Vehicle Control Systems

Abstract

To provide a control system of a vehicle capable of performing intervention control in an appropriate timing in collision avoidance support including warning a driver.SOLUTION: A control system 1 of a vehicle has a travel mode switching part 21 which is capable of selecting one of a plurality of travel modes and comprises: a traction control device 2 for performing traction control when a slip amount S of wheels exceeds a slip amount determination value which is set correspondingly to the travel modes; and a collision avoidance support device 5 which calculates a predicted collision time TTC which is required before the vehicle collides with an obstacle detected by an obstacle detection part 51 and outputs a warning from a warning part 53 when the predicted collision time TTC is equal to or less than a warning determination threshold value. It is configured such that the setting of the warning determination threshold value in the collision avoidance support device 5 can be changed in conjunction with the travel mode selected by the travel mode switching part 21.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle control system. [Background technology]

[0002] As a conventional vehicle control system, for example, Patent Document 1 discloses a collision avoidance support system that performs intervention control to avoid a collision with an obstacle ahead. This collision avoidance support system performs intervention control by braking operation or steering operation to avoid a collision with the obstacle according to the possibility of a collision with the obstacle ahead. In this case, the timing to start intervention control is determined based on the size of the obstacle in the estimated path of the vehicle, the relative speed to the obstacle, and road surface conditions such as snow accumulation. This makes it possible to reduce the discomfort felt by the driver due to the intervention operation without compromising safety. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4909030 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the road surface has a low coefficient of friction, such as on snowy roads, the wheels may slip (spin), causing the vehicle to wobble or the steering wheel to become unsteady, especially when starting off. This can make it difficult for drivers who are unfamiliar with the road conditions to step on the accelerator. A traction control device is known as a vehicle control mechanism for preventing wheel slip when starting or accelerating.

[0005] In a traction control system, the driver selects a driving mode from multiple preset driving modes according to the road conditions, and the control of the torque of the vehicle's drive system and the wheel brakes is switched accordingly. For example, when starting on a snowy road, the driver selects a driving mode suitable for snowy roads (snow mode). In snow mode, the timing of traction control intervention is earlier than in the standard driving mode (normal mode), stabilizing the vehicle's behavior by reducing wheel slippage. This prevents unnecessary wheel slippage (spin) even if the driver presses the accelerator too hard when starting.

[0006] However, drivers who press the accelerator pedal heavily when starting off tend to increase the vehicle's speed even when driving on snowy roads, which increases the likelihood of a collision with an obstacle ahead.The conventional collision avoidance support system mentioned above does not take into account the tendency for the likelihood of a collision corresponding to the driving mode mentioned above, and there is room for improvement.

[0007] The present invention has been made in light of the above points, and aims to provide a vehicle control system that can perform intervention control at an appropriate timing in collision avoidance assistance, including issuing an alarm. [Means for solving the problem]

[0008] In order to achieve the above object, one aspect of the present invention provides a vehicle control system including a traction control device and a collision avoidance assistance device, wherein the traction control device has a driving mode switching unit capable of selecting one of a plurality of driving modes, and when the amount of slip detected based on the rotational speed of the wheels exceeds a slip determination threshold set corresponding to the driving mode selected by the driving mode switching unit, the traction control device reduces torque of the drive device of the vehicle and / or activates a brake device of the wheel. , of the wheelsThe collision avoidance assist device includes an obstacle detection unit that detects an obstacle, a calculation unit that calculates a predicted collision time required for the vehicle to collide with the obstacle based on the relative distance and relative speed between the obstacle detected by the obstacle detection unit and the vehicle, a warning unit that can output a warning to notify the driver of the vehicle of the possibility of collision with the obstacle, and a warning control unit that causes the warning unit to output the warning when the predicted collision time calculated by the calculation unit is equal to or less than a warning determination threshold. The warning control unit is configured to be able to change the setting of the warning determination threshold in conjunction with the driving mode selected by the driving mode switching unit. [Effects of the Invention]

[0009] According to the vehicle control system of the present invention, the warning judgment threshold set in the warning control unit is changed in conjunction with the driving mode selected by the driving mode switching unit, thereby making it possible to output a warning to avoid a collision with an obstacle at a more appropriate time. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a functional configuration of a vehicle control system according to an embodiment of the present invention; [Figure 2] 10 is a flowchart showing a first example of collision avoidance control in the embodiment. [Figure 3] 10 is a flowchart showing a second example of collision avoidance control in the embodiment. [Figure 4] 10 is a first half flowchart showing a third example of collision avoidance control in the embodiment. [Figure 5] 10 is a flowchart showing the second half of a third example of collision avoidance control in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Fig. 1 is a block diagram showing the functional configuration of a vehicle control system according to one embodiment of the present invention. In Fig. 1, the vehicle control system 1 according to this embodiment includes a traction control device 2 that controls traction in a vehicle such as an automobile, and a collision avoidance support device 5 that supports operations to avoid collision between the vehicle and an obstacle.

[0012] The traction control device 2 is implemented in the control system 1 as part of the functions of an electronic stability control (ESC) system that includes antilock brake control (ABS) that suppresses locking during braking. The traction control device 2 in this embodiment includes, for example, a driving mode switching unit 21, a wheel speed sensor 22, a slip detection unit 23, and a traction control unit 24.

[0013] The driving mode switching unit 21 is configured to be able to select one of a plurality of preset driving modes. Specifically, a momentary or alternate type operation switch, a dial type operation switch, or the like can be used as the driving mode switching unit 21. The driving mode switching unit 21 allows the driver of the vehicle to select a driving mode that suits the road surface conditions. The driving mode switching unit 21 outputs a signal indicating the driving mode selected by the driver to the traction control unit 24 and the collision avoidance support device 5, respectively.

[0014] The wheel speed sensor 22 is configured to be able to detect the rotation speed of each wheel (not shown) provided on the vehicle. The rotation speed of each wheel detected by the wheel speed sensor 22 is transmitted to the slip detection unit 23.

[0015] The slip detection unit 23 detects the slip amount S of the wheel that is slipping (spinning) based on the rotational speed of each wheel detected by the wheel speed sensor 22. Specifically, the slip detection unit 23 identifies the wheel (drive wheel) that is slipping from the deviation in the rotational speed of each wheel, and calculates the slip amount S. The slip amount S of the wheel detected by the slip detection unit 23 is transmitted to the traction control unit 24.

[0016] When the slip amount S detected by the slip detection unit 23 exceeds a slip determination threshold Sth set corresponding to the driving mode selected by the driving mode switching unit 21, the traction control unit 24 controls traction by reducing the torque of the vehicle's drive devices 3 and / or activating the wheel brake devices 4 to suppress the slip. Note that, although an example has been shown in which the slip determination threshold for torque reduction in traction control and the slip determination threshold for activation of the brake devices 4 are the same value, they may also be different values. With this traction control unit 24, the start timing and control content of intervention control can be switched in accordance with the driving mode selected by the driving mode switching unit 21.

[0017] Specifically, the traction control unit 24 can be configured by combining a power controller, which is a microcomputer for executing torque control of the drive device 3, and a brake controller, which is a microcomputer for executing brake control of the brake device 4. The power controller and the brake controller are configured with a CPU, ROM, RAM, an input / output interface, etc. When the traction control is operating, the traction control unit 24 outputs a signal to the collision avoidance assistance device 5 indicating that the traction control is operating.

[0018] The drive unit 3 is composed of an internal combustion engine, an electric motor, etc. The rotational energy generated by the drive unit 3 is transmitted to the drive wheels of the vehicle via a power train (not shown). Each wheel of the vehicle is provided with a brake device 4.

[0019] Although not shown, the braking device 4 includes brakes (disc brakes, drum brakes, etc.) attached to the wheels and a brake control unit connected to the brakes via hydraulic piping. The brake control unit has a brake operation unit consisting of a brake pedal, brake booster, master cylinder, etc., and a brake actuator that controls the hydraulic pressure in accordance with a control signal from a brake controller. The brake actuator is composed of a pump that generates hydraulic pressure for brake control, a motor for driving the pump, and a valve that switches from the hydraulic system on the brake operation unit side to the hydraulic system on the brake actuator side.

[0020] The collision avoidance support device 5 is a control device for providing a function of so-called Autonomous Emergency Braking (AEB). The collision avoidance support device 5 in this embodiment includes, for example, an obstacle detection unit 51, a TTC calculation unit 52, an alarm unit 53, and a collision avoidance control unit 54.

[0021] The obstacle detection unit 51 is configured to detect an obstacle outside the vehicle and measure the relative distance between the obstacle and the vehicle. Specifically, the obstacle detection unit 51 can use a millimeter wave radar, a camera, a sonar sensor, an ultrasonic sensor, a LiDAR (Light Detection and Ranging), etc. The measurement of the relative distance by the obstacle detection unit 51 is dynamically performed at a predetermined measurement period. The obstacle detection unit 51 successively transmits the relative distance between the detected obstacle and the vehicle to the TTC calculation unit 52.

[0022] The TTC calculation unit 52 calculates the relative speed of the obstacle with respect to the vehicle using the relative distance sequentially transmitted from the obstacle detection unit 51. This relative speed can be obtained as a change in relative distance per unit time. Then, the TTC calculation unit 52 calculates a collision prediction time TTC (Time-To-Collision) required for the vehicle to collide with the obstacle based on the relative distance and relative speed between the obstacle and the vehicle detected by the obstacle detection unit 51. Specifically, the collision prediction time TTC can be obtained as a value obtained by dividing the relative distance between the obstacle and the vehicle by the relative speed. The collision prediction time TTC calculated by the TTC calculation unit 52 is transmitted to the collision avoidance control unit 54. In this embodiment, the TTC calculation unit 52 corresponds to the "calculation unit" of the present invention.

[0023] The warning unit 53 is configured to be able to output a warning to notify the driver of the possibility of a collision with an obstacle. This warning is issued to the driver by, for example, sound or a warning light, and urges the driver to avoid the collision by braking. The timing at which the warning unit 53 starts outputting the warning is controlled by the collision avoidance control unit 54.

[0024] The collision avoidance control unit 54 is provided with a signal indicating the driving mode selected by the driving mode switching unit 21 of the traction control device 2 described above, a signal indicating that traction control is in operation, and the predicted collision time TTC calculated by the TTC calculation unit 52. The collision avoidance control unit 54 performs control to cause the warning unit 53 to output a warning when the predicted collision time TTC is equal to or less than the warning determination threshold Ath. The warning determination threshold Ath set in the collision avoidance control unit 54 at this time is changeable in conjunction with the driving mode selected by the driving mode switching unit 21. In other words, the collision avoidance control unit 54 controls the warning unit 53 to output a warning at a timing appropriate for the driving mode selected by the driving mode switching unit 21.

[0025] Furthermore, the collision avoidance control unit 54 automatically activates the brake device 4 when the predicted collision time TTC is equal to or less than the brake determination threshold Bth. The brake determination threshold Bth set in the collision avoidance control unit 54 can also be changed in conjunction with the driving mode selected by the driving mode switching unit 21. However, the brake determination threshold Bth is set to a value smaller than the warning determination threshold Ath, and collision avoidance control is performed so that the brake device 4 automatically activates after an alarm is output from the alarm unit 53. In other words, the collision avoidance control unit 54 issues a warning to the driver at a timing appropriate for the driving mode selected by the driving mode switching unit 21 to encourage the driver to apply the brakes to avoid a collision. Furthermore, if the driver does not apply the brakes and a collision with an obstacle becomes unavoidable, the collision avoidance control unit 54 controls the brake device 4 to automatically (autonomously) activate the brakes to mitigate collision damage. In this embodiment, the collision avoidance control unit 54 corresponds to the "warning control unit" and "brake control unit" of the present invention.

[0026] Here, we will explain in detail, using specific examples, the multiple driving modes that can be switched by the driving mode switching unit 21, as well as the details of the slip determination threshold Sth, warning determination threshold Ath, and brake determination threshold Bth that are set corresponding to the driving mode selected by the driving mode switching unit 21.

[0027] In the vehicle control system 1 according to this embodiment, for example, four types of driving modes are set in advance: "normal mode," "snow mode," "lock mode," and "sport mode." In this embodiment, the snow mode corresponds to the "first driving mode" of the present invention, and the "lock mode" corresponds to the "second driving mode" of the present invention.

[0028] Normal mode M0 is a standard driving mode. In normal mode M0, the slip determination threshold Sth of the traction control unit 24 is set to an initial value Sth0, and the details of traction control (such as the torque reduction amount of the drive unit 3 and the braking force of the brake unit 4) are set to initial states.

[0029] The snow mode M1 is a driving mode suitable for driving on slippery road surfaces such as snow-covered roads. In the snow mode M1, a slip determination threshold value Sth1 (the first slip determination threshold value), which is smaller than the initial value Sth0 set in the normal mode M0, is set (Sth1 < Sth0), and the intervention timing of traction control is advanced compared to the normal mode M0. Note that the content of traction control in the snow mode M1 is the same as that in the normal mode M0. In the traction control of the snow mode M1, the vehicle behavior is stabilized by reducing the slip of the wheels in slippery road surface conditions such as snow-covered roads.

[0030] The lock mode M2 is a driving mode suitable for escaping from a situation where the wheels are stuck in mud, sandy ground, snow-covered roads, etc. (slip tack ). In the lock mode M2, a slip determination threshold value Sth2 (the second slip determination threshold value), which is larger than the initial value Sth0 set in the normal mode M0, is set (Sth2 > Sth0 > Sth1). While delaying the intervention timing of traction control compared to the normal mode M0, the intervention timing of the brake LSD (Limited Slip Differential) function is advanced. The brake LSD function is a function that secures the driving torque of the other driving wheel by applying a brake to the driving wheel that is slipping (spinning). In the traction control including the brake LSD function in the lock mode M2, emergency escape during stacking is supported. Such traction control similar to the lock mode M2 is also effective when starting the vehicle from a situation where the driving torque, typified by diagonal wheel lift of the vehicle, cannot be transmitted to the driving wheels, and the driving mode corresponding to this is sometimes called the "grip control mode".

[0031] The sports mode M3 is a driving mode suitable for driving while prioritizing the driver's intention. In the sports mode M3, a slip determination threshold value Sth3 (Sth3 > Sth0 > Sth1) larger than the initial value Sth0 set in the normal mode M0 is set, and the intervention timing of traction control is delayed compared to the normal mode M0. The content of traction control is set with a dedicated setting for the sports mode. In the traction control of the sports mode M3, the degree of freedom of behavior control by the driver is expanded by allowing wheel slip.

[0032] In the vehicle control system 1 according to the present embodiment, when the driver operates the driving mode switching unit 21, one of the four types of driving modes as described above is selected. Then, in conjunction with the selected driving mode, the warning determination threshold value Ath and the brake determination threshold value Bth set in the collision avoidance control unit 54 of the collision avoidance support device 5 are changed.

[0033] Specifically, when the normal mode M0 is selected by the driving mode switching unit 21, the warning determination threshold value Ath of the collision avoidance control unit 54 is set to the initial value Ath0, and the brake determination threshold value Bth is set to the initial value Bth0. The initial value Bth0 of the brake determination threshold value is smaller than the initial value Ath0 of the warning determination threshold value (Bth0 < Ath0). In the collision avoidance control in the normal mode M0, when the collision prediction time TTC is less than or equal to the initial value Ath0 of the warning determination threshold value, a warning is output from the warning unit 53, and when the collision prediction time TTC is less than or equal to the initial value Bth0 of the brake determination threshold value, the brake device 4 automatically operates to avoid a collision with an obstacle or reduce the collision damage. That is, in the collision avoidance control by the collision avoidance support device 5, a warning for prompting the driver to perform a collision avoidance operation is output before the automatic brake operates. The difference (Ath0 - Bth0) between the warning determination threshold value and the brake determination threshold value corresponds to the time (for example, 0.8 seconds) from when the warning is output until the automatic brake is started.

[0034] When the snow mode M1 (the first driving mode) is selected by the driving mode switching unit 21, for the warning determination threshold value Ath, a warning determination threshold value Ath1 (the first warning determination threshold value) larger than the initial value Ath0 set in the normal mode M0 is set (Ath1 > Ath0). Also, for the brake determination threshold value Bth, a brake determination threshold value Bth1 (the first brake determination threshold value) larger than the initial value Bth0 set in the normal mode M0 is set (Bth1 > Bth0). However, the brake determination threshold value Bth1 is smaller than the warning determination threshold value Ath1 (Bth1 < Ath1). Thereby, in the collision avoidance control in the snow mode M1, the warning output from the warning unit 53 and the automatic brake by the brake device 4 are started at a timing earlier than in the normal mode M0.

[0035] When the lock mode M2 (the second driving mode) is selected by the driving mode switching unit 21, for the warning determination threshold value Ath, a warning determination threshold value Ath2 (the second warning determination threshold value) larger than the initial value Ath0 set in the normal mode M0 is set (Ath2 > Ath0). The magnitude relationship with the warning determination threshold value Ath1 set in the above-described snow mode M1 is such that the warning determination threshold value Ath1 of the snow mode M1 is larger than the warning determination threshold value Ath2 of the lock mode M2 (Ath1 > Ath2 > Ath0). Also, for the brake determination threshold value Bth, a brake determination threshold value Bth2 (the second brake determination threshold value) the same as the initial value Bth0 set in the normal mode M0 is set (Bth2 = Bth0). The magnitude relationship with the brake determination threshold value Bth1 set in the above-described snow mode M1 is such that the brake determination threshold value Bth1 of the snow mode M1 is larger than the brake determination threshold value Bth2 of the lock mode M2 (Bth1 > Bth2 = Bth0). However, the brake determination threshold value Bth2 is smaller than the warning determination threshold value Ath2 (Bth2 < Ath2). Thereby, in the collision avoidance control in the lock mode M2, the warning output from the warning unit 53 is started at a timing earlier than in the normal mode M0 and later than in the snow mode M1, and the automatic brake by the brake device 4 is started at the same timing as in the normal mode M0.

[0036] When the sport mode M3 is selected by the driving mode switching unit 21, the warning determination threshold Ath is set to a warning determination threshold Ath3 that is the same as the initial value Ath0 set in the normal mode M0 (Ath3 = Ath0). That is, the magnitude relationship between the warning determination thresholds Ath0 to Ath3 corresponding to the four driving modes is Ath1 > Ath2 > Ath0 = Ath3. Furthermore, the brake determination threshold Bth is set to a brake determination threshold Bth3 that is the same as the initial value Bth0 set in the normal mode M0 (Bth3 = Bth0). That is, the magnitude relationship between the brake determination thresholds Bth0 to Bth3 corresponding to the four driving modes is Bth1 > Bth0 = Bth2 = Bth3. As a result, in the collision avoidance control in the sport mode M3, the warning unit 53 starts to output a warning at a later timing than in the lock mode M2, and the brake device 4 starts to automatically brake at the same timing as in the normal mode M0.

[0037] Next, the operation of the vehicle control system 1 according to this embodiment will be described in detail, focusing on the collision avoidance control executed by the collision avoidance support device 5. 2 is a flowchart showing a first example of collision avoidance control in this embodiment. In the first example, a case will be described in which, as collision avoidance control by the collision avoidance support device 5, warning control, out of warning control and brake control, is performed in conjunction with the driving mode. Note that, as the brake control in the first example is the same as conventional control, a description thereof will be omitted here.

[0038] In a first example of collision avoidance control in this embodiment, when the vehicle control system 1 is activated, first, in step S100 of Fig. 2, the warning determination threshold is set to an initial value Ath0 by the collision avoidance control unit 54 of the collision avoidance support device 5. At this time, in the collision avoidance support device 5, an output signal from the driving mode switching unit 21 of the traction control device 2 is input to the collision avoidance control unit 54, and the detection result of the obstacle detection unit 51 is transmitted to the TTC calculation unit 52.

[0039] In the following step S110, the collision avoidance control unit 54 determines whether the driving mode selected by the driving mode switching unit 21 is the snow mode M1 (first driving mode). If it is the snow mode M1 (YES), the process proceeds to the next step S120, and if it is not the snow mode M1 (NO), the process proceeds to step S130.

[0040] In step S120, the collision avoidance control unit 54 changes the warning determination threshold from the initial value Ath0 to a warning determination threshold Ath1 corresponding to the snow mode M1. The warning determination threshold Ath1 is greater than the initial value Ath0 (Ath1>Ath0). After the change to the warning determination threshold Ath1 is complete, the process proceeds to step S150.

[0041] In step S130, the collision avoidance control unit 54 determines whether the driving mode selected by the driving mode switching unit 21 is the lock mode M2 ​​(second driving mode). If it is the lock mode M2 ​​(YES), the process proceeds to the next step S140, and if it is not the lock mode M2 ​​(NO), the process proceeds to step S150.

[0042] In step S140, the collision avoidance control unit 54 changes the warning determination threshold from the initial value Ath0 to the warning determination threshold Ath2 corresponding to the lock mode M2. The warning determination threshold Ath2 is greater than the initial value Ath0 and less than the warning determination threshold Ath1 corresponding to the snow mode M1 (Ath1>Ath2>Ath0). After the change to the warning determination threshold Ath2 is complete, the process proceeds to step S150.

[0043] In step S150, the TTC calculation unit 52 calculates the relative speed of the obstacle with respect to the vehicle using the relative distance between the obstacle and the vehicle detected by the obstacle detection unit 51, and obtains the collision prediction time TTC by dividing the relative distance by the relative speed. Once the collision prediction time TTC obtained by the TTC calculation unit 52 is transmitted to the collision avoidance control unit 54, the process proceeds to the next step S160.

[0044] In step S160, the collision avoidance control unit 54 determines whether the collision prediction time TTC is equal to or less than the warning determination threshold corresponding to the driving mode. Specifically, if the snow mode M1 is selected by the driving mode switching unit 21, it determines whether the collision prediction time TTC is equal to or less than the warning determination threshold Ath1. If the lock mode M2 ​​is selected, it determines whether the collision prediction time TTC is equal to or less than the warning determination threshold Ath2. If the normal mode M0 or the sport mode M3 is selected, it determines whether the collision prediction time TTC is equal to or less than the initial value Ath0 of the warning determination threshold.

[0045] If the collision prediction time TTC is equal to or less than the warning determination threshold (YES), then in the next step S170, the collision avoidance control unit 54 controls the warning unit 53 to output a warning to notify the driver of the possibility of a collision with an obstacle. If the warning unit 53 starts to output a warning, or if the collision prediction time TTC is greater than the warning determination threshold Ath (NO in step S160), the process returns to step S100 and the above series of processes are repeated.

[0046] By performing collision avoidance control according to the first example as described above in the collision avoidance assistance device 5, it becomes possible to output a warning to avoid a collision with an obstacle at a more appropriate timing. For example, as described above, on a condition where the road surface has a low friction coefficient, such as a snowy road, the wheels may slip (spin), causing the vehicle to wobble or the steering wheel to become unsteady, particularly when starting off, making it difficult for a driver who is unfamiliar with the road surface conditions to step on the accelerator. To deal with such a situation, the driver can select the snow mode M1 in the driving mode switching unit 21 and advance the timing of traction control intervention, thereby suppressing wheel slip when starting off or accelerating.

[0047] When the driving mode switching unit 21 selects the snow mode M1, there is a high possibility that the friction coefficient of the road surface on which the vehicle is traveling is lower than that of a dry road surface. Furthermore, when the snow mode M1 is selected, the driver is also more likely to depress the accelerator pedal more than usual. In other words, even on slippery road surfaces, the traction control stabilizes the vehicle behavior, making it easier to increase speed. In the collision avoidance control of this embodiment, attention is paid to this tendency of the snow mode M1, and when the snow mode M1 is selected by the driving mode switching unit 21, the timing at which the warning unit 53 outputs a warning is made earlier than when the normal mode M0 or the sport mode M3 is selected. This encourages the driver to apply the brakes earlier, thereby increasing the possibility of avoiding a collision with an obstacle.

[0048] Furthermore, when the lock mode M2 ​​is selected by the driving mode switching unit 21, it is assumed that the driver will step on the accelerator to escape from the stuck state. In this case, there is a possibility that the vehicle will unexpectedly pick up speed after escaping from the stuck state and collide with an obstacle. For this reason, even when the lock mode M2 ​​is selected by the driving mode switching unit 21, the timing at which the warning unit 53 outputs a warning is made earlier than when the normal mode M0 or the sport mode M3 is selected. This makes it possible to prompt the driver to apply the brakes earlier, thereby increasing the possibility of avoiding a collision with an obstacle.

[0049] Comparing the cases where snow mode M1 is selected by driving mode switching unit 21 with the case where lock mode M2 ​​is selected, it is assumed that the friction coefficient of the road surface in snow mode M1 is lower than the friction coefficient of the road surface in lock mode M2. For this reason, the timing at which the warning unit 53 outputs a warning when snow mode M1 is selected is earlier than when lock mode M2 ​​is selected, thereby further increasing the possibility of avoiding a collision with an obstacle.

[0050] Next, a second example of collision avoidance control in this embodiment will be described. Figure 3 is a flowchart showing a second example of collision avoidance control in the present embodiment. In the second example, a case where both warning control and brake control are performed in conjunction with the driving mode as collision avoidance control by the collision avoidance support device 5 will be described.

[0051] In the second example of collision avoidance control in the present embodiment, when the vehicle control system 1 is activated, first, in step S200 of FIG. 3, the collision avoidance control unit 54 of the collision avoidance support device 5 sets the warning determination threshold value to the initial value Ath0, and the brake determination threshold value is set to the initial value Bth0. At this time, an output signal from the driving mode switching unit 21 of the traction control device 2 is input to the collision avoidance control unit 54 of the collision avoidance support device 5, and the detection result of the obstacle detection unit 51 is transmitted to the TTC calculation unit 52.

[0052] In the subsequent step S210, the collision avoidance control unit 54 determines whether the driving mode selected by the driving mode switching unit 21 is the snow mode M1. If it is the snow mode M1 (YES), the process proceeds to the next step S220. If it is not the snow mode M1 (NO), the process proceeds to step S230.

[0053] In step S220, the collision avoidance control unit 54 changes the warning determination threshold value from the initial value Ath0 to the warning determination threshold value Ath1 corresponding to the snow mode M1, and changes the brake determination threshold value from the initial value Bth0 to the brake determination threshold value Bth1 corresponding to the snow mode M1. The warning determination threshold value Ath1 is larger than the initial value Ath0 (Ath1 > Ath0), and the brake determination threshold value Bth1 is larger than the initial value Bth0 (Bth1 > Bth0). Also, the brake determination threshold value Bth1 is smaller than the warning determination threshold value Ath1 (Bth1 < Ath1). When the change to the warning determination threshold value Ath1 and the brake determination threshold value Bth1 is completed, the process proceeds to step S250.

[0054] In step S230, the collision avoidance control unit 54 determines whether the driving mode selected by the driving mode switching unit 21 is the lock mode M2. If it is the lock mode M2 (YES), the process proceeds to the next step S240. If it is not the lock mode M2 (NO), the process proceeds to step S250.

[0055] In step S240, the collision avoidance control unit 54 changes the warning determination threshold from the initial value Ath0 to the warning determination threshold Ath2 corresponding to the lock mode M2. The warning determination threshold Ath2 is greater than the initial value Ath0 and smaller than the warning determination threshold Ath1 corresponding to the snow mode M1 (Ath1 > Ath2 > Ath0). The brake determination threshold Bth2 corresponding to the lock mode M2 is the same as the initial value Bth0, that is, the initial value Bth0 is maintained (Bth2 = Bth0). The brake determination threshold Bth2 is smaller than the warning determination threshold Ath2 (Bth2 = Bth0 < Ath2). After the change to the warning determination threshold Ath2 is completed, the process proceeds to step S250.

[0056] In steps S250 to S270, in the same manner as steps S150 to S170 of the first example described above, the TTC calculation unit 52 obtains the collision prediction time TTC and transmits it to the collision avoidance control unit 54 (step S250). The collision avoidance control unit 54 determines whether the collision prediction time TTC is less than or equal to the warning determination threshold corresponding to the driving mode (step S260). If the collision prediction time TTC is less than or equal to the warning determination threshold, the warning unit 53 is controlled by the collision avoidance control unit 54, and a warning is output from the warning unit 53 (step S270). When the output of the warning starts, the process proceeds to the next step S280. On the other hand, if the collision prediction time TTC is greater than the warning determination threshold (NO in step S260), the process returns to step S200 and the above series of processes is repeated.

[0057] In the next step S280, the collision avoidance control unit 54 determines whether the collision prediction time TTC is equal to or less than the brake determination threshold value corresponding to the driving mode. Specifically, when the snow mode M1 is selected by the driving mode switching unit 21, it determines whether the collision prediction time TTC is equal to or less than the brake determination threshold value Bth1, and when the normal mode M0, the lock mode M2, or the sport mode M3 is selected, it determines whether the collision prediction time TTC is equal to or less than the initial value Bth0 (=Bth2, Bth3) of the brake determination threshold value.

[0058] If the collision prediction time TTC is equal to or less than the brake determination threshold (YES), then in the next step S290, the collision avoidance control unit 54 controls the braking device 4 to automatically (autonomously) apply the brakes to mitigate collision damage. If the braking device 4 applies the brakes automatically or if the collision prediction time TTC is greater than the brake determination threshold (NO in step S280), the process returns to step S200 and the above series of processes are repeated.

[0059] By performing collision avoidance control according to the second example as described above in the collision avoidance assistance device 5, it is possible to output an alarm at the appropriate time to avoid a collision with an obstacle, as in the first example described above.In addition, if the driver does not operate the brakes and a collision with an obstacle becomes unavoidable, automatic braking will be activated at the appropriate time according to the driving mode selected by the driving mode switching unit 21, thereby reducing the damage caused by the collision.

[0060] Specifically, when the snow mode M1 is selected by the driving mode switching unit 21, in situations where the driver steps on the accelerator on snowy roads, etc., it is possible to effectively mitigate damage from a collision with an obstacle by applying the automatic brakes early. Also, since the stopping distance of a traveling vehicle increases on snowy roads, etc., this increase can be compensated for by the collision avoidance support device 5 applying the automatic brakes early.

[0061] On the other hand, when the lock mode M2 ​​is selected by the driving mode switching unit 21, collision avoidance control is performed in a situation where the vehicle is attempting to escape from a stuck state, and it is predicted that the possibility of the driver stepping heavily on the accelerator after escaping is low. For this reason, an alarm is output early to prompt the driver to apply the brakes, and the timing of automatic braking is set to the same as in the normal mode M0, thereby realizing control that emphasizes collision avoidance through the driver's braking operation, making it possible to reduce damage from a collision with an obstacle while suppressing discomfort to the driver.

[0062] Next, a third example of collision avoidance control in this embodiment will be described. 4 and 5 are flowcharts showing a third example of collision avoidance control in this embodiment. In the third example, a case will be described in which collision avoidance control (warning control and automatic brake control) linked to the driving mode by the collision avoidance support device 5 is performed only while traction control is in operation.

[0063] In the third example of collision avoidance control in this embodiment, when vehicle control system 1 is activated, first, in steps S300 and S310 of Fig. 4, the warning determination threshold and brake determination threshold are set to initial values ​​Ath0 and Bth0, respectively, in the same manner as in steps S200 and S210 of the second example described above (step S300), and it is determined whether the driving mode selected by driving mode switching unit 21 is snow mode M1 (step S310). If it is snow mode M1 (YES), the process proceeds to the next step S320, and if it is not snow mode M1 (NO), the process proceeds to step S340.

[0064] In step S320, the collision avoidance control unit 54 determines whether or not traction control is operating using the output signal from the traction control unit 24. If traction control is operating, that is, if the slip amount S detected by the slip detection unit 23 exceeds the slip determination threshold and traction control is being performed to reduce the torque of the drive unit 3 and / or activate the brake unit 4 (YES), the process proceeds to the next step S330. On the other hand, if traction control is not operating, the process returns to step S310 and the determination of snow mode M1 is repeated.

[0065] In step S330, similar to step S220 in the second example described above, the collision avoidance control unit 54 changes the warning determination threshold from the initial value Ath0 to a warning determination threshold Ath1 corresponding to snow mode M1, and changes the braking determination threshold from the initial value Bth0 to a braking determination threshold Bth1 corresponding to snow mode M1. After the changes to the warning determination threshold Ath1 and the braking determination threshold Bth1 are complete, the process proceeds to step S370 (FIG. 5).

[0066] In step S340, the collision avoidance control unit 54 determines whether the driving mode selected by the driving mode switching unit 21 is the lock mode M2. If the driving mode is the lock mode M2 ​​(YES), the process proceeds to the next step S350, and if the driving mode is not the lock mode M2 ​​(NO), the process proceeds to step S370 (FIG. 5).

[0067] In step S350, similar to step S320, the collision avoidance control unit 54 determines whether or not traction control is operating. If traction control is operating (YES), the process proceeds to the next step S360, and if traction control is not operating, the process returns to step S310 and the determination of the driving mode is repeated.

[0068] In step S360, similar to step S240 in the second example described above, the collision avoidance control unit 54 changes the warning determination threshold from the initial value Ath0 to a warning determination threshold Ath2 corresponding to the lock mode M2, and maintains the brake determination threshold at the initial value Bth0. After the change to the warning determination threshold Ath2 is complete, the process proceeds to step S370 (FIG. 5).

[0069] 5, steps S370 to S410 are the same as steps S250 to S290 in the second example. That is, the TTC calculation unit 52 calculates the collision prediction time TTC and transmits it to the collision avoidance control unit 54 (step S370). The collision avoidance control unit 54 determines whether the collision prediction time TTC is equal to or less than the warning determination threshold corresponding to the driving mode (step S380). If the collision prediction time TTC is equal to or less than the warning determination threshold, the warning unit 53 outputs a warning (step S390). The collision avoidance control unit 54 then determines whether the collision prediction time TTC is equal to or less than the brake determination threshold corresponding to the driving mode (step S400). If the collision prediction time TTC is equal to or less than the brake determination threshold, automatic braking is applied (step S410).

[0070] By performing collision avoidance control according to the third example as described above in the collision avoidance support device 5, the same operational effects as in the second example described above can be obtained, and in addition, only when traction control is operating is collision avoidance control executed by changing the warning determination threshold and the brake determination threshold in conjunction with the driving mode selected by the driving mode switching unit 21, so that it is possible to prevent the timing of intervention of collision avoidance control from being switched in situations where changing the warning determination threshold and the brake determination threshold is not necessary, such as when the driver erroneously operates the driving mode switching unit 21. This makes it possible to execute collision avoidance control at a more appropriate timing.

[0071] In the third example of collision avoidance control, an example was described in which collision avoidance control is executed only when traction control is activated. However, collision avoidance control may be executed only while traction control is activated and for a predetermined time period after activation. The predetermined time period can be set to, for example, 1 to 2 seconds. This allows collision avoidance control to be performed stably even in a situation in which traction control is frequently switched on and off.

[0072] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes are possible based on the technical concept of the present invention. For example, in the above-described embodiments, an example in which four types of driving modes are switched by the driving mode switching unit 21 has been described, but the present invention is effective when switching between two or more types of driving modes is performed.

[0073] In the above-described embodiment, an example has been described in which the collision prediction time TTC is calculated based on the detection result of the obstacle detection unit 51 to perform collision avoidance control. However, collision avoidance control may also be performed by taking into account the detection results of a yaw rate sensor, a steering angle sensor, etc. in addition to the obstacle detection unit 51.

[0074] Furthermore, in the above-described embodiment, an example was described in which the first warning determination threshold Ath1 corresponding to the snow mode M1 (first driving mode) is greater than the second warning determination threshold Ath2 corresponding to the lock mode M2 ​​(second driving mode), but it is also possible to set the first and second warning determination thresholds to the same value. [Explanation of symbols]

[0075] 1...Vehicle control system 2...Traction control device 3...Driver 4...Brake device 5…Collision avoidance support device 21...Driving mode switching section 22...Wheel speed sensor 23...Slip detection unit 24...Traction control unit 51...Obstacle detection unit 52...TTC calculation section (calculation section) 53...Alarm section 54...Collision avoidance control unit Ath, Ath0 to Ath3...Alarm determination threshold Bth, Bth0 to Bth3: Brake judgment threshold M0...Normal mode M1...Snow mode (first driving mode) M2...Lock mode (second driving mode) M3…Sport mode S...Slip amount Sth, Sth0 to Sth3: Slip determination threshold TTC: Predicted Collision Time

Claims

1. a traction control device having a driving mode switching unit capable of selecting one of a plurality of driving modes, and which, when an amount of slip detected based on the rotational speed of a wheel exceeds a slip determination threshold set corresponding to the driving mode selected by the driving mode switching unit, controls traction by suppressing slip of the wheel by reducing torque of a drive device of the vehicle and / or operating a brake device of the wheel; a collision avoidance support device having: an obstacle detection unit that detects an obstacle; a calculation unit that calculates a predicted collision time required for the vehicle to collide with the obstacle based on the relative distance and relative speed between the obstacle detected by the obstacle detection unit and the vehicle; a warning unit that can output a warning to notify a driver of the vehicle of the possibility of collision with the obstacle; and a warning control unit that causes the warning unit to output the warning when the predicted collision time calculated by the calculation unit is equal to or less than a warning determination threshold; In a vehicle control system comprising: The vehicle control system is characterized in that the warning control unit is configured to be able to change the setting of the warning determination threshold in conjunction with the driving mode selected by the driving mode switching unit.

2. the plurality of driving modes includes a first driving mode, the traction control device sets a first slip determination threshold when the first driving mode is selected by the driving mode switching unit, and the first slip determination threshold is smaller than another slip determination threshold that is set when another driving mode is selected by the driving mode switching unit; 2. The vehicle control system according to claim 1, wherein the warning control unit sets a first warning determination threshold when the first driving mode is selected by the driving mode switching unit, and the first warning determination threshold is greater than another warning determination threshold that is set when another driving mode is selected by the driving mode switching unit.

3. the plurality of driving modes includes a second driving mode, the traction control device is configured to set a second slip determination threshold when the second driving mode is selected by the driving mode switching unit, and to suppress or prohibit torque reduction of the drive device and increase braking force acting on the wheels to adjust traction when the amount of slip exceeds the second slip determination threshold; 2. The vehicle control system according to claim 1, wherein the warning control unit sets a second warning determination threshold when the second driving mode is selected by the driving mode switching unit, and the second warning determination threshold is greater than another warning determination threshold that is set when another driving mode is selected by the driving mode switching unit.

4. the plurality of driving modes include a first driving mode and a second driving mode different from the first driving mode, the traction control device is configured to set a first slip determination threshold when the first driving mode is selected by the driving mode switching unit, and to set a second slip determination threshold when the second driving mode is selected by the driving mode switching unit, and to suppress or prohibit torque reduction of the drive device and increase braking force acting on the wheels to adjust traction when the first slip determination threshold is smaller than the second slip determination threshold and the amount of slip exceeds the second slip determination threshold, 2. The vehicle control system according to claim 1, wherein the warning control unit sets a first warning determination threshold when the first driving mode is selected by the driving mode switching unit, and sets a second warning determination threshold when the second driving mode is selected by the driving mode switching unit.

5. 5. The vehicle control system according to claim 4, wherein the first warning determination threshold is greater than the second warning determination threshold.

6. the collision avoidance assistance device has a brake control unit that activates the brake device when the collision prediction time calculated by the calculation unit is equal to or less than a brake determination threshold, the plurality of driving modes includes a first driving mode, the traction control device sets a first slip determination threshold when the first driving mode is selected by the driving mode switching unit, and the first slip determination threshold is smaller than another slip determination threshold that is set when another driving mode is selected by the driving mode switching unit; 6. The vehicle control system according to claim 1, wherein the brake control unit sets a first brake determination threshold when the first driving mode is selected by the driving mode switching unit, and the first brake determination threshold is greater than another brake determination threshold that is set when another driving mode is selected by the driving mode switching unit.

7. the collision avoidance assistance device has a brake control unit that activates the brake device when the collision prediction time calculated by the calculation unit is equal to or less than a brake determination threshold, the plurality of driving modes include a first driving mode and a second driving mode different from the first driving mode, the traction control device is configured to set a first slip determination threshold when the first driving mode is selected by the driving mode switching unit, and to set a second slip determination threshold when the second driving mode is selected by the driving mode switching unit, and to suppress or prohibit torque reduction of the drive device and increase braking force acting on the wheels to adjust traction when the first slip determination threshold is smaller than the second slip determination threshold and the amount of slip exceeds the second slip determination threshold, 6. The vehicle control system according to claim 1, wherein the brake control unit sets a first brake determination threshold when the first driving mode is selected by the driving mode switching unit, and sets a second brake determination threshold when the second driving mode is selected by the driving mode switching unit, and the first brake determination threshold is greater than the second brake determination threshold.

8. The vehicle control system according to any one of claims 1 to 7, characterized in that the warning control unit is configured to change the setting of the warning determination threshold only when traction control in the traction control device is operating.

9. The vehicle control system according to any one of claims 1 to 7, characterized in that the warning control unit is configured to change the setting of the warning determination threshold only while traction control in the traction control device is operating and only during a predetermined period of time after the traction control is operating.

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