is positive), and then explain the details of each component in turn.

[0011] The external sensor 19 is a sensor that senses the outside of the vehicle 1, such as a camera, radar, or LiDAR. Hereinafter, data acquired by the external sensor 19 will be referred to as external data. For example, fisheye cameras with a 180-degree field of view may be installed on the front, left, right, and rear surfaces of the vehicle 1 (19F, 19SL, 19SR, and 19R). By installing these external sensors 19 on the front, left, right, and rear surfaces of the vehicle 1, the relative distance and relative speed of objects around the vehicle 1, such as vehicles, bicycles, pedestrians, and obstacles, can be detected. While the present embodiment illustrates a combination of the above sensors as an example of a sensor configuration, this is not limiting and may also include a combination of ultrasonic sensors, stereo cameras, infrared cameras, laser radars, and the like. Furthermore, a laser radar capable of sensing 360 degrees around the vehicle 1 may be mounted on the ceiling of the vehicle 1. The external data may be input at least to the vehicle control device 2 and further to the external control device 3.

[0012] The vehicle control device 2 performs integrated control of each actuator in response to driver operation, external commands from the external control device 3, and detection signals from the combined sensor 4. The detection signals from the combined sensor 4 are detection signals related to control axes with a total of six degrees of freedom, including longitudinal, lateral, and vertical acceleration, and roll, pitch, and yaw rates. The actuators include a motor 12, a brake mechanism 13, a steering mechanism 14, and a suspension 15. Specifically, the vehicle control device 2 is an ECU (Electronic Control Unit) equipped with hardware such as a calculation device (CPU), a main storage device (e.g., semiconductor memory), an auxiliary storage device, and a communication device. The calculation device executes programs loaded from the auxiliary storage device to the main storage device, thereby achieving the functions described below. However, the following description will omit such well-known technologies as appropriate.

[0013] The external control device 3 is a higher-level controller for executing driving assistance control and automatic driving control via the vehicle control device 2. The external control device 3 performs calculations using external data acquired by the external sensor 19 and outputs the calculation results to the vehicle control device 2 as external commands. A first example of a calculation using external data by the external control device 3 is the calculation of a speed command value and an acceleration command value for implementing adaptive cruise control (ACC) that follows a preceding vehicle. A second example of a calculation using external data by the external control device 3 is the calculation of a yaw command value, etc., for implementing lane keep control (LKC) that keeps the vehicle within its lane. Note that although the vehicle control device 2 and the external control device 3 are separate entities in FIG. 1 , both may be implemented by a single ECU.

[0014] The drive system of the vehicle 1 will now be described. The vehicle 1 includes, as a main part of the drive system, a torque generating device that applies driving force to each of the wheels 11. An example of this torque generating device is an engine or a motor that transmits driving force to a pair of left and right wheels 11 via a differential gear and a drive shaft. Another example of a torque generating device is an in-wheel motor 12 that independently drives each of the wheels 11. Below, the present embodiment will be described in detail assuming the vehicle structure of FIG. 1 in which an in-wheel motor 12 is mounted on each of the wheels 11.

[0015] When the driver wants to move the vehicle 1 forward or backward, the driver sets the shift lever to the desired setting and then operates the accelerator pedal 16. At this time, the stroke sensor 16a detects the amount of depression of the accelerator pedal 16, and the acceleration control device 16b converts the amount of depression and outputs an accelerator command to the vehicle control device 2. The vehicle control device 2 supplies power corresponding to the input accelerator command from a battery (not shown) to the motors 12 of each wheel, and controls the torque of each motor. As a result, the vehicle 1 can be accelerated or decelerated in accordance with the operation of the accelerator pedal 16.

[0016] Furthermore, when driving assistance or automatic driving is performed in response to an external command from the external control device 3, the vehicle control device 2 controls the motor torque of each wheel by supplying the desired power to the motor 12 of each wheel in response to the input external command. As a result, the vehicle 1 is accelerated or decelerated, and the desired driving assistance or automatic driving is performed.

[0017] Next, the braking system of the vehicle 1 will be described. As a key component of the braking system, the vehicle 1 includes wheel cylinders 13a that apply braking force to each of the wheels 11. Each wheel cylinder 13a is composed of, for example, a cylinder, a piston, a pad, a disc rotor, and the like. In each wheel cylinder 13a, a piston is propelled by hydraulic fluid supplied from a master cylinder, and a pad connected to the piston is pressed against a disc rotor that rotates together with the wheel 11. The brake torque acting on the disc rotor then becomes a braking force acting between the wheel 11 and the road surface.

[0018] When the driver wishes to brake the vehicle 1, the driver operates the brake pedal 17. At this time, the force with which the driver depresses the brake pedal 17 is increased by a brake booster (not shown), and a master cylinder generates hydraulic pressure that is approximately proportional to the depressing force. The generated hydraulic pressure is supplied to the wheel cylinders 13aFL, 13aFR, 13aRL, and 13aRR of each wheel via the brake mechanism 13. In response to the driver's brake pedal operation, the pistons of the wheel cylinders 13a of each wheel are pressed against the disc rotors, generating braking forces at each wheel. Note that the vehicle 1 equipped with the vehicle control device 2 may omit the brake booster and master cylinder. In this case, the brake pedal 17 and the brake mechanism 13 may be directly connected, and the brake mechanism 13 may be directly operated when the driver depresses the brake pedal 17.

[0019] Furthermore, when driving assistance or automatic driving is performed in response to an external command from the external control device 3, the vehicle control device 2 controls the brake mechanism 13 and the wheel cylinders 13a of each wheel via the braking control device 13b in response to the input external command. As a result, the vehicle 1 is braked and the desired driving assistance or automatic driving is performed. The braking control device 13b also has the function of converting the amount of operation of the brake pedal 17 by the driver into a brake command and outputting it to the vehicle control device 2 as an external command.

[0020] Next, the steering system of the vehicle 1 will be described. The vehicle 1 includes, as a main part of the steering system, a steering mechanism 14 that applies a steering force to each of the wheels 11. Fig. 1 shows a front steering mechanism 14F that steers the front wheels 11F (left front wheel 11FL, right front wheel 11FR) and a rear steering mechanism 14R that steers the rear wheels 11R (left rear wheel 11RL, right rear wheel 11RR). However, it is not necessary to provide steering mechanisms 14 on both the front and rear wheels; for example, the rear steering mechanism 14R may be omitted.

[0021] When the driver wishes to steer the vehicle 1, the driver operates the steering wheel 18. At this time, the "steering torque" and "steering angle" input by the driver via the steering wheel 18 are detected by the steering torque detection device 18a and the steering angle detection device 18b. The front steering control device 14aF controls the front steering motor 14bF based on the detected steering torque and steering angle to generate an assist torque for steering the front wheels 11F. Similarly, the rear steering control device 14aR controls the rear steering motor 14bR based on the detected steering torque and steering angle to generate an assist torque for steering the rear wheels 11R.

[0022] Furthermore, when driving assistance or automatic driving is performed in response to an external command from the external control device 3, the vehicle control device 2 controls the steering torque of the steering motor 14b via the steering control device 14a. As a result, the vehicle 1 is braked and the desired driving assistance or automatic driving is performed. In this case, the steering wheel 18 may be omitted.

[0023] Next, the suspension system of the vehicle 1 will be described. The vehicle 1 includes, as a key part of the suspension system, suspensions 15 that absorb vibrations and shocks generated at each wheel 11 and improve vehicle body stability and ride comfort. The suspensions 15 are, for example, semi-active suspensions that combine dampers with adjustable viscosity and coil springs. However, the suspensions 15 are also fully active suspensions that combine length-adjustable actuators, dampers, and coil springs, allowing the relative distance between the vehicle body and the wheels 11 to be arbitrarily changed. The vehicle control device 2 not only improves ride comfort and the like by controlling the viscosity of the semi-active suspensions and the length of the full-active suspensions, but also appropriately controls the posture of the vehicle 1 according to the environment.

[0024] 2 is a functional block diagram of the vehicle control device 2. The vehicle control device 2 includes a driver operation amount acquisition unit 20, a vehicle state acquisition unit 21, an external environment data acquisition unit 22, a driver state acquisition unit 23, a surrounding risk determination unit 24, a norm calculation unit 25, an operation amount determination unit 26, a support acceptance determination unit 27, a driving behavior determination unit 28, and an operation amount change unit 29.

[0025] The driver operation amount obtaining unit 20 obtains the driving operation amount of the driver 51 who is driving the vehicle 1. The driving operation amount is, for example, the output value of the stroke sensor 16a when the accelerator pedal 16 is depressed, and the output value of a switch or a pedal force sensor that determines whether the brake pedal 17 is depressed. The driving operation amount may also include output values ​​of the steering torque detecting device 18a and the steering angle detecting device 18b that obtain the force and angle with which the steering wheel 18 is operated.

[0026] The vehicle state acquisition unit 21 acquires vehicle states such as translational and rotational speeds and accelerations occurring in the vehicle. The vehicle state acquisition unit 21 may acquire detection values ​​of longitudinal, lateral, and vertical accelerations, and roll, pitch, and yaw rates from the combined sensor 4, or may calculate (estimate) these from the operation amounts of each actuator, such as the motor 12, the brake mechanism 13, and the steering mechanism 14. The vehicle state acquisition unit 21 may further acquire detection values ​​of roll and pitch angles from information from stroke sensors of the suspensions 15 attached to each wheel, and the vehicle's own position acquired by GNSS.

[0027] The external world data acquisition unit 22 acquires external world data from the external world sensor 19 installed on the host vehicle 1 and determines the position, size, movement speed, etc. of objects (obstacles, etc.) around the host vehicle 1 based on the acquired external world data. Furthermore, when the external world data acquisition unit 22 detects road signs, road paint, traffic lights, etc., it identifies their positions and types and recognizes traffic rules in the area ahead of the host vehicle 1. When cameras are used as these on-board sensors, the types of multiple objects can be identified simultaneously from images captured by the cameras to acquire external world data. A stereo camera using two cameras is particularly advantageous because it can also detect the relative distance and relative speed of moving objects and obstacles. The external world data acquisition unit 22 stores the acquired external world data in a storage device (e.g., RAM) within the vehicle control device.

[0028] The external world data acquisition unit 22 may further include a map information acquisition unit (not shown) that stores or acquires map data in advance via communication, such as data on the shape of the road on which the vehicle 1 is traveling and the location of road paint. In this case, the vehicle state acquisition unit 21 can correct its own position by comparing information such as road paint in the external world data acquired by the external world data acquisition unit 22 with the map data, thereby acquiring its own position with higher accuracy. In this case, the external world data acquisition unit 22 can also acquire more accurate traffic rules from the map information.

[0029] The driver state acquisition unit 23 acquires the driver state, such as the driver's head movement, gaze data, and facial expression, through sensors and input means mounted inside the vehicle 1. The driver information acquired by the driver state acquisition unit 23 is used to calculate a quantitative value of the driver's receptivity to assist control in the assistance acceptance determination unit 27, which will be described later, and to calculate a safe driving level in the driving behavior determination unit 28. The driver state may be used to detect dangerous states, such as the driver being distracted or falling asleep, and to warn the driver.

[0030] The driver state acquisition unit 23 may have a function of identifying an individual from a facial image of the driver by image processing. Generally, the driver's personal identification function is used to realize a function of automatically setting the seat and mirror positions pre-registered for each driver. In this embodiment, in addition to this, the driver state acquisition unit 23 may have a function of realizing appropriate driving assistance based on the driver's attributes identified from the facial image, and the function is also used to change the reference trajectory based on individual driving preference learning in the operation amount change unit 29 described later.

[0031] 3 is a diagram illustrating the processing of the driver state acquisition unit 23. In this diagram, the driver state acquisition unit 23 is installed near the connection point between the windshield and the ceiling, for example, near the position where the rearview mirror is located. In this example, the driver state acquisition unit 23 includes a camera.

[0032] In this case, the driver state acquisition unit 23 detects the state of the driver 51 seated in the front driver's seat. The driver state acquisition unit 23 obtains, for example, a detection result 51P. This detection result 51P estimates the three-dimensional posture of the head of the driver 51 by recognizing facial features such as the eyes, nose, and ears in a facial image of the driver 51 captured by a camera. This estimation can be performed using various known methods, such as OpenPose or Mediapipe. Note that the driver state acquisition unit 23 does not need to include a camera, and may be provided with a sensor that can acquire data that can be used to estimate the posture of the driver's head. For example, the driver state acquisition unit 23 may include a camera that uses not only visible light but also infrared light, or may include LiDAR or the like that can acquire 3D shape data.

[0033] The surrounding risk determination unit 24 uses the external environment data acquired by the external environment data acquisition unit 22 to determine a risk area 54, which is a collection of actual risk areas and potential risk areas. Here, "determination" is synonymous with "extraction," "estimation," and "determination." The actual risk area is calculated using the external environment data detected by the external environment data acquisition unit 22, and is the area where a parked vehicle 52, an object that the host vehicle 1 must avoid by steering or braking while traveling, is located, and its surrounding area. Note that the parked vehicle 52 is merely an example of an obstacle, and various stationary objects, as well as moving objects such as a preceding vehicle, an oncoming vehicle, a pedestrian, or a bicycle, may also be present. The potential risk area is an area where no vehicles or pedestrians are currently detected, but where an obstacle such as a parked vehicle 52 may potentially appear in the future.

[0034] The determined risk area 54 is used to calculate a standard trajectory in the standard calculation unit 25, which will be described later, and to calculate a safe driving degree in the driving behavior determination unit 28. As will be described in detail later, the standard calculation unit 25 calculates a standard trajectory so that the host vehicle 1 does not enter the calculated risk area 54. Furthermore, when the host vehicle 1 is forced to enter the risk area 54, the driving behavior determination unit 28 regards driving so as to enter by sufficiently slowing down as safe driving, and calculates the standard trajectory and the safe driving degree.

[0035] In the following description, when multiple risk regions 54 are calculated, the risk regions 54 are identified by the designations "first" and "second," and the reference numerals are appended with "a" and "b." In other words, there is no essential difference between the first risk region 54a and the second risk region 54b; they simply represent different risk regions 54.

[0036] 4 is a diagram illustrating the processing of the surrounding risk determination unit 24. In FIG. 4, the host vehicle 1 shown on the left side of the figure is traveling to the right on a straight road. A parked vehicle 52, which is an obstacle, is present on the left side in front of the host vehicle 1, and an oncoming vehicle 53 is traveling toward the host vehicle 1 in the opposite lane in front of the host vehicle 1 to the right. Data regarding the parked vehicle 52 and the oncoming vehicle 53 is acquired by the external environment data acquisition unit 22. At this time, the first risk area 54a and the second risk area 54b are determined to be risk areas 54.

[0037] The first risk area 54a is the parked vehicle 52 and its surrounding area. Because an appropriate lateral distance needs to be maintained when the host vehicle 1 passes beside the parked vehicle 52, it is desirable that the first risk area 54a include the side areas of the parked vehicle 52. It is also desirable that the first risk area 54a include the area in front of the parked vehicle 52, i.e., the area on the right side in the figure, as a potential risk area, which is likely to be a blind spot area when viewed from the host vehicle 1.

[0038] The second risk area 54b is an area including the oncoming vehicle 53 and the area in its direction of travel. Because the host vehicle 1 needs to move into the oncoming lane when passing by the parked vehicle 52, the second risk area 54b is set as an area into which the host vehicle 1 is not permitted to enter so as not to obstruct the oncoming vehicle 53's travel. It is desirable to increase or decrease the area of ​​the second risk area 54b in the direction of travel of the oncoming vehicle 53 depending on the speed of the oncoming vehicle 53. As an example of a risk area 54 other than that shown in the figure, for example, the area behind a blind spot at an intersection with poor visibility is calculated as a risk area. Because moving objects such as bicycles and pedestrians may suddenly appear in this area, the host vehicle 1 needs to keep a distance from this area or slow down when entering the area.

[0039] So far, we have explained a method for calculating the risk area 54 using the external world data acquired by the external world data acquisition unit 22, but a blind spot area identified using the map information described above may also be set as the risk area 54. Furthermore, data on an area where many traffic accidents have occurred in the past may also be acquired, and this area may be set as the risk area 54.

[0040] The norm calculation unit 25 calculates a normative driving operation amount, for example, a target route along which the vehicle 1 should travel, as a norm trajectory 55 based on the current position and travel angle of the vehicle 1 acquired by the vehicle state acquisition unit 21, the external environment data acquired by the external environment data acquisition unit 22, and the risk area 54 determined by the surrounding risk determination unit 24. The norm trajectory 55 is used by the operation amount determination unit 26, which will be described later, to calculate an assist operation amount by comparing it with the driving operation amount of the driver 51. Note that the norm trajectory 55 may include speed.

[0041] In the following description, when a plurality of normal trajectories 55 are calculated, a "first" or a "second" is added to distinguish each normal trajectory 55, and an "a" or a "b" is added to the reference numeral. In other words, there is no essential difference between the first normal trajectory 55a and the second normal trajectory 55b, and each simply means that they are different normal trajectories 55.

[0042] 5 and 6 are diagrams illustrating the behavior processing of the norm calculation unit 25. In Fig. 5, a parked vehicle 52 is stopped on the left side in front of the host vehicle 1 traveling on the right side of the figure. In this case, the first risk area 54a is set to the parked vehicle 52 and its surrounding area. The norm trajectory 55 is calculated as a trajectory that maintains a sufficient lateral distance from the first risk area 54a.

[0043] On the other hand, in FIG. 6 , in addition to the parked vehicle 52 shown in FIG. 5 , an oncoming vehicle 53 is approaching the host vehicle 1 from the front right. In FIG. 6 , in addition to the first risk area 54a set around the parked vehicle 52, a second risk area 54b including the oncoming vehicle 53 and its area in its direction of travel is calculated. In this case, if the first standard trajectory 55a is calculated in the same manner as in FIG. 5 , it would be undesirable because the host vehicle would enter the second risk area 54b. Therefore, the second standard trajectory 55b, which takes into account the presence of the oncoming vehicle 53, is calculated as a path closer to the parked vehicle 52 than the first standard trajectory 55a. As will be described later in the explanation of the operation amount determination unit 26, in this case the target speed (not shown) is calculated to be lower than in the case of FIG. 5 .

[0044] Although only one second standard trajectory 55b is illustrated in FIG. 6 as the preferred standard trajectory 55, multiple preferred standard trajectories 55 or standard trajectories 55 with a certain width may be calculated. Generally, a trajectory for properly passing through a traffic environment is not necessarily uniquely determined, and an ideal traveling trajectory has a certain width. The width of the trajectory may be predetermined, or the width may vary depending on the position, with the left and right limits of the traveling direction being the width of the trajectory. However, for simplicity, in the following explanation, the standard trajectory 55 will be depicted and described as a single thin line.

[0045] 5 and 6 are described on the assumption that the risk area 54 has already been calculated, but the operation of the norm calculation unit 25 does not require the calculation of the risk area 54. For example, the norm calculation unit 25 may use external environment data to identify obstacles present around the vehicle 1, and calculate the norm trajectory 55 by connecting positions that are at a distance equal to or greater than a predetermined distance from the obstacles.

[0046] The operation amount determination unit 26 calculates an assist operation amount, which is an operation amount of each actuator for assisting the driver's driving operation, by comparing the standard trajectory 55 with the driver's driving operation amount. The method for calculating the assist operation amount is not particularly limited, but can be calculated, for example, in the following three steps. First, the standard trajectory 55 is set as a target driving path for the vehicle 1, and a steering angle that follows the target driving path is calculated as a standard steering angle. Second, an actual steering angle is obtained as a driving operation amount of the driver 51. Third, a torque (steering assist torque) proportional to the deviation between the standard steering angle and the actual steering angle is generated by the steering motor 18d. In this case, the driver performs driving while feeling a reaction force in the direction of the standard steering angle, and it is expected that the driver's actual steering angle will naturally approach the standard steering angle. Such a reaction torque calculation method can be expressed as the following Equation 1.

[0047] Ta=Ka(θref−θd) (Formula 1)

[0048] Here, Ta is the assist torque generated by the steering motor 18d, Ka is a proportional gain that determines the strength of the assist, θref is the standard steering angle, and θd is the actual steering angle. A typical steering motor also generates an assist torque that reduces the self-aligning torque, which is a reaction force generated on the tires when the vehicle 1 is steered. In the following description of this embodiment, it is assumed that a torque for assisting this self-aligning torque is always generated, and this torque will not be specifically described or illustrated. Below, only the steering assist torque that is additionally generated to cause the driver's operation to follow the standard trajectory will be described as an example.

[0049] The standard steering angle can be calculated based on at least one of a lateral deviation and an angular deviation, for example. The lateral deviation is the deviation of the current position of the host vehicle 1 from the standard trajectory 55. The accuracy deviation is the deviation between the tangential direction of the standard trajectory 55 near the host vehicle and the traveling angle of the host vehicle 1. A known method is the "forward gaze model," in which a specific point on an extension of the traveling direction of the host vehicle 1 is set as a forward gaze point, and the deviation between the forward gaze point and the closest point on the standard trajectory 55 is used as the standard total steering angle.

[0050] 7 to 9 are diagrams showing examples of the operation of the operation amount determination unit 26. Each of FIGS. 7 to 9 shows a different example. As shown in FIG. 7( a), a parked vehicle 52 is present on the front left side of the host vehicle 1. FIG. 7 shows an example of calculation in which a reaction torque is generated by the steering motor 18d as the steering assist torque 57. For simplicity, FIG. 7 shows an example of calculation of the steering assist torque 57 proportional to the lateral deviation of the current position of the host vehicle 1 from the reference trajectory 55, and represents the difference in the driving methods of two drivers A and B and the difference in the steering assist torque generated at that time.

[0051] 7(a), the dashed line indicates the standard trajectory 55, the solid line indicates a first actual operation trajectory 56a which is a trajectory traveled by driving by driver A, and the dashed-dotted line indicates a second actual operation trajectory 56b which is a trajectory traveled by driving by driver B. Both the first actual operation trajectory 56a and the second actual operation trajectory 56b pass through a route closer to the parked vehicle 52 than the standard trajectory 55. Fig. 7(b) shows the transition of the steering assist torque over time, with the solid line indicating the steering assist torque corresponding to the first actual operation trajectory 56a and the dashed-dotted line indicating the steering assist torque corresponding to the second actual operation trajectory 56b.

[0052] All steering assist torques 57 are calculated to the right as viewed from the traveling direction of the vehicle 1, i.e., as negative values. Because the second actual operation trajectory 56b of driver B is farther away from the standard trajectory 55 than the first actual operation trajectory 56a of driver A, the magnitude of the steering assist torque 57b is calculated to be greater than that of 57a. In addition, the shapes of both are proportional to the lateral deviation between the standard trajectory and the actual steering trajectory. By calculating the steering assist torque 57 in this manner, the driver will feel a greater steering reaction force as he or she drives further away from the standard trajectory 55, in other words, closer to the parked vehicle 52.

[0053] FIG. 8 shows an example in which a parked vehicle 52 is present on the left side in front of the host vehicle 1 on a narrow road, and there is insufficient space for the host vehicle 1 to move to the right to avoid the parked vehicle 52. In this example, the driver's actual operation trajectory 56 does not deviate significantly from the reference trajectory 55, as shown by the solid line in FIG. 8(a). At this time, the steering assist torque 57 is always close to zero, as shown in FIG. 8(b). In this case, the driving assistance in this embodiment is centered on speed control. That is, as shown in FIG. 8(c), a reference speed 65, which is a reference for the speed, is calculated in the same way as the reference trajectory 55, which is a reference for the driving route.

[0054] This reference speed 65 is calculated as a speed that allows for sudden braking to avoid contact if, for example, a person suddenly jumps out from inside or behind the parked vehicle 52. Then, as shown in FIG. 8( d ), a deceleration assist 67 is calculated based on the deviation from the actual speed 66 determined by the driver's actual operation. Here, an example is shown in which the reference speed 65 is calculated in terms of acceleration fluctuation value, and a negative value is calculated because of the deceleration direction. Based on the acceleration fluctuation value, the vehicle 1 is decelerated by, for example, automatically operating the braking control device 13 b. However, if the accelerator pedal 16 or the brake pedal 17 is equipped with an actuator such as a motor, the following operation may be performed instead of the operation of the braking control device 13 b. That is, the actuator provided in the accelerator pedal 16 or the brake pedal 17 may assist the driver in releasing the accelerator pedal or applying the brake by applying a force in the direction of releasing the accelerator pedal 16 or pressing the brake pedal 17.

[0055] 9 shows an example of the behavior of the operation amount determiner 26 when multiple reference trajectories 55 are calculated or when the reference trajectory 55 has a width. The situation shown in FIG. 9 is the same as that shown in FIG. 7, and a parked vehicle 52 is present on the front left side of the host vehicle 1. In FIG. 9(a), the reference trajectory 55 has a width, and a first reference trajectory 55a closest to the parked vehicle 52 and a second reference trajectory 55b farthest from the parked vehicle 52 are depicted. If the driver's actual operation trajectory 56 passes between the first reference trajectory 55a and the second reference trajectory 55b, no steering assist torque 57 is generated. The actual operation trajectory 56 is shown by a solid line in FIG. 9 and intersects with the first reference trajectory 55a.

[0056] At this time, the transition of the steering assist torque over time is as shown in Figure 9(b). As shown in Figure 7, when standard trajectory 55 is a single line with no width, it is calculated as steering assist torque 57. However, when standard trajectory 55 has width as described above, the steering assist torque is generated only for the time when standard trajectory 55 deviates from first standard trajectory 55a on the side of parked vehicle 52, as shown by the wide steering assist torque 57c indicated by the solid line, and the magnitude of this assist torque is smaller overall than steering assist torque 57 indicated by the dashed line.

[0057] The feature of this method of calculating the steering assist torque can be realized even when there is only one standard trajectory 55 by setting a dead zone for the deviation as shown in Equation 2, for example.

[0058]

[0059] Here, Ta is the assist torque generated by the steering motor 18d, Ka is a proportional gain that determines the strength of the assist, θref is the reference steering angle, θd is the actual steering angle, and Δθ is the angle of the dead band.

[0060] The assistance acceptance determination unit 27 determines an acceptance quantitative value that indicates whether the driver accepts the driving assistance provided by the assist operation amount calculated by the operation amount determination unit 26. For this determination, the assistance acceptance determination unit 27 uses at least one of the driver's driving operation amount acquired by the driver operation amount acquisition unit 20, the driver state acquired by the driver state acquisition unit 23, and the assist operation amount calculated by the operation amount determination unit 26.

[0061] Here, acceptance of assistance refers to a state in which the driver does not feel uncomfortable or anxious about the driving assistance, feels that the assistance is in line with the driver's driving intentions and preferences, feels that the driver is able to drive the vehicle 1 according to his or her own will despite the driving assistance being provided, etc. The output of the assistance acceptance determination unit 27 may be, for example, a binary determination of whether the driver has accepted the driving assistance or not, or a continuous quantitative value indicating the level of acceptance. In the following explanation, an example of calculation as the latter quantitative value will be described.

[0062] 10 to 13 are diagrams illustrating the operation of the support acceptance determination unit 27. FIGS. 10 and 11 show examples in which the passivity is different in the same situation. In both FIGS. 10 and 11, a parked vehicle 52 is present on the front left side of the host vehicle 1. In both FIGS. 10 and 11, the support acceptance determination unit 27 determines the acceptance from the waveform of the driver's own steering torque relative to the steering assist torque. FIG. 10 shows the case of driver A, who has a high acceptance level, and FIG. 11 shows the case of driver B, who has a low acceptance level. In both FIGS. 10 and 11, (a) shows the traveling trajectory of the host vehicle, (b) shows the time-series change in the driver steering torque, (c) shows the time-series change in the steering assist torque, and (d) shows the time-series change in the acceptance quantitative value.

[0063] First, in Fig. 10(a), driver A traveled along a first actual operation trajectory 56a with respect to a standard trajectory 55. Since the first actual operation trajectory 56a was slightly to the side of the parked vehicle 52 with respect to the standard trajectory 55, the first steering assist torque 57a is calculated as a direction away from the parked vehicle 52, i.e., a negative value. As shown in Fig. 10(b), the driver steering torque 58a becomes a negative value because the driver steers to the right by his / her own will, and then changes to a positive value when the driver steers to the left to return to the original lane.

[0064] As shown in Figure 10(c), the first steering assist torque 57a is generated in the same direction as the driver during the time between the two-dot chain lines when the driver is steering to the right. The support acceptance determination unit 27 determines that the driver is accepting the assistance when the positive and negative signs of the driver's steering torque and the steering assist torque match, or when the magnitude of the steering assist torque does not increase significantly. As shown in Figure 10(d), the support acceptance determination unit 27 calculates the first acceptance quantitative value 59a as a high value during the time between the two-dot chain lines when the steering assist torque is generated.

[0065] Similarly, in Fig. 11(a), driver B traveled along a second actual operation trajectory 56b with respect to the standard trajectory 55. Since this second actual operation trajectory 56b was significantly closer to the parked vehicle 52 with respect to the standard trajectory 55, second steering assist torque 57b was calculated in a direction away from the parked vehicle 52, i.e., as a negative value. The magnitude of this second steering assist torque 57b is larger than the first steering assist torque 57a for driver A. However, driver B does not approve of traveling along the standard trajectory 55 at a location significantly away from the parked vehicle 52, and generates driver steering torque 58b in a direction against the steering assist torque, i.e., in the positive direction, as shown in Fig. 11(b).

[0066] The driver steering torque 58b spends most of the time in a direction opposite in sign to the second steering assist torque 57b shown in Figure 11(c), indicating that the driver is deliberately attempting to steer in a direction that cancels out the steering assist provided by the driving assist. The assist acceptance determination unit 27 determines that the driver is accepting the assist when the driver steering torque and the steering assist torque have opposite signs or when the steering assist torque is large. As shown in Figure 11(d), the assist acceptance determination unit 27 calculates the second receptivity quantitative value 59b as a low value during the time between the two-dot chain lines when the second steering assist torque 57b is generated.

[0067] 10 and 11, Fig. 12 shows an example in which a parked vehicle 52 is present on the left side in front of the host vehicle 1. However, unlike Figs. 10 and 11, Fig. 12 judges the acceptance level from the waveform of the driver's steering angle or the driver's steering angular velocity, which is the time derivative of the driver's steering angle. In this figure, examples of driver A with high acceptance and driver B with low acceptance are shown overlapping each other.

[0068] In FIG. 12( a), driver A is traveling on a first actual operation trajectory 56a with respect to a standard trajectory 55. Since the first actual operation trajectory 56a generally coincides with the standard trajectory 55 and is slightly closer to the parked vehicle 52, the steering assist torque is calculated as a direction away from the parked vehicle 52, i.e., a negative value, as in FIG. 10( c). At this time, as shown in FIG. 12( b), driver A's driver steering angle 60a becomes a negative value because the driver steers to the right when the driver starts to avoid the parked vehicle 52, and then changes to a positive value because the driver steers to the left to return to the original lane. Driver A has a high degree of acceptance of assistance and the assist torque itself is small, so the time series change of the driver steering angle 60a is smooth. Therefore, the steering angular velocity 61a obtained by differentiating the steering angle with respect to time changes smoothly as shown in FIG. 12( c), and the absolute value does not increase much. If the time transition is as described above, the support acceptance determination unit 27 calculates the first acceptance quantitative value 59a as a high value as shown in FIG. 12(d), and determines that the driver A accepts the support.

[0069] As shown in FIG. 12( a), driver B is traveling on a second actual operation trajectory 56b that moves almost straight near the parked vehicle 52, not along the standard trajectory 55. Because the deviation between the standard trajectory 55 and the second actual operation trajectory 56b is large, the steering assist torque is calculated as a negative value, i.e., in a direction away from the parked vehicle 52, as in FIG. 11( c), and its magnitude is greater than the steering assist torque for driver A. At this time, as shown in FIG. 12( b), the driver steering angle 60b fluctuates near 0 because the vehicle is traveling almost straight near the parked vehicle 52, and fluctuates to resist the assist amount, fluctuating between positive and negative in a short period. As a result, the driver steering angular velocity 61b, which is the time derivative of the driver steering angle 60b, changes significantly as shown in FIG. 12( c). With such a time transition, the assistance acceptance determination unit 27 calculates the second acceptance quantitative value 59b as a low value, as shown in FIG. 12( d). That is, the support acceptance determination unit 27 determines that the driver B does not accept the support. In this way, the support acceptance determination unit 27 determines the acceptance level based on the relationship between the assist operation amount and the driving operation amount, based on criteria such as whether the driver is steering in the same direction as the support and whether the driver is not wavering when receiving the support.

[0070] FIG. 13 is a diagram illustrating the process in which the support acceptance determination unit 27 determines the acceptance level using data related to the driver's line of sight. In other words, in FIG. 13, the support acceptance determination unit 27 uses statistical features of the line of sight data as the driver state. This diagram is a conceptual diagram showing the behavior of the host vehicle 1 in the example of FIG. 12 from the time when the host vehicle 1 starts to avoid the parked vehicle 52, that is, from time 0 in FIG. 12(b) to approximately the time when the driver steering angle 60a becomes minimum. FIGS. 13(a) and 13(b) each show a driver gaze point 62 at which driver A and driver B gaze during a predetermined period. The driver gaze point 62 can also be considered to be an area in which the range in which the center of each driver's line of sight moves is displayed superimposed on the driver's field of view.

[0071] 13 shows the point at which the host vehicle 1 has started to avoid the parked vehicle 52, so the parked vehicle 52 is shown to the left and in front. At this time, driver A and driver B have in common the fact that they are primarily gazing at the planned forward direction of travel, which includes the parked vehicle 52. However, there are the following differences between the first gaze point 62a, which is driver A's gaze point, and the second gaze point 62b, which is driver B's gaze point. That is, compared to the first gaze point 62a, the second gaze point 62b is gazing closer to the host vehicle 1, and the second gaze point 62b is wider than the first gaze point 62a, so driver B's line of sight moves frequently.

[0072] It is generally known that when a driver feels uncomfortable or anxious about driving, they tend to gaze closer to the planned travel area of ​​the vehicle, and blink and saccade (eye movement) tend to increase. Therefore, when the gaze point has the above-mentioned characteristics, the support acceptance determination unit 27 calculates the first acceptance quantitative value 59a of driver A as a high value and the second acceptance quantitative value 59b of driver B as a low value, as shown in Figure 13(c).

[0073] The driving behavior determination unit 28 calculates the safe driving level 64 of the driver using the risk area 54 determined by the surrounding risk determination unit 24 and data related to the driver. The data related to the driver is at least one of the driver's driving operation amount acquired by the driver operation amount acquisition unit 20 and gaze point data among the driver states acquired by the driver state acquisition unit 23. Specifically, the driving behavior determination unit 28 calculates the safe driving level 64 based on criteria such as whether the driver's driving behavior provides an appropriate margin for the risk area 54, whether the driver is slowing down, whether the driver is paying attention to the risk area, etc. The safe driving level 64 may be, for example, a binary judgment of whether the driver's driving behavior is safe or not, or may be a continuous quantitative value. The following explanation will be given taking the latter case of calculation as a quantitative value as an example.

[0074] In the case where the safe driving level 64 is a binary value, when the safe driving level 64 is "safe," it is judged to be "above a predetermined threshold" or "greater than a predetermined threshold." In this case, when the safe driving level 64 is "unsafe," it is judged to be "below a predetermined threshold" or "below a predetermined threshold."

[0075] 14 to 16 are diagrams illustrating the operation of the driving behavior determination unit 28. In FIG. 14( a), a parked vehicle 52 is present on the front left side of the host vehicle 1, and a risk area 54 caused by the parked vehicle 52 is set. A first actual operation trajectory 56a, which is the trajectory operated by driver A, avoids the risk area 54, in other words, keeps a distance from the risk area 54. A second actual operation trajectory 56b, which is the trajectory operated by driver B, passes near the risk area 54. FIG. 14( b) illustrates an example of calculating the quantitative value of the safe driving degree. Specifically, a first safe driving degree 64a, which is the safe driving degree of driver A, and a second safe driving degree 64b, which is the safe driving degree of driver B, are shown.

[0076] This figure shows an example in which a risk margin 63, which is the distance between a risk area 54 and an actual operation trajectory 56, is used as the safe driving level. The time trends of the first safe driving level 64a and the second safe driving level 64b are the same as the time trends of the first risk margin 63a and the second risk margin 63b. In this calculation method, a driving behavior in which a driver passes a risk subject such as a parked vehicle 52 at a large lateral distance is determined to be safe driving.

[0077] 15 is a diagram showing an example of a case where there are multiple risk areas in a calculation method of a safe driving level 64 similar to that shown in FIG. 14. In this example, the minimum value of the risk margin for the multiple risk areas is used to calculate the safe driving level 64. As shown in FIG. 15( a), in addition to a parked vehicle 52 on the left front side of the host vehicle 1, an oncoming vehicle 53 is approaching the host vehicle 1 from the front right. In this example, driver A is driving a first actual operation trajectory 56a that is substantially the same as that shown in FIG. 14, and driver B is driving a second actual operation trajectory 56b that is substantially the same as that shown in FIG. 14.

[0078] The first actual operation trajectory 56a has a large risk margin with the first risk area 54a centered on the parked vehicle 52, but a small risk margin with the second risk area 54b centered on the oncoming vehicle 53. The second actual operation trajectory 56b has a medium risk margin with both the first risk area 54a and the second risk area 54b.

[0079] 15(b) shows the change in safe driving level over time. This figure shows a first safe driving level 64a corresponding to the first actual operation trajectory 56a and a second safe driving level 64b corresponding to the second actual operation trajectory 56b. Immediately after time 0, when rightward steering to avoid the parked vehicle 52 is initiated, the first safe driving level 64a exceeds the second safe driving level 64b. However, the magnitude relationship is subsequently reversed due to the influence of the second risk area 54b caused by the oncoming vehicle 53, and the second safe driving level 64b remains higher for the majority of the time.

[0080] 14 and 15 , it can be seen that in cases where a parked vehicle 52 is avoided, a driving behavior that maintains a large lateral distance from the parked vehicle 52 is not necessarily determined to be safe. The driving behavior determination unit 28 evaluates the degree of safe driving as high when the driving is safe and maintains a comprehensive margin for multiple risk areas.

[0081] Figure 16 shows an example in which the vehicle speed is further taken into consideration when calculating the safe driving degree in the situation shown in Figure 15. In Figure 16, there is a parked vehicle 52 and an oncoming vehicle 53, just like in Figure 15(a), and in this example, both Driver A and Driver B are traveling on the second actual operation trajectory 56b in Figure 15(a). Therefore, they have the same second risk margin 63b.

[0082] 16(b) shows the time progression of the reference speed 65 obtained from the reference trajectory 55, and the first actual speed 66a and the second actual speed 66b, which are the actual speeds of driver A and driver B, respectively. As described with reference to FIG. 8, the reference speed 65 is calculated as a speed that allows the driver to brake suddenly to avoid contact when a person suddenly appears from inside or behind the parked vehicle 52, for example. The first actual speed 66a of driver A is even slower than the reference speed 65, and can be considered to be driving with greater consideration for safety. On the other hand, the second actual speed 66b of driver B is faster than the reference speed 65, and driver B's driving behavior is more difficult to deal with potential risks, such as a person suddenly appearing from behind the parked vehicle 52, compared to driver A.

[0083] 16(c), when the actual speed 66 is equal to or less than the standard speed 65, the safe driving level 64 is at its maximum value, and the safe driving level 64 is calculated to be a smaller value the higher the actual speed 66 is compared to the standard speed 65. Therefore, the first safe driving level 64a of driver A is always at its maximum value, and the second safe driving level 64b of driver B is smaller than the first safe driving level 64a. In this way, it is desirable to calculate the safe driving level 64 based not only on the margin for the risk area but also on the passing speed near the risk.

[0084] However, for simplicity, in FIG. 16 , the explanation is given on the assumption that the second risk area 54b caused by the oncoming vehicle 53 is statically determined, but in reality, the oncoming vehicle 53 moves toward the host vehicle 1 over time. Therefore, as in the example shown in FIG. 16 , when the driver A drives at a speed slower than the standard speed 65, the first risk margin 63a between the second actual operation trajectory 56b and the second risk area 54b may be smaller than shown in the figure. In other words, passing through at an unnecessarily low speed is not necessarily safe driving, and depending on the situation, the safest driving may be to temporarily stop in front of the parked vehicle 52, wait for the oncoming vehicle 53 to pass, and then steer to the right. In light of these, it is desirable that the safe driving degree be calculated based on various criteria.

[0085] Up to this point, an example has been shown in which the safe driving level 64 is calculated based on the amount of driving operation by the driver. However, as mentioned above, the safe driving level 64 may also be determined using information on the gaze point among the driver states acquired by the driver state acquisition unit 23. For example, in Fig. 13, both driver A and driver B are appropriately gazing at the parked vehicle 52, and from this perspective, they can be considered to be appropriately gazing at the risk object. If driver C, who is barely gazing at the parked vehicle 52, is driving, the safe driving level 64c of this driver is calculated to be lower than the first safe driving level 64a and the second safe driving level 64b of driver A and driver B.

[0086] When the acceptability quantitative value calculated by the assistance acceptance determination unit 27 is low, the operation amount change unit 29 changes a parameter to reduce the magnitude of the assist operation amount and leaves the driving to the driver's own discretion. The parameter for reducing the magnitude of the assist operation amount is, for example, the assist gain Ka in Equation 1 and Equation 2 in the operation amount determination unit 26. By instructing the operation amount determination unit 26 to reduce this assist gain Ka, it is possible to prevent a strong assist operation amount from being applied to the driver, which would lead to a sense of discomfort, when a deviation occurs between the reference trajectory 55 calculated by the system and the driver's driving intention. In this case, as will be described later, it is necessary to prevent the driver's driving behavior from changing in an unsafe direction as a result of the reduction in the assist operation amount. Therefore, the operation amount change unit 29 determines whether to reduce the magnitude of the assist operation amount and the amount of reduction, taking into account the safe driving degree calculated by the driving behavior determination unit 28.

[0087] 17 and 18 are diagrams illustrating the operation of the operation amount change unit 29. Here, as an example of changing the assist operation amount, a method of changing the value of the assist gain Ka in the above-mentioned Formula 1 and Formula 2 will be described. In Fig. 17(a), a parked vehicle 52 is present on the left side in front of the host vehicle 1, and a reference trajectory 55, a first actual operation trajectory 56a which is the trajectory operated by driver A, and a second actual operation trajectory 56b which is the trajectory operated by driver B are shown.

[0088] 17(b) to 17(e) show time-series changes in the safe driving level 64, the acceptability quantitative value 59, the assist gain Ka, and the steering assist torque 57. In FIGS. 17(b) to 17(e), the horizontal direction indicates time change, and the time in the vertical direction matches between different figures. Specifically, the two-dot chain line running through FIGS. 17(b) to 17(e) indicates the same time. FIG. 17(b) shows a first safe driving level 64a, which is the safe driving level 64 of driver A, and a second safe driving level 64b, which is the safe driving level 64 of driver B. The calculation method for the safe driving level 64 is the same as in FIG. 14, and the first safe driving level 64a has a higher value than the second safe driving level 64b.

[0089] As shown in Fig. 17(a), the actual operation trajectories 56 of driver A and driver B do not match the reference trajectory 55, and as shown in Fig. 17(c), the acceptability quantitative values ​​59 of both drivers decrease. An acceptability threshold 68, which is a threshold value for acceptability, is stored in the operation amount change unit 29. In Fig. 17, the time when the acceptability quantitative values ​​59 of both drivers fall below the acceptability threshold 68 is indicated by a two-dot chain line. As shown in Fig. 17(d), the first assist gain 69a, which is the assist gain Ka for driver A, decreases after this time, but the second assist gain 69b, which is the assist gain Ka for driver B, remains constant after this time.

[0090] The difference between the first assist gain 69a and the second assist gain 69b is due to the difference in the magnitude of the safe driving level 64. The operation amount change unit 29 wants to reduce the assist gain Ka because the acceptability quantitative value 59 of both drivers has fallen below the acceptability threshold 68, but because the safe driving level 64 of driver B is lower than a threshold (not shown), safety is given priority and the assist gain Ka of driver B is not changed. Because driver A's safe driving level 64 is sufficiently high, the operation amount change unit 29 reduces the assist gain Ka of driver A.

[0091] 17(e), the first steering assist torque 57a for Driver A decreases after the time indicated by the two-dot chain line compared to the first initial steering assist torque 57a' when the first assist gain 69a remains unchanged. Since the second assist gain 69b for Driver B remains unchanged, there is no sudden change in the second steering assist torque 57b at the time indicated by the two-dot chain line. This is because the second safe driving level 64b for Driver B is calculated to be low at the time indicated by the two-dot chain line, and priority is given to bringing the vehicle closer to the reference trajectory 55 rather than leaving the driving judgment to Driver B.

[0092] FIG. 18 is a diagram showing the operation of the operation amount change unit 29 when multiple acceptance thresholds 68 are set. In the example shown in FIG. 17, only one acceptance threshold 68 is set, but multiple acceptance thresholds 68, such as a first acceptance threshold 68a and a second acceptance threshold 68b, may be set. FIG. 18(a) shows the behavior of driver B shown in FIG. 17(a). The second acceptance threshold 68b is smaller than the first acceptance threshold 68a. When the user's acceptance quantitative value 59 becomes smaller than the second acceptance threshold 68b, the operation amount change unit 29 reduces the assist gain Ka even if the value of the safe driving level 64 is small.

[0093] At the time indicated by the two-dot chain line, the second receptivity quantitative value 59b of driver B becomes smaller than the first receptivity threshold 68a, but the second safe driving level 64b is smaller than a threshold (not shown), so the operation amount change unit 29 does not change the assist gain Ka. However, at the time indicated by the dashed line, the second receptivity quantitative value 59b becomes smaller than the second receptivity threshold 68b, so the operation amount change unit 29 reduces the assist gain Ka of driver B. Therefore, the steering assist torque 57 of driver B becomes the second steering assist torque 57b instead of the second initial steering assist torque 57b', and its magnitude decreases after the time indicated by the dashed line.

[0094] As described with reference to Figures 17 and 18, in many cases, the assist gain is reduced only when the safe driving level is high, as in Figure 17. However, as in Figure 18, when the acceptability quantitative value 59 is very low, the assist gain Ka may be reduced even if the safe driving level is lower than the threshold. This is because the vehicle control device 2 is a system that operates under the responsibility of each driver, and there are cases where it is required to respect the driver's driving intention. In other words, if the driver operates the vehicle strongly against the assistance, there are cases where the system overrides the assistance and leaves the vehicle to the driver's responsibility for driving. Furthermore, the risk area determined by the surrounding risk determination unit 24 is not always appropriate, and the reference trajectory 55 does not always calculate a trajectory that the driver considers appropriate for the road environment in question. Therefore, it is also possible to set the operation amount change unit 29 in this way.

[0095] The first embodiment described above provides the following advantageous effects. (1) The vehicle control device 2 is mounted on the vehicle 1 driven by a driver. The vehicle control device 2 includes a surrounding risk determiner 24 that determines a risk area 54, which is a high-risk area present around the vehicle, based on external environment information; a norm calculation unit 25 that calculates a normative driving operation amount based on the risk area 54, the external environment information, and the vehicle state; an operation amount determiner 26 that determines an assist operation amount based on a first parameter that is an assist gain Ka that determines the magnitude of an assist operation amount for assisting the driver's driving operation, the normative driving operation amount, and the driver's driving operation amount; an assistance acceptance determiner 27 that calculates an acceptability quantitative value 59 that indicates the driver's degree of acceptability to the assist operation amount based on at least one of the assist operation amount, the driving operation amount, and a driver state that indicates the driver's state; an operation amount changer 29 that changes the first parameter so that the assist operation amount decreases as the acceptability quantitative value 59 decreases; and a driving behavior determiner 28 that calculates a safe driving level 64, which is an index of the safety of the driver's driving operation of the vehicle, based on the driving operation amount and the risk area. 17 and 18 , the operation amount changing unit 29 further changes the first parameter based on the safe driving level 64. Therefore, the amount of assistance, i.e., the amount of assist operation, can be reduced for a driver who drives the vehicle 1 safely and has a low level of support acceptance. Furthermore, assistance can be continued for a driver with a low level of safe driving without reducing the amount of assist operation.

[0096] (2) The standard driving operation amount calculated by the standard calculation unit 25 includes at least one of the vehicle's travel route, speed, steering amount, and acceleration / deceleration amount.

[0097] (3) The norm calculation unit 25 calculates the norm driving operation amount so that the distance to the risk area increases or the speed when passing near the risk area decreases, thereby guiding the driving of the vehicle 1 to a safer direction.

[0098] (4) The operation amount determiner 26 determines the assist operation amount based on the deviation between the reference operation amount and the driving operation amount. Therefore, the greater the difference between the reference operation amount and the driving operation amount, the greater the assist operation amount that can be obtained.

[0099] (5) The operation amount determiner 26 determines an assist gain Ka, which is a proportional gain, and calculates at least one of the steering assist torque and the acceleration fluctuation value by multiplying the deviation between the reference operation amount and the operation amount by the proportional gain.

[0100] (6) The reference calculation unit 25 calculates multiple reference driving operation amounts or sets a range of reference driving operation amounts, so that a more realistic reference trajectory 55 can be set instead of a single narrow line.

[0101] (7) The operation amount determiner 26 determines the assist operation amount by setting a dead zone for the deviation between the standard operation amount and the operation amount as shown in Equation 2. Therefore, even if there is only one thin standard trajectory 55, some deviation can be tolerated in accordance with reality.

[0102] (8) The assistance acceptance determination unit 27 calculates the acceptance quantitative value based on the difference in sign between the assist operation amount and the driving operation amount, as shown in Fig. 10. This makes it easy to calculate the acceptance quantitative value.

[0103] (9) The assistance acceptance determination unit 27 calculates the acceptance quantitative value based on the variance in the driving operation amount. Therefore, the acceptance quantitative value can be calculated using only the driving operation amount without referring to the assist operation amount.

[0104] (10) The support acceptance determination unit 27 acquires gaze data of the driver as the driver state as shown in Fig. 13 and determines the acceptance quantitative value based on the gaze data. Therefore, the acceptance can be calculated using the physiological characteristics of the driver.

[0105] (11) The driving behavior determination unit 28 calculates the degree of safe driving based on at least one of the distance between the risk area and the vehicle and the speed of the vehicle when passing near the risk area.

[0106] (12) When the safe driving level is greater than a predetermined threshold, the operation amount change unit 29 changes the assist gain Ka so that the assist operation amount is smaller than when the safe driving level is equal to or less than the predetermined threshold. Therefore, when the safe driving level is greater than the predetermined threshold, the assist gain Ka can be reduced.

[0107] (Variation 1) In the first embodiment described above, a plurality of operations of the acceptability quantitative value 59 have been described with reference to Figures 10 to 13. The acceptability quantitative value 59 may execute only one of the methods described in the first embodiment.

[0108] (Variation 2) In the first embodiment described above, the standard trajectory 55 is a target route along which the host vehicle 1 should travel, or a combination of the target route and speed. However, the standard trajectory 55 may include at least one of the vehicle's travel route, speed, steering amount, and acceleration / deceleration amount. For example, if the standard trajectory 55 is only the steering amount, the standard trajectory 55 is an appropriate steering amount for each position of the host vehicle 1.

[0109] In the first embodiment described above, the operation amount determiner 26 calculates the steering assist torque by multiplying the deviation between the reference operation amount and the operation amount by a proportional gain. However, the operation amount determiner 26 may calculate the acceleration fluctuation value by multiplying the deviation between the reference operation amount and the operation amount by a proportional gain, or may calculate both the steering assist torque and the acceleration fluctuation value.

[0110] 16 , the safe driving degree is calculated by the driving behavior determination unit 28 taking into consideration not only the distance between the risk area and the vehicle but also the speed of the vehicle 1 when the vehicle 1 passes near the risk area 54. However, the driving behavior determination unit 28 may calculate the safe driving degree using only the speed of the vehicle 1 when the vehicle 1 passes near the risk area 54.

[0111] (Variation 5) The vehicle control device 2 may further include a risk reliability determination unit that acquires the accuracy or reliability of acquisition of external data or risk areas. In this case, the operation amount change unit 29 changes the assist gain 69 so that the assist operation amount is smaller when the risk reliability is low than when the risk reliability is high. Examples of when the risk reliability decreases include when the weather worsens, such as rain, snow, or fog, or when a temporary sensor failure or malfunction makes it difficult for the sensor to grasp the situation around the vehicle 1. Furthermore, it is generally difficult to predict the future behavior of moving objects such as pedestrians and bicycles. Therefore, in road environments where these moving objects are densely mixed, the reliability of the risk area calculated by the surrounding risk determination unit 24 may be set low and the assist gain 69 may be reduced to leave driving to the driver.

[0112] - Second embodiment - A second embodiment of a vehicle control device will be described with reference to Figures 19 to 21. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and differences will be mainly described. Points that are not particularly described are the same as those in the first embodiment. This embodiment differs from the first embodiment mainly in that the standard trajectory 55 is changed to suit the driving characteristics of the driver.

[0113] In the first embodiment, the magnitude of the assist operation amount is reduced for a driver who is driving safely but whose receptivity has decreased, thereby suppressing the decline in receptivity. However, reducing the magnitude of the assist operation amount in the first place leads to a decrease in the value and effect of driving assistance for the driver, and it is therefore desirable to suppress the decline in receptivity by taking measures against the fundamental cause of the decline in receptivity. Therefore, in this embodiment, for a driver who is driving safely but whose receptivity has decreased, the driving preferences and safe driving consciousness of the driver are learned, and the standard trajectory 55 itself is changed to match the driving characteristics of the driver.

[0114] 19 is a functional block diagram of a vehicle control device 2A according to the second embodiment. The vehicle control device 2A includes a driver operation amount acquisition unit 20, a vehicle state acquisition unit 21, an external environment data acquisition unit 22, a driver state acquisition unit 23, a surrounding risk determination unit 24, a norm calculation unit 25, an operation amount determination unit 26, a support acceptance determination unit 27, a driving behavior determination unit 28, and an operation amount change unit 29. The behaviors of the driver operation amount acquisition unit 20, the vehicle state acquisition unit 21, the external environment data acquisition unit 22, the driver state acquisition unit 23, the surrounding risk determination unit 24, the operation amount determination unit 26, the support acceptance determination unit 27, and the driving behavior determination unit 28 are the same as those in the second embodiment, and therefore description thereof will be omitted.

[0115] The norm calculation unit 25A calculates a target route and speed at which the host vehicle 1 should travel as a norm trajectory 55 based on the current position and travel angle of the host vehicle 1 acquired by the vehicle state acquisition unit 21, the external environment data (including road shape and traffic rules) acquired by the external environment data acquisition unit 22, and the risk area 54 acquired by the surrounding risk determination unit 24. The norm calculation unit 25A has multiple variables as norm trajectory generation parameters, such as the minimum distance between the risk area 54 and the norm trajectory 55, the steering start position when steering to avoid the risk area 54, and the passing speed in the vicinity of the risk area 54. Hereinafter, the minimum distance between the risk area 54 and the norm trajectory 55, which is included in the norm trajectory generation parameters, will also be referred to as a "second parameter."

[0116] The norm calculation unit 25A changes the parameters based on a request to change the parameters from the manipulated variable change unit 29, which will be described later, and changes the norm trajectory 55. The norm calculation unit 25A also stores past parameter setting values ​​for the driver, and when the driver state acquisition unit 23 recognizes that the driver will be driving again, calls up these parameter setting values ​​and reflects them in generating the norm trajectory 55.

[0117] When the acceptability quantitative value calculated by the assistance acceptance degree determination unit 27 is low, the operation amount change unit 29A changes the parameters to reduce the magnitude of the assist operation amount and leaves driving to the driver's own discretion. The parameters to be changed are the assist gain Ka in the operation amount determination unit 26 described in the first embodiment and the normative trajectory generation parameter stored in the norm calculation unit 25. Specifically, when the safe driving level of the driver calculated by the driving behavior determination unit 28 is high and the acceptability quantitative value is low, the operation amount change unit 29 performs the following process. First, the operation amount change unit 29 calculates the normative trajectory generation parameter so that the actual operation trajectory 56 of the driver is calculated as the normative trajectory 55. Then, the operation amount change unit 29 compares the calculated normative trajectory generation parameter with the normative trajectory generation parameter set in the norm calculation unit 25 and outputs a command to change the normative trajectory generation parameter to the norm calculation unit 25 so that the actual operation trajectory 56 approaches the calculated normative trajectory generation parameter.

[0118] The operation of the norm calculation unit 25A and the operation amount change unit 29A will be described with reference to Figures 20 and 21. In both Figures 20 and 21, a parked vehicle 52 is present on the front left side of the host vehicle 1, and the norm trajectory generation parameters obtained by the driving shown in Figure 20 are used in Figure 21. In both Figures 20 and 21, driver A is operating the host vehicle 1. Figures 20(a) to 20(d) correspond to Figures 21(a) to 21(d). Figure 20(a) shows the norm trajectory 55 and the actual operation trajectory 56, and Figures 20(b) to 20(d) show the time-series changes in the safe driving level 64, the acceptability quantitative value 59, and the assist gain Ka.

[0119] As shown in Fig. 20(a), driver A is driving at a position farther from parked vehicle 52 than standard trajectory 55, and as shown in Fig. 20(b), a safe driving level 64 is calculated to be high. Driver A is driving on actual operation trajectory 56 that does not match standard trajectory 55, and as shown in Fig. 20(c), driver A's acceptability quantitative value 59 is decreasing. After the time indicated by the two-dot chain line when driver A's acceptability quantitative value 59 falls below the acceptability threshold 68, the operation amount change unit 29 decreases assist gain 69 for driver A as shown in Fig. 20(d). This is because driver A's safe driving level 64 is sufficiently high, and by reducing the amount of assist support for driver A and leaving the driving judgment to driver A, a further decrease in acceptability is prevented.

[0120] 20 shows a state in which the degree of safe driving of driver A is high and the acceptability quantitative value is low. The operation amount change unit 29 calculates and records the second parameter P2 for driver A, i.e., the minimum distance between the risk area 54 and the standard trajectory 55, based on the actual operation trajectory 56 and the risk area 54 of driver A. However, the recorded second parameter P2 may be the actual operation trajectory 56 and the risk area 54 of driver A themselves, or may be an average value of the actual operation trajectory 56 of driver A, the risk area 54, and the existing second parameter.

[0121] In Figure 21, a new normative trajectory 55-2 is generated, which is a normative trajectory 55 created using the second parameter P2 obtained from the driving of driver A shown in Figure 20. In Figure 21, for comparison with Figure 20, the indicators shown in Figure 20 are named "Previous" and have the subnumber "-1" added to their symbols, and the new indicators in Figure 21 are named "New" and have the subnumber "-2" added to their symbols. For example, the previous normative trajectory 55-1 shown in Figure 21(a) is the same as the normative trajectory 55 in Figure 20(a). Since the second parameter P2 in Figure 21 is a larger value than in Figure 20, the new normative trajectory 55-2 is generated at a position farther from the risk area 54 than the previous normative trajectory 55-1.

[0122] Although driver A passes through the same actual operation trajectory 56 as in FIG. 20, the deviation between the new normative trajectory 55-2 and the actual operation trajectory 56 is smaller than in FIG. 20. Therefore, the new acceptance quantitative value 59-2 shown in FIG. 21(c) is increased compared to the previous acceptance quantitative value 59-1 shown in FIG. 20. This is the result of the new normative trajectory 55-2 approaching driver A's actual operation trajectory 56, in other words, the norm approaching the driver's driving preferences. The safe driving level 64 shown in FIG. 21(b) remains unchanged from FIG. 20, but the new acceptance quantitative value 59-2 shown in FIG. 21(c) does not fall below the acceptance threshold 68, and the new assist gain 69-2 shown in FIG. 21(d) maintains its original value without decreasing from the time indicated by the two-dot chain line. This is a different behavior from the previous assist gain 69-1 shown in FIG. 20.

[0123] In this way, when the driver's safe driving level is high and the acceptability quantitative value is low, the method of calculating the normative trajectory 55 is changed so as to match the driver's past driving behavior (actual operation trajectory), thereby suppressing a decrease in acceptability and eliminating the need to reduce the assist gain, which is an advantage of this embodiment. Note that, as can be seen from the fact that Fig. 21 shows a later time than Fig. 20, the change in the second parameter is reflected the next time the same use case occurs again or the next time the driver drives, and is changed at a longer time interval than the assist gain Ka.

[0124] The second embodiment described above provides the following advantageous effects: (13) When the acceptability quantitative value is equal to or less than a predetermined threshold and the safe driving level is greater than the predetermined threshold, the operation amount change unit 29 changes the second parameter used to calculate the normative driving operation amount, i.e., the minimum distance between the risk area 54 and the normative trajectory 55, based on the risk area and the driving operation amount. Therefore, by changing the normative trajectory itself to match the driving preferences of a safe driving driver, it is possible to suppress a state in which the expected trajectories of the system and the driver differ, which is one of the fundamental causes of reduced acceptability, thereby suppressing a decrease in acceptability and realizing vehicle control that always provides an ideal level of operation assistance.

[0125] (14) The second parameter is changed less frequently than the first parameter.

[0126] (Variation 6) In each of the first and second embodiments, a configuration has been described in which the assist gains and standard trajectory generation parameters for the driver in the past are stored and reflected the next time the driver drives. However, to realize this, a mechanism is required to identify the driver and reset each parameter when a different driver drives. In this case, when a new driver drives the vehicle, assist control is performed by applying statistically general parameters to the attributes of the driver. Alternatively, parameters with the largest safety margin that the system can imagine may be applied.

[0127] (Variation 7) In each of the first and second embodiments, the parameters may be stored in a storage area inside the vehicle control device 2 or in a storage unit in a separate device inside the vehicle 1 but outside the vehicle control device 2. Furthermore, the vehicle control device 2 may be equipped with a communication unit (not shown) for communication with the outside of the vehicle 1, and the parameters may be stored outside the vehicle 1, such as on a cloud server. In the case of a configuration in which the parameters are stored outside the vehicle, when the driver drives another vehicle, the stored parameters can be called up via communication, thereby enabling calculations to be performed using parameters that are suitable for the driver from the start when driving the vehicle. In this case, if the vehicle is a different model, parameters adjusted for differences between the models are applied.

[0128] This modification provides the following advantageous effects: (15) At least one of the first parameter and the second parameter is stored in an external storage device, so that the driver who has been driving vehicle 1 can use the same parameter when driving another vehicle.

[0129] (Variation 8) In the first and second embodiments, the parameters are automatically changed depending on the acceptability and safe driving tendency, but the driver operation amount obtaining unit 20 may be provided with a means for inputting the driver's preferences, and the driver may set and change the parameters at his or her own will. Furthermore, the system may be provided with a user interface for informing the driver of the necessity of parameter change by text on a display or by voice.

[0130] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0131] (Variation 9) In the first and second embodiments, the hardware configuration of the vehicle control device 2 is not particularly limited. The vehicle control device 2 may have the hardware configuration shown in FIG. 22 . The vehicle control device 2 is a so-called computer, and can also be called an arithmetic device or a computing unit. The vehicle control device 2 includes a CPU 41 which is a central processing unit, a ROM 42 which is a read-only storage device, a RAM 43 which is a readable and writable storage device, a storage unit 44 which is a non-volatile storage device, and a communication device 45 which realizes communication with the outside of the vehicle 1. The CPU 41 loads a program stored in the ROM 42 into the RAM 43 and executes it to perform the various calculations described above.

[0132] The vehicle control device 2 may be realized by a field programmable gate array (FPGA), which is a rewritable logic circuit, or an application specific integrated circuit (ASIC), which is an integrated circuit for a specific application, instead of the combination of the CPU 41, the ROM 42, and the RAM 43. Furthermore, the vehicle control device 2 may be realized by a combination of different configurations, for example, a combination of the CPU 41, the ROM 42, the RAM 43, and the FPGA, instead of the combination of the CPU 41, the ROM 42, and the RAM 43.

[0133] The vehicle control device 2 may further include a storage medium interface (hereinafter referred to as "storage medium IF") 49, and may read the program from a storage medium 99 and store it in the storage unit 44. Furthermore, the vehicle control device 2 may receive the program as a data signal via a carrier wave 98 using the communication device 45, and store the received program in the storage unit 44. In this case, the program stored in the storage unit 44 is used instead of the program stored in the ROM 42.

[0134] The above-described embodiments and modifications may be combined with each other. Although various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention.

[0135] 1: Vehicle (vehicle) 2, 2A: Vehicle control device 20: Driver operation amount acquisition unit 21: Vehicle state acquisition unit 22: External data acquisition unit 23: Driver state acquisition unit 24: Surrounding risk determination unit 25, 25A: Norm calculation unit 26: Operation amount determination unit 27: Assist acceptance determination unit 28: Driving behavior determination unit 29, 29A: Operation amount change unit 54: Risk area 55: Normative trajectory 56: Actual operation trajectory 57: Steering assist torque 59: Acceptability quantitative value 62: Driver gaze point 64: Safe driving level 65: Normative speed 66: Actual speed 68: Acceptability threshold 69: Assist gain Ka: Assist gain P2: Second parameter

Claims

1. A vehicle control device that can be installed in a vehicle driven by a driver, comprising: a surrounding risk determination unit that determines a risk area, which is a high-risk area around the vehicle, from external information; a norm calculation unit that calculates a standard driving operation amount based on at least the risk area; an operation amount determination unit that determines an assist operation amount based on a first parameter that determines the magnitude of an assist operation amount to assist the driver's driving operation, the standard driving operation amount, and the driver's driving operation amount; an assistance acceptance determination unit that calculates an acceptability quantitative value that indicates the driver's degree of acceptability to the assist operation amount based on at least one of the assist operation amount, the driving operation amount, and a driver state that represents the driver's state; an operation amount change unit that changes the first parameter so that the assist operation amount is smaller the lower the acceptability quantitative value; and a driving behavior determination unit that calculates a safe driving level, which is an index of the safety of the driver's driving operation of the vehicle, based on the driving operation amount and the risk area, and the operation amount change unit further changes the first parameter based on the safe driving level.

2. A vehicle control device according to claim 1, wherein the normative driving operation amount calculated by the norm calculation unit includes at least one of the vehicle's travel route, speed, steering amount, and acceleration / deceleration amount.

3. A vehicle control device as described in claim 1, wherein the norm calculation unit calculates the norm driving operation amount so that the distance to the risk area increases or the speed when passing near the risk area decreases.

4. A vehicle control device according to claim 1, wherein the operation amount determination unit determines the assist operation amount based on a deviation between the standard driving operation amount and the driving operation amount.

5. A vehicle control device according to claim 1 or claim 4, wherein the operation amount determination unit determines a proportional gain as the first parameter, and calculates at least one of a steering assist torque and an acceleration fluctuation value by multiplying the deviation between the reference driving operation amount and the driving operation amount by the proportional gain.

6. A vehicle control device according to claim 1, wherein the norm calculation unit calculates a plurality of the norm driving operation amounts or sets the norm driving operation amount having a range.

7. A vehicle control device according to claim 1 or claim 4, wherein the operation amount determination unit sets a dead zone for the deviation between the standard driving operation amount and the driving operation amount, and determines the assist operation amount.

8. A vehicle control device according to claim 1, wherein the assistance acceptance determination unit calculates the acceptance quantitative value based on a difference in sign between the assist operation amount and the driving operation amount.

9. A vehicle control device according to claim 1, wherein the assistance acceptance determination unit calculates the acceptance quantitative value based on the variance in the driving operation amount.

10. A vehicle control device according to claim 1, wherein the support acceptance determination unit acquires gaze data of the driver as the driver state, and determines the acceptance quantitative value based on the gaze data.

11. A vehicle control device as described in claim 1, wherein the driving behavior determination unit calculates the degree of safe driving based on at least one of the distance between the risk area and the vehicle and the speed of the vehicle when it passes near the risk area.

12. A vehicle control device as described in claim 1 or claim 11, wherein the operation amount change unit changes the first parameter when the safe driving level is greater than a predetermined threshold value so that the assist operation amount is smaller than when the safe driving level is equal to or less than the predetermined threshold value.

13. A vehicle control device as described in claim 1, wherein the operation amount change unit changes a second parameter used to calculate the standard driving operation amount based on the risk area and the driving operation amount when the acceptability quantitative value is equal to or less than a predetermined threshold and the safe driving level is greater than a predetermined threshold.

14. A vehicle control device according to claim 13, wherein the second parameter is changed less frequently than the first parameter.

15. A vehicle control device according to claim 13, wherein at least one of the first parameter and the second parameter is stored in an external storage device.

16. A vehicle control method executed by a vehicle control device that is a computer that can be installed in a vehicle driven by a driver, comprising: a surrounding risk determination process that determines a risk area, which is a high-risk area present around the vehicle, from external information; a norm calculation process that calculates a normative driving operation amount based on at least the risk area; an operation amount determination process that determines an assist operation amount based on a first parameter that determines the magnitude of an assist operation amount to assist the driver's driving operation, the normative driving operation amount, and the driver's driving operation amount; an assistance acceptance determination process that calculates an acceptability quantitative value indicating the driver's degree of acceptability to the assist operation amount based on at least one of the assist operation amount, the driving operation amount, and a driver state that represents the driver's state; an operation amount change process that changes the first parameter so that the assist operation amount is smaller the lower the acceptability quantitative value; and a driving behavior determination process that calculates a safe driving level, which is an index of safety of the driver's driving operation of the vehicle, based on the driving operation amount and the risk area, wherein the operation amount change process further changes the first parameter based on the safe driving level.

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