JP7060976B2 - Vehicle control device and vehicle control method - Google Patents

Description

The present invention relates to a vehicle control device and a vehicle control method.

Conventionally, for example, Patent Document 1 below describes that a rear window is used as a screen to notify the driver of a following vehicle of the state of the own vehicle. Further, Patent Document 2 below includes a configuration including a display device in which the viewing length of the alerting portion visually recognized by the driver of the following vehicle expands and contracts in a band shape according to the distance between the own vehicle and the following vehicle. Have been described.

Japanese Unexamined Patent Publication No. 2000-168352 Japanese Unexamined Patent Publication No. 2014-102770

Recently, a technique of recognizing a person's condition based on facial image information has become common. For example, the following Non-Patent Document 1 describes a technique for monitoring the state of a driver during driving by face recognition.

However, the appropriate inter-vehicle distance varies depending on the road surface condition on which the vehicle travels. For example, when the road surface friction coefficient is low, the vehicle is more likely to slip than when the road surface friction coefficient is high, so it is desirable to keep the inter-vehicle distance wider.

In the methods described in Patent Documents 1 and 2, since the road surface condition on which the vehicle travels is not taken into consideration, it is not possible to display the inter-vehicle distance according to the road surface condition. In particular, in the methods described in Patent Documents 1 and 2, in a situation where the road surface friction coefficient changes, such as when there is a road surface having a lower friction coefficient in front of the vehicle with respect to the road surface on which the vehicle is traveling. It is difficult to optimally display the distance between vehicles.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is that it is possible to optimally display the inter-vehicle distance according to the road surface condition on which the vehicle is traveling. It is an object of the present invention to provide a new and improved vehicle control device and a vehicle control method.

In order to solve the above problems, according to a certain viewpoint of the present invention, a first road surface friction coefficient calculation unit that calculates a first road surface friction coefficient based on a value detected from a hub unit sensor provided on the axle. , The second road surface friction coefficient calculation unit that calculates the second road surface friction coefficient based on the detection value from the non-contact sensor that detects the road surface condition in front of the vehicle in a non-contact manner, the first road surface friction coefficient and the above. A display control unit that controls a display regarding the inter-vehicle distance based on the second road surface friction coefficient is provided , and the display control unit has a first road surface friction coefficient larger than the second road surface friction coefficient. Provided is a vehicle control device that controls a display regarding the inter-vehicle distance when the difference between the first road surface friction coefficient and the second road surface friction coefficient is larger than a predetermined value .

Further, the display control unit includes an environment information acquisition unit that acquires a distance from the vehicle behind, and the display control unit has a first road surface friction coefficient larger than the second road surface friction coefficient, and has the same as the first road surface friction coefficient. When the difference of the second road surface friction coefficient is larger than a predetermined value and the distance to the rear vehicle is within a predetermined range, the display regarding the inter-vehicle distance may be controlled.

Further, the display control unit may change the display regarding the inter-vehicle distance according to the distance to the rear vehicle.

Further, the display control unit may control the display of an index that increases or decreases according to the distance to the vehicle behind the vehicle as a display relating to the inter-vehicle distance.

Further, even if the display control unit controls a display for warning to the driver of the rear vehicle or the own vehicle when the distance to the rear vehicle is equal to or less than the lower limit value of the predetermined range. good.

Further, the environmental information acquisition unit acquires the position of the rear vehicle in addition to the distance of the rear vehicle, and the display control unit obtains the inter-vehicle distance according to the position of the rear vehicle and the position of the driver of the own vehicle. It may control the position on the window portion behind the vehicle, which displays a display related to the distance.

Further, the display control unit may not display the inter-vehicle distance when the vehicle speed is equal to or less than a predetermined value.

Further, the display control unit may control the display regarding the inter-vehicle distance displayed on the display device that displays on the window unit behind the vehicle.

Further, in order to solve the above problems, according to another viewpoint of the present invention, a step of calculating a first road surface friction coefficient based on a value detected from a hub unit sensor provided on the axle and a step in front of the vehicle. The step of calculating the second road surface friction coefficient based on the detection value from the non-contact sensor that detects the road surface condition in a non-contact manner, and the inter-vehicle distance based on the first road surface friction coefficient and the second road surface friction coefficient. In the step of controlling the display relating to the distance and the step of controlling the display relating to the inter-vehicle distance, the first road surface friction coefficient is larger than the second road surface friction coefficient, and the first road surface friction coefficient is combined with the first road surface friction coefficient. Provided is a vehicle control method for controlling the display regarding the inter-vehicle distance when the difference of the second road surface friction coefficient is larger than a predetermined value .

According to the present invention, it is possible to optimally display the inter-vehicle distance according to the road surface condition on which the vehicle is traveling.

It is a schematic diagram which shows the structure of the vehicle system which concerns on one Embodiment of this invention. It is a schematic diagram which shows the HUD apparatus using a self-luminous interlayer film. It is a schematic diagram which shows the state which a driver sensor is taking a picture of a driver. It is a schematic diagram which shows the state of calculating the angle and the like which a face faces based on the face area of a driver. It is a schematic diagram which shows the map used when the 2nd friction coefficient calculation part determines the road surface condition. It is a schematic diagram which shows by decomposing the map 3D map of FIG. 5A into a 2D map. It is a schematic diagram which shows by decomposing the map 3D map of FIG. 5A into a 2D map. It is a schematic diagram which shows by decomposing the map 3D map of FIG. 5A into a 2D map. It is a schematic diagram which shows by decomposing the map 3D map of FIG. 5A into a 2D map. It is a schematic diagram which shows the example of the database which prescribed the relationship between the road surface condition and the friction coefficient. It is a characteristic diagram which shows the relationship between _LC and _VF . It is a characteristic diagram which shows the relationship between L _min and _VF . It is a flowchart which shows the process performed in the vehicle system which concerns on this embodiment. It is a schematic diagram which shows the example of the display on the rear glass of a vehicle by a HUD device. It is a schematic diagram which shows the example of the display on the rear glass of a vehicle by a HUD device. It is a schematic diagram which shows the example of the display on the rear glass of a vehicle by a HUD device. It is a schematic diagram which shows the principle of displaying a display in an appropriate position when displaying on a rear glass.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

FIG. 1 is a schematic diagram showing a configuration of a vehicle system 1000 according to an embodiment of the present invention. The vehicle system 1000 is basically a system configured in a vehicle such as an automobile. As shown in FIG. 1, the vehicle system 1000 includes an external sensor 100, a vehicle speed sensor 110, a driver sensor 120, a room mirror sensor 130, a first road surface friction coefficient sensor 150, a second road surface friction coefficient sensor 160, and a control device 200. , HUD device 500, and navigation device 600.

The vehicle exterior sensor 100 is composed of a stereo camera, a monocular camera, a millimeter wave radar, an infrared sensor, and the like, and measures the position and speed of a person or vehicle around the own vehicle. When the vehicle exterior sensor 100 is composed of a stereo camera, the stereo camera is configured to have a pair of left and right cameras having image pickup elements such as a CCD sensor and a CMOS sensor, and images and images the external environment outside the vehicle. Image information is sent to the control device 200. As an example, a stereo camera is composed of a color camera capable of acquiring color information and is installed on the upper part of the windshield of a vehicle. The vehicle speed sensor 110 is a sensor that detects the vehicle speed V.

The driver sensor 120 is composed of a camera, a line-of-sight sensor, a motion sensor, and the like, and measures the movement of the head and arms of the driver (driver), the line-of-sight direction, and the like. When the driver sensor 120 is composed of a camera, the movement of the head and arms, the direction of the line of sight, and the like are acquired by performing image processing on the image captured by the camera. When the driver sensor 120 is composed of a line-of-sight sensor, the line-of-sight detection is performed by a method such as a corneal reflex method.

The rear-view mirror sensor 130 is a sensor that detects the angle and direction of the rear-view mirror provided in the vehicle. As will be described later, the HUD device 500 displays the rear-view mirror at a desired position based on the angle of the rear-view mirror, the position of the driver's eyes, and the position of the following vehicle.

The first road surface friction coefficient sensor 150 and the second road surface friction coefficient sensor 160 detect various parameters for acquiring the road surface friction coefficient. The first road surface friction coefficient sensor 150 is composed of a hub unit sensor provided on the hub of the wheel, and detects the acting force acting on the front and rear wheels of the vehicle. The acting force detected by the first road surface friction coefficient sensor 150 includes a component force in three directions including a longitudinal force Fx, a lateral force Fy, and a longitudinal force Fz, and a torque Ty around the axis of the hub (axle). be. The front-rear direction force Fx is a component force generated in the direction parallel to the wheel center surface (x-axis direction, front-rear direction) among the frictional forces generated on the ground contact surfaces of the front and rear wheels, and the lateral force Fy is the wheel center. It is a component force generated in the direction perpendicular to the surface (y-axis direction, lateral direction). The wheel center surface is a surface orthogonal to the axle and passing through the center of the wheel width. On the other hand, the vertical force Fz is a force acting in the vertical direction (z-axis), that is, a so-called vertical load. Torque Ty is the torque (torsional force) around the axle of the tire.

For example, the front wheels and the rear wheels are mainly composed of a strain gauge and a signal processing circuit that processes an electric signal output from the strain gauge and generates a detection signal according to the acting force. Based on the knowledge that the stress generated in the hub is proportional to the acting force, the acting force is directly detected by embedding the strain gauge in the hub. As for the specific configuration of the detection unit 420, for example, the configurations disclosed in Japanese Patent Application Laid-Open No. 04-331336, Japanese Patent Application Laid-Open No. 10-318862, Japanese Patent No. 4277799 and the like can be adopted. The first road surface friction coefficient sensor 150 may be provided on a drive shaft that transmits a driving force to the front wheels or the rear wheels.

The HUD (Head-up Display) device 500 is a display device that directly displays information in the human field of view, and displays a real image on glass such as a windshield or a rear glass of an automobile. A device for displaying a virtual image is generally known as a HUD, but in the present embodiment, a display device for displaying a real image is used. Since the HUD device 500 displays a real image, the viewing angle is approximately 360 °, and the display can be visually recognized from inside and outside the vehicle.

More specifically, as the HUD device 500, a device using a self-luminous interlayer film 510 as shown in FIG. 2 can be used. In this case, on the windshield, rear glass, etc. of the vehicle, the self-luminous interlayer film 510 is arranged so as to be sandwiched between the two glass 520s on the front and back sides. The self-luminous interlayer film 510 contains a light-emitting material, and when laser light is irradiated from the projector 530 installed in the vehicle, the irradiated portion emits light and characters and images are displayed. The displayed object has visibility from all angles, and can be visually recognized from seats other than the driver's seat and from outside the vehicle. The HUD device 500 can also be configured by arranging a self-luminous type device on the glass of the vehicle. In this case, for example, a transparent screen using an organic EL element, a transmissive liquid crystal display, or the like can also be used. Further, as the display device, a device other than the HUD device 500 may be used, and for example, a large liquid crystal device or an LED display device installed on the instrument panel may be used. In the following, the HUD device 500 that displays on the window portion (glass) of the vehicle as a display device will be described as an example, but the display device according to the present invention is not limited to this, and is not limited to the inside of the vehicle. Alternatively, it includes all aspects of the display device provided externally. For example, the display device according to the present embodiment may be provided in a portion other than the window portion (body, etc.) outside the vehicle, or may be provided in a portion other than the window portion (instrument panel, seat, etc.) inside the vehicle. Further, the display device provided inside the vehicle and the display device provided outside the vehicle may be integrated or separate.

The navigation device 600 searches for a route from the current location to the destination based on the map information. Therefore, the navigation device 600 can acquire the current position of the vehicle by a global positioning system (GPS) or the like. Further, the navigation device 600 remembers the route on which the vehicle has traveled to the current location.

The control device 200 controls the display by the HUD device 500 based on the information detected by the vehicle exterior sensor 100, the driver sensor 120, the first road surface coefficient sensor 150, the second road surface friction coefficient sensor 160, and the like. Therefore, the control device 200 includes an environmental information acquisition unit 202, a driver information acquisition unit 204, a first friction coefficient calculation unit 210, a second friction coefficient calculation unit 220, an inter-vehicle distance determination unit 230, and a display control unit 240. are doing. Each component of the control device 200 can be configured by a circuit (hardware), a central processing unit such as a CPU, and a program (software) for functioning the central processing unit.

The environmental information acquisition unit 202 transfers the stereo image pair of the left and right images captured by the left and right stereo camera pairs of the stereo cameras constituting the vehicle exterior sensor 100 from the amount of deviation of the corresponding positions to the object by the principle of triangulation. Distance information can be generated and acquired. As a result, the environmental information acquisition unit can acquire the inter-vehicle distance _LM between the own vehicle and the following vehicle. At the same time, the environment information acquisition unit 202 can acquire the position information of the subject from the image information. Further, the environment information acquisition unit 202 performs a well-known grouping process on the distance information generated by the principle of triangulation, and the grouped distance information is set in advance as three-dimensional object data or the like. By comparing, three-dimensional object data, white line data, etc. are detected. As a result, the control device 200 can also recognize a person, another vehicle, a stop sign, a stop line, an ETC gate, and the like.

Further, the environmental information acquisition unit 202 can calculate the amount of change in the distance between the person and the other vehicle and the relative speed by using the distance information between the person and the other vehicle generated by the principle of triangulation. The amount of change in distance can be obtained by integrating the distances between the frame images detected every unit time. Further, the relative speed can be obtained by dividing the distance detected for each unit time by the unit time.

In this way, the environmental information acquisition unit 202 acquires the image information outside the vehicle obtained from the outside sensor 100, performs image analysis processing, analyzes the image information, and acquires the environment information outside the vehicle.

FIG. 3 is a schematic diagram showing a state in which the driver sensor 120 is photographing the driver when the driver sensor 120 is composed of a camera. As shown in FIG. 3, the driver sensor 120 is installed on the upper part of the steering column as an example.

When the driver sensor 120 is composed of a camera, the image taken by the driver sensor 120 is input to the control device 200. The driver information acquisition unit 204 acquires the face area of the driver from the input image by using image processing techniques such as edge detection and face detection, and acquires the face orientation based on the face area. Further, the driver information acquisition unit 204 detects the position information of the feature points of each part of the face such as eyes, nose, and mouth.

FIG. 4 is a schematic diagram showing how the angle at which the face is facing is calculated based on the detected face region 10 of the driver. Based on the driver's face area 10 obtained from the image information, the possibility of inattentiveness can be determined by monitoring whether or not the driver's face orientation is out of the predetermined area. The face area 10 of the driver can be set from the position information of the feature points of each part of the face such as eyes, nose, and mouth. Further, the face orientation can be estimated, for example, by using the eye spacing when viewed from the front as a reference and comparing this reference with the eye spacing obtained from the image information. It can be determined that the smaller the eye spacing obtained from the image information is, the more the face orientation is laterally displaced from the front. As these methods, for example, the method described in Non-Patent Document 1 described above can be used.

When the first friction coefficient calculation unit 210 of the control device 200 detects a component force in three directions including the front-rear direction force Fx, the lateral force Fy and the vertical force Fz by the first road surface friction coefficient sensor 150, the first friction coefficient calculation unit 210 determines this. Based on this, the coefficient of friction of the road surface is calculated in real time. The road friction coefficient μ _H can be calculated from the following equation.
μ _H = √ (Fx ² + Fy ² ) / Fz

The vehicle behavior can be stabilized by calculating the road surface friction coefficient μ _H by the first friction coefficient calculation unit 210 and controlling the driving force based on the friction circle of the tire. On the other hand, the road surface friction coefficient μ _H calculated by the first friction coefficient calculation unit 210 is the friction coefficient of the road surface currently running, which is measured after the tire actually touches the road surface for which the road surface friction coefficient is to be measured. be. Therefore, when the control driving force is controlled based on the road surface friction coefficient μ _H , for example, when the vehicle enters an extremely low μ road such as a frozen road from a high μ road, the vector of the resultant force of Fx and Fy becomes. It may run off the tire friction circle on low μ roads and cause slippage before proper control of the driving force.

Therefore, in the present embodiment, apart from the estimation of the road surface friction coefficient μ _H using the first road surface friction coefficient sensor 150, the vehicle whose tires are not yet in contact with the ground using the second road surface friction coefficient sensor 160. Estimate the coefficient of friction of the road surface ahead. The second road surface friction coefficient sensor 160 is a non-contact type such as a camera that images the front of the vehicle, a temperature sensor (outside temperature sensor, road surface temperature sensor), a near infrared sensor, and a laser light sensor (TOF (Time of Flight) sensor). It is a hybrid type sensor equipped with a sensor, and detects an image, temperature, road surface condition, etc. in front of the vehicle. When determining the road surface condition by the second road surface friction coefficient sensor 160, for example, the method described in Japanese Patent Application Laid-Open No. 2006-46936 may be adopted.

The second friction coefficient calculation unit 220 of the control device 200 calculates the friction coefficient of the road surface in real time based on the detection of the image, temperature, etc. in front of the vehicle by the second road surface friction coefficient sensor 160.

Specifically, the second friction coefficient calculation unit 220 acquires the color of the road surface in front of the vehicle, the road surface roughness, and the like from the image of the camera of the second road surface friction coefficient sensor 160. Further, the second friction coefficient calculation unit 220 acquires the outside air temperature and the road surface temperature from the non-contact thermometer of the second road surface friction coefficient sensor 160.

Further, the second friction coefficient calculation unit 220 acquires the water content of the road surface from the detection value of the near infrared sensor of the second road surface friction coefficient sensor 160. When the road surface is irradiated with near-infrared rays, if the road surface has a large amount of water, the amount of near-infrared rays reflected decreases, and if the road surface has a small amount of water, the amount of near-infrared rays reflected increases. Therefore, the second friction coefficient calculation unit 220 can acquire the water content of the road surface based on the detected value of the near infrared sensor.

Further, the second friction coefficient calculation unit 220 acquires the roughness of the road surface from the laser light sensor of the second road surface friction coefficient sensor 160. More specifically, the roughness (unevenness) of the road surface in front of the vehicle can be acquired based on the time from the irradiation of the laser beam to the detection of the reflected light. The second friction coefficient calculation unit 220 acquires the roughness of the road surface in the region in front of the vehicle, taking into consideration the amount of movement of the road surface due to the traveling of the vehicle, based on the vehicle speed.

The second friction coefficient calculation unit 220 is based on these information acquired from the second road surface friction coefficient sensor 160, and the road surface conditions are dry (D), wet (W), snow (S), and ice (I). Is determined. FIG. 5A is a schematic diagram showing a map used by the second friction coefficient calculation unit 220 to determine the road surface condition. The map shown in FIG. 5A is a three-dimensional map whose parameters are normalized values of the road surface temperature, the road surface unevenness, and the water content of the road surface. 5B to 5E are schematic views showing the map 3D map of FIG. 5A decomposed into a two-dimensional map. FIG. 5B is a coordinate system of road surface temperature (Z-axis), road surface unevenness (X-axis), and road surface water content (Y-axis), and FIG. 5C is a two-dimensional map of surface (1) of FIG. 5B. 5B shows a two-dimensional map of the (2) plane of FIG. 5B, and FIG. 5E shows a two-dimensional map of the (3) plane of FIG. 5B. The second friction coefficient calculation unit 220 applies the road surface temperature, road surface unevenness, and road surface moisture content acquired from the values detected by the second road surface friction coefficient sensor 160 to the map of FIG. 5A to determine the road surface condition.

Then, the second friction coefficient calculation unit 220 calculates the road surface friction coefficient μN by reflecting the road surface state determined from the map of FIG. 5A in a database in which the relationship between the road surface state and the road surface friction coefficient is predetermined. FIG. 6 is a schematic diagram showing an example of a database in which the relationship between the road surface condition and the coefficient of friction is predetermined. As the relationship between the road surface condition and the friction coefficient shown in FIG. 6, the friction coefficient table described on the homepage of the Japan Traffic Accident Forensics Research Institute (http://weekend.nikkouken.com/week47/409/) is used. be able to. In the database shown in FIG. 6, in the vertical direction, the coefficient of friction according to the road surface conditions "asphalt", "concrete", "gravel", "ice", and "snow" is shown. Further, in the lateral direction, the coefficient of friction according to dry (dry (D)) and wet (wet (W)) is shown as the road surface condition.

The second friction coefficient calculation unit 220 applies the road surface condition determined from the map of FIG. 5A to the database of FIG. 6 and calculates the road surface friction coefficient μ _N. At this time, regarding the determination of "asphalt", "concrete", and "gravel", the image of the road surface acquired from the camera of the second road surface friction coefficient sensor 160 and the "asphalt", "concrete" acquired in advance. , From the result of determining the similarity with each image of "gravel", it is determined whether the road surface in front of the vehicle is "asphalt", "concrete", or "gravel".

Further, the second friction coefficient calculation unit 220 acquires in advance the image of the road surface acquired from the camera of the second road surface friction coefficient sensor 160 when it is determined that the road surface in front of the vehicle is "asphalt". From the result of judging the similarity with each image of "new pavement", "normal pavement", "paving wear", and "excessive pavement", the road surface in front of the vehicle is "asphalt" and "new pavement". , "Normal pavement", "Pavement wear", or "Excessive tar". When the second friction coefficient calculation unit 220 determines that the road surface in front of the vehicle is "concrete" or "gravel", the second friction coefficient calculation unit 220 can similarly make a further subdivided determination.

Based on the above, the second friction coefficient calculation unit 220 calculates the road surface friction coefficient μ _N in front of the vehicle from the database of FIG. 6 based on the road surface condition and the vehicle speed. For example, from the image of the camera of the second road surface friction coefficient sensor 160, it is determined that the road surface is "new pavement" of "asphalt", and the vehicle speed detected by the vehicle speed sensor 190 or the wheel speed sensors 127, 128 is When the speed is 40 km / h and the road surface condition is determined to be dry (dry (D)) from the map of FIG. 5A, the value of the road surface friction coefficient μ _N is calculated as 0.8 to 1.0.

In the present embodiment, by combining the first road surface friction coefficient sensor 150 and the second road surface friction coefficient sensor 160, the road surface in front of the vehicle on which the vehicle is not yet traveling is relative to the road surface on which the vehicle is currently traveling. Determines whether or not the vehicle is slippery, and displays information on the inter-vehicle distance according to the determination result.

Specifically, the road surface friction coefficient μ _H of the road surface on which the vehicle is actually traveling and the detection value of the second road surface friction coefficient sensor 160 calculated based on the detection values of the first road surface friction coefficient sensor 150 are used. Compare the road surface friction coefficient μ _N of the road surface in front of the vehicle calculated based on this. When the road surface friction coefficient μ _H is larger than the road surface friction coefficient μ _N and the difference between the road surface friction coefficient μ _H and the road surface friction coefficient μ _N is larger than the constant value μ _C (μ _H − μ _N > μ _C ). , Display for the driver on the meter panel of the vehicle, and display for the driver and the following vehicle on the window of the vehicle (front glass, rear glass, etc.). Then, by these displays, the inter-vehicle distance _LM with the following vehicle is guided to an appropriate distance. The display control unit 240 controls the HUD device 500 and the display device of the meter panel in order to perform these displays.

More specifically, the road surface friction coefficient μ _H is larger than the road surface friction coefficient μ _N , and the difference between the road surface friction coefficient μ _H and the road surface friction coefficient μ _N is larger than the constant value μ _C (μ _H − μ _N > μ _C ). ), And when the inter-vehicle distance LM between the own vehicle and the following vehicle is smaller than the inter-vehicle distance LC that requires attention and larger than the minimum required inter-vehicle distance _{L min} (LC> _LM > _{L min} ). Displays on the rear glass the distance between the vehicle and the following vehicle by the HUD device 500. However, LC and _{L min} are values determined from the road surface friction coefficient μ _H of the own vehicle position and the vehicle speed _VF of the following vehicle.

The inter _- vehicle distance LC that requires attention is determined by the vehicle speed VF of the following vehicle and the margin time _{M 1} . Specifically, the inter _- vehicle distance LC can be obtained from the following equation.
LC = _{M 1 x} VF

However, the margin time M ₁ is a variable determined based on the road surface friction coefficient μ _H of the own vehicle position. As an example, when μ _H ≧ 0.7, M ₁ = 1.5 [s], when 0.4 ≦ μ _H <0.7, M ₁ = 1.85 [s], μ _H <0. In the case of 4, M ₁ = 2.2 [s]. FIG. 7 is a characteristic diagram showing the relationship between _LC and _VF . The value of _LC increases as the value of _VF increases.

The vehicle speed _VF of the following vehicle can be obtained by acquiring the relative speed VR with the following vehicle by the environmental information acquisition unit 202 and comparing it with the vehicle speed _V of the own vehicle. Specifically, the vehicle speed _VF can be obtained from the following equation.
_VF = _VR + V

The minimum required inter-vehicle distance L _min is determined by the vehicle speed VF of the following vehicle and the margin time _{M 2} . Specifically, the inter-vehicle distance L _min can be obtained from the following equation.
L _min = _{M 2} x VF

However, the margin time M ₂ is a variable determined by the road surface friction coefficient μ _H of the own vehicle position. As an example, when μ _H ≧ 0.7, M ₂ = 0.8 [s], when 0.4 ≦ μ _H <0.7, M ₂ = 1.1 [s], μ _H <0. In the case of 4, M ₂ = 1.4 [s]. FIG. 8 is a characteristic diagram showing the relationship between L _min and _VF . The value of L _min increases as the value of _VF increases.

The inter-vehicle distance determination unit 230 determines the inter-vehicle distance _LM between the own vehicle and the following vehicle acquired by the environmental information acquisition unit 202 based on the inter-vehicle distance LC that requires attention and the minimum required inter-vehicle distance _{L min} . It is determined whether or not the condition of LC> _LM > _{L min} is satisfied.

When the road surface friction coefficient μ _N is lower than the constant value constant value μ _C than the road surface friction coefficient μ _H , the road surface in front of the vehicle is more than the road surface at the position of the own vehicle on which the vehicle is traveling. The coefficient of friction is decreasing. In such a case, if a vehicle rushes into the road surface ahead, slippage or the like may occur due to a decrease in the coefficient of friction, so it is desirable to secure a longer distance from the following vehicle. Therefore, if the road surface friction coefficient μ _N is lower than the road surface friction coefficient μ _H by a certain value or more, and the inter-vehicle distance LM between the own vehicle and the following vehicle is less than or equal to the inter-vehicle distance _{L C} that requires caution. , A display indicating the distance between the vehicle and the following vehicle is displayed on the rear glass. The display on the rear glass is performed by controlling the HUD device 500 by the display control unit 240. As a result, the driver of the following vehicle can recognize that the inter-vehicle distance to the vehicle in front is shortened based on the display of the inter-vehicle distance, and tries to secure a longer inter-vehicle distance, so that a rear-end collision or the like occurs. The possibility can be suppressed.

If the inter _- vehicle distance _LM with the following vehicle is greater than or equal to the inter-vehicle distance LC that requires caution (when _LM > LC), a sufficient inter _- vehicle distance with the following vehicle is secured. , It is not necessary to display the inter-vehicle distance for the following vehicle, and the display for the outside of the vehicle is not performed.

The display on the rear glass may be changed stepwise as the inter-vehicle distance _LM becomes shorter. Since this display can be seen from inside and outside the vehicle, it also functions as a display that calls attention to the driver of the own vehicle or the following vehicle. In addition, a display calling attention may be displayed on the meter panel or the windshield for the driver. The display on the windshield can also be performed by the HUD device 500.

When the inter-vehicle distance LM with the following vehicle is the minimum required inter-vehicle distance _{L min} or less (L _min ≧ _LM ), the HUD device 500 displays a warning for the following vehicle on the rear glass. In this case as well, a display calling attention may be displayed on the meter panel or the windshield for the driver.

When the inter-vehicle distance LM with the following vehicle is less than the minimum required inter-vehicle distance _{L min} , the following vehicle is very close and there is a danger of a rear-end collision regardless of the values of the road surface friction coefficient μ _H and μ _N. May occur. Therefore, in this case, a warning is displayed on the rear glass or the like regardless of the values of the road surface friction coefficients μ _H and μ _N. As a result, the possibility of a rear-end collision can be suppressed.

Further, when the vehicle speed V of the own vehicle is _slower than the speed VC of the threshold value for displaying the outside of the vehicle (V < _VC ), the display outside the vehicle is not performed. When the vehicle speed V is _lower than the threshold speed VC, the vehicle is traveling at a relatively slow speed. In such a case, since it is less necessary to display the inter-vehicle distance for the following vehicle, the display for the outside of the vehicle is not performed. In this way, the threshold value VC for deciding whether or not to display the outside of the vehicle is set, and the display for the outside of the vehicle is performed only when the vehicle speed V is _equal to or higher than the threshold value _VC . In situations where the distance between vehicles is inevitably short, do not display outside the vehicle.

The value of _VC of the threshold value is determined by determining the type of road and the degree of congestion based on the environmental information acquired by the environmental information acquisition unit 202, the map information obtained from the navigation device 600, and the like. As an example, VC = 8km / h when driving on an empty highway, _VC = 60km / h when driving on a congested highway, and V when driving on a congested two _- lane national road. Determine the value of _VC , such as _C = 40 km / h.

As described above, by displaying the vehicle in consideration of the surrounding conditions, it is possible to naturally maintain the distance between the vehicle and the following vehicle.

FIG. 9 is a flowchart showing a process performed by the vehicle system 1000 according to the present embodiment. The process shown in FIG. 9 is performed by each component of the control device 200, and is repeatedly performed at predetermined control cycles. First, in step S10, the threshold speed _VC is obtained based on the information obtained from the vehicle exterior sensor 100 or the navigation device 600. In the next step S12, the vehicle speed V is acquired from the vehicle speed sensor 110.

In the next step S14, it is determined whether or not V> _VC , and if V> _VC , the process proceeds to step S16. On the other hand, in the case of V ≦ VC, it is less necessary to display the inter _- vehicle distance, so the process is terminated. In step S16, the vehicle speed _VF of the following vehicle is acquired. In the next step S18, the first friction coefficient calculation unit 210 calculates the road surface friction coefficient μ _H at the position of the own vehicle in which the vehicle is traveling. In the next step S20, the second road surface friction coefficient calculation unit 220 calculates the road surface friction coefficient μ _N in front of the vehicle.

In the next step S22, the inter-vehicle distance _{LC and the minimum inter-vehicle distance L min that require attention are determined based on the vehicle speed VF of the following vehicle and the road surface friction coefficient μ H of the own} vehicle position. In the next step S24, the inter-vehicle distance _LM with the following vehicle is acquired based on the image information outside the vehicle obtained from the vehicle-outside sensor 100.

In the next step S26, it is determined whether or not _LC > _LM , and if _LC > _LM , the process proceeds to step S28. On the other hand, in the case of LC ≤ _LM , it is less necessary to display the inter _- vehicle distance, so the process is terminated (END).

In step S28, it is determined whether or not L _min ≧ _LM , and if L _min ≧ _LM , the process proceeds to step S30. In step S30, a warning for the following vehicle is displayed.

If L _min < _LM in step S28, the process proceeds to step S32. In step S32, it is determined whether or not μ _H − μ _N > μ _C , and if μ _H − μ _N > μ _C , the process proceeds to step S34 to display according to _LM . On the other hand, if μ _H −μ − ≦ μ _C in step S32, the process ends (END).

10 to 12 are schematic views showing an example of display on the rear glass 800 of the vehicle by the HUD device 500. FIG. 10 is a schematic view showing a display on the rear glass according to the inter-vehicle distance. Note that FIGS. 10 and 11 both show the case of LC> _LM > _{L min} , and show the display performed in step S34 of FIG.

Further, in each of FIGS. 10 to 12, the figure on the left side shows how the display 810 on the rear glass 800 seen from the outside of the own vehicle 700 changes according to the distance between the own vehicle 700 and the following vehicle 710. The figure on the right side shows the state where the rear glass 800 is viewed from the inside of the vehicle.

FIG. 10 shows how the trapezoidal display 810 on the rear glass 800 changes according to the distance between the own vehicle 700 and the following vehicle 710. The upper figure in FIG. 10 shows a case where the distance between the own vehicle 700 and the following vehicle 710 is relatively long. In this case, the trapezoidal display 810 on the rear glass 800 is displayed in a plurality of stages.

Further, the middle diagram in FIG. 10 shows a case where the inter-vehicle distance between the own vehicle 700 and the following vehicle 710 is shorter than that in the upper diagram. In this case, the number of trapezoidal display 810s on the rear glass 800 is smaller than that in the upper figure.

Further, the middle diagram in FIG. 10 shows a case where the inter-vehicle distance between the own vehicle 700 and the following vehicle 710 is further shorter than that in the middle diagram. In this case, the number of trapezoidal display 810s on the rear glass 800 is further smaller than in the middle figure. Therefore, the driver of the following vehicle 710 can recognize the inter-vehicle distance based on the number of stages of the trapezoidal display 810 by recognizing the trapezoidal display 810.

Further, as shown in the right side view in FIG. 10, when the rear is viewed from the inside of the vehicle, the display 810 is displayed on the rear glass 800 behind the rear seat 820. Then, the display 810 is arranged below the following vehicle 710 projected on the rear glass 800. As when viewed from the rear, the shorter the inter-vehicle distance, the smaller the number of trapezoidal displays 810. Therefore, the driver of the own vehicle 700 can recognize the inter-vehicle distance based on the number of stages of the trapezoidal display 810 by recognizing the display 810.

FIG. 11 is a schematic view showing another example of the display on the rear glass according to the inter-vehicle distance. Also in FIG. 11, as in the display 810 shown in FIG. 10, the display state of the display 820 changes according to the inter-vehicle distance. In the example shown in FIG. 11, as the inter-vehicle distance becomes shorter, the number of indicators 820 indicating the inter-vehicle distance increases. Therefore, the driver of the following vehicle 710 and the driver 700 of the own vehicle can recognize the inter-vehicle distance by recognizing the display 810.

FIG. 12 is a schematic diagram showing an example of calling attention to a following vehicle. In step S30 of FIG. 9, when the inter-vehicle distance between the own vehicle 700 and the following vehicle 710 becomes shorter than L _min , the warning display 830 for the following vehicle shown in FIG. 12 is performed. In the example shown in FIG. 12, an example in which the display 830 "Caution between vehicles" is displayed on the rear glass 800 is shown. By recognizing the display 830, the driver of the following vehicle can drive while paying attention to the distance between the vehicle and the vehicle in front (own vehicle 800). Further, the driver of the own vehicle 700 can recognize that the following vehicle 710 is approaching by recognizing the display 830 through the rear-view mirror.

FIG. 13 is a schematic diagram showing the principle of displaying the display 810 at an appropriate position when the display 810 is displayed on the rear glass 800. The driver information acquisition unit 204 acquires the driver's head position (x ₁ , y ₁ , z ₁ ) and face orientation θ ₁ from the information obtained from the driver sensor 120. Further, the angle θ ₂ of the rearview mirror 840 is acquired by the rearview mirror sensor 130. It is assumed that the positions (x ₂ , y ₂ , z ₂ ) of the rearview mirror 840 are known. Further, the environmental information acquisition unit 202 acquires the position (x ₃ , y ₃ , z ₃ ) of the following vehicle 710 by the vehicle outside sensor 100. As a result, the driver's head position (x ₁ , y ₁ , z ₁ ) and face orientation θ ₁ , the rearview mirror 840 position (x ₂ , y ₂ , z ₂ ) and angle θ ₂ , and the position of the following vehicle 710 (x). By controlling the position of the display 810 according to _{3 ,} y3 _, z3) and the position and inclination of the rear glass 800, the display 810 is displayed on the rear glass 800 according to the position of the following vehicle 710 projected on the rear glass 800. Can be displayed.

As described above, according to the present embodiment, the road surface friction coefficient μ _H calculated by the first road surface friction coefficient calculation unit 210 and the road surface friction coefficient μ _N calculated by the second road surface friction coefficient calculation unit 220 are used. By displaying the distance between vehicles, it is possible to perform the optimum display according to the road surface condition.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person having ordinary knowledge in the field of the art to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

200 Control device 202 Environmental condition acquisition unit 210 First road surface friction coefficient calculation unit 220 Second road surface friction coefficient calculation unit 240 Display control unit

Claims (9)

A first road surface friction coefficient calculation unit that calculates a first road surface friction coefficient based on a value detected from a hub unit sensor provided on the axle, and a first road surface friction coefficient calculation unit.
A second road surface friction coefficient calculation unit that calculates the second road surface friction coefficient based on the detection value from the non-contact sensor that detects the road surface condition in front of the vehicle in a non-contact manner.
A display control unit that controls the display regarding the inter-vehicle distance based on the first road surface friction coefficient and the second road surface friction coefficient.
Equipped with
In the display control unit, when the first road surface friction coefficient is larger than the second road surface friction coefficient and the difference between the first road surface friction coefficient and the second road surface friction coefficient is larger than a predetermined value. , A vehicle control device comprising controlling a display relating to the inter-vehicle distance. Equipped with an environmental information acquisition unit that acquires the distance to the vehicle behind
In the display control unit, the first road surface friction coefficient is larger than the second road surface friction coefficient, the difference between the first road surface friction coefficient and the second road surface friction coefficient is larger than a predetermined value, and The vehicle control device according to claim 1, wherein the display regarding the inter-vehicle distance is controlled when the distance to the rear vehicle is within a predetermined range. The vehicle control device according to claim 2, wherein the display control unit changes the display regarding the inter-vehicle distance according to the distance to the rear vehicle. The vehicle control device according to claim 3, wherein the display control unit controls the display of an index that increases or decreases according to the distance to the rear vehicle as a display relating to the inter-vehicle distance. The display control unit controls a display for warning to the driver of the rear vehicle or the own vehicle when the distance to the rear vehicle is equal to or less than the lower limit of the predetermined range. The vehicle control device according to any one of Items 2 to 4. The environmental information acquisition unit acquires the position of the rear vehicle in addition to the distance of the rear vehicle, and obtains the position of the rear vehicle.
The display control unit is characterized in that it controls a position on a window portion behind the vehicle, which displays a display relating to the inter-vehicle distance, according to the position of the rear vehicle and the position of the driver of the own vehicle . The vehicle control device according to any one of claims 2 to 5. The vehicle control device according to any one of claims 1 to 6, wherein the display control unit does not display the inter-vehicle distance when the vehicle speed is equal to or less than a predetermined value. The vehicle control according to any one of claims 1 to 7, wherein the display control unit controls a display relating to the inter-vehicle distance displayed on a display device that displays on a window unit behind the vehicle. Device. The step of calculating the first road surface friction coefficient based on the detected value from the hub unit sensor provided on the axle, and
A step of calculating the second road surface friction coefficient based on the detection value from the non-contact sensor that non-contactly detects the road surface condition in front of the vehicle, and
A step of controlling the display regarding the inter-vehicle distance based on the first road surface friction coefficient and the second road surface friction coefficient, and
Equipped with
In the step of controlling the display regarding the inter-vehicle distance, the first road surface friction coefficient is larger than the second road surface friction coefficient, and the difference between the first road surface friction coefficient and the second road surface friction coefficient is a predetermined value. A vehicle control method, characterized in that the display relating to the inter-vehicle distance is controlled when the coefficient is larger than the above.

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