JP7803196B2 - Vehicle control method and vehicle control device - Google Patents

Description

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

Patent Document 1 describes a technology in a vehicle control system capable of rear-wheel steering that sets a target vehicle body slip angle using different vehicle body slip angle gains for manual driving and automatic driving, and limits the rate of change of the gain when switching between manual driving and automatic driving.

International Publication No. 2014/016947

The physical values that govern a vehicle's turning motion include the lateral force at the vehicle's center of gravity, the yaw moment around the center of gravity, the vehicle's yaw rate, and the vehicle's slip angle. Once the yaw rate and vehicle's slip angle are determined, the center of rotation of the yaw rotation when the vehicle turns (hereafter sometimes referred to as the "yaw center") is determined. In other words, once any two of the physical values of yaw rate, vehicle's slip angle, and yaw center are determined, the remaining physical value is determined.

Therefore, when control is performed to switch the target lateral force, target yaw moment, target yaw rate, and target vehicle body slip angle between manual driving and automatic driving, the yaw center may suddenly change due to changes in the target yaw rate and target vehicle body slip angle.
If the yaw center suddenly changes during a turn, the yaw rate pulsates, increasing or decreasing, and the resulting roll motion of the vehicle adds lateral acceleration that shakes the occupants, causing discomfort.
An object of the present invention is to suppress a sudden change in the center of rotation of yaw rotation during turning when switching the target lateral force, target yaw moment, target yaw rate, and target vehicle body slip angle between manual driving and automatic driving.

A vehicle control method according to one aspect of the present invention sets a target driving trajectory for a vehicle, calculates a first target lateral force, a first target yaw moment, a first target yaw rate, and a first target yaw rotation center point, which are target values for the lateral force, yaw moment, yaw rate, and yaw rotation center point in automatic driving control for driving the vehicle along the target driving trajectory, detects the steering angle of the steering wheel by the driver, and calculates a second target lateral force, a second target yaw moment, a second target yaw rate, and a second target yaw rotation center point, which are target values for the lateral force, yaw moment, yaw rate, and yaw rotation center point in manual driving based on the detected steering angle, and controls the automatic driving in accordance with the steering amount of the steering wheel by the driver. The system estimates the amount of override during turning, and calculates a third target lateral force by combining the first target lateral force and the second target lateral force, a third target yaw moment by combining the first target yaw moment and the second target yaw moment, a third target yaw rate by combining the first target yaw rate and the second target yaw rate, and a third target yaw rotation center point by combining the first target yaw rotation center point and the second target yaw rotation center point, using a mixing ratio corresponding to the estimated override amount. It then calculates target steering angles for the front and rear wheels that achieve the third target lateral force, third target yaw moment, third target yaw rate, and third target yaw rotation center point, and steers the front and rear wheels so that the steering angles of the front and rear wheels become the target steering angles.

This invention makes it possible to suppress sudden changes in the center of rotation of yaw rotation during turning when switching the target lateral force, target yaw moment, target yaw rate, and target vehicle slip angle between manual driving and automatic driving.

1 is a diagram illustrating an example of a schematic configuration of a vehicle equipped with a vehicle control device according to an embodiment; FIG. 2 is a block diagram illustrating an example of a functional configuration of the vehicle motion controller of FIG. 1 . FIG. 2 is an explanatory diagram of a load center of gravity position. 4 is an explanatory diagram of an example of a method for estimating the position of the center of gravity of a load in the front-rear direction of a vehicle. FIG. 3 is a flowchart illustrating an example of a vehicle control method according to an embodiment.

Embodiments of the present invention will be described below with reference to the drawings. Note that the drawings are schematic and may differ from the actual product. Furthermore, the embodiments of the present invention shown below are examples of devices and methods that embody the technical concept of the present invention, and the technical concept of the present invention does not limit the structure, arrangement, etc. of component parts to those described below. The technical concept of the present invention may be modified in various ways within the technical scope defined by the claims.

(composition)
1 is a diagram showing an example of a schematic configuration of a vehicle equipped with a vehicle control device according to an embodiment. The vehicle 1 is a four-wheel steering vehicle capable of steering each of its front wheels 2F (a left front wheel 2FL and a right front wheel 2FR) and rear wheels (a left rear wheel 2RL and a right rear wheel 2RR). The vehicle control device 10 controls the front wheel steering angle δF of the front wheels 2F and the rear wheel steering angle δR of the rear wheels 2R, as well as the driving force and braking force of the vehicle 1.
The vehicle 1 is a vehicle having a function of performing automatic driving control that automatically controls at least the steering angle among the steering angle, driving force, and braking force. The automatic driving control of the vehicle 1 may be autonomous driving control that automatically drives the vehicle 1 without the involvement of an occupant (e.g., a driver). The automatic driving control of the vehicle 1 may also be driving assistance control that assists the driver in driving the vehicle 1 by automatically controlling the steering angle among the steering angle, driving force, and braking force. For example, the driving assistance control includes lane keeping control, merging assistance control, and an automatic lane change function.

The vehicle control device 10 includes a positioning device 11, a map database (map DB) 12, an external sensor 13, a vehicle sensor 14, a vehicle motion controller 15, a drive source controller 16, a brake controller 17, a front wheel steering controller 18, a rear wheel steering controller 19, a driving control controller 20, a drive force source 21, a hydraulic actuator 22, a front wheel steering actuator 23, and a rear wheel steering actuator 24.
The positioning device 11 measures the current position of the vehicle 1. The positioning device 11 may include, for example, a Global Navigation System (GNSS) receiver. The GNSS receiver is, for example, a Global Positioning System (GPS) receiver, and receives radio waves from navigation satellites to measure the current position of the vehicle 1.

Map data is stored in map DB 12. The map data stored in map DB 12 may be high-precision map data suitable as map information for autonomous driving. High-precision map data is data with higher precision than map data for navigation, and includes information on a lane-by-lane basis. The map data stored in map DB 12 may also be map data for navigation. Map data for navigation includes information on a road-by-road basis.

The external sensor 13 detects various information (ambient environment information) about the environment around the vehicle 1. For example, the external sensor 13 detects objects around the vehicle 1. The external sensor 13 detects the environment around the vehicle 1, such as objects present around the vehicle 1, the relative position between the vehicle 1 and the objects, the distance between the vehicle 1 and the objects, and the direction in which the objects are present. The external sensor 13 outputs the detected information about the ambient environment to the driving controller 20 as ambient environment information.
The external sensor 13 may include a monocular camera such as a full HD color camera. The camera captures an image including a recognition target in the environment surrounding the vehicle 1 and outputs the captured image to the driving controller 20 as surrounding environment information. The external sensor 13 may also include a distance measuring device such as a laser range finder (LRF), radar, or LiDAR (Light Detection and Ranging) laser radar. The distance measuring device detects the relative position of the vehicle, which is determined by the relative distance and direction to an object present around the vehicle. The distance measuring device outputs the detected distance data to the driving controller 20 as surrounding environment information.

The vehicle sensors 14 detect various information (vehicle information) obtained from the vehicle 1. The vehicle sensors 14 include, for example, a vehicle speed sensor that detects the vehicle's traveling speed (vehicle speed) V, wheel speed sensors that detect the rotational speed of each tire equipped on the vehicle 1, a three-axis acceleration sensor (G sensor) that detects the acceleration (including deceleration) of the vehicle 1 in three axial directions, a steering angle sensor that detects the steering angle θs2 of the steering wheel, a gyro sensor that detects the angular velocity generated in the vehicle 1, a yaw rate sensor that detects the yaw rate, an accelerator sensor that detects the accelerator operation amount Ac2, which is the amount of operation of the accelerator pedal of the vehicle 1, and a brake sensor that detects the brake operation amount Br2, which is the amount of operation of the brake pedal by the driver. The vehicle sensors 14 output the detected vehicle information to the vehicle motion controller 15 and the driving control controller 20.

The vehicle motion controller 15 is an electronic control unit (ECU) that controls the front wheel steering angle δF, rear wheel steering angle δR, driving force, and braking force of the vehicle 1. The drive source controller 16 is an ECU that causes the drive power source 21 to generate a target drive torque Tdt instructed by a control signal output from the vehicle motion controller 15. The drive power source 21 may include, for example, one or both of a drive motor and an internal combustion engine (engine).

The brake controller 17 is an ECU that generates a target hydraulic pressure Pt indicated by a control signal output from the vehicle motion controller 15 in a hydraulic actuator 22 interposed between the master cylinder and the brake caliper of each wheel.
The front wheel steering controller 18 and the rear wheel steering controller 19 are ECUs that drive the front wheel steering actuator 23 and the rear wheel steering actuator 24 so that the steering angle δF of the front wheels 2F and the steering angle δR of the rear wheels become the target front wheel steering angle δFt and the target rear wheel steering angle δRt instructed by the control signals output from the vehicle motion controller 15.

The driving controller 20 is an ECU that executes the automatic driving control, which is the autonomous driving control or the driving assistance control.
For example, when autonomous driving control is performed, once a planned driving route from the current position to the destination is set by a navigation system or the like, the driving control controller 20 generates a target driving trajectory for the vehicle 1 to drive and a target vehicle speed profile for the vehicle 1 to drive along the target driving trajectory based on the map data stored in the map DB 12, the surrounding environment information output by the external sensor 13, and the vehicle information output by the vehicle sensor 14.

For example, when performing driving assistance control, the driving controller 20 generates a target driving trajectory for the vehicle 1 to travel based on the surrounding environment information output by the external sensor 13 and the vehicle information output by the vehicle sensor 14. When controlling driving force and braking force in driving assistance control, a target vehicle speed profile may be generated. For example, in merging assistance control and automated lane change functions, both a target driving trajectory and a target vehicle speed profile may be generated. In lane keeping control, a target driving trajectory may be generated.

The driving controller 20 calculates the steering angle θs1, accelerator operation amount Ac1, and brake operation amount Br1 that cause the vehicle 1 to travel in accordance with the target driving trajectory and/or target vehicle speed profile, and outputs these operation amounts to the vehicle motion controller 15.
When executing autonomous driving control, the driving controller 20 may calculate a target acceleration/deceleration ax instead of the accelerator operation amount Ac1 and the brake operation amount Br1 and output the calculated target acceleration/deceleration ax to the vehicle motion controller 15.
In addition, instead of the steering angle θs1, the driving control controller 20 may calculate turning target values such as a target lateral force, a target yaw moment, and a target yaw rate for the vehicle 1 to travel on the target traveling trajectory at a vehicle speed that conforms to the target vehicle speed profile, and output these to the vehicle motion controller 15.

The vehicle motion controller 15, drive source controller 16, brake controller 17, front wheel steering controller 18, rear wheel steering controller 19, and driving control controller 20 each include a processor 15a to 20a and peripheral components such as a memory device 15b to 20b.
The processors 15a to 20a may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit).
The storage devices 15b to 20b may include semiconductor storage devices, magnetic storage devices, optical storage devices, etc. The storage devices 15b to 20b may include memories such as registers, cache memories, and ROMs (Read Only Memory) and RAMs (Random Access Memory) used as main storage devices.

The functions of the vehicle motion controller 15, drive source controller 16, brake controller 17, front wheel steering controller 18, rear wheel steering controller 19, and driving control controller 20 described below are realized, for example, by processors 15a to 20a executing computer programs stored in storage devices 15b to 20b.
The vehicle motion controller 15, drive source controller 16, brake controller 17, front wheel steering controller 18, rear wheel steering controller 19, and drive control controller 20 may be formed by dedicated hardware for executing the information processing described below. For example, the vehicle motion controller 15, drive source controller 16, brake controller 17, front wheel steering controller 18, rear wheel steering controller 19, and drive control controller 20 may have a functional logic circuit (such as a programmable logic device (PLD) such as a field programmable gate array (FPGA)) set in a general-purpose semiconductor integrated circuit.

Next, a description will be given of control by the vehicle motion controller 15. In the autonomous driving control, the vehicle motion controller 15 calculates a first target lateral force Fyt1, a first target yaw moment Mzt1, a first target yaw rate γt1, and a first target vehicle body slip angle βt1, which are target values for the lateral force Fy at the center of gravity of the vehicle 1, the yaw rate Mz about the center of gravity, the yaw rate γ of the vehicle body, and the vehicle body slip angle β, based on the steering angle θs1 output by the driving controller 20.
The vehicle motion controller 15 controls the front wheel steering angle δF and the rear wheel steering angle δR to achieve the first target lateral force Fyt1, the first target yaw moment Mzt1, the first target yaw rate γt1, and the first target vehicle body slip angle βt1.

On the other hand, when the driver operates the steering wheel during manual driving or automatic driving control, the second target lateral force Fyt2, second target yaw moment Mzt2, second target yaw rate γt2, and second target vehicle body slip angle βt2 are calculated based on the steering angle θs2 detected by the steering angle sensor of the vehicle sensor 14. The vehicle motion controller 15 controls the front wheel steering angle δF and rear wheel steering angle δR to achieve the second target lateral force Fyt2, second target yaw moment Mzt2, second target yaw rate γt2, and second target vehicle body slip angle βt2.

When the driver operates the steering wheel during automatic driving control (i.e., when an override operation occurs), the vehicle motion controller 15 switches the target values of the lateral force Fy, yaw rate Mz, yaw rate γ, and vehicle body slip angle β from the first target lateral force Fyt1, first target yaw moment Mzt1, first target yaw rate γt1, and first target vehicle body slip angle βt1 to the second target lateral force Fyt2, second target yaw moment Mzt2, second target yaw rate γt2, and second target vehicle body slip angle βt2.
If the driver stops operating the steering wheel during automatic driving control (i.e., if the override operation is no longer performed), the vehicle motion controller 15 may switch the target values of the lateral force Fy, yaw rate Mz, yaw rate γ, and vehicle body slip angle β from the second target lateral force Fyt2, second target yaw moment Mzt2, second target yaw rate γt2, and second target vehicle body slip angle βt2 to the first target lateral force Fyt1, first target yaw moment Mzt1, first target yaw rate γt1, and first target vehicle body slip angle βt1.

As described above, once the yaw rate γ and vehicle body slip angle β are determined, the yaw center Pyc, which is the rotation center of the yaw rotation when the vehicle turns, is determined. Therefore, when the target value of the yaw rate γ switches between the first target yaw rate γt1 and the second target yaw rate γt2, and when the target value of the vehicle body slip angle β switches between the first target vehicle body slip angle βt1 and the second target vehicle body slip angle βt2, the yaw center Pyc of the vehicle 1 may suddenly change.
If the yaw center Pyc suddenly changes during a turn, the yaw rate γ pulsates to increase or decrease, and the resulting roll motion of the vehicle adds lateral acceleration that shakes the occupants, which can cause discomfort.

Therefore, the vehicle motion controller 15 estimates the override amount OR during automatic control in accordance with the steering amount of the steering wheel by the driver, and sets the blending ratio K in accordance with the estimated override amount OR.
Further, a first target yaw center Pyct1 is calculated based on the first target yaw rate γt1 and the first target vehicle body slip angle βt1, and a second target yaw center Pyct2 is calculated based on the second target yaw rate γt2 and the second target vehicle body slip angle βt2.

The vehicle motion controller 15 calculates the third target lateral force Fyt3 by blending the first target lateral force Fyt1 and the second target lateral force Fyt2 at a blending ratio K, calculates the third target yaw moment Mzt3 by blending the first target yaw moment Mzt1 and the second target yaw moment Mzt2 at a blending ratio K, calculates the third target yaw rate γt3 by blending the first target yaw rate γt1 and the second target yaw rate γt2 at a blending ratio K, and calculates the third target yaw center Pyct3 by blending the first target yaw center Pyct1 and the second target yaw center Pyct2 at a blending ratio K.

The vehicle motion controller 15 calculates a target front wheel steering angle δFt and a target rear wheel steering angle δRt that realize the third target lateral force Fyt3, the third target yaw moment Mzt3, the third target yaw rate γt3, and the third target yaw center Pyct3. The front wheel steering controller 18 and the rear wheel steering controller 19 steer the front wheels 2F and the rear wheel steering angle δR so that the front wheel steering angle δF and the rear wheel steering angle δR become the target steering angles δFt, δRt.
This allows the yaw center Pyc to be gradually changed based on the override amount OR corresponding to the steering amount of the steering wheel, thereby preventing a sudden change in the yaw center Pyc during cornering when switching the target lateral force, target yaw moment, target yaw rate, and target vehicle body slip angle between manual driving and automatic driving.

Figure 2 is a block diagram of an example of the functional configuration of the vehicle motion controller 15 of Figure 1. The vehicle motion controller 15 includes a target acceleration/deceleration calculation unit 30, a torque conversion unit 31, a hydraulic pressure conversion unit 32, a turning target value setting unit 33, yaw center calculation units 34 and 35, an override amount estimation unit 36, an arbitration unit 37, a limiter 38, a vehicle body slip angle calculation unit 39, and a steering angle calculation unit 40.

The target acceleration/deceleration calculation unit 30 calculates a target acceleration/deceleration ax to be generated in the vehicle 1. When the driving controller 20 calculates the accelerator operation amount Ac1 and the brake operation amount Br1 during automatic driving control, the target acceleration/deceleration calculation unit 30 calculates the target acceleration/deceleration ax based on the accelerator operation amount Ac1 and the brake operation amount Br1. During manual driving, the target acceleration/deceleration calculation unit 30 calculates the target acceleration/deceleration ax based on the accelerator operation amount Ac2 and the brake operation amount Br2 detected by the accelerator sensor and the brake sensor of the vehicle sensor 14.
If the driver operates the accelerator or brake during automatic driving control, the target acceleration/deceleration calculation unit 30 may, for example, select (select high) the larger of the accelerator operation amount Ac1 and the accelerator operation amount Ac2, or the larger of the brake operation amount Br1 and the brake operation amount Br2, and calculate the target acceleration/deceleration ax based on the selected operation amount.

The target acceleration/deceleration calculation unit 30 calculates a target driving force Fdt and a target braking force Fbt according to the target acceleration/deceleration ax. The target acceleration/deceleration calculation unit 30 outputs the target acceleration/deceleration ax to a turning target value setting unit 33, and outputs the target driving force Fdt and the target braking force Fbt to a torque conversion unit 31 and a hydraulic pressure conversion unit 32, respectively.
In addition, when the operation controller 20 directly calculates the target acceleration/deceleration ax, the target acceleration/deceleration ax output by the operation controller 20 may be used as the target acceleration/deceleration ax during automatic operation control.

The torque conversion unit 31 converts the target driving force Fdt calculated by the target acceleration/deceleration calculation unit 30 into a target driving torque Tdt, and outputs a control signal indicating the target driving torque Tdt to the driving source controller 16 .
The hydraulic pressure conversion unit 32 converts the target braking force Fbt calculated by the target acceleration/deceleration calculation unit 30 into a target hydraulic pressure Pt for the hydraulic actuator 22 and outputs a control signal indicative of the target hydraulic pressure Pt to the brake controller 17 .

The turning target value setting unit 33 sets the first target lateral force Fyt1, the first target yaw moment Mzt1, and the first target yaw rate γt1 based on the steering angle θs1 output by the driving controller 20 and the vehicle motion model. If the driving controller 20 directly calculates the target lateral force, the target yaw moment, and the target yaw rate, these values may be set as the first target lateral force Fyt1, the first target yaw moment Mzt1, and the first target yaw rate γt1. For example, the driving controller 20 may calculate the first target lateral force Fyt1 for driving the vehicle 1 on the target driving trajectory, and the turning target value setting unit 33 may set the first target yaw moment Mzt1 and the first target yaw rate γt1 based on the first target lateral force Fyt1.
In addition, the turning target value setting unit 33 sets a second target lateral force Fyt2, a second target yaw moment Mzt2, and a second target yaw rate γt2 based on the steering wheel steering angle θs1 detected by the vehicle sensor 14 and the vehicle motion model.

Furthermore, the turning target value setting unit 33 sets a second target vehicle body slip angle βt2, which is a target value of the vehicle body slip angle β when the driver is operating the steering wheel.
For example, the turning target value setting unit 33 may set the second target vehicle-body slip angle βt2 so that the yaw center Pyc of the turning vehicle 1 coincides with the center of gravity of the vehicle (i.e., the point of action of the resultant force of gravity acting on each part of the vehicle). Furthermore, for example, the turning target value setting unit 33 may set the second target vehicle-body slip angle βt2 so that the position of the yaw center Pyc in the vehicle's fore-and-aft direction coincides with the position in the vehicle's fore-and-aft direction of the point where the loads applied to the wheels 2F, 2R are balanced (i.e., the center of gravity of the total loads applied to the front wheels 2F and rear wheels 2R).
In the following description, the point at which the loads acting on the wheels are balanced may be referred to as the "load center of gravity position." Also, the center of gravity of the vehicle may be referred to as the "static center of gravity position."

The position of the center of gravity of the load will be explained with reference to Figure 3(a). The positions of the left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR are (x1, y1), (x2, y2), (x3, y3), and (x4, y4), respectively, and the loads acting on the left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR are L1, L2, L3, and L4, respectively.
The position (xG, yG) of the load center of gravity PLG, which is the center of gravity of the entire load applied to the wheels 2FL, 2FR, 2RL, and 2RR, can be defined by the following equations (1) and (2).
xG=(L1×x1+L2×x2+L3×x3+L4×x4)/(L1+L2+L3+L4)… (1)
yG=(L1×y1+L2×y2+L3×y3+L4×y4)/(L1+L2+L3+L4)… (2)

When the vehicle 1 is stationary or moving at a constant speed, the load center of gravity position PLG in the fore-and-aft direction of the vehicle approximately coincides with the static center of gravity position PG of the vehicle (i.e., the point of action of the resultant force of gravity acting on each part of the vehicle).
When the vehicle 1 is accelerating, the load center of gravity position PLG moves rearward from the static center of gravity position PG as shown in Fig. 3(b), and when the vehicle 1 is decelerating, the load center of gravity position PLG moves forward from the static center of gravity position PG as shown in Fig. 3(c).

The turning target value setting unit 33 calculates the movement amount lw of the load center of gravity position PLG in the vehicle longitudinal direction during acceleration/deceleration based on the target acceleration/deceleration ax, and sets it as the deviation lyc of the yaw center Pyc from the static center of gravity position PG.
4 is an explanatory diagram of an example of a method for estimating the position of the center of gravity of the load in the longitudinal direction of the vehicle, in which l is the wheelbase length, lR is the length from the static center of gravity position PG of the vehicle 1 to the rear wheel axle, and lF is the length from the static center of gravity position PG to the front wheel axle.
The turning target value setting unit 33 calculates the front wheel load Wf, which is the load applied to the front wheels 2F, and the rear wheel load Wr, which is the load applied to the rear wheels 2R, using the following equations (3) and (4).

In the above equations (3) and (4), m is the vehicle mass of the vehicle 1, g is the gravitational acceleration, and κ is a longitudinal load transfer coefficient determined in advance as a design value or an experimental value.

The turning target value setting unit 33 calculates a movement amount lw of the load center of gravity position PLG in the longitudinal direction of the vehicle from the ratio between the front wheel load Wf and the rear wheel load Wr. For example, the turning target value setting unit 33 may calculate the movement amount lw using the following equation (5). The sign of the movement amount lw is positive when the load center of gravity position PLG is forward of the static center of gravity position PG, and is negative when the load center of gravity position PLG is forward of the static center of gravity position PG.

The turning target value setting unit 33 sets the position of the yaw center Pyc to the post-movement load center of gravity position PLG. That is, the movement amount lw is set as the deviation lyc of the yaw center Pyc from the static center of gravity position PG.
The turning target value setting unit 33 calculates a second target vehicle body slip angle βt2 based on the deviation lyc, the second target yaw rate γt2, and the vehicle speed V using the following equation (6).

Furthermore, the turning target value setting unit 33 sets a first target vehicle body slip angle βt1, which is the target value of the vehicle body slip angle β in the automatic driving control.
The turning target value setting unit 33 may set the first target vehicle body slip angle βt1 so that the position of the yaw center Pyc coincides with the static center of gravity position PG or the load center of gravity position PLG, similar to the second target vehicle body slip angle βt2.

Furthermore, for example, the turning target value setting unit 33 may set a first target vehicle body slip angle βt1 that achieves the first target lateral force Fyt1, first target yaw moment Mzt1, and first target yaw rate γt1 at smaller target steering angles δFt, δRt. For example, the first target vehicle body slip angle βt1 that achieves the first target lateral force Fyt1, first target yaw moment Mzt1, and first target yaw rate γt1 may be set at the minimum target steering angles δFt, δRt. This reduces the drive amount of the front wheel steering actuator 23 and the rear wheel steering actuator 24, thereby reducing control delay.

Furthermore, for example, the turning target value setting unit 33 may set the first target vehicle-body slip angle βt1 in accordance with the turning radius so that the longitudinal direction of the vehicle 1 is directed toward the inside of the turning direction relative to the traveling direction of the vehicle 1 (i.e., the tangential direction of the turning trajectory). This makes it easier for the detection range of the camera and distance measuring device of the external sensor 13 to cover the area ahead of the turning path of the vehicle 1.
The turning target value setting unit 33 outputs the first target vehicle body slip angle βt1 and the second target vehicle body slip angle βt2 to the yaw center calculation units 34 and 35, respectively.

The yaw center calculation unit 34 calculates the deviation lyct1 of the first target yaw center Pyct1 in the vehicle longitudinal direction from the static center-of-gravity position PG. Specifically, the yaw center calculation unit 34 calculates the deviation lyct1 based on the first target yaw rate γt1, the first target vehicle body slip angle βt1, and the vehicle speed V using the following equation (7).
The yaw center calculation unit 35 calculates the deviation lyct2 of the second target yaw center Pyct2 in the vehicle longitudinal direction from the static center-of-gravity position PG. Specifically, the yaw center calculation unit 35 calculates the deviation lyct2 based on the second target yaw rate γt2, the second target vehicle-body slip angle βt2, and the vehicle speed V using the following equation (8).
The yaw center calculation units 34 and 35 output the deviations lyct1 and lyct2 to the arbitration unit 37.

The override amount estimating unit 36 estimates an override amount OR during automatic control in accordance with the amount of steering of the steering wheel by the driver based on the steering angle θs2. For example, the larger the steering angle θs2, the larger the estimated override amount OR.
The override amount estimation unit 36 sets a mixture ratio K according to the override amount OR and outputs it to the arbitration unit 37. The mixture ratio K is a coefficient between 0 and 1. For example, when the override amount OR is 0 (i.e., when the amount of steering of the steering wheel by the driver is 0), the mixture ratio K has a maximum value of "1," and as the override amount OR increases, the mixture ratio K decreases, and when the override amount OR reaches a predetermined value, the mixture ratio K reaches a minimum value of "0."

The arbitration unit 37 calculates the third target lateral force Fyt3 by blending the first target lateral force Fyt1 and the second target lateral force Fyt2 at a blending ratio K using the following equation (9).
Fyt3=K×Fyt1+(1-K)×Fyt2…(9)
The arbitration unit 37 calculates the third target yaw moment Mzt3 by blending the first target yaw moment Mzt1 and the second target yaw moment Mzt2 at a blending ratio K using the following equation (10).
Mzt3=K×Mzt1+(1-K)×Mzt2…(10)

The arbitration unit 37 calculates a third target yaw rate γt3 by blending the first target yaw rate γt1 and the second target yaw rate γt2 at a blending ratio K using the following equation (11).
γt3=K×γt1+(1−K)×γt2…(11)
The arbitration unit 37 calculates the deviation lyct3 by blending the deviation lyct1 and the deviation lyct2 at a blending ratio K using the following equation (12).
lyct3=K×lyct1+(1-K)×lyct2…(12)
The deviation lyct3 in equation (12) is equal to the deviation of the third target yaw center Pyct3, which is a combination of the first target yaw center Pyct1 and the second target yaw center Pyct2 at the combination ratio K, from the static center-of-gravity position PG.

The arbitration unit 37 outputs the third target lateral force Fyt3, the third target yaw moment Mzt3, and the third target yaw rate γt3 to the steering angle calculation unit 40. The arbitration unit 37 also outputs the deviation lyct3 to the limiter .
The limiter 38 limits the upper and lower limits of the deviation lyct3 to arbitrary set values lmax and lmin, respectively. It also limits the upper limit of the rate of increase and the lower limit of the rate of decrease of the deviation lyct3 to arbitrary set values Δlmax and Δlmin, respectively. The rate of decrease is a negative value, and the lower limit of the rate of decrease is the upper limit of the absolute value of the rate of decrease.
The vehicle body slip angle calculation unit 39 calculates a third target vehicle body slip angle βt3 based on the deviation lyct3 limited by the limiter 38, the third target yaw rate γt3, and the vehicle speed V, using the following equation (13).

The vehicle body slip angle calculation section 39 outputs the third target vehicle body slip angle βt3 to the steering angle calculation section 40.

The steering angle calculation unit 40 calculates the target wheel slip angle βFt for the front wheels 2F and the target wheel slip angle βRt for the rear wheels 2R based on the third target lateral force Fyt3 and the third target yaw moment Mzt3 using the following equations (14) and (15).

In the above equations (14) and (15), Cf is the cornering stiffness per front wheel 2F, and Cr is the cornering stiffness per rear wheel 2R.

The steering angle calculation unit 40 calculates the target front wheel steering angle δFt and the target rear wheel steering angle δRt based on the vehicle speed V, the third target yaw rate γt3, the third target vehicle body slip angle βt3, and the target wheel slip angles βFt, βRt using the following equations (16) and (17).

The steering angle calculation unit 40 outputs a control signal instructing the target front wheel steering angle δFt to the front wheel steering controller 18, and outputs a control signal instructing the target rear wheel steering angle δRt to the rear wheel steering controller 19.

(operation)
FIG. 5 is a flowchart of an example of a vehicle control method according to the embodiment.
In step S1, the driving controller 20 sets a target travel path along which the vehicle 1 is to travel.
In step S2, the steering angle sensor of the vehicle sensor 14 detects the steering angle θs2 of the steering wheel.
In step S3, the override amount estimating unit 36 estimates the override amount OR during automatic control in accordance with the amount of steering of the steering wheel by the driver. The override amount estimating unit 36 sets the blending ratio K in accordance with the override amount OR.

In step S4, the turning target value setting unit 33 sets a first target lateral force Fyt1, a first target yaw moment Mzt1, a first target yaw rate γt1, and a first target vehicle body slip angle βt1 for the automatic driving control.
In step S5, the yaw center calculation unit 34 calculates the deviation lyct1 of the first target yaw center Pyct1 in the longitudinal direction of the vehicle from the static center-of-gravity position PG.
In step S6, the turning target value setting unit 33 sets a second target lateral force Fyt2, a second target yaw moment Mzt2, a second target yaw rate γt2, and a second target vehicle body slip angle βt2 for manual driving.
In step S7, the yaw center calculation unit 35 calculates the deviation lyct2 of the second target yaw center Pyct2 in the longitudinal direction of the vehicle from the static center-of-gravity position PG.

In step S8, the arbitration unit 37 calculates the third target lateral force Fyt3 by blending the first target lateral force Fyt1 and the second target lateral force Fyt2 at the blending ratio K, calculates the third target yaw moment Mzt3 by blending the first target yaw moment Mzt1 and the second target yaw moment Mzt2 at the blending ratio K, calculates the third target yaw rate γt3 by blending the first target yaw rate γt1 and the second target yaw rate γt2 at the blending ratio K, and calculates the third target yaw center Pyct3 by blending the first target yaw center Pyct1 and the second target yaw center Pyct2 at the blending ratio K.

In step S9, the limiter 38 and the vehicle body slip angle calculation unit 39 calculate a third target vehicle body slip angle βt3.
In step S10, the steering angle calculation unit 40 calculates the target front wheel steering angle δFt and the target rear wheel steering angle δRt.
In step S11, the front wheel steering controller 18 and the rear wheel steering controller 19 steer the front wheels 2F and the rear wheels 2R so that the front wheel steering angle δF and the rear wheel steering angle δR become the target steering angles δFt and δRt. Then, the process ends.

(Effects of the embodiment)
(1) The steering angle sensor of the vehicle sensor 14 detects the steering angle of the steering wheel by the driver. The driving controller 20 sets a target driving trajectory of the vehicle 1.
The vehicle motion controller 15 calculates a first target lateral force, a first target yaw moment, a first target yaw rate, and a first target yaw rotation center point, which are target values of the lateral force, yaw moment, yaw rate, and yaw rotation center point in automatic driving control for driving the vehicle 1 along a target driving trajectory, and calculates a second target lateral force, a second target yaw moment, a second target yaw rate, and a second target yaw rotation center point, which are target values of the lateral force, yaw moment, yaw rate, and yaw rotation center point in manual driving based on the steering angle detected by the steering angle sensor, and calculates target values of the lateral force, yaw moment, yaw rate, and yaw rotation center point in automatic driving based on the steering amount of the steering wheel by the driver. and then calculates a third target lateral force by combining the first target lateral force and the second target lateral force, a third target yaw moment by combining the first target yaw moment and the second target yaw moment, a third target yaw rate by combining the first target yaw rate and the second target yaw rate, and a third target yaw rotation center point by combining the first target yaw rotation center point and the second target yaw rotation center point, all at a mixing ratio according to the estimated override amount, and then calculates target steering angles for the front wheels 2F and the rear wheels 2R that will realize the third target lateral force, the third target yaw moment, the third target yaw rate, and the third target yaw rotation center point.

The front wheel steering controller 18 and the rear wheel steering controller 19 steer the front wheels 2F and the rear wheels 2R so that the steering angles of the front wheels 2F and the rear wheels 2R become the target steering angles.
This allows the center of yaw rotation of the vehicle to be gradually changed based on the override amount corresponding to the steering amount of the steering wheel, thereby preventing a sudden change in the center of yaw rotation during a turn when switching the target lateral force, target yaw moment, target yaw rate, and target vehicle body slip angle between manual driving and automatic driving.

(2) The vehicle motion controller 15 may set a first target vehicle body slip angle, which is a target value of the vehicle body slip angle under automatic driving control, and may calculate a second target vehicle body slip angle, which is a target value of the vehicle body slip angle under manual driving, based on the detected steering angle. The vehicle motion controller 15 may calculate a first target yaw rotation center point based on the first target yaw rate and the first target vehicle body slip angle, and may calculate a second target yaw rotation center point based on the second target yaw rate and the second target vehicle body slip angle.
This makes it possible to calculate a third target yaw rotation center point that combines the first target yaw rotation center point under automatic driving control and the second target yaw rotation center point under manual driving at a mixing ratio that corresponds to the estimated override amount.

(3) The vehicle motion controller 15 may calculate a third target vehicle body slip angle based on the third target yaw rate and the third target yaw rotation center point, and may calculate a target steering angle based on the third target lateral force, the third target yaw moment, the third target yaw rate, and the third target vehicle body slip angle.
This makes it possible to calculate the target steering angle that realizes the third target yaw rotation center point.

1...vehicle, 2F...front wheels, 2R...rear wheels, 10...vehicle control device, 11...positioning device, 10...vehicle control device, 11...positioning device, 12...map database, 13...external sensor, 14...vehicle sensor, 15...vehicle motion controller, 16...drive source controller, 17...brake controller, 18...front wheel steering controller, 19...rear wheel steering controller, 20...driving control controller, 21...drive source, 22...hydraulic actuator, 23...front wheel steering actuator, 24...rear wheel steering actuator, 30...target acceleration/deceleration calculation unit, 31...torque conversion unit, 32...hydraulic pressure conversion unit, 33...turning target value setting unit, 34, 35...yaw center calculation unit, 36...override amount estimation unit, 37...mediation unit, 38...limiter, 39...vehicle body slip angle calculation unit, 40...steering angle calculation unit

Claims (4)

Setting a target driving trajectory for the vehicle;
calculating a first target lateral force, a first target yaw moment, a first target yaw rate, and a first target yaw rotation center point, which are target values of the lateral force, yaw moment, yaw rate, and yaw rotation center point in automatic driving control for driving the vehicle along the target driving trajectory;
Detects the steering angle of the steering wheel by the driver,
calculating a second target lateral force, a second target yaw moment, a second target yaw rate, and a second target yaw rotation center point, which are target values of the lateral force, yaw moment, yaw rate, and yaw rotation center point due to manual driving, based on the detected steering angle;
estimating an override amount during automatic driving in accordance with a steering angle of the steering wheel steered by the driver during automatic driving;
calculating a third target lateral force by combining the first target lateral force and the second target lateral force, a third target yaw moment by combining the first target yaw moment and the second target yaw moment, a third target yaw rate by combining the first target yaw rate and the second target yaw rate, and a third target yaw rotation center point by combining the first target yaw rotation center point and the second target yaw rotation center point, all at a combination ratio corresponding to the estimated override amount;
calculating target steering angles of the front wheels and the rear wheels that realize the third target lateral force, the third target yaw moment, the third target yaw rate, and the third target yaw rotation center point;
steer the front wheels and the rear wheels so that the steering angles of the front wheels and the rear wheels become the target steering angles;
A vehicle control method comprising: setting a first target vehicle body slip angle, which is a target value of the vehicle body slip angle in the automatic driving control;
calculating a second target vehicle body slip angle, which is a target value of the vehicle body slip angle during manual driving, in accordance with the detected steering angle;
calculating the first target yaw rotation center point based on the first target yaw rate and the first target vehicle body slip angle;
calculating the second target yaw rotation center point based on the second target yaw rate and the second target vehicle body slip angle;
2. The vehicle control method according to claim 1. calculating a third target vehicle body slip angle based on the third target yaw rate and the third target yaw rotation center point;
calculating the target steering angle based on the third target lateral force, the third target yaw moment, the third target yaw rate, and the third target vehicle body slip angle;
3. The vehicle control method according to claim 1 or 2. a steering angle sensor that detects the steering angle of a steering wheel by a driver;
a first target lateral force, a first target yaw moment, a first target yaw rate, and a first target yaw rotation center point, which are target values of the lateral force, yaw moment, yaw rate, and yaw rotation center point in automatic driving control that sets a target driving trajectory for the vehicle and drives the vehicle along the target driving trajectory; a second target lateral force, a second target yaw moment, a second target yaw rate, and a second target yaw rotation center point, which are target values of the lateral force, yaw moment, yaw rate, and yaw rotation center point in manual driving, based on the steering angle detected by the steering angle sensor; and a second target lateral force, a second target yaw moment, a second target yaw rate, and a second target yaw rotation center point in automatic driving that are target values of the lateral force, yaw moment, yaw rate, and yaw rotation center point in manual driving, based on the steering angle detected by the steering angle sensor; a controller that estimates an override amount, and calculates a third target lateral force by combining the first target lateral force and the second target lateral force, a third target yaw moment by combining the first target yaw moment and the second target yaw moment, a third target yaw rate by combining the first target yaw rate and the second target yaw rate, and a third target yaw rotation center point by combining the first target yaw rotation center point and the second target yaw rotation center point at a mixing ratio corresponding to the estimated override amount, and calculates target steering angles of the front wheels and the rear wheels that realize the third target lateral force, the third target yaw moment, the third target yaw rate, and the third target yaw rotation center point;
a steering actuator that steers the front wheels and the rear wheels so that the steering angles of the front wheels and the rear wheels become the target steering angles;
A vehicle control device comprising: