Automatic operation control apparatus and automatic operation control program

Abstract

To provide an automatic operation control apparatus that can suppress discomfort of a driver while improving fuel saving performance.SOLUTION: An automatic driving ECU 100 as an automatic operation control apparatus comprises a travel control unit 22 and a coursing determination unit 23. The travel control unit 22 executes adaptive cruise control that controls at least a vehicle speed of a self-vehicle Am instead of a driver. If the driver is not watching ahead of the self-vehicle Am in an execution period of the adaptive cruise control, the coursing determination unit 23 facilitates executing coursing control which makes the self-vehicle Am travel with inertia as compared when the driver is watching ahead of the vehicle.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The disclosure of this specification relates to technology for automatic driving control. [Background technology]

[0002] Patent Document 1 discloses a vehicle cruise control device capable of executing cruise control and coasting control. This cruise control device specifies an upper limit vehicle speed and a lower limit vehicle speed for a target vehicle speed set in cruise control, and repeats engine acceleration running and coasting within the range between the upper limit vehicle speed and the lower limit vehicle speed. Furthermore, by widening the range between the upper limit vehicle speed and the lower limit vehicle speed, it is possible to reduce discomfort caused by frequent switching between acceleration and deceleration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-014205 A Summary of the Invention [Problem to be solved by the invention]

[0004] In coasting control for coasting, as in Patent Document 1, if the range between the upper and lower vehicle speed limits is widened, frequent switching between acceleration and deceleration can be reduced, but large vehicle speed fluctuations can occur. Therefore, when a large vehicle speed fluctuation occurs while the driver is looking ahead, the positional relationship between the surrounding vehicles and the vehicle itself may deviate from what the driver expects, causing a sense of discomfort to the driver.

[0005] The present disclosure aims to provide an automatic driving control device and an automatic driving control program that are capable of improving fuel efficiency performance through coasting control while suppressing a sense of discomfort felt by the driver. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, one disclosed embodiment is an automatic driving control device that includes a driving control unit (22) that executes adaptive cruise control that controls at least the vehicle speed of the host vehicle (Am) on behalf of the driver, and a coasting control unit (23) that makes it easier to execute coasting control, which causes the host vehicle to coast by inertia, when the driver is not looking ahead of the host vehicle during the execution period of the adaptive cruise control, compared to when the driver is looking ahead.

[0007] One aspect disclosed is an automatic driving control program that causes at least one computer (10) to function to include a driving control unit (22) that executes adaptive cruise control that at least controls the vehicle speed of the vehicle (Am) on behalf of the driver, and a coasting control unit (23) that makes it easier to execute coasting control, which causes the vehicle to coast by inertia, when the driver is not looking ahead of the vehicle during the execution period of the adaptive cruise control, compared to when the driver is looking ahead.

[0008] In these aspects, the coasting control is easily performed when the driver is not watching the road ahead of the vehicle. Therefore, even if a large vehicle speed fluctuation occurs due to active coasting control, such a vehicle speed fluctuation is unlikely to cause discomfort to the driver who is not watching the road ahead. As a result, it is possible to suppress discomfort felt by the driver while improving fuel efficiency.

[0009] In addition, the reference numbers in parentheses in the above and claims are merely examples of the correspondence with specific configurations in the embodiments described below, and do not limit the technical scope in any way. In addition, claims that are not explicitly stated in the claims can be combined together if there is no particular problem with the combination. [Brief description of the drawings]

[0010] [Figure 1]FIG. 1 is a diagram showing an overall view of an in-vehicle network including an autonomous driving ECU according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is a diagram showing an example of a configuration of a powertrain including an engine as a power source. [Diagram 3] FIG. 1 is a diagram showing an example of a configuration of a powertrain including a motor generator as a power source. [Figure 4] 1 is a table illustrating parameters used in coasting control. [Diagram 5] 4 is a flowchart showing details of a driving control process performed by an autonomous driving ECU. [Figure 6] 5 is a flowchart showing details of a coasting determination process performed by an autonomous driving ECU. [Figure 7] FIG. 13 is a diagram for explaining the effect of expanding the vehicle speed fluctuation range in a single driving scene. [Figure 8] FIG. 13 is a diagram for explaining a following driving scene in which entry onto a descending slope is planned. [Figure 9] 9 is a diagram for explaining the effect of expanding the vehicle speed fluctuation range and the vehicle headway fluctuation range in the following driving scene shown in FIG. 8. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The function of the automatic driving control device according to an embodiment of the present disclosure is realized by an automatic driving ECU (Electronic Control Unit) 100 shown in Figures 1 and 2. The automatic driving ECU 100 is mounted on a vehicle (hereinafter, the host vehicle Am). By mounting the automatic driving ECU 100, the host vehicle Am becomes an automatic driving vehicle or an autonomous vehicle equipped with an automatic driving function, and is capable of running by the automatic driving function.

[0012] The autonomous driving ECU 100 is an in-vehicle ECU that realizes an autonomous driving function that can take over driving operations from the driver. In addition to driving assistance of about level 1, the autonomous driving ECU 100 can implement advanced driving assistance or partial autonomous driving of about level 2, and autonomous driving of level 3 or higher in which the system is the main control entity. The autonomous driving levels in this disclosure are based on standards defined by the Society of Automotive Engineers.

[0013] Autonomous driving at level 2 or below (less than level 3) is considered to be eyes-on autonomous driving, which requires the driver to visually monitor the area around the vehicle. Level 2 autonomous driving includes hands-on autonomous driving, in which the driver is required to hold the steering wheel, and hands-off autonomous driving, in which the driver is not required to hold the steering wheel.

[0014] Level 3 autonomous driving is eyes-off autonomous driving, which means that there is no need to monitor the surroundings of the vehicle. The autonomous driving ECU 100 may be capable of Level 4 fully autonomous driving, where the system performs all driving tasks under certain conditions. Level 4 autonomous driving is brain-off autonomous driving, where there is essentially no request for the driver to take over driving.

[0015] The autonomous driving ECU 100 switches the control state of the autonomous driving function among a plurality of control states including at least autonomous driving control with a surrounding monitoring obligation of Level 2 or lower, and autonomous driving control without a surrounding monitoring obligation of Level 3 or higher. In the following description, autonomous driving control of Level 2 or lower will be referred to as "driving assistance control," and autonomous driving control of Level 3 or higher will be referred to as "autonomous driving control."

[0016] During the autonomous driving period in which the vehicle Am is driven by the autonomous driving control, the driver may be permitted to perform a specific action other than driving that is prescribed in advance (hereinafter, a second task). The driver is legally permitted to perform the second task until a driving handover request is issued from the system. For example, viewing entertainment content such as video content, operating a device such as a smartphone, and eating are assumed as second tasks.

[0017] [In-vehicle system configuration] The autonomous driving ECU 100 is communicatively connected to a communication bus of an in-vehicle network mounted on the host vehicle Am. A driver monitoring system (DMS) 30, a host vehicle sensor 40, an external sensor 50, an operation unit 60, and the like are connected to the communication bus. Furthermore, a control device (powertrain ECU) that controls a powertrain 70, a control device (brake ECU) that controls a brake system 80, and the like are further connected to the communication bus. These nodes connected to the communication bus can communicate with each other. Certain of these nodes may be directly electrically connected to each other and can communicate with each other without going through the communication bus.

[0018] The DMS 30 includes a near-infrared light source, a near-infrared camera, and a control unit for controlling them, and monitors the driver's state. The DMS 30 is installed, for example, on the upper surface of the steering column or the upper surface of the instrument panel, with the near-infrared camera facing the headrest of the driver's seat. The DMS 30 uses the near-infrared camera to capture an image of the driver's face illuminated with near-infrared light from the near-infrared light source. The image captured by the near-infrared camera is subjected to image analysis by the control unit. The control unit extracts information such as the position and line of sight of the driver from the captured image. The DMS 30 provides the position information and line of sight direction information of the eye point extracted by the control unit to the autonomous driving ECU 100, etc., as detection information on the driver's state (hereinafter, driver detection information).

[0019] The DMS 30 may include a visible light camera instead of the near-infrared light source and the near-infrared camera. Also, a sensor other than a camera, such as a LiDAR scanner, and a wearable terminal that measures vital data such as the driver's respiratory rate, heart rate, blood pressure, and body temperature, may be used as the DMS 30. Furthermore, the DMS 30 may be capable of monitoring the state of passengers other than the driver.

[0020] The host vehicle sensor 40 is an in-vehicle sensor that is mounted on the host vehicle Am and detects the state of the host vehicle Am. The host vehicle Am is equipped with, for example, a vehicle speed sensor and an IMU (Inertial Measurement Unit) as the host vehicle sensor 40. The vehicle speed sensor is provided at the hub portion of each wheel of the host vehicle Am. The vehicle speed sensor generates vehicle speed information indicating the current traveling speed of the host vehicle Am and sequentially outputs the generated vehicle speed information to the communication bus.

[0021] The IMU includes an acceleration sensor and a gyro sensor. The IMU is provided near the center of gravity of the host vehicle Am and detects acceleration acting in the front-rear direction of the host vehicle Am, and angular velocity in the pitch direction occurring around the pitch axis, etc. The IMU may further detect acceleration acting in the left-right direction of the host vehicle Am, acceleration acting in the up-down direction, angular velocity in the yaw direction occurring around the yaw axis, and angular velocity in the roll direction occurring around the roll axis, etc. The IMU sequentially outputs current acceleration information and angular velocity information of the host vehicle Am to the communication bus.

[0022] The external sensor 50 is an in-vehicle sensor mounted on the host vehicle Am to acquire external information around the host vehicle necessary for autonomous driving. The host vehicle Am is equipped with, for example, a GNSS (Global Navigation Satellite System) sensor, a front camera, and a millimeter wave radar as the external sensor 50. The GNSS sensor sequentially detects the current position of the host vehicle Am by receiving positioning signals transmitted from multiple artificial satellites (positioning satellites). The GNSS sensor generates position information indicating the current position of the host vehicle Am and sequentially outputs the generated position information to a communication bus.

[0023] The front unit and the millimeter wave radar are autonomous sensors that monitor the surrounding environment of the vehicle Am. The front camera generates a forward image capturing the range in front of the vehicle Am. The front camera outputs the forward image or the analysis result of the forward image to the communication bus as detection information. The millimeter wave radar irradiates millimeter waves or quasi-millimeter waves toward the forward range, front side range, rear range, rear side range, etc. of the vehicle Am. The millimeter wave radar generates detection information of targets around the vehicle by receiving reflected waves reflected by moving objects and stationary objects around the vehicle, and outputs the generated detection information to the communication bus. Note that autonomous sensors such as a rear camera, a surround camera, a lidar, and a sonar may be mounted on the vehicle Am as the external sensor 50.

[0024] The operation unit 60 is an input unit that accepts user operations by the driver, etc. User operations related to starting and stopping an automatic driving function, for example, are input to the operation unit 60. A steering switch provided on the spokes of the steering wheel, an operation lever provided on the steering column, a center display with a touch panel function, a voice input device that recognizes the contents of the driver's speech, etc. can be used as the operation unit 60. The operation unit 60 outputs operation information based on the user operation to a communication bus.

[0025] The powertrain 70 includes a power source that generates driving force for propelling the host vehicle Am, and a drive system that transmits the driving force to the drive wheels DW (see Figs. 2 and 3). At least one of an engine 71 and a motor generator 75 is used as the power source. The drive system is made up of a transmission 72 having a gear 73 and a clutch 74, a differential 76, and the like. In the powertrain 70 that uses only the motor generator 75 as the power source, the transmission 72 may be omitted (see Fig. 3).

[0026] The powertrain 70 further includes a powertrain ECU. The powertrain ECU is an on-board computer mainly composed of a microcontroller. The powertrain ECU controls the operation of the engine 71, the transmission 72, the motor generator 75, etc., and generates a driving force and a braking force (engine brake or regenerative force) as a control target on the drive wheels DW.

[0027] The brake system 80 includes brake units provided on each wheel of the vehicle Am and a hydraulic system for operating each brake unit. The brake units may be disc brakes, drum brakes, etc. The hydraulic system includes an electric hydraulic pump that generates brake pressure, an electric brake booster that controls the brake pressure, and brake pipes that connect the electric brake booster to each brake unit.

[0028] The brake system 80 further includes a brake ECU. The brake ECU is an on-board computer mainly composed of a microcontroller. The brake ECU controls the operation of the electric brake booster to generate a braking force as a control target in the brake unit of each wheel.

[0029] [Autonomous Driving ECU Configuration] The autonomous driving ECU 100 is a computer that mainly includes a control circuit 10 that includes a processing unit 11, a RAM 12, a storage unit 13, an input / output interface 14, and a bus connecting these units. The processing unit 11 accesses the RAM 12 to execute various processes (instructions) for implementing the autonomous driving control method of the present disclosure. The storage unit 13 stores various programs (autonomous driving control programs, etc.) that are executed by the processing unit 11. By executing the programs by the processing unit 11, the autonomous driving ECU 100 is configured with an information acquisition unit 21, a driving control unit 22, a coasting determination unit 23, etc. as multiple functional units for implementing the autonomous driving function.

[0030] The information acquisition unit 21 acquires information output from each node of the in-vehicle network to the communication bus. The information acquisition unit 21 acquires driver detection information from the DMS 30. The information acquisition unit 21 acquires vehicle speed information, acceleration information, and the like from the vehicle sensor 40. The information acquisition unit 21 acquires position information, detection information, and the like from the external sensor 50. The information acquisition unit 21 acquires operation information, and the like from the operation unit 60.

[0031] The travel control unit 22 executes adaptive cruise control to control the vehicle speed (hereinafter, host vehicle speed Vm, see FIG. 7) and the forward vehicle distance Df (see FIG. 9) of the host vehicle Am on behalf of the driver. The forward vehicle distance Df is the distance between the host vehicle Am and a vehicle ahead (hereinafter, preceding vehicle Af, see FIG. 8) traveling in the same lane as the host vehicle Am. Through adaptive cruise control, the host vehicle Am continues traveling while maintaining the target speed set by the driver and the distance between the preceding vehicle Af and the host vehicle Am without the driver operating the accelerator.

[0032] The driving control unit 22 acquires operation information, position information, detection information, vehicle speed information, acceleration information, and the like through the information acquisition unit 21. The driving control unit 22 may further acquire map data showing the shape of the road ahead of the host vehicle. The driving control unit 22 can combine lane keeping control with adaptive cruise control. The driving control unit 22, which executes adaptive cruise control and lane keeping control, recognizes the dividing lines of the host vehicle's lane and the preceding vehicle Af, and the like, based on detection information, and automatically drives the host vehicle Am along the host vehicle's lane without relying on the driver's driving operation.

[0033] When the driving control unit 22 grasps a user operation instructing the activation of adaptive cruise control based on the operation information, the driving control unit 22 starts adaptive cruise control. In adaptive cruise control, the driving control unit 22 controls the acceleration / deceleration of the host vehicle Am by outputting a required torque to the power train 70 and the brake system 80. When the preceding vehicle Af is not recognized, the driving control unit 22 controls the acceleration / deceleration of the host vehicle Am so as to maintain a vehicle speed set by the driver (hereinafter, set vehicle speed SS, see FIG. 7). On the other hand, when the preceding vehicle Af is recognized, the driving control unit 22 controls the acceleration / deceleration by the power train 70 so as to maintain a vehicle distance set by the driver (hereinafter, set vehicle distance SD, see FIG. 9). The set vehicle distance SD can be switched among three stages such as "long (far), medium, short (close)" or five stages such as "long, slightly long, medium, slightly short, short" based on the user operation.

[0034] The driving control unit 22 executes adaptive cruise control in a state where the driver is not required to monitor the surroundings on expressways, motorways, and the like where implementation of autonomous driving control of level 3 or higher is permitted. The driving control unit 22 provides the coasting determination unit 23 with information indicating whether or not the driver is required to monitor the surroundings for the adaptive cruise control being executed, in other words, information indicating the autonomous driving level of the control being executed (hereinafter, AD level information).

[0035] The coasting determination unit 23 determines whether or not to execute coasting control during the execution period of adaptive cruise control. Coasting control is coasting control that coasts the host vehicle Am. The coasting control reduces the drive energy that drives the host vehicle Am, making it possible to improve fuel economy. In this disclosure, the improvement in fuel economy includes not only reducing the amount of fuel used by the engine 71 for traveling, but also reducing the amount of power used by the motor generator 75 for traveling (so-called electricity saving).

[0036] The coasting determination unit 23 executes coasting control in cooperation with the cruise control unit 22 and the powertrain 70 by outputting a coasting execution request to the cruise control unit 22. Specifically, when the powertrain 70 having a clutch 74 in its drive system is the control target (see FIG. 2), the clutch 74 is released in coasting control. As a result, the power source such as the engine 71 and the motor generator 75 is disconnected from the drive wheels DW. The power source may be disconnected from the drive wheels DW by placing the transmission 72 in neutral. As a result of the above, the host vehicle Am coasts against the running resistance with the drive source stopped.

[0037] Furthermore, when the motor generator 75 is used as the power source and the power train 70 does not include the clutch 74 (see FIG. 3), the coasting control stops both the driving and regeneration by the motor generator 75. As a result, the host vehicle Am coasts against the running resistance including the drag resistance of the motor generator 75.

[0038] When the coasting control is executed, the host vehicle Am will travel by inertia, and therefore will not be able to maintain the set vehicle speed SS or the set vehicle distance SD. Therefore, the coasting determination unit 23 provides an allowable range for the set vehicle speed SS and the set vehicle distance SD (see FIG. 4). Specifically, when the travel control unit 22 is executing adaptive cruise control to control the host vehicle speed Vm, the coasting determination unit 23 prescribes an allowable range of vehicle speed fluctuation (hereinafter, vehicle speed fluctuation range CSR, see FIG. 7, etc.) based on the set vehicle speed SS. As an example, the coasting determination unit 23 sets an upper limit value (hereinafter, vehicle speed upper limit value ULs) of the vehicle speed fluctuation range CSR that allows the continuation of the coasting control to the same speed as the set vehicle speed SS. In addition, the coasting determination unit 23 sets a lower limit value (hereinafter, vehicle speed lower limit value LLs) of the vehicle speed fluctuation range CSR to a speed that is lower than the set vehicle speed SS by a predetermined speed (for example, about 5 km / h).

[0039] When adaptive cruise control that controls the inter-vehicle distance is being executed by the cruise control unit 22, the coasting determination unit 23 determines the vehicle speed fluctuation range CSR based on the vehicle speed of the preceding vehicle Af (hereinafter, preceding vehicle speed Vf) as a reference (see FIG. 9). The coasting determination unit 23 adopts the preceding vehicle speed Vf instead of the set vehicle speed SS. As an example, the coasting determination unit 23 sets the vehicle speed upper limit ULs to the same speed as the preceding vehicle speed Vf, and sets the vehicle speed lower limit LLs to a predetermined speed (e.g., about 5 km / h) lower than the preceding vehicle speed Vf.

[0040] Furthermore, the coasting determination unit 23 determines the allowable range of inter-vehicle fluctuation (hereinafter, inter-vehicle fluctuation range CDR, see FIG. 9) based on the set inter-vehicle distance SD. As an example, the coasting determination unit 23 sets the upper limit value of the inter-vehicle fluctuation range CDR (hereinafter, inter-vehicle upper limit value ULd) at which continuation of coasting control is permitted to be a predetermined distance (e.g., about 10 m) longer than the set inter-vehicle distance SD. In addition, the coasting determination unit 23 sets the lower limit value of the inter-vehicle fluctuation range CDR (hereinafter, inter-vehicle lower limit value LLd) to the same distance as the set inter-vehicle distance SD.

[0041] [Coasting control details] When the coasting control described above is executed, the autonomous driving ECU 100 achieves fuel saving by repeating gentle acceleration and deceleration so as not to deviate from the vehicle speed fluctuation range CSR or the vehicle distance fluctuation range CDR. However, if the positional relationship between the host vehicle Am and other vehicles around the host vehicle deviates from the driver's assumption due to the execution of the coasting control, the driver may feel uncomfortable. As described above, the improvement of fuel saving performance by the coasting control may be in a trade-off relationship with the driver's sense of discomfort.

[0042] Therefore, the autonomous driving ECU 100 switches the coasting control on and off depending on the driver's gaze point, thereby improving fuel efficiency while suppressing the driver's sense of discomfort. The autonomous driving ECU 100 performs active coasting control in a scene where the driver does not need to gaze ahead due to the execution of autonomous driving control of autonomous driving level 3 or higher, enabling fuel efficiency while preventing the driver from feeling uncomfortable.

[0043] In detail, the coasting determination unit 23 determines whether or not the driver is gazing ahead based on the driver detection information (gaze direction information) of the DMS 30 acquired through the information acquisition unit 21. In addition, the coasting determination unit 23 determines whether or not the driver has a duty to monitor the surroundings during the adaptive cruise control being executed based on the AD level information acquired from the driving control unit 22. When the driver is not gazing ahead of the host vehicle Am during the execution period of the adaptive cruise control in which the driver does not have a duty to monitor the surroundings, the coasting determination unit 23 makes it easier to execute coasting control than when the driver is gazing ahead.

[0044] When the driver is not gazing ahead of the host vehicle Am, the coasting judgment unit 23 changes the vehicle speed fluctuation range CSR and the vehicle distance fluctuation range CDR to make it easier to execute coasting control compared to when the driver is gazing ahead. Specifically, when the driving control unit 22 is executing adaptive cruise control control to control the host vehicle speed Vm, the coasting judgment unit 23 expands the vehicle speed fluctuation range CSR (see FIG. 7). Also, when the driving control unit 22 is executing adaptive cruise control control to control the forward vehicle distance Df, the coasting judgment unit 23 expands the vehicle distance fluctuation range CDR (see FIG. 7 and FIG. 9) in addition to the vehicle speed fluctuation range CSR. The coasting judgment unit 23 expands each allowable range of the host vehicle speed Vm and the forward vehicle distance Df by switching parameters.

[0045] When the vehicle speed fluctuation range CSR is expanded, the coasting determination unit 23 changes (lowers) only the vehicle speed lower limit LLs among the vehicle speed upper limit ULs and the vehicle speed lower limit LLs that define the vehicle speed fluctuation range CSR. As an example, the coasting determination unit 23 sets the vehicle speed lower limit LLs to a speed that is lower than the set vehicle speed SS (see FIG. 7) by a predetermined speed (e.g., about 20 km / h) that is higher than when the driver is watching the road ahead (see pattern 1 in FIG. 4) (see pattern 2 in FIG. 4). The vehicle speed upper limit ULs is set to the same speed as the set vehicle speed SS, as in the case of watching the road ahead.

[0046] When the coasting determination unit 23 expands the headway fluctuation range CDR, it changes only the upper headway upper limit ULd of the upper headway upper limit ULd and the lower headway lower limit LLd that define the headway fluctuation range CDR. As an example, the coasting determination unit 23 eliminates the setting of the upper headway upper limit ULd (see pattern 2 in FIG. 4). The lower headway lower limit LLd is set to the same distance as the set headway SD (see FIG. 9), as in the case of looking ahead.

[0047] [Drive control processing and coasting judgment processing] Next, the details of the driving control processing and coasting judgment processing performed by the autonomous driving ECU 100 to realize the adaptive cruise control and coasting control described above will be explained based on Figures 5 and 6, with reference to Figures 1 and 4.

[0048] 5 is executed mainly by the cruise control unit 22 based on the activation of the adaptive cruise control. The cruise control is repeatedly executed by the coasting determination unit 23 until the adaptive cruise control is turned off.

[0049] In S11 of the driving control process, the driving control unit 22 calculates a required acceleration Av by vehicle speed feedback control based on the difference between a set vehicle speed SS (see FIG. 7) and a current vehicle speed indicated by the vehicle speed information. In S12, the driving control unit 22 determines whether or not there is a preceding vehicle Af (see FIG. 9) based on the detection information. If there is a preceding vehicle Af (S12: YES), in S13, the driving control unit 22 calculates a required acceleration Ad by vehicle distance feedback control based on the difference between a set vehicle distance SD (see FIG. 9) and a current vehicle distance indicated by the detection information. On the other hand, if there is no preceding vehicle Af (S12: NO), the driving control unit 22 skips the calculation of the required acceleration Ad in S13.

[0050] In S14, the coasting determination unit 23 performs a coasting determination process (described later) for determining whether the coasting control is on or off. In S15, the driving control unit 22 grasps the determination result in S14. Specifically, in S15, the driving control unit 22 determines whether a coasting execution request has been output from the coasting determination unit 23.

[0051] If there is no coasting execution request (S15: NO), the cruise control unit 22 outputs command values ​​for minimizing the required accelerations Av, Ad to the powertrain 70 and the brake system 80 in S16. In this manner, normal adaptive cruise control is executed. On the other hand, if there is a coasting execution request (S15: YES), the cruise control unit 22 outputs a coasting execution request to the powertrain 70 in S17. In this manner, coasting control is executed.

[0052] The coasting determination process shown in Fig. 6 is executed as a sub-process of the driving control process. In S101 of the coasting determination process, the coasting determination unit 23 determines the autonomous driving level of the adaptive cruise control currently being executed, based on the AD level information acquired from the driving control unit 22. If the adaptive cruise control currently being executed is autonomous driving level 2 or lower (less than level 3), and the driver has a duty to monitor the surroundings (S101: NO), the coasting determination unit 23 determines in S103 to employ parameter 1 (see Fig. 4) that has been prepared in advance.

[0053] On the other hand, when adaptive cruise control of autonomous driving level 3 or higher is being executed, that is, when the driver has no obligation to monitor the surroundings (S101: YES), the coasting determination unit 23 acquires driver detection information generated by the DMS 30 in S102. The coasting determination unit 23 determines whether the driver is gazing ahead or not based on the driver detection information. When the driver is gazing ahead (S102: YES), the coasting determination unit 23 decides to adopt a parameter 1 (see FIG. 4) prepared in advance in S103. On the other hand, when the driver is not gazing ahead (S102: NO), the coasting determination unit 23 decides to adopt a parameter 2 (see FIG. 4) prepared in advance in S104.

[0054] In S105, the coasting determination unit 23 determines whether or not there is a preceding vehicle Af (see FIG. 9) based on the detection information. If there is a preceding vehicle Af (S105: YES), in S106, the coasting determination unit 23 predicts the behavior of the preceding vehicle Af N seconds ahead (for example, about 5 seconds). Specifically, the coasting determination unit 23 predicts the behavior of the preceding vehicle Af, such as acceleration / deceleration, ascending and descending slopes, etc.

[0055] In S107, the coasting determination unit 23 predicts and calculates the fuel efficiency of the host vehicle Am N seconds from now, using the parameters selected in S101 to S104 as constraint conditions. Based on the result of the prediction calculation in S107, the coasting determination unit 23 determines in S108 whether the fuel efficiency of the host vehicle Am will improve up to N seconds from now. When the coasting determination unit 23 determines that the fuel efficiency will improve up to N seconds from now (S108: YES), it determines in S109 whether to execute coasting control. In this case, the coasting determination unit 23 sets a coasting request flag (see FIG. 7 and FIG. 9) to an ON state, and outputs a coasting execution request to the traveling control unit 22.

[0056] On the other hand, if it is determined that the fuel efficiency will not improve until N seconds later (S108: NO), the coasting judgment unit 23 skips the execution judgment of S109. In addition, if it predicts that the host vehicle speed Vm will deviate from the vehicle speed fluctuation range CSR or predicts that the forward vehicle distance Df will deviate from the vehicle distance fluctuation range CDR, the coasting judgment unit 23 also skips the execution judgment of S109. In these cases, the coasting judgment unit 23 turns off the coasting request flag and does not output a coasting execution request.

[0057] [Effects of active coasting control] Next, the effects of expanding the vehicle speed fluctuation range CSR and the headway fluctuation range CDR will be described in detail based on FIGS. 7 to 9 with reference to FIGS. 1 and 4. FIG.

[0058] In the scene of independent driving shown in Fig. 7, the driving control unit 22 executes adaptive cruise control so that the host vehicle speed Vm becomes the set vehicle speed SS. When the driver is watching the road ahead (see Fig. 7B), the coasting determination unit 23 sets the vehicle speed fluctuation range CSR to 5km / h by adopting parameter 1 (see Fig. 4). As a result, the coasting request flag is switched on and off, that is, the coasting control is repeatedly started and interrupted.

[0059] On the other hand, when the driver is not looking ahead (see FIG. 7A), the coasting judgment unit 23 employs parameter 2 (see FIG. 4) to lower the vehicle speed lower limit LLs below the normal state (when the driver is looking ahead). The coasting judgment unit 23 expands the vehicle speed fluctuation range CSR, which is the allowable fluctuation range of the host vehicle speed Vm, from 5 km / h to 20 km / h. As a result, the frequency of switching the coasting request flag on and off is reduced, and the time for each coasting control is lengthened. As a result, the fuel efficiency is also improved.

[0060] In the following driving scene of the preceding vehicle Af shown in Figures 8 and 9, there is a descending slope ahead of the preceding vehicle Af and the host vehicle Am. At time t1, the preceding vehicle Af and the host vehicle Am are both traveling on a horizontal flat road. Then, at time t2, the preceding vehicle Af enters the descending slope road before the host vehicle Am. Furthermore, at time t3, the host vehicle Am enters the descending slope road following the preceding vehicle Af.

[0061] The cruise control unit 22 executes adaptive cruise control so that the forward distance Df to the preceding vehicle Af becomes the set distance SD. When the driver is looking ahead (see FIG. 9B), the coasting determination unit 23 sets the distance fluctuation range CDR to 10 m by employing parameter 1 (see FIG. 4). As a result, after the preceding vehicle Af enters the descending slope, the coasting request flag is switched off, that is, the coasting control is interrupted, before the host vehicle Am enters the descending slope road (between time t2 and t3). As a result, the host vehicle Am accelerates before the descending slope road to maintain the forward distance Df, and then re-executes the coasting control.

[0062] On the other hand, when the driver is not looking ahead (see FIG. 9A), the coasting determination unit 23 eliminates the setting of the lower inter-vehicle limit value LLd by adopting parameter 2 (see FIG. 4). The coasting determination unit 23 expands the vehicle speed fluctuation range CSR, which is the allowable fluctuation range of the vehicle speed, from 10 m to a state with no upper limit. As a result, the coasting request flag is not switched off in a following driving scene, that is, the interruption of the coasting control is avoided. In this way, the coasting control is continued, and the effect of improving fuel efficiency is also increased.

[0063] (Summary of embodiments) In the present embodiment described above, when the driver is not watching ahead of the host vehicle Am, the coasting control is likely to be executed. Therefore, even if a large vehicle speed fluctuation occurs due to active execution of the coasting control, such a vehicle speed fluctuation is unlikely to cause discomfort to the driver who is not watching ahead. As a result, it is possible to suppress discomfort felt by the driver while improving fuel efficiency performance.

[0064] In addition, in this embodiment, driver detection information regarding the driver's state is acquired from the DMS 30 that monitors the driver's state. The coasting determination unit 23 determines whether the driver is gazing ahead based on the driver detection information. Then, when the driver is not gazing ahead of the host vehicle Am, the coasting determination unit 23 makes it easier to execute coasting control than when the driver is gazing ahead. As described above, by detecting the driver's gaze position using the DMS 30, the coasting determination unit 23 can appropriately grasp the period when the driver is not gazing ahead and actively execute coasting control. As a result, it is possible to more reliably achieve both improvement in fuel saving performance and suppression of discomfort felt by the driver.

[0065] In this embodiment, adaptive cruise control is performed in a state where the driver has no obligation to monitor the surroundings. The coasting determination unit 23 determines whether or not the adaptive cruise control being performed is in a state where the driver has an obligation to monitor the surroundings. When the driver does not have an obligation to monitor the surroundings, the coasting determination unit 23 makes it easier to execute coasting control than when the driver has an obligation to monitor the surroundings. As described above, by referring to the presence or absence of the driver's obligation to monitor the surroundings (automated driving level), the coasting determination unit 23 can appropriately determine the period when the driver is not looking ahead and actively execute coasting control.

[0066] Furthermore, in this embodiment, when adaptive cruise control for controlling the host vehicle speed Vm is being executed by the travel control unit 22, a vehicle speed fluctuation range CSR that permits continuation of the coasting control is defined. Then, by changing the vehicle speed fluctuation range CSR, the coasting determination unit 23 makes it easier to execute the coasting control when the driver is not looking ahead of the host vehicle Am than when the driver is looking ahead. In this way, by changing the vehicle speed fluctuation range CSR, the coasting determination unit 23 can appropriately adjust the ease of executing the coasting control. As a result, it is possible to more reliably achieve both improvement in fuel efficiency performance and suppression of discomfort felt by the driver.

[0067] In addition, the coasting determination unit 23 of this embodiment makes it easier to execute coasting control by lowering only the lower vehicle speed limit LLs among the upper vehicle speed limit ULs and the lower vehicle speed limit LLs that define the vehicle speed fluctuation range CSR. As a result, it is possible to change the vehicle speed fluctuation range CSR to be wider while preventing the host vehicle speed Vm from increasing too much during execution of coasting control. As a result, it is possible to achieve both improved fuel efficiency and suppression of discomfort felt by the driver while appropriately executing adaptive cruise control.

[0068] In this embodiment, when the driving control unit 22 is executing adaptive cruise control to control the forward distance Df, a vehicle-to-vehicle fluctuation range CDR that permits continuation of the coasting control is specified. Then, by changing the vehicle-to-vehicle fluctuation range CDR, the coasting determination unit 23 makes it easier to execute the coasting control when the driver is not looking ahead of the host vehicle Am than when the driver is looking ahead. In this way, by changing the vehicle-to-vehicle fluctuation range CDR, the coasting determination unit 23 can appropriately adjust the ease of executing the coasting control. As a result, it is possible to more reliably achieve both improvement of fuel efficiency performance and suppression of discomfort felt by the driver.

[0069] Furthermore, the coasting determination unit 23 of this embodiment makes it easier to execute coasting control by changing the inter-vehicle upper limit ULd and the inter-vehicle lower limit LLd that define the inter-vehicle fluctuation range CDR to eliminate the setting of the inter-vehicle upper limit ULd. As a result, it is possible to change the inter-vehicle fluctuation range CDR to be wider while avoiding excessive approach to the preceding vehicle Af during execution of coasting control. As a result, it is possible to achieve both improved fuel efficiency and suppression of discomfort felt by the driver while appropriately executing adaptive cruise control.

[0070] In the above embodiment, the control circuit 10 corresponds to a "computer", the coasting determination unit 23 corresponds to a "coasting control unit", and the automatic driving ECU 100 corresponds to an "automatic driving control device". In addition, the vehicle headway fluctuation range CDR and the vehicle speed fluctuation range CSR correspond to an "allowable range", the vehicle headway upper limit value ULd and the vehicle speed upper limit value ULs correspond to an "upper limit value", the vehicle headway lower limit value LLd and the vehicle speed lower limit value LLs correspond to a "lower limit value", and the host vehicle speed Vm corresponds to a "vehicle speed".

[0071] (Other embodiments) Although one embodiment of the present disclosure has been described above, the present disclosure should not be construed as being limited to the above embodiment, and can be applied to various embodiments and combinations within the scope not departing from the gist of the present disclosure.

[0072] In the above embodiment, the AD level information and the driver detection information are used to determine whether the driver is gazing ahead. The method of determining whether the driver is gazing ahead may be changed as appropriate. For example, the coasting determination unit 23 of the first modified example of the above embodiment uses only the AD level information to determine whether the driver is gazing ahead. Specifically, when autonomous driving control of autonomous driving level 3 or higher is being executed, the coasting determination unit 23 estimates that the driver is not gazing ahead, and when driving assistance control of autonomous driving level 2 or lower is being executed, the coasting determination unit 23 estimates that the driver is gazing ahead.

[0073] In addition, in variant example 2 of the above embodiment, when autonomous driving control is being executed by the driving control unit 22 and video content is being played using the center display, the coasting judgment unit 23 estimates that the driver is not looking ahead.

[0074] In the above embodiment, the vehicle speed fluctuation range CSR and the vehicle distance fluctuation range CDR are switched between two stages, pattern 1 and pattern 2. The switching of the allowable range is not limited to two stages, and may be switched between a number of patterns (three or more), or may be changed (expanded) continuously. For example, in Modification 3 of the above embodiment, the allowable fluctuation range of the host vehicle speed Vm and the vehicle distance Df ahead is expanded in the following order: level 2 or lower, level 3 or higher and looking ahead, and level 3 or higher and not looking ahead.

[0075] In the fourth modification of the above embodiment, the upper inter-vehicle distance limit value ULd in the pattern 2 is set to a value that is a predetermined distance (for example, about 20 m) longer than when the driver is watching the front. That is, instead of eliminating the upper inter-vehicle distance limit value ULd, the coasting determination unit 23 makes it easier to execute the coasting control when the driver is not watching the front by changing the upper inter-vehicle distance limit value ULd to be increased.

[0076] In the fifth modification of the above embodiment, the vehicle speed fluctuation range CSR is expanded by changing both the upper vehicle speed limit ULs and the lower vehicle speed limit LLs. In the sixth modification of the above embodiment, the vehicle speed fluctuation range CSR is expanded by increasing the upper vehicle speed limit ULs out of the upper vehicle speed limit ULs and the lower vehicle speed limit LLs.

[0077] In the seventh modification of the above embodiment, the vehicle headway fluctuation range CDR is expanded by changing both the upper vehicle headway limit ULd and the lower vehicle headway limit LLd. In the eighth modification of the above embodiment, the vehicle speed fluctuation range CSR is expanded by lowering the lower vehicle headway limit LLd out of the upper vehicle headway limit ULd and the lower vehicle headway limit LLd. The lowering of the lower vehicle headway limit LLd is achieved, for example, by temporarily automatically changing the set vehicle headway SD from "long" or "medium" to "short."

[0078] In the above embodiment, when coasting control is performed during execution of adaptive cruise control in the following driving mode, both the vehicle speed fluctuation range CSR and the vehicle headway fluctuation range CDR are expanded. In contrast, in the 9th modification of the above embodiment, only the vehicle headway fluctuation range CDR is expanded in the following driving mode out of the vehicle speed fluctuation range CSR and the vehicle headway fluctuation range CDR.

[0079] Furthermore, in the tenth modification of the above embodiment, the expansion range of the vehicle speed fluctuation range CSR in the following driving mode is different from the expansion range of the vehicle speed fluctuation range CSR in the independent driving mode. Specifically, the expansion range of the vehicle speed fluctuation range CSR in the following driving mode may be smaller or larger than the expansion range of the vehicle speed fluctuation range CSR in the independent driving mode.

[0080] In the above embodiment, each function provided by the autonomous driving ECU can be provided by software and hardware that executes the software, software alone, hardware alone, or a combination of these. Furthermore, when such a function is provided by an electronic circuit as hardware, each function can also be provided by a digital circuit including a large number of logic circuits, or an analog circuit.

[0081] The processing unit in the above embodiment includes at least one arithmetic core such as a central processing unit (CPU) and a graphics processing unit (GPU). The processing unit may further include a field-programmable gate array (FPGA), a neural network processing unit (NPU), and an IP core having other dedicated functions. The processing unit may be individually mounted on a printed circuit board, or may be mounted on an application specific integrated circuit (ASIC), a system on chip (SoC), and an FPGA.

[0082] The form of the storage medium (non-transitory tangible storage medium) that stores various programs and the like may be changed as appropriate. Furthermore, the storage medium is not limited to a configuration in which it is provided on a circuit board, and may be provided in the form of a memory card or the like, inserted into a slot portion, and electrically connected to a control circuit such as an autonomous driving ECU. Furthermore, the storage medium may be an optical disk, hard disk drive, solid state drive, or the like that is the source from which the program is copied or distributed to the autonomous driving ECU.

[0083] The vehicle equipped with the above-mentioned autonomous driving ECU is not limited to a general private passenger car, but may be a rental car vehicle, a manned taxi vehicle, a ride-sharing vehicle, a freight vehicle, a bus, etc. The vehicle equipped with the autonomous driving ECU may be a right-hand drive vehicle or a left-hand drive vehicle. Furthermore, the traffic environment in which the vehicle travels may be a traffic environment based on left-hand traffic or a traffic environment based on right-hand traffic. The autonomous driving control according to the present disclosure may be appropriately optimized according to the road traffic laws of each country and region, and further the steering wheel position of the vehicle, etc.

[0084] The control unit and the method described herein may be implemented by a special-purpose computer having a processor programmed to execute one or more functions embodied in a computer program. Alternatively, the device and the method described herein may be implemented by a special-purpose hardware logic circuit. Alternatively, the device and the method described herein may be implemented by one or more special-purpose computers configured by a combination of a processor that executes a computer program and one or more hardware logic circuits. The computer program may also be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by the computer. [Explanation of symbols]

[0085] 10 control circuit (computer), 21 information acquisition unit, 22 driving control unit, 23 coasting judgment unit (coasting control unit), 30 driver monitoring system (DMS), 100 automatic driving ECU (automatic driving control device), Am host vehicle, CSR vehicle speed fluctuation range (tolerable range of vehicle speed fluctuation), CDR vehicle distance fluctuation range (tolerable range of vehicle distance fluctuation), Df front vehicle distance, ULs vehicle speed upper limit value (upper limit value of vehicle speed fluctuation tolerance range), LLs vehicle speed lower limit value (lower limit value of vehicle speed fluctuation tolerance range), ULd vehicle distance upper limit value (upper limit value of vehicle distance fluctuation tolerance range), LLd vehicle distance lower limit value (lower limit value of vehicle distance fluctuation tolerance range), Vm host vehicle speed (vehicle speed)

Claims

1. A driving control unit (22) that executes adaptive cruise control to at least control the vehicle speed of the host vehicle (Am) on behalf of the driver; a coasting control unit (23) that makes it easier to execute coasting control for causing the vehicle to coast when the driver is not gazing ahead of the vehicle during an execution period of the adaptive cruise control control than when the driver is gazing ahead; An automatic driving control device equipped with the above.

2. An information acquisition unit (21) that acquires detection information related to the state of the driver from a driver monitoring system (30) that monitors the state of the driver, The automatic driving control device according to claim 1, wherein the coasting control unit determines whether the driver is looking ahead based on the detection information, and when the driver is not looking ahead of the vehicle, makes it easier to execute the coasting control than when the driver is looking ahead.

3. The driving control unit performs the adaptive cruise control in a state in which the driver has no obligation to monitor the surroundings, The coasting control unit is configured to determine whether the adaptive cruise control being executed is in a state in which the driver has the obligation to monitor the surroundings, and when the driver does not have the obligation to monitor the surroundings, makes it easier to execute the coasting control than when the driver has the obligation to monitor the surroundings.

4. The coasting control unit is When the adaptive cruise control for controlling the vehicle speed (Vm) is being executed by the driving control unit, a tolerable range of vehicle speed fluctuation (CSR) for permitting continuation of the coasting control is specified, The automatic driving control device according to claim 1 , wherein the change in the tolerance range makes it easier to execute the coasting control when the driver is not looking ahead of the vehicle than when the driver is looking ahead.

5. The automatic driving control device according to claim 4, wherein the coasting control unit makes it easier to execute the coasting control by changing only the lower limit value out of the upper limit value (ULs) and lower limit value (LLs) that define the allowable range of the vehicle speed fluctuation, thereby lowering the lower limit value.

6. The coasting control unit is When the adaptive cruise control for controlling the distance between vehicles (Df) ahead is being executed by the driving control unit, a tolerable range of distance fluctuation (CDR) for permitting continuation of the coasting control is specified, The automatic driving control device according to claim 1 , wherein the change in the tolerance range makes it easier to execute the coasting control when the driver is not looking ahead of the vehicle than when the driver is looking ahead.

7. The automatic driving control device according to claim 6, wherein the coasting control unit makes it easier to execute the coasting control by changing an upper limit value (ULd) and a lower limit value (LLd) that define the allowable range of the vehicle-to-vehicle variation, by either increasing only the upper limit value or by eliminating the setting of the upper limit value.

8. A driving control unit (22) that executes adaptive cruise control to at least control the vehicle speed of the host vehicle (Am) on behalf of the driver; a coasting control unit (23) that makes it easier to execute coasting control for causing the vehicle to coast when the driver is not gazing ahead of the vehicle during an execution period of the adaptive cruise control control than when the driver is gazing ahead; An automatic driving control program that causes at least one computer (10) to function to include the above.

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