Abstract:
A driving state determining system in a vehicle recognizes an obstruction that may collide with the vehicle based on obtained various information. The system executes a plurality of danger determinations that have individual determination conditions, based on a relative distance and a relative speed with the obstruction to thereby comprehensively determine one of danger regions that the vehicle is situated in. The danger regions are classified depending on a danger degree. The system then outputs a determined result to relevant devices. Each of the relevant devices thereby determines operation by obtaining the comprehensively determined result outputted by the system. Consequently, the relevant devices can function more cooperatively and more effectively to lead to increase in safety than another system where each of relevant devices determines operation by individually collecting information.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based on and incorporates herein by reference Japanese Patent Application No. 2004-178581 filed on Jun. 16, 2004.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to a driving state determining system that determines driving states based on information from various in-vehicle sensors or the like to thereby output determination results.  
       BACKGROUND OF THE INVENTION  
       [0003]     A safety system called Pre-Crash Safety System starts to come into practical use. This system determines beforehand a subject vehicle&#39;s state where a collision is unavoidable to thereby promptly activate safety equipment for decreasing collision damage (refer to Patent Document 1). In detail, a detector such as a millimeter wave radar detects a position, a distance, a speed, or the like of an obstruction ahead of a subject vehicle. When it is determined that collision with this obstruction is unavoidable, a seatbelt for a driver&#39;s seat or a driver-assistance&#39;s seat is fastened just before the collision so that fixation of an occupant is secured. Further, stepping of a braking pedal is detected to cause an enforced braking force. Avoidance of the collision or protection of occupants at the collision can be thereby achieved.  
         [0004]     Patent Document 1: JP-2000-247211 A  
         [0005]     A conventional safety system such as the above works after a collision with an obstruction is determined to be unavoidable. Therefore, the system does not function for a purpose that a driver recognizes a danger beforehand to thereby conduct an operation for preventing the accident from occurring. A state where this safety system works is a last stage for collision avoidance or occupant protection. Activating this safety system may give an occupant discomfort or involve a rear-end collision with a following vehicle. It is therefore preferable that a driver conducts a proper operation before the above safety system is activated.  
         [0006]     Analysis of causes of recent traffic accidents indicates that head-on collisions at intersections and rear-end collisions in straight roads account for the first and second largest portions, respectively. The above-described safety system detects danger of collision when a millimeter wave radar mounted in the front of a vehicle detects an obstruction. Therefore, the system only responds to an obstruction (a preceding vehicle, an on-road obstruction, or an oncoming vehicle) ahead of the subject vehicle, which is limited to uses in straight roads. In sum, the system does not function against head-on collisions at intersections.  
       SUMMARY OF THE INVENTION  
       [0007]     It is an object of the present invention to provide a driving state determining system to solve the above problem. The system determines a present driving state as one of multiple danger states and causes a driver to recognize one of the danger states and thereby rapidly conduct operation for preventing the corresponding danger state.  
         [0008]     To achieve the above object, a driving state determining system in a vehicle is provided with the following. An obtaining unit is included for obtaining information including vehicle information of the vehicle and surrounding information for understanding a state surrounding the vehicle. A determining unit is included for recognizing an obstruction that has a possibility of colliding with the vehicle based on the information and for executing a plurality of danger determinations that have individual determination conditions, based on a relative distance between the vehicle and the obstruction and a relative speed between the vehicle and the obstruction. An outputting unit is further included for outputting to other devices a signal based on a result of a danger determination executed by the determining unit.  
         [0009]     Under this structure, a plurality of danger determinations (or region determinations) having individual determining conditions are executed with respect to an obstruction based on a relative distance and a relative speed between a subject vehicle and an obstruction. Accordingly, various driving states are determined. The driving states include, e.g., (i) a state where a driver needs to be warned, (ii) a state where an operation for avoiding or preventing danger needs to be started, and (iii) a state where an operation for anticipating or responding to a possible collision needs to be executed. Then a signal based on a determined result is sent to other relevant devices to thereby cause the relevant devices to properly conduct operation (notifying for drawing attention of a driver, assisting an operation for avoiding the danger, or protecting an occupant). Here, the driving states are determined by synthesizing various information; then signals for activating other devices or signals for determining whether other devices should start are comprehensively outputted. Therefore, this system is more effective and other devices more cooperatively work, than a system where each of other devices determines an operation by individually collecting information.  
         [0010]     As another aspect of the present invention, to achieve the above object, a driving state determining system in a vehicle is provided with the following. An obtaining unit is included for obtaining information including vehicle information of the vehicle and surrounding information for understanding a state surrounding the vehicle. A determining unit is included for recognizing a point where the vehicle needs to stop based on the information and for executing a plurality of danger determinations that have individual determination conditions, based on a distance between the vehicle and the point and a speed of the vehicle. An outputting unit is further included for outputting to other devices a signal based on a result of a danger determination executed by the determining unit.  
         [0011]     Under this structure, a plurality of danger determinations (or region determinations) having individual determining conditions are executed with respect to a temporary-stop-required position based on a distance to the temporary-stop-required position and a speed of a subject vehicle. Accordingly, various driving states are determined. The driving states include, e.g., (i) a state where a driver needs to be warned, (ii) a state where a stop operation needs to be started, and (iii) a state where an emergency stop needs to be operated. Then a signal based on a determined result is sent to other relevant devices to thereby cause the relevant devices to properly conduct operation (notifying for drawing attention of a driver, assisting an operation for stopping the subject vehicle, or executing an emergency stop). Here, the driving states are determined by synthesizing various information; then signals for activating other devices or signals for determining whether other devices should start are comprehensively outputted. Therefore, this system is more effective and other devices more cooperatively work, than a system where each of other devices determines an operation by individually collecting information.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:  
         [0013]      FIG. 1  is a block diagram of a navigation device and its peripheral devices;  
         [0014]      FIG. 2  is a flowchart diagram of a region determination process with respect to an obstruction;  
         [0015]      FIG. 3  is a flowchart diagram of a region determination process with respect to a temporary stop;  
         [0016]      FIG. 4  is a flowchart diagram of a process responding to an obstruction;  
         [0017]      FIG. 5  is a flowchart diagram of a process responding to a temporary stop; and  
         [0018]      FIGS. 6A, 6B  are views showing region images. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     A driving state determining system according to an embodiment of the present invention is adapted to a navigation device  11 .  FIG. 1  shows a block diagram of the navigation device  11  and its peripheral devices, all of which are mounted in a subject vehicle. The navigation device  11  connects with a speed sensor  19 , a position sensor  21 , a sound output device  23 , a display device  25 , and an in-vehicle LAN  41 .  
         [0020]     The speed sensor  19  is disposed in a hub of a wheel assembly or the like to detect a vehicle speed and output a detection result to the navigation device  11 . The position sensor  21  includes a GPS (Global Positioning System) antenna, and a gyroscope to output to the navigation device  11  information necessary for computing a present position or information enabling understanding of driving states of the subject vehicle. The sound output device  23  includes a speaker and an amplifier to output sounds based on signals from the navigation device  11 . The display device  25  includes a liquid crystal display or an organic electro luminescent display to output images based on signals from the navigation device  11 .  
         [0021]     The navigation device  11  includes a determining unit  13 , an interfacing unit  15 , and storing unit  17 . The determining unit  13  includes a CPU, a ROM, a RAM, and a bus connecting the foregoing components (non shown). The CPU of the determining unit  13  executes a given program to thereby achieve various functions such as a route guiding function. The interfacing unit  15  includes a communications-purpose microcomputer (not shown) to communicate with sensors or the like directly connected with the navigation device  11  or the devices connected via the in-vehicle LAN  41  with the navigation device  11 . The storing unit  17  includes a storage medium such as a hard disk, a DVD-ROM, or a memory card, and an access unit that accesses to the storage medium. The storage medium stores map data, sound data, various programs, or the like. The in-vehicle LAN  41  connects with at least a pre-crash safety control device  29 , a steering control device  31 , a throttle control device  33 , a brake control device  35 , a seat control device  37 , and a seatbelt control device  39 .  
         [0022]     The pre-crash safety control device  29  determines beforehand a subject vehicle&#39;s driving state that a collision is unavoidable and then promptly activates safety equipment to thereby decrease damage due to the collision. The pre-crash safety control device  29  includes a CPU, a ROM, a RAM, and a bus connecting the foregoing components (non shown). The CPU of the pre-crash safety control device  29  executes a program to thereby achieve the above function. The pre-crash safety control device  29  connects with a forward radar  27  that is mounted in the front portion of the subject vehicle to output millimeter waves for detecting obstructions. The pre-crash safety control device  29  thereby receives detection results from the forward radar  27  and outputs the detection results to the in-vehicle LAN  41 .  
         [0023]     The steering control device  31  controls a function of assisting a driver to steer the vehicle and a function of causing a driver to recognize abnormality by vibrating a steering wheel. The steering control device  31  further detects steering states (or steering angles).  
         [0024]     The throttle control device  33  controls an engine throttle and detects throttle states (or opening degrees).  
         [0025]     The brake control device  35  controls a brake booster or a brake actuator to mainly adjust a relationship between a driver&#39;s stepping force and a braking force. The brake control device  35  causes the brake booster or the like to increase a braking force more than usual in an emergency; further, the brake control device  35  forcibly causes the brake booster or the like to increase a braking force in a state that a collision is unavoidable.  
         [0026]     The seat control device  37  controls an electromotive motor for power seats or the like and further controls a function of causing a driver to recognize abnormality by vibrating a seat.  
         [0027]     The seatbelt control device  39  controls a motor fastening a seatbelt.  
         [0028]     Next, various process executed by the determining unit  13  or the pre-crash safety control device  29  will be explained below. The determining unit  13  executes (1) region determining process for an obstruction and (2) region determining process for a temporary stop. The pre-crash safety control device  29  executes (3) obstruction-responding process and (4) temporary stop-responding process. Usual process by a navigation device such as a route guiding process is not explained here.  
         [0029]     (1) Region Determining Process for Obstruction (Refer to  FIG. 2 )  
         [0030]     The determining unit  13  starts this process when an ignition of the subject vehicle is turned on. Firstly, at Step S 110 , a vehicle speed is computed based on signals inputted from the speed sensor  19 . At Step S 115 , a position of the subject vehicle is computed based on information inputted from the position sensor  21 . At Step S 120 , information of a forward obstruction ahead of the subject vehicle is obtained from the pre-crash safety control device  29  via the in-vehicle LAN  41 . This information includes a relative distance or a relative speed with the obstruction (or vehicle). Here, an obstruction includes any one interfering with traveling of a vehicle such as a fallen object, a traffic sign, a guardrail, or a vehicle (parked vehicle, traveling vehicle).  
         [0031]     At Step S 123 , it is determined whether an obstruction that has a possibility of colliding with the subject vehicle is present based on the information obtained at the preceding process at Steps S 110 , S 115 , and S 120 . When an obstruction that has a possibility of colliding with the subject vehicle is determined to be present, the sequence goes to S 125 . When an obstruction that has a possibility of colliding with the subject vehicle is determined not to be present, the sequence returns to S 110 .  
         [0032]     At Step S 125 , given information is obtained via the in-vehicle LAN  41 . This given information includes (i) information of how the driver operates the steering, from the steering control device  31 , (ii) information of how the driver operates the throttle, from the throttle control device  33 , (iii) information of how the driver operates the brake, from the brake control device  35 .  
         [0033]     At Step S 130 , it is determined whether the driver intends to avoid an obstruction having a possibility of colliding with the subject vehicle based on the information computed or obtained at Steps S 110 , S 115 , S 120 , and S 125 . This determination can be executed by various methods as follows. When the driver operates to avoid a traveling course to lead to collision with an obstruction or operates to decrease the speed as approaching the obstruction, it is determined that the driver has an intention of avoidance. When the driver does not conduct such the operation, it is determined that the driver has no intention of avoidance.  
         [0034]     At Step S 135 , the sequence is branched depending on the determination result at Step S 130 . When the driver has an intension of avoiding an obstruction, the sequence returns to S 110 . When the driver has no intension of avoiding an obstruction, the sequence goes to S 140 .  
         [0035]     At Step S 140 , it is determined whether the subject vehicle enters a warning region, which will be explained with reference to  FIG. 6A  as follows. This warning region is, for instance, within  50  meters short of an avoidance-required position in an approaching direction with respect to an obstruction (a parked vehicle in  FIG. 6A ). The avoidance-required position is a position from which the driver needs to start an operation for avoiding an obstruction. Within the warning region before reaching this avoidance-required position, the vehicle or the driver is in a state where the driver needs to at least recognize the presence of the obstruction. This warning region varies depending on a vehicle speed. When the subject vehicle enters the warning region, the sequence goes to Step S 145 . When the subject vehicle does not enter the warning region, the sequence returns to Step S 110 .  
         [0036]     At Step S 145 , the sound output device  23  is sent a signal and caused to output a sound that causes the driver to recognize the presence of the obstruction or that draws attention of the driver. For instance, the sound is “An obstruction regarded as a parked vehicle is present  100  meters ahead. Please operate for avoidance.” The display device  25  is also sent the signal and caused to display an image indicating positions of the subject vehicle and the obstruction on a map.  
         [0037]     At Step S 150 , it is determined whether the subject vehicle enters a danger avoidable region, which will be explained with reference to  FIG. 6A  as follows. This danger avoidable region is, for instance, in the approaching direction with respect to the obstruction, from the avoidance-required position to a danger-unavoidable position. The danger-unavoidable position is a position from which a collision cannot be avoided even if the driver starts an operation for avoiding the obstruction. In other words, within this danger-avoidable region, the subject vehicle or the driver is in a state where a danger can be avoided when the driver starts an operation for avoiding the obstruction, but the danger cannot be avoided when the driver starts no operation for avoiding the obstruction. When the subject vehicle enters the danger-avoidable region, the sequence goes to Step S 155 . When the subject vehicle does not enter the danger-avoidable region, the sequence returns to Step S 110 .  
         [0038]     At Step S 155 , the sound output device  23  is sent a signal and caused to output a sound to cause the driver to rapidly start a danger-avoidance operation. For instance, the sound is “Danger. Decelerate. An obstruction regarded as a parked vehicle is present ahead.” To avoid a danger more effectively, the sound is preferably outputted in an order of causing the presence of the danger to be recognized, indicating the next operation, and then explaining the reason. The display device  25  is also sent the signal and caused to display, for instance, a blinking image of characters indicating braking operation. Further, the steering control device  31  is sent a signal for vibrating the steering wheel, while the seat control device  37  is sent a signal for vibrating the seat.  
         [0039]     At Step S 160 , danger information A is outputted to the pre-crash safety control device  29  via the in-vehicle LAN  41 . This danger information A includes at least (i) information indicating that the subject vehicle enters a danger-avoidable region, (ii) information indicating a position of an obstruction having a possibility of colliding with the subject vehicle, and (iii) information indicating a speed and a position of the subject vehicle.  
         [0040]     At Step S 165 , it is determined whether the subject vehicle enters a danger region, which will be explained with reference to  FIG. 6A  as follows. This danger region is, for instance, from a final (or limit) position of the danger-avoidable region to the obstruction. Within the danger region, the vehicle or the driver is in a state where the collision cannot be avoided by an ordinary braking function operated by the driver. When the subject vehicle enters the danger region, the sequence goes to Step S 170 . When the subject vehicle does not enter the danger region, the sequence returns to Step S 110 .  
         [0041]     At Step S 170 , danger information B is outputted to the pre-crash safety control device  29  via the in-vehicle LAN  41 . This danger information B includes at least (i) information indicating that the subject vehicle enters a danger region, (ii) information indicating a position of an obstruction having a possibility of colliding with the subject vehicle, and (iii) information indicating a speed and a position of the subject vehicle. After the danger information B is outputted, the sequence returns to Step S 110 .  
         [0042]     (2) Region Determining Process for Temporary Stop (Refer to  FIG. 3 )  
         [0043]     The determining unit  13  starts a region determining process for a temporary stop when an ignition of the subject vehicle is turned on. Here, the determining unit  13  executes this process independently, regardless of execution of the above region determining process for an obstruction. Firstly, at Step S 310 , a vehicle speed is computed based on signals inputted from the speed sensor  19 . At Step S 315 , a position of the subject vehicle is computed based on information inputted from the position sensor  21 . At Step S 320 , map information (in detail, information of presence or absence of a temporary stop) is obtained from the storing unit  17 .  
         [0044]     At Step S 323 , it is determined whether a temporary-stop-required position where the subject vehicle needs to temporarily stop is present within a given distance from a present position of the subject vehicle (e.g., within 100 meters at 40 km/h) based on the information obtained at the preceding process at Steps S 310 , S 315 , and S 320 . When a temporary-stop-required position is determined to be present within the given distance, the sequence goes to S 325 . When a temporary-stop-required position is determined not to be present within the given distance, the sequence returns to S 310 .  
         [0045]     At Step S 325 , given information is obtained via the in-vehicle LAN  41 . This given information includes (i) information of how the driver operates the steering, from the steering control device  31 , (ii) information of how the driver operates the throttle, from the throttle control device  33 , (iii) information of how the driver operates the brake, from the brake control device  35 .  
         [0046]     At Step S 330 , it is determined whether the driver intends to stop at the temporary-stop-required position based on the information computed or obtained at Steps S 310 , S 315 , S 320 , and S 325 . This determination can be executed by various methods as follows. It can be determined whether the driver releases stepping of an accelerator pedal, or whether the driver steps on the braking pedal for temporarily stopping.  
         [0047]     At Step S 335 , the sequence is branched depending on the determination result at Step S 330 . When the driver has an intension of temporarily stopping, the sequence returns to S 310 . When the driver has no intension of temporarily stopping, the sequence goes to S 340 .  
         [0048]     At Step S 340 , it is determined whether the subject vehicle enters a warning region, which will be explained with reference to  FIG. 6B  as follows. This warning region is, for instance, within  50  meters short of an operation-required position in an approaching direction with respect to a temporary-stop-required position (a stop sign in  FIG. 6B ). The operation-required position is a position from which the driver needs to start an operation (e.g., releasing stepping on the accelerator pedal) for temporarily stopping the vehicle. Within the warning region, the vehicle or the driver is in a state where the driver needs to at least recognize the presence of the temporary-stop-required position. This warning region varies depending on a vehicle speed. When the subject vehicle enters the warning region, the sequence goes to Step S 345 . When the subject vehicle does not enter the warning region, the sequence returns to Step S 310 .  
         [0049]     At Step S 345 , the sound output device  23  is sent a signal and caused to output a sound causing the driver to recognize the presence of the temporary-stop-required position. For instance, the sound is “An intersection where this vehicle needs to temporarily stop is present 100 meters ahead. Please operate for stopping.” The display device  25  is also sent the signal and caused to display an image indicating positions of the subject vehicle and the temporary-stop-required position on a map.  
         [0050]     At Step S 350 , it is determined whether the subject vehicle enters a danger-avoidable region, which will be explained with reference to  FIG. 6B  as follows. This danger-avoidable region is, for instance, from the operation-required position to a stop-impossible position in the approaching direction with respect to the temporary-stop-required position. The stop-impossible position is a position from which the vehicle cannot stop at the temporary-stop-required position even if the driver starts an operation for stopping the vehicle. Within this danger-avoidable region, the vehicle or the driver is in a state where a temporary stop can be completed when the driver starts an operation for stopping, but the temporary stop cannot be completed when the driver starts no operation for stopping. When the subject vehicle enters the danger-avoidable region, the sequence goes to Step S 355 . When the subject vehicle does not enter the danger-avoidable region, the sequence returns to Step S 310 .  
         [0051]     At Step S 355 , the sound output device  23  is sent a signal and caused to output a sound to cause the driver to rapidly start a temporary-stop operation. For instance, the sound is “Danger. Decelerate. An intersection needing a temporary stop is present ahead.” To avoid a danger more effectively, the sound is preferably outputted in an order of causing the presence of the danger to be recognized, indicating the next operation, and then explaining the reason. The display device  25  is also sent the signal and caused to display, for instance, a blinking image of characters indicating braking operation. Further, the steering control device  31  is sent a signal for vibrating the steering wheel, while the seat control device  37  is sent a signal for vibrating the seat.  
         [0052]     At Step S 360 , danger information C is outputted to the pre-crash safety control device  29  via the in-vehicle LAN  41 . This danger information C includes at least information indicating that the subject vehicle enters a danger-avoidable region.  
         [0053]     At Step S 365 , it is determined whether the subject vehicle enters a danger region, which will be explained with reference to  FIG. 6B  as follows. This danger region is, for instance, from a final (or limit) position of the danger-avoidable region to the temporary-stop-required position. Within this danger region, the temporary stop at the temporary-stop-required position cannot be completed by an ordinary braking function operated by the driver. When the subject vehicle enters the danger region, the sequence goes to Step S 370 . When the subject vehicle does not enter the danger region, the sequence returns to Step S 310 .  
         [0054]     At Step S 370 , danger information D is outputted to the pre-crash safety control device  29  via the in-vehicle LAN  41 . This danger information D includes at least information indicating that the subject vehicle enters a danger region. After the danger information D is outputted, the sequence returns to Step S 310 .  
         [0055]     (3) Obstruction-responding Process (Refer to  FIG. 4 )  
         [0056]     An obstruction-responding process is executed by the pre-crash safety control device  29 . The pre-crash safety control device  29  starts this process when an ignition of the subject vehicle is turned on. Firstly, at Step S 210 , forward-obstruction information relating to a forward obstruction ahead of the subject vehicle is obtained from the forward radar  27 . This information includes a relative distance or a relative speed with the obstruction (or vehicle). Here, this information relates to any obstruction that is detected forward regardless of possibility of colliding with it.  
         [0057]     At Step S 215 , the forward-obstruction information is sent to the navigation device  11  via the in-vehicle LAN  41 . At Step S 220 , receiving the danger information A sent from the navigation device  11  via the in-vehicle LAN  41  is tried. As explained above, the danger information A includes at least (i) information indicating that the subject vehicle enters a danger-avoidable region, (ii) information indicating a position of an obstruction having a possibility of colliding with the subject vehicle, and (iii) information indicating a speed and a position of the subject vehicle. Even when the danger information A is not received, the sequence goes to Step S 225 .  
         [0058]     At Step S 225 , it is determined whether an obstruction that has a possibility of colliding with the subject vehicle is present based on the forward-obstruction information and the danger information A (if received at Step S 220 ). When an obstruction having a possibility of colliding with the subject vehicle is determined to be present, the sequence goes to S 230 . When an obstruction having a possibility of colliding with the subject vehicle is determined not to be present, the sequence returns to S 210 .  
         [0059]     At Step S 230 , a signal for weakly fastening the seatbelt is sent to the seatbelt control device  39  via the in-vehicle LAN  41 . The seatbelt control device  39  receives this signal to thereby operate a seatbelt fastening motor so that the driver recognizes fastening of the seatbelt.  
         [0060]     At Step S 235 , receiving the danger information B sent from the navigation device  11  via the in-vehicle LAN  41  is tried. As explained above, the danger information B includes at least (i) information indicating that the subject vehicle enters a danger region, (ii) information indicating a position of an obstruction having a possibility of colliding with the subject vehicle, and (iii) information indicating a speed and a position of the subject vehicle.  
         [0061]     At Step S 240 , it is determined whether an obstruction that may unavoidably collide with the subject vehicle is present based on the forward-obstruction information and the danger information B (if received at Step S 235 ). When an obstruction that may unavoidably collide with the subject vehicle is determined to be present, the sequence goes to S 245 . When an obstruction that may unavoidably collide with the subject vehicle is determined not to be present, the sequence returns to S 210 .  
         [0062]     At Step S 245 , a signal for strongly fastening the seatbelt is sent to the seatbelt control device  39  via the in-vehicle LAN  41 . The seatbelt control device  39  receives this signal to thereby operate the seatbelt fastening motor so that the driver can be fixed to the seat.  
         [0063]     At Step S 250 , a signal is outputted for causing the brake control device  35  to execute a braking assist operation via the in-vehicle LAN  41 . The brake control device  35  receives this signal to thereby cause the braking system to work so that a braking force with respect to the driver&#39;s braking operation is increased to more than a usual force.  
         [0064]     At Step S 255 , a signal is outputted for causing the brake control device  35  to execute an automatic braking operation via the in-vehicle LAN  41 . The brake control device  35  receives this signal to thereby cause the braking system to work so that a maximum braking force is attained regardless of the driver&#39;s braking operation.  
         [0065]     At Step S 260 , it is determined whether the subject vehicle collides with the obstruction based on information from the acceleration sensor or the like. When the subject vehicle collides with the obstruction, the process ends. When the subject vehicle does not collide with the obstruction, the sequence returns to Step S 210 .  
         [0066]     (4) Temporary-Stop-Responding Process (Refer to  FIG. 5 )  
         [0067]     A temporary-stop-responding process is executed by the pre-crash safety control device  29 . The pre-crash safety control device  29  starts this process when an ignition of the subject vehicle is turned on. Firstly, at Step S 410 , receiving the danger information C sent from the navigation device  11  via the in-vehicle LAN  41  is tried. As explained above, the danger information C includes at least information indicating that the subject vehicle enters a danger-avoidable region. Even when the danger information A is not received, the sequence goes to Step S 420 .  
         [0068]     At Step S 420 , it is determined whether the danger information C is received. When the danger information C is determined to be received, the sequence goes to Step S 430 . When the danger information C is determined not to be received, the sequence returns to Step S 410 .  
         [0069]     At Step S 430 , a signal for weakly fastening the seatbelt is sent to the seatbelt control device  39  via the in-vehicle LAN  41 . The seatbelt control device  39  receives this signal to thereby operate the seatbelt fastening motor so that the driver recognizes fastening of the seatbelt.  
         [0070]     At Step S 440 , receiving the danger information D sent from the navigation device  11  via the in-vehicle LAN  41  is tried. As explained above, the danger information D includes at least information indicating that the subject vehicle enters a danger region.  
         [0071]     At Step S 450 , it is determined whether the danger information D is received. When the danger information D is determined to be received, the sequence goes to Step S 460 . When the danger information D is determined not to be received, the sequence returns to Step S 410 .  
         [0072]     At Step S 460 , a signal for strongly fastening the seatbelt is sent to the seatbelt control device  39  via the in-vehicle LAN  41 . The seatbelt control device  39  receives this signal to thereby operate the seatbelt fastening motor so that the driver can be fixed to the seat.  
         [0073]     At Step S 470 , a signal is outputted for causing the brake control device  35  to execute a braking assist operation via the in-vehicle LAN  41 . The brake control device  35  receives this signal to thereby cause the braking system to work so that a braking force with respect to the driver&#39;s braking operation is increased to more than a usual force.  
         [0074]     At Step S 480 , a signal is outputted for causing the brake control device  35  to execute an automatic braking operation via the in-vehicle LAN  41 . The brake control device  35  receives this signal to thereby cause the braking system to work so that a maximum braking force is attained regardless of the driver&#39;s braking operation.  
         [0075]     (Effects)  
         [0076]     Thus, the navigation device  11  executes region determination with respect to an obstruction based on a relative distance and a relative speed between a subject vehicle and an obstruction. The navigation device  11  thereby determines various driving states, e.g., (i) a state where a driver needs to be warned, (ii) a state where an avoidance operation needs to be started, and (iii) a state where an action anticipating a collision needs to be operated. Then a signal based on the determination results is sent to other relevant devices (e.g., the sound output device  23 , the display device  25 , the pre-crash safety control device  29 , or the like) to thereby cause the relevant devices to properly operate. The navigation device  11  determines the driving states by synthesizing various information and then comprehensively output signals for activating other devices or signals for determining whether other devices should start. Therefore, this system is more effective and other devices more cooperatively work, than a system where each of other devices determines the operation by individually collecting information.  
         [0077]     The navigation device  11  executes region determination with respect to a temporary stop based on a distance with the temporary-stop-required position and a speed of the subject vehicle. The navigation device  11  thereby determines various driving states, e.g., (i) a state where a driver needs to be warned, (ii) a state where a stop operation needs to be started, and (iii) a state where an emergency stop needs to be operated. Then a signal based on the determination results is sent to other relevant devices (e.g., the sound output device  23 , the display device  25 , the pre-crash safety control device  29 , or the like) to thereby cause the relevant devices to properly operate. The navigation device  11  determines the driving states by synthesizing various information and then comprehensively output signals for activating other devices or signals for determining whether other devices should start. Therefore, this system is more effective and other devices more cooperatively work, than a system where each of other devices determines the operation by individually collecting information.  
         [0078]     (Others)  
         [0079]     (1) The system can further include a communications device  50  as a communicating unit so that an obstruction having a possibility of colliding with a subject vehicle can be recognized based on information obtained by this communications device  50  in addition to the information obtained as explained above. For instance, this communications device  50  performs communications with another vehicle (i.e., inter-vehicle communications), communications with a road or a roadside, or communications with an information center to thereby acquire traffic regulation or congestion information, or obstruction information obtained by another vehicle. This results in high accuracy in recognizing obstructions. Furthermore, for instance, this communications device  50  communicates using radio waves or the like with a comparable navigation device having the same function of the navigation device  11 . Both navigation devices can be designed to exchange information to be used for executing the above-explained processes. In this case, each navigation device can execute the processes by recognizing obstructions other than the obstruction detected by the forward radar  27  provided in each of the vehicles. The communications device  50  can be connected directly with the navigation device, or can be connected via the in-vehicle LAN  41  with the navigation device.  
         [0080]     (2) The system can further include an in-vehicle camera  51  photographing a forward scenery ahead of the subject vehicle. Based on an image of a forward traffic signal photographed by the camera  51 , states (green, yellow, or red signal) of the traffic signal can be determined. The region determination with respect to a temporary stop can be thereby executed. In other words, when there is an intersection whose traffic signal is red ahead of the subject vehicle, this intersection is regarded as a temporary-stop-required position. The region determination with respect to a temporary stop is then executed. In this case, the navigation device  11  can recognize more temporary-stop-required positions, which enhances safety. Further, when a traffic infrastructure capable of providing the states of a traffic signal is present, it can be designed that the states of a traffic signal are obtained from the traffic infrastructure.  
         [0081]     (3) Information of a temporary-stop-required position obtained from a map database can include the following: temporary-stop position information; vehicle-train intersection information; parking-lot site information; or cliff or drop-off information in seaside or mountainous areas. Furthermore, temporary-stop-required position information externally obtained via the communications device  50  explained above can include the following: traffic signal color information at intersections; fallen rock information; or cave-in information. The information can be used for helping prevent mis-operation (downfall or the like) in a multi-layered parking structure, a downfall to the sea in a port, or the like. Further, the information can be used for anticipating a fallen rock, a cave-in, or the like.  
         [0082]     (4) In the above embodiment, an obstruction or a temporary-stop-required position is regarded as a prevention-necessitating target. This prevention-necessitating target has a possibility of giving danger to the subject vehicle in a case that the subject vehicle does not anticipate (or respond to) danger relating to this prevention-necessitating target. In sum, the subject vehicle is necessitated to prevent the danger relating to the prevention-necessitating target.  
         [0083]     It will be obvious to those skilled in the art that various changes may be made in the above-described embodiments of the present invention. However, the scope of the present invention should be determined by the following claims.