Inter-vehicle distance control device, inter-vehicle distance control method, and program thereof

Abstract

To provide an inter-vehicle distance control device, an inter-vehicle distance control method, and a program therefor capable of setting an inter-vehicle distance to a preceding vehicle to a more appropriate distance when an own vehicle stops.SOLUTION: The driving assist control ECU controls the own vehicle such that an inter-vehicle distance (own vehicle-to-vehicle distance) between the own vehicle and a preceding vehicle located immediately in front of the own vehicle is maintained at a predetermined target inter-vehicle distance. The driving support ECU is configured to acquire (1) an inter-vehicle distance between a first other vehicle stopped around the own vehicle and a second other vehicle stopped immediately in front of the first other vehicle and / or (2) an inter-vehicle distance between the first other vehicle stopped around (behind) the own vehicle and the own vehicle stopped immediately in front of the first other vehicle as an other vehicle inter-vehicle distance at the time of stop, the suitable inter-vehicle distance at the time of stopping that is set in accordance with the acquired inter-vehicle distance of the other vehicle at the time of stopping is used as the "target inter-vehicle distance when the host vehicle stops".SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle distance control device, a vehicle distance control method, and a program for controlling a vehicle distance between a host vehicle and a preceding vehicle located immediately in front of the host vehicle. [Background technology]

[0002] Conventionally, there have been known devices that perform inter-vehicle distance control to maintain the inter-vehicle distance between the host vehicle and a preceding vehicle traveling immediately in front of the host vehicle (hereinafter, sometimes referred to as the "host vehicle inter-vehicle distance") at a predetermined target inter-vehicle distance. One such device (hereinafter, sometimes referred to as the "conventional device") acquires the inter-vehicle distance between another vehicle located in the vicinity of the host vehicle and "another vehicle or the host vehicle" located immediately in front of the other vehicle (hereinafter, sometimes referred to as the "other vehicle inter-vehicle distance"). Furthermore, the conventional device changes the target inter-vehicle distance for the "host vehicle speed at the time the other vehicle inter-vehicle distance is acquired" in accordance with the acquired other vehicle inter-vehicle distance (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-189055 Summary of the Invention

[0004] However, the conventional device may set the target inter-vehicle distance when the host vehicle is stopped (i.e., the host vehicle speed is "0") based on the inter-vehicle distance between another vehicle that is moving (i.e., a vehicle whose speed is not "0") and another vehicle that is moving immediately before the other vehicle. Therefore, the conventional device has a problem in that the inter-vehicle distance when the host vehicle is stopped is likely to deviate significantly from the appropriate value.

[0005] The present invention has been made to solve the above-mentioned problems. That is, one of the objects of the present invention is to provide a vehicle distance control device, a vehicle distance control method, and a program therefor that can set a more appropriate inter-vehicle distance when the vehicle is stopped.

[0006] One aspect of the inter-vehicle distance control device according to the present invention is information acquisition devices (21, 22, 23L, 23R, 24L, 24R, 25, 26, 27L, 27R, 28L, and 28R) that acquire information about objects present around the host vehicle; a controller (10, 40, and 50) capable of performing inter-vehicle distance control, which acquires an inter-vehicle distance between the host vehicle and a preceding vehicle located immediately in front of the host vehicle based on the information (step 570), and controls the host vehicle so that the acquired inter-vehicle distance is maintained at a predetermined target inter-vehicle distance (steps 580 and 590); Equipped with.

[0007] Further, the controller The distance between a first vehicle stopped around the subject vehicle and a second vehicle stopped just before the first vehicle or the subject vehicle stopped just before the first vehicle is acquired as the inter-vehicle distance when stopped based on the information (step 950). The system is configured to use the preferred inter-vehicle distance when stopped, which is set in accordance with the acquired inter-vehicle distance when stopped, as the target inter-vehicle distance when the host vehicle is stopped (steps 970 and 720).

[0008] According to this aspect, The distance between a first other vehicle stopped around the host vehicle and a second other vehicle stopped just before the first other vehicle (see D12 to D15 in FIG. 4), and The distance between the first other vehicle stopped around the subject vehicle and the subject vehicle stopped just before the first other vehicle (see D11 in FIG. 4), is acquired as the distance between the vehicle and another vehicle when the vehicle is stopped based on "information about objects existing around the vehicle" from the information acquisition device.

[0009] Therefore, when at least one of the first other vehicle and the second other vehicle is not stopped, the inter-vehicle distance between them is not acquired as the inter-vehicle distance when stopped. Similarly, when at least one of the first other vehicle and the host vehicle is not stopped, the inter-vehicle distance between them is not acquired as the inter-vehicle distance when stopped.

[0010] The preferred inter-vehicle distance when the host vehicle is stopped, which is used as the target inter-vehicle distance when the host vehicle is stopped, is set according to the "obtained inter-vehicle distance when the host vehicle is stopped." Therefore, the target inter-vehicle distance when the host vehicle is stopped can be controlled to a preferred distance.

[0011] However, the distance that a passenger car maintains between itself and the vehicle in front when it stops is often significantly different from the distance that a vehicle other than a passenger car (e.g., a truck) maintains between itself and the vehicle in front when it stops.

[0012] Therefore, in one aspect of the above-described inter-vehicle distance control device, The controller Whether the first other vehicle is a predetermined specified vehicle type is determined based on the information (step 960), and if it is determined that the first other vehicle is the predetermined vehicle type, the inter-vehicle distance between the first other vehicle determined to be the predetermined vehicle type and the second other vehicle stopped just before the first other vehicle, and the inter-vehicle distance between the first other vehicle determined to be the predetermined vehicle type and the vehicle itself stopped just before the first other vehicle, are not reflected in the preferred inter-vehicle distance when stopped (step 970).

[0013] According to this aspect, the "inter-vehicle distance when the first other vehicle of a predetermined vehicle type is stopped," which is likely to be inappropriate as an inter-vehicle distance when the host vehicle is stopped, is not reflected in the preferable inter-vehicle distance when stopped. As a result, the inter-vehicle distance when the host vehicle is stopped can be controlled to a more appropriate distance.

[0014] In one aspect of the above-mentioned inter-vehicle distance control device, The controller When the vehicle speed of the subject vehicle becomes higher than a predetermined traffic jam travel judgment vehicle speed, the suitable inter-vehicle distance when stopped is returned to the initial value (step 710: No, step 730). Thereafter, if the preferred inter-vehicle distance when stopped is reset before a predetermined waiting period has elapsed since the host vehicle was decelerated by the inter-vehicle distance control (step 1040: Yes, step 1050, step 970, step 980), the host vehicle is moved forward so that the inter-vehicle distance matches the reset preferred inter-vehicle distance when stopped (step 1070, step 1080). It is structured as follows.

[0015] According to this aspect, when the host vehicle stops in a certain congestion environment and then temporarily exits the congestion and starts traveling (when the host vehicle speed becomes higher than a predetermined congestion traveling judgment vehicle speed), the suitable inter-vehicle distance when stopping is returned to the initial value. Then, when the host vehicle stops again in another congestion, the host vehicle is moved forward so that the inter-vehicle distance when stopping maintained by the host vehicle becomes the newly set suitable inter-vehicle distance when stopping maintained by other vehicles in the other congestion. Therefore, the inter-vehicle distance when stopping maintained by the host vehicle can be controlled to "an appropriate inter-vehicle distance according to the changing congestion environment."

[0016] In one aspect of the above-mentioned inter-vehicle distance control device, The controller When the host vehicle speed, which is the vehicle speed of the host vehicle, drops from a speed higher than a predetermined traffic congestion determination vehicle speed to a speed equal to or lower than the traffic congestion determination vehicle speed during execution of the inter-vehicle distance control, the inter-vehicle distance between a third vehicle traveling around the host vehicle and a fourth vehicle traveling just before the third vehicle or the host vehicle traveling just before the third vehicle is acquired as the inter-vehicle distance during traffic congestion based on the information (step 850), The vehicle speed at the time when the vehicle distance between the other vehicle during the traffic jam is acquired is stored as a learned vehicle speed (step 880, lookup table M1 in step 720), Calculating an appropriate inter-vehicle distance during traffic congestion based on the acquired inter-vehicle distance during traffic congestion (step 870); The optimum inter-vehicle distance during traffic congestion is stored in association with the learned vehicle speed (lookup table M1 in step 720), If the vehicle speed is lower than the learned vehicle speed, the target inter-vehicle distance is determined based on the suitable inter-vehicle distance when stopped, the suitable inter-vehicle distance while driving in a traffic jam, the learned vehicle speed, and the vehicle speed (step 720).

[0017] According to this aspect, the target inter-vehicle distance when the host vehicle speed is between zero and the learned vehicle speed can be set to an appropriate value according to the inter-vehicle distances maintained by other vehicles around the host vehicle. Furthermore, since the target inter-vehicle distance can be prevented from changing significantly between immediately before and after the host vehicle stops, the host vehicle can be stopped while smoothly decelerating.

[0018] In the above description, to facilitate understanding of the present invention, the names and / or symbols used in the embodiments described below are enclosed in parentheses for the configurations of the invention corresponding to those embodiments. However, the components of the present invention are not limited to the embodiments defined by the names and / or symbols. The present invention also covers a vehicle distance control method and a program therefor. [Brief explanation of the drawings]

[0019] [Figure 1]FIG. 1 is a schematic diagram showing the configuration of an inter-vehicle distance control device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the shooting ranges of the multiple cameras shown in FIG. [Figure 3] FIG. 2 is a diagram showing the inter-vehicle distances between other vehicles that are traveling. [Figure 4] FIG. 10 is a diagram showing the distance between other stopped vehicles. [Figure 5] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Figure 6] This is a subroutine executed by the CPU of the driving assistance ECU shown in FIG. [Figure 7] This is a subroutine executed by the CPU of the driving assistance ECU shown in FIG. [Figure 8] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Figure 9] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Figure 10] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Figure 11] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, a vehicle distance control device (hereinafter referred to as "the present control device") according to an embodiment of the present invention will be described with reference to the drawings.

[0021] (composition) The control device DS shown in FIG. 1 is mounted on the host vehicle. The host vehicle may be any of a vehicle powered by an internal combustion engine, a vehicle powered by an electric motor (i.e., an electric vehicle), a hybrid vehicle, etc. In other words, the power source of the host vehicle is not particularly limited. In this example, the host vehicle is an automobile (i.e., a passenger car) that is primarily intended for transporting people and has a capacity of, for example, 10 people or less. However, the control device DS can also be applied to vehicles of other types than passenger cars.

[0022] This control device DS includes a driving assistance ECU 10, a powertrain ECU 40, and a brake ECU 50. The driving assistance ECU 10 is sometimes referred to as the "DSECU." These ECUs are connected to each other via a communication and sensor system, the Controller Area Network (CAN), to enable data exchange. ECU is an abbreviation for Electronic Control Unit, and is also called a controller or computer. An ECU is an electronic control circuit whose main component is a microcomputer. The microcomputer includes a CPU (processor), ROM, RAM, data-writable non-volatile memory, an interface, and the like. The CPU performs various functions, which will be described later, by executing instructions (routines) stored in the memory (ROM).

[0023] The control device DS includes a plurality of camera devices and a plurality of radar devices. Each of the plurality of camera devices and each of the plurality of radar devices are connected to the DSECU via a CAN so as to be able to exchange data with the DSECU.

[0024] The multiple camera devices include a front distant camera device 21, a front camera device 22, a left front side camera device 23L, a right front side camera device 23R, a left rear side camera device 24L, a right rear side camera device 24R and a rear camera device 25.

[0025] The forward distant camera device 21 includes a camera equipped with a lens having a predetermined first horizontal angle of view, and acquires forward distant image data by photographing a scene ranging from the host vehicle to a first distance ahead of the host vehicle (see A21 in Figure 2).

[0026] Each of the front camera device 22, the left front side camera device 23L, the right front side camera device 23R, the left rear side camera device 24L, the right rear side camera device 24R and the rear camera device 25 includes a camera equipped with a wide-angle lens or an ultra-wide-angle lens, and captures a scene within a range included in a second horizontal angle of view larger than the first horizontal angle of view.

[0027] The front camera device 22 captures wide-angle front image data by capturing an image of a scene in a range from the host vehicle to a "second distance shorter than the first distance" in front of the host vehicle (see A22 in FIG. 2). The left front side camera device 23L captures a scene in a range from the host vehicle to a second distance to the left front of the host vehicle (see A23L in FIG. 2) to obtain left front wide-angle image data. The right front side camera device 23R captures right front wide-angle image data by capturing an image of a scene in a range from the host vehicle to a second distance to the right front of the host vehicle (see A23R in FIG. 2). The left rear side camera device 24L captures a scene in a range from the host vehicle to a second distance to the left rear of the host vehicle (see A24L in FIG. 2) to obtain left rear wide-angle image data. The right rear side camera device 24R captures right rear wide-angle image data by capturing an image of a scene in a range from the host vehicle to a second distance to the right rear of the host vehicle (see A24R in FIG. 2). The rear camera device 25 captures a scene in a range from the host vehicle to a second distance behind the host vehicle (see A25 in FIG. 2) to obtain rear wide-angle image data.

[0028] As shown in Fig. 2, the range of the scene captured by each of these camera devices overlaps with that of adjacent camera devices. Each of these camera devices transmits the image data it acquires to the DSECU every time a predetermined time elapses. The DSECU integrates the image data acquired by the multiple camera devices, including the front distant camera device 21. Therefore, the DSECU can acquire image data of objects located around the vehicle (within a 360-degree range centered on the vehicle) and the road surface around the vehicle every time a predetermined time elapses.

[0029] Based on the acquired image data, the DSECU recognizes (detects) the "left and right boundary lines" of the host vehicle's lane, the "left and right boundary lines" of the adjacent lane to the left of the host vehicle, and the "left and right boundary lines" of the adjacent lane to the right of the host vehicle. Note that lane boundaries are generally lane markings, such as white and yellow lines. Furthermore, the DSECU generates camera object information based on the acquired image data. The camera object information includes information that identifies the "position (longitudinal and lateral positions) and type" of objects present around the host vehicle. The object type includes the vehicle type of the other vehicle (e.g., vehicle type such as passenger car, truck, bus, motorcycle, etc.).

[0030] As shown in FIG. 1, the plurality of radar devices include a front radar device 26, a left front-side radar device 27L, a right front-side radar device 27R, a left rear-side radar device 28L, and a right rear-side radar device 28R.

[0031] Each of the multiple radar devices is a well-known device that acquires information about objects present around the vehicle using millimeter-wave radio waves. Simply put, each radar device transmits millimeter waves within a predetermined detection range and receives millimeter waves reflected by the objects, thereby acquiring information about the objects present within the respective detection range (i.e., radar information) based on the information about the transmitted and received millimeter waves.

[0032] The front radar device 26 acquires radar information about objects that exist within a predetermined detection range ahead of the vehicle. The left front-side radar device 27L acquires radar information about objects that exist within a predetermined detection range on the left front side of the vehicle. The right front-side radar device 27R acquires radar information about objects that exist within a predetermined detection range on the right front side of the vehicle. The left rear-side radar device 28L acquires radar information about objects that exist within a predetermined detection range on the left rear side of the vehicle. The right rear-side radar device 28R acquires radar information about objects that exist within a predetermined detection range on the right rear side of the vehicle.

[0033] Each of these radar devices transmits the acquired radar information to the DSECU every time a predetermined time elapses. The DSECU acquires radar object information based on the radar information acquired by the multiple radar devices. The radar object information includes the distance between the object and the location where each radar device is installed, the direction of the object relative to the location where each radar device is installed, and the relative speed of the object relative to each radar device. The detection range of the left rear-side radar device 28L and the detection range of the right rear-side radar device 28R overlap behind the vehicle.

[0034] The DSECU integrates the radar object information generated based on the radar information acquired by the multiple radar devices to generate radar integrated object information about objects present around the vehicle (excluding the immediate vicinity of the vehicle to the side). The radar integrated object information includes "the direction and speed of the object relative to the vehicle, etc."

[0035] The DSECU combines the camera object information and the radar integrated object information to generate fusion object information, which is the final object information about objects present around the host vehicle.

[0036] Furthermore, the DSECU is connected to an ACC operation switch 31, a vehicle speed sensor 32, and an accelerator pedal operation amount sensor 33, and receives output signals from these.

[0037] The ACC operation switch 31 is a switch operated by the driver of the host vehicle. ACC stands for adaptive cruise control. ACC includes adaptive distance control (sometimes simply referred to as "interval control") and constant speed control.

[0038] When the driver performs a predetermined operation on the ACC operation switch 31, the DSECU determines that a request such as an ACC start request, an ACC end request, or an ACC resume request has occurred in response to that operation. Furthermore, when another predetermined operation is performed on the ACC operation switch 31, the DSECU changes the target inter-vehicle time Ttgt. The target inter-vehicle time Ttgt is selected from a first time T1 corresponding to a long target inter-vehicle distance, a second time T2 corresponding to a medium target inter-vehicle distance, and a third time T3 corresponding to a short target inter-vehicle distance.

[0039] The vehicle speed sensor 32 detects the speed of the host vehicle (host vehicle speed) Vh, and outputs a signal indicative of the host vehicle speed Vh.

[0040] The accelerator pedal operation amount sensor detects the operation amount of an accelerator pedal (accelerator pedal operation amount AP) of the vehicle (not shown), and outputs a signal indicative of the accelerator pedal operation amount AP.

[0041] The powertrain ECU 40 is connected to a powertrain sensor 41 and a powertrain actuator 42. The powertrain ECU 40 receives detection signals from the powertrain sensor 41. When the drive source is an internal combustion engine, the powertrain sensor 41 includes an intake air volume sensor, an engine rotation speed sensor, etc. The powertrain ECU 40 controls a drive device including a power source of the host vehicle (not shown) by driving the powertrain actuator 42, thereby controlling the acceleration of the host vehicle by adjusting the drive force of the host vehicle.

[0042] The brake ECU 50 is connected to a brake sensor 51 and a brake actuator 52. The brake ECU 50 receives a detection signal from the brake sensor 51. The brake sensor 51 includes a brake pedal operation amount sensor and a wheel speed sensor that detects the wheel speed of each wheel. The brake ECU 50 controls a braking device of the host vehicle (not shown) by driving the brake actuator 52, thereby controlling the acceleration (deceleration) of the host vehicle by adjusting the braking force applied to the host vehicle.

[0043] (Overview of operation) As shown in Figure 3, when the ACC execution condition is met, the control device DS performs inter-vehicle distance control (following inter-vehicle distance control) to make the host vehicle HV follow the preceding vehicle PV so that the actual inter-vehicle distance (i.e., host vehicle inter-vehicle distance) Dact between the host vehicle HV and the preceding vehicle PV located immediately before the host vehicle HV is maintained at a predetermined target inter-vehicle distance Dtgt.

[0044] The target inter-vehicle distance Dtgt is set to the product (Vh·Ttgt) of the host vehicle speed Vh and the above-mentioned target inter-vehicle time Ttgt set by the driver of the host vehicle HV during normal driving (when not driving in a congested environment).

[0045] When the host vehicle HV is traveling in a traffic jam but is not stopped (i.e., when the host vehicle speed Vh is equal to or less than the traffic jam travel determination vehicle speed VJth and greater than the positive extremely low speed determination value VLth), the control device DS acquires the following "inter-vehicle distances D1 to D5 (see FIG. 3)" as the inter-vehicle distances between other vehicles traveling in the traffic jam based on "camera object information or fusion object information." Note that the "speed equivalent to the host vehicle speed Vh" is equal to or greater than a speed V1th obtained by subtracting a positive first predetermined value dV1 from the host vehicle speed Vh and equal to or less than a speed V2th obtained by adding a positive second predetermined speed dV2 to the host vehicle Vh.

[0046] Inter-vehicle distance D1: The inter-vehicle distance between the host vehicle HV and a rear vehicle C1 (third other vehicle) located immediately behind the host vehicle HV in the host lane and traveling at a speed equal to the host vehicle speed Vh (i.e., a vehicle speed greater than "0"). Inter-vehicle distance D2: The inter-vehicle distance between another vehicle C3 (third other vehicle) traveling in the same direction as the subject vehicle HV in the left adjacent lane at a speed equal to the subject vehicle speed Vh (i.e., a vehicle speed greater than "0") and another vehicle C2 (fourth other vehicle) traveling immediately before the subject vehicle C3. Inter-vehicle distance D3: The inter-vehicle distance between another vehicle C4 (third other vehicle) traveling in the same direction as the subject vehicle HV in the left adjacent lane at a speed equal to the subject vehicle speed Vh (i.e., a vehicle speed greater than "0") and another vehicle C3 (fourth other vehicle) traveling immediately before the subject vehicle C4. Inter-vehicle distance D4: The inter-vehicle distance between another vehicle C6 (third other vehicle) traveling in the same direction as the subject vehicle HV in the right adjacent lane at a speed equal to the subject vehicle speed Vh (i.e., a vehicle speed greater than "0") and another vehicle C5 (fourth other vehicle) traveling immediately before the subject vehicle C6. Inter-vehicle distance D5: The inter-vehicle distance between another vehicle C7 (third other vehicle) traveling in the same direction as the subject vehicle HV in the right adjacent lane at a speed equal to the subject vehicle speed Vh (i.e., a vehicle speed greater than "0") and another vehicle C6 (fourth other vehicle) traveling immediately before the subject vehicle C7.

[0047] Note that, among these inter-vehicle distances, if the other vehicle is a vehicle of a predetermined model (specifically, a large vehicle such as a truck or bus, or a motorcycle) different from the model / type of the host vehicle HV (a passenger car in this example), the control device DS considers the inter-vehicle distance maintained by the other vehicle not to be a valid "inter-vehicle distance from another vehicle while traveling in a traffic jam." For example, in the above example shown in Figure 3, if the other vehicle C3 is a truck, the control device DS considers the inter-vehicle distance D2 not to be a valid "inter-vehicle distance from another vehicle while traveling in a traffic jam."

[0048] When one or more (preferably two or more) valid "inter-vehicle distances while traveling in a traffic jam" are obtained, the control device DS calculates the suitable inter-vehicle distance Dm while traveling in a traffic jam based on the valid "inter-vehicle distances while traveling in a traffic jam." For example, the control device DS calculates the average value of the valid "inter-vehicle distances while traveling in a traffic jam" as the suitable inter-vehicle distance Dm while traveling in a traffic jam. Then, the control device DS stores (learns) the suitable inter-vehicle distance Dm while traveling in a traffic jam as the target inter-vehicle distance Dtgt for the learned vehicle speed Vm, which is the host vehicle speed Vh when the valid inter-vehicle distance used to calculate the suitable inter-vehicle distance Dm while traveling in a traffic jam was obtained.

[0049] In addition, when the host vehicle HV is in a traffic jam environment and is stopped or traveling at an extremely slow speed (i.e., when the host vehicle speed Vh is equal to or less than the positive extremely slow speed judgment value VLth), the control device DS acquires the "inter-vehicle distances D11 to D15 (see Figure 4)" described below as the inter-vehicle distances from other vehicles when stopped based on "camera object information or fusion object information."

[0050] Inter-vehicle distance D11: Inter-vehicle distance between the host vehicle HV and a rear vehicle C1 (first other vehicle) that is stopped immediately behind the host vehicle HV in the host lane. Inter-vehicle distance D12: The inter-vehicle distance between a stopped vehicle C3 (first other vehicle) and a stopped vehicle C2 (second other vehicle) immediately preceding the stopped vehicle C3 in the adjacent left lane. Inter-vehicle distance D13: Inter-vehicle distance between a stopped vehicle C4 (first other vehicle) and a stopped vehicle C3 (second other vehicle) immediately preceding the stopped vehicle C4 in the adjacent left lane. Inter-vehicle distance D14: Inter-vehicle distance between a stopped vehicle C6 (first other vehicle) and a stopped vehicle C5 (second other vehicle) immediately preceding the stopped vehicle C6 in the adjacent lane to the right. Inter-vehicle distance D15: Inter-vehicle distance between a stopped vehicle C7 (first other vehicle) and a stopped vehicle C6 (second other vehicle) immediately preceding the stopped vehicle C7 in the adjacent lane to the right.

[0051] Even in this case, if the other vehicle is a vehicle of a predetermined model different from the model / type of the host vehicle HV (in this example, a passenger car), the control device DS considers the inter-vehicle distance maintained by the other vehicle not to be a valid "inter-vehicle distance when stopped." For example, in the above example shown in Figure 4, if the other vehicle C3 is a truck, the control device DS considers the inter-vehicle distance D12 not to be a valid "inter-vehicle distance when stopped."

[0052] When one or more (preferably two or more) valid "inter-vehicle distances when stopped" are obtained, the control device DS calculates the suitable inter-vehicle distance D0 when stopped based on the valid "inter-vehicle distances when stopped." For example, the control device DS calculates the average value of the valid "inter-vehicle distances when stopped" as the suitable inter-vehicle distance D0 when stopped. Then, the control device DS stores (learns) the suitable inter-vehicle distance D0 when stopped as the target inter-vehicle distance Dtgt for when the host vehicle speed Vh is "0."

[0053] After the preferred inter-vehicle distance Dm during traffic congestion and the preferred inter-vehicle distance D0 when stopped are acquired (learned), the control device calculates the target inter-vehicle distance Dtgt during traffic congestion based on the preferred inter-vehicle distance Dm during traffic congestion, the preferred inter-vehicle distance D0 when stopped, the learned vehicle speed Vm, and the current vehicle speed Vh, for example, using linear interpolation for the vehicle speed Vh.

[0054] When the preferred inter-vehicle distance D0 when stopping has not been acquired, the control device DS sets the preferred inter-vehicle distance D0 when stopping to a preset initial value D0int. Therefore, when the host vehicle HV stops in a state where the preferred inter-vehicle distance Dm when traveling in a traffic jam has been learned but the preferred inter-vehicle distance D0 when stopping has not been learned, the inter-vehicle distance between the host vehicle HV and the preceding vehicle PV becomes a value close to the initial value D0int of the preferred inter-vehicle distance when stopping. In this case, if the preferred inter-vehicle distance D0 when stopping is learned between the time the host vehicle HV stops and the predetermined waiting time has elapsed, and the learned preferred inter-vehicle distance D0 when stopping is shorter than the actual host vehicle inter-vehicle distance Dact, the control device DS causes the host vehicle HV to creep so that the actual host vehicle inter-vehicle distance Dact matches the learned preferred inter-vehicle distance D0 when stopping.

[0055] In this way, according to the present control device DS, the actual inter-vehicle distance Dact is adjusted based on the inter-vehicle distances maintained by other vehicles around the host vehicle HV (inter-vehicle distances), reducing the possibility that the driver will feel uncomfortable. Furthermore, according to the present control device DS, the preferred inter-vehicle distance D0 when stopped is a distance calculated based on the distance between two stopped vehicles (vehicles that are not moving), and therefore is a preferred inter-vehicle distance to be maintained when the host vehicle HV is stopped.

[0056] (Specific operation) The CPU of the DSECU (hereinafter, when the term "CPU" is used, it refers to the CPU of the DSECU unless otherwise specified) is configured to execute the routine shown in the flowcharts of Figure 5 and Figures 8 to 11 every time a predetermined time has elapsed.

[0057] 1. ACC driving control (vehicle distance control) At a predetermined timing, the CPU starts processing from step 500 in FIG. 5 and determines in step 510 whether the value of the ACC execution flag XACC is "1." The value of the ACC execution flag XACC is set to "1" by a routine (not shown) when the ACC start condition is met, and is set to "0" by a routine (not shown) when the ACC termination condition is met. The ACC start condition is met, for example, when an ACC start request is generated by operating the ACC operation switch 31 while ACC is not being executed (i.e., when the value of the ACC execution flag XACC is set to "0"), and the vehicle speed Vh at that time is higher than the traffic jam traveling determination vehicle speed VJth. The ACC termination condition is met, for example, when an ACC termination request is generated by operating the ACC operation switch 31 while the value of the ACC execution flag XACC is set to "1."

[0058] The ACC execution flag XACC is set to "0" by an initialization routine (not shown) executed by the CPU when the start switch (e.g., ignition key switch and ready switch) (not shown) of the host vehicle HV is changed from the OFF position to the ON position.

[0059] If the value of the ACC execution flag XACC is "1", the CPU determines "Yes" in step 510 and proceeds to step 520 to determine whether or not a preceding vehicle to be followed (i.e., a vehicle to be followed) is present in the own lane. For example, when there is another vehicle traveling immediately in front of the own vehicle in the own lane and the inter-vehicle distance between the other vehicle and the own vehicle is within a predetermined threshold inter-vehicle distance, the CPU determines that the other vehicle is a vehicle to be followed.

[0060] If a vehicle to be followed is present, the CPU proceeds from step 520 to step 530 and determines whether the value of the ACC permission flag XALW is "1." The value of the ACC permission flag XALW is set to "1" when the value of the ACC execution flag XACC changes from "0" to "1," and is set to "0" when a predetermined waiting time has elapsed since the host vehicle HV was stopped by ACC (see step 1090 in FIG. 10, described later). Furthermore, the value of the ACC permission flag XALW is set to "1" if the driver performs a start operation while the value is "0" (see step 1170 in FIG. 11, described later).

[0061] After ACC starts, the value of the ACC permission flag XALW is usually "1." In this case, the CPU determines "Yes" in step 530 and proceeds to step 540 to determine whether the value of the traffic congestion driving flag XJ is "0." The value of the traffic congestion driving flag XJ is set to "0" when the value of the ACC execution flag XACC described above changes from "0" to "1." Furthermore, if the value of the ACC execution flag XACC is "1" (i.e., while ACC is being executed), the value of the traffic congestion driving flag XJ is changed to "1" (see step 640 in FIG. 6, described later) when the host vehicle speed Vh becomes equal to or less than the traffic congestion driving determination vehicle speed VJth, and is changed to "0" (see step 730 in FIG. 7, described later) when the host vehicle speed Vh becomes higher than the traffic congestion driving determination vehicle speed VJth.

[0062] If the value of the traffic jam driving flag XJ is "0", the CPU determines "Yes" in step 540 and proceeds to step 550, where it executes a subroutine shown in Fig. 6 (to be described later) to obtain (calculate) the target inter-vehicle distance Dtgt for normal driving. Thereafter, the CPU proceeds to step 570.

[0063] On the other hand, if the value of the traffic jam driving flag XJ is "1", the CPU determines "No" in step 540 and proceeds to step 560, where it executes a subroutine shown in Fig. 7, which will be described later, to obtain (calculate) the target inter-vehicle distance Dtgt for traffic jam driving. Thereafter, the CPU proceeds to step 570.

[0064] In step 570, the CPU acquires (measures) the aforementioned host vehicle distance Dact (the actual distance between the host vehicle HV and the preceding vehicle PV located immediately in front of the host vehicle HV, as shown in FIG. 2) based on the fusion object information. Furthermore, the CPU acquires the relative speed Vrelative of the preceding vehicle PV with respect to the host vehicle HV based on the fusion object information. Note that the relative speed Vrelative takes a positive value when the preceding vehicle PV is moving away from the host vehicle HV.

[0065] Next, the CPU proceeds to step 580 and calculates the target acceleration Gtgt according to the following equations (1) and (2). The target inter-vehicle distance Dtgt in equation (1) is the target inter-vehicle distance acquired in either step 550 or step 560. K1 and K2 in equation (2) are predetermined positive gains (coefficients). Note that an acceleration term (K3·dVrelative / dt) may be added to the right-hand side of equation (2). Inter-vehicle distance deviation ΔD = host vehicle inter-vehicle distance Dact - target inter-vehicle distance Dtgt ... (1) Target acceleration Gtgt=K1·ΔD + K2·Vrelative …(2)

[0066] Next, the CPU proceeds to step 590, where it sends instructions to the powertrain ECU 40 and the brake ECU 50 to control the acceleration of the host vehicle HV so that the actual acceleration of the host vehicle HV (the amount of change in the host vehicle speed Vh per unit time) coincides with the target acceleration Gtgt. This executes inter-vehicle distance control, where the host vehicle HV is accelerated or decelerated so that the inter-vehicle distance Dact coincides with the target inter-vehicle distance Dtgt. The CPU then proceeds to step 595, where it temporarily ends this routine.

[0067] If the CPU determines "No" in any of steps 510 to 530, it proceeds directly to step 595 from the step where it determined "No."

[0068] 2. Acquisition of target inter-vehicle distance for normal driving As described above, when the CPU proceeds to step 550 in Fig. 5, it executes the subroutine shown in Fig. 6 to obtain (calculate) the target inter-vehicle distance for normal driving. More specifically, when the CPU proceeds to step 550, it starts processing from step 600 in Fig. 6 and proceeds to step 610 to determine whether the host vehicle speed Vh is higher than the traffic jam driving determination vehicle speed VJth. If the host vehicle speed Vh is higher than the traffic jam driving determination vehicle speed VJth, the CPU determines "Yes" in step 610, sequentially performs the processing of "steps 620 and 630" described below, proceeds to step 695, and temporarily ends this routine.

[0069] Step 620: The CPU reads the target inter-vehicle time Ttgt set by the driver. Step 630: The CPU sets the target inter-vehicle distance Dtgt to the product of the target inter-vehicle time Ttgt and the vehicle speed Vh.

[0070] On the other hand, when the CPU proceeds to step 610, if the host vehicle speed Vh is equal to or lower than the traffic jam travel determination vehicle speed VJth, the CPU determines "No" in step 610 and proceeds to step 640. The CPU sets the value of the traffic jam travel flag XJ to "1" in step 640, and proceeds to step 695. In this case, the target inter-vehicle distance Dtgt is set to the product of the target inter-vehicle time Ttgt and the host vehicle speed Vh.

[0071] 3. Acquisition of target inter-vehicle distance for driving in traffic jams As described above, when the CPU proceeds to step 560 in Fig. 5, it executes the subroutine shown in Fig. 7 to obtain (calculate) the target inter-vehicle distance for driving in traffic congestion. More specifically, when the CPU proceeds to step 560, it starts processing from step 700 in Fig. 7 and proceeds to step 710 to determine whether the host vehicle speed Vh is equal to or less than the traffic congestion driving determination vehicle speed VJth. If the host vehicle speed Vh is equal to or less than the traffic congestion driving determination vehicle speed VJth, the CPU determines "Yes" in step 710 and proceeds to step 720.

[0072] In step 720, the CPU obtains (calculates) the target inter-vehicle distance Dtgt based on the data stored in the look-up table M1 and the current vehicle speed Vh of the host vehicle. The look-up table M1 defines the relationship between the vehicle speed Vh of the host vehicle and the target inter-vehicle distance Dtgt. The CPU calculates the target inter-vehicle distance Dtgt according to the following equations (3) to (5) in accordance with the linear interpolation method. Thereafter, the CPU proceeds to step 795 and temporarily ends this routine. Note that DJth is the target inter-vehicle distance Dtgt when the vehicle speed Vh of the host vehicle is the traffic jam driving determination vehicle speed VJth, and is set in advance. Vm is the learned vehicle speed Vm described above, and Dm is the preferred inter-vehicle distance during traffic jam driving described above. These values (Vm, Dm) are learned by the routine of FIG. 8 described later. D0 is the preferred inter-vehicle distance D0 at the time of stop described above, and is learned by the routine of FIG. 9 described later.

[0073] (Case 1) When the value of the learning flag XDm during traffic jam driving is "1" (that is, when the learned vehicle speed Vm and the preferred inter-vehicle distance Dm during traffic jam driving are learned and not cleared) · When 0 ≤ Vh ≤ Vm Dtgt = D0 + (Dm - D0)·(Vh / Vm) …(3) · When Vm < Vh ≤ VJth Dtgt = Dm + (DJth - Dm)·(Vh - Vm) / (Vjth - Vm)…(4)

[0074] (Case 2) When the value of the learning flag XDm during traffic jam driving is "0" (that is, when the learned vehicle speed Vm and the preferred inter-vehicle distance Dm during traffic jam driving are not in the learned state and are cleared) Dtgt = D0 + (DJth - D0)·(Vh / VJth) …(5)

[0075] On the other hand, when the vehicle speed Vh of the host vehicle is higher than the traffic jam driving determination vehicle speed VJth, the CPU determines "No" in step 710 and proceeds to step 730 to perform the processing described below. Thereafter, the CPU proceeds to step 795 and temporarily ends this routine. Note that in this case, the target inter-vehicle distance Dtgt is set to the product of the target inter-vehicle time Ttgt and the vehicle speed Vh of the host vehicle.

[0076] The CPU sets the value of the traffic jam flag XJ to "0." The CPU sets the value of the stop learning flag XD0 to "0." The stop learning flag XD0 is set to "1" when the stop suitable inter-vehicle distance D0 is calculated (learned) (see step 980 in FIG. 9, which will be described later). The CPU sets the value of the traffic jam learning flag XDm to "0." The CPU sets the value of the suitable inter-vehicle distance D0 when stopped stored in the look-up table M1 to an initial value D0int. The CPU clears each of the "learned vehicle speed Vm and the optimum inter-vehicle distance Dm when driving in a traffic jam" stored in the lookup table M1.

[0077] 4. Learning the optimum inter-vehicle distance Dm and learning vehicle speed Vm during traffic congestion Next, a method for learning the suitable inter-vehicle distance Dm and learned vehicle speed Vm when traveling in traffic congestion, which are stored in lookup table M1 (see step 720 in FIG. 7), will be described. At a predetermined timing, the CPU starts processing from step 800 in FIG. 8, and determines whether the value of the ACC execution flag XACC is "1" in step 810. If the value of the ACC execution flag XACC is "1," the CPU proceeds to step 820 and determines whether the value of the traffic congestion execution flag XJ is "1."

[0078] If the value of the traffic jam driving flag XJ is "1", the CPU determines "Yes" in step 820 and proceeds to step 830 to determine whether the value of the traffic jam driving learning flag XDm is "0". In other words, the CPU determines whether the value of the traffic jam driving suitable inter-vehicle distance Dm has been learned since the host vehicle HV became caught in the current traffic jam (since the host vehicle speed Vh became equal to or less than the traffic jam driving judgment vehicle speed VJth).

[0079] If the value of the traffic jam driving learning flag XDm is "0," the CPU proceeds to step 840 and determines whether the host vehicle speed Vh is greater than the "positive extremely low speed determination value VLth" (i.e., the host vehicle HV is not stopped) and less than the "traffic jam driving determination vehicle speed VJth." If the determination condition of step 840 is met, the CPU proceeds from step 840 to step 850 and obtains an obtainable distance from among the inter-vehicle distances to other vehicles while driving in a traffic jam (see inter-vehicle distances D1 to D5 illustrated in FIG. 3) based on the "camera object information or fusion object information."

[0080] Next, the CPU proceeds to step 860 and determines whether two or more of the acquired inter-vehicle distances during traffic congestion are valid. That is, the CPU determines whether the vehicle model of the other vehicle located behind the host vehicle HV in the direction of travel across the inter-vehicle distance during traffic congestion is a predetermined vehicle model (large vehicles such as trucks and buses, and motorcycles, etc.) different from the vehicle model of the host vehicle HV (i.e., a passenger car). If the vehicle model of the other vehicle is determined to be a predetermined vehicle model, the CPU determines that the inter-vehicle distance during traffic congestion is invalid. Furthermore, the CPU determines whether the vehicle model of the other vehicle traveling immediately behind the host vehicle HV is a predetermined vehicle model different from the vehicle model of the host vehicle HV. If the other vehicle is determined to be a predetermined vehicle model different from the vehicle model of the host vehicle HV, the CPU determines that the inter-vehicle distance between the other vehicle and the host vehicle is invalid as the "inter-vehicle distance during traffic congestion."

[0081] If two or more valid "distances between other vehicles while traveling in a traffic jam" are acquired, the CPU learns the optimum inter-vehicle distance Dm while traveling in a traffic jam and the learned vehicle speed Vm by performing the "processing of steps 870 to 890" described below. After that, the CPU proceeds to step 895 and temporarily ends this routine.

[0082] Step 870: The CPU learns the average value of the obtained valid "inter-vehicle distances while traveling in a traffic jam" as the optimum inter-vehicle distance Dm while traveling in a traffic jam (that is, stores it in an appropriate location in the look-up table M1). Step 880: The CPU stores the current vehicle speed Vh as the learned vehicle speed Vm (that is, stores it in an appropriate location in the look-up table M1). Step 890: The CPU sets the value of the traffic jam learning flag XDm to “1”.

[0083] If the CPU determines "No" in any of steps 810 to 840, or if it determines "No" in step 860, it proceeds directly from the step where it determined "No" to step 895.

[0084] 5. Learning the optimal distance D0 when stopping Next, a method for learning the stop-time suitable inter-vehicle distance D0 stored in the lookup table M1 (see step 720 in FIG. 7) will be described. At a predetermined timing, the CPU starts processing from step 900 in FIG. 9, and determines in step 910 whether the value of the ACC execution flag XACC is "1." If the value of the ACC execution flag XACC is "1," the CPU proceeds to step 920 and determines whether the value of the traffic jam driving flag XJ is "1."

[0085] If the value of the traffic jam driving flag XJ is "1", the CPU determines "Yes" in step 920 and proceeds to step 930 to determine whether the value of the stop-time learning flag XD0 is "0". In other words, the CPU determines whether the value of the stop-time suitable inter-vehicle distance D0 has been learned since the host vehicle HV became caught in the current traffic jam (since the host vehicle speed Vh became equal to or less than the traffic jam driving judgment vehicle speed VJth).

[0086] If the value of the suitable inter-vehicle distance D0 when stopping is "0", the CPU proceeds to step 940 and determines whether the current vehicle speed Vh is equal to or greater than "0" and equal to or less than the positive extremely low speed determination value VLth. Note that the CPU may also determine in step 940 whether the vehicle speed Vh is "0".

[0087] If the judgment condition of step 940 is met, the CPU proceeds from step 940 to step 950 and obtains the obtainable distance from the inter-vehicle distances to other vehicles when stopped as described above (see inter-vehicle distances D11 to D15 illustrated in Figure 4) based on the "camera object information or fusion object information."

[0088] Next, the CPU proceeds to step 960 and determines whether two or more of the acquired inter-vehicle distances at the time of stopping are valid. That is, the CPU determines whether the vehicle type of the other vehicle stopped behind the host vehicle HV in the direction of travel, across the inter-vehicle distance at the time of stopping, is a predetermined vehicle type (large vehicles such as trucks and buses, and motorcycles, etc.) different from the vehicle type of the host vehicle HV (i.e., a passenger car), and if it is determined that the other vehicle type is a predetermined vehicle type, it determines that the inter-vehicle distance at the time of stopping is invalid. Furthermore, the CPU determines whether the vehicle type of the other vehicle stopped immediately behind the host vehicle HV is a predetermined vehicle type different from the vehicle type of the host vehicle HV, and if it is determined that the other vehicle is a predetermined vehicle type different from the vehicle type of the host vehicle HV, it determines that the inter-vehicle distance between the other vehicle and the host vehicle is invalid as the "inter-vehicle distance at the time of stopping."

[0089] If two or more valid "inter-vehicle distances when stopped" are acquired, the CPU learns the preferable inter-vehicle distance when stopped D0 by performing the "processing of steps 970 and 980" described below. After that, the CPU proceeds to step 995 and temporarily ends this routine.

[0090] Step 970: The CPU learns the average value of the acquired valid "inter-vehicle distances when stopped" as the optimal inter-vehicle distance when stopped D0 (that is, stores it in an appropriate location in the look-up table M1). Step 980: The CPU sets the value of the stop learning flag XD0 to "1."

[0091] If the CPU determines "No" in any of steps 910 to 940, or if it determines "No" in step 960, it proceeds directly to step 995 from the step where it determined "No."

[0092] 6. Adjusting the distance between vehicles when stopped At a predetermined timing, the CPU starts processing from step 1000 in Fig. 10, and determines whether the value of the ACC execution flag XACC is "1" in step 1010. If the value of the ACC execution flag XACC is "1", the CPU proceeds to step 1020 and determines whether the value of the traffic jam driving flag XJ is "1".

[0093] If the value of the traffic jam flag XJ is "1", the CPU judges "Yes" in step 1020 and proceeds to step 1030 to determine whether the host vehicle speed Vh is "0" (i.e., whether the host vehicle HV is stopped).

[0094] If the host vehicle speed Vh is "0", the CPU determines "Yes" in step 1030 and proceeds to step 1035, where it determines whether the value of the ACC permission flag XALW is "1". If the value of the ACC permission flag XALW is "1", the CPU determines "Yes" in step 1035 and proceeds to step 1040, where it determines whether the current time is before "the time when a predetermined waiting time has elapsed since the time when the host vehicle speed Vh changed from a value greater than "0" to "0" (i.e., the stop time)". If the current time is between the stop time and the time when the waiting time has elapsed since the stop time, the CPU proceeds from step 1040 to step 1050, where it determines whether the value of the stop-time learning flag XD0 is "1".

[0095] If the value of the stop learning flag XD0 is "1" (i.e., the value of the stop suitable inter-vehicle distance D0 has been learned), the CPU judges "Yes" in step 1050 and proceeds to step 1060, where it determines whether the current inter-vehicle distance (actual inter-vehicle distance) Dact is greater than the "learned stop suitable inter-vehicle distance D0."

[0096] If the current inter-vehicle distance Dact is greater than the "learned preferred inter-vehicle distance D0 when stopped," the CPU determines "Yes" in step 1060 and proceeds to step 1070, where it causes the host vehicle HV to creep. This causes the host vehicle HV to move forward at an extremely slow speed. Next, the CPU proceeds to step 1080, where it determines whether the inter-vehicle distance Dact is equal to or less than the "learned preferred inter-vehicle distance D0 when stopped."

[0097] If the host vehicle inter-vehicle distance Dact is not equal to or less than the "learned preferred inter-vehicle distance D0 when stopping," the CPU returns from step 1080 to step 1070 and causes the host vehicle HV to creep. As a result, the host vehicle inter-vehicle distance Dact approaches the "learned preferred inter-vehicle distance D0 when stopping." By repeating this process, if the host vehicle inter-vehicle distance Dact matches the "learned preferred inter-vehicle distance D0 when stopping," the CPU determines "Yes" in step 1080 and proceeds to step 1085.

[0098] In step 1085, the CPU stores the host vehicle inter-vehicle distance Dact as the actual stop inter-vehicle distance Dstp. Next, the CPU proceeds to step 1090 and sets the value of the ACC permission flag XALW to "0." At this time, the CPU sends an instruction to the brake ECU 50 to increase the braking force. That is, the CPU performs brake holding control. After that, the CPU proceeds to step 1095 and temporarily ends this routine.

[0099] When the CPU proceeds to step 1050, if the value of the stop learning flag XD0 is not "1" (i.e., the value of the stop-time suitable inter-vehicle distance D0 has not been learned), the CPU determines "No" in step 1050 and proceeds directly to step 1095. Furthermore, when the CPU proceeds to step 1060, if the current inter-vehicle distance Dact is equal to or less than the learned "stop-time suitable inter-vehicle distance D0," the CPU determines "No" in step 1060 and proceeds directly to step 1085. In addition, when the CPU proceeds to step 1040, if the current time is after the time when the standby time has elapsed since the stop time, the CPU determines "No" in step 1040 and proceeds directly to step 1085.

[0100] Furthermore, if the CPU determines "No" in any of steps 1010 to 1035, it proceeds directly to step 1095 from the step where it determined "No".

[0101] 7. ACC start control (start control when vehicle speed is "0") At a predetermined timing, the CPU starts processing from step 1100 in Fig. 11, and determines whether the value of the ACC execution flag XACC is "1" in step 1110. If the value of the ACC execution flag XACC is "1," the CPU determines "Yes" in step 1110 and proceeds to step 1120, where it determines whether the value of the traffic jam driving flag XJ is "1."

[0102] If the value of the traffic jam driving flag XJ is "1", the CPU determines "Yes" in step 1120 and proceeds to step 1130 to determine whether the host vehicle speed Vh is "0". If the host vehicle speed Vh is "0", the CPU determines "Yes" in step 1130 and proceeds to step 1140 to determine whether the value of the ACC permission flag XALW is "0".

[0103] If the value of the ACC permission flag XALW is "0", the CPU determines "Yes" in step 1140 and proceeds to step 1150 to determine whether the host vehicle inter-vehicle distance Dact is greater than the "value obtained by adding the actual stopping vehicle inter-vehicle distance Dstp to the threshold distance Dth". If the preceding vehicle PV starts moving after the preceding vehicle PV and the host vehicle HV have stopped, the host vehicle inter-vehicle distance Dact becomes greater than the "value obtained by adding the actual stopping vehicle inter-vehicle distance Dstp to the threshold distance Dth".

[0104] In this case, the CPU determines "Yes" in step 1150 and proceeds to step 1160 to determine whether or not the driver has performed a start operation. More specifically, the CPU determines that the driver has performed a start operation when a request to resume ACC is issued as a result of the driver performing a predetermined operation on the ACC operation switch 31, or when the accelerator pedal is operated and the accelerator pedal operation amount AP changes from "0" to a value greater than "0."

[0105] If the driver has performed a start operation, the CPU determines "Yes" in step 1160, proceeds to step 1170, and sets the value of the ACC permission flag XALW to "1." As a result, the CPU determines "Yes" in step 530 of Fig. 5, and the host vehicle is started by the processing of steps 580 and 590. Thereafter, the CPU proceeds to step 1195 and temporarily ends this routine.

[0106] If the CPU determines "No" in any of steps 1110 to 1160, it proceeds directly to step 1195 from the step where it determined "No."

[0107] As explained above, the control device DS: The distance between a first other vehicle stopped around the host vehicle and a second other vehicle stopped just before the first other vehicle (see D12 to D15 in FIG. 4), and The distance between the first other vehicle stopped around the subject vehicle and the subject vehicle stopped just before the first other vehicle (see D11 in FIG. 4), is obtained as the distance between other vehicles when stopped.

[0108] Furthermore, the control device DS sets the preferable inter-vehicle distance D0 when the host vehicle is stopped, which is used as the target inter-vehicle distance Dtgt when the host vehicle is stopped, in accordance with the "obtained inter-vehicle distance when the host vehicle is stopped." Therefore, the target inter-vehicle distance when the host vehicle is stopped can be controlled to a preferable distance.

[0109] Furthermore, if the acquired inter-vehicle distance when the vehicle is stopped is a predetermined vehicle type (a vehicle type different from the vehicle's own vehicle), the inter-vehicle distance when the vehicle is stopped is not considered valid and is not reflected in the preferred inter-vehicle distance when the vehicle is stopped D0. Therefore, the target inter-vehicle distance when the vehicle is stopped can be controlled to a more preferred distance.

[0110] The present invention is not limited to the above-described embodiment and modifications, and various modifications can be adopted within the scope of the present invention. For example, the control device DS can be applied to an autonomous vehicle in a state where the driving mode has transitioned from autonomous driving to driving by a driver.

[0111] Furthermore, as long as information about objects around the host vehicle (a 360-degree range centered on the host vehicle) can be obtained, any number of camera devices may be used, and a LiDAR may be installed instead of or in addition to a radar device. Furthermore, the control device DS may determine the suitable inter-vehicle distance D0 when stopping based only on the inter-vehicle distance D11 maintained between the host vehicle HV and another vehicle stopped immediately behind the stopped host vehicle HV. In this case, the control device DS may set the suitable inter-vehicle distance D0 when stopping to the inter-vehicle distance D11, or may set the suitable inter-vehicle distance D0 when stopping to "a value obtained by adding a predetermined margin distance to the inter-vehicle distance D11." [Explanation of symbols]

[0112] 10...Driver assistance ECU, 40...Powertrain ECU, 50...Brake ECU.

Claims

1. an information acquisition device that acquires information about objects present around the vehicle; a controller capable of performing inter-vehicle distance control that acquires an inter-vehicle distance between the host vehicle and a preceding vehicle located immediately in front of the host vehicle based on the information, and controls the host vehicle so that the acquired inter-vehicle distance is maintained at a predetermined target inter-vehicle distance; In a vehicle distance control device equipped with The controller acquires, based on the information, an inter-vehicle distance between a first other vehicle stopped in the vicinity of the subject vehicle and a second other vehicle stopped immediately before the first other vehicle or the subject vehicle stopped immediately before the first other vehicle, as an inter-vehicle distance when stopped; The vehicle is configured to use a suitable inter-vehicle distance when stopped, which is set according to the acquired inter-vehicle distance when stopped, as the target inter-vehicle distance when the vehicle is stopped. Vehicle distance control device.

2. 2. The inter-vehicle distance control device according to claim 1, The controller The system is configured to determine whether the first other vehicle is a predetermined vehicle type based on the information, and when it is determined that the first other vehicle is the predetermined vehicle type, not to reflect in the preferred following distance when stopped the following distance between the first other vehicle determined to be the predetermined vehicle type and the second other vehicle stopped just before the first other vehicle, and the following distance between the first other vehicle determined to be the predetermined vehicle type and the vehicle itself stopped just before the first other vehicle. Vehicle distance control device.

3. 2. The inter-vehicle distance control device according to claim 1, The controller When the vehicle speed of the vehicle becomes higher than a predetermined traffic jam travel determination vehicle speed, the preferable inter-vehicle distance when stopped is returned to an initial value; Thereafter, if the preferred inter-vehicle distance when stopped is reset before a predetermined waiting period has elapsed since the host vehicle was stopped after being decelerated by the inter-vehicle distance control, the host vehicle is moved forward so that the inter-vehicle distance matches the reset preferred inter-vehicle distance when stopped. It was configured as follows: Vehicle distance control device.

4. 4. The inter-vehicle distance control device according to claim 3, The controller When the host vehicle speed, which is the vehicle speed of the host vehicle, drops from a speed higher than a predetermined traffic congestion determination vehicle speed to a speed equal to or lower than the traffic congestion determination vehicle speed during execution of the inter-vehicle distance control, the inter-vehicle distance between a third other vehicle traveling around the host vehicle and a fourth other vehicle traveling just before the third other vehicle or the host vehicle traveling just before the third other vehicle is acquired as the inter-vehicle distance during traffic congestion based on the information, The vehicle speed at the time when the vehicle-to-vehicle distance during the traffic jam is acquired is stored as a learned vehicle speed; calculating an appropriate inter-vehicle distance during traffic congestion based on the acquired inter-vehicle distance during traffic congestion; storing the optimum inter-vehicle distance during traffic congestion in association with the learned vehicle speed; When the vehicle speed is lower than the learned vehicle speed, the target inter-vehicle distance is determined based on the suitable inter-vehicle distance when stopped, the suitable inter-vehicle distance during traffic congestion, the learned vehicle speed, and the vehicle speed. Vehicle distance control device.

5. 1. A method for controlling a host vehicle so that a host vehicle inter-vehicle distance, which is a distance between the host vehicle and a preceding vehicle located immediately in front of the host vehicle, is maintained at a predetermined target inter-vehicle distance, acquiring a distance between a first other vehicle stopped in the vicinity of the subject vehicle and a second other vehicle stopped immediately before the first other vehicle or the subject vehicle stopped immediately before the first other vehicle as a distance between the other vehicles when stopped; calculating a suitable inter-vehicle distance when stopping based on the acquired inter-vehicle distance when stopping; a step of using the preferred inter-vehicle distance when the host vehicle is stopped as the target inter-vehicle distance when the host vehicle is stopped; Including, Vehicle distance control method.

6. A program to be executed by a computer installed in a vehicle, The program is written to the computer. controlling the host vehicle so that a host vehicle inter-vehicle distance, which is a distance between the host vehicle and a preceding vehicle located immediately in front of the host vehicle, is maintained at a predetermined target inter-vehicle distance; acquiring a distance between a first other vehicle stopped in the vicinity of the subject vehicle and a second other vehicle stopped immediately before the first other vehicle or the subject vehicle stopped immediately before the first other vehicle as a distance between the other vehicles when stopped; calculating a suitable inter-vehicle distance when stopping based on the acquired inter-vehicle distance when stopping; a step of using the preferred inter-vehicle distance when the host vehicle is stopped as the target inter-vehicle distance when the host vehicle is stopped; Execute program.

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