Driving assistance device, vehicle, travel control method, and program

Abstract

A driving assistance device includes a camera device that acquires a camera image by capturing a prescribed area in front of a host vehicle, and a control unit that causes the host vehicle to travel in a manner that an acceleration of the host vehicle coincides with a following acceleration for causing a vehicle-to-vehicle distance between a preceding vehicle traveling in front of the host vehicle and the host vehicle to coincide with a target vehicle-to-vehicle distance. The control unit is configured to, in a case where the preceding vehicle is a large vehicle, acquire the target vehicle-to-vehicle distance for causing a signal lamp distance to be longer than a parking necessary distance, the signal lamp distance indicating a distance from the host vehicle to a signal lamp when a signal lamp of a prescribed height is detected above the preceding vehicle in the camera image, and the parking necessary distance indicating a distance traveled by the host vehicle until the host vehicle stops in a case where the host vehicle is assumed to decelerate at a prescribed deceleration.

Description

Technical Field

[0001] The present invention relates to a driving assistance device that performs follow control, which enables the vehicle to move in such a way that the inter-vehicle distance between the vehicle and a preceding vehicle traveling in front of the vehicle is consistent with a target inter-vehicle distance. Background Technology

[0002] Driving assistance devices that perform follow control have been known for a long time. For example, the driving assistance device described in Patent Document 1 (hereinafter referred to as "the first prior art device") decelerates by using an appropriate deceleration that is coordinated with the driver's senses in order to maintain the inter-vehicle distance between the vehicle and the vehicle in front of it greater than the final target distance.

[0003] The driving assistance device described in Patent Document 2 (hereinafter referred to as "the second prior art device") performs deceleration control in order to stop in front of a traffic light when the traffic light displays a stop signal.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2009-149167

[0007] Patent Document 2: Japanese Patent Application Publication No. 2011-154619 Summary of the Invention

[0008] Assume the second existing device performs follow control like the first existing device. If the vehicle ahead is a large vehicle (truck, bus, etc.), the traffic light may be obstructed by it. Therefore, the distance to the traffic light may be shorter when the second existing device first detects it, requiring a larger deceleration control. This larger deceleration control may cause anxiety for the driver.

[0009] The present invention was made to solve the aforementioned problems. That is, one of the objectives of the present invention is to provide a driving assistance device that prevents the vehicle from decelerating at a large deceleration that would cause discomfort to the occupants of the vehicle in order to slow down in front of a stop signal light (stop signal light).

[0010] The driving assistance device of the present invention (hereinafter also referred to as "the device of the present invention") comprises:

[0011] Camera device (22), which acquires camera images by photographing a designated area in front of the vehicle; and

[0012] Control units (20, 30, 36, 40, 44) drive the vehicle in such a manner that the acceleration of the vehicle is consistent with the following acceleration, the following acceleration being used to make the inter-vehicle distance between the vehicle and the preceding vehicle traveling in front of the vehicle consistent with the target inter-vehicle distance.

[0013] The control unit is configured to,

[0014] If the preceding vehicle is a large vehicle ("Yes" in step 510), the target inter-vehicle distance is set to a large vehicle inter-vehicle distance that makes the traffic light distance longer than the necessary stopping distance. The traffic light distance represents the distance from the vehicle to the traffic light when a traffic light at a predetermined height is detected above the preceding vehicle in the camera image. The necessary stopping distance represents the distance the vehicle has traveled before coming to a stop, assuming the vehicle decelerates at a predetermined rate (step 530).

[0015] The vehicle is driven in such a manner that the acceleration of the vehicle is consistent with the following acceleration (step 455).

[0016] In a situation where the longer the distance between the vehicle and the preceding vehicle (which is a large vehicle), the longer the distance to the traffic light, the traffic light is detected above the preceding vehicle in the camera image. According to the device of the present invention, when the preceding vehicle is a large vehicle, the target distance is set as a large vehicle distance, and the vehicle travels in a manner that makes the distance between the vehicles match the target distance. The large vehicle distance is used to ensure that the distance to the traffic light detected above the preceding vehicle in the camera image is longer than the distance necessary to stop. Therefore, when a stop light is detected, the vehicle can stop before the stop light by decelerating at a predetermined rate. Thus, it is possible to prevent the vehicle from decelerating at a large rate that would cause discomfort to the occupants of the vehicle in order to stop before the stop light.

[0017] In one embodiment of the apparatus of the present invention, the control unit is configured to, when the preceding vehicle is a large vehicle, obtain the target vehicle distance (referring to the vehicle speed) when the vehicle speed, representing the speed of the current vehicle, is above a predetermined speed (Vsd) in such a way that the target vehicle-to-vehicle distance is longer than when the preceding vehicle is not a large vehicle. Figure 3 ).

[0018] As described above, when the preceding vehicle is a large vehicle, a target inter-vehicle distance is obtained to make the signal light distance longer than the necessary stopping distance. The higher the vehicle's speed, the longer the necessary stopping distance; the lower the vehicle's speed, the shorter the necessary stopping distance. Therefore, when the vehicle's speed is above a predetermined speed, the target inter-vehicle distance becomes longer when the preceding vehicle is a large vehicle than when the preceding vehicle is not a large vehicle.

[0019] In one embodiment of the apparatus of the present invention, the control unit is configured to,

[0020] If the preceding vehicle is not a large vehicle ("No" in step 510), the target workshop distance is set to a normal workshop distance, which is a workshop distance that increases with the vehicle's speed within a predetermined range (step 515).

[0021] If the preceding vehicle is a large vehicle ("Yes" in step 510), the target workshop distance is set to the longer of the normal workshop distance and the workshop distance for large vehicles (steps 535 to 545).

[0022] According to this method, when the vehicle speed is less than the prescribed speed, it can prevent the vehicle from getting too close to the vehicle in front, and reduce the possibility of causing anxiety to the occupants of the vehicle.

[0023] In one embodiment of the device of the present invention, the control unit is configured to obtain the large vehicle workshop distance by multiplying the necessary parking distance by a predetermined constant (step 530, equation (4)).

[0024] Furthermore, the constant is set as follows: the value (H2) obtained by subtracting the pre-set camera height (Hca) representing the height of the camera device from the pre-set large vehicle height (Hlv) representing the height of the large vehicle, and dividing the value (H1) obtained by subtracting the camera height from the pre-set signal light height (Htr) representing the height of the signal light (Equation (4)).

[0025] According to this method, a large vehicle inter-vehicle distance can be reliably obtained such that the distance at which the traffic light is detected above the preceding vehicle is longer than the necessary stopping distance. This reduces the likelihood of situations where the vehicle must decelerate significantly to stop in front of a stop signal (hereinafter referred to as "abrupt deceleration situation").

[0026] In the above manner, the control unit is configured to obtain the large vehicle vehicle distance in the following manner: the large vehicle vehicle distance varies according to the square of the vehicle speed, which represents the speed of the vehicle, and the greater the vehicle speed, the longer the large vehicle vehicle distance (step 530, equation (4)). Figure 3 ).

[0027] As described above, the parking distance for large vehicles is set to be longer than the distance obtained by multiplying the necessary stopping distance by a constant. The necessary stopping distance, as shown in equation (3) below, is a value that varies with the square of the vehicle speed, becoming longer as the vehicle speed increases. Therefore, the parking distance for large vehicles also varies in this way. According to this method, the parking distance for large vehicles can be reliably obtained in a way that makes the distance to the traffic light when it is detected above the preceding vehicle longer than the necessary stopping distance, thus reducing the possibility of the aforementioned sudden deceleration situation.

[0028] In one embodiment of the device of the present invention, the control unit is configured to, when the traffic light displays a stop signal, if the distance to the traffic light becomes less than or equal to a starting distance obtained by adding a predetermined distance to the necessary stopping distance ("Yes" in step 465), then drive the vehicle in such a manner that the acceleration of the vehicle is consistent with the smaller of the following acceleration and the deceleration for stopping the vehicle in front of the traffic light (steps 445, 450, 475).

[0029] According to this method, if the distance to the traffic light becomes less than or equal to the starting distance, the vehicle will travel in a manner that matches the smaller of its acceleration, following acceleration, and deceleration. Therefore, the vehicle can be brought to a stop in front of a stop signal displaying a stop signal. Furthermore, even if a vehicle ahead decelerates sharply in front of a stop signal, the vehicle can maintain a target distance between itself and the vehicle ahead while decelerating.

[0030] In one embodiment of the device of the present invention, the control unit is configured as follows:

[0031] If the preceding vehicle is not the large vehicle ("No" in step 510), the normal vehicle-to-vehicle distance is obtained as the target vehicle-to-vehicle distance. The normal vehicle-to-vehicle distance is a distance that is longer as the vehicle speed increases within a predetermined range (steps 505 and 515).

[0032] If the vehicle other than the preceding vehicle that is within a predetermined distance from the present vehicle in the direction of travel forward is the large vehicle (in step 705, "Yes"),

[0033] The control unit obtains the normal workshop distance and the large vehicle workshop distance (steps 505 and 710), and,

[0034] If the first distance deviation obtained by subtracting the normal workshop distance from the workshop distance is less than the second distance deviation obtained by subtracting the workshop distance for the large vehicle from the workshop distance between the vehicle and the large vehicle ("Yes" in step 725), then the control unit sets the target workshop distance to the normal workshop distance (step 515).

[0035] If the first distance deviation is greater than or equal to the second distance deviation ("No" in step 725), then the control unit sets the target workshop distance to the large vehicle workshop distance (step 730).

[0036] According to this method, even when the vehicle other than the preceding vehicle is a large vehicle, the vehicle can travel at a distance such that the distance from the traffic light when it is detected in the camera image above the large vehicle other than the preceding vehicle is longer than the distance necessary to stop. Therefore, the possibility of abrupt deceleration can be reduced.

[0037] The vehicle of the present invention is equipped with the device of the present invention described above.

[0038] The driving control method of the present invention is a method for driving a vehicle in such a way that the acceleration of the vehicle itself is consistent with the following acceleration, wherein the following acceleration is used to make the inter-vehicle distance between the vehicle traveling in front of the vehicle consistent with the target inter-vehicle distance.

[0039] The driving control method includes:

[0040] In the first step (step 530), if the preceding vehicle is a large vehicle ("Yes" in step 510), the target inter-vehicle distance is set to a large vehicle inter-vehicle distance that makes the traffic light distance longer than the necessary stopping distance. The traffic light distance represents the distance from the vehicle to the traffic light when a traffic light at a predetermined height is detected above the preceding vehicle, as seen in a camera image obtained by a camera device (22) mounted on the vehicle and capturing a predetermined area in front of the vehicle. The necessary stopping distance represents the distance the vehicle has traveled before stopping, assuming the vehicle decelerates at a predetermined rate.

[0041] The second step (step 455) is to move the vehicle in such a way that the acceleration of the vehicle is consistent with the following acceleration.

[0042] The procedure of this invention is applied to a vehicle, and the vehicle is driven in such a manner that the vehicle's acceleration is consistent with a following acceleration, the following acceleration being used to make the inter-vehicle distance between the vehicle and a preceding vehicle traveling in front of the vehicle consistent with a target inter-vehicle distance.

[0043] The program causes the computer in the vehicle to perform a process comprising the following steps:

[0044] In the first step (step 530), if the preceding vehicle is a large vehicle ("Yes" in step 510), the target vehicle-to-vehicle distance is set to a vehicle-to-vehicle distance where the traffic light distance is longer than the stopping distance. The traffic light distance represents the distance from the vehicle to the traffic light when a traffic light at a predetermined height is detected above the preceding vehicle, as seen in a camera image obtained by a camera device (22) capturing a predetermined area in front of the vehicle. The stopping distance represents the distance the vehicle travels before coming to a stop, assuming the vehicle decelerates at a predetermined rate.

[0045] The second step (step 455) is to move the vehicle in such a way that the vehicle's acceleration is consistent with the following acceleration.

[0046] Based on the aforementioned driving control method and procedure, when a stop light is detected, the vehicle can be brought to a stop near the stop light by decelerating at a predetermined rate. Therefore, it prevents the vehicle from decelerating at an excessive rate that would cause discomfort to the occupants in order to stop near a stop light.

[0047] Furthermore, the apparatus of the present invention can be expressed as follows.

[0048] The device of the present invention comprises:

[0049] Camera device (22), which acquires camera images by photographing a designated area in front of the vehicle; and

[0050] Control units (20, 30, 36, 40, 44) are configured to drive the vehicle in a manner that makes the inter-vehicle distance between the vehicle and a preceding vehicle traveling in front of it consistent with the target inter-vehicle distance.

[0051] The control unit is configured such that, when the preceding vehicle is a large vehicle, the target vehicle distance is longer when the vehicle speed (Vsd), which indicates the speed of the current vehicle, is above a predetermined speed (Vsd), than when the preceding vehicle is not a large vehicle.

[0052] Furthermore, in the foregoing description, to aid in understanding the invention, the names and / or reference numerals used in the embodiments described below are enclosed in parentheses to represent the components of the invention. However, the constituent elements of the invention are not limited to the embodiments specified by the names and / or reference numerals. Attached Figure Description

[0053] Figure 1 This is a schematic system configuration diagram of a driving assistance device according to an embodiment of the present invention.

[0054] Figure 2 This is a diagram used to illustrate the second inter-vehicle distance obtained when the preceding vehicle is a large vehicle.

[0055] Figure 3 It is a graph showing the relationship between the distances to the first and second workshops and the vehicle speed.

[0056] Figure 4 It is shown Figure 1 The flowchart shown is of the ACC routine executed by the CPU of the driver assistance ECU.

[0057] Figure 5 It is shown Figure 1 The flowchart shown is a subroutine for obtaining the following acceleration, executed by the CPU of the driving assistance ECU.

[0058] Figure 6 This is an explanatory diagram illustrating a first modified embodiment of the present invention.

[0059] Figure 7 This is a flowchart of a portion of the following acceleration acquisition subroutine executed by the CPU of a driving assistance ECU, illustrating a first variation of an embodiment of the present invention. Detailed Implementation

[0060] <Composition>

[0061] like Figure 1 As shown, the driving assistance device (hereinafter referred to as "this assistance device") 10 according to the embodiments of the present invention is mounted on a vehicle (hereinafter referred to as "this vehicle") VA.

[0062] This auxiliary device 10 includes a driving assistance ECU 20, an engine ECU 30, and a brake ECU 40. Hereinafter, the driving assistance ECU 20 will be referred to as "DSECU 20".

[0063] These ECUs are Electronic Control Units (ECUs) with a microcomputer as their main component, sometimes referred to as "controllers" or "computers." The microcomputer includes a CPU, ROM, RAM, and interfaces (I / F). These ECUs are interconnected via CAN (Controller Area Network) to exchange data. The CPU performs various functions by executing commands (programs, routines) stored in the ROM. Some or all of these ECUs can be integrated into a single ECU.

[0064] This auxiliary device 10 includes a wheel speed sensor 21, a camera device 22, and a millimeter-wave radar device 23. They are connected to the DSECU 20 for exchanging data.

[0065] Wheel speed sensors 21 are provided for each wheel of the vehicle VA. Each wheel speed sensor 21 generates a wheel pulse signal whenever the corresponding wheel rotates by a predetermined angle. The DSECU 20 counts the number of pulses per unit time of the wheel pulse signals received from each wheel speed sensor 21 and obtains the rotational speed of each wheel based on the number of pulses. Furthermore, the DSECU 20 obtains the vehicle speed Vs, which represents the speed of the vehicle VA, based on the wheel speed of each wheel. As an example, the DSECU 20 obtains the average wheel speed of the four wheels as the vehicle speed Vs.

[0066] Camera device 22 is disposed in the upper center of the front window inside the passenger compartment of vehicle VA, and acquires an image (hereinafter also referred to as "camera image") of a predetermined area in front of vehicle VA. Based on the camera image, camera device 22 acquires object information and white line information, and sends the camera object information containing this information to DSECU 20. The object information includes the distance to an object existing in the aforementioned predetermined area and the direction of that object. The white line information includes the position of the right and left white lines of the lane currently being traveled by vehicle VA relative to vehicle VA.

[0067] The millimeter-wave radar device 23 transmits millimeter waves in front of the vehicle VA. The millimeter-wave radar device 23 is a known sensor that detects objects by receiving millimeter waves (reflected waves) reflected from them. Based on the received reflected waves, the millimeter-wave radar device 23 calculates the distance to the object (object distance), the relative velocity of the object relative to the vehicle VA (object relative velocity) Vr, and the direction of the object. Furthermore, the millimeter-wave radar device 23 transmits "radar object information containing object distance, object relative velocity Vr, and object direction" to the DSECU 20 at predetermined intervals.

[0068] The DSECU 20 determines the position of an object in front of the vehicle VA relative to the vehicle VA based on the object information from the camera and the object information from the radar.

[0069] The engine ECU 30 is connected to the accelerator pedal operation sensor 32 and the engine sensor 34, and receives the detection signals from these sensors.

[0070] The accelerator pedal operation amount sensor 32 detects the operation amount (i.e., accelerator pedal operation amount AP) of the accelerator pedal 32a in the vehicle VA. The accelerator pedal operation amount AP is "0" when the driver does not operate the accelerator pedal 32a.

[0071] Engine sensor 34 is a sensor that detects the operating status of the internal combustion engine (not shown) that serves as the drive source for the vehicle's VA. Engine sensor 34 includes a throttle opening sensor, an engine speed sensor, and an intake air volume sensor, among others.

[0072] Furthermore, the engine ECU 30 is connected to engine actuators 36, such as the throttle actuator and fuel injection valve. The engine ECU 30 adjusts the driving force of the vehicle's VA by driving the engine actuators 36 to change the torque produced by the internal combustion engine.

[0073] The engine ECU 30 determines the target throttle opening TAtgt in such a way that the greater the accelerator pedal operation amount AP, the greater the target throttle opening TAtgt. The engine ECU 30 drives the throttle actuator in a manner that makes the throttle opening match the target throttle opening TAtgt.

[0074] The brake ECU 40 is connected to the wheel speed sensor 21 and the brake pedal operation sensor 42, and receives the detection signals from these sensors.

[0075] The brake pedal operation amount sensor 42 detects the operation amount (i.e., brake pedal operation amount BP) of the brake pedal 42a of the vehicle VA. When the brake pedal 42a is not operated, the brake pedal operation amount BP is "0".

[0076] The braking ECU 40 obtains the vehicle speed Vs based on the wheel pulse signal from the wheel speed sensor 21, just like the DSECU 20. Alternatively, the braking ECU 40 can also obtain the vehicle speed Vs from the DSECU 20.

[0077] Furthermore, the brake ECU 40 is connected to the brake actuator 44. The brake actuator 44 is a hydraulically controlled actuator. The brake actuator 44 is disposed in a hydraulic circuit (not shown) between a master cylinder that pressurizes the actuating fluid by the force of the brake pedal 42a and a known friction braking device including wheel cylinders disposed on each wheel. The brake actuator 44 adjusts the hydraulic pressure supplied to the wheel cylinders to adjust the braking force of the vehicle VA.

[0078] The brake ECU 40 determines a "target acceleration that is negative" based on the brake pedal operation amount BP. The brake ECU 40 drives the brake actuator 44 in a manner that makes the actual acceleration of the vehicle VA match the target acceleration.

[0079] (ACC)

[0080] The DSECU 20 performs ACC (Adaptive Cruise Control). ACC includes both cruise control and follow control.

[0081] Cruise control is performed when there is no preceding vehicle VB traveling in front of the vehicle VA. It maintains the vehicle speed Vs at a preset speed Vset set by the driver of the vehicle VA while driving the vehicle VA. In detail, the DSECU 20 drives the vehicle VA in a manner that matches the acceleration G of the vehicle VA with a target acceleration that makes the vehicle speed Vs match the preset speed Vset.

[0082] Follow control is performed in the presence of a preceding vehicle VB. It is a control mechanism that moves vehicle VA by following the preceding vehicle while maintaining a distance D between VB and the current vehicle VA that matches the "first distance D1," which is longer as the vehicle speed Vs increases within a specified distance Dset. Specifically, DSECU 20 moves vehicle VA by ensuring that the acceleration G matches the "target acceleration used to maintain the distance D at the first distance D1." The first distance D1 is sometimes referred to as the "normal distance."

[0083] The target acceleration obtained in constant speed control or follow-up control is called "ACC target acceleration Gacc".

[0084] In either cruise control or follow control, the vehicle VA can be driven without the driver operating the accelerator pedal 32a and the brake pedal 42a.

[0085] Furthermore, during ACC execution, the DSECU 20 determines, based on camera images, whether a stop signal light (TR) is present in front of the vehicle's VA. A stop signal light (TR) is a light that indicates a stop, such as a light with either red or yellow light colors.

[0086] When a stop light TR is present and the distance Dtr from the stop light TR to the stop light TR is less than or equal to the "starting distance Ds" (described later), the DSECU 20 obtains a predetermined deceleration Gdec as the target acceleration Gtr for stopping. Then, the DSECU 20 moves the vehicle VA in a manner that makes the acceleration G consistent with the smaller of the "ACC target acceleration and the stopping target acceleration Gtr". Thus, the vehicle VA stops just before the stop light TR.

[0087] The deceleration Gdec is set to a deceleration rate (e.g., -2.0 m / s²) that will not cause discomfort to the occupants of the vehicle's VA. 2 ).

[0088] The initial distance Ds is the distance obtained by adding the required stopping distance Dn to the specified distance Dp. The required stopping distance Dn is the distance traveled by vehicle VA before its speed Vs reaches 0 km / h (i.e., before vehicle VA stops) while the vehicle VA decelerates at the aforementioned deceleration rate Gdec.

[0089] (A summary of the action)

[0090] Assume that this auxiliary device 10 performs follow control by following the preceding vehicle VB, which is a large vehicle. Furthermore, the large vehicle is likely to have a large vehicle height Hlv (see below). Figure 2 The vehicles in question are trucks and buses, etc. In this situation, the following situation may sometimes occur: because the traffic light TR in front of the vehicle VA is blocked by a large vehicle, the camera device 22 is unable to photograph the traffic light TR when the distance between the traffic light and Dtr is relatively long, and can only photograph the traffic light TR when the distance between the traffic light and Dtr becomes relatively short.

[0091] In this situation, it is possible that when the auxiliary device 10 first detects the stop light TR, the distance from the stop light TR to the stop light Dtr is much shorter than the initial distance Ds. Furthermore, even if the vehicle VA decelerates at the aforementioned deceleration Gdec from the moment the distance from the stop light TR to the stop light Dtr is much shorter than the initial distance Ds, it may not be able to stop in front of the stop light TR. In this case, a deceleration greater than the aforementioned deceleration Gdec is required to decelerate the vehicle VA, but such a large deceleration is likely to cause discomfort to the occupants.

[0092] Here, when the preceding vehicle VB is a large vehicle, the auxiliary device 10 obtains a second inter-vehicle distance D2. This second inter-vehicle distance D2 is the inter-vehicle distance at which the signal light distance Dtr when the "signal light TR at the prescribed signal light height Htr" is first detected above the large vehicle becomes the starting distance Ds (i.e., the signal light distance Dtr is longer than the necessary stopping distance Dn). Then, the auxiliary device 10 drives the vehicle VA in a manner that makes the inter-vehicle distance D consistent with the second inter-vehicle distance D2. In addition, the second inter-vehicle distance D2 is sometimes referred to as the "inter-vehicle distance for large vehicles".

[0093] Therefore, when the preceding vehicle VB is a large vehicle, if the auxiliary device 10 begins to decelerate at the aforementioned deceleration rate Gdec upon first detecting the stop light TR, it can bring the vehicle VA to a stop just before the stop light TR. Thus, the vehicle VA can be brought to a stop just before the stop light TR without causing discomfort to the occupants of the vehicle VA due to the large deceleration.

[0094] (action)

[0095] Reference Figure 2 The distance from the second workshop to D2 is explained in detail above.

[0096] Figure 2 The camera height Hca, large vehicle height Hlv, and signal light height Htr shown are preset values, preset to "1m", "3m", and "5m" respectively. Camera height Hca is the height of camera device 22, large vehicle height Hlv is the height of the large vehicle, and signal light height Htr is the height of signal light Tr.

[0097] like Figure 2 As shown, right triangle T1 and right triangle T2 contained in right triangle T1 are similar.

[0098] Right triangle T1 is a triangle with a side of length Dtr (the distance from the traffic light) and a side of length H1 (the height of the camera after subtracting the height Hca from the height Htr of the traffic light).

[0099] Right triangle T2 is a triangle with a side of length D2, which is the distance between the second workshop and the other side of length H2, which is the height H2 obtained by subtracting the camera height Hca from the height Hlv of the large vehicle.

[0100] Based on the above similarity relationship, the distance D2 of the second workshop can be expressed by the signal light distance Dtr as shown in equation (1).

[0101] [Formula 1]

[0102]

[0103] Here, the time required for the vehicle speed Vs to reach “0km / h” before deceleration with deceleration Gdec, i.e. the necessary time to stop, can be expressed by the following formula (2).

[0104] T=Vs / Gdec……(2)

[0105] Furthermore, the necessary stopping distance Dn traveled by the vehicle VA during the aforementioned stopping time T at a deceleration rate Gdec can be expressed by the following equation (3) using the vehicle speed Vs at the start of deceleration.

[0106] [Formula 2]

[0107]

[0108] If we substitute the signal light distance Dtr in the above equation (1) into the "starting distance Ds obtained by adding the specified distance Dp to the necessary parking distance Dn", then the second workshop distance D2 can be expressed by the following equation (4).

[0109] [Formula 3]

[0110]

[0111] In the above equation (4), the height H1, height H2, deceleration Gdec, and specified distance Dp are fixed values ​​that are set in advance. Therefore, the second workshop distance D2 is represented by a quadratic function with the vehicle speed Vs as the variable.

[0112] This auxiliary device 10 performs follow-up control in a manner that makes the inter-vehicle distance D between the vehicle and the preceding vehicle VB (which is a large vehicle) consistent with the aforementioned second inter-vehicle distance D2. Therefore, the starting distance Dtr at the moment when the stop signal light TR is first detected above the preceding vehicle VB becomes the starting distance Ds. Thus, even if signal deceleration control begins from that moment, thereby starting to decelerate at a deceleration rate Gdec, the vehicle VA can be brought to a stop before the stop signal light TR.

[0113] The relationship between the distances D1 and D2 between the first and second workshops and the vehicle speed Vs is as follows: Figure 3 The graph is shown below.

[0114] Within the specified distance Dset (=20m) from the designated workshop, the greater the vehicle speed Vs, the longer the distance D1 from the first workshop.

[0115] As shown in equation (4) above, the distance D2 between the second workshops varies depending on the value of the square of the vehicle speed Vs. The greater the vehicle speed Vs, the longer the distance D2.

[0116] Since the higher the vehicle speed Vs, the longer the necessary stopping distance Dn, when the vehicle speed Vs becomes above the specified speed Vsd, the initial distance Ds (i.e., the distance to the second workshop D2) is longer than the distance to the first workshop D1.

[0117] A lookup table specifying the relationship between the first inter-vehicle distance D1 and the vehicle speed Vs is pre-stored in the ROM. Alternatively, a lookup table specifying the relationship between the second inter-vehicle distance D2 and the vehicle speed Vs can be pre-stored in the ROM, and the second inter-vehicle distance D2 can be obtained each time by applying the vehicle speed Vs to equation (4).

[0118] (Specific actions)

[0119] <ACC Routine>

[0120] The CPU of DSECU 20 (hereinafter, unless otherwise specified, "CPU" refers to the CPU of DSECU 20) executes at predetermined intervals. Figure 4 The flowchart shows the ACC routine.

[0121] Therefore, when the specified time is reached, the CPU starts from... Figure 4 The process begins at step 400 and proceeds to step 405. In step 405, the CPU determines whether the value of the ACC flag Xacc is "1".

[0122] The ACC flag Xacc is set to "1" when the specified ACC start condition is met, and set to "0" when the specified ACC end condition is met. Additionally, the ACC flag Xacc is also set to "0" in the initial routine. The initial routine is executed by the CPU when the ignition / key / switch (not shown) of the vehicle's VA changes from the off position to the on position.

[0123] The ACC start condition is the condition that is met when the ACC start switch (not shown) is operated.

[0124] The ACC termination condition is the condition that is met when the ACC termination switch (not shown) is operated.

[0125] If the value of the ACC identifier Xacc is "0", the CPU determines "no" in step 405, proceeds to step 495, and temporarily terminates this routine.

[0126] If the value of the ACC identifier Xacc is "1", the CPU determines "yes" in step 405 and executes steps 410 to 420 in sequence.

[0127] Step 410: The CPU obtains camera object information from the camera device 22.

[0128] Step 415: The CPU obtains radar object information from the millimeter-wave radar device 23.

[0129] Step 420: The CPU determines whether the stop signal light TR is in front of the vehicle VA based on the camera image.

[0130] If the stop signal light TR is not present, the CPU determines "no" in step 420 and executes steps 425 and 430 in sequence.

[0131] Step 425: The CPU sets the parking target acceleration Gtr to infinity.

[0132] Step 430: The CPU determines whether there is a forward vehicle VB based on the camera object information and radar object information.

[0133] If there is no preceding vehicle VB, the CPU determines "no" in step 430 and executes steps 435 to 445 sequentially.

[0134] Step 435: The CPU obtains the vehicle speed deviation ΔVs by subtracting the current vehicle speed Vs from the set vehicle speed Vset.

[0135] Step 440: The CPU obtains the ACC target acceleration Gacc by applying the vehicle speed deviation ΔVs to the following equation (5).

[0136] Gacc=k1×ΔVs……(5)

[0137] In equation (5) above, k1 is the specified gain (coefficient).

[0138] Step 445: The CPU determines whether the ACC target acceleration Gacc is less than the parking target acceleration Gtr.

[0139] Here, in the absence of a stop signal light TR, since the target acceleration for stopping, Gtr, is set to infinity as described above (refer to step 425), the target acceleration for ACC, Gacc, is less than the target acceleration for stopping, Gtr. Therefore, the CPU determines "yes" in step 445 and executes steps 450 and 455 sequentially.

[0140] Step 450: The CPU sets the target acceleration Gtgt to the ACC target acceleration Gacc.

[0141] Step 455: The CPU sends acceleration / deceleration commands containing the target acceleration Gtgt to the engine ECU 30 and brake ECU 40.

[0142] After this, the CPU proceeds to step 495, temporarily terminating this routine.

[0143] Upon receiving an acceleration or deceleration command, the engine ECU 30 controls the engine actuator 36 in a manner that makes the acceleration G of the vehicle VA consistent with the target acceleration Gtgt contained in the acceleration or deceleration command.

[0144] Upon receiving an acceleration or deceleration command, the braking ECU 40 controls the braking actuator 44 in a manner that makes the acceleration G of the vehicle VA consistent with the target acceleration Gtgt contained in the acceleration or deceleration command.

[0145] In addition, the acceleration G of this vehicle VA is obtained by differentiating the vehicle speed Vs over time.

[0146] On the other hand, if the stop signal lamp TR is present when the CPU enters step 420, the CPU determines "yes" in step 420 and executes steps 460 and 465 in sequence.

[0147] Step 460: The CPU obtains the necessary parking distance Dn by applying the vehicle speed Vs to the above equation (3).

[0148] Step 465: The CPU determines whether the signal light distance Dtr obtained from the camera image is below the starting distance Ds.

[0149] If the distance from the traffic light to Dtr is longer than the starting distance to Ds, the CPU determines "No" in step 465 and sets the target acceleration Gtr to infinity in step 425. After this, the CPU proceeds to the processing after step 430.

[0150] If the distance from the traffic light to Dtr is less than the starting distance Ds, the CPU determines "yes" in step 465 and proceeds to step 470. In step 470, the CPU sets the target acceleration Gtr to the aforementioned deceleration Gdec and proceeds to step 430.

[0151] If there is no preceding vehicle VB, the CPU determines "No" in step 430 and executes steps 435 and 440 sequentially to obtain the ACC target acceleration Gacc. If the ACC target acceleration Gacc is greater than or equal to the parking target acceleration Gtr (i.e., if the parking target acceleration Gtr is less than or equal to the ACC target acceleration Gacc), the CPU determines "No" in step 445 and proceeds to step 475. In step 475, the CPU sets the target acceleration Gtgt to the parking target acceleration Gtr. After this, the CPU proceeds to step 455, sends acceleration / deceleration commands, proceeds to step 495, and temporarily terminates this routine.

[0152] On the other hand, if there is a preceding vehicle VB when the CPU enters step 430, the CPU determines "yes" in step 430 and proceeds to step 480. In step 480, the CPU executes... Figure 5 The flowchart shown illustrates the acceleration acquisition subroutine. In the acceleration acquisition subroutine, the CPU acquires the target acceleration Gtgt to make the target shop distance Dtgt equal to either the first shop distance D1 or the second shop distance D2. After executing the acceleration acquisition subroutine in step 480, the CPU proceeds to processing steps 445 and beyond.

[0153] <Subroutine for obtaining acceleration>

[0154] CPU enters Figure 4 After step 480 as shown, from Figure 5 The process begins with step 500, and steps 505 and 510 are executed sequentially.

[0155] Step 505: The CPU obtains the first inter-vehicle distance D1 by applying the vehicle speed Vs to a lookup table that defines the relationship between the first inter-vehicle distance D1 and the vehicle speed Vs.

[0156] Step 510: The CPU determines whether the vehicle VB in front is a large vehicle based on the camera image.

[0157] More specifically, if the ratio of vertical pixels to horizontal pixels (aspect ratio) of the preceding vehicle VB in the camera image is above a threshold, the CPU determines that the preceding vehicle VB is a large vehicle. Alternatively, at least one image of a large vehicle (registered image) can be pre-stored in the ROM. The CPU obtains the similarity between the image of the preceding vehicle VB in the camera image and the registered image. If the similarity is above the threshold, the preceding vehicle VB is determined to be a large vehicle.

[0158] If the preceding vehicle VB is not a large vehicle, the CPU determines "no" in step 510 and executes steps 515 to 525 sequentially.

[0159] Step 515: The CPU sets the target workshop distance Dtgt to the first workshop distance D1.

[0160] Step 520: The CPU obtains the distance deviation ΔD by subtracting the target shop distance Dtgt from the shop distance D.

[0161] Step 525: The CPU obtains the ACC target acceleration Gacc by applying the distance deviation ΔD and the relative velocity of the object Vr to equation (6).

[0162] Gacc=ka1×(k2×ΔD+k3×Vr)……(6)

[0163] In equation (6) above, ka1, k2 and k3 are the specified gains (coefficients).

[0164] After this, the CPU proceeds to step 595, temporarily terminating the current routine and entering... Figure 4 Step 445 is shown.

[0165] If the preceding vehicle VB is determined to be a large vehicle when the CPU enters step 510, the CPU determines "yes" in step 510 and executes steps 530 and 535 in sequence.

[0166] Step 530: The CPU obtains the second inter-vehicle distance D2 by applying the vehicle speed Vs to the above formula (4).

[0167] Step 535: The CPU determines whether the distance D1 between the first workshop and the second workshop is greater than the distance D2 between the two workshops.

[0168] If the distance D1 between the first workshop and the second workshop is greater than the distance D2 between the second workshop and the first workshop, the CPU determines "yes" in step 535 and proceeds to step 540. In step 540, the CPU sets the target workshop distance Dtgt to the distance D1 between the first workshop and the second workshop.

[0169] On the other hand, if the distance D1 from the first workshop is less than or equal to the distance D2 from the second workshop, the CPU determines "No" in step 535 and proceeds to step 545. In step 545, the CPU sets the target workshop distance Dtgt to the distance D2 from the second workshop.

[0170] After executing step 540 or 545, the CPU executes steps 520 and 525 to obtain the ACC target acceleration Gacc. After this, the CPU proceeds to step 595, temporarily terminating the current routine and entering... Figure 4 Step 445 is shown.

[0171] According to this embodiment, when the preceding vehicle VB is a large vehicle, the vehicle VA travels in a manner that makes the longer of the inter-vehicle distance D and the first inter-vehicle distance D1 and the second inter-vehicle distance D2 expressed by the above equation (4) consistent. As a result, the distance Dtr of the stop signal light TR when it is first detected above the preceding vehicle VB, which is a large vehicle, is greater than or equal to the starting distance Ds. Therefore, even without decelerating at a large rate, the vehicle VA can be stopped close to the stop signal light TR.

[0172] The present invention is not limited to the above embodiments, and various modifications can be adopted within the scope of the present invention.

[0173] (First variation)

[0174] Reference Figure 6This section provides a summary of the actions in this variation.

[0175] According to the DSECU 20 involved in this variant, even if the preceding vehicle VB is not a large vehicle, if a large vehicle exists within a specified distance Dth from the front of the current vehicle VA, the DSECU 20 obtains a first inter-vehicle distance D1 and a second inter-vehicle distance D2. Figure 6 In the example shown, it is assumed that the preceding vehicle VC traveling in front of the preceding vehicle VB is a large vehicle. The DSECU 20 obtains a first distance deviation ΔDa, which is the distance between the current vehicle VA and the preceding vehicle VB minus a first inter-vehicle distance D1, and a second distance deviation ΔDb, which is the distance between the current vehicle VA and the preceding vehicle VC minus a second inter-vehicle distance D'. Furthermore, if the first distance deviation ΔDa is less than the second distance deviation ΔDb, the DSECU 20 sets the target inter-vehicle distance Dtgt to the first inter-vehicle distance D1; if the first distance deviation ΔDa is greater than or equal to the second distance deviation ΔDb, the DSECU 20 sets the target inter-vehicle distance Dtgt to the second inter-vehicle distance D2.

[0176] exist Figure 6 In the example shown, since the workshop distance D is longer than the first workshop distance D1, the first distance deviation ΔDa is positive. Since the workshop distance D' is shorter than the second workshop distance D2, the second distance deviation ΔDb is negative. Therefore, the first distance deviation ΔDa is greater than the second distance deviation ΔDb, and thus, DSECU 20 sets the target workshop distance Dtgt to the second workshop distance D2.

[0177] Even if the vehicle in front is not a large vehicle, if a large vehicle is present within the specified distance Dth, the DSECU 20 may fail to detect the stop light TR due to the large vehicle's presence at a relatively long distance Dtr. According to this modified example, even in this case, since the distance from the stop light TR to Dtr when it is first detected is greater than the starting distance Ds, the vehicle VA can be brought to a stop near the stop light TR by deceleration at the aforementioned deceleration Gdec.

[0178] exist Figure 5 If the determination in step 510 is "no" (i.e., if the preceding vehicle VB is not a large vehicle), the CPU of the DSECU 20 involved in this variant enters... Figure 7 Step 705 is shown. In step 705, the CPU determines whether a large vehicle exists in the area within a predetermined distance Dth from the front end of the vehicle VA towards the front.

[0179] In the absence of a large vehicle, the CPU determines "no" in step 705 and proceeds to... Figure 5 Step 515, as shown, sets the target workshop distance Dtgt to the first workshop distance D1, and executes the following steps sequentially. Figure 5 Steps 520 and 525 are shown.

[0180] On the other hand, in the presence of large vehicles, the CPU in Figure 7 If the determination in step 705 is "yes", then steps 710 to 725 are executed sequentially.

[0181] Step 710: The CPU obtains the second inter-vehicle distance D2 by applying the vehicle speed Vs to the above formula (4).

[0182] Step 715: The CPU obtains the first distance deviation ΔDa by subtracting the first workshop distance D1 from the workshop distance D.

[0183] Step 720: The CPU obtains the second distance deviation ΔDb by subtracting the second workshop distance D2 from the workshop distance D'.

[0184] Step 725: The CPU determines whether the first distance deviation ΔDa is less than the second distance deviation ΔDb.

[0185] If the first distance deviation ΔDa is less than the second distance deviation ΔDb, the CPU determines "yes" in step 725 and proceeds to... Figure 5 Step 515, as shown, sets the target workshop distance Dtgt to the first workshop distance D1. After this, the CPU executes sequentially... Figure 5 Steps 520 and 525 are shown.

[0186] On the other hand, if the first distance deviation ΔDa is greater than or equal to the second distance deviation ΔDb, the CPU determines "No" in step 725 and executes steps 730 and 735 in sequence.

[0187] Step 730: The CPU sets the target workshop distance Dtgt to the second workshop distance D2.

[0188] Step 735: The CPU obtains the ACC target acceleration Gacc by applying the above-mentioned second distance deviation ΔDb and the object relative velocity Vr to equation (7).

[0189] Gacc=ka1×(k2×ΔDb+k3×Vr)……(7)

[0190] The difference between equation (7) and equation (6) is that the second distance deviation ΔDb is used instead of the distance deviation ΔD in equation (6).

[0191] After executing step 735, the CPU enters... Figure 5Step 595, as shown, temporarily terminates this routine and proceeds to... Figure 4 Step 445 is shown.

[0192] (Second variation)

[0193] In the above embodiment, when the distance Dtr from the stop signal light TR to the stop signal light is less than or equal to the starting distance Ds, the DSECU 20 sets the target parking acceleration Gtr to a predetermined deceleration Gdec. In this variation, when the vehicle VA reaches a position a predetermined distance ahead of the stop signal light TR, the DSECU 20 obtains the acceleration required for the vehicle VA to stop and sets the target parking acceleration Gtr to that acceleration.

[0194] Even when the target acceleration Gtr for stopping is achieved as in this variant example, since the vehicle VA moves the vehicle so that the distance Dtr from the stop light TR when it first detects the stop light TR becomes a distance D from the vehicle to the vehicle at a distance D greater than the starting distance Ds, it is possible to stop near the stop light TR without decelerating at a large speed.

[0195] (Third variation)

[0196] In the above implementation, the CPU determines whether other vehicles besides its own vehicle are large vehicles based on camera images, but other information can also be used in determining whether a vehicle is a large vehicle. An example is given below.

[0197] This vehicle (VA) can also obtain information from other vehicles, which is used to determine whether it is a large vehicle, by communicating with other vehicles within the communication range specified by this vehicle (VA).

[0198] For example, the above information represents model information of other vehicles. The ROM of DSECU 20 pre-stores large vehicle model information that has been registered. The CPU of DSECU 20 obtains the model information and the vehicle's location information through vehicle-to-vehicle communication. If the model information is registered in the large vehicle model information, then the vehicle is determined to be a large vehicle.

[0199] (Fourth variation)

[0200] The millimeter-wave radar device 23 can be any remote sensing device capable of detecting objects by transmitting a wireless medium instead of transmitting millimeter waves and receiving the reflected wireless medium.

[0201] (Fifth variation)

[0202] This auxiliary device 10 can be applied not only to the aforementioned engine vehicles, but also to hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), fuel cell electric vehicles (FCEV), and electric vehicles (BEV).

[0203] The present invention can also be understood as a non-temporary storage medium that stores a program for implementing the functions of the above-mentioned driving assistance device 10 and is computer-readable.

[0204] [Explanation of the labels]

[0205] 10: Driving assistance device; 20: Driving assistance ECU; 22: Camera device; 30: Engine ECU; 36: Engine actuator; 40: Brake ECU; 44: Brake actuator.

Claims

1. A driving assistance device, comprising: A camera device, mounted on the front windshield inside the passenger compartment of the vehicle, acquires images of a predetermined area in front of the vehicle by photographing the area; and A control unit that moves the vehicle in a manner that matches the vehicle's acceleration with a following acceleration, the following acceleration being used to match the inter-vehicle distance between the vehicle and a preceding vehicle traveling in front of it with a target inter-vehicle distance. The control unit is configured to, If the preceding vehicle is not a large vehicle, the target inter-vehicle distance is set to a typical inter-vehicle distance. This typical inter-vehicle distance is a distance that increases with the vehicle's speed, which is a predetermined range from the set inter-vehicle distance. When the preceding vehicle is a large vehicle, the target workshop distance is set to the longer of the normal workshop distance and the workshop distance for large vehicles. The workshop distance for large vehicles is a distance greater than or equal to the distance obtained by multiplying the necessary parking distance by a preset constant. The necessary parking distance represents the distance the vehicle travels before coming to a stop, assuming the vehicle decelerates at a predetermined rate. The constant is set as follows: the value obtained by subtracting a preset camera height (representing the camera device's height) from a preset large vehicle height (representing the large vehicle's height), and dividing that value by subtracting the camera height from a preset signal light height (representing the signal light's height). The vehicle is driven in such a manner that the acceleration of the vehicle is consistent with the following acceleration.

2. The driving assistance device according to claim 1, wherein, The control unit is configured to obtain the large vehicle vehicle distance in such a way that the large vehicle vehicle distance varies according to the square of the vehicle speed, which represents the speed of the vehicle, and the greater the vehicle speed, the longer the large vehicle vehicle distance.

3. The driving assistance device according to claim 1, wherein, The control unit is configured to, when the traffic light displays a stop signal, if the traffic light distance is below a starting distance obtained by adding a predetermined distance to the necessary stopping distance, drive the vehicle in such a manner that the vehicle's acceleration is consistent with the smaller of the following acceleration and the deceleration used to bring the vehicle to a stop in front of the traffic light, wherein the traffic light distance represents the distance from the vehicle to the traffic light when the traffic light is detected at a predetermined height above the preceding vehicle in the camera image.

4. The driving assistance device according to any one of claims 1 to 3, wherein, The control unit is configured as follows: If the preceding vehicle is not the large vehicle, the typical inter-vehicle distance is taken as the target inter-vehicle distance. The typical inter-vehicle distance is a distance that is longer than the predetermined inter-vehicle distance, where the vehicle speed (representing the vehicle's speed) is greater. If the vehicle other than the preceding vehicle, which is within a predetermined distance from the present vehicle and moving forward, is the large vehicle... The control unit obtains the normal workshop distance and the large vehicle workshop distance, and, If the first distance deviation obtained by subtracting the normal workshop distance from the workshop distance is less than the second distance deviation obtained by subtracting the workshop distance for the large vehicle from the workshop distance between the vehicle and the large vehicle, then the control unit sets the target workshop distance to the normal workshop distance; If the first distance deviation is greater than or equal to the second distance deviation, the control unit sets the target workshop distance as the large vehicle workshop distance.

5. A vehicle equipped with a driving assistance device according to any one of claims 1 to 4.

6. A driving control method comprising a computer equipped with the vehicle to drive the vehicle in a manner that makes the vehicle's acceleration consistent with a following acceleration, wherein the following acceleration is used to make the inter-vehicle distance between the vehicle and a preceding vehicle traveling in front of the vehicle consistent with a target inter-vehicle distance. The driving control method includes the following steps performed by the computer: The first step, when the preceding vehicle is not a large vehicle, is to set the target workshop distance to a normal workshop distance, which is a workshop distance that increases with the vehicle's speed (representing its speed) within a predetermined range. When the preceding vehicle is a large vehicle, the target workshop distance is set to the longer of the normal workshop distance and the workshop distance for large vehicles. The workshop distance for large vehicles is the distance obtained by multiplying the necessary stopping distance by a predetermined constant. The necessary stopping distance represents the distance traveled by the vehicle before it comes to a stop, assuming it decelerates at a predetermined rate. The constant is set as follows: the value obtained by subtracting a predetermined camera height (representing the camera device's height) from a predetermined large vehicle height (representing the large vehicle's height), divided by the value obtained by subtracting the camera height from a predetermined signal light height (representing the signal light's height). The camera device is mounted on the front windshield inside the vehicle's passenger compartment and acquires images of a predetermined area in front of the vehicle. The second step is to move the vehicle in a manner that makes the acceleration of the vehicle match the following acceleration.

7. A non-volatile storage medium storing a program for a vehicle, the program, via a computer equipped with the vehicle, causing the vehicle to move in a manner that matches the vehicle's acceleration with a following acceleration, the following acceleration being used to match the inter-vehicle distance between the vehicle and a preceding vehicle traveling in front of it with a target inter-vehicle distance. The program causes the computer to perform a process comprising the following steps: The first step, when the preceding vehicle is not a large vehicle, is to set the target workshop distance to a normal workshop distance, which is a workshop distance that increases with the vehicle's speed (indicating its speed) within a predetermined range. When the preceding vehicle is a large vehicle, the target workshop distance is set to the longer of the normal workshop distance and the workshop distance for large vehicles. The workshop distance for large vehicles is the distance obtained by multiplying the necessary stopping distance by a predetermined constant. The necessary stopping distance represents the distance the vehicle travels before coming to a stop, assuming the vehicle decelerates at a predetermined rate. The constant is set as follows: the value obtained by subtracting a predetermined camera height (indicating the height of the camera device) from a predetermined large vehicle height (indicating the height of the large vehicle), divided by the value obtained by subtracting the camera height from a predetermined signal light height (indicating the height of the signal light). The camera device is mounted on the front windshield inside the vehicle's passenger compartment and acquires images of a predetermined area in front of the vehicle. The second step is to move the vehicle in a manner that makes the vehicle's acceleration consistent with the following acceleration.

Images