Vehicle control method and vehicle control device

Abstract

To suppress a discomfort felt by an occupant when a vehicle turns, caused by a load gravity center position moving in association with acceleration-deceleration of the vehicle.SOLUTION: A vehicle control method includes: estimating acceleration-deceleration occurring to a vehicle; (S1): calculating a movement amount of a load gravity center position in a vehicular front-rear direction on the basis of the estimated acceleration-deceleration (S3); estimating a load gravity center position in the front-rear direction on the basis of the calculated movement amount (S4); setting target lateral force, target yaw moment and target yaw rate (S2); setting a target body slip angle on the basis of the target yaw rate and load gravity center position so that a yaw rotation center of the vehicle is consistent with the estimated load gravity center position (S5); and steering the front and rear wheels so as to obtain a target steering angle that realize the target lateral force, target yaw moment, target yaw rate and target body slip angle (S6-S8)SELECTED DRAWING: Figure 7

Description

Technical Field

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

Background Art

[0002] In Patent Document 1, a technique is proposed for arbitrarily setting the turning center of a vehicle in a four-wheel independent steering vehicle to any one of a total of nine positions, namely, four positions of the positions of each driving wheel, four positions of the center positions between adjacent driving wheels, and one position of the center of gravity position of the vehicle area.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the vehicle turns, it is considered that a lateral force acts as a centripetal force on the point where the loads on the wheels balance (that is, the center of gravity position of the entire load on the front and rear wheels) in the vehicle as a rigid body. In the following description, the point where the loads on the wheels balance may be referred to as the "load center of gravity position". Also, the position of the center of gravity of the vehicle (that is, the point of action of the resultant force of the gravity acting on each part of the vehicle) may be referred to as the "static center of gravity position". In the following description, the load center of gravity position and the static center of gravity position in the longitudinal direction of the vehicle will be described.

[0005] When the vehicle is stationary or moving at a constant speed, the load center of gravity position and the static center of gravity position in the longitudinal direction of the vehicle are substantially the same. On the other hand, when the vehicle is accelerating, the load center of gravity position moves backward from the static center of gravity position, and when the vehicle is decelerating, the load center of gravity position moves forward from the static center of gravity position. Therefore, if the center of rotation of the yaw rotation during a vehicle turn (hereinafter sometimes referred to as the "yaw center") is fixed, the position where the centripetal force acts on the vehicle (i.e., the center of gravity of the load) will be shifted from the position of the yaw center.

[0006] Thus, when the position where the centripetal force acts on a vehicle is misaligned with the position of the center of rotation of the yaw rotation, a sense of disconnection can arise between the turning motion (revolution) caused by the centripetal force and the yaw rotational motion (rotation) around the yaw center, which can cause discomfort to the occupants. For example, when turning while decelerating, the yaw center is located behind the position where the centripetal force acts, which can give the sensation that the rear of the vehicle is sliding. Conversely, when turning while accelerating, the sensation that the front of the vehicle is sliding may occur. The present invention aims to suppress the discomfort experienced by occupants during turns caused by the shift in the center of gravity of the load due to the acceleration and deceleration of the vehicle. [Means for solving the problem]

[0007] In one embodiment of the present invention, a vehicle control method is used to estimate the acceleration and deceleration of a vehicle, calculate the amount of movement of the load center of gravity position, which is the position of the total center of gravity of the load on the front and rear wheels, in the longitudinal direction of the vehicle based on the estimated acceleration and deceleration, estimate the load center of gravity position in the longitudinal direction of the vehicle during acceleration and deceleration based on the calculated amount of movement, set a target lateral force, target yaw moment, and target yaw rate based on the steering angle of the steering wheel or the target driving trajectory of the vehicle, set a target vehicle slip angle based on the target yaw rate and the estimated load center of gravity position, set a target vehicle slip angle so that the yaw rotation center of the vehicle is at the estimated load center of gravity position, calculate the target steering angles of the front and rear wheels that realize the target lateral force, target yaw moment, target yaw rate, and target vehicle slip angle, and steer the front and rear wheels so that their steering angles become the target steering angles. [Effects of the Invention]

[0008] According to the present invention, the discomfort experienced by occupants during turns due to the shift in the center of gravity caused by the acceleration and deceleration of the vehicle can be suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of a schematic configuration of a vehicle equipped with the vehicle control device of the embodiment. [Figure 2] This is an explanatory diagram of the center of gravity of the load. [Figure 3] (a) and (b) are schematic diagrams of the center of gravity of the load during acceleration and deceleration. [Figure 4] (a) and (b) are schematic diagrams illustrating the vehicle control method of the embodiment. [Figure 5] Figure 1 is a block diagram showing an example of the functional configuration of a vehicle motion controller. [Figure 6] This is an explanatory diagram illustrating an example of a method for estimating the position of the center of gravity of the load in the longitudinal direction of a vehicle. [Figure 7] This is a flowchart of an example of a vehicle control method according to the embodiment. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings. Note that the drawings are schematic and may differ from actual ones. Furthermore, the embodiments of the present invention described below are illustrative examples of devices and methods for realizing the technical concept of the present invention, and the technical concept of the present invention is not limited to the structure, arrangement, etc., of the components described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims described in the patent claims.

[0011] (composition) Figure 1 shows an example of a schematic configuration of a vehicle equipped with the vehicle control device of the embodiment. Vehicle 1 is a four-wheel steering vehicle capable of steering the front wheels 2F (left front wheel 2FL and right front wheel 2FR) and the rear wheels (left rear wheel 2RL and right rear wheel 2RR). The vehicle control device 10 controls the front wheel steering angle δF of the front wheels 2F, the rear wheel steering angle δR of the rear wheels 2R, and the driving force and braking force of vehicle 1. Vehicle 1 may be a vehicle having a function to perform automatic driving control that automatically controls at least one of the steering angle, driving force, or braking force. The automatic driving control of Vehicle 1 may be autonomous driving control that drives Vehicle 1 automatically without the involvement of an occupant (e.g., driver). Alternatively, the automatic driving control of Vehicle 1 may be driver assistance control that assists the driver in driving Vehicle 1 by partially automatically controlling the steering angle, driving force, or braking force. For example, driver assistance control may include constant speed driving control, lane keeping control, merging assistance control, automatic lane change function, automatic braking, and preceding vehicle following control. Vehicle 1 may be a vehicle that does not have the function to perform automatic driving control.

[0012] 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 Satellite System (GNSS) receiver. The GNSS receiver is, for example, a GPS receiver, and measures the current position of the vehicle 1 by receiving radio waves from navigation satellites.

[0013] Map DB12 stores map data. The map data stored in Map DB12 may be high-precision map data suitable for use as map information for autonomous driving. High-precision map data has higher accuracy than navigation map data and includes information at the lane level. The map data stored in Map DB12 may also be navigation map data. Navigation map data includes information at the road level.

[0014] The external sensor 13 detects various information (surrounding environment information) about the surrounding environment around the vehicle 1. For example, the external sensor 13 detects objects around the vehicle 1. The external sensor 13 detects the surrounding environment of the vehicle 1, such as the objects existing 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 exist. The external sensor 13 outputs the detected surrounding environment information to the driving control controller 20 as the surrounding environment information. The external sensor 13 may include a monocular camera such as a color camera with a full HD resolution. The camera captures an image including the recognition target of the surrounding environment of the vehicle 1 and outputs the captured image to the driving control controller 20 as the surrounding environment information. Further, the external sensor 13 may include a distance measuring device such as a laser range finder (LRF), a radar, or a laser radar of LiDAR (Light Detection and Ranging). The distance measuring device detects, for example, the relative position determined by the relative distance and direction from the objects existing around the host vehicle. The distance measuring device outputs the detected distance measurement data to the driving control controller 20 as the surrounding environment information.

[0015] The vehicle sensor 14 detects various information (vehicle information) obtained from the vehicle 1. The vehicle sensor 14 includes, for example, a vehicle speed sensor that detects the traveling speed (vehicle speed) V of the vehicle 1, a wheel speed sensor that detects the rotational speed of each tire provided in the vehicle 1, a three-axis acceleration sensor (G sensor) that detects the acceleration (including deceleration) in the three-axis directions of the vehicle 1, a steering angle sensor that detects the steering angle θs 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 Ac which is the operation amount of the accelerator pedal of the vehicle 1, and a brake sensor that detects the brake operation amount Br which is the operation amount of the brake pedal by the driver. The vehicle sensor 14 outputs the detected vehicle information to the vehicle motion controller 15 and the driving control controller 20.

[0016] The vehicle motion controller 15 is an electronic control unit (ECU: Electronic Control Unit) that controls the front wheel steering angle δF, the rear wheel steering angle δR, the driving force, and the braking force of the vehicle 1. The drive source controller 16 is an ECU that generates the target drive torque Tdt indicated by the control signal output from the vehicle motion controller 15 in the drive power source 21. The drive power source 21 may include, for example, one or both of a drive motor and an internal combustion engine (engine).

[0017] The brake controller 17 is an ECU that generates the target hydraulic pressure Pt indicated by the control signal output from the vehicle motion controller 15 in the hydraulic actuator 22 interposed between the master cylinder and the brake calipers 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 indicated by the control signal output from the vehicle motion controller 15. The driving control controller 20 is an ECU that performs autonomous driving control for automatically driving the vehicle 1 without the involvement of the occupant or driving support control for assisting the driver in driving the vehicle 1 by partially automatically controlling the steering angle, the driving force, or the braking force.

[0018] The vehicle motion controller 15, the drive source controller 16, the brake controller 17, the front wheel steering controller 18, the rear wheel steering controller 19, and the driving control controller 20 each include a processor 15a to 20a and peripheral components such as storage devices 15b to 20b. The processors 15a to 20a may be, for example, a CPU (Central Processing Unit) or a 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 registers, cache memory, and memory such as ROM (Read Only Memory) and RAM (Random Access Memory) used as main memory.

[0019] 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, as described below, are realized, for example, by processors 15a to 20a executing computer programs stored in memory 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 driving control controller 20 may be formed by dedicated hardware for performing 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 driving control controller 20 may have functional logic circuits (such as programmable logic devices (PLDs) like field-programmable gate arrays (FPGAs)) set up in general-purpose semiconductor integrated circuits. If Vehicle 1 is a vehicle without autonomous driving or driver assistance functions, the positioning device 11, map database 12, external sensor 13, and driving control controller 20 may be omitted.

[0020] Next, we will explain the control by the vehicle motion controller 15. As mentioned above, a centripetal force (lateral force) acts on the turning vehicle 1. If we consider the vehicle 1 as a single rigid body, this centripetal force is thought to act on the center of gravity of the loads at which each load on the wheels balances out (i.e., the center of gravity of the total loads on the front and rear wheels). Refer to Figure 2 to explain the center of gravity of the load. Currently, the positions of the left front wheel 2FL, right front wheel 2FR, left rear wheel 2RL, and right rear wheel 2RR are (x1, y1), (x2, y2), (x3, y3), and (x4, y4), respectively, and the loads on the left front wheel 2FL, right front wheel 2FR, left rear wheel 2RL, and right rear wheel 2RR are L1, L2, L3, and L4, respectively.

[0021] The position (xG, yG) of the load center of gravity PLG, which is the center of gravity of the entire load applied to 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)

[0022] When vehicle 1 is stationary or moving at a constant velocity, the load center of gravity position PLG in the longitudinal direction of the vehicle is approximately the same as the static center of gravity position PG of the vehicle (i.e., the point of application of the resultant force of gravity acting on each part of the vehicle). Figures 3(a) and 3(b) are schematic diagrams of the load center of gravity position PLG during acceleration and deceleration, respectively. When vehicle 1 is accelerating, the load center of gravity position PLG moves behind the static center of gravity position PG, and when vehicle 1 is decelerating, the load center of gravity position PLG moves in front of the static center of gravity position PG. Therefore, if the position of the yaw center Pyc, which is the center of rotation for yaw rotation during vehicle turning, is fixed, the position of the yaw center Pyc will be offset from the position where the centripetal force (lateral force Fy) acts on the vehicle 1 (the center of gravity of the load, PLG). For example, in the example shown in Figure 4(a), the position of the yaw center Pyc is set to the static center of gravity PG, so the position of the yaw center Pyc is offset from the center of gravity of the load, PLG, where the centripetal force acts on the vehicle 1.

[0023] Thus, if the position of the yaw center Pyc is offset from the position PLG where the centripetal force acts, it can create a feeling that the turning motion (revolution) and yaw rotation (rotation) of the vehicle, caused by the centripetal force, are not correlated, which can cause discomfort to the occupants. For example, when turning while decelerating, the yaw center Pyc is located behind the PLG where the centripetal force acts, which can create a feeling that the rear of the vehicle is sliding. Conversely, when turning while accelerating, a feeling that the front of the vehicle is sliding may occur.

[0024] Therefore, when the vehicle 1 turns, the vehicle motion controller 15 aligns the position of the yaw center Pyc in the longitudinal direction of the vehicle with the load center of gravity position PLG, as shown in Figure 4(b). Specifically, the acceleration / deceleration ax of vehicle 1 is estimated, the displacement lw of the load center of gravity position PLG in the longitudinal direction of the vehicle is calculated based on the estimated acceleration / deceleration ax, and the load center of gravity position PLG in the longitudinal direction of the vehicle is estimated based on the displacement lw. In addition, the target lateral force Fyt, target yaw moment Mzt, and target yaw rate γt are set based on the steering angle θs of the steering wheel or the target driving trajectory of vehicle 1.

[0025] The vehicle motion controller 15 sets the target vehicle slip angle βt based on the target yaw rate γt and the load center of gravity position PLG, so that the position of the yaw center Pyc becomes the estimated load center of gravity position PLG. Then it calculates the target front wheel steering angle δFt and target rear wheel steering angle δRt that achieve the target lateral force Fyt, target yaw moment Mzt, target yaw rate γt, and target vehicle slip angle βt. The front wheel steering controller 18 and rear wheel steering controller 19 steer the front wheel 2F and rear wheel 2R so that the front wheel steering angle δF and rear wheel steering angle δR become the target steering angles δFt and δRt. This allows the position of the yaw center Pyc of vehicle 1's yaw rotation (rotation) to coincide with the position where the centripetal force of vehicle 1's turning motion (revolution) acts. As a result, the feeling of unnaturalness caused by the lack of correlation between turning motion (revolution) and yaw rotation (rotation) can be suppressed.

[0026] Figure 5 is a block diagram of an example of the functional configuration of the vehicle motion controller 15 shown in Figure 1. The vehicle motion controller 15 includes a target acceleration / deceleration calculation unit 30, a turning target value setting unit 31, a torque conversion unit 32, a hydraulic pressure conversion unit 33, a displacement calculation unit 34, a load center of gravity position estimation unit 35, a vehicle body slip angle estimation unit 36, and a steering angle calculation unit 37. The target acceleration / deceleration calculation unit 30 calculates a target acceleration / deceleration ax to be generated in the vehicle 1 based on the accelerator pedal operation amount Ac and the brake pedal operation amount Br. The target acceleration / deceleration ax is the target value of the degree of acceleration / deceleration to be generated in the vehicle 1 in the future, and is an estimated value of the degree of acceleration / deceleration of the vehicle 1. The target acceleration / deceleration calculation unit 30 calculates the target driving force Fdt and the 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 the displacement calculation unit 34, and outputs the target driving force Fdt and target braking force Fbt to the torque conversion unit 32 and hydraulic pressure conversion unit 33, respectively.

[0027] The turning target value setting unit 31 sets the target lateral force Fyt, target yaw moment Mzt, and target yaw rate γt based on the steering wheel steering angle θs and the vehicle motion model. The turning target value setting unit 31 outputs the target yaw rate γt to the vehicle slip angle estimation unit 36 ​​and the steering angle calculation unit 37, and outputs the target lateral force Fyt and target yaw moment Mzt to the steering angle calculation unit 37. The accelerator pedal operation amount Ac, brake pedal operation amount Br, and steering angle θs may also be the amount of accelerator pedal operation, brake pedal operation amount, and steering wheel steering angle operated by the driver. The accelerator pedal operation amount Ac, brake pedal operation amount Br, and steering angle θs may also be the amount of accelerator pedal operation, brake pedal operation amount, and steering wheel steering angle operated by autonomous driving control or driving assistance control by the driving control controller 20.

[0028] For example, when performing autonomous driving control, once a planned driving route from the current location to the destination is set by a navigation system or the like, the driving control controller 20 generates a target driving trajectory for vehicle 1 and a target vehicle speed profile for vehicle 1 traveling along the target driving trajectory, based on map data stored in map DB 12, surrounding environment information output by external sensor 13, and vehicle information output by vehicle sensor 14. For example, when performing driver assistance control, the driver control controller 20 generates at least one of a target driving trajectory and a target vehicle speed profile based on the surrounding environment information output by the external sensor 13 and the vehicle information output by the vehicle sensor 14. For example, in merging assistance control and automatic lane change functions, both a target driving trajectory and a target vehicle speed profile may be generated. In lane keeping control, only a target driving trajectory may be generated. In constant speed driving control, preceding vehicle following control, and automatic braking, a target vehicle speed profile may be generated.

[0029] The driving control controller 20 calculates the steering angle θs, accelerator operation amount Ac, and brake operation amount Br required to drive the vehicle 1 according to the target driving trajectory and / or target vehicle speed profile, and may operate the steering wheel, accelerator pedal, and brake pedal based on these operation amounts. Furthermore, when performing autonomous driving control, the driving control controller 20 may calculate a target acceleration / deceleration ax instead of the accelerator operation amount Ac and brake operation amount Br. In this case, the driving control controller 20 may directly output the target acceleration / deceleration ax to the movement amount calculation unit 34.

[0030] Furthermore, the driving control controller 20 may calculate target turning values ​​such as target lateral force Fyt, target yaw moment Mzt, and target yaw rate γt. For example, the driving control controller 20 may calculate a target lateral force Fyt for vehicle 1 to travel along a target trajectory at a speed that conforms to the target vehicle speed profile. The turning target value setting unit 31 may set a target yaw moment Mzt and a target yaw rate γt based on the target lateral force Fyt.

[0031] The torque conversion unit 32 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 to the drive source controller 16 that instructs the target driving torque Tdt. The hydraulic pressure conversion unit 33 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 to the brake controller 17 that instructs the target hydraulic pressure Pt.

[0032] The displacement calculation unit 34 calculates the displacement lw of the load center of gravity position PLG in the longitudinal direction of the vehicle during acceleration and deceleration based on the target acceleration / deceleration speed ax. Figure 6 is an explanatory diagram of an example of a method for estimating the load center of gravity position in the longitudinal direction of the vehicle. In Figure 6, l is the wheelbase length, lR is the length from the static center of gravity position PG of the vehicle 1 to the rear axle, and lF is the length from the static center of gravity position PG to the front axle. The displacement calculation unit 34 calculates the front wheel load Wf, which is the load on the front wheel 2F, and the rear wheel load Wr, which is the load on the rear wheel 2R, using the following equations (3) and (4).

number

[0033] In equations (3) and (4) above, m is the vehicle mass of vehicle 1, g is the acceleration due to gravity, and κ is the longitudinal load transfer coefficient determined in advance as a design value or experimental value. The displacement calculation unit 34 calculates the displacement lw of the load center of gravity position PLG from the ratio of the front wheel load Wf to the rear wheel load Wr. For example, the displacement calculation unit 34 may calculate the displacement lw using the following equation (5). The sign of the displacement lw is positive (plus) when the load center of gravity position PLG is forward of the static center of gravity position PG, and negative (minus) when the load center of gravity position PLG is forward of the static center of gravity position PG.

number

[0034] Refer to Figure 5. The load center of gravity position estimation unit 35 estimates the load center of gravity position PLG by moving the static center of gravity position PG in the longitudinal direction of the vehicle by a displacement of lw. The load center of gravity position estimation unit 35 sets the position of the target yaw center Pyct, which is the target value of the position of the yaw center Pyc, to the estimated load center of gravity position PLG. The load center of gravity position estimation unit 35 outputs the deviation lyct of the target yaw center Pyct from the static center of gravity position PG in the longitudinal direction of the vehicle to the vehicle body slip angle estimation unit 36. The sign of the deviation lyct is set to be positive (plus) when the target yaw center Pyct is forward of the static center of gravity position PG, and negative (minus) when the target yaw center Pyct is forward of the static center of gravity position PG. The load center of gravity position estimation unit 35 may output the displacement amount lw as the deviation lyct. In this case, a limiter may be provided to limit the output value of the load center of gravity position estimation unit 35 in order to restrict the range of the position of the target yaw center Pyct. Alternatively, a rate limiter may be provided to limit the rate of change of the output value of the load center of gravity position estimation unit 35 in order to restrict the rate of change of the position of the target yaw center Pyct.

[0035] The vehicle body slip angle estimation unit 36 ​​calculates the target vehicle body slip angle βt based on the deviation lyct output from the load center of gravity position estimation unit 35, the target yaw rate γt, and the vehicle speed V using the following equation (6).

number

[0036] The steering angle calculation unit 37 calculates the target wheel slip angle βFt for the front wheel 2F and the target wheel slip angle βRt for the rear wheel 2R based on the target lateral force Fyt and target yaw moment Mzt using the following equations (7) and (8).

number

[0037] The steering angle calculation unit 37 calculates the target front wheel steering angle δFt and the target rear wheel steering angle δRt based on the vehicle speed V, the target yaw rate γt, the target vehicle slip angle βt, and the target wheel slip angles βFt and βRt using the following equations (9) and (10).

number

[0038] (operation) Figure 7 is a flowchart of an example of a vehicle control method according to the embodiment. In step S1, the target acceleration / deceleration calculation unit 30 calculates the target acceleration / deceleration ax based on the accelerator pedal operation amount Ac and the brake pedal operation amount Br. In step S2, the turning target value setting unit 31 sets the target lateral force Fyt, the target yaw moment Mzt, and the target yaw rate γt. In step S3, the displacement calculation unit 34 calculates the amount of displacement lw of the load center of gravity position PLG in the longitudinal direction of the vehicle during acceleration and deceleration.

[0039] In step S4, the load centroid position estimation unit 35 sets the position of the target yaw center Pyct to the load centroid position PLG. In step S5, the vehicle body slip angle estimation unit 36 ​​calculates the target vehicle body slip angle βt. In step S6, the steering angle calculation unit 37 calculates the target wheel slip angle βFt for the front wheel 2F and the target wheel slip angle βRt for the rear wheel 2R.

[0040] In step S7, the steering angle calculation unit 37 calculates the target front wheel steering angle δFt and the target rear wheel steering angle δRt. In step S8, the front wheel steering controller 18 and the rear wheel steering controller 19 steer the front wheel 2F and the rear wheel 2R so that the front wheel steering angle δF and the rear wheel steering angle δR become the target steering angles δFt and δRt. The process then ends.

[0041] (Effects of the embodiment) (1) The vehicle motion controller 15 estimates the acceleration and deceleration occurring in the vehicle 1, calculates the amount of movement of the load center of gravity position, which is the position of the center of gravity of the total load applied to the front wheels 2F and rear wheels 2R, in the longitudinal direction of the vehicle based on the estimated acceleration and deceleration, estimates the load center of gravity position in the longitudinal direction of the vehicle during acceleration and deceleration based on the calculated amount of movement, sets a target lateral force, target yaw moment and target yaw rate based on the steering angle of the steering wheel or the target driving trajectory of the vehicle 1, sets a target vehicle slip angle so that the yaw rotation center of the vehicle 1 is at the estimated load center of gravity position based on the target yaw rate and the estimated load center of gravity position, and calculates the target steering angles of the front wheels 2F and rear wheels 2R that realize the target lateral force, target yaw moment and target yaw rate and target vehicle slip angle. The front wheel steering controller 18 and the rear wheel steering controller 19 steer the front wheel 2F and the rear wheel 2R so that their steering angles become the target steering angles. This allows the position of the yaw rotation center of vehicle 1's yaw rotation (rotation) to coincide with the position where the centripetal force of vehicle 1's turning motion (revolution) acts. As a result, the feeling of unnaturalness caused by the lack of correlation between turning motion (revolution) and yaw rotation (rotation) can be suppressed.

[0042] (2) The vehicle sensor 14 may detect the amount of operation of the accelerator pedal or brake pedal of the vehicle 1. The vehicle motion controller 15 may estimate the acceleration or deceleration that occurs in the vehicle 1 based on the detected amount of operation of the accelerator pedal or brake pedal. From the time the controller outputs the target drive torque, target hydraulic pressure, and target steering angle until the actual vehicle behavior is generated in vehicle 1, delays occur due to vehicle dynamics, calculation time, and communication time. Therefore, if the actual vehicle behavior is detected from the acceleration sensor and suspension stroke amount to calculate the load center of gravity position PLG, the setting of the target yaw center Pyct may lag behind acceleration and deceleration, potentially causing a discrepancy between the position where the centripetal force acts on the vehicle and the position of the center of rotation of the yaw rotation. By calculating the load center of gravity position PLG based on the acceleration / deceleration amount estimated from the amount of operation of the accelerator pedal or brake pedal, the delay in setting the target yaw center Pyct can be suppressed.

[0043] (3) The vehicle motion controller 15 may calculate the loads on the front wheels 2F and rear wheels 2R based on the estimated longitudinal acceleration and deceleration of the vehicle 1 and the longitudinal load transfer coefficients identified in advance. The amount of movement of the load center of gravity position may be calculated from the ratio of the load on the front wheels 2F to the load on the rear wheels 2R. This allows us to estimate the position of the center of gravity of the load as it moves during acceleration and deceleration. (4) The target driving trajectory may be set by autonomous driving control that automatically drives the vehicle 1 or by driving assistance control that automatically controls the steering angle. This makes it possible to suppress the discomfort felt by the occupants during turns, even when the vehicle 1 is turning under autonomous driving control or driver assistance control, due to the shift in the center of gravity caused by the acceleration and deceleration of the vehicle. [Explanation of symbols]

[0044] 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 force source, 22...Hydraulic actuator, 23...Front wheel steering actuator, 24...Rear wheel steering actuator, 30...Target acceleration / deceleration calculation unit, 31...Turning target value setting unit, 32...Torque conversion unit, 33...Hydraulic conversion unit, 34...Displacement amount calculation unit, 35...Load center of gravity position estimation unit, 36...Vehicle body slip angle estimation unit, 37...Steering angle calculation unit

Claims

1. Estimate the acceleration and deceleration occurring in the vehicle, Based on the estimated acceleration and deceleration, the loads on the front and rear wheels are calculated. From the ratio of the load on the front wheels to the load on the rear wheels, the amount of movement in the longitudinal direction of the vehicle of the load center of gravity, which is the position of the center of gravity of the total load on the front and rear wheels, is calculated. Based on the calculated displacement, the position of the center of gravity of the load in the longitudinal direction of the vehicle during acceleration and deceleration is estimated. Based on the steering angle of the steering wheel or the target trajectory of the vehicle, the target lateral force, target yaw moment, and target yaw rate are set. Based on the target yaw rate and the estimated center of gravity of the load, the target vehicle slip angle is set such that the yaw rotation center of the vehicle is at the estimated center of gravity of the load. The target steering angles of the front and rear wheels are calculated to achieve the target lateral force, target yaw moment, target yaw rate, and target vehicle slip angle. The front wheel and the rear wheel are steered so that their steering angles become the target steering angles. A vehicle control method characterized by the following:

2. The amount of operation of the accelerator pedal or brake pedal of the vehicle is detected, The acceleration and deceleration occurring in the vehicle are estimated based on the detected manipulated variable. The vehicle control method according to feature 1.

3. The vehicle control method according to Claim 1, characterized in that the target driving trajectory is set by autonomous driving control that drives the vehicle automatically or by driving assistance control that automatically controls the steering angle.

4. The vehicle control method according to any one of claims 1 to 3, characterized in that the loads of the front wheels and the rear wheels are calculated based on the estimated longitudinal acceleration and deceleration of the vehicle and the longitudinal load transfer coefficients identified in advance.

5. A controller that estimates the acceleration and deceleration occurring in a vehicle, calculates the loads on the front and rear wheels based on the estimated acceleration and deceleration, calculates the amount of movement of the load center of gravity position, which is the position of the total load on the front and rear wheels, in the longitudinal direction of the vehicle from the ratio of the loads on the front and rear wheels, estimates the load center of gravity position in the longitudinal direction of the vehicle during acceleration and deceleration based on the calculated amount of movement, sets a target lateral force, target yaw moment, and target yaw rate based on the steering angle of the steering wheel or the target driving trajectory of the vehicle, sets a target vehicle slip angle based on the target yaw rate and the estimated load center of gravity position, such that the yaw rotation center of the vehicle is at the estimated load center of gravity position, and calculates the target steering angles of the front and rear wheels that realize the target lateral force, target yaw moment, target yaw rate, and target vehicle slip angle. A steering actuator that steers the front wheel and the rear wheel so that the steering angle of the front wheel and the rear wheel becomes the target steering angle, A vehicle control device characterized by comprising:

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