JP2023177030A - Travel control method and travel control device - Google Patents

Abstract

To reduce an occupant's feeling of strangeness that is caused due to a difference between a deceleration feeling that the occupant feels and deceleration that actually occurs in an own vehicle, when the own vehicle turns in accordance with a shape of a lane.SOLUTION: A travelling control method comprises a step (S2) of obtaining information on a shape of a lane on which an own vehicle travels; a step (S3) of calculating estimated lateral acceleration which is an estimated value of lateral acceleration that occurs in the own vehicle, on the basis of a detected value of a vehicle speed of the own vehicle or a target value and the shape of the lane; and steps (S4-S6) of controlling an attitude of the own vehicle when decelerating the own vehicle so that a downward pitch angle of the own vehicle becomes larger when the estimated lateral acceleration is large compared to when the acceleration is small.SELECTED DRAWING: Figure 6

Description

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

Patent Document 1 discloses that information about a curved road in front of the vehicle is acquired, the section distance from the vehicle to the entrance position of the curved road is calculated, and the shorter the section distance, the greater the deceleration of the vehicle during deceleration control. , a deceleration support device that calculates a target deceleration during deceleration control has been proposed.

Japanese Patent Application Publication No. 2010-76550

When the own vehicle turns according to the lane shape, the occupant of the own vehicle expects that the own vehicle will appropriately decelerate depending on the speed and speed of the turn. For example, when the vehicle makes a sharp turn, it is expected that the vehicle will decelerate more strongly. Therefore, if there is a difference between the feeling of deceleration felt by the occupant and the deceleration actually occurring in the vehicle, the occupant may feel uncomfortable.
The present invention aims to reduce the sense of discomfort caused by an occupant due to a difference between the feeling of deceleration that the occupant feels and the deceleration that actually occurs in the own vehicle when the own vehicle turns according to the lane shape. purpose.

In the driving control method according to one aspect of the present invention, information on the shape of the lane in which the host vehicle travels is acquired, and lateral lateral movement occurs in the host vehicle based on the detected value or target value of the vehicle speed of the host vehicle and the lane shape. The estimated lateral acceleration, which is an estimated value of acceleration, is calculated, and the attitude of the own vehicle when decelerating is adjusted so that the downward pitch angle of the own vehicle becomes larger when the estimated lateral acceleration is large than when it is small. Control.

According to the present invention, when the vehicle turns according to the lane shape, it is possible to reduce the discomfort felt by the passenger due to the difference between the feeling of deceleration that the passenger feels and the deceleration that actually occurs in the vehicle. .

FIG. 1 is a schematic configuration diagram of an example of a travel control device according to an embodiment. (a) to (d) are explanatory diagrams of an example of the travel control method according to the embodiment. FIG. 2 is a block diagram of an example of a functional configuration of a controller. (a) is a schematic diagram showing an example of a target pitch angle characteristic map with respect to estimated lateral acceleration, and (b) is a schematic diagram showing an example of a braking force distribution ratio characteristic map with respect to the target pitch angle. (a) is a schematic diagram of an example of a situation in which the vehicle is traveling on a lane with a curve in front, and (b) to (f) are vehicle speed, lateral acceleration, braking deceleration, estimated lateral acceleration, and pitch angle, respectively. This is a time chart. It is a flow chart of an example of a traveling control method of an embodiment.

Embodiments of the present invention will be described below with reference to the drawings. Note that each drawing is schematic and may differ from the actual drawing. In addition, the embodiments of the present invention shown below illustrate devices and methods for embodying the technical idea of the present invention. is not limited to the following: The technical idea of the present invention can be modified in various ways within the technical scope defined by the claims.

(composition)
FIG. 1 is a schematic configuration diagram of an example of a travel control device according to an embodiment. The driving control device 10 is mounted on the own vehicle 1 and executes driving control of the own vehicle 1.
The travel control device 10 includes an object sensor 11, a vehicle sensor 12, a positioning device 13, a map database 14, a communication device 15, a navigation device 16, a controller 17, a driving force source controller 18a, and a brake controller 18b. , a steering controller 18c, a driving force source 19a, a brake actuator 19b, and a steering actuator 19c. In the drawings, the map database is referred to as a "map DB" and the navigation device is referred to as a "navigation device."

The object sensor 11 detects various information about the environment around the own vehicle 1 (surrounding environment information). The object sensor 11 includes a plurality of sensors that detect objects around the vehicle 1, such as a laser radar mounted on the vehicle 1, a millimeter wave radar, a camera, and a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging). Equipped with different types of object detection sensors.
The vehicle sensor 12 is mounted on the own vehicle 1 and detects various information (vehicle information) obtained from the own vehicle 1. The vehicle sensors 12 include, for example, a vehicle speed sensor that detects the vehicle speed of the own vehicle 1, a wheel speed sensor that detects the rotational speed of the tires of the own vehicle 1, and a wheel speed sensor 3 that detects the acceleration and deceleration of the own vehicle 1 in three axial directions. Axial acceleration sensor, steering angle sensor that detects the steering angle of the steering wheel, steering angle sensor that detects the turning angle of the steered wheels (steered wheels), gyro sensor that detects the angular velocity of the own vehicle 1, and detects the yaw rate. It includes a yaw rate sensor, an accelerator sensor that detects the accelerator opening of the own vehicle, and a brake sensor that detects the amount of brake operation.

The positioning device 13 includes a global positioning system (GNSS) receiver, and measures the current position and orientation of the host vehicle 1 by receiving radio waves from a plurality of navigation satellites. The GNSS receiver may be, for example, a Global Positioning System (GPS) receiver. The positioning device 13 may be, for example, an inertial navigation device.
The map database 14 stores road map data. For example, the map database 14 may store high-precision map data (hereinafter simply referred to as "high-precision map") suitable as map information for automatic driving. The map database 14 may store map data for navigation (hereinafter simply referred to as "navigation map").
The communication device 15 performs wireless communication with a communication device external to the vehicle 1 . The communication method by the communication device 15 may be, for example, wireless communication using a public mobile telephone network, vehicle-to-vehicle communication, road-to-vehicle communication, or satellite communication.

The navigation device 16 recognizes the current position of the own vehicle using the positioning device 13 and acquires map information at the current position from the map database 14 . The navigation device 16 sets a target travel route to a destination input by the passenger, and provides route guidance to the passenger according to the target travel route. Additionally, the navigation device 16 outputs information on the target travel route to the controller 17. During autonomous driving control, the controller 17 automatically drives the own vehicle 1 so as to travel along the target travel route set by the navigation device 16.

The controller 17 is an electronic control unit (ECU) that controls the running of the host vehicle 1 .
For example, travel control by the controller 17 is set based on surrounding environment information from the object sensor 11, vehicle information from the vehicle sensor 12, current position measured by the positioning device 13, road map data, target travel route, etc. It may be an autonomous driving control that causes the own vehicle 1 to travel autonomously to a destination.
Further, for example, the driving control by the driving control device 10 is such that the driver drives the own vehicle 1 by controlling acceleration, deceleration, and steering of the own vehicle 1 based on surrounding environment information, vehicle information, road map data, etc. It may also be driving support control that supports.

For example, the driving support control includes lane maintenance control that controls the steering of the own vehicle 1 so that the own vehicle 1 does not deviate from the driving lane, and acceleration and control of the own vehicle 1 so that the own vehicle 1 follows the vehicle in front. It may include preceding vehicle following control that controls deceleration, constant speed driving control, and inter-vehicle distance control.
In the following description, an example will be described in which the travel control by the travel control device 10 is an autonomous driving control that causes the host vehicle 1 to travel autonomously to a set destination.

The controller 17 includes a processor 17a and peripheral components such as a storage device 17b. The processor 17a may be, for example, a CPU or an MPU. The storage device 17b may include a semiconductor storage device, a magnetic storage device, an optical storage device, or the like. The storage device 17b may include registers, cache memory, and memories such as ROM and RAM used as main storage devices. The functions of the controller 17 described below are realized, for example, by the processor 17a executing a computer program stored in the storage device 17b.
Note that the controller 17 may be formed of dedicated hardware for executing each information process described below. For example, the controller 17 may include a functional logic circuit set in a general-purpose semiconductor integrated circuit. For example, the controller 17 may include a PLD such as an FPGA.

The driving force source controller 18a is an ECU that causes the driving force source 19a to generate a target driving torque instructed by a control signal output from the controller 17. The driving force source 19a may include, for example, one or both of a driving motor and an internal combustion engine.
The brake controller 18b brakes the front wheels and the rear wheels of the own vehicle 1 so that the front wheels and the rear wheels of the own vehicle 1 generate the target front wheel braking force and the target rear wheel braking force instructed by the control signal output from the controller 17, respectively. This is an ECU that drives a brake actuator (hydraulic actuator) 19b that operates a device (brake device).
The steering controller 18c is an ECU that drives the steering actuator 19c so that the steering angle of the steered wheels (steered wheels) of the own vehicle becomes the target steering angle instructed by the control signal output from the controller 17. be.

Next, driving control by the controller 17 will be explained. FIGS. 2(a) to 2(d) are explanatory diagrams of an example of the travel control method according to the embodiment.
Now, as shown in Fig. 2(a), own vehicle 1 is traveling in lane TL (hereinafter sometimes referred to as "own lane TL"), and in front of the course of own vehicle 1, own lane TL is Assume a situation where the curve is steep. Reference symbols B1 and B2 indicate lane boundary lines on the left and right sides of the own lane TL, respectively.

When the own vehicle 1 turns according to the shape of the own lane TL under autonomous driving control, the occupants of the own vehicle 1 including the driver expect that the own vehicle 1 will appropriately decelerate depending on the speed and speed of the turn.
For example, if there is a relatively steep curve in front of the host vehicle 1 as shown in FIG. 2(a), it is expected that the host vehicle 1 will be controlled to decelerate at a strong deceleration. Therefore, even if the deceleration of the host vehicle 1 due to the autonomous driving control is actually appropriate, if the sense of deceleration felt by the occupant is insufficient, there is a risk that the occupant will feel uncomfortable (feeling uneasy).

FIG. 2(c) shows a situation where the own lane TL has a relatively gentle curve ahead of the own vehicle 1. If there is a relatively slow curve in front of the vehicle 1, the occupant expects that the vehicle 1 will be controlled to decelerate at a weak rate. Therefore, even if the deceleration of the own vehicle 1 due to autonomous driving control is actually appropriate, if the sense of deceleration felt by the occupant is excessive, there is a risk that the occupant will feel uncomfortable (for example, the ride is uncomfortable). There is.
Even when the vehicle 1 is being manually driven by the driver, there is a possibility that other occupants other than the driver (for example, a passenger in the front passenger seat) may feel a similar sense of discomfort.

Therefore, the controller 17 calculates an estimated lateral acceleration that is an estimated value of the lateral acceleration that will occur in the host vehicle in the future. For example, when the host vehicle 1 is being manually driven by the driver, the estimated lateral acceleration may be calculated based on the current vehicle speed of the host vehicle 1 and the lane shape of the host lane TL. Further, for example, when the own vehicle 1 is traveling automatically by autonomous driving control, the vehicle speed target value of the own vehicle 1 (for example, vehicle speed plan) and the target traveling trajectory generated from the lane shape of the own lane TL are The estimated lateral acceleration may be calculated based on this.

Then, the attitude of the own vehicle 1 when decelerating the own vehicle 1 is controlled so that when the estimated lateral acceleration is large than when the estimated lateral acceleration is small, the pitch angle in which the front end of the vehicle body is lowered becomes larger.
The solid lines in FIGS. 2(b) and 2(d) schematically show the pitch angle of the own vehicle 1 when the attitude of the own vehicle 1 is controlled based on the estimated lateral acceleration. For comparison, the broken line schematically shows the pitch angle when attitude control based on estimated lateral acceleration is not performed.

For example, when the estimated lateral acceleration becomes relatively large, the attitude of the host vehicle 1 is controlled so that the pitch angle in the direction of lowering the front end of the vehicle body becomes large, as shown by the solid line in FIG. 2(b).
As a result, when there is a relatively steep curve in front of the own vehicle 1, it is possible to give the occupants of the own vehicle 1 a greater sense of deceleration than the deceleration actually occurring in the own vehicle 1. As a result, it is possible to reduce the discomfort (feeling of anxiety) caused by the difference between the feeling of deceleration felt by the occupant and the deceleration actually occurring in the own vehicle.

On the other hand, when the estimated lateral acceleration becomes relatively small, the attitude of the own vehicle 1 is controlled so that the pitch angle in the direction of lowering the front end of the vehicle body becomes small, as shown by the solid line in FIG. 2(d).
As a result, when there is a relatively slow curve in front of the own vehicle 1, it is possible to give the occupants of the own vehicle 1 a feeling of deceleration smaller than the deceleration actually occurring in the own vehicle 1. As a result, it is possible to reduce the feeling of discomfort (for example, "uncomfortable ride") caused by the difference between the feeling of deceleration felt by the occupant and the deceleration actually occurring in the own vehicle.
By estimating the lateral acceleration generated in the own vehicle 1 in this way and changing the pitch angle of the own vehicle 1 according to the estimated lateral acceleration, the braking feeling given to the occupants is changed, and the The occupant can experience a sense of deceleration that matches the driving scene of the vehicle 1.

The functions of the controller 17 will be explained in detail with reference to FIG. The controller 17 includes a vehicle information acquisition section 30, a lane boundary acquisition section 31, an automatic driving control section 32, an estimated lateral acceleration calculation section 33, and a braking force distribution setting section 34.
The vehicle information acquisition unit 30 acquires vehicle information from the vehicle sensor 12. Among the vehicle information acquired from the vehicle sensor 12, the vehicle information acquisition section 30 outputs information on the current vehicle speed Vh of the host vehicle 1 to the estimated lateral acceleration calculation section 33. When the vehicle sensor 12 includes an acceleration sensor, information on acceleration (deceleration) in the longitudinal direction of the host vehicle 1 may be output to the estimated lateral acceleration calculation unit 33.
Further, the vehicle information acquisition section 30 outputs information on the amount of brake operation by the driver among the vehicle information acquired from the vehicle sensor 12 to the braking force distribution setting section 34 .

The lane boundary acquisition unit 31 acquires information on the position and shape of lane boundary lines B1 and B2 of the own lane TL in front of the own vehicle 1 (hereinafter sometimes referred to as "lane boundary information"), and performs automatic driving control. It outputs to the section 32 and the estimated lateral acceleration calculation section 33.
For example, the lane boundary acquisition unit 31 may acquire lane boundary information based on surrounding environment information output from the object sensor 11. For example, the positions and shapes of the lane boundary lines B1 and B2 may be recognized from the captured image of the area in front of the own vehicle 1 taken by the camera of the object sensor 11.
For example, the lane boundary acquisition unit 31 may acquire lane boundary information from a high-precision map stored in the map database 14 based on the current position and direction of the own vehicle measured by the positioning device 13.

The automatic driving control unit 32 automatically controls the own vehicle 1 by autonomous driving control based on the lane boundary information acquired by the lane boundary acquisition unit 31, the current position and direction of the own vehicle 1, and the target travel route to the destination. Generate a target travel trajectory for the vehicle to travel on. In addition, a vehicle speed plan (hereinafter sometimes referred to as a "target vehicle speed profile") is set, which is a target value of the vehicle speed of the host vehicle 1 at each point on the target travel trajectory.
The automatic driving control unit 32 includes a target trajectory generation unit 32a that generates a target travel trajectory and a target vehicle speed setting unit 32b that sets a target vehicle speed profile.

For example, the target trajectory generation unit 32a generates a route space map that expresses the route around the own vehicle 1 and the presence or absence of objects, and a risk map that quantifies the degree of danger of the driving field, and generates a motion characteristic of the own vehicle 1, The target travel trajectory may be generated based on the route space map and the risk map.
The target vehicle speed setting unit 32b sets the target vehicle speed based on the motion characteristics of the own vehicle 1, the upper limit speed (for example, the speed limit, legal speed, a set speed preset by the occupant of the own vehicle 1, the speed of the preceding vehicle), etc. Set up your profile.
The target trajectory generation section 32a outputs the target traveling trajectory and the target vehicle speed profile to the estimated lateral acceleration calculation section 33, and outputs the target vehicle speed profile to the braking force distribution setting section 34.

Estimated lateral acceleration calculating section 33 calculates estimated lateral acceleration, which is an estimated value of lateral acceleration (turning acceleration) that will occur in host vehicle 1 in the future. For example, the estimated lateral acceleration calculation unit 33 calculates the estimated lateral acceleration at a time in the future for a predetermined foreseeable time (for example, 3 seconds).
When the own vehicle 1 is automatically traveling under autonomous driving control, for example, the estimated lateral acceleration calculation unit 33 calculates the current state of the own vehicle 1 at a future time that is ahead by a forecast time based on the target traveling trajectory and the target vehicle speed profile. The turning curvature and target vehicle speed may be estimated, and the estimated lateral acceleration may be calculated based on the estimated turning curvature and target vehicle speed.

When the own vehicle 1 is being manually driven by the driver, the estimated lateral acceleration calculation unit 33 may predict the future speed of the own vehicle 1 based on the current speed and acceleration/deceleration of the own vehicle 1, for example. . The acceleration/deceleration may be obtained by differentiating the vehicle speed of the host vehicle 1, or information on the acceleration/deceleration may be obtained from an acceleration sensor.
The estimated lateral acceleration calculation unit 33 assumes that the own vehicle 1 runs in the center of the left and right lane boundaries B1 and B2, and calculates the estimated lateral acceleration at a future time that is ahead by a forecast time based on the predicted future vehicle speed of the own vehicle 1. The position of the host vehicle 1 may be estimated, and the turning curvature and vehicle speed at that time may be estimated. The estimated lateral acceleration calculation unit 33 may calculate the estimated lateral acceleration based on the estimated turning curvature and vehicle speed.
The estimated lateral acceleration calculating section 33 outputs the estimated lateral acceleration to the braking force distribution setting section 34.

The braking force distribution setting unit 34 distributes the braking force between the front wheels and the rear wheels according to the estimated lateral acceleration calculated by the estimated lateral acceleration calculation unit 33 when operating the braking device (braking device) to decelerate the own vehicle 1. By changing the ratio, the stroke amount of the front wheel and rear wheel suspension of the host vehicle 1 is changed to control the pitch angle (rotation angle with the vehicle width direction as the rotation axis) of the host vehicle 1.
The braking force distribution setting unit 34 sets the overall braking deceleration to be generated in the own vehicle 1 when decelerating the own vehicle 1. In the following description, the overall braking deceleration generated in the own vehicle 1 when decelerating the own vehicle 1 may be referred to as "required deceleration."

When the host vehicle 1 is automatically traveling under autonomous driving control, the braking force distribution setting unit 34 sets the required deceleration based on the target vehicle speed profile. When the host vehicle 1 is being driven manually by the driver, the required deceleration is set based on the amount of brake operation detected by the vehicle sensor 12.
The braking force distribution setting unit 34 calculates the sum of the braking forces to be generated at the front wheels and rear wheels of the host vehicle 1 based on the set required deceleration.

Next, the braking force distribution setting section 34 sets a target pitch angle of the own vehicle 1 according to the estimated lateral acceleration calculated by the estimated lateral acceleration calculation section 33. The braking force distribution setting unit 34 sets the target pitch angle so that the pitch angle in the direction of lowering the front end of the vehicle body becomes larger when the estimated lateral acceleration is larger than when the estimated lateral acceleration is small. For example, the target pitch angle is set such that the larger the estimated lateral acceleration, the larger the pitch angle in the direction of lowering the front end of the vehicle body.

For example, the braking force distribution setting unit 34 may set the target pitch angle using a map as illustrated in FIG. 4(a). FIG. 4(a) is a schematic diagram showing an example of a target pitch angle characteristic map for estimated lateral acceleration. The target pitch angle characteristic map can be created in advance through experiments or simulations, for example, and stored in the storage device 17b as a lookup table.

Note that in the map of FIG. 4A, the target pitch angle changes linearly with respect to the estimated lateral acceleration, but a target pitch angle characteristic map that changes nonlinearly may be used. For example, a map may be used in which the slope of the target pitch angle decreases as the estimated lateral acceleration increases, or a map in which the slope of the target pitch angle increases as the estimated lateral acceleration increases.
Further, the braking force distribution setting unit 34 may calculate the target pitch angle from the estimated lateral acceleration using an arithmetic expression instead of the target pitch angle characteristic map.

Next, the braking force distribution setting unit 34 distributes the required deceleration to the front wheels and the rear wheels based on the target pitch angle and the required deceleration.
For example, the braking force distribution setting unit 34 may determine the braking force distribution ratio between the front wheels and the rear wheels using a map as illustrated in FIG. 4(b). FIG. 4(b) is a schematic diagram showing an example of a braking force distribution ratio characteristic map with respect to the target pitch angle.

As shown in FIG. 4(b), when the target pitch angle for lowering the front end of the vehicle body is larger than when it is small, the braking force distribution ratio of the rear wheels becomes smaller. For example, the larger the target pitch angle, the smaller the rear wheel braking force distribution ratio. On the other hand, when the target pitch angle for lowering the front end of the vehicle body is larger than when it is small, the braking force distribution ratio for the front wheels becomes larger. For example, the larger the target pitch angle, the larger the braking force distribution ratio for the front wheels.

Further, as shown in FIG. 4(b), different braking force distribution ratio characteristic maps may be set depending on the magnitude of the required deceleration. The solid line shows the braking force distribution ratio characteristic map when decelerating with a relatively large required deceleration, and the broken line shows the braking force distribution ratio characteristic map when decelerating with a relatively small required deceleration.
The braking force distribution ratio characteristic map can be created in advance through experiment or simulation, for example, and stored in the storage device 17b as a look-up table.

Further, the braking force distribution setting unit 34 may calculate the braking force distribution ratio from the target pitch angle and the required deceleration using an arithmetic expression instead of the braking force distribution ratio characteristic map.
The braking force distribution setting unit 34 distributes the sum of the braking forces of the front wheels and the rear wheels to the front wheels and the rear wheels at the determined braking force distribution ratio, thereby determining the target front wheel braking force and target to be generated in the front wheels and the rear wheels, respectively. The rear wheel braking force is calculated and output to the brake controller 18b.

As a result, when the braking device is activated to decelerate the own vehicle 1, the attitude of the own vehicle 1 is controlled so that the pitch angle in the direction of lowering the front end of the vehicle becomes larger when the estimated lateral acceleration is larger than when the estimated lateral acceleration is small. can.
Specifically, when decelerating the own vehicle 1 at the same deceleration when the estimated lateral acceleration is small and large, the pitch angle in the direction of lowering the front end of the vehicle body is The attitude of the own vehicle 1 can be controlled so that it becomes larger.

(effect)
The driving control method and the operation of the driving control device 10 of the embodiment will be described with reference to FIGS. 5(a) to 5(f).
FIG. 5(a) is a schematic diagram of an example of a situation in which the own vehicle runs on a lane with a curve in front, and FIGS. 5(b) to 5(f) are respectively the situations of FIG. 5(a). 2 is a time chart of the vehicle speed, lateral acceleration, braking deceleration, estimated lateral acceleration, and pitch angle of the host vehicle 1 in FIG.

The own lane TL in Fig. 5(a) is a straight road in the section from points P1 to P3, a curved road with constant curvature in the section from points P3 to P4, and a section from points P3 to P4 in the section after point P4. It is a curved road with a larger curvature. Furthermore, assume a situation where the host vehicle 1 brakes in a straight section between points P2 and P3 before a curve.
In the time charts of FIGS. 5(b) to 5(f), times t1 to t4 indicate times when the own vehicle 1 passes through points P1 to P4, respectively. Furthermore, time t5 and time t6 are times earlier than times t3 and t4 by a forecast time (times which are earlier than times t3 and t4 by a forecast time), respectively.

As shown in FIG. 5(b), the own vehicle 1 travels at a constant vehicle speed v1 during the period from time t1 to time t2.
As shown in FIG. 5(d), from time t1 to time t2, the braking deceleration (deceleration in the longitudinal direction) is 0. During the period from time t2 to time t3, the own vehicle 1 operates the braking device and decelerates at a braking deceleration d1. In the period after time t3, the braking deceleration returns to zero.
As a result, the vehicle speed of the host vehicle 1 decreases from the vehicle speed v1 to the vehicle speed v2 as shown in FIG. 5(b) during the period from time t2 to time t3, and the host vehicle 1 runs at a constant vehicle speed v2 during the subsequent period.

As shown in FIG. 5(c), in the period from time t1 to time t3, the lateral acceleration generated in the host vehicle 1 is 0 because the road is straight in the section between points P1 and P3. In the period from time t3 to time t4, since the section between points P3 and P4 is a curved road with a constant curvature, lateral acceleration a1 occurs in the own vehicle 1, and in the period after time t4, the lateral acceleration a2 occurs in the own vehicle 1. occurs (a2>a1).
Therefore, as shown in FIG. 5E, the estimated lateral acceleration calculated by the estimated lateral acceleration calculation unit 33 during the period from time t1 to time t5 is zero. Thereafter, the estimated lateral acceleration calculation unit 33 calculates the estimated lateral acceleration a1 in the period from time t5 to time t6, and calculates the estimated lateral acceleration a2 in the period after time t6.

The braking force distribution setting section 34 sets a target pitch angle of the own vehicle 1 according to the estimated lateral acceleration calculated by the estimated lateral acceleration calculation section 33. A broken line θt in FIG. 5(f) indicates the target pitch angle set by the braking force distribution setting section 34. The target pitch angle becomes 0 in the period from time t1 to time t5, becomes the target pitch angle θ1 according to the estimated lateral acceleration a1 in the period from time t5 to time t6, and changes to the estimated lateral acceleration a2 in the period after time t6. The corresponding target pitch angle θ2 is obtained.

A solid line θr in FIG. 5(f) indicates a change in the pitch angle of the host vehicle 1 when the attitude of the host vehicle 1 is controlled based on the estimated lateral acceleration. For comparison, a dashed-dotted line θc indicates a change in pitch angle when attitude control based on estimated lateral acceleration is not performed.
As shown in FIG. 5(f), in the period from time t1 to time t2 and in the period after time t3, the vehicle 1 does not operate the braking device, so no change in the pitch angle due to deceleration occurs. Therefore, the pitch angle of the host vehicle 1 is 0 during these periods.

During the period from time t2 to time t3 when the host vehicle 1 is decelerating by operating the braking device, a change in pitch angle occurs in the body of the host vehicle 1 due to deceleration.
The braking force distribution setting unit 34 controls the braking force distribution ratio between the front wheels and the rear wheels so that the pitch angle θr of the host vehicle 1 during the period from time t2 to time t3 becomes the target pitch angle. As a result, the pitch angle θr is larger in the direction of lowering the front end of the vehicle body than the pitch angle θc=θ3 in the case where the attitude control based on the estimated lateral acceleration is not performed.

For example, as shown in FIG. 5(f), over the period from time t2 when braking by the braking device to time t3, the pitch angle θr of the own vehicle 1 is changed to the time t2 when braking by the braking device starts. The target pitch angle θ1 may be maintained at .
In this case, the pitch angle θr of the host vehicle 1 increases from 0 to θ1 at time t2, and returns to 0 again at time t3.

Alternatively, the pitch angle θr of the own vehicle 1 may be controlled so as to follow the change in the target pitch angle during the period from time t2 to time t3.
When following the target pitch angle θt (broken line) in FIG. 5(f), the pitch angle θr of the host vehicle 1 increases from 0 to θ1 at time t2, increases from θ1 to θ2 at time t6, and again at time t3. Return to 0.
By maintaining the pitch angle θr constant over the period from time t2 to time t3 during which braking by the braking device is performed, ride comfort can be maintained constant.

(motion)
FIG. 6 is a flowchart of an example of the travel control method according to the embodiment.
In step S1, the vehicle information acquisition unit 30 acquires vehicle information from the vehicle sensor 12.
In step S2, the lane boundary acquisition unit 31 acquires lane boundary information.
In step S3, the estimated lateral acceleration calculating section 33 calculates estimated lateral acceleration. For example, when the host vehicle 1 is being manually driven by the driver, the estimated lateral acceleration is calculated based on the vehicle information and lane boundary information from the vehicle sensor 12. For example, when the host vehicle 1 is automatically traveling under autonomous driving control, the estimated lateral acceleration is calculated based on the target travel trajectory and target vehicle speed profile.

In step S4, the braking force distribution setting unit 34 calculates a target pitch angle based on the estimated lateral acceleration, and sets target braking distribution for the front wheels and rear wheels that realizes the target pitch angle.
In step S5, the braking force distribution setting unit 34 determines whether a required deceleration has occurred due to autonomous driving control or the driver's brake operation. If the required deceleration occurs (step S5: Y), the process advances to S6. If the required deceleration does not occur (step S5: N), the process returns to S1.
In step S6, the braking force distribution setting unit 34 distributes the braking force to the front wheels and the rear wheels according to the set target braking distribution, and generates the braking force. The process then ends.

(Modified example)
In the above embodiment, when the braking device is operated to decelerate the vehicle 1, the pitch angle of the vehicle 1 becomes the target pitch angle by changing the braking force distribution ratio between the front wheels and the rear wheels. Although an example in which the attitude of the own vehicle 1 is controlled has been described, the means for controlling the pitch angle of the own vehicle 1 is not limited to this example.
For example, by changing the spring constants of the air suspension, hydraulic suspension, and electromagnetic suspension of the front and rear wheels of the host vehicle 1 according to the estimated lateral acceleration, the stroke amount of the front and rear wheel suspensions is changed, and the front and rear wheels of the host vehicle are The attitude of the own vehicle 1 may be controlled so that the pitch angle of 1 becomes the target pitch angle.

(Effects of embodiment)
(1) The controller 17 acquires information on the shape of the lane in which the host vehicle 1 is traveling, and calculates the lateral acceleration that occurs in the host vehicle 1 based on the detected value or target value of the vehicle speed of the host vehicle 1 and the lane shape. The estimated lateral acceleration, which is the estimated value of control.
For example, when decelerating the own vehicle 1 at the same deceleration when the estimated lateral acceleration is small and large, the downward pitch angle of the own vehicle becomes larger when the estimated lateral acceleration is large than when the estimated lateral acceleration is small. The attitude of the vehicle 1 may be controlled.

Thereby, when there is a relatively steep curve in front of the own vehicle 1, it is possible to give the occupant of the own vehicle 1 a feeling of deceleration greater than the deceleration actually occurring in the own vehicle 1. As a result, it is possible to reduce the discomfort (feeling of anxiety) caused by the difference between the feeling of deceleration felt by the occupant and the deceleration actually occurring in the own vehicle. On the other hand, when there is a relatively slow curve in front of the host vehicle 1, it is possible to give the occupants of the host vehicle 1 a feeling of deceleration smaller than the deceleration actually occurring in the host vehicle 1. As a result, it is possible to reduce the feeling of discomfort (for example, "uncomfortable ride") caused by the difference between the feeling of deceleration felt by the occupant and the deceleration actually occurring in the own vehicle.
By estimating the lateral acceleration generated in the own vehicle 1 in this way and changing the pitch angle of the own vehicle 1 according to the estimated lateral acceleration, the braking feeling given to the occupants is changed, and the The occupant can experience a sense of deceleration that matches the driving scene of the vehicle 1.

(2) The controller 17 may increase the downward pitch angle of the own vehicle by increasing the braking force distribution to the front wheels at the start of deceleration.
Thereby, the pitch angle of the host vehicle 1 can be controlled by changing the stroke amount of the suspension that occurs when the front wheels and rear wheels generate braking force.

(3) The controller 17 may calculate the estimated lateral acceleration based on the detected value of the vehicle speed of the host vehicle 1 and the lane shape.
Thereby, the estimated lateral acceleration during manual driving by the driver can be calculated.
(4) The controller 17 may set a target travel trajectory for the host vehicle 1 based on the lane shape, and calculate the estimated lateral acceleration based on the target vehicle speed and the target travel trajectory for the host vehicle 1.
This makes it possible to calculate the estimated lateral acceleration during automatic driving under autonomous driving control.

DESCRIPTION OF SYMBOLS 1... Own vehicle, 10... Travel control device, 11... Object sensor, 12... Vehicle sensor, 13... Positioning device, 14... Map database, 15... Communication device, 16... Navigation device, 17... Controller, 17a... Processor, 17b ... Storage device, 18a... Driving power source controller, 18b... Brake controller, 18c... Steering controller, 19a... Driving power source, 19b... Brake actuator, 19b... Brake actuator, 19c... Steering actuator, 30... Vehicle information acquisition unit, 31...Lane boundary acquisition section, 32...Automatic driving control section, 32a...Target trajectory generation section, 32b...Target vehicle speed setting section, 33...Estimated lateral acceleration calculation section, 34...Braking force distribution setting section

Claims (5)

Obtain information about the shape of the lane in which your vehicle is traveling,
Calculating an estimated lateral acceleration that is an estimated value of the lateral acceleration occurring in the own vehicle based on the detected value or target value of the vehicle speed of the own vehicle and the lane shape;
controlling the attitude of the own vehicle when decelerating the own vehicle so that the downward pitch angle of the own vehicle becomes larger when the estimated lateral acceleration is larger than when the estimated lateral acceleration is small;
A travel control method characterized by: When the host vehicle is decelerated at the same deceleration when the estimated lateral acceleration is small and when the estimated lateral acceleration is large, the downward pitch angle of the host vehicle is larger when the estimated lateral acceleration is large than when the estimated lateral acceleration is small. The travel control method according to claim 1, further comprising controlling the attitude of the host vehicle. 2. The driving control method according to claim 1, wherein the downward pitch angle of the own vehicle is increased by increasing the distribution of braking force to the front wheels at the start of deceleration. setting a target travel trajectory for the host vehicle based on the lane shape;
The travel control method according to any one of claims 1 to 3, wherein the estimated lateral acceleration is calculated based on the target vehicle speed of the own vehicle and the target travel trajectory. Information on the lane shape of the lane in which the own vehicle is traveling is acquired, and estimated lateral acceleration is an estimated value of the lateral acceleration occurring in the own vehicle based on the detected value or target value of the vehicle speed of the own vehicle and the lane shape. A controller that calculates acceleration and controls the attitude of the own vehicle when decelerating the own vehicle so that the downward pitch angle of the own vehicle becomes large when the estimated lateral acceleration is larger than when the estimated lateral acceleration is small. A travel control device comprising:

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