Vehicle control system

Abstract

To reduce a bother on a driver while simultaneously preventing invalidation of collision prevention brake control only by an operation for invalidating side-slipping prevention control and guaranteeing stability of a vehicle behavior during the collision prevention brake control.SOLUTION: A vehicle control system configured to be able to execute collision prevention brake control and side-slipping prevention control for a vehicle using a brake unit that brakes the vehicle performs a side-slipping prediction process for predicting whether the vehicle slips sideways during the execution of the collision prevention brake control on the basis of a reference vehicle behavior which is a behavior of the vehicle when the collision prevention brake control is started and a control value of the collision prevention brake control, and a validation process for validating the side-slipping prevention control if the side-slipping prevention control has been invalidated upon acquisition of a prediction result of the side-slipping prediction process indicating a side-slipping behavior.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a vehicle control system configured to be capable of performing collision avoidance braking control and skid prevention control for a vehicle using a braking unit that brakes the vehicle.

Background Art

[0002] As vehicle control, for example, collision avoidance braking control such as AEB (Autonomous Emergency Braking) and skid prevention control (ESC: Electronic Stability Control) are known. The collision avoidance braking control mentioned here means control for avoiding a collision of a vehicle using a braking unit such as a brake mechanism. It is a concept including all collision avoidance braking controls involving vehicle braking, and may include braking control involving steering avoidance such as AES (Automatic Emergency Steering) in addition to the above-mentioned AEB.

[0003] Collision avoidance braking control may perform sudden braking or sudden turning of the vehicle, which is not originally recommended. For the purpose of ensuring the stability of the vehicle behavior at this time, it is done that enabling the skid prevention control is one of the operating conditions of the collision avoidance braking control.

[0004] However, if enabling the skid prevention control as described above is set as one of the operating conditions of the collision avoidance braking control, the collision avoidance braking control will also be disabled only by an operation for disabling the skid prevention control, which is not desirable.

[0005] In the technique described in Patent Document 1 below, on the premise that the collision avoidance braking control is enabled even when the skid prevention control is disabled, a method is adopted in which the skid prevention control is enabled on the condition that the collision avoidance braking control is activated. Thereby, it is intended to ensure the stability of the vehicle behavior during the collision avoidance braking control. This can be rephrased as an attempt to prevent collision avoidance braking control from being disabled solely by an operation to disable anti-skid control, while simultaneously ensuring the stability of vehicle behavior during collision avoidance braking control. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2015-048006 [Overview of the project] [Problems that the invention aims to solve]

[0007] In the technology described in Patent Document 1, the anti-skid control is activated only on the condition that collision avoidance braking control has been activated. However, in that case, the anti-skid control would also be activated in response to malfunctions of the collision avoidance braking control, such as the collision avoidance braking control being activated unnecessarily. When the anti-skid control is activated in response to a malfunction of the collision avoidance braking control in this way, it may cause annoyance to the driver. For example, an unnecessary display indicating that the anti-skid control system is enabled may be shown, potentially causing annoyance to the driver. Furthermore, scenarios in which the driver may disable the anti-skid control include, for example, sports driving such as circuit driving. In such cases, if a malfunction occurs in the collision avoidance braking control, the anti-skid control may be unnecessarily activated, potentially worsening drivability during sports driving and causing annoyance to the driver.

[0008] This invention was made in view of the above circumstances, and aims to reduce driver inconvenience while simultaneously preventing collision avoidance braking control from being disabled by simply disabling the anti-skid control, and ensuring the stability of vehicle behavior during collision avoidance braking control. [Means for solving the problem]

[0009] The vehicle control system according to the present invention is a vehicle control system configured to perform collision avoidance braking control and anti-skid control for a vehicle using a braking unit that brakes the vehicle, comprising one or more processors and one or more storage media storing a program executed by the one or more processors, wherein the program includes one or more instructions, and the instructions cause the one or more processors to perform a skid prediction process, which is a prediction of whether or not the vehicle will skid during the execution of the collision avoidance braking control, based on a reference vehicle behavior, which is the behavior of the vehicle when the collision avoidance braking control is started, and a control value of the collision avoidance braking control, and to perform an activation process, which enables the anti-skid control if the anti-skid control is disabled, in response to the prediction result obtained by the skid prediction process that the vehicle will skid. According to the above configuration, even if the activation of yaw control is not included as an operating condition for collision avoidance braking control, in other words, even if collision avoidance braking control is not disabled solely by an operation to disable yaw control, yaw control can still be activated during collision avoidance braking control, thus ensuring the stability of vehicle behavior during collision avoidance braking control. Furthermore, according to the above configuration, it is possible to enable yaw control only when it is predicted that the vehicle will skid as a result of collision avoidance braking control, thus preventing yaw control from being activated even in the event of a malfunction that unnecessarily activates collision avoidance braking control. [Effects of the Invention]

[0010] According to the present invention, it is possible to prevent collision avoidance braking control from being disabled simply by disabling the anti-skid control, while simultaneously ensuring the stability of vehicle behavior during collision avoidance braking control, thereby reducing inconvenience for the driver. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows an overview of the configuration of a vehicle equipped with a vehicle control system as an embodiment. [Figure 2] This is an explanatory diagram illustrating an example of the configuration of the main components of a vehicle control system as an embodiment. [Figure 3] This flowchart shows a specific example of collision avoidance control in the embodiment. [Figure 4] This is a functional block diagram showing the functions of an embodiment of the predictive control unit. [Figure 5] This is an explanatory diagram illustrating the prediction of future deceleration and the prediction of lateral slip using a threshold in the embodiment. [Figure 6] This flowchart shows a specific example of a processing procedure for realizing behavior stabilization control as an embodiment. [Modes for carrying out the invention]

[0012] <1.Device configuration> Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 is a diagram showing the general configuration of a vehicle 100 equipped with a vehicle control system 1 as an embodiment of the present invention, and Figure 2 is an explanatory diagram of an example configuration of the main parts of the vehicle control system 1 as an embodiment. In addition to the example configuration of the vehicle control system 1, Figure 2 also shows an example configuration of the steering mechanism 30 that the vehicle 100 has.

[0013] In this embodiment, the vehicle 100 is configured as, for example, a four-wheeled automobile and has at least one of an engine and a drive motor as the drive source for the wheels. In other words, the vehicle 100 can be configured as an EV (Electric Vehicle) having only a drive motor among the engine and drive motor as the drive source for the wheels, an HEV (Hybrid Electric Vehicle) having both an engine and a drive motor, or an engine-powered vehicle having only an engine.

[0014] The vehicle 100 includes a braking unit (not shown) for braking the vehicle 100 and a steering unit (steering mechanism 30 described later) for enabling the vehicle to turn freely. The braking unit mentioned here broadly means a configuration that not only includes a brake mechanism such as a disk brake or a drum brake, but also performs vehicle braking by means of regenerative braking by a driving motor in the case of being configured as an EV vehicle or an HEV vehicle. Also, as the steering unit, it broadly means a configuration such as the steering mechanism 30 for enabling the vehicle to turn freely in the left - right direction.

[0015] The vehicle 100 also has a function of recognizing the vehicle external environment. Specifically, the vehicle 100 in this example has a function of recognizing the vehicle external environment by including an imaging unit 10 described later.

[0016] As shown in FIG. 1, the vehicle control system 1 provided in the vehicle 100 includes a predictive control unit 15 that performs control according to the present invention. The vehicle control system 1 also includes a driving assistance control unit 13 that performs various controls for driving assistance, and a collision avoidance control unit 14 is provided in the driving assistance control unit 13. As will be described later, the collision avoidance control unit 14 performs collision avoidance braking control for the vehicle 100. The collision avoidance braking control mentioned here means a control for attempting to avoid a collision of the vehicle using a braking unit such as a brake mechanism. It is a concept that includes all collision avoidance controls involving vehicle braking, including, for example, AEB (Autonomous Emergency Braking: collision damage mitigation brake), and also includes braking control involving steering avoidance such as AES (Automatic Emergency Steering).

[0017] In addition, the vehicle control system 1 is provided with an ESC (Electronic Stability Control) unit 25. The ESC (anti-skid control) mentioned here means a control that aims to maintain a stable posture of the vehicle during turning without skidding by controlling the braking unit and engine output (including motor output control in the case of a vehicle having a driving motor).

[0018] In FIG. 2, the vehicle control system 1 is provided with a vehicle speed sensor 16, a motion sensor 17, an actual steering angle sensor 18, and a steering torque sensor 19 as sensors related to collision avoidance control. Furthermore, a display unit 23 and a sound output unit 24 are provided as related parts of collision avoidance control.

[0019] The vehicle speed sensor 16 is a sensor that detects the speed of the vehicle 100 as the own vehicle speed v. The motion sensor 17 comprehensively represents sensors such as a yaw rate sensor and an acceleration sensor that detect the motion of the vehicle.

[0020] The actual steering angle sensor 18 detects the actual steering angle (for example, the angle formed with the longitudinal axis of the vehicle 100) of the steering wheels 40 (the left and right steering wheels 40L and 40R described later) as the actual steering angle. The steering torque sensor 19 detects the steering force (steering input torque) input by the driver via the steering wheel 34 by detecting, for example, the input torque with respect to the steering shaft 32.

[0021] The imaging unit 10 includes an imaging unit 11L, an imaging unit 11R installed in the vehicle 100 so as to be able to image the traveling direction (front), an image processing unit 12, and a driving support control unit 13. The vehicle speed sensor 16, the motion sensor 17, and the actual steering angle sensor 18 are connected to the imaging unit 10, and the image processing unit 12, the driving support control unit 13, and the prediction control unit 15 provided in the imaging unit 10 are capable of inputting detection signals from these sensors.

[0022] Furthermore, an operation unit 26 is connected to the imaging unit 10 to receive operation input from the driver or other occupants of the vehicle 100. This enables the image processing unit 12, the driving support control unit 13, and the predictive control unit 15 to perform processing in accordance with the operation input information from the driver or other occupants via the operation unit 26.

[0023] The imaging units 11L and 11R are positioned, for example, near the top of the windshield of the vehicle 100, at a predetermined distance in the vehicle width direction, to enable distance measurement using the so-called stereo method. The optical axes of the imaging units 11L and 11R are parallel, and their focal lengths are the same. In addition, their frame periods are synchronized, and their frame rates are also the same.

[0024] The electrical signals (image signals) obtained from the image sensors 11L and 11R are each converted using A / D (Analog to Digital) conversion to form digital image signals (image data) that represent brightness values ​​with predetermined gradations on a pixel-by-pixel basis. The image data is, for example, color image data.

[0025] The image processing unit 12 is configured with a microcomputer equipped with, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory) as a work area, and the CPU executes various processes according to the program stored in the ROM. The image processing unit 12 stores the image data of each frame, which is the image data obtained by the imaging units 11L and 11R from imaging the area in front of the vehicle 100, into its internal memory. Based on the two image data of each frame, it then performs processing to recognize the external environment, specifically, various processing to recognize objects present in front of the vehicle 100. For example, it recognizes regulatory lines (such as white or orange lines) formed on the road, as well as preceding vehicles, pedestrians, obstacles, and various three-dimensional objects such as guardrails, curbs, and side walls along the road. Here, the restricted line refers to the line that separates the vehicle's driving lane. The image processing unit 12 recognizes the vehicle's driving lane (own lane) based on the information of the recognized restricted line.

[0026] The image processing unit 12, in recognizing three-dimensional objects in front of the vehicle 100, processes a pair of captured image data (stereo images) obtained by the imaging units 11L and 11R to determine distance information using the principle of triangulation from the amount of displacement (i.e., parallax) between corresponding positions in the images, and generates data (distance image) representing a three-dimensional distance distribution based on this distance information. Then, based on this distance image, it performs known grouping processing, etc., to recognize three-dimensional objects such as the aforementioned restricted lines, guardrails, curbs, side walls, pedestrians, and vehicles.

[0027] Furthermore, the image processing unit 12 stores the position of the recognized three-dimensional object as coordinate information of the three-dimensional object, where the z-axis represents the front-to-back direction of the vehicle 100 and the x-axis represents the left-to-right direction (lateral direction) of the vehicle 100. Specifically, in this example, the image processing unit 12 stores information on the positions of the left and right endpoints of the rear surface of the three-dimensional object, especially for preceding vehicles, pedestrians, obstacles, etc. Furthermore, it stores the center position of these left and right endpoints on the rear surface as information on the center position of the three-dimensional object.

[0028] Furthermore, the image processing unit 12 also calculates and stores information about the recognized object, including the vertical distance of the object (distance from the object in the z-axis direction: hereinafter referred to as "object vertical distance dz"), the relative vertical velocity of the object (the rate of change of the object vertical distance dz per unit time: hereinafter referred to as "relative vertical velocity vrz"), the vertical velocity of the object ("relative vertical velocity vrz" + "vehicle speed v": hereinafter referred to as "vertical velocity vz"), and the vertical acceleration of the object (the derivative of vertical velocity vz: hereinafter referred to as "vertical acceleration az"). Furthermore, the image processing unit 12 also calculates and stores information about the recognized three-dimensional object, including the horizontal distance of the three-dimensional object (distance from the three-dimensional object in the x-axis direction: hereinafter referred to as "horizontal distance dx"), the horizontal relative velocity of the three-dimensional object (the rate of change of the horizontal distance dx per unit time: hereinafter referred to as "horizontal relative velocity vrx"), the horizontal velocity of the three-dimensional object ("horizontal relative velocity vrx" + "horizontal movement speed of the vehicle 100": hereinafter referred to as "horizontal velocity vx"), and the horizontal acceleration of the three-dimensional object (the derivative of horizontal velocity vx: hereinafter referred to as "horizontal acceleration ax").

[0029] The image processing unit 12 recognizes, among the recognized three-dimensional objects as vehicles, the vehicle closest to the vehicle in its own lane and facing approximately the same direction as vehicle 100 as the preceding vehicle. Vehicles with a speed of approximately 0 km / h among the preceding vehicles are recognized as stationary preceding vehicles.

[0030] The image recognition results obtained by the image processing unit 12, such as information on the position, velocity, and acceleration of three-dimensional objects, as well as information on the vehicle's lane, are used for various driving assistance control functions.

[0031] The driver assistance control unit 13 performs various driver assistance controls based on the image recognition result information from the image processing unit 12. The driver assistance control unit 13 includes a collision avoidance control unit 14. The collision avoidance control unit 14 is configured with a microcomputer, for example, a CPU, ROM, and RAM, and performs various processes according to a program stored in the ROM. Specifically, the collision avoidance control unit 14 performs processing related to AEB (Autonomous Emergency Braking) and AES (Automatic Emergency Steering). In collision avoidance control as AEB or AES, a risk assessment value representing the magnitude of the risk of collision with an object is calculated based on the recognition results of the external environment, and the timing of braking or steering intervention is determined based on the magnitude of the risk indicated by the risk assessment value. Specifically, the collision avoidance control unit 14 in this example calculates a risk assessment value as TTC (Time To Collision) for each object recognized by the image processing unit 12, based on the information of the object's vertical distance dz and vertical relative velocity vrz described above. Here, TTC is an indicator that shows how many seconds remain until a collision if the current vertical relative velocity vrz is maintained, and is specifically calculated by, for example, the following formula. TTC=dz / vrz Such TTC values ​​represent a risk assessment indicator where a smaller value indicates a greater risk of collision.

[0032] Based on the TTC values ​​described above, the collision avoidance control unit 14 determines whether or not a collision prediction object exists for a target object that is a specific type of three-dimensional object among the three-dimensional objects recognized by the image processing unit 12. Here, a collision prediction object refers to an object that is predicted to collide with the vehicle 100. In this example, the "specific type of target object" refers to three-dimensional objects that include moving living beings such as people and animals (hereinafter referred to as "animals"). Specifically in this example, it refers to three-dimensional objects that include animals, excluding those recognized as preceding vehicles. Therefore, the three-dimensional objects that are targets for collision avoidance also include the aforementioned guardrails, curbs, and side walls.

[0033] The presence or absence of a collision prediction object is determined based on the TTC, for example, as follows: In other words, the system determines whether there are any three-dimensional objects that fall under the category of "specific types of target objects" that have a lateral overlap ratio with the vehicle 100 of a predetermined value or more and whose TTC is below a predetermined threshold. If no such objects exist, the collision avoidance control unit 14 determines that there are no collision prediction objects. Furthermore, if the above determination reveals only one object matching the criteria, that object is designated as the collision prediction object. If there are multiple matching objects, for example, the object with the smallest TTC value among them is designated as the collision prediction object.

[0034] If a collision prediction object is present, the collision avoidance control unit 14 performs AEB on the collision prediction object and, if necessary, performs AES. Specifically, it first starts only AEB, and if it determines that a collision cannot be avoided with AEB alone, it continues braking with AEB while performing steering intervention with AES to avoid the collision.

[0035] In the imaging unit 10, the predictive control unit 15 is configured with a microcomputer equipped with, for example, a CPU, ROM, and RAM, and performs various processes according to a program stored in the ROM. The predictive control unit 15 performs processes such as predicting skids as part of this embodiment, and activating the ESC based on the skid prediction results. The specific details of these processes as part of this embodiment will be explained separately.

[0036] The vehicle control system 1 includes a brake control unit 20 and brake-related actuators 21 as components for realizing braking control of the vehicle 100. The brake control unit 20 is configured with a microcomputer and controls various actuators provided as brake-related actuators 21 based on instructions from the driver assistance control unit 13 (including the collision avoidance control unit 14). The brake-related actuators 21 include various brake-related actuators such as hydraulic control actuators for controlling the output hydraulic pressure from the brake booster to the master cylinder and the hydraulic pressure in the brake fluid piping. The brake control unit 20 controls the hydraulic control actuators based on instructions from the driver assistance control unit 13 to control the braking of the vehicle 100.

[0037] When the AEB is activated, the collision avoidance control unit 14 brakes the vehicle 100 by issuing a braking command to the brake control unit 20.

[0038] Furthermore, when the AES is activated, the collision avoidance control unit 14 determines the target steering angle based on the image recognition results from the image processing unit 12. It then outputs a steering instruction current value corresponding to this target steering angle to the EPS (Electric Power Steering) control unit 22, which will be described later.

[0039] The ESC unit 25 is a control unit for implementing anti-skid control. It is configured with a microcomputer, for example, equipped with a CPU, ROM, and RAM, and implements anti-skid control by executing various processes according to a program stored in the ROM. In this example, the ESC unit 25 is equipped with various sensors used for anti-skid control, specifically, wheel speed sensors and yaw rate sensors, and the CPU of the ESC unit 25 controls the brake control unit 20 based on the detection information from these sensors to achieve anti-skid control.

[0040] An operating unit 26 is connected to the ESC unit 25. In this example, for the vehicle 100, it is possible to enable and disable the anti-skid control provided by the ESC unit 25 using the operating unit 26. The ESC unit 25 has the function of enabling and disabling the anti-skid control in accordance with the operation.

[0041] Herein, in this specification, enabling a control means putting the control into an executable state (a state in which execution is permitted). Disabling a control means putting the control into an executable state (a state in which execution is not permitted).

[0042] The driver assistance control unit 13 also provides the driver with various notifications regarding driver assistance. Specifically, the driver assistance control unit 13 supplies display information and sound instruction information to the display unit 23 and the sound unit 24. The display unit 23 comprehensively represents, for example, a display control unit and display device, such as a microcomputer. The display device includes, for example, various meters such as a speedometer and tachometer, an MFD (Multi Function Display), and other devices for presenting information to the driver, which are installed in the instrument panel in front of the driver. Regarding collision avoidance control, the display unit 23 displays warnings related to the risk of collision with an object, and displays to make the driver aware of the operation / deactivation of AEB and AES. In addition, the display unit 23 is capable of displaying at least one of the following: that the anti-skid control by the ESC unit 25 is enabled or disabled.

[0043] The sound generation unit 24 comprehensively represents, for example, a sound generation control unit using a microcomputer and sound generation devices such as an amplifier / speaker. In relation to collision avoidance control, the sound generation unit 24 outputs warning sounds and notification sounds to make the driver aware of the activation / deactivation of AEB and AES.

[0044] The EPS control unit 22 is configured, for example, with a microcomputer, and controls the EPS motor 42 in the steering mechanism 30 based on the steering instruction current value from the driver assistance control unit 13 (collision avoidance control unit 14) and the detection signal from the steering torque sensor 19.

[0045] The EPS control unit 22 determines a steering instruction current value to obtain steering assist torque corresponding to the steering input torque obtained from the steering torque sensor 19, based on the information of the steering input torque by the driver, and drives the EPS motor 42 based on this instruction current value. This realizes power steering control that assists the driver's steering. In addition, the driver is allowed to perform steering operations even when the collision avoidance control unit 14 is performing steering control. When manual steering is performed during steering control in this manner, the EPS control unit 22 adds up the steering instruction current value from the collision avoidance control unit 14 and the steering instruction current value for power steering control obtained as described above, and drives the EPS motor 42 based on the added current value.

[0046] The steering mechanism 30, which is subject to steering control, is configured as follows, for example. The steering mechanism 30 has a steering shaft 32 that is rotatably supported on a vehicle frame (not shown) via a steering column 33. One end of the steering shaft 32 extends towards the driver's seat, and a steering wheel 34 is attached to this end. A pinion shaft 35 is connected to the other end of the steering shaft 32. The pinion (not shown) on the pinion shaft 35 meshes with a rack provided on a rack shaft 37, which is inserted and supported in the steering gearbox 36 so as to be able to move back and forth. This constitutes a rack-and-pinion type steering gear mechanism.

[0047] Furthermore, both the left and right ends of the rack shaft 37 protrude from the steering gearbox 36, and tie rods 38 are connected to each of these left and right ends. Each tie rod 38 has a front knuckle 39 connected to the end opposite to the end connected to the rack shaft 37. Each front knuckle 39 supports the corresponding steering wheel 40 of the steering wheels 40L and 40R, and is also supported by the vehicle frame via a kingpin (not shown). Each front knuckle 39 is connected to the end of the corresponding tie rod 38 so as to be rotatable around the kingpin. Therefore, when the steering wheel 34 is operated and the steering shaft 32 and pinion shaft 35 are rotated, the rotation of the pinion shaft 35 causes the rack shaft 37 to move left and right, and this movement causes the front knuckle 39 to rotate around the kingpin, thereby turning the steering wheels 40L and 40R left and right.

[0048] Furthermore, an EPS motor 42 is connected to the pinion shaft 35 via an assist transmission mechanism 41. This EPS motor 42 assists the steering torque applied to the steering wheel 34 and adds steering torque to achieve the target steering angle.

[0049] <2. Regarding collision avoidance braking control> Here, as described above, in the vehicle control system 1 of this embodiment, if a collision prediction object is detected, AEB control is performed, and if it is determined that a collision cannot be avoided by braking the vehicle 100 with AEB alone, steering intervention is performed with AES. For confirmation, a specific example of this collision avoidance control process will be explained using the flowchart in Figure 3.

[0050] As shown in Figure 3, the collision avoidance control unit 14 first determines in step S11 whether or not it has detected a collision prediction object. That is, using the method described above, it determines whether or not there is a three-dimensional object among the three-dimensional objects recognized by the image processing unit 12 that satisfies the aforementioned overlap rate and TTC conditions, and if there is a three-dimensional object that satisfies these conditions, it obtains a determination result that a collision prediction object has been detected. As explained above, if there are multiple three-dimensional objects that satisfy these conditions, one three-dimensional object is determined to be the collision prediction object based on the TTC value.

[0051] In step S12, following step S11, the collision avoidance control unit 14 initiates brake intervention. That is, it initiates AEB control. Specifically, it issues instructions to the brake control unit 20 to initiate braking of the vehicle 100 using AEB.

[0052] In step S13, following step S12, the collision avoidance control unit 14 determines whether collision avoidance is possible using only the brakes. This determination process can be implemented, for example, by known methods. For example, it can be performed based on the current longitudinal relative velocity vrz of the collision prediction object and map information showing the TTC values ​​for which collision avoidance is possible for each longitudinal relative velocity vrz.

[0053] In step S13, if it is determined that collision avoidance is possible using only the brakes, the collision avoidance control unit 14 completes the series of processes shown in Figure 3. In other words, in this case, collision avoidance is attempted using only AEB (Automatic Emergency Braking).

[0054] On the other hand, if in step S13 it is determined that collision avoidance is not possible with braking alone, the collision avoidance control unit 14 proceeds to step S14 and calculates a target steering angle for collision avoidance. That is, it calculates a target steering angle to avoid a collision with the object recognized as a collision prediction object.

[0055] In response to the calculation of the target steering angle in step S14, the collision avoidance control unit 14 proceeds to step S15 and begins steering intervention, that is, it starts controlling the AES. Specifically, it instructs the EPS control unit 22 to set a target steering angle for collision avoidance and initiates steering intervention for collision avoidance.

[0056] In response to the process of initiating steering intervention in step S15, the collision avoidance control unit 14 completes the series of processes shown in Figure 3.

[0057] <3. Behavior stabilization control as an embodiment> In this case, it is desirable to disable the anti-skid control provided by the ESC unit 25. For example, it is desirable to be able to disable it during sports driving such as circuit driving, or when escaping from muddy or snowy roads. For this reason, it is effective to configure the vehicle control system 1 in this example so that the anti-skid control can be enabled or disabled by operation.

[0058] On the other hand, as mentioned above, collision avoidance braking control systems such as AEB may perform sudden braking or sharp turns of the vehicle, which are not recommended. Therefore, it is conceivable that enabling yaw control be one of the operating conditions for collision avoidance braking control in order to ensure the stability of the vehicle's behavior. However, in that case, simply disabling yaw control would also disable collision avoidance braking control, which is undesirable.

[0059] Therefore, in order to prevent collision avoidance braking control from being disabled solely by an operation to disable yaw control, and to ensure the stability of vehicle behavior during collision avoidance braking control, it is conceivable that yaw control be enabled in response to the activation of collision avoidance braking control when yaw control is disabled (see Patent Document 1 mentioned above).

[0060] However, if the anti-skid control is activated solely on the condition that collision avoidance braking control is activated, then the anti-skid control will also be activated in cases of malfunction of collision avoidance braking control, such as when collision avoidance braking control is activated unnecessarily, which may cause annoyance to the driver.

[0061] Therefore, in this embodiment, in order to prevent collision avoidance braking control from being disabled by simply disabling the anti-skid control, and to ensure the stability of vehicle behavior during collision avoidance braking control, while reducing driver inconvenience, the predictive control unit 15 performs the following control.

[0062] Figure 4 is a functional block diagram showing the functions of the predictive control unit 15 as an embodiment. As shown in the figure, the predictive control unit 15 has the functions of a predictive processing unit F1, an activation processing unit F2, and a post-activation processing unit F3.

[0063] The prediction processing unit F1 performs a sideslip prediction, which is a prediction of whether or not the vehicle 100 will exhibit sideslip behavior during the execution of collision avoidance braking control, based on the reference vehicle behavior, which is the behavior of the vehicle 100 when collision avoidance braking control is initiated, and the control value of the collision avoidance braking control.

[0064] If the sideslip prediction processing unit F1 predicts that sideslip behavior will occur, the activation processing unit F2 will activate the sideslip prevention control if it has been disabled.

[0065] By having these prediction processing unit F1 and activation processing unit F2, even if the activation of yaw control is not included as an operating condition for collision avoidance braking control, in other words, even if collision avoidance braking control is not disabled solely by an operation to disable yaw control, yaw control can still be activated during collision avoidance braking control, thus ensuring the stability of vehicle behavior during collision avoidance braking control. Furthermore, since yaw control can be activated only when it is predicted that the vehicle will skid as a result of collision avoidance braking control, it is possible to prevent yaw control from being activated even if a malfunction occurs that unnecessarily activates collision avoidance braking control.

[0066] In this example, the prediction processing unit F1 performs lateral slip prediction based on the response characteristics of the braking unit to braking control. In braking control, a time lag may occur between the time a braking control value is output and the time when a braking force corresponding to that control value is actually generated as a response. When the braking unit is composed of a brake mechanism, this manifests as a response time lag, for example, between the time a hydraulic pressure control value is output and the time when hydraulic pressure corresponding to that control value is actually generated in the brake caliper. By performing skid prediction that takes into account the response characteristics of such a control unit, skid prevention control can be activated at the appropriate timing, thereby improving the stability of vehicle behavior during collision avoidance braking control.

[0067] This section explains a specific example of lateral slip prediction performed by the prediction processing unit F1. First, the prediction processing unit F1 estimates the behavior of vehicle 100 in response to the commencement of collision avoidance braking control. This can be rephrased as the estimation of the reference vehicle behavior described above. The vehicle behavior estimated here includes, for example, whether vehicle 100 is turning or traveling straight, and at what speed it is traveling, which serve as criteria for determining whether vehicle 100 is exhibiting a sideslip behavior. Specifically, the vehicle behavior that serves as criteria for determining whether vehicle 100 is exhibiting a sideslip behavior is estimated based on information that can be detected by the motion sensor 17, such as the yaw rate and acceleration in the front, rear, left, and right directions of vehicle 100, as well as vehicle speed information detected by the vehicle speed sensor 16 and actual steering angle information detected by the actual steering angle sensor 18.

[0068] Then, the prediction processing unit F1 obtains a deceleration threshold THr based on the estimated reference vehicle behavior. This threshold THr represents the deceleration threshold at which a skid occurs when the vehicle 100 is behaving like a standard vehicle. In other words, it is a threshold that should be defined so that, when the vehicle 100 is behaving like a standard vehicle, it can be estimated that the vehicle 100 will exhibit a skid behavior when the deceleration exceeds the threshold THr. One method for obtaining a threshold value THr based on reference vehicle behavior is to use a table that shows the correspondence between reference vehicle behavior and the threshold value THr. In this case, a corresponding threshold value THr is determined for each type of reference vehicle behavior, for example, based on the results of experiments or simulations, and a table is created that shows the correspondence between these types of reference vehicle behavior and the threshold value THr. This table is stored in a memory device that can be read by the CPU of the predictive control unit 15, such as the ROM of the predictive control unit 15, so that the corresponding threshold value THr can be obtained based on the table and the reference vehicle behavior.

[0069] After obtaining a threshold THr based on the behavior of a reference vehicle, the prediction processing unit F1 predicts future deceleration based on the control value calculated by collision avoidance braking control and the response characteristics of the braking unit, and performs a sideslip prediction based on the comparison result between the predicted deceleration and the threshold THr.

[0070] Referring to Figure 5, we will explain the prediction of future deceleration and the prediction of lateral slip using the threshold THr. In Figure 5, the horizontal axis represents time t, and the vertical axis represents deceleration (m / s^2: "^" represents exponentiation). In the figure, points (circles) with "S" at the beginning of the symbol represent the control value output by collision avoidance braking control as deceleration. Here, the control value output by the collision avoidance control unit 14 through collision avoidance braking control is not limited to the deceleration value itself, but may also be a value other than deceleration, such as the brake fluid pressure value. Deceleration values ​​with "S" at the beginning of the symbol (hereinafter referred to as "deceleration S") represent such control values ​​as deceleration. Regarding the deceleration S, "Sb" represents the deceleration S corresponding to the control value output in the current processing cycle (t=T), and "Sa" represents the deceleration S corresponding to the control value output in the previous processing cycle (t=T-1).

[0071] Furthermore, in the figure, points with "E" at the beginning of the symbol represent the predicted deceleration (hereinafter referred to as "predicted deceleration E") based on the control value output by the collision avoidance braking control and the response characteristics of the braking unit. Specifically, the predicted deceleration E represented by "Eb" represents the predicted deceleration E predicted based on the control value of the collision avoidance braking control output in processing cycle T-1 and the response characteristics of the braking unit, while the predicted deceleration E represented by "Ea" represents the predicted deceleration E predicted based on the control value of the collision avoidance braking control output in the processing cycle immediately preceding processing cycle T-1 and the response characteristics of the braking unit.

[0072] Here, if the response characteristics of the braking unit are known, the curve of the predicted deceleration E, represented by the thick line in the figure, in other words, the information of the trajectory of the change in the predicted deceleration E with respect to time, can be appropriately predicted based on the response characteristics and the control value of the collision avoidance braking control. Therefore, the prediction processing unit F1 predicts future deceleration based on the control value of the collision avoidance braking control output for each processing cycle and the information indicating the response characteristics of the braking unit that has been stored in advance. In the figure, the curve of the predicted deceleration E shown by the thick dotted line represents the curve of the predicted deceleration E predicted at the timing of processing cycle T.

[0073] In this example, the prediction processing unit F1 predicts whether the vehicle 100 will exhibit a sideslip behavior based on the predicted deceleration curve E and the threshold THr, as described above. Specifically, it determines whether the predicted deceleration E exceeds the threshold THr in the predicted deceleration curve E. If the predicted deceleration E is determined to exceed the threshold Thr, the prediction processing unit F1 obtains a prediction result that the vehicle 100 will exhibit a sideslip behavior. If the predicted deceleration E is determined not to exceed the threshold Thr, the prediction processing unit F1 obtains a prediction result that the vehicle 100 will not exhibit a sideslip behavior.

[0074] For example, the above method can be used to predict the skid of vehicle 100 after collision avoidance braking control such as AEB has started. It should be noted that the method described above is merely one example, and various specific methods for predicting lateral slip are possible; it is not limited to any particular method. For example, in predicting skids, it is conceivable to use information on the road surface coefficient (μ). The road surface coefficient can be estimated, for example, based on image analysis of images captured by the imaging unit (at least one of 11L or 11R) or the slip ratio of the wheels. Furthermore, it is conceivable that temperature (outside temperature) information could be used in predicting lateral slip.

[0075] In Figure 4, the activation processing unit F2, in response to the prediction result obtained by the skid prediction processing unit F1 that skid behavior will occur, instructs the ESC unit 25 to activate the skid prevention control if the skid prevention control is disabled. As a result, after collision avoidance braking control such as AEB is initiated by the collision avoidance control unit 14, if the vehicle 100 is predicted to exhibit a skidding behavior based on the skidding prediction, the skidding prevention control by the ESC unit 25 is activated. Therefore, the behavior of the vehicle 1000 can be stabilized during collision avoidance braking control.

[0076] The post-activation processing unit F3 performs processing related to disabling the anti-skid control after the anti-skid control has been activated by the activation processing unit F2. In this example, the post-activation processing unit F3 performs a first post-activation process to disable the anti-skid control based on the estimated behavior of the vehicle 100 after the anti-skid control has been activated by the activation process. Specifically, after the anti-skid control is activated, the post-activation processing unit F3 in this example estimates the behavior of the vehicle 100 based on information such as acceleration and yaw rate detected by the motion sensor 17, vehicle speed detected by the vehicle speed sensor 16, and actual steering angle detected by the actual steering angle sensor 18. Specifically, it estimates whether the behavior of the vehicle 100 has stabilized. Here, "stabilized behavior" means that the vehicle 100 has entered a state where it is unlikely to exhibit skidding behavior. If it is estimated that the behavior of vehicle 100 has stabilized, the post-activation processing unit F3 instructs the ESC unit 25 to disable the anti-skid control. As a result, if the anti-skid control is disabled and then enabled by the activation processing unit F2, the anti-skid control can be returned to the disabled state in accordance with the estimation that the behavior of the vehicle 100 has stabilized.

[0077] <4. Processing Procedure> Referring to the flowchart in Figure 6, a specific example of a processing procedure for realizing the behavior stabilization control as described above will be explained. The process shown in Figure 6 is executed by the CPU of the predictive control unit 15 according to a program stored in a storage medium such as a ROM provided by the predictive control unit 15.

[0078] First, in step S101, the predictive control unit 15 waits for the start of collision avoidance braking control. That is, it waits for the start of collision avoidance braking control by the collision avoidance control unit 14 (in this example, the start of AEB: see S12 in Figure 3).

[0079] In step S102, following step S101, the predictive control unit 15 estimates the current vehicle behavior. This can be rephrased as the estimation of the reference vehicle behavior described above. Since an example of the reference vehicle behavior estimation method has already been explained, a redundant explanation will be avoided.

[0080] In step S103, following step S102, the predictive control unit 15 obtains a deceleration threshold THr based on the current vehicle behavior. As mentioned above, in this example, the threshold THr corresponding to the estimated vehicle behavior is obtained based on a table showing the correspondence between the type of vehicle behavior and the threshold THr.

[0081] In step S104, following step S103, the predictive control unit 15 predicts future deceleration based on the control value of the collision avoidance braking control and the response characteristics of the braking unit. That is, for example, the method described with reference to Figure 5 above predicts future deceleration based on the control value of the collision avoidance braking control and the response characteristics of the braking unit.

[0082] In step S105, following step S104, the predictive control unit 15 determines whether the predicted deceleration exceeds the threshold Thr. This corresponds to the aforementioned sideslip prediction, and in this example, it determines whether the predicted deceleration E exceeds the threshold Thr in the curve of the predicted deceleration E described above.

[0083] In step S105, if it is determined that the predicted deceleration does not exceed the threshold THr, the predictive control unit 15 returns to step S104. This makes it possible to repeatedly perform, in each processing cycle, the prediction of the future deceleration degree based on the control value and response characteristics of the collision avoidance braking control (S104), and the prediction of skid based on the predicted deceleration and the threshold THr (S105).

[0084] On the other hand, if in step S105 the predicted deceleration is determined to exceed the threshold Thr, the predictive control unit 15 proceeds to step S106 to determine whether or not the anti-skid control is disabled. If it is disabled, the status flag is turned ON in step S107, and then the unit proceeds to step S108 to enable the anti-skid control. In other words, the unit instructs the ESC unit 25 to enable the anti-skid control. After executing the activation process in step S108, the predictive control unit 15 proceeds to step S109.

[0085] Here, the status flag indicates whether or not the anti-skid control was disabled at the start of collision avoidance braking control. A status flag of ON indicates that it was disabled, and its initial value is OFF.

[0086] On the other hand, if step S106 determines that the anti-skid control was not disabled, the predictive control unit 15 skips steps S107 and S108 and proceeds to step S109.

[0087] In step S109, the predictive control unit 15 determines whether the status flag is ON or OFF. If the status flag is ON, the predictive control unit 15 proceeds to step S110 and waits until the vehicle behavior stabilizes through control. That is, it continues to estimate whether the behavior of the vehicle 100 has stabilized, as described above, until it obtains an estimation result that the behavior of the vehicle 100 has stabilized.

[0088] In step S110, if the predictive control unit 15 estimates that the vehicle behavior has stabilized, it proceeds to step S111 and disables the anti-skid control. Then, in step S112 following step S111, the predictive control unit 15 turns the status flag OFF and completes the series of processes shown in Figure 6.

[0089] Furthermore, if the predictive control unit 15 determines in step S109 that the status flag is not ON, it completes the example processing shown in Figure 6. That is, if the anti-skid control was enabled at the start of collision avoidance braking control, the anti-skid control remains enabled throughout the collision avoidance braking control.

[0090] <5. Variation> Although embodiments of the present invention have been described above, the present invention is not limited to the specific examples described above, and various modified configurations can be adopted. For example, in the above description, the post-activation processing unit F3 performs a first post-activation process that disables the anti-skid control in accordance with the estimation that the behavior of the vehicle 100 has stabilized after the anti-skid control has been activated. However, as an alternative second post-activation process, it is also conceivable that the anti-skid control may be maintained in an enabled state after the anti-skid control has been activated until an operation input is made to instruct the disabling of the anti-skid control. If a skid is predicted during collision avoidance braking control, it is estimated that, based on the road surface conditions while vehicle 100 is traveling, there is a high probability that a skid will occur again if collision avoidance braking control intervenes again. Therefore, by maintaining the effective state of the anti-skid control even after it has been activated as described above, the stability of the vehicle's behavior can be improved.

[0091] Furthermore, it is also conceivable that the disabling of the anti-skid control by the post-activation processing unit F3 should be performed in response to the completion of collision avoidance braking control. Alternatively, it is possible to disable the anti-skid control after the activation process according to the user's prior settings ("return to disabled state / continue enabled state" setting).

[0092] Furthermore, while the above explanation cited an example of performing external environment recognition processing related to collision avoidance braking control based on images captured by a camera, this external environment recognition processing can also be performed using, for example, radar or a map locator (recognition of objects near the vehicle based on a position sensor that detects the vehicle's position and high-precision map information).

[0093] <6. Summary of Embodiments> As described above, the vehicle control system (1) as an embodiment is a vehicle control system configured to perform collision avoidance braking control and skid prevention control for a vehicle (100) using a braking unit that brakes the vehicle, and comprises one or more processors and one or more storage media (ROM of the predictive control unit 15) in which programs executed by one or more processors (CPU of the predictive control unit 15) are stored. The program includes one or more instructions, which cause one or more processors to perform a skid prediction process, which predicts whether the vehicle will skid during the execution of collision avoidance braking control, based on the reference vehicle behavior, which is the behavior of the vehicle when collision avoidance braking control is started, and the control value of the collision avoidance braking control; and an activation process, which enables the skid prevention control if it is disabled, in response to the skid prediction process obtaining a prediction that the vehicle will skid. According to the above configuration, even if the activation of yaw control is not included as an operating condition for collision avoidance braking control, in other words, even if collision avoidance braking control is not disabled solely by an operation to disable yaw control, yaw control can still be activated during collision avoidance braking control, thus ensuring the stability of vehicle behavior during collision avoidance braking control. Furthermore, according to the above configuration, it is possible to enable yaw control only when it is predicted that the vehicle will skid as a result of collision avoidance braking control, thus preventing yaw control from being activated even in the event of a malfunction that unnecessarily activates collision avoidance braking control. Therefore, according to this embodiment, it is possible to reduce driver inconvenience while simultaneously preventing collision avoidance braking control from being disabled by simply disabling the anti-skid control and ensuring the stability of vehicle behavior during collision avoidance braking control.

[0094] Furthermore, in the vehicle control system as an embodiment, the skid prediction process performs skid prediction based on the response characteristics of the braking unit to the braking control. This makes it possible to predict skidding based on the response characteristics of the braking system, such as the response time from when a braking control value is output until the corresponding hydraulic pressure is actually generated in the brake caliper, for collision avoidance braking control. Therefore, it becomes possible to improve the accuracy of skid prediction, enable skid prevention control at the appropriate timing, and improve the stability of vehicle behavior during collision avoidance braking control.

[0095] Furthermore, in the vehicle control system as an embodiment, the skid prediction process obtains a deceleration threshold based on the reference vehicle behavior, predicts future deceleration based on the control value output by collision avoidance braking control and response characteristics, and performs skid prediction based on the comparison result between the predicted deceleration and the threshold. This makes it possible to obtain a deceleration threshold that indicates the degree of deceleration at which skidding will occur, based on reference vehicle behavior information such as whether the vehicle is turning or driving straight, and at what speed it is traveling. Furthermore, it becomes possible to appropriately predict skidding by determining whether the future deceleration, appropriately predicted based on the control value output by collision avoidance braking control and the response characteristics of the braking unit, exceeds the threshold. Therefore, it becomes possible to improve the accuracy of skid prediction, enable appropriate activation of skid prevention control, and improve the stability of vehicle behavior during collision avoidance braking control.

[0096] Furthermore, in a vehicle control system as an embodiment, the instruction causes one or more processors to execute a first post-activation process that disables the anti-skid control based on the estimated behavior of the vehicle after the anti-skid control has been activated by the activation process. This minimizes the period during which the anti-skid control system is activated against the driver's intentions, thereby reducing driver discomfort.

[0097] Furthermore, in the vehicle control system as an embodiment, the instruction causes one or more processors to execute a second post-activation process that maintains the enabled state of the anti-skid control after the activation process has been performed, until an operation input is received instructing the deactivation of the anti-skid control. If a skid is predicted during collision avoidance braking control, it is presumed that, given the road surface conditions while the vehicle is traveling, there is a high probability that a skid will occur again if collision avoidance braking control intervenes again. Therefore, even after activating the anti-skid control as described above, the effective state is maintained. This can improve the stability of the vehicle's behavior. [Explanation of Symbols]

[0098] 100 vehicles 1. Vehicle control system 10 Imaging Unit 11L, 11R imaging unit 12 Image Processing Unit 13. Driver Support Control Unit 14. Collision Avoidance Control Unit 15 Predictive control unit 16. Vehicle speed sensor 17 Motion Sensor 18 Actual rudder angle sensor 19. Steering Torque Sensor 20 Brake control unit 21 Brake-related actuators 22 EPS control unit 23 Display section 24 Pronunciation Section 25 ESC units 26 Control section 30 Steering mechanism F1 Prediction Processing Unit F2 Activation Processing Unit F3 Post-Activation Processing Unit

Claims

1. A vehicle control system configured to perform collision avoidance braking control and skid prevention control for a vehicle using a braking unit that brakes the vehicle, One or more processors, The system comprises one or more storage media in which a program executed by the one or more processors is stored, The program includes one or more instructions, The instruction is given to one or more processors: A side-skid prediction process is performed to predict whether or not the vehicle will exhibit side-skid behavior during the execution of the collision avoidance braking control, based on the reference vehicle behavior, which is the behavior of the vehicle when the collision avoidance braking control is initiated, and the control value of the collision avoidance braking control. If the side-slip prediction process predicts that the side-slip behavior will occur, and if the side-slip prevention control is disabled, an activation process is performed to enable the side-slip prevention control. Vehicle control system.

2. In the aforementioned lateral slip prediction process, The side-slip prediction is performed based on the response characteristics of the braking unit to the braking control. The vehicle control system according to claim 1.

3. In the aforementioned lateral slip prediction process, Based on the aforementioned reference vehicle behavior, a deceleration threshold is obtained, and based on the control value output by the collision avoidance braking control and the response characteristics, future deceleration is predicted, and the skid prediction is performed based on the comparison result between the predicted deceleration and the threshold. The vehicle control system according to claim 2.

4. The instruction is given to one or more processors: After the activation of the anti-skid control by the activation process, a first post-activation process is executed to disable the anti-skid control based on the estimated behavior of the vehicle. A vehicle control system according to any one of claims 1 to 3.

5. The instruction is given to one or more processors: After the activation of the anti-skid control by the activation process described above, a second post-activation process is executed to maintain the enabled state of the anti-skid control until an operation input is received instructing the deactivation of the anti-skid control. A vehicle control system according to any one of claims 1 to 3.

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