Control device of vehicle

Abstract

To provide a control device of a vehicle that can operate an automatic brake more properly.SOLUTION: A control device of a vehicle makes an automatic brake generate braking force, when an own vehicle is likely to collide with an obstacle in front of the vehicle. The control device calculates rear-ender determination value DEC indexing likelihood that a following vehicle may rear end the own vehicle during deceleration of the own vehicle by the automatic brake, and determines whether or not the following vehicle is likely to rear end the own vehicle, on the basis of a result of comparison of the rear-ender determination value DEC with a predetermined threshold Dth1 for determination, and when determining that the following vehicle is likely to rear end the own vehicle, restricts the own vehicle from being decelerated by the automatic brake. The control device obtains weight data on the following vehicle through communication that is executed between the own vehicle and the following vehicle, and variably sets the threshold Dth1 for determination depending on weight of the following vehicle shown by the weight data. (Dth11 and Dth12).SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] Vehicles equipped with automatic braking systems are becoming increasingly common, with the aim of avoiding collisions with preceding vehicles and reducing damage in the event of a collision. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6365638 Summary of the Invention [Problem to be solved by the invention]

[0004] The deceleration rate by the automatic brake system is set to a rate at which a collision with the preceding vehicle can be avoided or at which the relative speed with respect to the preceding vehicle can be suppressed to a predetermined speed or less in the event of a collision.

[0005] On the other hand, if there is another vehicle (hereinafter referred to as "following vehicle") traveling behind the host vehicle, it is possible that the following vehicle may not be able to slow down in time during deceleration by the automatic braking system, resulting in a rear-end collision with the host vehicle. Taking such a situation into consideration, an upper limit value for deceleration is set, and this upper limit value acts as a guard against deceleration, thereby implementing control to prevent excessive deceleration from occurring while the automatic braking system is operating.

[0006] Here, the risk of a following vehicle rear-ending your vehicle while it is decelerating (hereinafter referred to as "rear-end collision risk of the following vehicle" or simply "rear-end collision risk") varies depending on the braking performance of the following vehicle as well as the weight of the following vehicle. As a general trend, the risk of a rear-end collision with a following vehicle increases as the weight of the following vehicle increases. When evaluating or determining the risk of a rear-end collision, the weight of the following vehicle is often assumed to be the general weight of vehicles that are expected to be encountered when driving on public roads.

[0007] However, the weight of vehicles encountered in reality varies widely. If the actual weight is greater or less than the assumed weight, the system may not necessarily provide accurate results in assessing or determining the risk of a rear-end collision, raising concerns that the system may inappropriately permit or unnecessarily restrict the operation of the automatic braking system.

[0008] Therefore, an object of the present invention is to provide a vehicle control device that can more appropriately operate an automatic brake. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, a vehicle control device according to one aspect of the present invention includes: automatic braking means that automatically generates a braking force without a driver's brake operation when there is a risk of collision of the host vehicle with an obstacle ahead of the host vehicle; following vehicle collision determination means that, during deceleration due to the braking force, calculates a collision determination value indicating a risk of a rear-end collision of a following vehicle traveling behind the host vehicle with the host vehicle and determines whether there is a risk of a rear-end collision with the following vehicle based on a comparison between the collision determination value and a predetermined determination threshold; automatic brake limiting means that, when the following vehicle collision determination means determines there is a risk of a rear-end collision with the following vehicle, limits the deceleration of the host vehicle due to the braking force; and following vehicle weight data acquisition means that acquires weight data of the following vehicle. The following vehicle weight data acquisition means acquires the weight data via communication between the host vehicle and the following vehicle, and the following vehicle collision determination means is capable of variably setting the determination threshold according to the weight of the following vehicle indicated by the weight data. [Effects of the Invention]

[0010] According to one aspect of the present invention, it is possible to avoid a collision of the host vehicle with an obstacle ahead and mitigate damage in the event of an actual collision, while preventing a situation in which a following vehicle is unable to decelerate in time and the following vehicle crashes into the host vehicle. Here, when determining whether or not there is a risk of a rear-end collision with the following vehicle, the threshold value used for the determination (i.e., the determination threshold value) can be variably set according to the weight of the following vehicle. This makes it possible to more appropriately determine the risk of a rear-end collision by optimizing or optimizing the determination threshold value, thereby avoiding situations in which deceleration by the automatic braking device is inappropriately permitted or unnecessarily restricted. Furthermore, by acquiring weight data of the following vehicle via communication between the host vehicle and the following vehicle, more accurate data regarding the weight of the following vehicle can be acquired, thereby further optimizing or optimizing the determination threshold value, thereby making it possible to more appropriately determine the risk of a rear-end collision. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing the configuration of a vehicle control device according to an embodiment of the present invention; [Figure 2] 3 is a schematic diagram showing the internal configuration of a calculation unit (controller) provided in the control device. FIG. [Figure 3] 4 is a flowchart showing the contents of automatic brake control (deceleration threshold setting process) executed by the control device. [Figure 4] 4 is a flowchart showing the contents of automatic brake control (front obstacle collision determination processing) executed by the control device. [Figure 5] 4 is a flowchart showing the contents of automatic brake control (automatic brake release processing) executed by the control device. [Figure 6] FIG. 10 is an explanatory diagram showing the tendency of change in deceleration threshold Dth1 relative to AEB operation time PRD. [Figure 7] 10 is a flowchart showing the contents of a deceleration threshold setting process according to a first modified example. [Figure 8]FIG. 10 is an explanatory diagram showing a correction coefficient HOSa based on a following vehicle collision prediction time TTCf. [Figure 9] FIG. 10 is an explanatory diagram showing a correction coefficient HOSb based on a following vehicle brake reaction time Tbrf. [Figure 10] 10 is a flowchart showing the contents of a deceleration threshold setting process according to a second modified example. [Figure 11] 10 is a flowchart showing the contents of a deceleration threshold setting process according to a third modified example. [Figure 12] FIG. 4 is an explanatory diagram showing a change in deceleration DEC during execution of automatic brake control. [Figure 13] FIG. 10 is an explanatory diagram showing a change in deceleration DEC during execution of automatic brake control (when the weight of the following vehicle is large). [Figure 14] FIG. 10 is an explanatory diagram showing a change in deceleration DEC during execution of automatic brake control (when the weight of the following vehicle is small). DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0013] (Overall configuration of vehicle control device) FIG. 1 is a schematic diagram showing the configuration of a vehicle control device (hereinafter, sometimes simply referred to as a "control device") 1 according to one embodiment of the present invention.

[0014] The control device 1 includes, as main elements related to this embodiment, a controller 101, external sensors 111 to 114, an operating state sensor 115, and a communication device 121, as well as various instruments.

[0015] The controller 101 constitutes the calculation unit of the control device 1, and generates and outputs a command signal according to the calculation result. In this embodiment, the controller 101 is composed of a microcomputer equipped with a central processing unit (CPU), storage devices such as ROM and RAM, and an input / output interface.

[0016] The external sensors 111-114, together with a driving state sensor 115 described later, constitute a detection unit of the control device 1, monitor the surroundings of the vehicle, and acquire information on the surrounding environment or situation. The external sensors 111-114 include an exterior front monitoring camera (hereinafter referred to as "front camera") 111 and a front millimeter-wave radar 113 as sensors for monitoring the front, and an exterior rear monitoring camera (hereinafter referred to as "rear camera") 112 and a rear millimeter-wave radar 114 as sensors for monitoring the rear.

[0017] The front camera 111 has a field of view set in front of the vehicle, and analyzes image data obtained by capturing images to detect obstacles ahead, such as pedestrians in front and other vehicles traveling ahead (hereinafter referred to as "leading vehicles"). In the following description, "obstacles" include roadside installations installed on the road as well as pedestrians and other vehicles other than the vehicle itself, and autonomously moving obstacles such as other vehicles may be specifically referred to as "moving obstacles."

[0018] The forward millimeter-wave radar 113 emits millimeter-wave radio waves ahead of the vehicle and receives radio waves reflected by a preceding vehicle or the like to detect the distance from the vehicle to the object, the relative speed of the vehicle to the object, and the like.

[0019] The rear camera 112 has a field of view set behind the vehicle and analyzes image data obtained by capturing images to detect following vehicles. The rear camera 112 can detect not only following vehicles, but also pedestrians behind the vehicle and obstacles installed on the road behind the vehicle.

[0020] The rear millimeter-wave radar 114 emits millimeter-wave radio waves behind the vehicle and receives radio waves reflected by a following vehicle or the like, thereby detecting the distance from the vehicle to the object, the relative speed of the vehicle to the object, and the like.

[0021] The detection signals of the external sensors 111 to 114 are output to the controller 101.

[0022] In this embodiment, the controller 101 detects a preceding vehicle traveling ahead of the host vehicle in the same lane based on the output signal from the forward camera 111, and detects the distance from the host vehicle to the preceding vehicle (hereinafter referred to as the "forward inter-vehicle distance") and the relative speed of the host vehicle to the preceding vehicle based on the output signal from the forward millimeter-wave radar 113, and calculates a predicted value (hereinafter referred to as the "predicted time to collision") TTCp of the time until the host vehicle collides with the preceding vehicle based on the forward inter-vehicle distance and the relative speed to the preceding vehicle. Furthermore, based on the output signal from the rear camera 112, the controller 101 detects a following vehicle traveling behind the own vehicle in the same lane, and based on the output signal from the rear millimeter-wave radar 114, it detects the distance from the own vehicle to the following vehicle (hereinafter referred to as the "rear inter-vehicle distance") and the relative speed of the own vehicle to the following vehicle, and calculates a predicted value TTCf of the time until the following vehicle will collide with the own vehicle (hereinafter referred to as the "following vehicle collision predicted time" or simply "rear-end collision predicted time") based on the rear inter-vehicle distance and the relative speed of the own vehicle to the following vehicle.

[0023] If the predicted time to collision TTCp with the preceding vehicle is within a predetermined time, the controller 101 determines that there is a risk of the host vehicle colliding with the preceding vehicle, and outputs a command signal to the brake actuator 201 to generate a braking force. The brake actuator 201 constitutes a driving source for a brake system provided in the vehicle. The brake system is, for example, a friction brake system, which generates a braking force on the vehicle by applying friction force to disc plates attached to the vehicle wheels (i.e., the brake wheels). The brake actuator 201 can be constituted by, for example, a hydraulic actuator. However, the brake actuator 201 can also be constituted by a generator or an electric motor capable of generating electricity as a regenerative brake actuator.

[0024] The instrument panel 301 displays indicators to alert the driver to the situation, prompting them to take action, etc. The instrument panel 301 is equipped with warning lights and alarms in addition to displays and indicator lights. The displays include various indicators that display the vehicle's driving status, such as the vehicle's speed. The indicator lights include various indicator lights that display the operation status of vehicle controls, such as traction control and vehicle stability control, and on-board devices, such as the immobilizer. The warning lights include various warning lights that warn the driver, such as when a seat belt is not fastened or when the fuel level is low, and the alarms include alarms, such as a buzzer, that are linked to the warning lights and provide auditory information to prompt the driver to recognize the warning.

[0025] The instrument panel 301 also uses a warning light and an alarm to display and notify the driver of the warning issued by the control device 1 regarding the automatic brake control. Specifically, when there is a risk of the host vehicle colliding with the preceding vehicle, the instrument panel 301 activates a warning light to display a warning regarding the collision. Furthermore, in conjunction with the warning light, the alarm is activated to notify the driver of the risk of the host vehicle colliding with the preceding vehicle by providing auditory information via a buzzer.

[0026] In addition to the above, the control device 1 is equipped with an accelerator sensor and a brake sensor (not shown) as other sensors related to automatic brake control, as well as another driving condition sensor 115. The driving condition sensor 115 is, for example, a vehicle speed sensor 115. The controller 101 can detect the amount of accelerator pedal operation APO by the driver based on the output signal from the accelerator sensor, and can detect the amount of brake pedal operation BRK by the driver based on the output signal from the brake sensor. Furthermore, the controller 101 can detect the vehicle traveling speed (hereinafter referred to as "vehicle speed") VSP based on the output signal from the vehicle speed sensor 115. The controller 101 can detect the acceleration ACC and deceleration DEC of the vehicle by calculating the rate of change per unit time of the vehicle speed VSP.

[0027] The communicator 121 includes a receiver 121a and a transmitter 121b. The vehicle (i.e., the host vehicle) can communicate with other surrounding vehicles or roadside devices via the communicator 121, enabling vehicle-to-vehicle communication with other vehicles as well as roadside-to-vehicle communication with the roadside device. Other vehicles that can communicate with the host vehicle include vehicles traveling in the same lane as the host vehicle as well as vehicles traveling in the opposite lane. In this embodiment, when there is a following vehicle behind the host vehicle, the controller 101 acquires data regarding the weight of the following vehicle (hereinafter referred to as "weight data") through communication between the host vehicle and the following vehicle. The weight data can be acquired directly from the following vehicle through vehicle-to-vehicle communication between the host vehicle and the following vehicle, or indirectly from the following vehicle via another communicator through vehicle-to-vehicle communication between the host vehicle and another vehicle other than the following vehicle or roadside-to-vehicle communication between the host vehicle and the roadside device. The controller 101 can determine the actual weight Wf of the following vehicle based on the acquired weight data.

[0028] (Internal structure of the controller) FIG. 2 is a schematic diagram showing the internal configuration of the controller 101 according to this embodiment.

[0029] In this embodiment, controller 101 detects a preceding vehicle while traveling, and if there is a risk of collision between the host vehicle and the preceding vehicle, it activates brake actuator 201 and performs control to automatically generate braking force (hereinafter referred to as "automatic brake control") without the driver's brake operation. In addition to generating braking force, controller 101 can also issue a warning and alarm to make the driver aware of the risk of collision with the preceding vehicle. Furthermore, if there is a following vehicle while automatic brake control is being performed, controller 101 determines whether there is a risk of the following vehicle colliding with the host vehicle from behind, and if it determines that there is a risk of a rear-end collision with the following vehicle, it limits deceleration by automatic brake control. Deceleration can be limited by stopping the generation of braking force itself by automatic brake control, or by continuing to generate braking force but reducing the braking force to slow down the deceleration.

[0030] The automatic brake control unit B111 determines whether or not there is a risk of the host vehicle colliding with the preceding vehicle based on the output signals from the front camera 111 and the front millimeter-wave radar 113. Specifically, when a preceding vehicle is detected based on the output signal from the front camera 111, the automatic brake control unit B111 calculates a predicted time TTCp of collision of the host vehicle with the preceding vehicle based on the forward inter-vehicle distance and the relative speed of the host vehicle with respect to the preceding vehicle output from the front millimeter-wave radar 113. Then, if the predicted time TTCp of collision is within a predetermined time TTCth1, it determines that there is a risk of collision of the host vehicle with the preceding vehicle, and outputs a command signal to the brake actuator 201 to generate a braking force on the vehicle.

[0031] The following vehicle detection unit B112 determines whether or not a following vehicle exists, in other words, whether or not a following vehicle that should be subject to rear-end collision risk assessment exists, based on the output signal from the rear camera 112. Specifically, when the rear camera 112 detects another vehicle traveling behind the host vehicle within a predetermined rear inter-vehicle distance, it determines that a following vehicle exists.

[0032] The following vehicle collision determination unit B113 determines whether there is a risk of a following vehicle colliding with the subject vehicle from behind. Specifically, it calculates a collision determination value that indicates the risk of a collision, in other words, the degree of the collision risk, and compares the collision determination value with a predetermined determination threshold. Based on the comparison result, it determines whether there is a risk of a collision. It detects the deceleration DEC of the subject vehicle while the automatic brake control is being implemented, and uses the integrated value of the deceleration DEC over time or a correlation value based on this integrated value (hereinafter, the integrated value and the correlation value are collectively referred to as the "integrated equivalent value" and hereinafter referred to as the "deceleration amount") Qdec as the collision determination value. It compares the deceleration amount Qdec with a determination threshold for the deceleration amount (hereinafter referred to as the "deceleration amount threshold") Qth1, and determines that there is a risk of a collision with the following vehicle if the deceleration amount Qdec exceeds the deceleration amount threshold Qth1.

[0033] FIG. 6 is an explanatory diagram showing the deceleration threshold Dth1, and schematically shows the tendency of change in the deceleration threshold Dth1 relative to the AEB operation time PRD.

[0034] As shown in FIG. 6, the deceleration threshold Dth1 is determined based on the time during which the deceleration DEC occurs due to the automatic brake control, in other words, the time PRD during which the brake actuator 201 is activated due to the automatic brake control (hereinafter referred to as the "AEB activation time"), and is set so that the deceleration threshold Dth1 generally decreases as the AEB activation time PRD increases. Map data for the deceleration threshold Dth1 is created in advance and stored in the storage device of the controller 101. Instead of a single deceleration threshold Dth1, multiple deceleration thresholds Dth1, Dth2 may be set according to requirements for ensuring safety against the risk of a rear-end collision, and these multiple deceleration thresholds Dth1, Dth2 may be switched depending on the situation and used for the determination by the following vehicle rear-end collision determination unit B113. In this embodiment, the deceleration amount Qdec is calculated using the following equation (1.1) as an integrated value of the deceleration DEC at each moment relative to the AEB activation time PRD. The deceleration amount threshold Qth1 is calculated by the following formula (1.2) as a product of the deceleration threshold Dth1 for the current AEB operation time PRD and the AEB operation time PRD. Qdec=ΣDEC …(1.1) Qth1=Dth1×PRD …(1.2)

[0035] The automatic brake limiting unit B114 limits deceleration of the host vehicle due to automatic brake control. In this embodiment, deceleration is limited by forcibly terminating the automatic brake control and stopping the generation of braking force by the automatic brake control itself. As mentioned above, deceleration can also be limited by reducing the braking force by adjusting the hydraulic pressure of the brake actuator 201, thereby decreasing the deceleration.

[0036] The deceleration detection unit B115 detects the deceleration DEC of the vehicle based on the output signal from the vehicle speed sensor 115.

[0037] The following vehicle weight estimation unit B116 estimates the weight Wf of the following vehicle (hereinafter referred to as "following vehicle weight"). The estimation of the following vehicle weight Wf is based on weight data acquired from the following vehicle through communication (e.g., vehicle-to-vehicle communication) between the host vehicle and the following vehicle. The following vehicle weight Wf may be the weight of the following vehicle itself, or may be the type or classification of the following vehicle according to its weight (e.g., classification as a passenger car, large vehicle, or light vehicle).

[0038] The following vehicle collision predicted time calculation unit B117 calculates a predicted value of the time until the following vehicle collides with the host vehicle, that is, a following vehicle collision predicted time TTCf, based on the output signal from the rear millimeter-wave radar 114. The following vehicle collision predicted time TTCf is calculated based on the rear inter-vehicle distance and the relative speed of the host vehicle with respect to the following vehicle.

[0039] The following vehicle brake reaction time detection unit B118 detects the brake reaction time Tbrf of the following vehicle when the following vehicle decelerates in response to the deceleration of the host vehicle due to the automatic brake control (hereinafter referred to as the "following vehicle brake reaction time" or sometimes simply referred to as the "brake reaction time"). Specifically, the following vehicle brake reaction time Tbrf is the time from when the brake actuator 201 starts to operate due to the automatic brake control or when the brake lights are turned on due to the operation of the brake actuator 201 to when the driver of the following vehicle performs a brake operation, such as by stepping on the brake pedal. The following vehicle brake reaction time Tbrf can be detected by acquiring time data related to the braking operation of the following vehicle through communication between the host vehicle and the following vehicle (for example, vehicle-to-vehicle communication). It is also possible to detect the relative deceleration of the following vehicle with respect to the host vehicle by calculating the rate of change with time of the relative vehicle speed obtained from the rear millimeter-wave radar 114, and to detect the following vehicle brake reaction time Tbrf based on the change in relative deceleration.

[0040] The following vehicle shape determination unit B119 determines the shape of the following vehicle based on the output signal from the rear camera 112. The following vehicle shape determination unit B119 further determines the vehicle type or classification (e.g., passenger car, large vehicle, or light vehicle) of the following vehicle according to the shape. The vehicle type or classification of the following vehicle correlates with the weight of the following vehicle.

[0041] The following vehicle weight Wf estimated by the following vehicle weight estimation unit B116, the following vehicle collision prediction time TTCf calculated by the following vehicle collision prediction time calculation unit B117, the following vehicle braking reaction time Tbrf detected by the following vehicle braking reaction time detection unit B118, and the type or category of the following vehicle determined by the following vehicle shape determination unit B119 are output to the following vehicle collision determination unit B113, and are used by the following vehicle collision determination unit B113 as correction reference values ​​for the determination threshold value.

[0042] Here, the following vehicle collision determination unit B113 can correct or variably set the deceleration threshold Dth1 according to the correction reference value. In this embodiment, the deceleration threshold Dth1 is decreased as the following vehicle weight Wf increases. In FIG. 6, the deceleration threshold Dth1 indicated by the solid line is used as a base value, and the deceleration threshold Dth11 set when the following vehicle weight Wf is large is indicated by a two-dot chain line, and the deceleration threshold Dth12 set when the following vehicle weight Wf is small is indicated by a single-dot chain line. For example, the deceleration threshold Dth11 set for a large following vehicle weight Wf is set to a smaller value than the reference deceleration threshold Dth1 for the same AEB operation time PRD. Correcting the deceleration threshold Dth1 also changes the deceleration threshold Qth1, which is calculated as the product of the deceleration threshold Dth1 and the AEB operation time PRD. Specifically, when the deceleration threshold Dth1 decreases, the deceleration threshold Qth1 also decreases. The correction or change of the deceleration threshold Dth1 may be made in a stepwise manner or continuously.

[0043] The following vehicle collision prediction time calculation unit B117, the following vehicle brake reaction time detection unit B118, and the following vehicle shape determination unit B119 can be appropriately employed, and one or some of them may be employed, or all of them may be employed. Furthermore, it is also possible to not employ all of them.

[0044] (Automatic brake control) Figures 3 to 5 are flowcharts showing the details of the automatic brake control according to this embodiment. The flowchart in Figure 3 shows the details of the deceleration threshold setting process, the flowchart in Figure 4 shows the details of the front obstacle collision determination process, and the flowchart in Figure 5 shows the details of the automatic brake release process.

[0045] In this embodiment, the automatic brake control is executed by the controller 101 at predetermined time intervals, and the deceleration threshold setting process is executed as background processing for the forward obstacle collision determination process and the automatic brake release process. The execution cycle of the deceleration threshold setting process may be the same as or different from the execution cycle of the forward obstacle collision determination process and the automatic brake release process. For example, the deceleration threshold setting process can be executed at a shorter cycle than the forward obstacle collision determination process and the automatic brake release process.

[0046] (Deceleration threshold setting process) In the flowchart shown in FIG. 3, in S111, various control information used in the deceleration threshold setting process is read.

[0047] In S112, it is determined whether or not a following vehicle VF exists. If a following vehicle VF exists, the process proceeds to S113, and if not, the process ends.

[0048] In S113, the weight Wf of the following vehicle is estimated.

[0049] In S114, the deceleration threshold Dth1 is set by, for example, referring to the map data shown in Fig. 6 using the AEB operation time PRD, and reading out the corrected or changed deceleration threshold Dth1 according to the weight Wf of the following vehicle.

[0050] (Front obstacle collision detection processing) In the flowchart shown in FIG. 4, in S201, various control information used in the forward obstacle collision determination process and the automatic brake release process is read.

[0051] In S202, the collision prediction time TTCp is calculated.

[0052] In S203, it is determined whether the collision prediction time TTCp is within a predetermined time TTCth1. If the collision prediction time TTCp is within the predetermined time TTCth1, the process proceeds to S204, and if it is longer than the predetermined time TTCth1, the process proceeds to S205.

[0053] In S204, it is determined whether there is a risk of the host vehicle colliding with the preceding vehicle, or whether the risk is high.

[0054] In S205, it is determined that there is no risk of the host vehicle colliding with the preceding vehicle, or that the risk is low.

[0055] In S206, the brake actuator 201 is actuated to generate a braking force on the vehicle by automatic brake control, and the automatic brake release procedure is carried out according to the procedure shown in the flowchart of FIG.

[0056] (Automatic brake release process) In the flowchart shown in FIG. 5, in S301, the deceleration DEC of the host vehicle is detected.

[0057] In S302, the collision prediction time TTCp is updated.

[0058] In S303, the deceleration threshold value Dth1 set by the deceleration threshold value setting process, that is, the deceleration threshold value Dth1 at the current AEB operation time PRD, is read.

[0059] In S304, it is determined whether the deceleration amount Qdec of the host vehicle is greater than the deceleration amount threshold value Qth1. When the deceleration amount Qdec of the host vehicle is greater than the deceleration amount threshold value Qth1 (Qth1 < Qdec), there is a risk of the following vehicle colliding with the host vehicle, and it is determined that the collision risk of the following vehicle is high, and the process proceeds to S306. When it is less than or equal to the deceleration amount threshold value Qth1 (Qdec ≦ Qth1), there is no risk of the following vehicle colliding with the host vehicle, and it is determined that the collision risk of the following vehicle is low, and the process proceeds to S305.

[0060] In S305, it is determined whether the collision prediction time TTCp is longer than a predetermined time TTCth2. When the collision prediction time TTCp is longer than the predetermined time TTCth2, it is determined that the risk of the host vehicle colliding with the preceding vehicle has been eliminated, and the process proceeds to S306. When it is within the predetermined time TTCth2, it is determined that the risk of the host vehicle colliding with the preceding vehicle still exists, and the process returns to S301 to continue deceleration by automatic brake control. The predetermined times TTCth1 and TTCth2 may be of equal length or different lengths.

[0061] In S306, the automatic brake control is terminated. That is, during deceleration by automatic brake control, when it is determined that there is a risk of the following vehicle colliding with the host vehicle, or when the collision prediction time TTCp is extended due to deceleration of the host vehicle or acceleration of the preceding vehicle, etc., and it is determined that the risk of the host vehicle colliding with the preceding vehicle has been eliminated, the automatic brake control is terminated.

[0062] Here, termination performed when there is a risk of a rear-end collision with the host vehicle by the following vehicle is a forced termination of the automatic brake control, and in this case, it becomes necessary for the driver of the host vehicle to avoid a collision with the preceding vehicle by braking himself / herself. By continuing the automatic brake control itself without terminating it and allowing the generation of deceleration by the automatic brake control within a range equal to or less than an upper limit deceleration, for example, a deceleration threshold Dth1, it becomes possible to avoid a collision with the preceding vehicle or reduce damage in the event of a collision while suppressing a rear-end collision of the following vehicle.

[0063] (Explanation of action and effect) The vehicle control device 1 according to this embodiment has the above-described configuration. The effects obtained by this embodiment will be described below.

[0064] First, during deceleration due to automatic brake control, it determines whether there is a risk of a rear-end collision with the host vehicle by the following vehicle, and if there is a risk of a rear-end collision, it limits the deceleration of the host vehicle by automatic brake control. This makes it possible to avoid a collision with a forward obstacle, such as a preceding vehicle traveling in front of the host vehicle, and to reduce damage in the event of an actual collision, while also preventing the following vehicle from slowing down in time and colliding with the host vehicle from behind.

[0065] Here, when determining whether there is a risk of a rear-end collision with a following vehicle, the judgment threshold value, in this embodiment the deceleration threshold value Dth1 used to calculate the deceleration amount threshold value Qth1, can be variably set according to the weight Wf of the following vehicle.By optimizing or optimizing the judgment threshold value, it is possible to more appropriately determine the risk of a rear-end collision and avoid situations where deceleration due to automatic brake control is inappropriately allowed or unnecessarily restricted.

[0066] For example, if the actual weight wf of the following vehicle is greater than expected, it is possible to avoid a situation in which the risk of a rear-end collision becomes apparent by inappropriately continuing deceleration through automatic brake control.On the other hand, if the actual weight Wf of the following vehicle is less than expected, it is possible to avoid a situation in which the deceleration through automatic brake control is not sufficient, thereby making the risk of a collision with a forward obstacle or a preceding vehicle more apparent.

[0067] Furthermore, by acquiring weight data of the following vehicle through communication (e.g., vehicle-to-vehicle communication) between the vehicle and the following vehicle, it becomes possible to acquire more appropriate data regarding the weight Wf of the following vehicle, thereby further optimizing or optimizing the judgment threshold value and thereby making it possible to more appropriately judge the risk of a rear-end collision.

[0068] Second, the deceleration amount Qdec, which indicates the degree of deceleration of the vehicle due to automatic brake control, is adopted as the rear-end collision judgment value, and a deceleration amount threshold Qth1 is set as the judgment threshold.If the deceleration amount Qdec exceeds the deceleration amount threshold Qth1 during deceleration due to automatic brake control, it is judged that there is a risk of a rear-end collision with the following vehicle, making it possible to easily and appropriately determine whether or not there is a risk of a rear-end collision.

[0069] Furthermore, by limiting the deceleration of the vehicle when it is determined that there is a risk of a rear-end collision with a following vehicle, the configuration for determining whether there is a risk of a rear-end collision and limiting deceleration can be simplified, making it easier to implement.

[0070] 12 to 14 are explanatory diagrams that schematically show changes in deceleration DEC during automatic brake control with respect to AEB operation time PRD. Fig. 12 shows changes in deceleration DEC when the following vehicle weight Wf is a normal or expected weight. Fig. 13 shows changes in deceleration DEC when the following vehicle weight Wf is greater than expected. Fig. 14 shows changes in deceleration DEC when the following vehicle weight Wf is smaller than expected. In each of Figs. 12 to 14, the solid line DECa shows changes when the automatic brake control is not limited by deceleration and ends normally. The dotted line DECb1 shows changes when the deceleration exceeds the normal value and the automatic brake control ends at time t32, which is earlier than the normal end time t31. The dashed-dotted line DECb2 shows changes when the deceleration does not reach the normal value and the automatic brake control ends at time t33, which is later than the normal end time t31.

[0071] 12, after the automatic brake control starts (time t0), deceleration DECa increases due to the generation of braking force (time t21) after a delay due to a time lag in the operation of brake actuator 201 or the like (time t1). After the hydraulic pressure of brake actuator 201 (hereinafter referred to as "brake hydraulic pressure") reaches a predetermined holding pressure, deceleration DECa maintains a value corresponding to the holding pressure. Then, when the collision prediction time TTCp extends and the risk of collision of the host vehicle with the preceding vehicle is eliminated and the automatic brake control ends (time t31), the braking force due to the automatic brake control disappears with the release of the brake hydraulic pressure, and deceleration DECa also decreases toward zero.

[0072] Here, under the reference deceleration threshold Dth1, the deceleration DECa does not reach the deceleration threshold Dth1 from the start (time t0) to the end (time t31) of the control, and the deceleration amount Qdec (=ΣDECa) also does not reach the deceleration amount threshold Qth1 (=Dth1×PRD), so it is not subject to restriction by the automatic brake restriction unit B114.

[0073] In contrast, if the brake hydraulic pressure exceeds the normal pressure value, causing the deceleration DECb1 to exceed the normal value DECa and further increase beyond the deceleration threshold Dth1, the automatic brake control ends (at time t32) when the deceleration Qdec (=ΣDECb1), calculated as the cumulative equivalent of the deceleration DECb1 over time, exceeds the deceleration threshold Qth1 (=Dth1×PRD), which is the product of the deceleration DECb1 and the AEB activation time PRD. In this case, even if the risk of a collision with the preceding vehicle has not been eliminated, the braking force disappears relatively quickly, and the deceleration DECb1 decreases. Figure 12 shows the deceleration threshold Qth1 calculated at time t32 using a shaded rectangular frame. The event in which the deceleration DECb1 exceeds the normal value DECa is mainly caused by an abnormality or malfunction in the controller 101 or the brake actuator 201.

[0074] On the other hand, if the brake hydraulic pressure does not reach the normal pressure value and the deceleration DECb2 remains at a value smaller than the normal value DECa, the automatic brake control ends (time t33) when the deceleration Qdec (=ΣDECb2) based on the deceleration CECb2 exceeds the deceleration threshold Qth1 (=Dth1×PRD). In this case, the deceleration DECb2 maintains its value over the relatively long AEB operation time PRD, which spans from before to after the decrease in the deceleration threshold Dth1, provided that the risk of a collision with the preceding vehicle has not been eliminated. Similarly, an event in which the deceleration DECb2 falls short of the normal value DECa is also caused by an abnormality or failure in the controller 101 or the brake actuator 201.

[0075] 13, the weight Wf of the following vehicle VF is larger than expected, and a smaller deceleration threshold Dth11 is set as a result of the correction or change made by the following vehicle collision determination unit B113, so that the deceleration amount Qdec (=ΣDECa) reaches and exceeds the deceleration amount threshold Qth1 (=Dth11×PRD) at time t31, earlier than in the case where the reference deceleration threshold Dth1 is used. As a result, the automatic brake limiting unit B114 starts limiting the deceleration, and the automatic brake control is forcibly stopped, so that the deceleration DECa decreases to 0.

[0076] Similarly, when the deceleration DECb1 exceeds the normal value DECa, the automatic brake control ends at the timing when the deceleration Qdec (=ΣDECb1) exceeds the deceleration threshold Qth1 (=Dth11×PRD) (time t32). This timing is also earlier than when the reference deceleration threshold Dth1 is used, as with the normal value DECa, because the deceleration threshold Dth11 is changed, i.e., decreased.

[0077] 14, when the weight Wf of the following vehicle VF is smaller than expected, a larger deceleration threshold Dth12 is set by the correction or change made by the following vehicle collision determination unit B113. As a result, compared to when the reference deceleration threshold Dth1 is used, the generation of braking force by automatic brake control is slightly extended, and deceleration by a relatively large braking force is permitted as long as the deceleration amount Qdec (=ΣDECa) falls within a range equal to or less than the deceleration amount threshold Qth1 (=Dth12×PRD) calculated based on the corrected deceleration threshold Dth12, and the deceleration DECa maintains its value over a longer AEB operation time PRD.

[0078] Similarly, when the deceleration DECb2 is less than the normal value DECa, the automatic brake control ends at the timing when the deceleration Qdec (=ΣDECb2) exceeds the deceleration threshold Qth1 (=Dth12×PRD) (time t33).

[0079] In addition to the above, thirdly, the deceleration threshold Dth1 is set based on the relationship with the time during which the deceleration DEC due to the automatic brake control occurs, which in this embodiment is the AEB operation time PRD. As a result, the automatic brake control can generate as high a deceleration as possible for as long as possible, within the range where it can be determined that the deceleration Qdec of the vehicle does not exceed the deceleration threshold Qth1 and there is no risk of a rear-end collision with a following vehicle, making it possible to better avoid a collision with an obstacle ahead and reduce damage in the event of a collision.

[0080] Here, by using the deceleration amount Qdec, which indicates the degree of deceleration of the host vehicle, specifically a value equivalent to the integration of the deceleration DEC over time, as an index for determination (i.e., a rear-end collision determination value), and comparing the deceleration amount Qdec with the deceleration amount threshold Qth1 (specifically, a value equivalent to the product of the deceleration threshold Dth1 and the AEB operation time PRD), it is possible to more stably determine whether or not there is a risk of a rear-end collision with the following vehicle than by comparing the deceleration DEC with the deceleration threshold Dth1 every time. This does not exclude determinations based on comparing the deceleration DEC with the deceleration threshold Dth1 every time, and it is also possible to determine that there is a risk of a rear-end collision with the host vehicle when the deceleration DEC of the host vehicle exceeds the deceleration threshold Dth1.

[0081] And fourthly, if there is a risk of a rear-end collision with a following vehicle, the generation of braking force by the automatic brake control is stopped; in other words, deceleration by the automatic brake control itself is stopped. This, despite its simple configuration, makes it possible to avoid a situation in which the risk of a rear-end collision with a following vehicle becomes apparent due to continued excessive deceleration, and also makes it possible to encourage the driver to take evasive measures by operating the brakes themselves in the event of a collision with an obstacle ahead.

[0082] As described above, the following vehicle collision prediction time calculation unit B117, the following vehicle brake reaction time detection unit B118, and the following vehicle shape determination unit B119 may use any one of these, or an appropriate combination thereof.

[0083] (First Modification) 7 is a flowchart showing the contents of the deceleration threshold setting process according to a first modification of this embodiment. In the first modification, a following vehicle collision prediction time calculation unit B117 and a following vehicle braking reaction time detection unit B118 are employed, and a following vehicle collision prediction time TTCf and a following vehicle braking reaction time Tbrf are employed as correction reference values ​​for the determination threshold.

[0084] In the flowchart shown in Fig. 7, steps S401 to S404 perform the same processing as steps S111 to S114 in the flowchart of Fig. 3. That is, in step S401, various control information used in the deceleration threshold setting processing is read, and in step S402, it is determined whether or not a following vehicle VF is present. If a following vehicle VF is present, steps S403 and onward are executed to set the deceleration threshold Dth1, whereas if a following vehicle VF is not present, the current processing ends.

[0085] The deceleration threshold Dth1 according to the first modification is set by the processes shown in S403 to S407.

[0086] In S403, the weight Wf of the following vehicle is estimated.

[0087] In S404, a basic value (hereinafter referred to as "basic deceleration threshold") Dth1 of the deceleration threshold Dth1 is set. The basic deceleration threshold Dth1 is set by referencing the map data shown in Fig. 6 using the AEB operation time PRD and reading out the corrected or changed deceleration threshold Dth1 according to the following vehicle weight Wf.

[0088] In S405, the predicted time to collision TTCf between the following vehicle and the vehicle behind is calculated.

[0089] In S406, the brake reaction time Tbrf of the following vehicle is calculated.

[0090] In S407, the basic deceleration threshold Dth1 is corrected, and the corrected deceleration threshold Dth1 is set as the final deceleration threshold Dth1 in Modification 1. Specifically, correction coefficients HOSa and HOSb are calculated according to the following vehicle rear-end collision prediction time TTCf and the following vehicle brake reaction time Tbrf, respectively, and the basic deceleration threshold Dth1 is multiplied by these correction coefficients HOSa and HOSb. Dth1 = Dth1 × HOSa × HOSb … (2)

[0091] In this embodiment, the correction coefficient HOSa is calculated by searching table data shown in Fig. 8. In the table data of Fig. 8, the correction coefficient HOSa is set to a value greater than 0 and equal to or less than 1, and tends to increase as the following vehicle collision prediction time TTCf extends. In other words, the shorter the following vehicle collision time TTCf, the shorter the rear inter-vehicle distance or the higher the relative speed of the following vehicle with respect to the host vehicle, which increases the risk of a following vehicle collision, and the deceleration threshold Dth1 is corrected to a smaller value.

[0092] Furthermore, the calculation of the correction coefficient HOSb is performed by searching table data shown in Fig. 9. In the table data of Fig. 9, the correction coefficient HOSb is set to be greater than 0 and equal to or less than 1, and to have a tendency to decrease as the following vehicle's braking reaction time Tbrf increases. In other words, the longer the following vehicle's braking reaction time Tbrf, the closer the following vehicle is to the host vehicle before it starts to decelerate, which increases the risk of a rear-end collision with the following vehicle, and therefore the deceleration threshold Dth1 is corrected to a smaller value.

[0093] In this way, by calculating the predicted time TTCf of a rear-end collision with a following vehicle and making it possible to variably set the deceleration threshold Dth1 in accordance with the predicted time TTCf of a rear-end collision with a following vehicle, it is possible to set a more appropriate deceleration threshold Dth1 in accordance with the actual predicted time TTCf of a rear-end collision, and to more appropriately determine the risk of a rear-end collision with a following vehicle.

[0094] Furthermore, by detecting the braking reaction time Tbrf of the following vehicle and making it possible to variably set the deceleration threshold Dth1 in accordance with the braking reaction time Tbrf of the following vehicle, it is possible to set a more appropriate deceleration threshold Dth1 in accordance with the actual braking reaction time Tbrf, thereby making it possible to more appropriately determine the risk of a rear-end collision with the following vehicle.

[0095] (Second Modification) 10 is a flowchart showing the contents of the deceleration threshold setting process according to a second modification of this embodiment. In the second modification, measures to be taken when a change occurs in the weight Wf of the following vehicle are introduced instead of the following vehicle collision prediction time calculation unit B117, the following vehicle brake reaction time detection unit B118, and the following vehicle shape determination unit B119.

[0096] In the flowchart shown in Fig. 10, steps S501 to S504 perform the same processing as steps S111 to S114 in the flowchart of Fig. 3. That is, in step S501, various control information used in the deceleration threshold setting processing is read, and in step S502, it is determined whether or not a following vehicle VF is present. If a following vehicle VF is present, the processing from step S503 onwards is executed to set the deceleration threshold Dth1, whereas if a following vehicle VF is not present, the current processing ends.

[0097] The deceleration threshold Dth1 according to the second modification is set by the processes shown in S503 to S507.

[0098] In S503, the weight Wf of the following vehicle is estimated.

[0099] In S504, the weight of the following vehicle Wf (= Wf n ) and the weight estimated in S504 when the deceleration threshold setting process was last executed (hereinafter referred to as the "previous weight") Wf n-1 Determine whether there is a change in the weight of the following vehicle Wf n and previous weight Wf n-1 and the weight of the following vehicle Wf n Previous weight Wf n-1 If it is determined that there is no change in the weight of the following vehicle Wf n and previous weight Wf n-1 and the weight of the following vehicle Wf n Previous weight Wf n-1 If it is determined that there is a change to the value, the process proceeds to S505.

[0100] In S505, the weight of the following vehicle Wf after the change is Wf nIt is determined whether the weight Wf of the following vehicle has been maintained for a predetermined time. n If it is maintained, the process proceeds to S507, and if it is not maintained, the process proceeds to S506.

[0101] In S506, the following vehicle weight Wf is set to a predetermined weight (hereinafter referred to as "set weight") Wset. The set weight Wset can be set to a general weight of a vehicle that is expected to be encountered when traveling on a public road, and an example of a weight that can be adopted as the set weight Wset is the general weight of a passenger car.

[0102] In S507, the deceleration threshold Dth1 is set. Specifically, the map data shown in FIG. 6 is referenced using the AEB operation time PRD, and the deceleration threshold Dth1 corrected or changed according to the following vehicle weight Wf is read out. Here, when there is a change in the following vehicle weight Wf, the following vehicle weight Wf used to set the deceleration threshold Dth1 is the set weight Wset until a predetermined time has elapsed after the change, and then the weight Wf after the change over the predetermined time is read out. n If the weight is maintained at the same level, the weight after this change will be Wf n is.

[0103] In this way, when there is a change in the weight indicated by the weight data of the following vehicle, that is, the weight Wf of the following vehicle, the predetermined weight Wset is used to set the deceleration threshold Dth1 until a predetermined time has elapsed after the change in the weight Wf of the following vehicle, and the weight Wf after the change in the weight Wf of the following vehicle over the predetermined time is used. n When maintaining the weight after change Wf n (In other words, after a change in the weight Wf of the following vehicle, a predetermined time is elapsed and the weight Wf after the change is used.) n By adopting the above method, if a change in the weight Wf of the following vehicle is due to a communication error or interruption, it is possible to quickly change the weight Wf and avoid a situation in which a weight that is significantly different from the actual weight is used to set the deceleration threshold Dth1.

[0104] (Third Modification) 11 is a flowchart showing the contents of the deceleration threshold setting process according to a third modification of this embodiment. In the third modification, a following vehicle shape determination unit B119 is employed, and the model or category of the following vehicle determined by the following vehicle shape determination unit B119 is employed as a correction reference value for the determination threshold.

[0105] In the flowchart shown in Fig. 11, steps S601 to S604 perform the same processing as steps S111 to S114 in the flowchart of Fig. 3. That is, in step S601, various control information used in the deceleration threshold setting processing is read, and in step S602, it is determined whether or not a following vehicle VF is present. If a following vehicle VF is present, steps S603 and onward are executed to set a deceleration threshold Dth1, whereas if a following vehicle VF is not present, the current processing ends.

[0106] The deceleration threshold Dth1 according to the third modification is set by the processes shown in S603 to S611.

[0107] In S603, it is determined whether or not a communication interruption has occurred between the host vehicle and the following vehicle. If a communication interruption has occurred, the process proceeds to S604, and if a communication interruption has not occurred and communication between the host vehicle and the following vehicle is still valid, the process proceeds to S607.

[0108] In S604, after communication has been interrupted, it is determined whether or not there has been a change in the shape of the following vehicle compared to the shape determined in S604 the previous time the deceleration threshold setting process was executed. The shape of the following vehicle can be determined by analyzing image data acquired by the rear camera 112, and in this embodiment, the presence or absence of a change in shape is determined based on the model or category of the following vehicle determined by the following vehicle shape determination unit B119. If there has been a change in the model or category of the following vehicle compared to the model or category determined the previous time, the process proceeds to S605, and if there has been no change, the process proceeds to S608.

[0109] In S605, it is determined whether it is possible to estimate the weight Wf based on the shape of the following vehicle. Specifically, it is determined whether the following vehicle shape determination unit B119 has completed determination of the model or category of the following vehicle currently traveling behind. If determination of the model or category of the following vehicle has been completed, proceed to S609; if not, proceed to S606.

[0110] In S606, it is determined whether a predetermined time has elapsed since the communication was interrupted. In other words, it is determined whether the communication interruption has continued for a predetermined period of time or more. If the predetermined period of time has elapsed, the process proceeds to S610. If not, the process proceeds to S608.

[0111] In S607, the weight Wf of the following vehicle is estimated. In other words, if there is no communication interruption, the weight Wf of the following vehicle is estimated based on the weight data obtained from the following vehicle via communication. The weight of the following vehicle estimated based on the weight data from the following vehicle is hereinafter referred to as the "obtained weight."

[0112] In S608, the weight Wf of the following vehicle is set to the weight estimated in S607 immediately before the communication interruption. In other words, if there is no change in the shape of the following vehicle after the communication interruption, or if there is a change but a predetermined time has not passed since the communication interruption, the weight estimated immediately before the communication interruption is set to the weight Wf of the following vehicle as the most likely weight.

[0113] In S609, the following vehicle weight Wf is set to a weight corresponding to the model or category of the following vehicle determined by the following vehicle shape determination unit B119. Specifically, a weight corresponding to the model or category of the following vehicle is assigned in advance and stored in the storage device of the controller 101. Then, based on the actually determined model or category, the corresponding weight is read out and set as the following vehicle weight Wf. If there is a change in the shape of the following vehicle after a communication interruption, the shape, i.e., the weight corresponding to the model or category of the following vehicle, is set as the following vehicle weight Wf as an estimated weight, provided that it is possible to estimate the weight Wf based on the shape.

[0114] In S610, the following vehicle weight Wf is set to the set weight Wset (Wf = Wset). In this embodiment, the set weight Wset is the same weight as that set to the following vehicle weight Wf in S506 of the flowchart shown in Fig. 10, and is the general weight of a vehicle that is expected to be encountered when traveling on a public road. In other words, if a change in the shape of the following vehicle is confirmed after a communication outage, but its weight cannot be estimated from the shape, the general weight of an expected vehicle is set to the following vehicle weight Wf as the set weight.

[0115] In S611, the deceleration threshold Dth1 is set. Specifically, the map data shown in Fig. 6 is referenced using the AEB operation time PRD, and the deceleration threshold Dth1 corrected or changed according to the following vehicle weight Wf is read out. Here, the weight Wf used to set the deceleration threshold Dth1 is the acquired weight (S607), the latest weight (S608), the estimated weight (S609), or the set weight (S610).

[0116] In this way, when communication is interrupted, the weight before the interruption is used to set the deceleration threshold Dth1 until a predetermined time has passed after the interruption (S608), and after the predetermined time has passed, a predetermined weight is used (S610).Since it is highly likely that the following vehicle has not been replaced by another vehicle immediately after the interruption, the weight before the interruption continues to be used until the predetermined time has passed, and a more likely weight is used as the following vehicle weight Wf, making it possible to more appropriately determine the risk of a rear-end collision.

[0117] Furthermore, if there is no change in the shape of the following vehicle after a disruption occurs, the weight before the disruption is used to set the deceleration threshold Dth1 (S608), while if there is a change in the shape of the following vehicle, a weight according to the shape is estimated and used to set the deceleration threshold Dth1 (S609).This makes it possible to adopt a weight that is closer to the actual weight when a disruption occurs, compared to uniformly using a predetermined hypothetical weight to set the deceleration threshold Dth1, and to more appropriately determine the risk of a rear-end collision.

[0118] In the above explanation, data relating to the weight of the following vehicle itself, i.e., weight data, is acquired through communication between the host vehicle and the following vehicle, and the following vehicle weight Wf is estimated based on the weight data. However, the estimation of the following vehicle weight Wf is not limited to this. For example, data that correlates with the weight of the following vehicle, such as the vehicle type or size (length, width), i.e., weight correlation data, can also be acquired and used to estimate the following vehicle weight Wf. Based on the weight correlation data, the following vehicle's category or classification (large vehicle, passenger car, light vehicle, etc.) is identified, and a general weight corresponding to the following vehicle's category is estimated as the following vehicle weight wf.

[0119] Furthermore, in the above explanation, the weight Wf of the following vehicle itself is used to set the determination threshold or deceleration threshold Dth1, but instead of the weight Wf itself, the weight ratio between the host vehicle and the following vehicle may be used, and the deceleration threshold Dth1 may be corrected or changed according to the weight ratio. Specifically, the greater the weight ratio of the following vehicle's weight Wf to the host vehicle, the more the deceleration threshold Dth1 is reduced, and the smaller the weight ratio of the following vehicle's weight Wf to the host vehicle, the more the deceleration threshold Dth1 is increased. [Explanation of symbols]

[0120] 1...vehicle control device, 101...controller, 111...front camera, 112...rear camera, 113...front millimeter wave radar, 114...rear millimeter wave radar, 115...vehicle speed sensor, 201...brake actuator, 301...instrument panel, 121...communicator, 121a...receiver, 121b...transmitter.

Claims

1. an automatic braking means for automatically generating a braking force without a driver's brake operation when there is a risk of collision of the host vehicle with a forward obstacle present in front of the host vehicle; a following vehicle collision determination means for calculating a collision determination value indicating a risk of a following vehicle traveling behind the host vehicle colliding with the host vehicle during deceleration due to the braking force, and determining whether or not there is a risk of a rear-end collision with the following vehicle based on a comparison between the collision determination value and a predetermined determination threshold value; an automatic brake limiting means for limiting deceleration of the host vehicle due to the braking force when the following vehicle collision determination means determines that there is a risk of a rear-end collision with the following vehicle; a following vehicle weight data acquisition means for acquiring weight data of the following vehicle, the following vehicle weight data acquisition means acquires the weight data through communication between the host vehicle and the following vehicle, A vehicle control device, wherein the following vehicle collision determination means is capable of variably setting the determination threshold value in accordance with the weight of the following vehicle indicated by the weight data.

2. 2. The vehicle control device according to claim 1, wherein the following vehicle collision determination means determines that there is a risk of a rear-end collision with the following vehicle when the rear-end collision determination value exceeds the determination threshold, and decreases the determination threshold as the weight of the following vehicle increases.

3. 3. The vehicle control device according to claim 2, wherein the following vehicle collision determination means determines that there is a risk of a rear-end collision with the following vehicle when the deceleration amount of the subject vehicle exceeds a predetermined deceleration amount threshold, which is the determination threshold, as the collision determination value during deceleration due to the braking force.

4. 3. The vehicle control device according to claim 2, wherein the following vehicle collision determination means sets the determination threshold value with a characteristic that the determination threshold value decreases as the time during which deceleration due to the braking force occurs increases, and the determination threshold value for the same occurrence time decreases as the weight of the following vehicle increases.

5. 5. A vehicle control device according to claim 1, wherein the automatic brake limiting means stops the generation of the braking force by the automatic brake means when the following vehicle collision determination means determines that there is a risk of a rear-end collision with the following vehicle.

6. a following vehicle collision predicted time calculation means for calculating a collision predicted time, which is a predicted value of the time until the following vehicle collides with the host vehicle; 5. The vehicle control device according to claim 1, wherein the following vehicle collision determination means is capable of variably setting the determination threshold value in accordance with the predicted collision time calculated by the following vehicle collision prediction time calculation means.

7. a following vehicle brake reaction time detection means for detecting a brake reaction time of the following vehicle when deceleration occurs in the following vehicle in response to deceleration of the host vehicle due to the braking force; 5. A vehicle control device according to claim 1, wherein the following vehicle rear-end collision determination means is capable of variably setting the determination threshold value in accordance with the braking reaction time of the following vehicle detected by the following vehicle braking reaction time detection means.

8. 5. A vehicle control device as claimed in any one of claims 1 to 4, wherein the following vehicle collision judgment means, when there is a change in the weight of the following vehicle indicated by the weight data of the following vehicle, sets the judgment threshold based on a predetermined weight until a first predetermined time has elapsed after the weight change, and when the weight of the following vehicle is maintained at the changed weight for the first predetermined time, sets the judgment threshold based on the weight of the following vehicle after the change.

9. 5. A vehicle control device as described in any one of claims 1 to 4, wherein, when a communication interruption occurs, the following vehicle collision judgment means sets the judgment threshold based on the weight of the following vehicle before the interruption until a second predetermined time has elapsed since the communication interruption occurred, and sets the judgment threshold based on a predetermined weight after the second predetermined time has elapsed until the communication is restored.

10. Further, a following vehicle shape determination means for determining the shape of the following vehicle is provided, 5. A vehicle control device as described in any one of claims 1 to 4, wherein, when communication is interrupted, if there is no change in the shape of the following vehicle determined by the following vehicle shape determination means, the following vehicle collision determination means sets the determination threshold based on the weight of the following vehicle before the interruption, and if there is a change in the shape of the following vehicle, estimates the weight of the following vehicle according to the determined shape and sets the determination threshold.

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