Patent Publication Number: US-2022234597-A1

Title: Vehicle control device, storage medium for storing computer program for vehicle control, and method for controlling vehicle

Description:
FIELD 
     The present invention relates to a vehicle control device, to a storage medium that stores a computer program for vehicle control, and to a method for controlling a vehicle. 
     BACKGROUND 
     An automatic control device mounted in a vehicle creates a navigation route for the vehicle based on the current location of the vehicle, the destination location of the vehicle, and map information, and controls the vehicle so that it travels along the navigation route. 
     The automatic control device controls operation of the vehicle so that a safe distance is maintained between the vehicle and other vehicles. When it has been determined that a safe distance cannot be maintained between the vehicle and another vehicle by automatic control, the automatic control device switches operation of the vehicle from automatic control to manual control, transferring control of the vehicle to the driver. 
     When there is a problem with the driver, the automatic control device controls the vehicle so that it stops on the traveling lane in which it is traveling. It is not possible to transfer of control of the vehicle to the driver when the automatic control device has determined that safe traveling is not possible. 
     Japanese Unexamined Patent Publication No. H9-249104, for example, proposes an automatic braking device for a vehicle that immediately flashes a brake lamp during an automatic brake notice time period when the alertness level of the driver has fallen below the alertness level at the start of braking, and then begins a braking operation to generate braking force. 
     SUMMARY 
     With the automatic braking device for a vehicle described in Japanese Unexamined Patent Publication No. H9-249104, since the brake light is immediately activated and the brake is operated if the driving alertness level of the driver falls below the alertness level at the start of braking even when the vehicle is traveling at a relatively high speed, this has potentially caused drivers of subsequent vehicles to become startled, thus interfering with traffic. 
     It is therefore an object of the present invention to provide a vehicle control device that can immediately control the speed of the vehicle without activating a brake light so as to avoid interfering with traveling of subsequent vehicles when it has been determined that the level of active operation by the driver is low and the vehicle is traveling at a relatively high speed. 
     One embodiment of the invention provides a vehicle control device. The vehicle control device has a driver determination unit that determines the level of active operation by the driver, a speed determination unit that determines the relationship between the speed of the vehicle and a predetermined reference speed, and a drive planning unit that generates a first driving plan whereby a first deceleration is used to decelerate the vehicle without activating the brake light when it has been determined that the level of active operation by the driver is lower than the predetermined reference level and the speed of the vehicle is faster than the reference speed, and generates a second driving plan whereby a second deceleration that is greater than the first deceleration is used to decelerate the vehicle when it has been determined that the level of active operation by the driver is lower than the predetermined reference level and the speed of the vehicle is equal to or below the reference speed. 
     The vehicle control device further has a vehicle control unit that controls operation of the vehicle based on the first driving plan, wherein the vehicle control unit controls the vehicle so that the vehicle is accelerated so that deceleration of the vehicle reaches the first deceleration when deceleration of the vehicle controlled based on the first driving plan is greater than the first deceleration. 
     The drive planning unit in the vehicle control device preferably also generates the second driving plan so that the vehicle is moved to the shoulder adjacent to the traveling lane in which the vehicle is traveling and stopped after the vehicle has been moved to the shoulder. 
     The drive planning unit of the vehicle control device also preferably generates a second driving plan so that an emergency flash indicator flashes when it has been determined that the level of active operation by the driver is lower than a second predetermined reference level which is lower than the predetermined reference level and the speed of the vehicle is equal to or below the reference speed, and the brake light activates and the emergency flash indicator turns off when it has been determined that the level of active operation by the driver is lower than the second predetermined reference level and a braking device is being used. 
     According to another embodiment, a non-transitory storage medium is provided which stores a computer program for vehicle control. The computer program for vehicle control causes a processor to determine the level of active operation by the driver, determine the relationship between the speed of the vehicle and a predetermined reference speed, and, generate a first driving plan whereby a first deceleration is used to decelerate the vehicle without activating a brake light when it has been determined that the level of active operation by the driver is lower than the predetermined reference level and the speed of the vehicle is faster than the reference speed, and generate a second driving plan whereby a second deceleration that is greater than the first deceleration is used to decelerate the vehicle when it has been determined that the level of active operation by the driver is lower than the predetermined reference level and the speed of the vehicle is equal to or below the reference speed. 
     Another embodiment of the invention provides a method for controlling a vehicle. In the method for controlling a vehicle, the vehicle control device determines the level of active operation by the driver, determines the relationship between the speed of the vehicle and a predetermined reference speed and, generates a first driving plan whereby a first deceleration is used to decelerate the vehicle without activating a brake light when it has been determined that the level of active operation by the driver is lower than the predetermined reference level and the speed of the vehicle is faster than the reference speed, and generates a second driving plan whereby a second deceleration that is greater than the first deceleration is used to decelerate the vehicle when it has been determined that the level of active operation by the driver is lower than the predetermined reference level and the speed of the vehicle is equal to or below the reference speed. 
     With the vehicle control device of the invention, when it has been determined that the level of active operation by the driver is low and the vehicle is traveling at a relatively high speed, the vehicle can be decelerated without activating the brake light until the speed of the vehicle has fallen below the predetermined reference speed, so as to avoid interfering with traveling of subsequent vehicles. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating in overview the operation of a vehicle control system as an example of a vehicle control device of the embodiment. 
         FIG. 2  is a general schematic drawing of a vehicle in which a vehicle control system of the embodiment is mounted. 
         FIG. 3  is an operation flow chart for deceleration plan processing by a vehicle control system of the embodiment. 
         FIG. 4  is a diagram illustrating operation of a vehicle control system ( 1 ). 
         FIG. 5  is a diagram illustrating operation of a vehicle control system ( 2 ). 
         FIG. 6  is a diagram illustrating operation of a vehicle control system ( 3 ). 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
       FIG. 1  is a diagram illustrating in overview the operation of a vehicle control system  1  as an example of a vehicle control device of the embodiment. Operation relating to deceleration plan processing by the vehicle control system  1  disclosed herein will now be described in overview with reference to  FIG. 1 . 
     In the example shown in  FIG. 1 , a vehicle  10  travels on a traffic lane  51  of a road  50  having two traffic lanes  51 ,  52  and a shoulder  53 . The traffic lanes  51  and  52  are divided by a lane marking line  54 , and the traffic lane  51  and shoulder  53  are divided by a lane marking line  55 . 
     The vehicle control system  1  installed in the vehicle  10  automatically controls driving of the vehicle  10 . The vehicle control system  1  monitors the level of active operation by the driver, in order to determine whether or not control of the vehicle can be transferred to the driver when operation of the vehicle  10  can no longer be automatically controlled. 
     At time T 101 , the vehicle  10  is traveling on the traffic lane  51 , and the vehicle control system  1  determines that the level of active operation by the driver is equal to or above the predetermined reference level. 
     At time T 102 , the vehicle control system  1  determines that the level of active operation by the driver is lower than the predetermined reference level, and warns the driver that they should be active in driving. Since the speed of the vehicle  10  is faster than the reference speed, the vehicle control system  1  also controls operation of the vehicle  10  so that a first deceleration whereby the vehicle  10  is decelerated to a level that does not interfere with traveling of subsequent vehicles, is used to decelerate the vehicle  10  without activating the brake light. 
     At time T 103 , the level of active operation by the driver continues to be lower than the predetermined reference level and the speed of the vehicle  10  has reached equal to or below the reference speed, and therefore the vehicle control system  1  controls the operation of the vehicle  10  so that a second deceleration that is greater than the first deceleration is used to decelerate the vehicle  10 . As a result, the vehicle  10  uses the braking device for further deceleration while activating the brake light. 
     At time T 104 , the level of active operation by the driver continues to be low even after a predetermined time has elapsed after the warning has been given to the driver. The vehicle control system  1  determines that there is a problem with the driver, and generates a driving plan to move the vehicle  10  to the shoulder  53  and stop it. The vehicle  10  therefore moves from the traffic lane  51  to the shoulder  53  and stops on the shoulder at time T 108 . 
     The vehicle control system  1  is thus designed so that, when it has been determined that the level of active operation by the driver is low and the vehicle  10  is traveling at a relatively high speed, it can cause the vehicle  10  to decelerate without activating the brake light until the speed of the vehicle  10  has fallen below the predetermined reference speed, so as to avoid interfering with traveling of subsequent vehicles. 
       FIG. 2  is a general schematic drawing of a vehicle  10  in which the vehicle control system  1  is installed. The vehicle  10  comprises a camera  2 , radar sensors  3   a  to  3   f , emergency flashing lights (turn signals)  4   a  to  4   f , brake lights  5   a ,  5   b , a positioning information receiver  6 , a navigation device  7 , a user interface (UI)  8 , a speed sensor  9 , a map information storage device  11 , a monitoring device  12 , a location estimating device  13 , an object detector  14 , a traveling lane planning device  15 , a drive planning device  16 , a vehicle control device  17 , a driver determination device  18  and a speed determination device  19 . The map information storage device  11 , monitoring device  12 , location estimating device  13 , object detector  14 , traveling lane planning device  15 , drive planning device  16 , vehicle control device  17 , driver determination device  18  and speed determination device  19  constitute the vehicle control system  1 . The vehicle  10  may also have a LiDAR sensor to detect road features or other objects. 
     The drive planning device  16 , driver determination device  18  and speed determination device  19  cooperate to generate a driving plan whereby, when it has been determined that the level of active operation by the driver is lower than the predetermined reference level, and the vehicle  10  is traveling at a relatively high speed, the speed of the vehicle  10  is caused to decelerate so as not to interfere with traveling of subsequent vehicles. 
     The camera  2 , radar sensors  3   a  to  3   f , emergency flashing lights (turn signals)  4   a  to  4   f , brake lights  5   a ,  5   b , positioning information receiver  6 , navigation device  7 , user interface (UI)  8 , speed sensor  9 , map information storage device  11 , monitoring device  12 , location estimating device  13 , object detector  14 , traveling lane planning device  15 , drive planning device  16 , vehicle control device  17 , driver determination device  18  and speed determination device  19  are connected in a communicable manner through an in-vehicle network  22  that conforms to controller area network standards. 
     The camera  2  is an example of an imaging unit provided in the vehicle  10 . The camera  2  is mounted inside the vehicle  10  and directed toward the front of the vehicle  10 . The camera  2 , for example, takes a camera image in which the environment of a predetermined region ahead of the vehicle  10  is shown, at a predetermined cycle. The camera image can show the road in the predetermined region ahead of the vehicle  10 , and road features such as surface lane marking lines on the road. The camera  2  has a 2D detector composed of an array of photoelectric conversion elements with visible light sensitivity, such as a CCD or C-MOS, and an imaging optical system that forms an image of the photographed region on the 2D detector. 
     Each time a camera image is taken, the camera  2  outputs the camera image and the camera image photograph time at which the camera image was taken, through the in-vehicle network  22  to the location estimating device  13  and object detector  14 . The camera image is also used for processing at the location estimating device  13  to estimate the location of the vehicle  10 . At the object detector  14 , the camera image is used for processing to detect other objects surrounding the vehicle  10 . 
     The radar sensors  3   a  to  3   f  are mounted on the outer sides of the vehicle  10 , for example, being directed toward the front, left front, right front, rear, left rear and right rear of the vehicle  10 , respectively. The radar sensors  3   a  to  3   f  respectively synchronize and emit millimeter waves toward the front, left front, right front, rear, left rear and right rear of the vehicle  10 , at a reflected wave information acquisition time set with a predetermined cycle, and receive a reflected wave that has been reflected from a reflector. The time required for the reflected wave to return contains information for the distance between the vehicle  10  and other objects located in the direction in which the millimeter waves have been emitted. Each of the radar sensors  3   a  to  3   f  outputs the reflected wave information that includes the millimeter wave emission direction and the time required for the reflected wave to return, together with the reflected wave information acquisition time at which the millimeter waves were emitted, through the in-vehicle network  22  to the object detector  14 . At the object detector  14 , the reflected wave information is used for processing to detect other objects surrounding the vehicle  10 . 
     The emergency flashing lights (turn signals)  4   a  to  4   f  are mounted on the outer sides of the vehicle  10 , and are directed toward the left front, left, left rear, right front, right and right rear of the vehicle  10 . The emergency flashing lights (turn signals)  4   a  to  4   f  are controlled by the vehicle control system  1 . When the vehicle  10  is in a state of emergency, all of the emergency flashing lights  4   a  to  4   f  are activated. When the vehicle  10  is to change direction toward the left, the turn signals  4   a  to  4   c  are activated, and when the vehicle  10  is to change direction toward the right, the turn signals  4   d  to  4   f  are activated. 
     The brake lights  5   a ,  5   b  are mounted on the outer side of the vehicle  10 , for example, and directed toward the left rear and right rear of the vehicle  10 . The brake lights  5   a ,  5   b  are controlled by the vehicle control system  1 . The brake lights  5   a ,  5   b  are activated when the braking device (not shown) of the vehicle  10  is being operated, notifying subsequent vehicles that the braking device is activated for deceleration. 
     The positioning information receiver  6  outputs positioning information that represents the current location of the vehicle  10 . The positioning information receiver  6  may be a GNSS receiver, for example. The positioning information receiver  6  outputs positioning information and the positioning information acquisition time at which the positioning information has been acquired, to the navigation device  7  and map information storage device  11 , each time positioning information is acquired at a predetermined receiving cycle. 
     Based on the navigation map information, the destination location of the vehicle  10  input through the UI  8 , and positioning information representing the current location of the vehicle  10  input from the positioning information receiver  6 , the navigation device  7  creates a navigation route from the current location to the destination location of the vehicle  10 . The navigation route includes information relating to the locations of right turns, left turns, merging and branching. When the destination location has been newly set or the current location of the vehicle  10  has exited the navigation route, the navigation device  7  creates a new navigation route for the vehicle  10 . Every time a navigation route is created, the navigation device  7  outputs the navigation route to the location estimating device  13 , the traveling lane planning device  15  and the drive planning device  16 , via the in-vehicle network  22 . 
     The UI  8  is an example of a notification unit. The UI  8  is controlled by the navigation device  7 , monitoring device  12  and drive planning device  16  to give the driver traveling information for the vehicle  10  and a warning for recommending active driving. The UI  8  also creates an operation signal in response to operation of the vehicle  10  by the driver. The traveling information of the vehicle  10  includes information relating to the current location of the vehicle and the current and future route of the vehicle, such as the navigation route. The UI  8  has a display device  81  such as a liquid crystal display or touch panel, for display of the traveling information and warnings. The UI  8  may also have an acoustic output device (not shown) to notify the driver of traveling information and warnings. The UI  8  also has a touch panel or operating button, for example, as an input device for inputting operation information from the driver to the vehicle  10 . The operation information may be, for example, a destination location, transit points, vehicle speed or other vehicle control information. The UI  8  outputs the input operation information to the navigation device  7  and the drive planning device  16 , via the in-vehicle network  22 . 
     The speed sensor  9  detects speed information representing the speed of the vehicle  10 , and outputs it to the speed determination device  19  via the in-vehicle network  22 . The speed sensor  9  detects the rotational speed of the tires of the vehicle  10 , and outputs speed information representing the rotational speed to the speed determination device  19 . 
     The map information storage device  11  stores wide-area map information for a relatively wide area (an area of 10 to 30 km 2 , for example) that includes the current location of the vehicle  10 . The wide-area map information preferably has high precision map information including three-dimensional information for the road surface, information for the types and locations of structures and road features such as road lane marking lines, and the legal speed limit for the road. The map information storage device  11  receives the wide-area map information from an external server via a base station, by wireless communication through a wireless communication device (not shown) mounted in the vehicle  10 , in relation to the current location of the vehicle  10 , and stores it in the storage device. Each time positioning information is input from the positioning information receiver  6 , the map information storage device  11  refers to the stored wide-area map information and outputs map information for a relatively narrow area including the current location represented by the positioning information (for example, an area of 100 m to 10 km 2 ), through the in-vehicle network  22  to the location estimating device  13 , the traveling lane planning device  15  and the drive planning device  16 . 
     The monitoring device  12  monitors the state of the driver, and when activity of the driver related to driving has not been detected, it generates a “non-active driving signal”, indicating that activity of the driver relating to driving has not been detected. The monitoring device  12  outputs the non-active driving signal to the drive planning device  16  via the in-vehicle network  31 . The monitoring device  12  comprises a surveillance camera  121  that photographs a head image that includes the head of the driver, a touch sensor  122  that detects when the driver is holding the steering wheel, and a torque sensor  123  that detects the torque of the steering wheel. Based on an image of the head photographed at a monitoring time with a predetermined cycle, the monitoring device  12  detects the driver&#39;s line-of-sight direction, the degree to which the eyes are open (hereunder also referred to as “degree of eye opening”) and the degree to which the mouth is open (hereunder also referred to as “degree of mouth opening”), and determines the level of active operation by the driver, based on the detected line-of-sight direction, degree of eye opening and degree of mouth opening. When the line-of-sight direction is out of a predetermined range that includes the front of the vehicle  10 , the monitoring device  12  determines that the level of active operation by the driver is low. When the degree of eye opening is less than a predetermined reference value for the degree of eye opening or the degree of mouth opening is greater than a predetermined reference value for the degree of mouth opening, the monitoring device  12  likewise determines that the level of active operation by the driver is low. On the other hand, when the line-of-sight direction is within a predetermined reference level range including the front of the vehicle  10 , or the degree of eye opening is greater than a predetermined reference value for the degree of eye opening, or the degree of mouth opening is less than a predetermined reference value for the degree of mouth opening, the monitoring device  12  determines that the level of active operation by the driver is high. 
     When it has been determined that the level of active operation by the driver is low, the monitoring device  12  warns the driver through the UI  8  to recommend active operation of the vehicle. The monitoring device  12  also outputs a warning signal indicating that the driver has been warned, to the driver determination device  18  via the in-vehicle network  22 . Determination by the monitoring device  12  that the level of active operation by the driver is low is an example of determination that the level of active operation by the driver is lower than the predetermined reference level. If, within a predetermined time after having alerted the driver, it has been determined that the level of active operation by the driver is high based on the detected line-of-sight direction, degree of eye opening and degree of mouth opening, the monitoring device  12  determines that the driver is actively operating the vehicle. If, within a predetermined time after having alerted the driver, the touch sensor  122  has detected that the driver is holding the steering wheel, or the torque sensor  123  has detected operation of the steering wheel by the driver, the monitoring device  12  determines that the driver is actively operating the vehicle. If, within a predetermined time after having alerted the driver, operation of the accelerator pedal or brake pedal by the driver has been detected, the monitoring device  12  likewise determines that the driver is actively operating the vehicle. On the other hand, when it has not been determined that the level of active operation by the driver is high, and the touch sensor  122  has not detected that the driver is holding the steering wheel, and the torque sensor  123  has not detected operation of the steering wheel by the driver, and operation of the accelerator pedal or brake pedal by the driver has not been detected, within a predetermined time after having alerted the driver, then it is determined that the driver is not actively operating the vehicle. The monitoring device  12  also generates a non-active driving signal indicating that activity related to operation by the driver has not been detected. Determination by the monitoring device  12  that the driver is not actively driving is an example of determination that the level of active operation by the driver is lower than the second predetermined reference level which is lower than the predetermined reference level. The monitoring device  12  outputs the non-active driving signal to the driver determination device  18  and drive planning device  16 . This is only one example of generating a non-active driving signal, and the monitoring device  12  may use another method to determine whether or not a non-active driving signal is to be generated. 
     The location estimating device  13  estimates the location of the vehicle  10  at the camera image photograph time, based on the road features surrounding the vehicle  10  represented in the camera image. For example, the location estimating device  13  compares lane marking lines identified in the camera image with lane marking lines represented in the map information input from the map information storage device  11 , and determines the estimated location and estimated declination of the vehicle  10  at the camera image photograph time. The location estimating device  13  estimates the road traveling lane where the vehicle  10  is located, based on the lane marking lines represented in the map information and on the estimated location and estimated declination of the vehicle  10 . Each time the estimated location, estimated declination and traveling lane of the vehicle  10  are determined at the camera image photograph time, the location estimating device  13  outputs this information to the object detector  14 , traveling lane planning device  15 , drive planning device  16  and vehicle control device  17 . 
     The object detector  14  detects other objects around the vehicle  10  and their types (for example, vehicles) based on the camera image and reflected wave information. Other objects also include other vehicles traveling around the vehicle  10 . The object detector  14  tracks other detected objects and determines the trajectories of the other objects. In addition, the object detector  14  identifies the traveling lanes in which the other objects are traveling, based on the lane marking lines represented in the map information and the locations of the objects. The object detector  14  outputs object detection information which includes information representing the types of other objects that were detected, information indicating their locations, and also information indicating their traveling lanes, to the traveling lane planning device  15  and drive planning device  16 . 
     At a traveling lane-planning creation time set in a predetermined cycle, the traveling lane planning device  15  selects a traffic lane on the road on which the vehicle  10  is traveling, within the nearest driving zone (for example, 10 km) selected from the navigation route, based on the map information, the navigation route and surrounding environment information and the current location of the vehicle  10 , and creates a traveling lane plan representing the scheduled traveling lane for traveling of the vehicle  10 . For example, the traveling lane planning device  15  creates a traveling lane plan for the vehicle  10  to travel on a traffic lane other than a overtaking lane. Each time a traveling lane plan is created, the traveling lane planning device  15  outputs the traveling lane plan to the drive planning device  16 . 
     The traveling lane planning device  15  also determines whether or not a lane change is necessary within the nearest driving zone selected from the navigation route, based on the map information, the navigation route and the current location of the vehicle  10 . The traveling lane planning device  15  may further utilize surrounding environment information or vehicle status information for determination of whether or not a lane change is necessary. The surrounding environment information includes the locations and speeds of other vehicles traveling around the vehicle  10 . The vehicle status information includes the current location of the vehicle  10 , and the vehicle speed, acceleration and traveling direction. Specifically, the traveling lane planning device  15  determines whether or not a lane change is necessary for moving to a traffic lane toward the destination location of the vehicle  10 , based on the navigation route and the current location of the vehicle  10 . Determination is made of whether or not the vehicle  10  is approaching another road that merges ahead from the traveling route on which it is currently traveling (merge), or the vehicle  10  is exiting onto another road branching out ahead from the traveling route (branch). Since merging and branching involve movement of the vehicle from a lane of the traveling route to a lane in another road, a lane change is carried out. 
     At a driving plan creation time set with a predetermined cycle, the drive planning device  16  carries out driving plan processing in which it creates a driving plan representing the scheduled traveling trajectory of the vehicle  10  up until a predetermined time (for example, 5 seconds), based on the traveling lane plan, the map information, the current location of the vehicle  10 , the surrounding environment information and the vehicle status information. The driving plan is represented as a combination of the target location of the vehicle  10  and the target vehicle speed at the target location, at each time from the current time until the predetermined time. The cycle in which the driving plan is created is preferably shorter than the cycle in which the traveling lane plan is created. When the traveling lane plan includes a lane change wherein the vehicle  10  is to move between traffic lanes, the drive planning device  16  creates a driving plan that includes the lane change, in such a manner that a distance more than a predetermined distance can be maintained between the vehicle  10  and other vehicles. When the traveling lane plan includes a lane change wherein the vehicle  10  is to move between traffic lanes, but a distance more than the predetermined distance cannot be ensured between the vehicle  10  and another vehicle, the drive planning device  16  creates a driving plan for stopping the vehicle. The drive planning device  16  outputs a driving plan to the vehicle control device  17  for each driving plan created. In deceleration plan processing by the vehicle control system  1 , when it has been determined that the level of active operation by the driver is lower than the predetermined reference level and the speed of the vehicle  10  is faster than the reference speed, the drive planning device  16  generates a first driving plan whereby the first deceleration is used to decelerate the vehicle  10  without activating the brake lights  5   a ,  5   b . Also, in deceleration plan processing by the vehicle control system  1 , when it has been determined that the level of active operation by the driver is lower than the predetermined reference level and the speed of the vehicle  10  is equal to or below the reference speed, the drive planning device  16  generates a second driving plan whereby a second deceleration that is greater than the first deceleration is used to decelerate the vehicle  10 . Generation of the driving plan to decelerate the vehicle  10  by the drive planning device  16  will be described below, together with explanation of the deceleration plan processing by the vehicle control system  1 . 
     The vehicle control device  17  controls each unit of the vehicle  10  based on the current location of the vehicle  10  and the vehicle speed and yaw rate, as well as on the driving plan generated by the drive planning device  16 , so that the vehicle  10  travels along the navigation route. For example, the vehicle control device  17  determines the steering angle, acceleration and angular acceleration of the vehicle  10  according to the driving plan and the speed and yaw rate of the vehicle  10 , and sets the amount of steering, and the accelerator or brake level, so as to match that steering angle, accelerator level and angular acceleration. The vehicle control device  17  also outputs a control signal corresponding to a set steering amount, to an actuator (not shown) that controls the steering wheel for the vehicle  10 . The vehicle control device  17  also determines the amount of fuel injection according to a set accelerator level, and outputs a control signal corresponding to the amount of fuel injection to a drive unit (not shown) of the engine of the vehicle  10 . Alternatively, the vehicle control device  17  may output a control signal corresponding to a set brake level to the brake (not shown) of the vehicle  10 . 
     In deceleration plan processing by the vehicle control system  1 , the driver determination device  18  determines the level of active operation by the driver, while the speed determination device  19  determines the relationship between the speed of the vehicle  10  and the predetermined reference speed. 
     The map information storage device  11 , monitoring device  12 , location estimating device  13 , object detector  14 , traveling lane planning device  15  and vehicle control device  17  comprise a communication interface (not shown), a memory (not shown) and a processor (not shown). The communication interface has an interface circuit to connect each device with the in-vehicle network  22 . The drive planning device  16  has a communication interface  161 , a memory  162  and a processor  163 . The driver determination device  18  has a communication interface  181 , a memory  182  and a processor  183 . The speed determination device  19  has a communication interface  191 , a memory  192  and a processor  193 . 
     All of some of the functions of the map information storage device  11 , monitoring device  12 , location estimating device  13 , object detector  14 , traveling lane planning device  15 , drive planning device  16 , vehicle control device  17 , driver determination device  18  and speed determination device  19  are, for example, functional modules realized by a computer program that is operated in a processor. Alternatively, the functional module of the processor may be a specialized computing circuit in the processor. The processor comprises one or more CPUs (Central Processing Units) and their peripheral circuits. The processor may also have other computing circuits such as a logical operation unit, numerical calculation unit or graphic processing unit. The memory of each device is an example of a memory unit, and it has a volatile semiconductor memory and a non-volatile semiconductor memory, for example. The memory stores an application computer program and various data to be used for information processing carried out by the processor of each device. 
     The map information storage device  11 , monitoring device  12 , location estimating device  13 , object detector  14 , traveling lane planning device  15 , drive planning device  16 , vehicle control device  17 , driver determination device  18  and speed determination device  19  were explained above as separate devices, but all or some of them may be constructed in a single device. 
     The drive planning device  16 , driver determination device  18  and speed determination device  19  cooperate to execute deceleration plan processing whereby, when it has been determined that the level of active operation by the driver is lower than the predetermined reference level, and the vehicle  10  is traveling at a relatively high speed, the speed of the vehicle  10  is caused to decelerate so as not to interfere with traveling of subsequent vehicles. 
       FIG. 3  is an example of an operation flow chart for deceleration plan processing by the vehicle control system  1 . Processing by the vehicle control system  1  will be described below with reference to  FIG. 3 . The vehicle control system  1  repeatedly carries out deceleration plan processing according to the operation flow chart shown in  FIG. 3 , while the vehicle  10  is traveling. 
     First, the driver determination device  18  of the vehicle control system  1  determines whether or not the level of active operation by the driver is lower than the predetermined reference level at a driver determination time that is set with a predetermined cycle (step S 101 ). When a warning signal or non-active driving signal has been input through the monitoring device  12 , the driver determination device  18  determines that the level of active operation by the driver is lower than the predetermined reference level (step S 101 -Yes). When the line-of-sight direction of the driver is outside of the predetermined range that includes the front of the vehicle  10 , or the degree of eye opening of the driver is less than the predetermined reference value for the degree of eye opening, or the degree of mouth opening of the driver is greater than the predetermined reference value for the degree of mouth opening, the monitoring device  12  outputs a warning signal to the driver determination device  18 , so that when a warning signal is input, the driver determination device  18  determines that the level of active operation by the driver is lower than the predetermined reference level. Since the monitoring device  12  outputs a non-active driving signal to the driver determination device  18  when the level of active operation by the driver has not been determined to be high within the predetermined time after having alerted the driver, the driver determination device  18  determines that the level of active operation by the driver is lower than the predetermined reference level when a non-active driving signal has been input. 
     When a warning signal or non-active driving signal has not been input from the monitoring device  12 , on the other hand, the driver determination device  18  determines that the level of active operation by the driver is not lower than the predetermined reference level (no problem) (step S 101 -No), and operation for deceleration plan processing by the vehicle control system  1  is complete. 
     When it has been determined that the level of active operation by the driver is lower than the predetermined reference level, the speed determination device  19  of the vehicle control system  1  determines the relationship between the speed of the vehicle  10  and the reference speed (step S 102 ). First, the speed determination device  19  determines the speed of the vehicle  10  based on speed information input from the speed sensor  9 . For example, the speed determination device  19  determines the speed of the vehicle  10  based on the rotational speed of the tires of the vehicle  10 , as an example of speed information. The relationship between the region and the reference speed for the region are stored in a memory  192  of the speed determination device  19 . The speed determination device  19  determines whether or not the speed of the vehicle  10  is lower than the reference speed, based on the reference speed for the region that includes the current location of the vehicle  10 , read out from the memory  192 . The speed determination device  19  notifies the drive planning device  16  of the determination results for the relationship between the speed of the vehicle  10  and the reference speed. 
     When the speed of the vehicle  10  is faster than the reference speed (step S 102 -Yes), the drive planning device  16  of the vehicle control system  1  generates a first driving plan whereby a first deceleration is used to decelerate the speed of the vehicle  10  without activating the brake lights  5   a ,  5   b  (step S 103 ), while the vehicle control device  17  is also notified of the driving plan. The drive planning device  16  may generate the first driving plan so as to include the period in which the first deceleration is used to decelerate the vehicle  10 , and a period in which it is not decelerating. The drive planning device  16  may also generate the first driving plan so that the first deceleration is changed during the first driving plan to another value within the range lower than the second deceleration. Operation relating to the deceleration plan processing by the vehicle control system  1  is thus complete. 
     On the other hand, when the speed of the vehicle  10  is equal to or below the reference speed (step S 102 -No), the drive planning device  16  determines whether or not the speed of the vehicle is faster than the second reference speed which is slower than the reference speed (step S 104 ). When the speed of the vehicle  10  is faster than the second reference speed (step S 104 -Yes), the drive planning device  16  generates a second driving plan whereby the second deceleration that is greater than the first deceleration is used to decelerate the speed of the vehicle  10  (step S 105 ). The drive planning device  16  may generate the second driving plan so as to include the period in which the second deceleration is used to decelerate the vehicle  10 , and a period in which it is not decelerating. The drive planning device  16  may also generate the second driving plan so that the second deceleration is changed during the second driving plan to another value within a range higher than the first deceleration. 
     The drive planning device  16  may also generate the second driving plan so that when the speed of the vehicle is equal to or below the reference speed and a non-active driving signal is input from the monitoring device  12 , the vehicle  10  is moved to the shoulder  53  adjacent to the traffic lane  51  in which the vehicle  10  is traveling, and stopped. Specifically, the drive planning device  16  sets a target location on the shoulder  53  where the vehicle  10  can be stopped within a predetermined range from the current location of the vehicle  10 , based on the current location of the vehicle  10 , the map information and the speed of the vehicle  10 . In addition, the drive planning device  16  generates a second driving plan whereby, after decelerated movement from the current location of the vehicle  10  toward the target location on the shoulder  53  while the vehicle  10  activates the turn signal, the vehicle is stopped at the target location on the shoulder  53 . The drive planning device  16  generates the second driving plan so that when the braking device is used, the brake lights  5   a ,  5   b  are activated and the emergency flash indicators  4   a  to  4   f  are turned off. The drive planning device  16  notifies the vehicle control device  17  of the second driving plan. Operation relating to the deceleration plan processing by the vehicle control system  1  is thus complete. 
     However, when the speed of the vehicle  10  is equal to or below the second reference speed (step S 104 -No), operation relating to deceleration plan processing by the vehicle control system  1  is complete. In this case, the drive planning device  16  may generate a driving plan for the vehicle  10  so that the vehicle  10  follows other vehicles traveling ahead of it. 
     An example of operating the vehicle  10  that is controlled based on the driving plan described above will now be explained with reference to  FIG. 4 . 
     First, at time T 101 , the vehicle  10  travels at cruising speed on the traffic lane  51  of the road  50 , and the driver determination device  18  determines that the level of active operation by the driver is equal to or above the predetermined reference level (no problem). 
     Next, at time T 102 , the vehicle  10  gives the driver a warning. The vehicle  10  determines that the level of active operation by the driver is lower than the predetermined reference level and the speed of the vehicle  10  is higher than the reference speed. The vehicle  10  travels on the traffic lane  51  while using the first deceleration to decelerate the speed of the vehicle  10  without activating the brake lights  5   a ,  5   b . As the means for achieving the first deceleration, the vehicle  10  may use an engine brake (when the drive unit has an internal combustion engine), a regenerative brake (when the drive unit has an electric motor), or air resistance of the vehicle  10  and friction between the tire and road surface. Since the amount of reduction in speed of the vehicle  10  is on the level of the standard deviation of distribution in the speed of the vehicle traveling on the road  50 , it is within the range of variation in the speed of vehicles traveling on the road  50 . It is therefore assumed that the reduction in the speed of the vehicle  10  by the first deceleration will not interfere with traveling of subsequent vehicles located behind the vehicle  10 . 
     At time T 103 , the vehicle  10  determines that the level of active operation by the driver is lower than the predetermined reference level and the speed of the vehicle  10  is equal to or below the reference speed. The vehicle  10  uses the second deceleration to cause the vehicle  10  to travel on the traffic lane  51  while decelerating. As the means for achieving the second deceleration, the vehicle  10  may use a braking device that reduces the rotational speed of the tires by frictional force, and a regenerative brake (when the vehicle  10  has an electric motor as the drive unit). In the example shown in  FIG. 4 , the vehicle  10  uses a braking device for deceleration, and it therefore travels on the traffic lane  51  while the brake lights  5   a ,  5   b  are activated. 
     Next, at time T 104 , the vehicle  10  determines that the driver is not actively driving. The vehicle  10  activates the emergency flash indicators  4   a  to  4   f  while maintaining a constant speed, and travels on the traffic lane  51  while searching for a target location on the shoulder  53  where the vehicle  10  can stop, within a predetermined range from the current location of the vehicle  10 . 
     Next, at time T 105 , the vehicle  10  activates the turn signals  4   a  to  4   c  indicating that the vehicle  10  will change direction to the left while traveling on the traffic lane  51 , in order to move to the target location on the shoulder  53 . Since the vehicle  10  uses the braking device to decelerate to reach the second deceleration, the brake lights  5   a ,  5   b  are activated and the emergency flash indicators  4   a  to  4   f  are turned off. Alternatively, the vehicle  10  may activate the brake lights  5   a ,  5   b  and turn off the turn signals  4   a  to  4   c.    
     Since the brake lights  5   a ,  5   b  serve to notify drivers of subsequent vehicles that the vehicle  10  is decelerating while the emergency flash indicators  4   a  to  4   f  serve to notify drivers of other surrounding vehicles that the vehicle  10  is in an emergency state, both lights attract attention to the vehicle that has activated them. When the two lights are activated simultaneously, drivers of subsequent vehicles and other surrounding vehicles may not be able to accurately ascertain the state of the vehicle that activated the lamps. The vehicle  10  therefore controls only either the brake lights  5   a ,  5   b  or the emergency flash indicators  4   a  to  4   f  to be activated, so that drivers of subsequent vehicles or other surrounding vehicles are not confused. Depending on the region, drivers of other vehicles may not become confused when two lights are activated. In such cases, the vehicle  10  may activate the brake lights  5   a ,  5   b , while flashing the emergency flash indicators  4   a  to  4   f  Alternatively, the vehicle  10  may activate the brake lights  5   a ,  5   b  and also activate the turn signals  4   a  to  4   c.    
     Next, at time T 106 , the vehicle  10  activates the turn signals  4   a  to  4   c , and enters the shoulder  53  from the traffic lane  51  in which it was traveling, across the lane marking line  55 . Since the turn signal and emergency flash indicator are the same, the emergency flash indicator is turned off during activation of the turn signal. 
     Next, at time T 107 , the vehicle  10  uses the braking device to decelerate, and therefore the vehicle  10  activates the brake lights  5   a ,  5   b  and turns off the emergency flash indicators  4   a  to  4   f.    
     Next, at time T 108 , the vehicle  10  stops at the target location on the shoulder  53 , halts operation of the braking device and activates the emergency flash indicators  4   a  to  4   f.    
     As mentioned above, the vehicle control device  17  of the vehicle  10  decelerates the vehicle  10  with the first deceleration or second deceleration, based on the driving plan generated by the drive planning device  16 . A specific example of a method of decelerating the vehicle  10  by the vehicle control device  17  will now be explained with reference to  FIG. 5 . 
     Since deceleration of the vehicle  10  will often be greatly affected by the gradient of the road on which the vehicle  10  is traveling,  FIG. 6  shows a deceleration method for the first deceleration and a deceleration method for the second deceleration that depend on the gradient of the road. 
     (Deceleration Method for First Deceleration) 
     First, when the vehicle  10  traveling on a level road with a relatively small road gradient, or uphill with a small gradient or downhill with a small gradient, the vehicle control device  17  either stops supply of fuel to the drive unit and uses the engine brake, or uses regenerative braking with the rotary force of the tires for electric motor power generation, as the method for achieving the first deceleration. When deceleration of the vehicle  10  does not reach the first deceleration, the vehicle control device  17  may further increase deceleration by gear downshifting. Alternatively, the method of achieving the first deceleration (and second deceleration) may be air resistance of the vehicle  10  and friction between the tires and road surface, which however is not a method of braking that is controllable by the vehicle control device  17 . 
     When an uphill road on which the vehicle  10  is traveling has a large gradient, the vehicle control device  17  first uses engine braking or regenerative braking as the method of achieving the first deceleration. If the vehicle  10  is decelerated by the large slope of the road so that deceleration of the vehicle  10  increases beyond the first deceleration, then the vehicle control device  17  accelerates the vehicle  10  using the drive unit, controlling the vehicle  10  so that deceleration of the vehicle  10  reaches the first deceleration. The method of achieving the first deceleration (and second deceleration) may also be air resistance of the vehicle  10  and friction between the tires and road surface, which however is not a method of braking that is controllable by the vehicle control device  17 . 
     When a downhill road on which the vehicle  10  is traveling has a large gradient, the vehicle control device  17  uses engine braking or regenerative braking as the method of achieving the first deceleration. Alternatively, the method of achieving the first deceleration (and second deceleration) may be air resistance of the vehicle  10  and friction between the tires and road surface, which however is not a method of braking that is controllable by the vehicle control device  17 . When the level of active operation by the driver is lower than the predetermined reference level and a state where the speed of the vehicle  10  is faster than the reference speed continues for longer than a predetermined time, the drive planning device  16  may generate a second driving plan. The vehicle control device  17  controls the vehicle  10  so that the first deceleration is reached even when the vehicle  10  is traveling on an uphill road with a small gradient or large gradient, or a downhill road with a small gradient or large gradient. 
     (Deceleration Method for Second Deceleration) 
     First, when the vehicle  10  is traveling on a level road with a relatively small road gradient, uphill with a small gradient or downhill with a small gradient, the vehicle control device  17  uses the braking device as the method of achieving the second deceleration. The vehicle control device  17  activates the brake lights  5   a ,  5   b  while the braking device is being operated. The vehicle control device  17  may also use regenerative braking. 
     When an uphill road on which the vehicle  10  is traveling has a large gradient, the vehicle control device  17  then uses engine braking or regenerative braking as the method of achieving the second deceleration. When deceleration of the vehicle  10  does not reach the second deceleration, the vehicle control device  17  may further increase deceleration by gear downshifting. Alternatively, the method of achieving the second deceleration may be air resistance of the vehicle  10  and friction between the tires and road surface, which however is not a controllable method of braking. The vehicle control device  17  may also use a braking device. 
     When a downhill road on which the vehicle  10  is traveling has a large gradient, the vehicle control device  17  uses a braking device as the method of achieving the second deceleration. The vehicle control device  17  activates the brake lights  5   a ,  5   b  while the braking device is being operated. The vehicle control device  17  may also use regenerative braking. The vehicle control device  17  controls the vehicle  10  so that the second deceleration is reached even when the vehicle  10  is traveling on an uphill road with a small gradient or large gradient, or a downhill road with a small gradient or large gradient. 
     As explained above, the vehicle control device determines the level of active operation by the driver and determines the relationship between the speed of the vehicle and a predetermined reference speed. When it has been determined that the level of active operation by the driver is lower than a predetermined reference level and the speed of the vehicle is faster than the reference speed, the vehicle control device generates a first driving plan whereby the first deceleration is used to decelerate the speed of the vehicle without activating the brake light, and when it has been determined that the level of active operation by the driver is lower than the predetermined reference level and the speed of the vehicle is equal to or below the reference speed, it generates a second driving plan whereby a second deceleration that is greater than the first deceleration is used to decelerate the speed of the vehicle. When it has been determined that the level of active operation by the driver is low, therefore, and when the vehicle is traveling at a relatively high speed, the vehicle control device can decelerate the vehicle without activating the brake light until the speed of the vehicle has fallen below the predetermined reference speed, so as not to interfere with traveling of subsequent vehicles. 
     Another example of operation relating to deceleration plan processing by the vehicle control system  1  will now be described with reference to  FIG. 6 . 
     In the example of operation relating to deceleration plan processing by the vehicle control system  1  described above, the vehicle  10  stopped the vehicle on the shoulder adjacent to the traffic lane  51  in which it was traveling, but depending on the terrain it may not be possible to find a shoulder where the vehicle  10  can be stopped. In this case, the vehicle  10  is stopped on the traffic lane in which it is traveling. An operation example in which the vehicle  10  stops on the traffic lane in which it is traveling will now be explained with reference to  FIG. 6 . 
     In the example shown in  FIG. 6 , operation of the vehicle  10  from time T 201  to time T 203  is the same as operation from time T 101  to time T 103  in the operation example described above. At time T 204 , the vehicle  10  searched for, but could not find, a target location on the shoulder  53  where the vehicle  10  could stop within a predetermined range from the current location of the vehicle  10 . The vehicle  10  therefore sets a target location on the traffic lane  51  for deceleration at the second deceleration and stopping. 
     Next, at time T 204 , the vehicle  10  travels on the traffic lane  51  while flashing the emergency flash indicators  4   a  to  4   f , maintaining a constant speed. Next, at time T 205 , the vehicle  10  uses the braking device to decelerate, and therefore activates the brake lights  5   a ,  5   b  and turns off the emergency flash indicators  4   a  to  4   f  Next, at time T 206 , the vehicle  10  stops at the target location on the traffic lane  51 , halts operation of the braking device and activates the emergency flash indicators  4   a  to  4   f.    
     The vehicle control device and computer program for vehicle control and method for controlling vehicle according to the embodiment described above may incorporate appropriate modifications that are still within the gist of the invention. Moreover, the technical scope of the invention is not limited to this embodiment, and includes the invention and its equivalents as laid out in the Claims. 
     For example, in the embodiment described above, the drive planning device generated a driving plan for deceleration of the vehicle  10  when a warning signal was input from the monitoring device, but the drive planning device may instead generate a driving plan for deceleration of the vehicle  10  only after a non-active driving signal has been input from the monitoring device.