JP2008213581A - Driving support method for vehicle and driving support device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving support method of a vehicle and a driving support device of a vehicle for optimally supporting driving according to different conditions when the vehicle collides with a following vehicle having different conditions. <P>SOLUTION: When determined that rear-end collision with a following vehicle cannot be avoided while rear-end collision with a preceding vehicle may occur even under acceleration control, a CPU 2 calculates acceleration to prevent collision with the preceding vehicle while accepting collision with the following vehicle with the minimum impact force, in consideration of the speed of the rear vehicle and the speed of the own vehicle as well as the vehicle weight of the own vehicle and the vehicle weight of the following vehicle. Then, the CPU 2 controls the acceleration of the own vehicle by the calculated acceleration through a fuel injection controller 15. Therefore, the own vehicle can absorb rear-end collision with the minimum impact force irrespective of the model of the following vehicle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle driving support method and a vehicle driving support device.

2. Description of the Related Art Conventionally, a collision impact reducing device that reduces the impact in consideration of rear-end collision from the rear of the host vehicle has been proposed (for example, Patent Document 1). In Patent Document 1, the host vehicle is accelerated immediately before the rear-end collision, the relative speed with the rear-end vehicle is reduced, and the impact is reduced.
JP 2005-113760 A

  However, the above apparatus only considers only the relative speed, and is not a reduction method that takes into consideration the weight of the host vehicle other than the vehicle speed, the weight of the opponent vehicle, and the road condition ahead. In other words, considering only the relative speed, the acceleration control is uniquely determined with respect to the relative speed, and therefore, it has not been possible to expect an optimal impact reduction according to different circumstances from time to time.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide driving assistance for a vehicle that can provide optimum driving assistance according to the different conditions for rear-end collision of a rear vehicle having different conditions. A method and a driving support apparatus for a vehicle are provided.

  The invention according to claim 1 is a vehicle for acquiring approach information of the rear vehicle and host vehicle traveling information of the host vehicle, judging whether or not the rear vehicle has collided, and avoiding the rear impact or mitigating the impact caused by the rear impact. The vehicle driving support method for obtaining the weight of the host vehicle and the weight of the rear vehicle, and determining that a rear-end collision cannot be avoided based on the approach information and the host vehicle travel information. On the basis of the weight of the host vehicle and the weight of the rear vehicle in addition to the host vehicle travel information, travel change information for changing the travel state of the host vehicle for shock reduction is obtained, and based on the obtained travel change information To control the traveling of the vehicle.

A second aspect of the present invention is the vehicle driving support method according to the first aspect,
Further, obstacle information in front of the host vehicle is acquired, and the travel change information is obtained based on the obstacle information in addition to the approach information, the host vehicle travel information, the weight of the host vehicle, and the weight of the rear vehicle. And the vehicle is controlled to travel based on the obtained travel change information.

  According to a third aspect of the present invention, in the driving support method for a vehicle according to the second aspect, road surface information ahead of the host vehicle is acquired, the approach information, the host vehicle travel information, the weight of the host vehicle, The travel change information is obtained based on the road surface information in addition to the weight of the rear vehicle and the obstacle information, and the own vehicle is travel-controlled based on the obtained travel change state.

The invention according to claim 4 is based on approach information acquisition means for acquiring approach information of the rear vehicle, host vehicle travel information acquisition means for acquiring host vehicle travel information of the host vehicle, the approach information and the host vehicle travel information. Determining the presence or absence of a rear-end collision of the rear vehicle, and when the determination means determines that the rear-end collision cannot be avoided, obtains the travel change information of the own vehicle for avoiding the rear-end collision or reducing the impact caused by the rear-end collision. A vehicle driving support apparatus comprising: a change information calculating means; and a travel control means for drivingly controlling the own vehicle driving means based on the changed travel information, the storage means storing the weight of the own vehicle; Rear vehicle weight acquisition means for acquiring the weight of the rear vehicle, and when the determination means determines that rear-end collision cannot be avoided, the change information calculation means includes the approach information and the host vehicle travel information. In addition, based on the weight of the weight and the rear vehicle of the own vehicle, determine the travel change information.

  A fifth aspect of the present invention is the vehicle driving support device according to the fourth aspect, further comprising obstacle information acquisition means for acquiring obstacle information ahead of the host vehicle, wherein the change information calculation means is the approach information. The travel change information is obtained based on the road information in addition to the host vehicle travel information, the weight of the host vehicle, and the weight of the rear vehicle.

  A sixth aspect of the present invention is the vehicle driving support apparatus according to the fifth aspect, further comprising road surface information acquisition means for acquiring road surface information of the road surface ahead of the host vehicle, wherein the change information calculation means includes the approach information, the own vehicle The travel change information is obtained based on the road surface information in addition to the vehicle travel information, the weight of the host vehicle, the weight of the rear vehicle, and the obstacle information.

  According to the first aspect of the invention, in addition to the approach information and the own vehicle travel information, the travel change information is created by taking into consideration the inherent weight of the host vehicle and the inherent weight of the rear vehicle. Therefore, it is possible to provide optimum driving assistance for shock mitigation according to the weight of the rear vehicle that varies from time to time.

  According to the invention of claim 2, since the travel change information further includes the obstacle information ahead of the host vehicle, the optimum driving support for shock mitigation while avoiding the obstacle ahead of the host vehicle. Can do.

  According to the invention of claim 3, since the road change information further includes the road surface information in front of the host vehicle, for example, an obstacle in front of the host vehicle is avoided in consideration of the state of the road surface being driven. It is possible to provide optimal driving assistance for shock mitigation.

  According to the fourth aspect of the invention, the travel change information is created by taking into account the inherent weight of the host vehicle and the inherent weight of the rear vehicle in addition to the approach information and the host vehicle travel information. Therefore, it is possible to provide optimum driving assistance for shock mitigation according to the weight of the rear vehicle that varies from time to time.

  According to the invention of claim 5, since the travel change information further includes obstacle information ahead of the host vehicle, optimal driving support for shock mitigation while avoiding the obstacle ahead of the host vehicle. Can do.

  According to the invention of claim 6, since the travel change information further includes road surface information of the road ahead of the host vehicle, for example, an obstacle in front of the host vehicle is considered in consideration of the state of the road surface during travel. It is possible to provide optimal driving assistance for shock mitigation while avoiding.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a vehicle driving support device according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating a configuration of a driving support device mounted on a car (own vehicle).

  1 includes a determination unit that performs main control, a change information calculation unit, a CPU 2 as a weight acquisition unit of the host vehicle, a RAM 3 as a storage unit that temporarily stores calculation results of the CPU 2, and a route guidance program. A ROM 4 is provided for storing various driving support programs such as a rear-end impact mitigation support program. Also. The driving support device 1 includes a GPS receiving unit 5 and a vehicle side sensor input I / F unit 6.

  The CPU 2 is connected to the GPS receiver 5 and calculates absolute coordinates based on the position detection signal input from the GPS receiver 5. Further, the CPU 2 inputs a vehicle speed pulse signal and a direction detection signal from the vehicle speed sensor 6a and the gyro 6b provided in the host vehicle C1 (see FIG. 2) via the vehicle side sensor input I / F unit 6. The relative coordinates from the reference position are calculated by autonomous navigation. Then, the CPU 2 specifies the own vehicle position together with the absolute coordinates based on the GPS receiver 5. The XY coordinate system for vehicles is a coordinate system (road surface coordinates) for indicating the position of the host vehicle C1 on the road surface. The CPU 2 updates and stores the road surface coordinate value of the vehicle position at that time in a predetermined storage area of the RAM 3. Further, the CPU 2 calculates the vehicle speed V1 of the host vehicle C1 at that time as host vehicle travel information based on the vehicle speed pulse signal from the vehicle speed sensor 6a serving as host vehicle travel information acquisition means.

  The vehicle-side sensor input I / F unit 6 is connected to a steering sensor 6c and an ignition switch 6d provided in the host vehicle C1. The CPU 2 inputs a steering angle signal from the steering sensor 6c via the vehicle side sensor input I / F unit 6, and calculates the steering angle at that time.

  Furthermore, the vehicle side sensor input I / F unit 6 is connected to a rear millimeter wave radar 6e, a front millimeter wave radar 6f, and a road surface detection sensor 6g provided in the host vehicle C1. As shown in FIG. 2, the rear millimeter wave radar 6e as the approach information acquisition unit is attached to the center position of the rear end of the host vehicle C1, and emits a millimeter wave backward from the rear end of the host vehicle C1. The rear vehicle C2 approaching from the rear is detected. The CPU 2 inputs a radar signal from the rear millimeter wave radar 6e via the vehicle-side sensor input I / F unit 6, and the rear as the approach information of the rear vehicle C2 approaching based on the radar signal. The vehicle speed V2 of the vehicle C2 and the distance (inter-vehicle distance) D1 from the host vehicle C1 to the rear vehicle C2 are calculated.

  The CPU 2 determines whether or not there is a collision of the rear vehicle C2 based on the vehicle speed V2 of the rear vehicle C2, the inter-vehicle distance D1 from the host vehicle C1 to the rear vehicle C2, and the vehicle speed V1 of the host vehicle C1.

  In this embodiment, CPU2 calculates | requires 1st rear-end collision time Tx1 (= D1 / Vs) from the inter-vehicle distance D1 and relative speed Vs1 (= V2-V1), 1st rear-end collision expected time Tx1 and a driver | operator's driving operation It is compared with the first response time Td1 required for avoidance by. Then, it is determined whether or not a collision can be avoided by comparing the first expected rear-end collision time Tx1 and the first response time Td1 (Td1 <Tx1). During the first response time Td1, the driver operates and the brake control device 14 and the fuel injection control device are controlled based on the operation, so that the vehicle and the brake for avoiding the vehicle C1 reach the target drive amount and travel. Is the time until the process is executed, which is obtained in advance through experiments and tests. Therefore, the first response time Td1 occupies a large weight as a whole when the operation response time of the driver is added. The first response time Td1 is stored in the ROM 4. The first response time Td1 is stored in the ROM 4.

Incidentally, when the first response time Td1 exceeds the first expected rear-end collision time Tx1, it is determined that the rear-end collision cannot be avoided, and when the first response time Td1 is equal to or shorter than the first expected rear-end collision time Tx1, it is determined that the rear-end collision can be avoided. .

The ROM 4 stores a second response time Td2 that does not take into account the driver's operation response time with respect to the first response time Td1. For the second response time Td2, the CPU 2 directly calculates the optimal control amount regardless of the driver's operation, and the calculation result is sent to the brake control device 14 and the fuel injection control device 15 via the vehicle input / output ECU 13. This is the time from when the brake or engine reaches the target driving amount until the vehicle is run. Accordingly, the second response time Td2 is shorter than the first response time Td1 by an amount not including the driver's operation response time.

  As shown in FIG. 2, the front millimeter wave radar 6f as the obstacle information acquisition means is attached to the center position of the front end of the host vehicle C1, emits a millimeter wave forward from the front end of the host vehicle C1, A forward vehicle C3 is detected. Then, the CPU 2 inputs a radar signal from the front millimeter wave radar 6f via the vehicle side sensor input I / F unit 6, and based on the radar signal, the vehicle speed V3 of the front vehicle C3 and the front vehicle C1 A distance (inter-vehicle distance) D2 to C3 is calculated.

  The road surface detection sensor 6g as road surface information acquisition means is attached to the front end lower center position of the host vehicle C1, detects the state of the road surface in the traveling direction (front), and outputs it to the CPU 2 as road surface information. The CPU 2 obtains a friction coefficient (dynamic friction coefficient) μ of the traveling road based on the road surface information.

  In addition, the driving support device 1 includes a geographic data storage unit 7 in which route data RD and map data MD as road map information are stored. The route data RD is data for each region that divides the whole country into regions, and includes a header RDa, node data RDb, link data RDc, link cost RDd, and coordinate data RDe, as shown in FIG. . The header RDa has data for managing each route data RD. The node data RDb includes identification data of each node indicating T-shaped intersections, cross intersections, road end points, and the like, identification data of adjacent nodes, and the like. The link data RDc constitutes a link string, and includes link records indicating connection nodes, data indicating traffic restrictions, and the like. The link cost RDd is a data group composed of a link ID, a link length, an average travel time, and the like given to each link record. The coordinate data RDe indicates the absolute coordinates of each node.

  On the other hand, the map data MD is stored for each area obtained by dividing the map of the whole country, and is divided for each layer from a wide area map to a narrow area map. As shown in FIG. 4, each map data MD has header MDa, road data MDb, and background data MDc. The header MDa indicates the hierarchy, area, etc. of the map data MD, and is management purpose data. The road data MDb is data indicating the shape and type of the road, and includes road attribute data MDd, link shape data MDe, and connection data MDf. The road attribute data MDd has a road name, a road direction, a road width, and the number of lanes. The connection data MDf is data representing the connection state between each link and each node.

  The link shape data MDe includes coordinate data MDg and shape interpolation data MDh. The coordinate data MDg indicates the coordinates of links and nodes. The shape interpolation data MDh is data relating to the shape interpolation point set in the middle of the link and set to indicate the curve shape of the road, and is data such as the coordinates of the shape interpolation point and the direction of the link. The background data MDc is drawing data for drawing roads, urban areas, rivers, and the like.

The driving support device 1 includes an image processor 8 and an external input / output I / F unit 9. The CPU 2 is connected to a display DSP that is a touch panel via the image processor 8. The display DSP inputs data indicating the destination via the external input / output I / F unit 9 by an input operation of the operation switch SW1 provided at a position adjacent to the display DSP. When this destination data is input, the CPU 2 searches for a recommended route connecting the destination and the current vehicle position using the route data RD. The display DSP includes an impact mitigation support mode setting switch SW2 for rear-end impact mitigation support. Based on the on operation of the impact mitigation support mode setting switch SW2, the CPU 2 performs a RO
The stored rear-end collision impact mitigation support program designated as M4 is executed. Therefore, when it is desired to perform driving without receiving rear-end impact mitigation support, the impact mitigation support mode setting switch SW2 is turned off.

  Further, when the CPU 2 inputs ON from the ignition switch 6d via the vehicle side sensor input I / F unit 6, the CPU 2 controls the image processor 8 to obtain the map data MD around the own vehicle position of the own vehicle C1. Read. Then, the CPU 2 outputs a map screen P (road guidance image) based on the map data MD to the display DSP via the image processor 8. At this time, the image processor 8 superimposes and displays an index P0 indicating the position of the vehicle on a road (guide route R to the destination selected by searching) on the map screen P.

  The driving support device 1 includes a voice processor 10. The CPU 2 is connected to the audio processor 10, and the audio processor 10 is connected to the speaker SP. The voice processor 10 drives the speaker SP under the control of the CPU 2 and performs voice guidance for route guidance at any time.

  The driving support device 1 includes an image data input unit 11. The image data input unit 11 is connected to the rear camera CA1 and the front camera CA2. The CPU 2 is connected to the image data input unit 11 and always activates the rear camera CA1 and the front camera CA2 via the image data input unit 11. The rear camera CA1 and the front camera CA2 include an optical mechanism including a wide-angle lens, a mirror, and the like, and a CCD image pickup device (both not shown).

  As shown in FIG. 5, the rear camera CA1 as a weight acquisition means for the rear vehicle is attached to the center position of the rear end of the host vehicle C1 (position close to the rear millimeter wave radar 6e), and the rear end of the host vehicle C1. An imaging region Z1 having an optical axis directed backward from the rear and extending rearward of the rear end portion is imaged. When the CPU 2 controls the image data input unit 11 to acquire the image data of the rear image captured by the rear camera CA1 as the rear image data G1, the CPU 2 temporarily stores it in a VRAM (not shown) of the image processor 8.

  As shown in FIG. 5, the front camera CA2 is attached to the center position of the front end of the host vehicle C1 (a position close to the front millimeter wave radar 6f) and has an optical axis that faces forward from the front end of the host vehicle C1. The imaging region Z2 that spreads forward is imaged. When the CPU 2 controls the image data input unit 11 and acquires the image data of the front image captured by the front camera CA2 as the front image data G2, the CPU 2 temporarily stores it in a VRAM (not shown) of the image processor 8.

  The image processor 8 corrects the rear image data G1 temporarily stored in the VRAM, and recognizes an image of another vehicle (rear vehicle C2) approaching from behind based on the corrected rear image data G1. First, in the present embodiment, whether or not there is the rear vehicle C2 is determined by detecting the horizontal edge and the vertical edge of the image in the rear image based on the rear image data G1, and detecting the horizontal edge and the vertical edge. Based on this, it is determined whether the image is a vehicle.

  When it is determined that the rear vehicle C2 is reflected, the image processor 8 determines the vehicle type of the rear vehicle C2. In this embodiment, the vehicle type means an ordinary cargo vehicle, an ordinary passenger car, an ordinary passenger car, a small passenger car, a small truck, a small passenger car, and the like. In this embodiment, the vehicle type of the rear vehicle C2 is determined by cutting out the license plate image from the image data of the rear vehicle C2 that has been image-recognized by the image processor 8 using the rear image data G1. Then, the classification number is recognized by image recognition and determined.

The CPU 2 calculates the vehicle type from the classification number recognized by the image processor 8, calculates the vehicle weight M2 of the vehicle type, that is, calculates the vehicle weight M2 of the rear vehicle C2 approaching from the rear. In the present embodiment and the like, the vehicle weight M2 as the weight of the rear vehicle is stored in the RAM 3 in advance for each vehicle type. When the CPU 2 determines the vehicle type, the vehicle weight M2 for the vehicle type is read from the RAM 3. ing. For each vehicle type, the vehicle weight M2 stored in the RAM 3 is the registered body weight of the vehicle belonging to that vehicle type for each vehicle type, the maximum loaded weight for a freight vehicle, and the total weight of the maximum passenger for a passenger vehicle (adult The average weight) is added and stored.

Further, the RAM 3 stores in advance, for each vehicle model, a restitution coefficient e when the rear vehicle C2 is subjected to a rear-end collision with a predetermined impact force (impact force with which the bumper is recessed).
Furthermore, in this embodiment, the vehicle weight M1 of the host vehicle C1 as the weight of the host vehicle is stored in advance in the RAM 3 by the same calculation method.

  The image processor 8 corrects the forward image data G2 temporarily stored in the VRAM, and recognizes an image of the forward vehicle C3 as an obstacle ahead based on the corrected forward image data G2. First, in the present embodiment, the determination as to whether or not the forward vehicle C3 is ahead is performed by detecting the horizontal and vertical edges of the image in the forward image based on the forward image data G2, and detecting the horizontal and vertical edges. Based on this, it is determined whether the image is a vehicle (front vehicle C3).

  When it is determined that the forward vehicle C3 is reflected, the image processor 8 determines the license plate number from the forward image data G2 of the forward vehicle C3 recognized by the backward image data G1, as described above. The image is cut out and determined as a vehicle type. The CPU 2 obtains the vehicle weight M3 for the vehicle type of the forward vehicle C3 in the same manner as described above, and stores the obtained vehicle weight M3 in the RAM 3 together with the distance (inter-vehicle distance D2) calculated by the forward millimeter wave radar 6f.

  The driving support device 1 includes a vehicle input / output I / F 12. The vehicle input / output I / F 12 is connected to a vehicle electronic control device (vehicle input / output ECU) 13. The vehicle input / output ECU 13 as the travel control means is a control device that controls a drive system related to travel of the host vehicle C1, and adjusts the amount of operation of the brake pedal to apply a predetermined brake to the host vehicle C1 ( Brake control device 14 constituting the own vehicle driving means for controlling the driving of the vehicle (not shown), the own vehicle driving for adjusting the injection amount of the engine and controlling the fuel injection device (not shown) for controlling the acceleration of the own vehicle C1. It is connected to a fuel injection control device 15 constituting the means.

  Then, when the vehicle input / output ECU 13 inputs a brake signal as travel change information for mitigating rear-end impact that is calculated and output by the CPU 2 via the vehicle input / output I / F 12, the brake input device outputs the brake signal to the brake control device. 14 for output. The brake control device 14 drives and controls the brake device based on the brake signal and applies a braking force to the host vehicle C1. Accordingly, the host vehicle C1 is braked by the braking force.

  Further, when the vehicle input / output ECU 13 inputs acceleration as travel change information for avoiding rear-end collision or mitigating rear-end impact, which is calculated and output by the CPU 2, the input / output ECU 13 outputs the acceleration to the fuel injection control device 15. The fuel injection control device 15 calculates a fuel injection amount with respect to the input acceleration, drives and controls the fuel injection device, and supplies the fuel injection amount to the engine of the host vehicle C1. Accordingly, the host vehicle C1 accelerates and decelerates based on the fuel injection amount supplied to the engine.

Next, the rear-end impact mitigation support processing of the driving support device 1 of the present embodiment will be described according to the flowchart showing the processing procedure of the driving support device 1 shown in FIG.
Now, after turning on the ignition switch 6d, the CPU 2 enters the “rear impact impact mitigation support mode” based on the selection operation of the impact mitigation support mode setting switch SW2 by the driver, and the rear impact impact mitigation support program shown in the flowchart of FIG. Execute.

  First, CPU2 calculates | requires the vehicle speed V1 of the own vehicle C1 based on the signal from the vehicle speed sensor 6a (step S1). In the present embodiment, it is assumed that a route guidance program that searches for a plurality of guide routes to the destination and guides and displays one selected guide route R among them is executed together with the rear-end collision impact mitigation support program. . Accordingly, the CPU 2 displays the road map screen P on the display DSP and also displays the guide route R to the destination.

  Subsequently, the CPU 2 checks whether or not the host vehicle C1 is traveling based on the calculated vehicle speed V1, that is, whether or not the vehicle speed V1 is “0” (step S2). When the host vehicle C1 is not traveling (NO in step S2), the CPU 2 once ends the rear-end impact mitigation support program and returns to step S1 again.

  On the other hand, when the host vehicle C1 is traveling (YES in step S2), the CPU 2 is based on the radar signal from the rear millimeter wave radar 6e and the vehicle speed V2 of the approaching rear vehicle C2 and the rear of the host vehicle C1. An inter-vehicle distance D1 to the vehicle C2 is obtained (step S3). Subsequently, based on the radar signal from the front millimeter wave radar 6f, the vehicle speed V3 of the front vehicle C3 and the inter-vehicle distance D2 from the host vehicle C1 to the front vehicle C3 are obtained (step S4). Further, the CPU 2 obtains a friction coefficient μ of the traveling road based on the road surface information from the road surface detection sensor 6g (step S5).

  Subsequently, the CPU 2 performs image recognition of the approaching rear vehicle C2 based on the rear image data G1 captured by the rear camera CA1 via the image data input unit 11, and moves backward from the license plate of the rear vehicle C2. The vehicle type of the vehicle C2 is determined. And CPU2 calculates | requires the vehicle weight M2 with respect to the calculated vehicle type (step S6).

  Subsequently, the CPU 2 determines whether or not the rear collision of the rear vehicle C2 cannot be avoided based on the vehicle speeds V1 and V2 and the inter-vehicle distance D1 obtained in steps S1 and S3 (step S7). More specifically, the CPU 2 first obtains the relative speed Vs1 (= V2−V1) of the host vehicle C1 and the rear vehicle C2, and calculates the first estimated collision time from the relative speed Vs1 (= V2−V1) and the inter-vehicle distance D1. Tx1 (= D1 / Vs1) is calculated. Then, the CPU 2 reads the first response time Td1 stored in the ROM 4 and determines whether or not a collision can be avoided.

  When it is determined that the rear collision of the rear vehicle C2 can be avoided when the first response time Td1 is equal to or shorter than the first predicted rear collision time Tx1 (NO in step S7), the CPU 2 returns to step S1 and again executes the rear collision impact mitigation support program. Run from the beginning.

  On the other hand, if the first response time Td1 exceeds the first expected rear-end collision time Tx1 and it is determined that the rear-end collision of the rear vehicle C2 cannot be avoided by the driver's operation (YES in step S7), the CPU 2 proceeds to step S8. . In step S8, the CPU 2 calculates how much the host vehicle C1 should be accelerated in order to avoid a rear-end collision of the rear vehicle C2, and accelerated the host vehicle C1 with the acceleration based on the calculation. The possibility of a rear-end collision with the forward vehicle C3 traveling ahead is calculated.

  More specifically, the CPU 2 determines the acceleration for at least the relative speed Vs1 to be “0”, that is, the vehicle speed V1 of the host vehicle C1 is the same as the vehicle speed V2 of the rear vehicle C2 before the first expected rear-end time Tx1. calculate. When the host vehicle C1 is accelerated by the acceleration, the CPU 2 calculates the possibility of a rear-end collision with the front vehicle C3 in which the host vehicle C1 is traveling at the inter-vehicle distance D2 and the vehicle speed V3.

First, the CPU 2 determines the relative speed Vs2 and the inter-vehicle distance D2 between the host vehicle C1 and the preceding vehicle C3.
The second expected collision time Tx2 (= D2 / Vs2) until the collision is calculated. The CPU 2 compares the second response time Td2 with the second expected rear-end collision time Tx2, and determines whether or not the rear-end collision with the preceding vehicle C3 can be avoided (Td2 <Tx2). The reason why the acceleration control is compared with the second response time Td2 is that the acceleration control is calculated by the CPU 2 and directly controlled via the vehicle input / output ECU 13 regardless of the operation of the driver.

  If the CPU 2 determines that the second response time Td2 is less than the second expected rear collision time Tx2 and does not collide with the preceding vehicle C3 (YES in step S9), the CPU 2 outputs the calculated acceleration that can be avoided to the vehicle input / output ECU 13 to avoid the rear collision. Acceleration control is executed for (step S10). That is, the vehicle input / output ECU 13 outputs the first acceleration to the fuel injection control device 15, and the fuel injection control device 15 calculates the fuel injection amount with respect to the input first acceleration to drive and control the fuel injection device. The fuel injection amount is supplied to the engine of the host vehicle C1. As a result, the host vehicle C1 is accelerated and avoided from the rear collision of the rear vehicle C2 without colliding with the front vehicle C3.

  On the other hand, when it is determined that the second response time Td2 is equal to or longer than the second expected rear collision time Tx2 and the vehicle collides with the front vehicle C3 by the acceleration control (NO in step S9), the CPU 2 determines in advance when the rear vehicle C2 collides. In order to be impacted by the impact force of the reference impact force (in this embodiment, the impact force with which the bumper is recessed), a new acceleration is calculated as to how much the host vehicle C1 should be accelerated, When the host vehicle C1 is accelerated with a new acceleration based on the calculation, the possibility of a rear-end collision with the front vehicle C3 traveling ahead is calculated (step S11).

  More specifically, first, the CPU 2 receives an impact force of a predetermined reference impact force from the vehicle weight M2 of the rear vehicle C2 obtained in step S6 and the vehicle weight M1 of the host vehicle C1, that is, for each vehicle type. The possibility that the vehicle collides with the rebound coefficient e stored in the RAM 3 prepared in advance and collides with the preceding vehicle C3 is calculated.

Here, the vehicle speed V1 before the collision of the host vehicle C1 is V10, and the vehicle speed V1 after the collision is V11. The vehicle speed V2 before the collision of the rear vehicle C2 is V20, and the vehicle speed V2 after the collision is V21.
From the law of conservation of momentum, the following equation holds.

M1 · V10 + M2 · V20 = M1 · V11 + M2 · V21
Further, when the restitution coefficient at the time of collision is e, the following equation is established.
e =-(V21-V11) / (V20-V10)
From these two formulas, the vehicle speed V11 immediately after the collision of the host vehicle C1 is as follows.

V11 = (1 + e) · (V20−V10) · M2 / (M1 + M2) + V10 (1)
Incidentally, the vehicle speed V21 immediately after the collision of the rear vehicle C2 is as follows.

V21 =-(1 + e). (V20-V10) .M1 / (M1 + M2) + V20
Here, the restitution coefficient e is the restitution coefficient e stored in the RAM 3 and obtained by experiment or test for each vehicle type. Since the vehicle type is known by image recognition, the restitution coefficient e for each vehicle type can be easily obtained. Can be read.

  Then, with respect to equation (1), the vehicle speed V20 before the collision of the rear vehicle C2 is set to the vehicle speed V2 obtained in step S3, the vehicle speed V10 before the collision is appropriately selected, and the vehicle speed V11 after the collision is obtained.

That is, when the CPU 2 sets one vehicle speed V10 before the collision, the set vehicle speed V10 is set.
On the other hand, the vehicle speed V11 after the collision is obtained. The CPU 2 calculates the second expected rear collision time Tx2 (= D2 / Vs2) to reach the forward vehicle C3 traveling at the vehicle speed V3 at the calculated vehicle speed V11.

  More specifically, a relative speed Vs2 (= V11−V3) between the host vehicle C1 and the preceding vehicle C3 is obtained, and a second predicted collision time Tx2 until the collision is calculated from the relative speed Vs2 and the inter-vehicle distance D2. At this time, the vehicle speed V1 (the initial speed is V11) of the host vehicle C1 traveling to the forward vehicle C3 is determined in consideration of the road surface friction coefficient μ obtained in step S5, and the second predicted rear-end collision time Tx2 is determined from the relative speed Vs2. Calculated. Accordingly, it is possible to obtain a more accurate second collision expectation time Tx2.

  Then, the CPU 2 compares the second response time Td2 with the second expected rear collision time Tx2, and determines whether the rear collision can be avoided. After determining whether or not there is a rear-end collision, the CPU 2 calculates an acceleration for setting the vehicle speed V10 before the collision from the current vehicle speed V1 obtained in step 1.

  When the presence / absence and acceleration of the rear-end collision are obtained for one vehicle speed V10 before the collision, the next new vehicle speed V10 before the collision is set, and similarly, the presence / absence of the rear-end collision and the acceleration are obtained. Thereafter, a predetermined number of vehicle speeds V10 are set, and similarly, the presence or absence of rear-end collision and the acceleration are obtained.

  Here, the range of the vehicle speed V10 before the collision to be set is a range (acceleration can be performed) from the current vehicle speed V1 obtained in step 1 within the first predicted collision time Tx1 from the performance of the host vehicle C1. The range is obtained in advance by a test or the like, and is selected and set as appropriate within the obtained range.

  When the presence / absence of a rear-end collision with respect to the plurality of vehicle speeds V10 before the collision and the acceleration are obtained, the CPU 2 determines whether or not the rear-end vehicle C3 collides with the front vehicle C3 (step S12). At this time, the CPU 2 determines whether or not there is a pre-collision vehicle speed V10 that does not collide with the preceding vehicle C3 among the plurality of pre-collision vehicle speeds V10.

  If there is a vehicle speed V10 before the collision that does not make a collision with the forward vehicle C3 (YES in step S12), the CPU 2 moves to step S13 and executes acceleration control for shock mitigation. That is, the CPU 2 outputs the acceleration with respect to the vehicle speed V10 before the collision without collision to the vehicle input / output ECU 13, and executes acceleration control for shock mitigation. The vehicle input / output ECU 13 outputs the acceleration to the fuel injection control device 15, the fuel injection control device 15 calculates the fuel injection amount for the input acceleration, and controls the drive of the fuel injection device to the engine of the host vehicle C1. The fuel injection amount is supplied. As a result, the host vehicle C1 does not collide with the front vehicle C3, and the rear vehicle C2 receives an impact force equal to or less than the reference impact force (in this embodiment, the impact force with which the bumper is recessed) from the rear vehicle C2. Rear end.

  When there are a plurality of vehicle speeds V10 before the collision that does not collide with the preceding vehicle C3, in this embodiment, the vehicle speed V10 before the collision when the vehicle speed V11 immediately after the collision of the host vehicle C1 is the smallest is selected. Acceleration control is performed with the acceleration corresponding to the selected vehicle speed V10.

On the other hand, when there is no vehicle speed V10 before the collision that does not collide with the preceding vehicle C3, that is, when it is determined that the vehicle collides with the preceding vehicle C3 (NO in step S12), the CPU 2 does not perform the acceleration control of the own vehicle C1, and Drive control is performed and braking is applied to the host vehicle C1. More specifically, the CPU 2 outputs a brake signal to the vehicle input / output ECU 13 and executes brake control for reducing the impact between the preceding vehicle C3 and the host vehicle C1 (step S13). The vehicle input / output ECU 13 outputs the brake signal to the brake control device 14, and the brake control device 14 drives and controls the brake device with the input brake signal to apply a braking force to the host vehicle C1. Accordingly, the host vehicle C1 makes a collision with the front vehicle C3 with a small impact force while braking.

According to this embodiment, the following effects can be obtained.
(1) In this embodiment, when it is determined that rear-end collision with the rear vehicle C2 cannot be avoided even if acceleration control is performed, the vehicle speed V1 of the rear vehicle C2 and the vehicle speed V1 of the host vehicle C1 are determined. In addition, taking into account the vehicle weight M1 of the host vehicle C1 and the vehicle weight M2 of the rear vehicle C2, the acceleration when the vehicle collides with the minimum impact force and does not collide with the front vehicle C3 was calculated. In other words, the acceleration for colliding with the rear vehicle C2 is calculated by receiving the impact force of the minimum reference impact force such that the impact from the rear vehicle C2 dents the bumper, and the own vehicle C1 is accelerated with the calculated acceleration. I tried to do it.

Therefore, the host vehicle C1 can absorb the rear-end collision with the minimum reference impact force without depending on the vehicle type of the rear vehicle C2.
(2) In this embodiment, even if the rear impact can be absorbed with the impact force of the minimum reference impact force, if the own vehicle C1 collides with the front vehicle C3 due to the rear impact with the rear vehicle, The vehicle C1 is braked. Therefore, the impact caused by the rear-end collision with the forward vehicle C3 is reduced.

  (3) In this embodiment, the road friction sensor μ is detected by the road surface detection sensor 6g, and the vehicle speed V11 of the host vehicle C1 immediately after the rear-end collision with the rear vehicle C2 is obtained by taking the friction coefficient μ into consideration. Therefore, it is possible to more accurately determine whether or not to avoid a collision with the preceding vehicle C3, and it is possible to control the avoidance of the own vehicle C1 with respect to the preceding vehicle C3 or the impact mitigation with high accuracy.

  (4) In this embodiment, the vehicle type of the rear vehicle C2 is determined by recognizing the license plate image. Therefore, the vehicle type of the rear vehicle C2 can be recognized easily and reliably and the vehicle weight M2 can be obtained. In addition, in the present embodiment, the vehicle weight M2 is a value obtained by adding the maximum load weight to the weight of the vehicle if it is a freight vehicle and the weight of the maximum passenger (the average weight of an adult) for a passenger car. It becomes possible to control.

  (5) In the present embodiment, when there are a plurality of vehicle speeds V10 before the collision that does not collide with the preceding vehicle C3, the vehicle speed V10 before the collision when the vehicle speed V11 immediately after the collision of the host vehicle C1 is the lowest is selected. The acceleration control was performed with the acceleration corresponding to the selected vehicle speed V10. Therefore, the impact force received can be minimized.

In addition, you may change each said embodiment as follows.
In the above embodiment, the restitution coefficient e of each vehicle type is a value for receiving the impact force of the minimum reference impact force that the bumper is recessed, but is not limited to this, and can be changed as appropriate. You may implement.

  In the above embodiment, the vehicle type of the rear vehicle C2 is determined by recognizing the license plate image, but it may not be the license plate. For example, the shape of the rear vehicle C2 is image-recognized, and the rear vehicle C2 is determined from the shape. The vehicle type may be recognized.

In the above embodiment, the presence or absence of a rear-end collision with the forward vehicle C3 is determined in consideration of the friction coefficient μ of the road surface, but this may be omitted.
In the above embodiment, the vehicle driving means is the brake control device 14, but is not limited to this, for example, a shift control device that controls a shift of an automatic transmission or a drive like an electric vehicle The present invention may also be applied to a control device that drives and controls a motor.

  In the above embodiment, the front camera CA2 is not used for shock reduction, but instead of the front millimeter wave radar 6f that detects the front vehicle C3, the front image data G2 of the front camera CA2 is used for shock reduction. May be used for

In the above embodiment, the obstacle is the front vehicle C3. However, the obstacle is not limited to the vehicle, and may be a fence, a sign, an installation for road construction, or the like.
In the above embodiment, the maximum weight of the occupant and the loaded luggage is considered for the vehicle weight M2 of the rear vehicle C2. However, the maximum weight of the occupant and the loaded luggage may be omitted, and the vehicle weight M2 may be performed only by the vehicle weight.

The block diagram explaining the structure of the driving assistance device of this embodiment. Explanatory drawing for demonstrating a millimeter wave radar. Explanatory drawing for demonstrating the data structure of path | route data. Explanatory drawing for demonstrating the data structure of map data. Explanatory drawing for demonstrating a back and front camera and its imaging range. The flowchart for demonstrating rear-end collision impact relaxation assistance operation | movement.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Driving assistance device, 2 ... CPU, 3 ... RAM, 4 ... ROM, 5 ... GPS receiving part, 6 ... Vehicle side sensor input I / F part, 6a ... Vehicle speed sensor, 6b ... Gyro, 6c ... Steering sensor, 6d ... Ignition switch, 6e ... Rear millimeter wave radar, 6f ... Front millimeter wave radar, 6g ... Road surface detection sensor, 7 ... Geographic data storage unit, 8 ... Image processor, 13 ... Vehicle electronic control device (vehicle input / output ECU) , 14 ... brake control device, 15 ... fuel injection control device, DSP ... display, SW2 ... impact mitigation support mode setting switch, C1 ... own vehicle, C2 ... rear vehicle, C3 ... front vehicle, CA1 ... rear camera, CA2 ... front Camera, M1 ... car weight, M2 ... car weight, M3 ... car weight.

Claims (6)

A vehicle driving support method for acquiring approach information of a rear vehicle and host vehicle traveling information of the host vehicle, judging whether or not the rear vehicle has a collision, and avoiding or relieving the impact of the rear collision. ,
Obtain the weight of the host vehicle and the weight of the rear vehicle,
When it is determined that a rear-end collision cannot be avoided based on the approach information and the host vehicle travel information,
Based on the weight information of the host vehicle and the weight of the rear vehicle in addition to the approach information and the host vehicle travel information, travel change information for changing the travel state of the host vehicle for shock mitigation is obtained and obtained. A driving support method for a vehicle, wherein the vehicle is controlled to travel based on the travel change information. The vehicle driving support method according to claim 1,
In addition, the obstacle information ahead of the host vehicle is acquired,
In addition to the approach information, the own vehicle travel information, the weight of the own vehicle, and the weight of the rear vehicle, the travel change information is obtained based on the obstacle information, and the own vehicle is obtained based on the obtained travel change information. A driving support method for a vehicle, characterized in that the vehicle is travel-controlled. The vehicle driving support method according to claim 2,
Furthermore, the road surface information ahead of the host vehicle is acquired,
The travel change information is obtained based on the road information in addition to the approach information, the own vehicle travel information, the weight of the own vehicle, the weight of the rear vehicle, and the obstacle information, and based on the obtained travel change state. And a vehicle driving support method, wherein the vehicle driving control is performed. Approach information acquisition means for acquiring approach information of the rear vehicle;
Own vehicle traveling information acquisition means for acquiring own vehicle traveling information of the own vehicle;
Based on the approach information and the host vehicle travel information, a determination unit that determines whether there is a rear collision of the rear vehicle;
A change information calculation means for obtaining travel change information of the own vehicle for avoiding the rear collision or for mitigating the impact caused by the rear collision when the determination means determines that the rear collision cannot be avoided;
A driving support device for a vehicle comprising driving control means for driving and controlling the own vehicle driving means based on the driving change information,
Storage means for storing the weight of the host vehicle;
A rear vehicle weight acquisition means for acquiring the weight of the rear vehicle,
When the determination means determines that rear-end collision cannot be avoided, the change information calculation means is configured to change the travel based on the weight of the host vehicle and the weight of the rear vehicle in addition to the approach information and the host vehicle travel information. A driving support apparatus for a vehicle, characterized in that information is obtained. The vehicle driving support device according to claim 4,
Comprising obstacle information acquisition means for acquiring obstacle information ahead of the host vehicle;
The change information calculation means obtains the travel change information based on the obstacle information in addition to the approach information, the host vehicle travel information, the weight of the host vehicle, and the weight of the rear vehicle. Vehicle driving support device. The vehicle driving support device according to claim 5,
Comprising road surface information acquisition means for acquiring road surface information ahead of the host vehicle,
The change information calculation means obtains the travel change information based on the road surface information in addition to the approach information, the host vehicle travel information, the weight of the host vehicle, the weight of the rear vehicle, and obstacle information. A vehicle driving support device.

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