Vehicle control device and vehicle control method

Abstract

This technology improves driver comfort through roll control and enhances the ability to follow a target trajectory in autonomous driving control. [Solution] The vehicle control device 10, which controls a vehicle behavior control device 16 capable of controlling the roll movement of the vehicle body, includes an acquisition unit that acquires information indicating a roll control gain for driving the vehicle behavior control device 16 to move the vehicle body in the roll direction, and a calculation unit that, when performing automatic driving control, calculates a target control value to be executed in automatic driving control based on the information indicating the roll control gain.

Description

[Technical Field]

[0001] This invention relates to a technology for performing automatic driving control of a vehicle and roll control of the vehicle body. [Background technology]

[0002] Patent Document 1 discloses a vehicle cornering control device that performs automatic driving in accordance with the dynamic change characteristics of the turning behavior. This vehicle cornering control device defines the relationship between the tire slip angle and lateral force as a reference characteristic line, and calculates the slope of the tangent to the reference characteristic line at the coordinate position corresponding to the slip angle or lateral force as the cornering power. Furthermore, this cornering power is used to set the distribution ratio of the vehicle's yaw moment control and deceleration control to realize the vehicle's target turning behavior. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2015-199433 [Overview of the project] [Problems that the invention aims to solve]

[0004] In the technology disclosed in Patent Document 1, the distribution ratio of yaw moment control and deceleration control is set using cornering power calculated based on slip angle and lateral force. However, if roll control is performed to move the vehicle body in the roll direction using an active suspension system or the like during cornering, the suspension characteristics such as camber angle may change, potentially causing a deviation from the target cornering behavior.

[0005] The objective of the present invention is to provide a technology that can improve driver comfort through roll control and improve the ability to follow a target trajectory in automated driving control. [Means for solving the problem]

[0006] In order to solve the above problems, an aspect of the present invention is a vehicle control device that controls a vehicle behavior control device capable of controlling the movement of a vehicle body in the roll direction, the vehicle control device including: an acquisition unit that acquires information indicating a roll control gain for driving the vehicle behavior control device to move the vehicle body in the roll direction; and a calculation unit that calculates a target control value to be executed in the automatic driving control based on the information indicating the roll control gain when the automatic driving control is being executed.

[0007] Another aspect of the present invention is a vehicle control method. This method is a vehicle control method executed by a vehicle control device that controls a vehicle behavior control device capable of controlling the movement of a vehicle body in the roll direction, the method including: a step of acquiring information indicating a roll control gain for driving the vehicle behavior control device to move the vehicle body in the roll direction; and a step of calculating a target control value to be executed in the automatic driving control based on the acquired roll control gain when the automatic driving control is being executed.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a technique that improves the comfort of a driver by roll control and improves the followability with respect to a target trajectory in automatic driving control.

Brief Description of the Drawings

[0009] [Figure 1] It is a diagram showing the functional configuration of a vehicle control system of an embodiment. [Figure 2] It is a diagram showing the relationship between a roll control gain and an equivalent cornering power. [Figure 3] It is a diagram showing the relationship between a roll control gain and a lateral force delay time constant. [Figure 4] It is a diagram showing a turning state of a vehicle in a two-wheel model. [Figure 5] It is a flowchart of a vehicle control method of an embodiment.

Modes for Carrying Out the Invention

[0010] FIG. 1 is a diagram showing the functional configuration of the vehicle control system 1 of the embodiment. In FIG. 1, each element described as a functional block that performs various processes can be hardware-wise composed of circuit blocks, memories, and other LSIs, and software-wise realized by programs loaded in memories and the like. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by only hardware, only software, or combinations thereof, and are not limited to any of them.

[0011] The vehicle control system 1 executes autonomous driving control that can drive autonomously. In the autonomous driving control, the vehicle control system 1 executes follow-up control to follow a preceding vehicle and cruise control to travel on a driving lane at a predetermined vehicle speed. The vehicle control system 1 includes a vehicle control device 10, a driving state detection sensor 12, an object detection sensor <00E59084>14, a vehicle behavior control device 16, and a driving device 18.

[0012] The driving state detection sensor 12 detects the driving state of the vehicle. The driving state detection sensor 12 includes a vehicle speed sensor, a steering angle sensor, an acceleration sensor, a brake pressure sensor, and the like, and transmits the result of detecting the driving state of the vehicle to the vehicle control device 10. <00E59084>

[0013] The object detection sensor 14 includes an in-vehicle camera, a millimeter-wave radar, a lidar, a sound wave sensor, and the like, and detects an object located around the vehicle. The object detection sensor 14 may transmit information indicating the positional relationship between the object and the host vehicle to the vehicle control device 10 as information about the object, or may transmit merely sensor values to the vehicle control device 10 as information about the object.

[0014] The vehicle behavior control device 16 is, for example, an active stabilizer device. The active stabilizer device may be provided on the front wheel side and the rear wheel side, or only on the front wheel side. The active stabilizer device has both ends connected to the left and right wheels, for example, the lower arms. The active stabilizer device has a right stabilizer bar, a left stabilizer bar, and an electric actuator that connects the right stabilizer bar and the left stabilizer bar so that they can rotate relative to each other. The vehicle control device 10 can apply a force in the roll direction to the vehicle body by driving the electric actuator to rotate the right stabilizer bar and the left stabilizer bar relative to each other.

[0015] Furthermore, the vehicle behavior control device 16 may be an active suspension system. The active suspension system may be an air suspension system or an electrically or hydraulically operated fully active suspension system. The active suspension system can move the vehicle body in the roll direction by displacing one of the left or right wheels in the vertical direction. In any case, the vehicle behavior control device 16 controls the roll direction movement of the vehicle body.

[0016] The running gear 18 includes a driving means for applying driving force to the wheels and rotating the wheels to move the vehicle forward, a steering means for turning the wheels, and a braking means for applying braking force to the wheels. The driving means may be an engine, a motor, or a combination thereof. The running gear 18 may be driven by the driver's operation or by automatic driving control. In other words, automatic driving control is performed in accordance with the driver's instructions.

[0017] The vehicle control device 10 includes a roll control device 20 and a driving control device 22. The roll control device 20 controls the vehicle behavior control device 16 to perform roll control, which moves the vehicle body in the roll direction. The driving control device 22 drives the running gear 18 to perform automatic driving control. The roll control device 20 and the driving control device 22 can communicate with each other via in-vehicle communication. Note that the roll control device 20 and the driving control device 22 are not limited to separate ECUs (Electronic Control Units), but may be an integrated ECU.

[0018] The roll control device 20 comprises an acquisition unit 24, a gain calculation unit 26, a drive control unit 28, and a communication unit 30. The acquisition unit 24 acquires the detection results of the driving state detection sensor 12. The detection results include the lateral acceleration of the vehicle body or the velocity of the vehicle body in the roll direction, which is mounted on a spring. The velocity of the vehicle body in the roll direction may be calculated based on the lateral acceleration. Lateral acceleration is the acceleration in the left-right direction of the vehicle.

[0019] The gain calculation unit 26 acquires information indicating the roll control gain for driving the vehicle behavior control device 16 based on the vehicle's roll speed. The information indicating the roll control gain is an index indicating the magnitude by which the vehicle behavior control device 16 moves the vehicle in the roll direction, and indicates the magnitude of the roll control performed by the vehicle behavior control device 16 to suppress the vehicle's roll speed. The information indicating the roll control gain may be the absolute value of the force or torque of the actuator of the vehicle behavior control device 16, the ratio of the absolute value of the force or torque of that actuator to the lateral acceleration, the target roll angle, or the target roll angle with respect to the lateral acceleration.

[0020] The drive control unit 28 drives the vehicle behavior control device 16 according to the roll control gain. This suppresses the tilt of the vehicle body in the roll direction when the vehicle turns, improving the planar motion characteristics. The communication unit 30 periodically transmits information indicating the roll control gain calculated by the gain calculation unit 26 to the driving control device 22.

[0021] The driving control device 22 comprises a communication unit 32, an estimation unit 34, a drive control unit 36, an acquisition unit 38, an analysis unit 40, and a calculation unit 42. The acquisition unit 38 acquires the detection results of the driving state detection sensor 12 and the object detection sensor 14. The acquisition unit 38 acquires destination and map information from the navigation device and acquires vehicle position information calculated using the Global Positioning Satellite System.

[0022] The analysis unit 40 recognizes information about an object, such as the object's position, based on the detection results of the object detection sensor 14. The analysis unit 40 may identify the object from the captured image using a neural network method, such as a deep learning method. The object may be an obstacle or a road installation. The analysis unit 40 recognizes the position of the preceding vehicle to be followed and the driving lane, and generates information about the driving target. The analysis unit 40 may set the target position and target yaw angle for automatic driving control.

[0023] The calculation unit 42 calculates target control values ​​to be executed in automatic driving control in order to reach the target position and target yaw angle, based on the acquisition results from the acquisition unit 38 and the analysis results from the analysis unit 40. The target control values ​​include target vehicle speed, target steering angle, and target deceleration.

[0024] When the vehicle behavior control device 16 performs roll control during steering, occupant comfort improves, but the turning characteristics change due to changes in suspension characteristics such as toe angle, camber angle, and lateral movement of the contact point. Furthermore, the amount of change in these turning characteristics is not constant and varies depending on the roll control gain. As a result, the ability of the automatic driving control to follow the target trajectory may change. In particular, when the vehicle control device 10 performs roll control during turning, the vehicle may turn too much and deviate from the target trajectory. Therefore, the vehicle control device 10 in this embodiment adjusts the target control value in the automatic driving control, especially the target steering angle, based on information indicating the roll control gain.

[0025] The communication unit 32 acquires information indicating the roll control gain from the roll control device 20. The estimation unit 34 estimates the turning characteristics of the vehicle according to the roll control gain. The turning characteristics estimated by the estimation unit 34 are based on the suspension characteristics and may be at least one of the equivalent cornering power of the wheels during roll control and the lateral force delay time constant.

[0026] Figure 2 shows the relationship between roll control gain and equivalent cornering power. The horizontal axis of Figure 2 represents the roll angle RA as the roll control gain, and the vertical axis represents the equivalent cornering power ratio CPr.

[0027] The roll angle RA is the roll angle RA (in [deg / G]) corresponding to the detected lateral acceleration, and may be the target control value of the vehicle behavior control device 16. A roll angle RA of zero represents a horizontal state, and increases as the vehicle body tilts outward during a turn. The outward tilt during a turn is sometimes called the positive roll angle.

[0028] The normal equivalent cornering power ratio of 44 is the ratio of the equivalent cornering power without roll control to the equivalent cornering power without roll control, and is 1. The equivalent cornering power ratio of 46 is the ratio of the equivalent cornering power with roll control to the equivalent cornering power without roll control.

[0029] The equivalent cornering power ratio 46 shows that the equivalent cornering power decreases as the roll angle RA increases. In other words, when control is applied to roll outwards during a turn, the equivalent cornering power decreases, and the grip of the wheels decreases. At the intersection of the equivalent cornering power ratio 44 and the equivalent cornering power ratio 46, there is no deviation in the equivalent cornering power due to roll control.

[0030] Information showing the relationship between the roll angle RA, which is the roll control gain, and the equivalent cornering power may be stored in advance in the driving control device 22. That is, the estimation unit 34 may estimate the equivalent cornering power of the vehicle behavior control device 16 according to the roll control gain based on a pre-stored two-dimensional map. This relationship is generated by conducting experiments for each vehicle type, etc. Alternatively, the estimation unit 34 may estimate the equivalent cornering power according to the roll control gain using a mathematical formula.

[0031] The relationship between roll control gain and equivalent cornering power shows that the equivalent cornering power decreases as the roll control gain tilts the vehicle body outward during a turn. This allows for accurate estimation of the equivalent cornering power as it changes in response to the roll control gain. However, if the suspension geometry and tire characteristics differ significantly from those of a typical vehicle, the relationship may not be limited to that shown in Figure 2.

[0032] Figure 3 shows the relationship between the roll control gain and the lateral force delay time constant. The horizontal axis in Figure 3 is the roll angle RA, as in Figure 2, and the vertical axis is the lateral force delay time constant ratio Tr. The lateral force delay time constant indicates the responsiveness of the lateral force generated on the wheel to the slip angle or steering angle.

[0033] The normal lateral force delay time constant ratio of 48 is the ratio of the lateral force delay time constant when roll control is not performed to the lateral force delay time constant when roll control is not performed, and is 1. The lateral force delay time constant ratio of 50 is the ratio of the lateral force delay time constant when roll control is performed to the lateral force delay time constant when roll control is not performed.

[0034] A lateral force delay time constant ratio of 50 indicates that the lateral force delay time constant increases as the roll angle RA increases. In other words, when control is performed to roll outwards during a turn, the lateral force delay time constant becomes larger than usual.

[0035] The estimation unit 34 estimates the lateral force delay time constant of the vehicle behavior control device 16 according to the roll control gain, based on information showing the relationship between the roll control gain and the lateral force delay time constant, which is stored in advance. The information showing the relationship between the roll control gain and the lateral force delay time constant may be stored in the driving control device 22 in the form of a mathematical formula or a map.

[0036] The relationship between roll control gain and lateral force delay time constant is that the lateral force delay time constant increases as the roll control gain tilts the vehicle body outward during a turn. This allows for accurate estimation of the lateral force delay time constant, which changes in accordance with the roll control gain.

[0037] The arithmetic unit 42 calculates a target control value to be executed in the automatic driving control based on the estimated turning characteristics of the vehicle. Specifically, it calculates a target steering angle to be executed in the automatic driving control based on the estimated equivalent cornering power ratio CPr and the lateral force delay time constant ratio Tr. The arithmetic unit 42 adjusts the target steering angle to be executed in the automatic driving control based on the roll control gain when the vehicle is turning and under roll control. This can improve the driver's comfort by roll control and also improve the tracking performance with respect to the target trajectory in the automatic driving control.

[0038] FIG. 4 is a diagram showing the turning state of the vehicle in a two-wheel model. In the two-wheel model in which the vehicle is simplified, the lateral force F of the front wheel , cr , cf , r , f , cf , f , cf ,

[0039] , pf , f , r , cf , pr , cf , f , cf , , and the lateral force F of the rear wheel r are calculated by the following equations (1) and (2). In the simplified two-wheel model, the center of gravity is located between one front wheel and one rear wheel. F f =C pf C cf (δ-β-rl f / V) / (1+T f T cf S) ··· Equation (1) C pf is the normal equivalent cornering power of the front wheel and is a value not corrected by C cf . C cf is the equivalent cornering power ratio of the front wheel according to the roll control gain. δ is the steering angle. β is the slip angle. r is the yaw angle at the center of gravity. l f is the distance from the center of gravity to the front wheel. V is the vehicle speed. T f is the normal lateral force delay time constant of the front wheel and is a value not corrected by T cf . T cf is the lateral force delay time constant ratio of the front wheel according to the roll control gain. S is a preset Laplace operator.

[0039] F r =C pr C cr (δ-β-rl r / V) / (1+T r T cr S)...Equation (2) C pr This is the normal equivalent cornering power of the rear wheel, C cr This is the value that has not been corrected by C. cr This is the equivalent cornering power ratio of the rear wheels according to the roll control gain. r is the lag time constant of the normal lateral force on the rear wheels, and T cr This is the value that has not been corrected by T. cr This is the ratio of the lag time constant of the lateral force on the rear wheels in accordance with the roll control gain.

[0040] Equations (1) and (2) calculate the lateral force of the wheel corrected by the equivalent cornering power ratio and the lateral force delay time constant ratio. In equations (1) and (2), it is also possible to correct using only one of the equivalent cornering power ratio or the lateral force delay time constant ratio.

[0041] By substituting the corrected lateral force of the wheels into the equations of motion (3), (4), and (5) below, the lateral acceleration y'' at the vehicle's center of gravity, the angular velocity r' of the yaw angle, and the angular velocity β' of the slip angle can be calculated. Therefore, the vehicle motion, including the effect of the roll control gain, can be estimated. y"=(2F f +2F r ) / M...Equation (3) r'=(2l f F f -2l r F r ) / I z ...Equation (4) β'=y" / Vr y is the lateral displacement of the center of gravity. M is the vehicle weight. Iz is the moment of inertia of the center of gravity. r is the yaw angle.

[0042] The calculation unit 42 corrects the target steering angle so that the predicted driving state based on the estimated turning characteristics matches the target position and target yaw angle set on the target trajectory, and calculates the corrected target steering angle. The calculation unit 42 takes the estimated turning characteristics, vehicle speed, and the target steering angle before correction as input and calculates the corrected target steering angle. This allows adjustment for turning deviations caused by roll control during autonomous driving. The drive control unit 36 ​​controls the driving device 18 according to the target control values ​​calculated by the calculation unit 42.

[0043] Figure 5 is a flowchart of the vehicle control method in the embodiment. The acquisition unit 24 of the roll control device 20 acquires driving state information, particularly the lateral acceleration of the vehicle body, from the driving state detection sensor 12 (S10). The gain calculation unit 26 calculates a roll control gain based on the lateral acceleration in order to suppress the movement of the vehicle body in the roll direction (S12). The communication unit 30 transmits the calculated roll control gain to the driving control device 22 (S14).

[0044] The estimation unit 34 of the driving control device 22 estimates the vehicle's turning characteristics, specifically the equivalent cornering power ratio and the lateral force delay time constant ratio, according to the acquired roll control gain (S16). The calculation unit 42 calculates the target steering angle to be executed in the automatic driving control based on the estimated turning characteristics (S18).

[0045] The present disclosure has been explained above based on the examples described. The present disclosure is not limited to the examples described above, and various modifications such as design changes can be made based on the knowledge of those skilled in the art.

[0046] In this embodiment, the estimation unit 34 is shown to be provided in the driving control device 22, but it is not limited to this embodiment and may be provided in the roll control device 20. In this embodiment, the roll control device 20 estimates the turning characteristics of the vehicle according to the roll control gain and transmits the estimated turning characteristics to the driving control device 22. [Explanation of Symbols]

[0047] 1 Vehicle control system, 10 Vehicle control device, 12 Driving state detection sensor, 14 Object detection sensor, 16 Vehicle behavior control device, 18 Driving device, 20 Roll control device, 22 Driving control device, 24 Acquisition unit, 26 Gain calculation unit, 28 Drive control unit, 30,32 Communication unit, 34 Estimation unit, 36 Drive control unit, 38 Acquisition unit, 40 Analysis unit, 42 Calculation unit.

Claims

1. A vehicle control device that controls a vehicle behavior control device capable of controlling the roll direction movement of the vehicle body, An acquisition unit that acquires information indicating the roll control gain for driving the vehicle behavior control device in order to move the vehicle body in the roll direction, A vehicle control device characterized by comprising: a calculation unit that calculates a target control value to be executed in the automatic driving control based on information indicating the roll control gain when automatic driving control is being performed.

2. The system further includes an estimation unit that estimates the turning characteristics of the vehicle according to the roll control gain, The vehicle control device according to claim 1, characterized in that the calculation unit calculates a target steering angle to be executed in automatic driving control based on the estimated turning characteristics.

3. The vehicle control device according to claim 2, characterized in that the estimation unit estimates at least one of the equivalent cornering power or lateral force delay time constant of the vehicle behavior control device with respect to the roll control gain as a turning characteristic.

4. The estimation unit estimates the equivalent cornering power of the vehicle behavior control device corresponding to the roll control gain, based on information held in advance that shows the relationship between the roll control gain and the equivalent cornering power. The vehicle control device according to claim 3, characterized in that the information showing the relationship between the roll control gain and the equivalent cornering power is such that the equivalent cornering power decreases as the amount by which the roll control gain tilts the vehicle body outward during a turn increases.

5. A vehicle control method performed by a vehicle control device that controls a vehicle behavior control device capable of controlling the roll direction movement of the vehicle body, The steps include: acquiring information indicating a roll control gain for driving the vehicle behavior control device to move the vehicle body in the roll direction; A vehicle control method characterized by including the step of calculating a target control value to be executed in the automated driving control based on the acquired roll control gain when automated driving control is being performed.

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