Patent Publication Number: US-2018037223-A1

Title: Autonomous driving assistance system, autonomous driving assistance method, and computer program

Description:
TECHNICAL FIELD 
     Related technical fields include autonomous driving assistance systems, methods, and programs that assist a vehicle to travel by using autonomous driving control. 
     BACKGROUND 
     As a vehicle traveling mode other than manual traveling in which a vehicle travels in response to a driving operation by a user, nowadays traveling that uses autonomous driving control is newly proposed in which a vehicle autonomously travels along a road or a preset route without a driving operation by a user. In the autonomous driving control, for example, the present location of a vehicle, a lane where the vehicle travels, and locations of other vehicles around are detected at all times, and vehicle control of a steering wheel, a driving source, a brake, etc. is autonomously performed so that the vehicle can travel along a road or a preset route. Although the traveling that uses the autonomous driving control has the advantage of easing the burden on a user in driving, it is difficult for the autonomous driving control to perform all necessary vehicle operations. For example, one approach may be to perform some difficult vehicle operations, such as an operation necessary to make a lane change, by manual driving by a driver. 
     However, as disclosed in Japanese Patent No. 3094100 (JP 3094100), it is conventional that when a vehicle operation (hereinafter referred to as an override), such as accelerating, braking, or steering performed by a user is detected, the autonomous driving control is basically stopped, and switching to the manual driving is made. 
     SUMMARY 
     According to the technique disclosed in JP 3094100, when the override is detected, regardless of control content of the autonomous driving control being performed and a surrounding environment, all the autonomous driving control being performed is equally stopped, and switching to the manual driving control is made. The problem with JP 3094100 is described with reference to a situation illustrated in  FIG. 11 . In the situation illustrated in  FIG. 11 , lanes  65 - 67  each connect to curves after branching off, and a vehicle  50  travels in the lane  65 , out of the lanes  65  to  67 . It is assumed that a control subject to Which the autonomous driving control is to be applied is the curve connected to the lane  65 , not the curve connected to the lane  66  and the lane  67 . In this situation, according to the Patent Document 1, when the vehicle  50  makes a lane change in response to a steering operation by a user, switching occurs from the autonomous driving control to the manual driving control, so that a user does not feel a sense of discomfort. Conversely, it is assumed that the vehicle  50  travels in either the lane  66  or the lane  67 , out of the lanes  65  to  67 , and that the control subject to which the autonomous driving control is to be applied is the curve connected to the lane  66  and the lane  67 . In this situation, according to JP 3094100, when the vehicle  50  makes a lane change from one of the lane  66  and the lane  67  to the other in response to a steering operation by a user, switching occurs from the autonomous driving control to the manual driving control. As a result, although the control subject to which the autonomous driving control is to be applied is the curve connected to the lane  66  and the lane  67 , a user needs to perform all the vehicle operations, such as accelerating, braking, and steering. This causes a problem in that although there is an opportunity to case the burden on a user in driving a vehicle by performing the control content of the autonomous driving control that controls the speed of the vehicle, out of the control content of the autonomous driving control that causes the vehicle to travel without deviating from a lane and that controls the speed of the vehicle, the opportunity is missed. 
     Exemplary embodiments of the broad inventive principles described herein provide an autonomous driving assistance system, an autonomous driving assistance method, and a computer program that determine, on the basis of presence or absence of detection of an override, the shape of a surrounding road, and content of autonomous driving control being performed, whether to continue or stop the autonomous driving control, thus preventing an increase in the burden on a user in driving a vehicle, associated with stopping the autonomous driving control. 
     Exemplary embodiments provide autonomous driving assistance systems, methods, and programs that acquire a present location of a vehicle, acquire a road shape of a road where the vehicle travels, and set, on the basis of the present location of the vehicle and the road shape of the road where the vehicle travels, control content of first autonomous driving control that causes the vehicle to travel without deviating from a lane and second autonomous driving control that controls a speed of the vehicle in accordance with the road shape. The systems, methods, and programs perform the first autonomous driving control or the second autonomous driving control in compliance with the set control content, detect a steering operation by a driver of the vehicle, and continue or stop the first autonomous driving control or the second autonomous driving control on the basis of the detected steering operation, the present location, and the road shape. 
     The autonomous driving assistance system, the autonomous driving assistance method, and the computer program having the above structure determine, on the basis of presence or absence of detection of the steering operation by the driver, the shape of the surrounding road, and the content of the autonomous driving control being performed, whether to continue or stop the autonomous driving control in the vehicle that travels by using the autonomous driving control. Thus, if the steering operation by the driver is detected, there is no possibility that all the autonomous driving control is equally stopped in the same manner as in the related art. This makes it possible to prevent an increase in the burden on the driver in driving the vehicle, associated with stopping the autonomous driving control. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating the structure of a navigation device according to the present embodiment. 
         FIG. 2  is a flowchart of an autonomous driving start program according to the present embodiment. 
         FIG. 3  is a flowchart of an autonomous driving control change program according to the present embodiment. 
         FIG. 4  is a flowchart of the autonomous driving control change program according to the present embodiment. 
         FIG. 5  illustrates an example case where there is a branch point ahead in the direction of travel of a vehicle and where only part of branching routes has a curve that is a control subject section. 
         FIG. 6  illustrates an example case where there is a branch point ahead in the direction of travel of a vehicle and where only part of branching routes has a curve that is a control subject section. 
         FIG. 7  illustrates an example case where ‘speed management (exit road)’ of autonomous driving control is performed in a vehicle. 
         FIG. 8  illustrates an example situation where, in order to allow a vehicle that travels by using ‘speed management (curve)’ of the autonomous driving control to continue the autonomous driving control, a driver is required to perform a vehicle operation (specifically, a steering operation for making a lane change). 
         FIG. 9  illustrates an example situation where, in order to allow a vehicle that travels by using the ‘speed management (exit road)’ of the autonomous driving control to continue the autonomous driving control, a driver is not required to perform a vehicle operation (specifically, a steering operation for making a lane change). 
         FIG. 10  is a diagram illustrating a modification of the autonomous driving control change program. 
         FIG. 11  illustrates an example case where there is a branch point ahead in the direction of travel of a vehicle and where each branching route has a curve. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     In an embodiment below, a navigation device embodying an autonomous driving assistance system is described in detail with reference to the drawings. First, the general structure of a navigation device  1  according to the present embodiment is described with reference to  FIG. 1 .  FIG. 1  is a block diagram of the navigation device  1  according to the present embodiment. 
     As illustrated in  FIG. 1 , according to the present embodiment, the navigation device  1  includes the following: a present location detecting unit  11  that detects the present location of a vehicle equipped with the navigation device  1 ; a data storage unit  12  that stores various data; a navigation ECU  13  that performs various computations on the basis of input information; an operating portion  14  that receives an operation from a user; a liquid crystal display  15  that displays, to a user, information on a map of an area around the vehicle, a guide route (a route where the vehicle plans to travel) set in the navigation device  1 , etc.; a speaker  16  that outputs voice guidance on route guide; a DVD drive  17  that reads a DVD that is a storage medium; and a communication module  18  that communicates with an information center, such as a probe center or a vehicle information and communication system (registered trade mark: VICS) center. (As used herein, the term “storage medium” is not intended to encompass transitory signals.) The navigation device  1  is connected, via an in-vehicle network, such as CAN, to a vehicle exterior camera  19  and various sensors that are mounted on the vehicle equipped with the navigation device  1 . Further, the navigation device  1  is bidirectionally communicatively connected to a vehicle control ECU  20  that performs various control of the vehicle equipped with the navigation device  1 . Furthermore, the navigation device  1  is connected to various operating buttons  21  that are mounted on the vehicle and that include an autonomous driving start button. 
     The components of the navigation device  1  are described in turn below. The present location detecting unit  11  includes a GPS  22 , a vehicle speed sensor  23 , a steering sensor  24 , and a gyroscope sensor  25 , and is allowed to detect the present location and bearing of the vehicle, the traveling speed of the vehicle, the present time, etc. The vehicle speed sensor  23  is a sensor for detecting the distance traveled by the vehicle and the speed of the vehicle, generates pulses in response to the rotation of driving wheels of the vehicle, and outputs a pulse signal to the navigation ECU  13 . The navigation ECU  13  calculates the rotational speed of the driving wheels and the traveled distance by counting the number of generated pulses. It is noted that the navigation device  1  is not required to include all the four types of sensors and that the navigation device  1  may include only one or a few types of sensors among them. 
     The data storage unit  12  includes a hard disk (not illustrated), serving as an external storage device and a recording medium, and a recording head (not illustrated), serving as a driver for reading a map information DB  31  and prescribed programs recorded on the hard disk and for writing given data on the hard disk. Instead of the hard disk, the data storage unit  12  may include a flash memory, a memory card, an optical disc, such as a CD or DVD, etc. Alternatively, the map information DB  31  may be stored in an external server, and the navigation device  1  may acquire the map information DB  31  via communication. 
     The map information DB  31  is storage means for storing, for example, link data  33  related to roads (links), node data  34  related to node points, finding data  35  used for route finding, facility data related to facilities, map display data used to display a map, intersection data related to intersections, and search data used for location searching. 
     Data recorded as the link data  33  includes the following: data on each link that forms a road to Which the link belongs, namely data indicating the width, slope, cant, and bank of the road, the road surface condition, a merging section, the number of lanes on the road, the location where the number of lanes decreases, the location where the road width decreases, a railroad crossing, etc.; data on a corner, namely data indicating the radius of curvature, an intersection, a T-junction, the entrance and exit of the corner, etc.; data on road attributes, namely data indicating a downhill road, an uphill road, etc.; and data on road type, namely data indicating a local road, such as a national road, a prefectural road, or a narrow street, and a toll road, such as a national highway, an urban highway, an exclusive automobile road, a local toll road, or a toll bridge. 
     Data recorded as the node data  34  includes data on the following: a branch point (including an intersection and a T-junction) of an actual road; coordinates (locations) of node points set at predetermined intervals on each road in accordance with the radius of curvature, etc.; node attributes indicating whether a node corresponds to an intersection, etc.; a connection link number list that lists link numbers of links connecting to the node; an adjacent node number list that lists node numbers of nodes located adjacent to the node across a link; and the height (altitude) of each node point. 
     Data recorded as the finding data  35  includes various data used for route finding that finds a route from a departure point (e.g., the present location of a vehicle) to a set destination. Specifically, cost calculation data used to calculate finding costs, such as a cost (hereinafter referred to as an intersection cost) obtained by quantifying the degree of suitability of a route for an intersection and a cost (hereinafter referred to as a link cost) obtained by quantifying the degree of suitability of a route for a link that forms a road, is stored. 
     On the other hand, the navigation electronic control unit (ECU)  13  is an electronic control unit for performing overall control of the navigation device  1  and has a CPU  41 , serving as a computation device and a control device, and internal storage devices including the following: a RAM  42  that is used as a working memory when the CPU  41  performs various computations and that stores data, such as route data on a found route; a ROM  43  that stores a control program, a later-described autonomous driving start program (refer to  FIG. 2 ), a later-described autonomous driving control change program (refer to  FIG. 3  and  FIG. 4 ), etc.; and a flash memory  44  that stores programs read out from the ROM  43 . It is noted that the navigation ECU  13  structures various means as processing algorithms. For example, control content setting means sets control content of autonomous driving control in accordance with a situation of the vehicle. Control performing means performs the autonomous driving control in compliance with the set control content. Operation detecting means detects a vehicle operation performed by a driver of the vehicle that travels by using the autonomous driving control. Road shape acquiring means acquires the shape of a road where the vehicles travels. Operation requirement determining means determines, on the basis of the road shape and the control content of the autonomous driving control being performed in the vehicle, whether the situation requires a driver to perform the vehicle operation in order to allow the vehicle to continue the autonomous driving control. Control manner changing means continues or stops the autonomous driving control being performed in the vehicle, or changes the control content thereof, on the basis of the results determined by the operation detecting means and the operation requirement determining means. 
     The operating portion  14  is operated, for example, to input a departure location as a travel starting point and a destination as a travel ending point, and has multiple operating switches (not illustrated), such as a key and a button. In response to switch signals that are outputted when the switches are operated, such as being pressed down, the navigation ECU  13  performs control to execute corresponding tasks. The operating portion  14  may have a touch panel provided on the front of the liquid crystal display  15 . Further, the operating portion  14  may have a microphone and a voice recognition device. 
     The liquid crystal display  15  displays, for example, the following: a map image that includes roads; traffic information; an operating guide; an operating menu; a key guide; guidance information corresponding to a guide route (planned travel route); news; weather forecast; the time of day; an email; and a television program. Further, according to the present embodiment, when the traveling that uses the autonomous driving control is started or when the traveling that uses the autonomous driving control is stopped, a related notification is displayed. A HUD or HMD may be used instead of the liquid crystal display  15 . 
     The vehicle can have traveling modes including manual driving traveling in which the vehicle travels in response to a driving operation by a user, and traveling that uses autonomous driving control in which the vehicle autonomously travels on a preset route or along a road without a driving operation by a user. In the autonomous driving control, for example, the present location of the vehicle, a lane where the vehicle travels, and locations of other vehicles around are detected at all times, and the vehicle control ECU  20  autonomously performs vehicle control of a steering wheel, a driving source, a brake, etc. so that the vehicle travels on a preset route or along a road. According to the present embodiment, during the traveling that uses the autonomous driving control, the vehicle travels in the same lane without making a lane change nor making a right or left turn unless a user performs a vehicle operation for a lane change or for a right or left turn. 
     According to the present embodiment, in particular, five kinds of autonomous driving control described below are performed, 
     (1) ‘Constant speed traveling’ . . . The vehicle travels in the same lane at a preset speed (e.g., 90% of the speed limit of the road where the vehicle travels).
 
(2) ‘Tracking traveling’ . . . The vehicle travels in the same lane while maintaining a predetermined distance (e.g., 10 m) from a vehicle ahead as far as within a set speed (e.g., 90% of the speed limit of the road where the vehicle travels).
 
(3) ‘Speed management (curve)’ . . . When there is a curve ahead in the direction of travel, the vehicle decelerates to a speed corresponding to the radius of curvature of the curve before entering the curve.
 
(4) ‘Speed management (exit road)’ . . . The vehicle is limited in acceleration when traveling in a deceleration lane (exit road) provided on a highway or the like.
 
(5) ‘Speed management (tollgate, temporary stop, traffic signal)’ . . . When there is a tollgate, a temporary stop, or a traffic signal ahead in the direction of travel, the vehicle decelerates to a speed (e.g., 20 km/h) that allows the vehicle to stop, without putting strain on an occupant, before reaching the tollgate, the temporary stop (road sign), or the traffic signal. Further, in parallel with the above control (1) to (5), control (6) that causes the vehicle to travel almost in the middle of a lane without deviating from the lane lane keeping assist) is performed.
 
     The autonomous driving control (1) to (6) described above may be performed in any road section, and alternatively, may be performed only while the vehicle travels on a highway that has a gate (regardless of whether it is manned, unmanned, tolled, or untolled) at the border with another road connected thereto. It is noted that the autonomous driving control is not always performed when the vehicle travels in a section (hereinafter referred to as an autonomous driving section) where autonomous driving is allowed. The autonomous driving control is performed only when a user chooses to perform the autonomous driving control and when it is determined that the vehicle is allowed to travel by using the autonomous driving control. The vehicle is not allowed to travel by using the autonomous driving control, for example, when weather is bad or when pavement markings have faded away or gotten so light that the camera cannot recognize them. 
     Further, when a specific vehicle operation (hereinafter referred to as an override), such as accelerating, braking, or steering, performed by a user is detected while the vehicle travels by using the autonomous driving control, the autonomous driving control is stopped in some cases. For example, when a braking operation by a user is detected, the above controls (1) to (5) are stopped. Further, when a steering operation by a user is detected, the above controls (1) to (5) are basically continued, hut the control (6) is temporarily stopped until the operation is finished. However, according to the present embodiment, as described later, when the shape of the surrounding road or the control content of the autonomous driving control being performed satisfies a predetermined condition, the controls (1) to (5) may be stopped upon detection of a steering operation by a user. 
     The speaker  16  outputs, on the basis of an instruction from the navigation ECU  13 , voice guidance for traveling along a guide route and traffic information guidance. Further, according to the present embodiment, when the traveling that uses the autonomous driving control is started or when the traveling that uses the autonomous driving control is stopped, related voice guidance is outputted. 
     The DVD drive  17  is a drive capable of reading data recorded on a recording medium such as a DVD or CD. On the basis of read data, the DVD drive  17  plays back music and video, updates the map information DB  31 , etc. The DVD drive  17  may be replaced with a card slot for reading and writing a memory card. 
     The communication module  18  is a communication device for receiving traffic information, probe information, weather information, etc., transmitted from a traffic information center, such as a VICS center or a probe center. For example, the communication module  18  corresponds to a mobile phone or DCM. Further, a vehicle-to-vehicle communication device for performing vehicle-to-vehicle communications and a vehicle to roadside communication device for performing vehicle-to-roadside communications are also included. 
     The vehicle exterior camera  19  is, for example, a camera with a solid-state image sensing device, such as a CCD, and is installed on the upper part of the front bumper of the vehicle with its optical axis angled downward by a predetermined degree relative to the horizontal. When the vehicle travels in the autonomous driving section, the vehicle exterior camera  19  captures an image of the area ahead of the vehicle in the direction of travel. The vehicle control ECU  20  processes the captured image to detect pavement markings on the road where the vehicle travels, other vehicles around, etc., and performs the autonomous driving control of the vehicle on the basis of the detected results. Instead of on the front of the vehicle, the vehicle exterior camera  19  may be installed on the back or side. As means for detecting other vehicles, a sensor, such as a millimeter-wave radar, vehicle-to-vehicle communications, or vehicle-to-roadside communications may be used instead of a camera. As means for detecting weather in surrounding areas, an illuminance sensor or a precipitation sensor may be installed. 
     The vehicle control ECU  20  is an electronic control unit for controlling the vehicle equipped with the navigation device  1 . The vehicle control ECU  20  is connected to drive systems of the vehicle including a steering wheel, a brake, and an accelerator. According to the present embodiment, in particular, after the autonomous driving control is started in the vehicle, the vehicle control ECU  20  performs the autonomous driving control of the vehicle by controlling the drive systems. Further, when a user makes the override during the autonomous driving control, the vehicle control ECU  20  detects that the override is made. 
     After the start of travel, the navigation ECU  13  transmits an instruction signal related to the autonomous driving control to the vehicle control ECU  20  via CAN. In response to the received instruction signal, the vehicle control ECU  20  performs the autonomous driving control after the start of travel. The instruction signal contains information including the control content of the autonomous driving control of the vehicle (e.g., any of the above (1) to (6)) and an instruction for starting, stopping, or changing control. Instead of the navigation ECU  13 , the vehicle control ECU  20  may be structured to set the control content of the autonomous driving control. In this case, the vehicle control ECU  20  is structured to acquire, from the navigation device  1 , information necessary for setting the autonomous driving control, such as a planned travel route (guide route), vehicle conditions, or map information on surrounding areas. 
     Next, an autonomous driving start program executed by the CPU  41  of the navigation device  1  having the above structure according to the present embodiment is described with reference to  FIG. 2 .  FIG. 2  is a flowchart of the autonomous driving start program according to the present embodiment. The autonomous driving start program is executed after an ACC power of the vehicle is turned on, and starts the autonomous driving control of the vehicle when a predetermined condition is met. The programs illustrated in the flowcharts of  FIG. 2  to  FIG. 4  are stored in the RAM  42  or the ROM  43  of the navigation device  1  and are executed by the CPU  41 . 
     In the autonomous driving start program, the CPU  41  first acquires, in step (hereinafter abbreviated as S)  1 , vehicle information related to its own vehicle. Specifically, the CPU  41  acquires the present location of the vehicle detected by the present location detecting unit  11  and the present vehicle speed of the vehicle detected by the vehicle speed sensor  23 . It is preferable that the present location of the vehicle be precisely identified by high-accuracy location technology. 
     Then, in S 2 , the CPU  41  acquires the shape of a road ahead in the direction of travel of the vehicle and the surrounding environment, for example, by reading information from the map information DB  31 , by acquiring the result detected by the vehicle exterior camera  19  or other sensors, or by communicating with an external server, such as a VICS center or a probe center. As the shape of the road ahead in the direction of travel of the vehicle, the CPU  41  acquires, for example, information on whether there is a curve section, a tollgate, a temporary stop, a traffic signal, or a deceleration lane on a route within one kilometer from the present location of the vehicle along the road (a guide route, if the guide route is already set in the navigation device  1 ). When there is a curve, the CPU  41  also acquires the radius of curvature of the curve and a start point where the curve starts. As the surrounding environment, the CPU  41  acquires, for example, the locations of other vehicles around its own vehicle. 
     Then, in S 3 , the CPU  41  determines, on the basis of the vehicle information acquired in S 1  and the road shape acquired in S 2 , whether there is any of a curve, a tollgate, a temporary stop (road sign), and a traffic signal that are each a control subject section ahead in the direction of travel of the vehicle. The control subject section is a section where the vehicle is subjectable to special control (e.g., deceleration control), other than the constant speed traveling and the tracking traveling, of the autonomous driving control when traveling there. 
     Then, if the CPU  41  determines that there is any of a curve, a tollgate, a temporary stop (road sign), and a traffic signal ahead in the direction of travel of the vehicle (YES in S 3 ), the program proceeds to S 4 . In contrast, if the CPU  41  determines that there is not any of a curve, a tollgate, a temporary stop (road sign), and a traffic signal ahead in the direction of travel of the vehicle (NO in S 3 ), the program proceeds to S 7 . 
     If determining that there is a curve ahead in the direction of travel, in S 4 , the CPU  41  calculates, on the basis of the present vehicle speed of the vehicle and a distance to the start point of the curve, a location (deceleration start location) where the vehicle needs to start decelerating so that the vehicle can decelerate to a speed corresponding to the radius of curvature of the curve before entering the curve. Likewise, if determining that there is a tollgate, a temporary stop (road sign), or a traffic signal ahead in the direction of travel, the CPU  41  calculates, on the basis of the present vehicle speed of the vehicle and a distance to the tollgate, the temporary stop (road sign), or the traffic signal, a location (deceleration start location) where the vehicle needs to start decelerating so that the vehicle can decelerate to a speed (e.g., 20 km/h) that allows the vehicle to stop, without putting strain on an occupant, before reaching the tollgate, the temporary stop (road sign), or the traffic signal. 
     Then, in S 5 , the CPU  41  determines whether the vehicle passes the deceleration start location calculated in S 4 . 
     If the CPU  41  determines that the vehicle passes the deceleration start location calculated in S 4  (YES in S 5 ), the program proceeds to S 6 . In contrast, if the CPU  41  determines that the vehicle does not pass the deceleration start location calculated in S 4  (NO in S 5 ), the program returns to S 1 . 
     If determining that there is a curve ahead in the direction of travel, in S 6 , the CPU  41  instructs the vehicle control ECU  20  to start the ‘speed management (curve)’. In contrast, if determining that there is a tollgate, a temporary stop (road sign), or a traffic signal ahead in the direction of travel, the CPU  41  instructs the vehicle control ECU  20  to start the ‘speed management (tollgate, temporary stop, traffic signal)’. As a result, the vehicle control ECU  20  that receives the instruction signal starts processing related to the autonomous driving control, and the vehicle starts using the autonomous driving control to travel. The ‘speed management (curve)’ is control that allows the vehicle to decelerate to the speed corresponding to the radius of curvature of the curve before entering the curve. The ‘speed management (tollgate, temporary stop, traffic signal)’ is control that allows the vehicle to decelerate to the speed (e.g., 20 km/h) that allows the vehicle to stop, without putting strain on an occupant, before reaching the tollgate, the temporary stop (road sign), or the traffic signal. In the autonomous driving control, control that causes the vehicle to travel almost in the middle of a lane without deviating from the lane is performed in parallel with the above control. 
     It is noted that the autonomous driving control is not always performed in S 6  when it is determined in S 5  that the determination condition is met. The autonomous driving control is performed in S 6  only when a user chooses to perform the autonomous driving control by operating the operating button  21 , such as the autonomous driving start button, mounted on the vehicle and when it is determined that the vehicle is allowed to travel by using the autonomous driving control. The autonomous driving control is not performed, for example, when weather is bad or when pavement markings have faded away or gotten so light that the camera cannot recognize them. 
     In contrast, in S 7 , the CPU  41  determines, on the basis of the vehicle information acquired in S 1  and the road shape acquired in S 2 , whether the vehicle moves into a deceleration lane (exit road) that is the control subject section. The deceleration lane is provided, for example, at an interchange or junction of a highway to allow vehicles to exit main lanes. Further, the deceleration lane is provided to allow vehicles to enter a rest area or a parking area. 
     If the CPU  41  determines that the vehicle moves into the deceleration lane (exit road) (YES in S 7 ), the program proceeds to S 8 . In contrast, if the CPU  41  determines that the vehicle does not move into the deceleration lane (exit road) (NO in S 7 ), the program proceeds to S 9 . 
     In S 8 , the CPU  41  instructs the vehicle control ECU  20  to start the ‘speed management (exit road)’. As a result, the vehicle control ECU  20  that receives the instruction signal starts processing related to the autonomous driving control, and the vehicle starts using the autonomous driving control to travel. The ‘speed management (exit road)’ is control that does not allow the vehicle to accelerate even when the vehicle speed of the vehicle is slower than a set speed (e.g., 90% of the speed limit of the road where the vehicle travels). In the autonomous driving control, control that causes the vehicle to travel almost in the middle of a lane without deviating from the lane is performed in parallel with the above control. 
     It is noted that the autonomous driving control is not always performed in S 8  when it is determined in S 7  that the determination condition is met. The autonomous driving control is performed in S 8  only when a user chooses to perform the autonomous driving control by operating the operating button  21 , such as the autonomous driving start button, mounted on the vehicle and when it is determined that the vehicle is allowed to travel by using the autonomous driving control. The autonomous driving control is not performed, for example, when weather is bad or when pavement markings have faded away or gotten so light that the camera cannot recognize them. 
     In contrast, in S 9 , the CPU  41  determines, on the basis of the vehicle information acquired in S 1  and the surrounding environment, whether there is another vehicle ahead and whether the present vehicle speed of the vehicle is slower than a set speed (e.g., 90% of the speed limit of the road where the vehicle travels). 
     If the CPU  41  determines that there is the other vehicle ahead and that the present vehicle speed of the vehicle is slower than the set speed (YES in S 9 ), the program proceeds to S 10 . In contrast, if the CPU  41  determines that there is no vehicle ahead or that the present vehicle speed of the vehicle is faster than the set speed (NO in S 9 ), the program proceeds to S 11 . 
     In S 10 , the CPU  41  instructs the vehicle control ECU  20  to start the ‘tracking traveling’. As a result, the vehicle control ECU  20  that receives the instruction signal starts processing related to the autonomous driving control, and the vehicle starts using the autonomous driving control to travel. The ‘tracking traveling’ is control that allows the vehicle to travel while maintaining a predetermined distance (e.g., 10 m) from another vehicle ahead as far as within a set speed (e.g., 90% of the speed limit of the road where the vehicle travels). In the autonomous driving control, control that causes the vehicle to travel almost in the middle of a lane without deviating from the lane is performed in parallel with the above control. 
     In contrast, in S 11 , the CPU  41  instructs the vehicle control ECU  20  to start the ‘constant speed traveling’. As a result, the vehicle control ECU  20  that receives the instruction signal starts processing related to the autonomous driving control, and the vehicle starts using the autonomous driving control to travel. The ‘constant speed traveling’ is control that allows the vehicle to travel at a preset speed (e.g., 90% of the speed limit of the road where the vehicle travels). In the autonomous driving control, control that causes the vehicle to travel almost in the middle of a lane without deviating from the lane is performed in parallel with the above control. 
     It is noted that the autonomous driving control is not always performed in S 10  or S 11  when it is determined in S 9  that the determination condition is met or not met. The autonomous driving control is performed in S 10  or S 11  only when a user chooses to perform the autonomous driving control by operating the operating button  21 , such as the autonomous driving start button, mounted on the vehicle and when it is determined that the vehicle is allowed to travel by using the autonomous driving control. The autonomous driving control is not performed, for example, when weather is bad or when pavement markings have faded away or gotten so light that the camera cannot recognize them. 
     Next, the autonomous driving control change program executed by the CPU  41  of the navigation device  1  having the above structure according to the present embodiment is described with reference to  FIG. 3  and  FIG. 4 .  FIG. 3  and  FIG. 4  are flowcharts of the autonomous driving control change program according to the present embodiment. The autonomous driving control change program is executed when the vehicle travels by using the autonomous driving control. On the basis of presence or absence of detection of the override and the shape of the surrounding road, the autonomous driving control change program continues or stops the autonomous driving control, or changes the control content thereof. 
     First, in S 21 , the CPU  41  acquires the present location of the vehicle. It is preferable that the present location of the vehicle be precisely identified by high-accuracy location technology and that which lane the vehicle travels in be identified when the vehicle travels on a multiple lane road. 
     Then, in S 22 , the CPU  41  acquires the shape of the road ahead in the direction of travel of the vehicle, for example, by reading information from the map information DB  31 , by acquiring the result detected by the vehicle exterior camera  19  or other sensors, or by communicating with an external server, such as a VICS center or a probe center. In particular, when there is a branch point ahead in the direction of travel of the vehicle, the CPU  41  also acquires information on lane demarcation, road connection for each lane, and a road shape of each route after the branch point. For example, when the vehicle  50  travels in a road section as illustrated in  FIG. 5 , the CPU  41  acquires information that the road has three lanes  51  to  53  and branches, at a branch point ahead in the direction of travel, into different routes, one of which has the lane  51 , and the other has the lanes  52  and  53 . Further, the CPU  41  acquires information that the route connected to the lane  51  is curved after the branch point and that the route connected to the lanes  52  and  53  remains straight after the branch point. 
     Then, in S 23 , the CPU  41  acquires the control state of the autonomous driving control by communicating with the vehicle control ECU  20  via CAN and determines whether the vehicle is performing the ‘speed management (curve)’ of the autonomous driving control. 
     If the CPU  41  determines that the vehicle is performing the ‘speed management (curve)’ of the autonomous driving control (YES in S 23 ), the program proceeds to S 24 . In contrast, if the CPU  41  determines that the vehicle is not performing the ‘speed management (curve)’ of the autonomous driving control (NO in S 23 ), the program proceeds to S 27 . 
     In S 24 , the CPU  41  determines, on the basis of the road shape acquired in S 22 , whether there is a branch point ahead in the direction of travel of the vehicle and whether only part of branching routes has a curve that is the control subject section. For example, when the road shape is like what is illustrated in  FIG. 5  or  FIG. 6 , the CPU  41  determines in S 24  that only part of the branching routes has a curve that is the control subject section. In the example illustrated in  FIG. 5 , the lane  51  as part of the multiple lanes  51  to  53  that form the road connects to a curved road that branches off from the other lanes  52  and  53 . On the other hand, in the example illustrated in  FIG. 6 , a new lane  54  is added, and the added lane  54  branches of from other lanes  55  and  56  and connects to a curved road. 
     If the CPU  41  determines that only part of the branching routes has a curve that is the control subject section (YES in S 24 ), the program proceeds to S 25 . In contrast, if the CPU  41  determines that there is no branch point ahead in the direction of travel or determines that although there is a branch point, each branching route has a curve that is the control subject section (NO in S 24 ), the program proceeds to S 26 . 
     In S 25 , the CPU  41  estimates that the override, in particular, a steering operation for making a lane change influences the performance of the autonomous driving control presently being performed. For example, in the situation illustrated in  FIG. 5 , when the vehicle  50  makes a lane change to the right, so that a lane where the vehicle  50  travels changes from the lane  51  to the lane  52 , the vehicle  50  will not travel in a curve section later. Therefore, the ‘speed management (curve)’ of the autonomous driving control needs to be stopped when being performed for the curve ahead. On the other hand, in the situation illustrated in  FIG. 6 , when the vehicle  50  keeps in the lane  55  or the lane  56  without making a lane change to the lane  54 , the vehicle  50  will not travel in a curve section later. Therefore, the ‘speed management (curve)’ of autonomous driving control needs to be stopped when being performed for the curve ahead. 
     In contrast, in S 26 , the CPU  41  estimates that the override, in particular, a steering operation for making a lane change does not influence the performance of the autonomous driving control presently being performed. That is, since the vehicle will travel in a curved section later whichever lane the vehicle travels in, no problem occurs when the ‘speed management (curve)’ of the autonomous driving control is continuously performed for the curve ahead, regardless of whether the vehicle makes a lane change. 
     In S 27 , the CPU  41  acquires the control state of the autonomous driving control by communicating with the vehicle control ECU  20  via CAN and determines whether the vehicle is performing the ‘speed management (exit road)’ of the autonomous driving control. 
     If the CPU  41  determines that the vehicle is performing the ‘speed management (exit road)’ of the autonomous driving control (YES in S 27 ), the program proceeds to S 28 . In contrast, if the CPU  41  determines that the vehicle is not performing the ‘speed management (exit road)’ of the autonomous driving control either, i.e., determines that the vehicle is performing any of the ‘constant speed traveling’, the ‘tracking traveling’, and the ‘speed management (tollgate, temporary stop, traffic signal)’ of the autonomous driving control (NO in S 27 ), the program proceeds to S 29 . 
     In S 28 , the CPU  41  estimates that the override, in particular, a steering operation for making a lane change influences the performance of the autonomous driving control presently being performed. For example, as illustrated in  FIG. 7 , when the vehicle  50  travels in a lane  61  that is a deceleration lane, the ‘speed management (exit road)’ of the autonomous driving control is basically performed. However, when the vehicle  50  makes a lane change and moves into a lane  62  or a lane  63  that is not a deceleration lane, the vehicle  50  will not travel in a deceleration lane later. Therefore, the ‘speed management (exit road)’ of the autonomous driving control needs to be stopped when being performed for a deceleration lane. 
     In contrast, in S 29 , the CPU  41  estimates that the override, in particular, a steering operation for making a lane change does not influence the performance of the autonomous driving control presently being performed. For example, when the ‘constant speed traveling’ or the ‘tracking traveling’ is being performed, continuously performing the autonomous driving control causes no problem whichever lane the vehicle moves into. Further, when the ‘speed management (tollgate, temporary stop, traffic signal)’ is being performed, the vehicle will reach a tollgate, a temporary stop, or a traffic signal later whichever lane the vehicle travels in. In this case, therefore, continuously performing the ‘speed management (tollgate, temporary stop, traffic signal)’ of the autonomous driving control for the tollgate, the temporary stop, or the traffic signal ahead causes no problem, regardless of whether the vehicle makes a lane change. 
     Then, in S 30 , the CPU  41  determines, on the basis of the result estimated in S 25 , S 26 , S 28 , or S 29 , whether the override, in particular, a steering operation for making a lane change influences the performance of the autonomous driving control presently being performed. 
     If the CPU  41  determines that a steering operation for making a lane change influences the performance of the autonomous driving control presently being performed (YES in S 30 ), the program proceeds to S 32 . In contrast, if the CPU  41  determines that a steering operation for making a lane change does not influence the performance of the autonomous driving control presently being performed (NO in S 30 ), the program proceeds to S 31 . In S 31 , regardless of whether a steering operation for making a lane change is made, the CPU  41  continues the autonomous driving control presently being performed. 
     In contrast, in S 32 , the CPU  41  acquires the control state of the autonomous driving control by communicating with the vehicle control ECU  20  via CAN and determines whether the vehicle is performing the ‘speed management (curve)’ of the autonomous driving control. 
     If the CPU  41  determines that the vehicle is performing the ‘speed management (curve)’ of the autonomous driving control (YES in S 32 ), the program proceeds to S 33 . In contrast, if the CPU  41  determines that the vehicle is not performing the ‘speed management (curve)’ of the autonomous driving control (NO in S 32 ), the program proceeds to S 37 . 
     In S 33 , the CPU  41  determines, on the basis of the present location of the vehicle acquired in S 21 , the road shape acquired in S 22 , and an override operation detected by the vehicle control ECU  20 , whether a steering operation for making a lane change is performed and whether only a lane different from the lane where the vehicle travels until the operation is performed connects to a curve. Here, “the situation where only a lane different from the lane where the vehicle travels connects to a curve” refers to, for example, a situation illustrated in  FIG. 8 , where in order to allow the vehicle that travels by using the ‘speed management (curve)’ of the autonomous driving control to continue the autonomous driving control, a driver is required to perform a vehicle operation (specifically, a steering operation for making a lane change) so as to move into a lane connecting to a curve. 
     In a case where the CPU  41  determines that a steering operation for making a lane change is performed and that only a lane different from the lane where the vehicle travels until the operation is performed connects to a curve (YES in S 33 ), the autonomous driving control being performed is continued (S 34 ) because this case occurs when a driver performs a vehicle operation in a situation where the driver is required to perform the vehicle operation in order to allow the vehicle that travels by using the autonomous driving control to continue the autonomous driving control. In contrast, if a steering operation for making a lane change is not performed, or the lane where the vehicle travels until the operation is performed connects to a curve (S 33  in NO), the program proceeds to S 35 . 
     In S 35 , the CPU  41  determines, on the basis of the present location of the vehicle acquired in S 21 , the road shape acquired in S 22 , and the override operation detected by the vehicle control ECU  20 , whether a steering operation for making a lane change is not performed and whether the lane where the vehicle travels connects to a curve. Here, “the situation where the lane where the vehicle travels connects to a curve” refers to, for example, a situation illustrated in  FIG. 9 , where in order to allow the vehicle that travels by using the ‘speed management (curve)’ of the autonomous driving control to continue the autonomous driving control, a driver is required to keep in the present lane without performing a vehicle operation (specifically, a steering operation for making a lane change). 
     In a case where the CPU  41  determines that a steering operation for making a lane change is not performed and that the lane where the vehicle travels connects to a curve (YES in S 35 ), the autonomous driving control being performed is continued (S 34 ) because this case occurs when a driver does not perform a vehicle operation in a situation where the driver is not required to perform the vehicle operation in order to allow the vehicle that travels by using the autonomous driving control to continue the autonomous driving control. 
     In contrast, in a case where the CPU  41  determines that a steering operation for making a lane change is not performed and that only a lane different from the lane where the vehicle travels connects to a curve (NO in S 35 ), the vehicle control ECU  20  is instructed to stop the autonomous driving control being performed (S 36 ) because this case occurs when a driver does not perform the vehicle operation in a situation (for example, in the situation illustrated in  FIG. 8 ) where the driver is required to perform the vehicle operation in order to allow the vehicle that travels by using the autonomous driving control to continue the autonomous driving control. 
     Likewise, in a case where the CPU  41  determines that a steering operation for making a lane change is performed and that the lane where the vehicle travels until the operation is performed connects to a curve (NO in S 35 ), the vehicle control ECU  20  is instructed to stop the autonomous driving control being performed (S 36 ) because this case occurs when a driver performs a vehicle operation in a situation (for example, in the situation illustrated in  FIG. 9 ) where the driver is not required to perform the vehicle operation in order to allow the vehicle that travels by using the autonomous driving control to continue the autonomous driving control. This prevents the ‘speed management (curve)’ of the autonomous driving control from being continued when the vehicle is expected not to travel in a curve later. 
     Alternatively, in S 36 , the control content may be changed from the ‘speed management (curve)’ to another of the autonomous driving control (e.g., the ‘constant speed traveling’ or the ‘tracking traveling’) without stopping the autonomous driving control. Further, control (e.g., lane keeping assist) that causes the vehicle to travel almost in the middle of a lane without deviating from the lane may be continued when the ‘speed management (curve)’ is stopped. 
     In S 37 , the CPU  41  acquires the control state of the autonomous driving control by communicating with the vehicle control ECU  20  via CAN and determines whether the vehicle is performing the ‘speed management (exit road)’ of the autonomous driving control. 
     If the CPU  41  determines that the vehicle is performing the ‘speed management (exit road)’ of the autonomous driving control (YES in S 37 ), the program proceeds to S 38 . Here, the situation where the ‘speed management (exit road)’ of the autonomous driving control is being performed refers to, for example, the situation illustrated in  FIG. 7 , where in order to allow the vehicle that travels by using the ‘speed management (curve)’ of the autonomous driving control to continue the autonomous driving control, a driver is required to keep in the present lane without performing a vehicle operation (specifically, a steering operation for making a lane change). 
     In contrast, if the CPU  41  determines that the vehicle is not performing the ‘speed management (exit road)’ of the autonomous driving control either, i.e., determines that the vehicle is performing any of the ‘constant speed traveling’, the ‘tracking traveling’, and the ‘speed management (tollgate, temporary stop, traffic signal)’ of the autonomous driving control (NO in S 37 ), the program proceeds to S 31 . In S 31 , regardless of whether a steering operation for making a lane change is made, the CPU  41  continues the autonomous driving control presently being performed. 
     In S 38 , the CPU  41  determines, on the basis of an override operation detected by the vehicle control ECU  20 , whether the override, in particular, a steering operation for making a lane change is made. 
     In a case where the CPU  41  determines that a steering operation for making a lane change is performed (YES in S 38 ), the vehicle control ECU  20  is instructed to change the autonomous driving control to be performed to the ‘constant speed traveling’ (S 39 ) because this case occurs when a driver performs a vehicle operation in a situation (for example, in the situation illustrated in  FIG. 7 ) where the driver is not required to perform the vehicle operation in order to allow the vehicle that travels by using the autonomous driving control to continue the autonomous driving control. This prevents the ‘speed management (exit road)’ of the autonomous driving control from being continued after the vehicle returns to a main lane from a deceleration lane (exit road). Alternatively, in S 39 , the autonomous driving control may be stopped. 
     In contrast, in a case where the CPU  41  determines that a steering operation for making a lane change is not performed (NO in S 38 ), the autonomous driving control being performed is continued (S 40 ) because this case occurs when a driver does not perform a vehicle operation in a situation (for example, in the situation illustrated in  FIG. 7 ) where the driver is not required to perform the vehicle operation in order to allow the vehicle that travels by using the autonomous driving control to continue the autonomous driving control. 
     As described in detail above, the navigation device  1  according to the present embodiment, an autonomous driving assistance method by the navigation device  1 , and a computer program executed in the navigation device  1  performs autonomous driving control by setting control content of the autonomous driving control in accordance with a situation of a vehicle (S 3  to S 11 ) and determines, on the basis of the shape of a road where the vehicle travels and the control content of the autonomous driving control being performed in the vehicle, whether the situation requires a driver to perform a vehicle operation in order to allow the vehicle to continue the autonomous driving control, and continues or stops the control content of the autonomous driving control being performed in the vehicle, or changes the control content thereof, on the basis of the determined result and presence or absence of the vehicle operation by a driver (S 31 , S 34 , S 36 , S 39 , S 40 ). Thus, if the vehicle operation by a driver is detected, there is no possibility that all the autonomous driving control is equally stopped in the same manner as in the related art. This makes it possible to continue the autonomous driving control, for example, in a situation where the autonomous driving control does not need to be stopped, thus preventing an increase in the burden on a driver in driving the vehicle, associated with stopping the autonomous driving control. Further, in a situation where the autonomous driving control needs to be stopped, this makes it possible to continue the autonomous driving control by changing the control content thereof, thus preventing an increase in the burden on a driver in driving the vehicle, associated with stopping the autonomous driving control. 
     It is noted that various improvements and modifications are possible without departing from the spirit of the inventive principles. 
     For example, the autonomous driving control change program ( FIG. 3  and  FIG. 4 ) executed by the CPU  41  of the navigation device  1  according to the present embodiment may be structured as described below.  FIG. 10  illustrates a modification of the autonomous driving assistance program according to the present embodiment. 
     Since procedures in S 50  to S 54  are the same as the procedures in S 30  to S 34 , their description is omitted. Further, the program proceeds to S 50  after the procedures in S 21  to S 29  are executed. 
     First, in S 55 , the CPU  41  determines, on the basis of the present location of the vehicle acquired in S 21 , the road shape acquired in S 22 , and an override operation detected by the vehicle control ECU  20 . Whether a steering operation for making a lane change is not performed and whether only a lane where the vehicle travels connects to a curve. Here, “the situation where only the lane where the vehicle travels connects to a curve” refers to, for example, the situation illustrated in  FIG. 9 , where in order to allow the vehicle that travels by using the ‘speed management (curve)’ of the autonomous driving control to continue the autonomous driving control, a driver is required to keep in the present lane to travel without performing a vehicle operation (specifically, a steering operation for making a lane change). 
     In a case where the CPU  41  determines that a steering operation for making a lane change is not performed and that only the lane where the vehicle travels connects to a curve (YES in S 55 ), the autonomous driving control being performed is continued (S 54 ) because this case occurs when a driver does not perform a vehicle operation in a situation where the driver is not required to perform the vehicle operation in order to allow the vehicle that travels by using the autonomous driving control to continue the autonomous driving control. 
     In contrast, if the CPU  41  determines that a steering operation for making a lane change is not performed and that a lane different from the lane where the vehicle travels also connects to a curve or the lane where the vehicle travels does not connect to a curve (NO in S 55 ), the program proceeds to S 56 . 
     In S 56 , the CPU  41  determines, on the basis of the present location of the vehicle acquired in S 21  and the road shape acquired in S 22 , whether branching lanes each connect to curves and whether the vehicle travels in a lane different from a lane connecting to a curve that is the control subject for the ‘speed management (curve)’. Here, “the vehicle travels in a lane different from a lane connecting to a curve that is the control subject for the ‘speed management (curve)’” refers to, for example, a situation illustrated in  FIG. 11 , where lanes  65  to  67  each connect to curves after branching off and where the vehicle  50  travels in the lane  65  connecting to a curve that is not the control subject for the ‘speed management (curve)’ of the autonomous driving control, without traveling in the lanes  66  and  67  connecting to a curve that is the control subject for the ‘speed management (curve)’ of the autonomous driving control. 
     If the CPU  41  determines that the branching lanes each connect to curves and that the vehicle travels in a lane different from a lane connecting to a curve that is the control subject for the ‘speed management (curve)’ (YES in S 56 ), the control content of the ‘speed management (curve)’ is changed (S 57 ). Specifically, when a distance to the deceleration start location for the curve connected to the lane where the vehicle travels is less than a distance to the deceleration start location for the curve that is the control subject for the ‘speed management (curve)’, the deceleration rate is increased in accordance with the deceleration start location for the curve connected to the lane where the vehicle travels. In contrast, when the distance to the deceleration start location for the curve connected to the lane where the vehicle travels is larger than the distance to the deceleration start location for the curve that is the control subject for the ‘speed management (curve)’, the deceleration rate is reduced in accordance with the deceleration start location for the curve connected to the lane where the vehicle travels. 
     In contrast, a case where the CPU  41  determines that none of the branching lanes connects to a curve (NO in S 56 ) occurs when a driver does not perform a vehicle operation in a situation (for example, in the situation illustrated in  FIG. 8 ) where the driver is required to perform the vehicle operation in order to allow the vehicle that travels by using the autonomous driving control to continue the autonomous driving control, or occurs when a driver performs a vehicle operation in a situation (for example, in the situation illustrated in  FIG. 9 ) where the driver is not required to perform the vehicle operation in order to allow the vehicle that travels by using the autonomous driving control to continue the autonomous driving control. Therefore, the vehicle control ECU  20  is instructed to stop the autonomous driving control being performed (S 58 ). This prevents the ‘speed management (curve)’ of the autonomous driving control from being continued when the vehicle is expected not to travel in a curve later. 
     If the CPU  41  determines that the branching lanes each connect to curves and that the vehicle travels in a lane connecting to a curve that is the control subject for the ‘speed management (curve)’, the presently performed ‘speed management (curve)’ control is continued. 
     Since subsequent procedures in S 59  to S 62  are the same as the procedures in S 37  to S 40 , their description is omitted. 
     Although, according to the present embodiment, any of (1) to (6) described above is performed as the autonomous driving control, control other than (1) to (6) may be performed. For example, acceleration control, stop control, or control related to a right or left turn or a lane change may be performed. 
     Although, according to the present embodiment, a determination whether to continue or stop the autonomous driving control being performed in the vehicle, or change the control content thereof is made on the basis of whether, the override, in particular, the steering operation for making a lane change is made, the determination may be made on the basis of an override other than a steering operation for making a lane change. For example, the determination may be made on the basis of an accelerator operation or a brake operation. 
     Although, according to present embodiment, the navigation device  1  executes the autonomous driving start program (refer to  FIG. 2 ) and the autonomous driving control change program (refer to  FIG. 3  and  FIG. 4 ), the vehicle control ECU  20  may execute them instead. In this case, the vehicle control ECU  20  is structured to acquire, from the navigation device  1 , the present location of the vehicle, map information, etc. 
     According to the description of the present embodiment, the autonomous driving control for allowing the vehicle to travel autonomously without a driving operation by a driver means that the vehicle control ECU  20  controls, out of vehicle operations, all of an accelerator operation, a brake operation, and a steering operation that are operations associated with the behavior of the vehicle. Alternatively, the autonomous driving control may mean that the vehicle control ECU  20  controls, out of vehicle operations, at least one of an accelerator operation, a brake operation, and a steering operation that are operations associated with the behavior of the vehicle. On the other hand, the manual driving by a driving operation of a user means that a user performs, out of vehicle operations, all of an accelerator operation, a brake operation, and a steering operation that are operations associated with the behavior of the vehicle. 
     Exemplary embodiments riot only to a navigation device but also to a device that is communicatively connected to the vehicle control ECU  20 . For example, embodiments include a mobile phone, a smartphone, a tablet terminal, a personal computer, etc. (hereinafter referred to as a mobile terminal or the like). Further, embodiments include a system having a server and the mobile terminal or the like. In this case, either the server or the mobile terminal or the like executes any step in the autonomous driving start program (refer to  FIG. 2 ) and the autonomous driving control change program (refer to  FIGS. 3, 4 ). However, in embodiments including the mobile terminal or the like, a vehicle that is allowed to perform the autonomous driving control and the mobile terminal or the like need to be communicatively connected to each other (in a wired or wireless manner). 
     While the autonomous driving assistance system is described above with reference to the embodiment, the autonomous driving assistance system can have structures and effects described below. 
     For example, a first structure includes the following: vehicle location acquiring means for acquiring a present location of a vehicle; road shape acquiring means for acquiring a road shape of a road where the vehicle travels; control content setting means for setting, on the basis of the present location of the vehicle and the road shape of the road where the vehicle travels, control content of first autonomous driving control that causes the vehicle to travel without deviating from a lane and second autonomous driving control that controls a speed of the vehicle in accordance with the road shape; control performing means for performing the first autonomous driving control or the second autonomous driving control in compliance with the control content set by the control content setting means; operation detecting means for detecting a steering operation by a driver of the vehicle; and control manner changing means for continuing or stopping the first autonomous driving control or the second autonomous driving control being performed in the vehicle, on the basis of a result detected by the operation detecting means, the present location of the vehicle, and the road shape of the road where the vehicle travels. The autonomous driving assistance system having the above structure determines, on the basis of presence or absence of detection of the steering operation by the driver, the shape of the surrounding road, and the content of the autonomous driving control being performed, whether to continue or stop the autonomous driving control in the vehicle that travels by using the autonomous driving control. Thus, if the steering operation by the driver is detected, there is no possibility that all the autonomous driving control is equally stopped in the same manner as in the related art. This makes it possible to prevent an increase in the burden on the driver in driving the vehicle, associated with stopping the autonomous driving control. 
     A second structure is as follows: the road shape acquiring means acquires, as lane-related information, lane demarcation on the road where the vehicle travels and road connection for each lane; when the operation detecting means detects the steering operation by the driver, the control manner changing means determines, on the basis of the lane-related information and the road shape of the road where the vehicle travels, whether only a lane different from a lane where the vehicle presently stays corresponds to a performance subject lane where the second autonomous driving control is to be performed; and when determining that only the lane different from the lane where the vehicle presently stays corresponds to the performance subject lane, the control manner changing means continues the second autonomous driving control being performed in the vehicle. The autonomous driving assistance system having the above structure, if the steering operation by the driver is detected, continues the autonomous driving control in a situation where the autonomous driving control does not need to be stopped. This makes it possible to prevent the increase in the burden on the driver in driving the vehicle, associated with stopping the autonomous driving control. 
     A third structure is as follows: the road shape acquiring means acquires, as lane-related information, lane demarcation on the road where the vehicle travels and road connection for each lane; while the operation detecting means does not detect the steering operation by the driver, the control manner changing means determines, on the basis of the lane-related information and the road shape of the road where the vehicle travels, whether only a lane different from a lane where the vehicle presently stays corresponds to a performance subject lane where the second autonomous driving control is to be performed; and when determining that only the lane different from the lane where the vehicle presently stays corresponds to the performance subject lane, the control manner changing means stops the second autonomous driving control being performed in the vehicle. The autonomous driving assistance system having the above structure, when the steering operation by the driver is not detected, allows the autonomous driving control to be stopped in a situation where the autonomous driving control needs to be stopped. This makes it possible to perform the autonomous driving control in accordance with a change in the situation of the vehicle, caused by the fact that the vehicle operation is not performed. 
     A fourth structure is as follows: the road shape acquiring means acquires, as lane-related information, lane demarcation on the road where the vehicle travels and road connection for each lane; while the operation detecting means does not detect the steering operation by the driver, the control manner changing means determines, on the basis of the lane-related information and the road shape of the road where the vehicle travels, whether only a lane where the vehicle presently stays corresponds to a performance subject lane where the second autonomous driving control is to be performed; and when determining that only the lane where the vehicle presently stays corresponds to the performance subject lane, the control manner changing means continues the second autonomous driving control being performed in the vehicle. The autonomous driving assistance system having the above structure continuously performs the autonomous driving control when the steering operation by the driver is not detected, thus making it possible to continuously perform the autonomous driving control necessary for the situation of the vehicle. 
     A fifth structure is as follows: the road shape acquiring means acquires, as lane-related information, lane demarcation on the road where the vehicle travels and road connection for each lane; when the operation detecting means detects the steering operation by the driver, the control manner changing means determines, on the basis of the lane-related information and the road shape of the road where the vehicle travels, whether only a lane where the vehicle presently stays corresponds to a performance subject lane where the second autonomous driving control is to be performed; and when determining that only the lane where the vehicle presently stays corresponds to the performance subject lane, the control manner changing means stops the second autonomous driving control being performed in the vehicle. The autonomous driving assistance system having the above structure allows the autonomous driving control to be stopped when the steering operation by the driver is detected in a situation where the autonomous driving control needs to be stopped. This makes it possible to perform the autonomous driving control in accordance with a change in the situation of the vehicle, caused by the vehicle operation. 
     A sixth structure is as follows: when the road where the vehicle travels has a branch point, the road shape acquiring means acquires, as branch-point-related information, lane demarcation, road connection for each lane, and a road shape of each route after the branch point; while the operation detecting means does not detect the steering operation by the driver, the control manner changing means determines, on the basis of the branch-point-related information and the road shape of the road where the vehicle travels, whether each lane branching off at the branch point of the road has a performance subject lane where the second autonomous driving control is to be performed and whether a lane where the vehicle presently stays is different from a performance subject lane where the second autonomous driving control is to be performed presently; and when determining that each lane branching off at the branch point of the road has the performance subject lane and that the lane where the vehicle presently stays is different from the performance subject lane where the second autonomous driving control is to be performed presently, the control manner changing means changes the control content of the second autonomous driving control being performed in the vehicle. The autonomous driving assistance system having the above structure allows the control content of the autonomous driving control to be changed as necessary when the steering operation by the driver is not detected. This makes it possible to perform the autonomous driving control in accordance with a change in the situation of the vehicle. 
     A seventh structure is as follows: the performance subject lane is a lane connecting to a curve or is a deceleration lane. The autonomous driving assistance system having the above structure makes it possible to correctly determine, on the basis of the lane demarcation and whether each lane connects to a curve or a deceleration lane, whether to continue or stop the autonomous driving control. 
     An eighth structure is as follows: the road shape acquiring means acquires deceleration lane information that identifies a deceleration lane on the road; the control content setting means sets, on the basis of the present location of the vehicle and the deceleration lane information, the control content of the first autonomous driving control and the second autonomous driving control for the deceleration lane; and when the operation detecting means detects the steering operation by the driver while the control performing means performs the first autonomous driving control and the second autonomous driving control in compliance with the control content that the control content setting means sets for the deceleration lane, the control performing means changes the control content of the first autonomous driving control and the second autonomous driving control from the control content for the deceleration lane to the control content for allowing the vehicle to travel in the same lane at a preset speed. The autonomous driving assistance system having the above structure allows the control content of the autonomous driving control to be changed when the steering operation by the driver is detected. This makes it possible to perform the autonomous driving control in accordance with a change in the situation of the vehicle, caused by the vehicle operation. 
     A ninth structure is as follows: when the operation detecting means detects the steering operation by the driver, the control manner changing means temporarily stops the first autonomous driving control until the operation is finished. The autonomous driving assistance system having the above structure makes it possible to appropriately perform the autonomous driving control that causes the vehicle to travel without deviating from a lane when the steering operation by the driver is detected. 
     A tenth structure is as follows: the control manner changing means further includes operation requirement determining means for determining, on the basis of the road shape of the road where the vehicle travels and the control content of the second autonomous driving control being performed in the vehicle, whether a situation requires the driver to perform the steering operation in order to allow the vehicle to continue the second autonomous driving control; and the control manner changing means continues or stops the second autonomous driving control being performed in the vehicle, on the basis of the result detected by the operation detecting means and a result determined by the operation requirement determining means. The autonomous driving assistance system having the above structure determines, on the basis of presence or absence of detection of the steering operation by the driver, the shape of the surrounding road, and the content of the autonomous driving control being performed, whether to continue or stop the autonomous driving control in the vehicle that travels by using the autonomous driving control. Thus, if the vehicle operation by the driver is detected, there is no possibility that all the autonomous driving control is equally stopped as in the same manner as in the related art. This prevents an increase in the burden on the driver in driving the vehicle, associated with stopping the autonomous driving control. 
     An eleventh structure is as follows: when there is a control subject section ahead in a direction of travel of the vehicle, the control content of the second autonomous driving control being performed in the vehicle is control for traveling in the control subject section, and only a lane different from a lane where the vehicle travels connects to the control subject section, the operation requirement determining means determines that the situation requires the driver to perform the steering operation in order to allow the vehicle to continue the second autonomous driving control. The autonomous driving assistance system having the above structure makes it possible to correctly determine whether the situation requires the driver to perform the steering operation in order to allow the vehicle to continue the autonomous driving control. 
     A twelfth structure is as follows: influence estimating means for estimating whether the steering operation by the driver influences performance of the second autonomous driving control is included; and when it is estimated that the steering operation by the driver influences the performance of the second autonomous driving control, the control manner changing means continues or stops the second autonomous driving control being performed in the vehicle, on the basis of the result detected by the operation detecting means and the result determined by the operation requirement determining means. The autonomous driving assistance system having the above structure makes it possible to determine whether to continue or stop the autonomous driving control on the basis of the steering operation by the driver, only when it is estimated that the steering operation by the driver influences the performance of the autonomous driving control. 
     A thirteenth structure is as follows: when there is a branch point ahead in a direction of travel of the vehicle, and only part of routes branching off at the branch point has the control subject section, the influence estimating means estimates that the steering operation by the driver influences the performance of the second autonomous driving control. The autonomous driving assistance system having the above structure makes it possible to correctly estimate when the steering operation by the driver influences the performance of the autonomous driving control. 
     A fourteenth structure is as follows: the road shape acquiring means acquires deceleration lane information that identifies a deceleration lane on the road; the control content setting means sets, on the basis of the present location of the vehicle and the deceleration lane information, the control content of the first autonomous driving control and the second autonomous driving control for the deceleration lane; and when the first autonomous driving control and the second autonomous driving control are performed in compliance with the control content that the control content setting means sets for the deceleration lane, the influence estimating means estimates that the steering operation by the driver influences the performance of the second autonomous driving control. The autonomous driving assistance system having the above structure makes it possible to correctly estimate when the steering operation by the driver influences the performance of the autonomous driving control. 
     A fifteenth structure is as follows: the control subject section is a curve or a deceleration lane; when the control subject section is the curve, the control content setting means sets the control content of the second autonomous driving control that causes deceleration to the speed corresponding to a radius of curvature of the curve before entry to the curve; and When the control subject section is the deceleration lane, the control content setting means sets the control content of the second autonomous driving control that limits acceleration. The autonomous driving assistance system having the above structure makes it possible to perform the autonomous driving control in accordance with the situation of the vehicle.