WO2013027112A2

WO2013027112A2 - Driving support device and driving support method

Info

Publication number: WO2013027112A2
Application number: PCT/IB2012/001622
Authority: WO
Inventors: Yuki Ogawa
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2011-08-24
Filing date: 2012-08-22
Publication date: 2013-02-28
Also published as: JP2013045306A; WO2013027112A3; JP5459278B2

Abstract

A driving support device has an infrastructure communication section that obtains signal cycle information of the respective traffic signals disposed at two or more points in a traveling direction of the vehicle, a position calculation section that calculates relative position information representing relative positions between a present position of the vehicle and each of the plurality of points, a target vehicle speed control section that calculates, as reference target vehicle speed ranges, respective speed ranges where the vehicle can pass the respective points while the traffic signals are in a passage allowed indication state where the traffic signal indicates based on the relative position information and the signal cycle information and that determines respective target vehicle speed information based on the reference target vehicle speed ranges, and a target vehicle speed display section that displays target vehicle speed information about the plurality of points.

Description

DRIVING SUPPORT DEVICE AND DRIVING SUPPORT METHOD

BACKGROUND OF THE INVENTION

1. Field of the Invention

[0001] The present invention relates to a driving support device and a driving support method.

2. Description of Related Art

[0002] Some vehicles such as automobiles have a driving support device installed therein for supporting driving of a driver. For example, Japanese Patent Application Publication 2009-289007 (JP 2009-289007 A) discloses a vehicle travel speed indication method that comparatively indicates an actual travel speed of a vehicle as a relative value to a reference value with respect to a recommended travel speed or a corrected recommended travel speed as the reference value which is fixedly indicated on a display screen. Further, Japanese Patent Application Publication 2009-9288 (JP 2009-9288 A) discloses a device that obtains traffic signal switching information of a plurality of traffic signals, calculates which intervals in a route to a destination a vehicle travels at which recommended speeds, and outputs the recommended speeds to a driver.

[0003] The system disclosed in JP 2009-289007 A or JP 2009-9288 A provides the indication of the recommended travel speed and can thereby inform the driver of a travel condition in which the driver can pass the traffic signal. However, the device disclosed in JP 2009-289007 A or JP 2009-9288 A may cause the driver to experience difficulty in noticing a traveling speed which enables passage of a plurality of traffic signals.

SUMMARY OF THE INVENTION

[0004] The present invention is to provide a driving support device and a driving support method that can indicate information which a driver easily notice and can appropriately support driving.

[0005] A first aspect of the present invention provides a driving support device for supporting driving of a vehicle, the device including: an infrastructure communication section that obtains signal cycle information concerning switching among indications of the respective traffic signals which are disposed at two or more points in a traveling direction of the vehicle; a position calculation section that calculates relative position information which represents relative positions between a present position of the vehicle and each of the plurality of points; a target vehicle speed control section that calculates, as reference target vehicle speed ranges, respective speed ranges in which the vehicle can pass the respective points while the traffic signals are in a passage allowed indication state where the traffic signal indicates that passage of the vehicle is allowed, based on the relative position information and the signal cycle information and that determines respective target vehicle speed information based on the reference target vehicle speed ranges; and a target vehicle speed display section for displaying the target vehicle speed information about the plurality of points which is determined by the target vehicle speed control section. .

[0006] Further, in the driving support device in accordance with the first aspect, the signal cycle information may be cycles in which indications of the traffic signals are switched or timings in which the indications of the traffic signals change.

[0007] Further, in the driving support device in accordance with the first aspect, the target vehicle speed control section may prevent an indication of the target vehicle speed information about a second point on the target vehicle speed display section if a difference between the target vehicle speed information about a first point that is the point which is closer to the vehicle in the traveling direction and the target vehicle speed information about the second point that is the point which is more distant than the first point in the traveling direction exceeds a preset threshold.

[0008] Further, in the driving support device in accordance with the first aspect, the difference between the target vehicle speed information about the first point and the target vehicle speed information about the second point may be a difference between an upper limit value of the target vehicle speed information about the first point and a lower limit value of the target vehicle speed information about the second point.

[0009] Further, in the driving support device in accordance with the first aspect, the target vehicle speed control section may prevent the indication of the target vehicle speed information about the second point on the target vehicle speed display section if a distance between the first point which is closer to the vehicle in the traveling direction and the second point which is more distant than the first point in the traveling direction exceeds a preset threshold.

[0010] Further, in the driving support device in accordance with the first aspect, the target vehicle speed control section may prevent the indication of the target vehicle speed information about the second point if a distance between the vehicle and the second point exceeds a threshold value.

[0011] Further, in the driving support device in accordance with the first aspect, the target vehicle speed control section may determine whether the target vehicle speed information about the first point is indicated on the target vehicle speed display section base on a preset condition.

[0012] Further, in the driving support device in accordance with the first aspect, the target vehicle speed control section may prevent the indication of the target vehicle speed information about the second point on the target vehicle speed display section if the target vehicle speed control section determines to prevent an indication of the target vehicle speed information about the first point.

[0013] Further, in the driving support device in accordance with the first aspect, the target vehicle speed control section may prevent the indication of the target vehicle speed information about the second point on the target vehicle speed display section if the target vehicle speed control section determines that the vehicle cannot pass the first point while the traffic signal at the first point is in the passage allowed indication state based on the reference target vehicle speed range for the first point.

[0014] Further, the driving support device in accordance with the first aspect further includes a vehicle speed sensor that detects the travel speed of the vehicle. In the driving support device, the target vehicle speed control section may set an indication upper limit speed which is an upper limit value of a travel speed range which is the target vehicle speed information based on a present vehicle speed detected by the vehicle speed sensor, and the target vehicle speed control section may determine that the vehicle cannot pass the point while the traffic signal is in the passage allowed indication state if an entire range of the reference target vehicle speed range exceeds the indication upper limit speed.

[0015] Further, the driving support device in accordance with the first aspect further includes an information obtainment section that obtains a speed limit of a road on which the vehicle is traveling. In the driving support device, the target vehicle speed control section may set the speed limit as the indication upper limit speed and may determine that the vehicle cannot pass the point while the traffic signal is in the passage allowed indication state if the entire range of the reference target vehicle speed range exceeds the indication upper limit speed.

[0016] Further, in the driving support device in accordance with the first aspect, the target vehicle speed control section may set the target vehicle speed information to speed information being equal to or lower than the indication upper limit speed.

[0017] Further, in the driving support device in accordance with the first aspect, the target vehicle speed control section may set the target vehicle speed information about the point to speed information including zero km/h if the vehicle cannot pass the point.

[0018] Further, in the driving support device in accordance with the first aspect, the target vehicle speed information may be information about a speed range having upper limit and lower limit speeds differing from each other.

[0019] Further, in the driving support device in accordance with the first aspect, the target vehicle speed control section may indicate speeds of the target vehicle speed information about the second point which overlap with the target vehicle speed information about the first point on the target vehicle speed display section as the target vehicle speed information about the second point.

[0020] A second aspect of the present invention provides a driving support method for supporting driving of a vehicle, the method including: obtaining signal cycle information concerning switching among indications of the respective traffic signals which are disposed at two or more points in a traveling direction of the vehicle; calculating relative position information which represents relative positions between a present position of the vehicle and each of the plurality of points; calculating, as reference target vehicle speed ranges, respective speed ranges in which the vehicle can pass the respective points while the traffic signals are in a passage allowed indication state where the traffic signal indicates that passage of the vehicle is allowed based on the relative position information and the signal cycle information; determining target vehicle speed information based on the reference target vehicle speed ranges; and displaying the target vehicle speed information about the plurality of points.

[0021] The driving support device and the driving support method in accordance with the present invention provide an effect such that they can indicate information which a driver easily notices and which can appropriately support driving.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

FIG. 1 is an explanatory view illustrating an example of a driving support system in accordance with the embodiment;

FIG. 2 is a block diagram illustrating a schematic configuration of a vehicle in which the driving support device in accordance with the embodiment is installed;

FIG. 3 is a schematic diagram illustrating an example of a speed indication area of a display device;

FIG. 4 is a flowchart illustrating an example of a process of the driving support device; FIG. 5 is a schematic diagram illustrating an example of the speed indication area of the display device;

FIG. 6 is a schematic diagram illustrating an example of the speed indication area of the display device;

FIG. 7 is a schematic diagram illustrating an example of the speed indication area of the display device;

FIG. 8 is a flowchart illustrating another example of the process of the driving support device;

FIG. 9 is a schematic diagram illustrating an example of the speed indication area of the display device;

FIG. 10 is a schematic diagram illustrating an example of the speed indication area of the display device;

FIG. 11 is a flowchart illustrating another example of the process of the driving support device;

FIG. 12 is a schematic diagram, illustrating an example of the speed indication area of the display device;

FIG. 13 is a schematic diagram illustrating another example of the speed indication area of the display device; and

FIG. 14 is an explanatory view illustrating an example of a process of the driving support device.

DETAILED DESCRIPTION OF EMBODIMENTS

[0023] A driving support device in accordance with an embodiment of the present invention will be described hereinafter in detail with reference to drawings. It should be understood that this embodiment does not limit the present invention.

[0024] The embodiment will be described with reference to FIGs. 1 to 6. This embodiment relates to a driving support system having a vehicle in which a driving support device is installed. First, a configuration of the driving support system having the vehicle in which the driving support device is installed will be described with reference to FIGs. 1 to 3. FIG. 1 is an explanatory view illustrating an example of the driving support system in accordance with this embodiment. FIG. 2 is a block diagram illustrating a schematic configuration of the vehicle in which the driving support device in accordance with the embodiment is installed. FIG. 3 is a schematic diagram illustrating an example of a speed indication area of a display device.

[0025] The driving support system 1 shown in FIG. 1 has a plurality of vehicles 10, a plurality of traffic signals 12, 12a, a plurality of infrastructure information sending devices 14, and a GPS satellite 16. The driving support system 1 is a system that supports driving of a driver on the basis of information that the plurality of vehicles 10 in which a driving support system 19 which will be described later is installed detect the relationships with the other vehicles 10, access the infrastructure information sending device 14 and the GPS satellite 16, and thereby obtain,

[0026] The vehicle 10 is a vehicle which can travel on a road such as an automobile or a truck. The vehicle 10 can travel on a road on which the traffic signals 12, 12a are disposed. A configuration of the vehicle 10 will be described later.

[0027] The traffic signals 12, 12a are lighting devices disposed at intersections. The traffic signal 12 includes lighting sections of three colors that are green, yellow, and red. Further, the traffic signal 12a includes lighting sections (arrow light apparatus) that display arrows in addition to the lighting sections of three colors that are green, yellow, and red. The traffic signals 12, 12a may be disposed in each traveling direction of the vehicle which travels on the road. The traffic signal 12 switches the lighting sections of the three colors that are green, yellow, and red to be illuminated and indicates the state where the vehicle 10 is allowed to pass the intersection in its traveling direction on the road or the state where the vehicle 10 is prohibited from passing, in other words, the vehicle 10 should stop. FIG. 1 illustrates the driving support system 1 in which the traffic signals 12, 12a are disposed at the intersections. However, the positions to dispose the traffic signals 12, 12a are not limited to intersections. For example, the traffic signals 12, 12a may be disposed at pedestrian crossings.

[0028] The infrastructure information sending device 14 sends infrastructure information such as road information of the road on which the vehicles 10 travels and traffic signal information about the traffic signals 12, 12a provided ahead in the traveling direction of the vehicle 10. The infrastructure information sending device 14 of this embodiment is disposed at each intersection and sends the infrastructure information to the vehicles 10 traveling in a certain range around the infrastructure information sending device 14 by wireless communication. Here, the road information typically includes information such as speed limits of the road on which the vehicle 10 travels and the positions of stop lines at intersections. The traffic signal information typically includes traffic signal cycle information such as illumination cycles the illuminated lighting section of the traffic signals 12, 12a change among green, yellow, and red or the timings in which the indications of the traffic signals change. The infrastructure information sending device 14 may be provided at each of the traffic signals 12, 12a. Alternatively, the single infrastructure information sending device 14 may be provided for a plurality of intersections.

[0029] The GPS satellite 16 is a satellite that outputs GPS signals required for positional detection by GPS (GPS: Global Positioning System). Although FIG.1 shows the . driving support system 1 having the single GPS satellite 16, the driving support system 1 has at least the three GPS satellites 16. A device that detects a position by GPS receives GPS signals output from at least three GPS satellites 16, . compares the received GPS signals, and thereby detects the position of the own device.

[0030] Next, the vehicle 10 in which the driving support device 19 is installed will be described with reference to FIG. 2. In the driving support system 1 shown in FIG. 1 , all the vehicles are the vehicles 10 in which the driving support system 19 is installed. However, it is sufficient that at least one of the vehicles 10 has the driving support system 19 installed therein. In other words, in the driving support system 1 , vehicles that has no driving support device 19 may travel ahead or behind the vehicle 10 in which the driving support device 19 is installed.

[0031] The vehicle 10 has an ECU 20, a memory section 22, an accelerator actuator 24, a brake actuator 26, an automotive navigation system 28, a speaker 30, a GPS communication section 32, an onboard camera 34, a millimeter-wave radar 36, a infrastructure communication section 38, a vehicle speed sensor 40, a display device 42, an ACC switch 44, and a PCS switch 46. The ECU 20, the memory section 22, the accelerator actuator 24, the brake actuator 26, the automotive navigation system 28, the speaker 30, the GPS communication section 32, the onboard camera 34, the millimeter-wave radar 36, the infrastructure communication section 38, the vehicle speed sensor 40, the display device 42, the ACC switch 44, and the PCS switch 46 of the vehicle 10 also serve as the driving support device 19 of the vehicle 10. Further, the vehicle 10 includes parts that a vehicle in general includes such as a vehicle body, a drive source, a brake system, and operation sections (for example, a steering wheel, an accelerator pedal, and a brake pedal), other than the parts described above.

[0032] The ECU 20 is an electronic control unit and controls the parts of the vehicle 10 such as the accelerator actuator 24, the brake actuator 26, the automotive navigation system 28, the speaker 30, the GPS communication section 32, the onboard camera 34, the millimeter-wave radar 36, the infrastructure communication section 38, the vehicle speed sensor 40 and the display device 42. The ECU 20 controls operation of each of the parts on the basis of information obtained by the GPS communication section 32, the onboard camera 34, the millimeter-wave radar 36, the infrastructure communication section 38, and the vehicle sensor 40 and operations by the driver or the like that are input from operation sections such as the ACC switch 44, the PCC switch 46, and the accelerator pedal and the brake pedal that are not shown. Further, the ECU 20 has a vehicle interval control section 20a, a vehicle maintenance control section 20b, and a target vehicle speed control section 20c. The target vehicle speed control section 20c will be described later.

. [0033] The memory section 22 is a storage device such as a memory and stores conditions and data required for various processes by the ECU 20 and various programs that are executed by the ECU 20. Further, the memory section 22 stores a map information database 22a. The map information database 22a stores information required for travel of the vehicle (such as maps, straight roads, curved roads, upward and downward slopes, highways, sags, and tunnels). Further, the map information database 22a includes a map data file, an intersection data file, a node data file, and a road data file. The ECU 20 accesses the map information database 22a to read out required information.

[0034] The accelerator actuator 24 controls outputs of power sources of the vehicle 10 such as an engine and a motor. For example, the accelerator actuator 24 is capable of controlling an intake amount into the engine, an intake timing, an ignition timing, a frequency and a voltage value provided by the motor, and the like. The accelerator actuator 24 is electrically connected to the ECU 20. The operation of the accelerator actuator 24 is controlled by the ECU 20. For example, the ECU 20 actuates the accelerator actuator 24 in response to accelerator control signals and thereby adjusts the intake amount into the engine, the intake timing, the ignition timing, the frequency and the voltage value provided by the motor. In other words, the accelerator actuator 24 is a device for automatically controlling the driving force provided by the power sources and receives the accelerator control signals output from the ECU 20 and drives each section, thereby controlling driving conditions and generating desired driving force. As described above, the accelerator actuator 24 controls the driving force applied to the vehicle 10 and thereby adjusts its acceleration.

[0035] The brake actuator 26 controls operation of the brake device installed in the vehicle 10. For example, the brake actuator 26 controls the hydraulic pressure of a wheel cylinder provided in the brake device. The brake actuator 26 is electrically connected to the ECU 20. The operation of the brake actuator 26 is controlled by the ECU 20. The ECU 20 actuates the brake actuator 26 in response to brake control signals and thereby adjusts the brake hydraulic pressure of the wheel cylinder. In other words, the brake actuator 26 is a device for automatically controlling the braking force applied by the brake and receives the brake control signals output from the ECU 20 and operates a solenoid and a motor of a mechanism that supplies a hydraulic fluid to the wheel cylinder, thereby controlling the brake hydraulic pressure and generating desired braking force. As described above, the brake actuator 26 controls the braking force applied to the vehicle 10 and thereby adjusts its deceleration. [0036] The automotive navigation system 28 is a device for guiding the vehicle 10 to a prescribed destination. The automotive navigation system 28 is capable of two-way communication with the ECU 20. The automotive navigation system 28 includes a display section and causes the display section to display map information around the vehicle on the basis of information stored in the map information database 22a and the information about a present position that is obtained by the GPS communication section 32 which will be described later. Further, the automotive navigation system 28 detects a route to the destination by use of information stored in the map information database 22a, the information about the present position that is obtained by the GPS^* communication section 32 which will be described later, and the destination information input by the driver or the like and causes the display section to display the detected route information. The automotive navigation system 28 may include a map information database and a GPS communication section in .the own system separately from the map information database 22a and the GPS communication section 32 and may thereby provide route guidance and the information about the present position.

[0037] The speaker 30 outputs sounds in the vehicle 10. The speaker 30 outputs sounds corresponding to sound signals sent by the ECU 20.

[0038] The GPS communication section 32 receives the respective GPS signals output from the plurality of GPS satellites 16. The GPS communication section 32 sends the received GPS signals to ECU 20. The ECU 20 analyzes the plurality of received GPS signals and thereby detects positional information of the own unit.

[0039] The onboard camera 34 is an image capturing device that is disposed in a front portion of the vehicle 10 and obtains images ahead (ahead in the traveling direction) of the vehicle 10. The onboard camera 34 sends the obtained images ahead of the vehicle 10 to the ECU 20. The ECU 20 analyzes the images obtained by the onboard camera 34 and thereby can obtain information about the state of the area ahead of the vehicle 10, in other words, whether the vehicle has the other vehicle 10 ahead, the vehicle 10 is close to the traffic signals 12, 12a, the vehicle 10 is close to an intersection, and the like. [0040] The millimeter-wave radar 36 is a sensor to measure the vehicle interval between the own vehicle and the other vehicle ahead (the vehicle ahead of the vehicle 10). The millimeter-wave radar 36 emits electric waves of millimeter-wave band forward of the vehicle 10 and receives the electric waves that have reflected on an object (the vehicle ahead) and returned to the own radar among the emitted electric waves. The millimeter- wave radar 36 compares the output conditions of the emitted electric waves and the detection results of the received electric waves and thereby calculates the interval to the vehicle ahead. Further, the millimeter- wave radar 36 may detect the distance to an obstacle ahead of the own vehicle. The millimeter- wave radar 36 sends the information about the calculated interval to the vehicle ahead to the ECU 20. In this embodiment, the millimeter- wave radar 36 is used as the sensor for measuring the vehicle interval between the own vehicle to the vehicle ahead (the vehicle ahead of the vehicle 10). However, various kinds of sensors that can measure the distance between the vehicle 10 and an object ahead of the vehicle 10 may be used. For example, the vehicle 10 and the driving support device 19 may employ a laser radar sensor instead of the millimeter-wave radar 36.

[0041] The infrastructure communication section 38 performs wireless communication with the infrastructure information sending device 14 described above. The infrastructure communication section 38 obtains the infrastructure information sent by the infrastructure information sending device 14 and sends the obtained infrastructure information to the ECU 20. The infrastructure communication section 38 constantly communicates with the infrastructure information sending devices 14 which are capable of communication and may thereby obtain the infrastructure information, communicates with the infrastructure information sending devices 14 at certain time intervals and may thereby obtains the infrastructure information, or when the new infrastructure information sending device 14 becomes capable of communication, communicates with this infrastructure information sending device 14 and may thereby obtain the infrastructure information.

[0042] The vehicle speed sensor 40 detects the vehicle speed of the vehicle 10. The vehicle speed sensor 40 sends the information about the obtained vehicle speed to the ECU 20.

[0043] The display device 42 is a display device that displays various kinds of information to be informed to the driver, and is an instrument panel disposed on a dash board of the vehicle 10, for example. The display device 42 may be a liquid crystal display device or may be a display device having various measuring instruments disposed therein. The display device 42 displays information such as a remaining fuel amount, output of the drive source (engine speed), open or close states of doors, and states of use of seatbelts. The display device 42 includes a speed indication area 48 which indicates the vehicle speed.

[0044] As shown in FIG. 3, the speed indication area 48 has a scale display section 50, and a needle 52. The scale display section 50 has an arc shape and has a scale between zero km/h and 160 km/h. The needle 52 points the vehicle speed as a measurement result and points 40 km/h in FIG. 3. The speed indication area 48 is an analog meter. The position on the scale display section 50 which the needle 52 points changes in response to the present vehicle speed. Accordingly, the driver checks the position of the needle 52 on the speed indication area 48 and can thereby notice the result of the detection of the present vehicle speed.

[0045] Next, the target vehicle speed control section 20c will be described. The target vehicle speed control section 20c calculates a reference target vehicle speed range on the basis of information obtained by each section of the vehicle _.10, modifies the calculated reference target vehicle speed range calculated on the basis of a preset conditions and thereby determines a target vehicle speed range (target speed range), and causes the speed indication area 48 of the display device 42 to indicate the determined target vehicle speed range. Specifically, the target vehicle speed control section 20c calculates the speed range (reference target vehicle speed range) which is the travel speed range which is required for passage of the traffic signals 12, 12a while they are in the green light state (in other words, the traffic signals are in a passage allowed indication state), on the basis of (1) the traffic signal cycle information obtained by the infrastructure communication section 38 about switching among the indications of the traffic signals such as the illumination cycle in which the indications of the traffic signals 12, 12a disposed at each object to be passed (intersection or pedestrian crossing) are switched and the timings at which the indications of the traffic signals change; (2) and information such as relative positions which are the distances between the vehicle 10 and the traffic signals 12, 12a (accurately, the distances to the intersection or the pedestrian crossings (also referred to as "object to be passed" and "traffic signal point") at which the traffic signals 12, 12a are disposed) at each of the objects to be passed (traffic signal points). Further, the target vehicle speed control section 20c calculates and determines the target vehicle speed range on the basis of the calculated reference target vehicle speed range and preset conditions for each of the calculated target vehicle speed range. The speed indication area 48 is caused to indicate the calculated target vehicle speed range (recommended travel speed , range). In other words, the speed indication area 48 is caused to indicate the travel speed range in which the target speed range is recommended as a present travel speed. Further, the target vehicle speed control section 20c causes the speed indication area 48 to indicate the plurality of target vehicle speed range when the target speed ranges for passing the plurality of traffic signal points are calculated. An example of the preset conditions is comparing the present vehicle speed with the target vehicle speed and setting a speed range which satisfies the relationship set with respect to the present vehicle speed as the target vehicle speed. As described above, the target vehicle speed control section 20c performs green wave support which is control for advising the driver of the vehicle speed in order to reduce the frequency in which the vehicle 10 stops at the red lights. The passage allowed indication state of the traffic signal is a state where the traffic signal provides the indication that passage of the object route is allowed. However, such an indication is not limited to the green light indication, but includes the indication of the arrow light apparatus. The green light indication is the state where, for example, the blue, green, or another color which indicates that the vehicle is allowed to pass is illuminated among the illuminated sections of the traffic signal. Further, the yellow light indication may be set as the passage allowed indication state of the traffic signal.

[0046] The control executed by the target vehicle speed control section 20c of the ECU 20 of the vehicle 10 will be described hereinafter more in detail with reference to FIGs. 4 to 6. FIG. 4 is a flowchart illustrating an example of a process of the driving support device. FIGs. 5 and 6 are each a schematic diagram illustrating an example of the speed indication area of the display device.

[0047] The target vehicle speed control section 20c of the ECU 20 determines whether the green wave support is possible with the traffic signal (traffic signal point) which the vehicle next passes in step S 12. Specifically, the target vehicle speed control section 20c determines whether the information required for calculating the target vehicle speed range has been obtained for the traffic signal disposed at the closest traffic signal point (first traffic signal point) in the traveling direction (in a traveling route) and the conditions of allowing indication of the target vehicle speed range are satisfied. The information required for calculating the target vehicle speed range are such as the infrastructure information, information about the present position, and the map information. The infrastructure information is such as the illumination cycle or change timing of the traffic signal of the traffic signals 12, 12a as the object to be passed which, is described above. The information about the present position is the information required for calculating the distance between the vehicle 10 and the traffic signals 12, 12a. The map information is the information containing the positional information of the traffic signals 12, 12a. Further, examples of the conditions of allowing indication of the target vehicle speed range are the distances (distances to the object intersections) between the vehicle 10 and the traffic signals 12, 12a being a certain distance or longer, the present vehicle speed of the vehicle 10 being a certain speed or higher, and the like. If the distance (distance to the object intersection or the like) between the vehicle 10 and the traffic signals 12, 12a is shorter than the certain distance, the target vehicle speed control section 20c determines that it does not perform the green wave support since if the target vehicle speed range is indicated, it is difficult for the driver to drive in response to the indication. Further, if the present vehicle speed of the vehicle 10 is lower than the certain speed, the target vehicle speed control section 20c determines that it does not perform the green wave support since there is high possibility that a traffic jam has occurred on the road on which the vehicle is traveling and the travel speed may be limited, or the traffic may have been stopping or may have stopped for some reasons, and if the target vehicle speed range is indicated, it is difficult for the driver to drive in response to the indication. If the target vehicle speed control section 20c determines that the support is not possible (No) in step S I 2, in other words, the target vehicle speed range for the traffic signal point to be next passed cannot be calculated , the process is terminated.

[0048] Further, if it is determined that the support is possible (Yes) in step S I 2, the target vehicle speed control section 20c determines whether the cycle (traffic signal cycle) of the traffic signal to be second passed (the traffic signal disposed at the traffic signal point which is second passed in the traveling direction) in step SI 4. In other words, the target vehicle speed control section 20c determines whether the green wave support is possible with the traffic signal to be second passed. The target vehicle speed control section 20c determines that the conditions other than the traffic signal cycle of the traffic signal to be second passed are satisfied when the determination is Yes . in step S 12 and then does not make the determination about the conditions in step SI 4. That is, the target vehicle speed control section 20c obtains the traffic signal cycle of the traffic signal to be second passed and thereby allows the green wave support for the traffic signal to be second passed. If the target speed control section 20c determines that the support is not possible (No) in step SI 2, in other words, the support cannot be performed, the process is terminated.

[0049] If the target vehicle speed control section 20c determines that the cycle of the traffic signal to be second passed has not been obtained (No) in step SI 4, in other words, the target vehicle speed range for the traffic signal point to be second passed cannot be calculated, the process progresses to step S20.

[0050] If the target vehicle speed control section 20c determines that the cycle of the traffic signal to be second passed has been obtained (Yes) in step S 14, the target vehicle speed control section 20c determines whether the distance to the traffic signal to be second passed < a threshold value in step SI 6. The distance to the traffic signal to be second passed is the distance between the present vehicle position and the traffic signal point (intersection or pedestrian crossing). The threshold value is a preset value. As the threshold value, a distance in a range where the traffic signal can be visually recognized, a distance through which the vehicle can go at an average legal speed limit in a certain time period (for example, ten seconds), or the like can be used.

[0051] If the target vehicle speed control section 20c determines that the distance to the traffic signal to be second passed < the threshold value (Yes) in step S 16, in other words, the distance between the present vehicle position and the traffic signal point is shorter than the distance of the threshold value, the target vehicle speed control section 20c indicates the target vehicle speed ranges for the two traffic signals in step SI 8. That is, as the passage support indication, the target vehicle speed control section 20c calculates the reference target vehicle speed range for the traffic signal to be next passed, in other words, the traffic signal to be first passed, determines the target vehicle speed range (hereinafter also referred to as "first target vehicle speed range") on the basis of the calculated reference target vehicle speed range, further calculates the reference target vehicle speed range for the traffic signal to be second passed, and determines the target vehicle speed range (hereinafter also referred to as "second target vehicle speed range") on the basis of the calculated reference target vehicle speed range. Here, the reference target vehicle speed range is the vehicle speed range in which the vehicle can pass the object intersection, pedestrian crossing, or the like, which is in other words the traffic signal point, namely, the vehicle speed range in which the vehicle can pass the object intersection, pedestrian crossing, or the like while the object traffic signal is the , green light. The target vehicle speed control section 20c indicates the two determined target vehicle speed ranges in the speed indication area.

[0052] For example, the target vehicle speed control section 20c displays a speed indication area 48a shown in FIG. 5. The speed indication area 48a indicates markers 62 and 64 in the speed range on the scale display section 50 which overlaps with the target vehicle speed ranges. The marker 62 indicates the first target vehicle speed range, and the marker 64 indicates the second target vehicle speed range. Here, in the speed indication area 48a shown in FIG. 5, the marker 62 is indicated in the speed range of 15 km/h to 40 km/h on the scale display section 50. The marker 64 is indicated in the speed range of 30 km/h to 50 km/h on the scale display section 50. Further, in the speed indication area 48a, the marker 62 is disposed on an inner peripheral side than the marker 64. Here, the target vehicle speed control section 20c indicates the target vehicle speed range corresponding to the traffic signal point which is closer to the vehicle on the inner peripheral side of the scale display section 50. In other words, when the first target vehicle speed range corresponding to the traffic signal point at which the first traffic signal closer than the traffic signal to be second passed is disposed and the second target vehicle speed range corresponding to the traffic signal to be second passed are indicated on the scale display section 50, the first target vehicle speed range is indicated on the inner peripheral side than the position where the second target vehicle speed range is indicated on the scale display section 50. Accordingly, the driver checks the speed indication area 48a and can thereby notice that the marker 62 indicates the first target vehicle speed range and the marker 64 indicates the second target vehicle speed range. Further, the driver can notice that the first target vehicle speed range which is the speed range required for passing the next traffic signal point, in other words, the traffic signal point to be first passed is 15 km/h to 40 km/h and that the second target vehicle speed range which is the speed range required for passing the second traffic signal point is 30 km/h to 50 km/h.

[0053] Here, it has been described that the distance to the traffic signal is the distance between the present vehicle position and the traffic signal point to be second passed. However, the present invention is not limited to this. An example of the distance to the traffic signal to be second passed may be the distance between the traffic signal to be first passed and the traffic signal to be second passed. In other words, the distance to the traffic signal to be second passed may be the distance between the. closer traffic signal point in the traveling direction of the vehicle and the more distant traffic signal point than the closer traffic signal point in the traveling direction.

[0054] In a case that the speed indication area 48a has the scale display section 50 displayed as an image on a liquid crystal display device, the markers 62 and 64 may overlap therewith as images displayed on the liquid crystal display device. Further, in a case that the speed indication area 48a has the scale display section 50 printed- in ink or the like, illuminated sections are disposed in a portion on which the scale is displayed in the scale display section 50, the illuminated sections of the target speed ranges are illuminated, and the markers 62 and 64 may thereby be indicated. As described above, the target vehicle speed control section 20c indicates the determined target vehicle speed ranges by the markers 62 and 64 overlapping with the scale display section 50, thereby allowing the user to notice the determined target vehicle speed ranges. The target vehicle speed control section 20c performs the process shown in step SI 8 and thereafter progresses to step S22.

[0055] If the target vehicle speed control section 20c determines No in step S 14 and No in step SI 6, the target vehicle speed control section 20c indicates the target vehicle speed range for only the traffic signal to be next passed. In other words, as the passage support indication, the. target vehicle speed control section 20c calculates the reference target vehicle speed range for the traffic signal to be next passed and determines the target vehicle speed range (hereinafter also referred to as "first target vehicle speed range") on the basis of the calculated reference target vehicle speed range. The target vehicle speed control section 20c indicates the single determined target vehicle speed range in the speed indication area. Accordingly, the target vehicle speed range for the traffic signal to be second passed is not indicated in the speed indication area.

[0056] For example, the target vehicle speed control section 20c displays a speed indication area 48b shown in FIG. 6. The speed indication area 48b indicates a marker 66 in the speed range on the scale display section 50 which overlaps with the target vehicle speed range. The marker 66 indicates the first target vehicle speed range. Here, in the speed indication area 48b shown in FIG. 6, the marker 66 is indicated in the speed range of 30 km/h to 50 km/h on the scale display section 50. Accordingly, the driver checks the speed indication area 48b and can thereby notice that the first target vehicle speed range which is the speed range required for passing the next traffic signal point is 30 km/h to 50 km/h. The speed indication^ area 48b shown in FIG. 6 and the speed indication area 48a shown in FIG. 5 indicate the first target vehicle speed ranges having different values since the conditions are different. The target vehicle speed control section 20c performs the process shown in step S20 and thereafter progresses to step S22.

[0057]^' The target vehicle speed control section 20c performs the process of step SI 8 or step S20 and thereafter determines whether indication terminating conditions are satisfied in step S22. Here, the indication terminating conditions are conditions for terminating the indication of the preset target vehicle speed range. Examples of those may include cases that the distance between the vehicle and the intersection (the object traffic signal) becomes a prescribed distance or shorter, that the vehicle speed falls out a prescribed range, and that a prescribed time period has passed after the target vehicle speed range was indicated. If the target vehicle speed control section 20c determines that the conditions are not satisfied (No) in step S22, the process progresses to step SI 2, and the processes described above are repeated. In other words, the target vehicle speed control section 20c executes the determination whether the target vehicle speed range for each of the traffic signals can be indicated and the calculation of the target vehicle speed range and again indicates the target vehicle speed range for the object. If the target speed control section 20c determines that the conditions are satisfied (Yes) in step S22, the process is terminated.

[0058] The driving support device 19 (and the vehicle 10 having that, the driving support system 1) calculates the target vehicle speed ranges for the respective intervals among the plurality of traffic signals in the traveling direction (in the direction to proceed), indicates the target vehicle speed ranges sequentially from those for the traffic signals which are positioned closer in the traveling direction, and can thereby clearly inform the driver of the target vehicle speed ranges for passing the plurality of traffic signal points. In other words, the indications in the speed indication area 48 are made sequentially from the target vehicle speed range for the traffic signal which is positioned the closest to the vehicle. Further, the driving support device 19 calculates the target vehicle speed range for each of the plurality of traffic signal points with the present position of the vehicle 10 being the origin and can thereby facilitate the calculation of the target vehicle speed ranges. Accordingly, the driver checks the speed indication area and can thereby easily understand that the present vehicle speed should be changed to which speed to pass the object traffic signal point.

[0059] Further, if there is a traffic signal point for which the green wave support cannot be performed, in other words, the target vehicle speed range cannot be detected or indicated, the driving support device 19 prevents indication of the target vehicle speed range for the traffic signal point which is more distant than the concerned traffic signal point and can thereby clearly indicate the target vehicle speed range to the driver.

[0060] Further, if the distance to the object traffic signal point is a certain distance or longer, the driving support device 19 prevents indication of the target vehicle speed range for the traffic signal point and can thereby prevent indications of the target vehicle speed ranges more than a required number. This allows the driving support device 19 to clearly indicate the. target vehicle speed ranges to the driver. In other words, the driving support device 19 prevents indications of the target vehicle speed ranges for the distant traffic signals for which the target vehicle speed range can be indicated when the vehicle approaches closer. This allows clear indication of the target vehicle speed range to the driver and allows reduction in the possibility of causing the driver to experience unnecessary stress.

[0061] Further, the driving support device 19 indicates the target vehicle speed range for the closer traffic signal in the traveling direction in an inner position (on a radially inner side in this embodiment) and indicates the target vehicle speed range for the more distant traffic signal in an outer position (on a radially outer side in this embodiment) and thereby allows the driver to easily understand a relative positional relationship between the target vehicle speed range and the other target vehicle speed range. This allows clear indications of the plurality of target vehicle speed ranges to the driver.

[0062] Further, the driving support device 19 of this embodiment calculates the two target vehicle speed ranges for the two traffic signal points as the objects. However, the numbers of the traffic signal points and the object traffic signal points for which the target vehicle speed ranges are calculated may be arbitrarily set as long as the number is two or more.

[0063] In FIG. 5, the driving support device 19 indicates the marker 62 indicating the first target vehicle speed range and the marker 64 indicating the second target vehicle speed range in the speed indication area 48a. However, methods for indicating the first and second target vehicle speed ranges in the speed indication area are not limited to this.

[0064] Next, another example of the indications of the target vehicle speed ranges will be described with reference to FIG. 7. FIG. 7 is a schematic diagram illustrating an example of the speed indication area of the display device. A speed indication area 48c shown in FIG. 7 is an example of indication where the first target vehicle speed range is 15 km/h to 40 km/h and the second target vehicle speed range is 30 km/h to 50 km/h. The speed indication area 48c indicates a marker 70 in the speed range on the scale display section 50 which overlaps with the target vehicle speed. The marker 70 indicates the first target vehicle speed range. Further, the marker 70 has a first area 72 and a second area 74. The first area 72 corresponds to the range of lower than 30 km/h in the indication range of the marker 70. The second area 74 corresponds to the range of not lower than 30 km/h in the indication range of the marker 70. In other words, in the marker 70, the range (the range corresponding to only the first target vehicle speed range) which does not overlap with the second target vehicle speed range corresponds to the first area 72, and the range (the range where the first and second target vehicle speed ranges overlap with each other) which overlaps with the second target vehicle speed range corresponds to the second area 74. Further, the first area 72 differs from the second area 74 in at least the color or the pattern of indication. Further, the marker 70 is indicated such that the first and second areas preferably differ in size or the second area 74 is preferably larger than the first area 72.

[0065] As the speed indication area 48c, the driving support device 19 may indicate only a range of the calculated second target vehicle speed range which overlaps with the first target vehicle speed range. As described above, only the range of the second target vehicle speed range which overlaps with the first target vehicle speed range is indicated, and the driver can thereby understand that steady state driving in which speed range allows passage of the two traffic signal points without stopping, in other words, allows passage within a passing allowed period. Further, the target vehicle speed range for the more distant traffic signal point in the traveling direction is indicated in the target vehicle speed range for the closer traffic signal point, and the relative positional relationship between the target vehicle speed range and the other target vehicle speed range can be clearly indicated.

[0066] Further, in the example shown in FIG. 7, an upper limit of the first target vehicle speed range is the same speed as an upper limit of the second target vehicle speed range (in the reference speed range for calculation, the upper limit of the second target vehicle speed range is higher), and a lower limit of the first target vehicle speed range is lower than a lower limit of the second vehicle speed range. However, the driving support device 19 can perform the same process when the first and the second target vehicle speed ranges are in a different relationship, uses different indications for portions where the first and second target vehicle speed ranges do not overlap with each other, and can thereby clearly indicate the relative positional relationship between the target vehicle speed range and the other target vehicle speed range to the driver. Moreover, in a case that the entire first target vehicle speed range overlaps with the second target vehicle speed range, the driving support device 19 can adjust the color or size of the indications such that the driver can understand the overlapping and can thereby clearly indicate the relative positional relationship between the target vehicle speed range and the other vehicle speed range to the driver.

[0067] Further, the driving support device 19 indicates the second target vehicle speed range such that it overlaps with the marker 70 in the speed indication range 48c. However, a marker of a speed range corresponding to the second area may be indicated separately from the marker 70. Moreover, the driving support device 19 may modify the reference target vehicle speed range on the basis of the first target vehicle speed range when the second target vehicle speed range is calculated and may set only the portion of the reference target vehicle speed range which overlaps with the first target vehicle speed range as the second target vehicle speed range.

[0068] Next, another example of the process of the driving support device will be described with reference to FIGs. 8 to 10. Here, FIG. 8 is a flowchart illustrating another example of the process of the driving support device. FIGs. 9 and 10 are each a schematic diagram illustrating an example of the speed indication area of the display device. The process shown in FIG. 8 is executed instead of step SI 8 of FIG. 4 which is described above. In other words, the process shown in FIG. 8 is executed if the determination is Yes in step S 16 shown in FIG. 4, after this process is terminated, the process progresses to step S22.

[0069] The target vehicle speed control^" section 20c of the ECU 20 conducts a passage or stop determination for the traffic signal to be next passed in^" step S30. In other words, in step S30, the target vehicle speed control section 20c calculates the reference target vehicle speed range on the basis of the obtained information about the traffic signal (traffic signal point) to be next passed and determines whether performing a passage support (whether passage is possible) or a stop support according to the calculated reference target vehicle speed range. Further, the target vehicle speed control section 20c of this embodiment determines that it performs the stop support if the lower limit of the calculated reference target vehicle speed range is a speed a higher than the present vehicle speed, in other words, (the present vehicle speed + a) < (the lower limit speed of the reference target vehicle speed range).

[0070] The target vehicle speed control section 20c makes a determination in step S30. Thereafter, in step S32, the target vehicle speed control section 20c determines whether or not passage is possible, in other words, the determination result in step S32 is that the passage support is possible. If the target vehicle speed control section 20c determines that passage is not possible (No) in step S32, the process progresses to step S42.

[0071] Further, if the target vehicle speed control section 20c determines that passage is possible (Yes) in step S32, in other words, the passage support is possible, the target vehicle speed control section 20c conducts the passage or stop determination for the traffic signal to be second passed in step S34. In other words, in step S34, the target vehicle speed control section 20c calculates the reference target vehicle speed range on the basis of the obtained information about the traffic signal (traffic signal point) to be second passed and determines whether performing the passage support (whether passage is possible) or the stop support according to the calculated reference target vehicle speed range. The same reference for determination as step S30 can be used for step S34.

[0072] The target vehicle speed control section 20c makes a determination in step S34. Thereafter, in step S36, the target vehicle speed control section 20c determines whether or not passage is possible, in other words, the determination result in step S36 is that the passage support is possible. Further, if the target vehicle speed control section 20c determines that passage is possible (Yes) in step S36, in other words, the passage support is possible, the target vehicle speed control section 20c indicates the target vehicle speed ranges for the two traffic signals in step S38. That is, the indications same as step SI 8 described above are performed. Here, if a part of the reference target vehicle speed ranges calculated is higher than the. present vehicle speed + a, the target vehicle speed control section 20c of this embodiment sets the upper limit value of the target vehicle speed ranges to the present vehicle speed + a and indicates no speed higher than the present vehicle speed + a. The target vehicle speed control section 20c performs a process shown in step S38 and thereafter terminates the process.

[0073] Further, if the target vehicle speed control section 20c determines that passage is possible (No) in step S36, in other words, the passage support is not possible (No), the target vehicle speed control section 20c performs the indication of the target vehicle speed range for the traffic signal to be next passed and a stop support indication for the traffic signal to be second passed in step S40. The target vehicle speed control section 20c indicates an image which recommends deceleration in the speed indication area as the stop support indication in step S40. If the stop support indication is executed in step S40, the target vehicle speed control section 20c determines the second target vehicle speed range to be indicated on the basis of the first target vehicle speed range. The target vehicle speed control section 20c of this embodiment sets the lower limit of the second target vehicle speed range as the lower limit of the first target vehicle speed range and sets the upper limit of the second target vehicle speed range to the value such that the upper limit of the first target vehicle speed range is reduced by a certain ratio.

[0074] For example, the target vehicle speed control section 20c displays a speed indication area 48d shown in FIG. 9. The speed indication area 48d shown in FIG. 9 indicates a marker 80 in the speed range on the scale display section 50 which overlaps with the target vehicle speed range. The marker 80 indicates the first target vehicle speed range. Further, the marker 80 has a first area 83 and a second area 84. The first area 83 corresponds to the range of not lower than 30 km/h in the indication range of the marker 80. The second area 84 corresponds to the range of lower than 30 km/h in the indication range of the marker 80. In other words, in the marker 80, the range (the range corresponding to only the, first target vehicle speed range) which does not overlap with the second target vehicle speed range corresponds to the first area 83, and the range (the range where the first and second target vehicle speed ranges overlap with each other) which overlaps with the second target vehicle speed range corresponds to the second area 84. The target vehicle speed control section 20c performs a process shown in step S40 and thereafter terminates the process.

[0075] Further, if the target vehicle speed control section 20c determines that passage is not possible in step S32, the target vehicle speed control section 20c executes the stop support indication in step S42. Here, in the stop support indication in step S42, a speed range around zero km/h is indicated as the target vehicle speed range. For example, the target vehicle speed control section 20c displays a speed indication area 48e shown in FIG. 10. The speed indication area 48e indicates a marker 90 in the speed range on the scale display section 50 which overlaps with the target vehicle speed. The marker 90 is indicated in a speed range around zero km/h on the scale display section 50 of the speed indication section 48e. As described above, the target vehicle speed control section 20c indicates the determined target vehicle speed range as the marker 90 such that it overlaps with the scale display section 50. This allows the driver to notice that the target vehicle speed range is a speed range (a speed range including zero km/h, zero km/h to 10 km/h in this embodiment) around zero km/h only watching the speed indication area 48e and to notice that the vehicle 10 is to be stopped. The target vehicle speed control section 20c performs a process shown in step S42 and thereafter terminates the process.

[0076] As described above, the driving support device 19 of this embodiment determines whether the passage support is possible for each of the traffic signal points. Specifically, the target vehicle speed control section 20c determines whether or not the calculated reference target vehicle speed range exceeds the upper limit value set on the basis of the present vehicle speed. If the calculated reference target vehicle speed control section exceeds the upper limit set on the basis of the present vehicle speed, the stop support indication is executed. Accordingly, the reference target vehicle speed range where rapid acceleration is required for passing the object intersection or pedestrian crossing can be prevented from being indicated as the target vehicle speed range. This allows indication of the target vehicle speed range with less possibility of causing the driver to experience awkwardness or stress. Further, since this allows the driver to travel in the target vehicle speed range by acceleration and deceleration to an appropriate extent, the driver can sustain a comfortable driving state and can allow the vehicle to travel in preferable conditions (in this embodiment, while reducing stops at the red lights).

[0077] If it is determined that the stop support indication is performed for the closer traffic signal (the traffic signal to be next passed in this embodiment) in the traveling direction, the driving support device 19 of this embodiment does not determine the target vehicle speed range for the more distant traffic signal than the concerned traffic signal or indicate the target vehicle speed range for the more distant traffic signal either, thereby allowing indication of the target vehicle speed range which the driver can easily understand.

[0078] If it -is determined that the stop support indication for the more distant traffic signal is performed, the driving support device 19 of this embodiment indicates that it is recommended that the vehicle travel at a lower vehicle speed in the target vehicle speed range for the closer traffic signal as the stop support indication, thereby allowing reduction in the possibility that the user conducts unnecessary acceleration. As long as the stop support indication performed by the driving support device 19 if the stop support indication for the more distant traffic signal in the traveling direction is performed is an indication recommending that the driver stop the vehicle, various indications are possible.

[0079] Further, if the calculated reference target vehicle speed range exceeds the upper limit value set on the basis of the present vehicle speed, the driving support device 19 performs the stop support indication. Accordingly, the target vehicle speed range which is not higher than the upper limit value set on the basis of the present vehicle speed is indicated in the speed indication area 48. In other words, the driving support device 19 can prevent the indication of the speed higher than the upper limit value (indication upper limit speed) set on the basis of the present vehicle speed detected by the vehicle speed sensor 40 as the target vehicle speed range to be indicated in the speed indication area 48. Accordingly, the driving support device 19 can prevent the indication of the target vehicle speed range that requires rapid acceleration and thereby allows the indication of the target vehicle speed range with less possibility of causing the driver to experience awkwardness or stress. Further, since this allows the driver to travel in the target vehicle speed range by acceleration and deceleration to an appropriate extent, the driver can sustain a comfortable driving state and can allow the vehicle to travel in preferable conditions (in this embodiment, while reducing stops at the red lights).

[0080] Further, the driving support device 19 sets the present vehicle speed + a, in other words, a speed which is a certain magnitude higher than the present vehicle speed as the reference speed for the determination whether the passage support is possible, thereby allowing prevention of the acceleration required for gaining the target vehicle speed range from becoming large. This allows the vehicle 10 and the driving support device 19 to indicate the target vehicle speed range with further less possibility of causing the driver to experience awkwardness or stress.

[0081] Further, if the passage support is not possible, specifically, if the reference target vehicle speed range is higher than the indication upper limit speed, the driving support device 19 indicates the target vehicle speed range for the stop support, thereby recommending that the driver should stop the vehicle. This allows the driving support device 19 to prevent recommendation of difficult acceleration to the driver but to provide recommendation of stopping to the driver, thereby allowing reduction in the possibility of causing the driver to experience awkwardness or stress.

[0082] In this embodiment, if the passage support is not possible, specifically, if the reference target vehicle speed range is higher than the indication upper limit speed or the traffic signal is not the green light, the target vehicle speed range for the stop support is indicated. However, the present invention is not limited to this. If the passage support is not possible or the traffic signal is not the green light, the driving support device 19 may prevent indication of the target vehicle speed instead of the process of step S42.

[0083] The driving support device 19 of this embodiment sets the indication upper limit speed (the reference speed for the determination whether the passage support is possible) to the present vehicle speed + a, in other words, to the speed a certain magnitude higher than the present vehicle speed. However, the present invention is not limited to this. Here, the driving support device 19 may set the indication upper limit speed to the present vehicle speed + G x t. Here, "G" denotes acceleration, and "t" denotes time. In other words, the driving support device 19 may set the reference speed for the determination whether the passage support is possible to the present speed + G x t, in other words, the speed which can be achieved by acceleration G in t second(s). Here, the t second(s) may be a value which changes on the basis of the distance to the traffic signal and the present vehicle speed. For example, when the distance to the traffic signal is long, t may be made large. When the distance to the traffic signal is short, t may be made small.

[0084] Further, the driving support device 19 of this embodiment may set the indication upper limit speed to the present vehicle speed. As described above, the target vehicle speed control section 20c the reference speed for the determination whether the passage support is possible to the present vehicle speed and can thereby set the target vehicle speed range as a speed which requires no acceleration. Accordingly, the driving support device 19 can prevent the indication of the target vehicle speed range which requires acceleration and thereby allows the indication of the target vehicle speed range with less possibility of causing the driver to experience awkwardness or stress.

[0085] Further, each example of the driving support device 19 of the embodiment described above uses the present vehicle speed to determine the indication upper limit speed. However, the present invention is not limited to this. The driving support device 19 may use the speed limit of the road (way) on which the vehicle is traveling. Here, the speed limit is, for example, the legal speed limit of the road on which the vehicle is traveling at present and may be obtained from the infrastructure information obtained by the infrastructure communication section 38 or may be obtained from the information about the present position stored in the map information database 22a by detecting the present position by use of the GPS signals received by the GPS communication section 32. The driving support device 19 may use a combination of the infrastructure communication section 38, the GPS communication section 32, and the map information database 22a as an information obtainment section for obtaining the information about the speed limit. The information obtainment section for obtaining the information about the speed limit may use other functions of the driving support device 19, for example, the onboard camera 34. The driving support device 19 uses the onboard camera 34 to obtain images of traffic signs provided on the road on which the vehicle is traveling and may thereby detect the legal speed limit displayed in the image of the traffic sign as the speed limit. The driving support device 19 uses the speed limit as the reference speed for the determination whether the passage support is possible and can thereby prevent the indication of the target vehicle speed range from exceeding the speed limit. Accordingly, the driving support device 19 can indicate the target vehicle speed range as a speed of the speed limit or lower, can thereby prevent the indication of the speeds at which the vehicles must not travel, and thereby allows the indication of the target vehicle speed range with less possibility of causing the driver to experience awkwardness or stress.

[0086] The driving support device 19 preferably uses both the present vehicle speed and the speed limit to determine the indication upper limit speed (the reference speed for the determination whether the passage support is possible). In other words, in each case, the driving support device 19 preferably use the present vehicle speed to determine the indication upper limit speed so that the target vehicle speed range does not exceed the speed limit. Accordingly, the driving support device 19 can provide both the effects described above and thereby allows the indication of the target vehicle speed range with further less possibility of causing the driver to experience awkwardness or stress.

[0087] Further, an example is described where the driving support device 19 of the embodiment described above sets the indication upper limit speed as the reference speed for the determination whether the passage support is possible and one of various conditions. However, the reference speed for the determination whether the passage support is possible may be set separately from the indication upper limit speed. In other words, the driving support device 19 may determine whether it executes the passage support according to the reference speed for the determination whether the passage support is possible and may determine the upper limit value to be indicated as the target vehicle speed range on the basis of an indication upper limit speed other than the reference speed for the determination whether the passage support is possible. Further, similarly to the reference speed for the determination whether the passage support is possible, the various conditions described above can be used for the indication upper limit speed. In such a case, the driving support device 19 adjusts the reference target vehicle speed range on the basis of the indication upper limit speed and determines the target vehicle speed range.

[0088] The driving support device 19 preferably provides the indicated markers having different colors according to the target vehicle speed range which is indicated in the passage support or the target vehicle speed range which is indicated in the stop support. The indication may have different patterns, illumination states, or the like instead of colors. This allows the driver to understand that the indication is to notify the passage support or the stop support.

[0089] Next, another example of the process of the driving support system will be described with reference to FIGs. 11 and 12. Here, FIG. 11 is a flowchart illustrating another example of the process of the driving support device. FIG. 12 is a schematic diagram illustrating an example of the speed indication area of the display device. The process _ssteps shown in FIG. 11 which are the same as the. steps shown in FIG. 8 will be denoted by like step numerals and specific descriptions will be omitted.

[0090] The target vehicle speed control section 20c of the ECU 20 conducts the passage or stop determination for the traffic signal to be next passed in step S30. The target vehicle speed control section 20c makes a determination in step S30. Thereafter, in step S32, the target vehicle speed control section 20c determines whether or not passage is possible, in other words, the determination result in step S32 is that the passage support is possible. If the target vehicle speed control section 20c determines that passage is not possible (No) in step S32, the process progresses to step S42.

[0091] Further, if the target vehicle speed control section 20c determines that passage is not possible in step S32, the target vehicle speed control section 20c executes the stop support indication in step S42. The target vehicle speed control section 20c performs the process shown in step S42 and thereafter terminates the process.

[0092] Further, if the target vehicle speed control section 20c determines that passage is possible (Yes) in step S32, in other words, the passage support is possible, the target vehicle speed control section 20c conducts the passage or stop determination for the traffic signal to be second passed in step S34. The target vehicle speed control section 20c makes a determination in step S34. Thereafter, in step S36, the target vehicle speed control section 20c determines whether or not passage is possible, in other words, the determination result in step S36 is that the passage support is possible. Further, if the target vehicle speed control section 20c determines that passage is possible (Yes) in step S36, in other words, the passage support is possible, the target vehicle speed control section 20c determines whether (Vmin2) > (Vmax + K) in step S50. Here, Vmin2 is the lower limit value of the target vehicle speed range calculated for the traffic signal to be second passed. Vmax is the upper limit value of the target vehicle speed range calculated for the traffic signal to be next passed. Further, K is a set threshold value, in other words, in step S50, the target vehicle speed control section 20c determines whether the lower limit value of the target vehicle speed range calculated for the traffic signal to be second passed is the threshold value K higher than the upper limit value of the target vehicle speed range calculated for the traffic signal to be next passed.

[0093] If the target vehicle speed control section 20c determines that (Vmin2) > (Vmax + K) (Yes), the target vehicle speed control section 20c indicates the target vehicle speed range for only the traffic signal to be next passed in step S52. In other words, the target vehicle speed control section 20c executes a process the same as step S20 described above. The target vehicle speed control section 20c performs the process shown in step S52 and thereafter terminates the process.

[0094] If the target vehicle speed control section 20c determines that (Vmin2) > (Vmax + K) is false (No), the target vehicle speed control section 20c indicates the target vehicle speed range for the traffic signal to be second passed in step S38. That is, the indications same as step S 18 described above are performed. The target vehicle speed control section 20c performs the process shown in step S38 and thereafter terminates the process.

[0095] Further, if the target vehicle speed control section 20c determines that passage is possible (No) in step S36, in other words, the passage support is not possible (No), the target vehicle speed control section 20c performs the indication of the target vehicle speed range for the traffic signal to be next passed and the stop support indication for the traffic signal to be second passed in step S40. As the stop support indication in step S40, the target vehicle speed control section 20c indicates the second target vehicle speed range as the same as the speed range indicated in the case that the stop support indication is performed for the traffic signal to be next passed.

[0096] For example, the target vehicle speed control section 20c displays a speed indication area 48f shown in FIG. 12. The speed indication area 48f indicates markers 96 and 98 in the speed range on the scale display section 50 which overlaps with the target vehicle speed ranges. The marker 96 indicates the first target vehicle speed range, and the marker 98 indicates the second target vehicle speed range. Here, in the speed indication area 48f shown in FIG. 12, the marker 96 is indicated in the speed range of 20 km/h to 40 km/h on the scale display section 50. The marker 98 is indicated in the speed range of zero km/h to 10 km/h on the scale display section 50. Further, in the speed indication area 48f, the marker 96 is disposed on an inner peripheral side than the marker 98. As described above, the target vehicle speed control section 20c indicates the second target vehicle speed range for the stop support indication as the marker 98 such that it overlaps with the scale display section 50. This allows the driver to notice that the second target vehicle speed range is a speed range around zero km/h only watching the speed indication area 48f and to notice that stopping the vehicle 10 before the second traffic signal is recommended, in other words, that the second traffic signal turns to the red light and the vehicle temporarily stops. The target vehicle speed control section 20c performs the process shown in step S40 and thereafter terminates the process.

[0097] As shown in step S50, the driving support device 19 determines whether the lower limit value of the target vehicle speed range calculated for the traffic signal to be second passed is the threshold value K higher than the upper limit value of the target vehicle speed range calculated for the traffic signal to be next passed. If the above relationship is satisfied, the driving support device 19 prevents indication of the target vehicle speed range for the second traffic signal to be passed, thereby allowing reduction in the possibility that the target vehicle speed range causes the driver to experience awkwardness. Further, after passing the next traffic signal, the driving support device 19 prevents indication of the second target vehicle speed range where acceleration which is more intensive than a prescribed magnitude, thereby allowing reduction in the possibility of causing the driver to experience uneasiness.

[0098] Further, when the traveling route is set by the automotive navigation system 28, the driving support device 19 calculates the traveling direction and a route to pass on the basis of the traveling route set by the automotive navigation system 28 and preferably executes the processes of steps S I 8 and S30 on the basis of whether or not the traffic signal on the route to pass indicates that the passage in the traveling direction is allowed. As described above, the direction to proceed is specified on the basis of the traveling route, thereby make it possible to indicate of the target vehicle speed range appropriate for the indication state of the traffic signal.

[0099] Further, the target vehicle speed control section 20c of the driving support device 19 may use at least one of the onboard camera 34 and the millimeter- wave radar 36 to determine whether or not a vehicle is present within a certain distance ahead. If it is determined that a vehicle is present within the certain distance ahead, the target vehicle speed control section 20c may prevent execution of the stop support or indication of the target vehicle speed range. Accordingly, the possibility can be reduced that since the target vehicle speed range for passage the obj ct intersection or pedestrian crossing in a state where a vehicle is present within the certain distance ahead, the driver is caused to rush.

[0100] Further, in the case that ( upper limit value Vmax) - ( lower limit value Vmin) < ( threshold value), in other words, the speed difference between the upper limit value and the lower limit value of the determined target vehicle speed range is smaller than the threshold value, the driving support device 19 may prevent indication of the target vehicle speed range. For example, after determining the target vehicle speed range in step SI 8, the target vehicle speed control section 20c determines whether ( upper limit value Vmax) - ( lower limit value Vmin > ( threshold value), in other words, the difference between the upper limit value Vmax and the lower limit value Vmin of the target vehicle speed range is larger than the threshold value. If it is determined that ( upper limit value Vmax) - ( lower limit value Vmin) > ( threshold value), the target vehicle speed control section 20c indicates the deteraiined target vehicle speed range in the speed indication area. If the determination is that ( upper limit value Vmax) - ( lower limit value Vmin) > ( threshold value) is false, in other words, if it is determined that ( upper limit value Vmax) - ( lower limit value Vmin) < ( threshold value), the target vehicle speed control section 20c prevent indication of the determined target vehicle speed range.

[0101] Further, in the case that ( upper limit value Vmax) - ( lower limit value Vmin) < ( threshold value), in other words, the speed difference between the upper limit value and the lower limit value of the determined target vehicle speed range is smaller than the threshold value, the driving support device 19 prevent indication of the target vehicle speed range and thereby prevent indication of the target vehicle speed range which permits a narrow speed range and results in difficult conditions for speed adjustment. Accordingly, the driving support device 19 can selectively indicates the target vehicle speed range which permits a wide speed range and results in relatively easy condition for speed adjustment and thereby allows the indication of the target vehicle speed range with less possibility of causing the driver to experience awkwardness or stress.

[0102] Further, the driving support device 19 of the embodiment described above provides the speed indication in the speed indication area 48 of the display device 42 by the analog meter. However, the present invention is not limited to this. Further, the driving support device 19 of the embodiment described above may provide the speed indication in the speed indication area 48 of the display device 42 by a digital meter. Here, FIG. 13 is a schematic diagram illustrating another example of the speed indication area of the display device. A speed indication area 102 is an indication mechanism which indicates speeds in numbers and has a first area 104, a second area 106, and a third area 108. The present vehicle speed is indicated in the first area 104. The first area 104 of FIG. 13 indicates "40 km/h". The second area 106 is an area above the first area 104 on a screen. The first target vehicle speed range is indicated in the second area 106. The second area 106 of FIG. 13 indicates "30 km/h ~ 53 km/h". The third area 108 is an area below the first area 104 on the screen. The second target vehicle speed range is indicated in the third area 108. The third area 108 of FIG. 13 indicates "45 km/h ~ 62 km/h". As described above, the driving support device 19 can obtain a similar effect to the above example by indicating the speed indication area 102 of the display device 42 by the digital meter. Further, the driving support device 19 has the second area 106 disposed above the first area 104 and has the third area 108 fixed below the first area 104. This allows the driver to more easily recognize the first target vehicle speed range for the traffic signal to be next passed and the second target vehicle speed range for the traffic signal to be second passed. Here, the driving support device 19 preferably indicates the present vehicle speed indicated in the first area 104 of the speed indication area 102, the first target vehicle speed range indicated in the second area 106, and the second target vehicle speed range indicated in the third area 108 in at least either different colors or different sizes. Accordingly, the driving support device 19 can reduce the possibility that the driver confuses the present vehicle speed with the target vehicle speed ranges.

[0103] Next, with reference to FIG. 14, timings at which the driving support device 19 executes the process of calculating and indicating the target vehicle speed ranges described above. FIG. 14 is an explanatory view illustrating an example of the process of the driving support device. The driving support device 19 may set various timings for executing the process of calculating and indicating the target vehicle speed ranges described above. For example, the driving support device 19 may execute the indication of the target vehicle speed range at a point 204 where the distance between the vehicle 10 in which the own device is installed and a traffic signal 12b (traffic signal point) to be next passed becomes a prescribed distance. In such a case, the driving support device 19 determines the relationship with a traffic signal 12c when the vehicle 10 passes the point 204 and determines whether the second target vehicle speed range for the traffic signal 12c is indicated. Further, after the indication is performed at the point 204, the driving support device 19 sustains the indication or may again execute the process of calculating and indicating the target speed range if the distance to the traffic signal more distant than the traffic signal 12b becomes the distance which satisfies the indication timing. Moreover, when the driving support device 19 starts the process of calculating and indicating the target vehicle speed range after passing the point 204, the driving support device 19 may constantly update the infrastructure information or the like and thereby update the indication of the target vehicle speed range. Even if the traffic signal 12c presently does not satisfy the conditions for the indication of the second target vehicle speed range, the driving support device 19 updates the indication of the target vehicle speed range, can thereby obtain the information about the traffic signal cycles, and can indicate the second target vehicle speed range when the distance falls in the threshold value.

[0104] Further, the driving support device 19 of the embodiment described above determines each of the target vehicle speed ranges which is information about a speed range having the upper and lower limit speeds different from each other on the basis of the reference target vehicle speed range and can thereby indicate information which facilitates understanding of the driver and driving corresponding to the target vehicle speed range. Here, the driving support device 19 can use information other than the target vehicle speed range as target vehicle speed information which is calculated on the basis of the reference target vehicle speed range. For example, a speed as a single value, which is not a range, may be used as the, target vehicle speed information.

[0105] Further, the driving support device 19 of the embodiment described above includes the vehicle interval control section 20a and the vehicle maintenance control section 20b. However, the driving support device 19 does not necessarily have to include the vehicle interval control section 20a and the vehicle maintenance control section 20b. Further, the vehicle 10 and the driving support device 19 may be differently configured as long as the control by the vehicle speed control section 20c described above can be achieved.

[0106] While the disclosure has been explained in conjunction with specific exemplary embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, exemplary embodiments of the disclosure as set forth herein are intended to be illustrative, not limiting. There are changes that may be made without departing from the scope of the disclosure.

Claims

1. A driving support device for supporting driving of a vehicle, the device comprising: an infrastructure communication section that obtains signal cycle information concerning switching among indications of the respective traffic signals which are disposed at two or more points in a traveling direction of the vehicle;

a position calculation section that calculates relative position information which represents relative positions between a present position of the vehicle and each of the plurality of points; - a target vehicle speed control section that calculates, as reference target vehicle speed ranges, respective speed ranges in which the vehicle can pass the respective points while the traffic signals are in a passage allowed indication state where the traffic signal indicates that passage of the vehicle is allowed, based on the relative position information and the signal cycle information and that determines respective target vehicle speed information based on the reference target vehicle speed ranges; and

a target vehicle speed display section that displays the target vehicle speed information about the plurality of points which is determined by the target vehicle speed control section.

2. The driving support device according to claim 1 ,

wherein the signal cycle information is cycles in which indications of the traffic signals are switched or timings in which the indications of the traffic signals change.

3. The driving support device according to claim 1 or 2,

wherein the target vehicle speed control section prevents an indication of the target vehicle speed information about a second point on the target vehicle speed display section if a difference between the target vehicle speed information about a first point that is the point which is closer to vehicle in the traveling direction and the target vehicle speed information about the second point that is the point which is more distant than the first point in the traveling direction exceeds a preset threshold.

4. The driving support device according to claim 3,

wherein the difference between the target vehicle speed information about the first point and the target vehicle speed information about the second point is a difference between an upper limit value of the target vehicle speed information about the first point and a lower limit value of the target vehicle speed information about the second point.

5. The driving support device according to any one of claims 1 to 4,

wherein the target vehicle speed control section prevents the indication of the target vehicle speed information about the second point on the target vehicle speed display section if a distance between the first point which is closer to the vehicle in the traveling direction and the second point which is more distant than the first point in the traveling direction exceeds a preset threshold.

6. The driving support device according to any one of claims 1 to 4,

wherein the target vehicle speed control section prevents the indication of the target vehicle speed information about the second point if a distance between the vehicle and the second point exceeds a threshold value.

7. The driving support device according to any one of claims 1 to 6,

wherein the target vehicle speed control section determines whether or not the target vehicle speed information about the first point is indicated on the target vehicle speed display section based on a preset condition.

8. The driving support device according to any one of claims 1 to 7,

wherein the target vehicle speed control section prevents the indication of the target vehicle speed information about the second point on the target vehicle speed display section if the target vehicle speed control section determines to prevent an indication of the target vehicle speed information about the first point.

9. The driving support device according to any one of claims 1 to 8,

wherein the target vehicle speed control section prevents the indication of the target vehicle speed information about the second point on the target vehicle speed display section if the target vehicle speed control section determines that the vehicle cannot pass the first point while the traffic signal at the first point is in the passage allowed indication state based oh the reference target vehicle speed range for the first point.

10. The driving support device according to claim 9, further comprising

a vehicle speed sensor that detects the travel speed of the vehicle,

wherein the target vehicle speed control section sets an indication upper limit speed which is an upper limit value of a travel speed range which is the target vehicle speed information based on a present vehicle speed detected by the vehicle speed sensor, and the target vehicle speed control section determines that the vehicle cannot pass the point while the traffic signal is in the passage allowed indication state if an entire range of the reference target vehicle speed range exceeds the indication upper limit speed.

11. The driving support device according to claim 9, further comprising

an information obtainment section that obtains a speed limit of a road on which the vehicle is traveling,

wherein the target vehicle speed control section sets the speed limit as the indication upper limit speed and determines that the vehicle cannot pass the point while the traffic signal is in the passage allowed indication state if the entire range of the reference target vehicle speed range exceeds the indication upper limit speed.

12. The driving support device according to claim 10 or 11 ,

wherein the target vehicle speed control section sets the target vehicle speed information to speed information being equal to or lower than the indication upper limit speed.

13. The driving support device according to any one of claims 9 to 12,

wherein the target vehicle speed control section sets the target vehicle speed information about the point to speed information including zero km/h if the vehicle cannot pass the point.

14. The driving support device according to any one of claims 1 to 13,

wherein the target vehicle speed information is information about a speed range having upper limit and lower limit speeds differing from each other.

15. The driving support device according to any one of claims 1 to 14,

wherein the target vehicle speed control section indicates speeds of the target vehicle speed information about the second point which overlap with the target vehicle speed information about the first point on the target vehicle speed display section as the target vehicle speed information about the second point.

16. A driving support method for supporting driving of a vehicle, the method comprising: obtaining signal cycle information concerning switching among indications of the respective traffic signals which are disposed at two or more points in a traveling direction of the vehicle;

calculating relative position information which represents relative positions between a present position of the vehicle and each of the plurality of points;

calculating, as reference target vehicle speed ranges, respective speed ranges in which the vehicle can pass the respective points while the traffic signals are in a passage allowed indication state where the traffic signal indicates that passage of the vehicle is allowed, based on the relative position information and the signal cycle information; determining target vehicle speed information based on the reference target vehicle speed ranges; and displaying the target vehicle speed information about the plurality of points.