Display control device, method, computer program product, and sound control device

Abstract

The invention relates to a display control apparatus, a method, a computer program product and a sound control apparatus. The display control device is provided with: a display control unit (31) for controlling pulse coasting in a display vehicle speed range which is included in the actual vehicle speed range and is narrower than the actual vehicle speed range while the vehicle (10) is subjected to pulse coasting control so as to repeatedly perform acceleration travel and coasting travel in the predetermined actual vehicle speed range; the display vehicle speed is displayed on a display device (15) in such a manner that the display vehicle speed increases during accelerated travel of the vehicle (10) and the display vehicle speed decreases during coasting of the vehicle (10).

Description

Technical Field

[0001] The present invention relates to a display control device, a display control method, and a computer program product for display control that control speed display in a vehicle, and a sound control device that controls sounds generated in a vehicle compartment when the vehicle is performing a specified driving operation. Background Art

[0002] It is known that fuel consumption can be suppressed by a vehicle performing intermittent driving (also referred to as pulse and glide driving) in which acceleration driving and inertial driving are repeatedly performed within a specified actual vehicle speed range. The following technique has been proposed: preventing flickering of speed display caused by speed changes when the vehicle is performing such intermittent driving (see Japanese Patent Application Laid-Open No. 2013-113720).

[0003] In the proposed technique, during intermittent driving of the vehicle, the vehicle display device fixedly displays the restricted vehicle speed, and displays the actual vehicle speed and the acceleration / deceleration state during intermittent driving.

[0004] If the speed display during pulse and glide driving of the vehicle is fixed, since the actual vehicle speed is actually changing, there is a fear that it may give a sense of discomfort to a driver who is sensitive to speed changes due to the difference between the displayed vehicle speed and the actual vehicle speed. Summary of the Invention

[0005] Accordingly, an object of the present invention is to provide a display control device that can reduce flickering of vehicle speed display and a sense of discomfort of a driver during pulse and glide driving of a vehicle.

[0006] A display control device according to one embodiment includes: a display control unit that, during a period in which a vehicle is controlled to perform pulse and glide driving in a manner of repeatedly performing acceleration driving and inertial driving within a specified actual vehicle speed range, displays a display vehicle speed on a display device in such a manner that the display vehicle speed increases during acceleration driving of the vehicle and the display vehicle speed decreases during inertial driving of the vehicle within a display vehicle speed range that is included in the actual vehicle speed range and is narrower than the actual vehicle speed range.

[0007] In one embodiment, the display control device further includes: a determination unit that determines whether a condition for suppressing a driver's gaze at the display device, such as the condition of the surroundings of the vehicle or the actions of the driver of the vehicle, is satisfied, and the display control unit sets the display vehicle speed range to be wider when the gaze suppression condition is satisfied than when the gaze suppression condition is not satisfied.

[0008] In one embodiment, when the pulse and glide driving control ends, the display control unit controls the display device so that the display vehicle speed approaches the actual vehicle speed of the vehicle at a change rate equal to or lower than a specified upper limit change rate.

[0009] A voice control device based on another embodiment includes a voice control unit that, during a pulse glide driving control in which a vehicle is driven in a manner of repeatedly performing acceleration driving and inertial driving within a specified actual vehicle speed range, causes a voice generator mounted on the vehicle to output a simulated acceleration sound inside the vehicle compartment when the vehicle is in inertial driving, where the simulated acceleration sound simulates the sound generated when the vehicle is accelerating.

[0010] In one embodiment, the greater the noise generated during the driving of the vehicle, the more the voice control unit reduces the volume of the simulated acceleration sound.

[0011] A display control method based on yet another embodiment includes: during a pulse glide driving control in which a vehicle is driven in a manner of repeatedly performing acceleration driving and inertial driving within a specified actual vehicle speed range, displaying a display vehicle speed on a display device in such a way that the display vehicle speed increases when the vehicle is accelerating and the display vehicle speed decreases when the vehicle is in inertial driving within a display vehicle speed range that is included in and narrower than the actual vehicle speed range.

[0012] A display control computer program product based on yet another embodiment includes instructions for causing a processor mounted on a vehicle to execute the following processing: during a pulse glide driving control in which a vehicle is driven in a manner of repeatedly performing acceleration driving and inertial driving within a specified actual vehicle speed range, displaying a display vehicle speed on a display device in such a way that the display vehicle speed increases when the vehicle is accelerating and the display vehicle speed decreases when the vehicle is in inertial driving within a display vehicle speed range that is included in and narrower than the actual vehicle speed range.

[0013] The display control device of the present disclosure has an effect of reducing the flicker of the vehicle speed display and the driver's sense of discomfort when the vehicle performs pulse glide driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic configuration diagram of a vehicle equipped with an electronic control device as an example of a display control device or a voice control device.

[0015] Figure 2 It is a functional block diagram of a processor of an ECU related to the display control process based on the first embodiment.

[0016] Figure 3 It is a diagram showing an example of the relationship between the change in the actual vehicle speed and the change in the display vehicle speed when pulse glide driving control is applied to a vehicle.

[0017] Figure 4 It is a flowchart of the operation of the display control process based on the first embodiment.

[0018] Figure 5 It is a functional block diagram of a processor of an ECU related to voice control processing based on a second embodiment.

[0019] Figure 6 It is a diagram showing an example of the relationship between the change in the actual vehicle speed when pulse glide driving control is applied to a vehicle and the output of a simulated acceleration sound.

[0020] Figure 7 It is a flowchart of the operation of voice control processing based on a second embodiment. Detailed Embodiment

[0021] Hereinafter, a display control device, a display control method and a display control computer program executed on the display control device, and a voice control device, a voice control method and a voice control computer program executed on the voice control device will be described with reference to the drawings. During the period in which the vehicle is subjected to pulse glide driving control in such a manner that it repeatedly performs acceleration driving and inertial driving within a specified actual vehicle speed range, the display control device sets the change range of the display vehicle speed (hereinafter referred to as the display vehicle speed range) displayed to the driver to be narrower than the actual vehicle speed range. Further, during the period in which the vehicle is subjected to pulse glide driving control, during inertial driving, the voice control device causes a sound generator to generate a simulated acceleration sound, wherein the simulated acceleration sound simulates the sound generated during acceleration driving. Hereinafter, the pulse glide driving control will be referred to as PG driving control.

[0022] Figure 1 It is a schematic configuration diagram of a vehicle equipped with an electronic control device as an example of a display control device or a voice control device. In the present embodiment, from the viewpoint of improving fuel efficiency due to PG driving control, it is preferable that the vehicle 10 is a vehicle including a motor as a power source in the drive train 11, such as a battery electric vehicle (BEV), a hybrid or a plug-in hybrid vehicle. However, the vehicle 10 may also be a vehicle including only an engine, i.e., a power source other than a motor, in the drive train 11. The vehicle 10 has a vehicle speed sensor 12, an external vehicle sensor 13, a driver monitoring camera 14, a display device 15, a sound generator 16, and an electronic control unit (ECU) 17.

[0023] The vehicle speed sensor 12 measures the speed of the vehicle 10, generates a speed signal representing the speed of the vehicle 10, and outputs the speed signal to the ECU 17.

[0024] The external sensor 13 is a sensor that generates an external sensor signal representing the condition around the vehicle 10. For example, it is an external camera or a ranging sensor such as LiDAR (Light Detection And Ranging) or radar that is configured to be able to photograph the surroundings of the vehicle 10. In the vehicle 10, multiple external sensors 13 with different detectable ranges or types may also be provided. Whenever an external sensor signal is generated, the external sensor 13 outputs the generated external sensor signal to the ECU 17.

[0025] The driver monitoring camera 14 is an example of an in-vehicle sensor, and is mounted on the instrument panel or near it facing the driver in such a way that the head of the driver sitting on the driver's seat of the vehicle 10 is included in the photographing target area of the driver monitoring camera 14. The driver monitoring camera 14 may also have a light source such as an infrared LED (Light Emitting Diode). Also, the driver monitoring camera 14 photographs the driver at every prescribed photographing cycle, thereby generating an image of the driver (hereinafter referred to as a driver image), and outputs the generated driver image to the ECU 17.

[0026] The display device 15 is provided inside the cabin of the vehicle 10. The display device 15 has a display device such as a liquid crystal display or an organic EL (Electroluminescence) display. Moreover, the display device 15 may also have gauges such as a speedometer. The display device 15 is provided inside the cabin of the vehicle 10 facing the driver, for example, on the instrument panel. And, the display device 15 notifies the driver of various information received from the ECU 17 via the in-vehicle network by displaying the information. In the present embodiment, the display device 15 at least displays the vehicle speed of the vehicle 10. It should be noted that the vehicle speed can be displayed in an analog manner or in a digital manner.

[0027] The sound generator 16 outputs a sound corresponding to a control signal from the ECU 17 into the cabin of the vehicle 10. For this purpose, the sound generator 16 has: a generation circuit that generates a sound signal corresponding to the control signal from the ECU 17; and a speaker that outputs a sound corresponding to the sound signal generated by the generation circuit.

[0028] The ECU 17 can execute an automatic driving control process or a driving assistance process for the vehicle 10, where the driving assistance process includes speed control for automatically controlling the vehicle speed of the vehicle 10 such as Adaptive Cruise Control (ACC). And, during the period when the automatic driving control or the vehicle speed control is applied to the vehicle 10, the ECU 17 can execute PG travel control.

[0029] In addition, the ECU 17 is an example of a display control device or a sound control device. During the period when the PG travel control is applied to the vehicle 10, the ECU 17 executes control of vehicle speed display via the display device 15 or control of sound output via the sound generator 16.

[0030] The ECU 17 includes a communication interface 21, a memory 22, and a processor 23. The communication interface 21, the memory 22, and the processor 23 may be configured as separate circuits respectively, or may be integrally configured as an integrated circuit.

[0031] The communication interface 21 has an interface circuit for connecting the ECU 17 to other devices. The communication interface 21 transmits signals from the vehicle speed sensor 12, the external sensor 13, and the driver monitoring camera 14 to the processor 23 respectively. Further, the communication interface 21 outputs a control signal of the drive system 11 received from the processor 23 to the drive system 11. Further, the communication interface 21 outputs a speed display signal received from the processor 23 to the display device 15. Further, in addition, the communication interface 21 outputs a sound control signal received from the processor 23 to the sound generator 16.

[0032] The memory 22 is an example of a storage unit, and includes a volatile semiconductor memory and a non-volatile semiconductor memory. The memory 22 stores various data used in the display control process or the sound control process executed by the processor 23, or various data generated during the display control process or the sound control process. Further, the memory 22 stores various data used in the autonomous driving control or the speed control of the vehicle 10 executed by the processor 23, or various data generated during the autonomous driving control or the speed control.

[0033] The processor 23 includes one or more CPUs (Central Processing Unit) and its peripheral circuits. The processor 23 may further include other arithmetic circuits such as a logic arithmetic unit, a numerical arithmetic unit, or a graphics processing unit. Further, the processor 23 executes a display control process or a sound control process. Further, the processor 23 executes an autonomous driving control or a speed control.

[0034] (First Embodiment)

[0035] Hereinafter, the processing of each part of the processor 23 in the first embodiment will be described. In this embodiment, the ECU 17 functions as a display control device, and during the period when the PG travel control is applied to the vehicle 10, the processor 23 executes a display control process.

[0036] Figure 2It is a functional block diagram of the processor 23 related to the display control process based on the first embodiment. The processor 23 has a display control unit 31, a determination unit 32, and a travel control unit 33. These units of the processor 23 are, for example, functional modules implemented by a computer program operating on the processor 23. Alternatively, these units may also be dedicated arithmetic circuits provided in the processor 23.

[0037] During the period when the PG travel control is applied to the vehicle 10, the display control unit 31 sets a display vehicle speed range that includes the actual vehicle speed range of the vehicle 10 under the PG travel control (hereinafter referred to as the actual vehicle speed range) and is narrower than the actual vehicle speed range. Then, the display control unit 31 calculates the display vehicle speed in such a way that within the display vehicle speed range, the display vehicle speed increases when the vehicle 10 is accelerating and the display vehicle speed decreases when the vehicle 10 is coasting.

[0038] The actual vehicle speed range is set to include the target vehicle speed. The target vehicle speed is set by the driver via an operation device (not shown) provided inside the vehicle compartment. Alternatively, in the case where the vehicle 10 is under autonomous driving control, the target vehicle speed may also be set to the speed limit of the road section in which the vehicle 10 is traveling or a speed obtained by subtracting a prescribed offset from the speed limit. In this case, the display control unit 31 determines the road section in which the vehicle 10 is traveling with reference to the map information and the current position of the vehicle 10. Then, the display control unit 31 may use the speed limit of the determined road section indicated by the map information for setting the target vehicle speed. It should be noted that the map information is pre-stored in the memory 22. Alternatively, the vehicle 10 may additionally have a storage device (not shown) for storing the map information. In addition, the display control unit 31 may set the latest position of the vehicle 10 measured by a receiver (not shown) of a satellite positioning system such as a GPS receiver (Global Positioning System) mounted on the vehicle 10 as the current position of the vehicle 10.

[0039] The actual vehicle speed range can be set, for example, to a speed range of 5% to 10% of the target vehicle speed. In addition, the actual vehicle speed range is set such that the target vehicle speed becomes any speed value within the actual vehicle speed range, for example, the central value, the lower limit value, or the upper limit value of the actual vehicle speed range. In addition, the displayed vehicle speed range can be set, for example, to a range having a width of 30% to 70% of the actual vehicle speed range and including the target vehicle speed. Moreover, the display control unit 31 makes the displayed vehicle speed range when the gaze suppression condition that the driver does not look at the display device 15 is satisfied wider than the displayed vehicle speed range when the gaze suppression condition is not satisfied. For example, the display control unit 31 sets the displayed vehicle speed range when the gaze suppression condition is not satisfied to a range having a width of 50% of the actual vehicle speed range, and sets the displayed vehicle speed range when the gaze suppression condition is satisfied to a range having a width of 70% of the actual vehicle speed range. Thus, in a case where the driver occasionally confirms the displayed vehicle speed, the display control unit 31 makes the displayed vehicle speed close to the actual vehicle speed, thereby further reducing the sense of discomfort felt by the driver when confirming the displayed vehicle speed. It should be noted that whether the gaze suppression condition is satisfied is determined by the determination unit 32. Details of the processing of the determination unit 32 will be described later.

[0040] During the period when the vehicle 10 is subjected to PG driving control by the driving control unit 33, the display control unit 31 calculates the displayed vehicle speed based on the actual vehicle speed of the vehicle 10 measured by the vehicle speed sensor 12. In the present embodiment, the display control unit 31 multiplies the value obtained by subtracting the target vehicle speed from the actual vehicle speed by the ratio of the width of the displayed vehicle speed range to the width of the actual vehicle speed range, thereby calculating the difference between the displayed speed and the target vehicle speed (hereinafter, referred to as the displayed speed residual). Then, the display control unit 31 adds the target vehicle speed to the displayed speed residual, thereby calculating the displayed vehicle speed. For example, assume that the target vehicle speed Vt is 100 km / h, the actual vehicle speed range Rvr is 95 km / h to 105 km / h, and the displayed vehicle speed range Rvd is 97 km / h to 103 km / h. At this time, if the actual vehicle speed Vr is 105 km / h, the displayed vehicle speed Vd is (105 - 100) * (103 - 97) / (105 - 95) + 100 = 103 km / h. The displayed vehicle speed is calculated in this way, so the displayed vehicle speed is included in the displayed vehicle speed range. Moreover, the greater the actual vehicle speed, the greater the displayed vehicle speed. Therefore, when the vehicle 10 is accelerating, as the actual vehicle speed increases, the displayed vehicle speed also increases. On the other hand, when the vehicle 10 is coasting, as the actual vehicle speed decreases, the displayed vehicle speed also decreases.

[0041] Moreover, when the PG travel control ends, the display control unit 31 corrects the displayed vehicle speed so that the displayed vehicle speed approaches the actual vehicle speed of the vehicle 10 at a rate of change equal to or less than a prescribed upper limit rate of change. At this time, it may be that the greater the absolute value of the acceleration or deceleration of the vehicle 10, the greater the upper limit rate of change increased by the display control unit 31. For example, the upper limit rate of change may be set to a value obtained by multiplying the absolute value of the acceleration or deceleration in a recent prescribed period by a prescribed constant (e.g., 1.1 to 1.2). Thereby, it is possible to prevent the displayed vehicle speed from changing abruptly compared to the change in the actual vehicle speed when the PG travel control ends. Therefore, the display control unit 31 can suppress the driver from feeling a sense of discomfort with the change in the displayed vehicle speed immediately after the end of the PG travel control.

[0042] Figure 3 is a diagram showing an example of the relationship between the change in the actual vehicle speed and the change in the displayed vehicle speed when the PG travel control is applied to the vehicle 10. In Figure 3 the horizontal axis represents the elapsed time and the vertical axis represents the speed. And, the curve 301 represents the change in the actual vehicle speed over time, and the curve 302 represents the change in the displayed vehicle speed over time. Moreover, the period P represents the period during which the PG travel control is applied to the vehicle 10.

[0043] As Figure 3 shown, it can be seen that: during the period P in which the PG travel control is applied to the vehicle 10, the actual vehicle speed and the displayed vehicle speed respectively change within a range including the target vehicle speed, and the displayed vehicle speed changes within a displayed vehicle speed range Rvd that is narrower than the actual vehicle speed range Rvr that is the range of change of the actual vehicle speed. Moreover, it can be seen that: as the vehicle 10 accelerates and the actual vehicle speed increases, the displayed vehicle speed also increases, and conversely, as the vehicle 10 coasts and the actual vehicle speed decreases, the displayed vehicle speed also decreases. Thereby, the flicker of the speed display is suppressed, and the sense of discomfort caused by the difference between the actual vehicle speed and the displayed vehicle speed is reduced.

[0044] In addition, as shown by the curve 301 and the curve 302, after the end of the period P, the displayed vehicle speed slowly approaches the actual vehicle speed. Thus, it can be seen that the abrupt change in the displayed vehicle speed is suppressed, and therefore the driver is less likely to feel a sense of discomfort with the change in the displayed vehicle speed.

[0045] The display control unit 31 generates a speed display signal representing the displayed vehicle speed, and outputs the speed display signal to the display device 15 via the communication interface 21, whereby the displayed vehicle speed is displayed on the display device 15.

[0046] The determination unit 32 determines whether the conditions around the vehicle 10 or the actions of the driver of the vehicle 10 satisfy the gaze suppression condition at every prescribed period (e.g., several seconds to several minutes).

[0047] In the present embodiment, when the situation around the vehicle 10 conforms to any one of the following situations, the determination unit 32 determines that the gaze suppression condition is satisfied: a bad weather situation, a situation where the number of other vehicles traveling around the vehicle 10 is equal to or more than a specified number, or a situation where the vehicle 10 is traveling in a curved section.

[0048] For example, when the amount of rain measured by a rain sensor (not shown) provided in the vehicle 10 is more than a specified bad weather threshold, the determination unit 32 determines that the weather around the vehicle 10 is bad weather. Alternatively, it may be that when the operation mode of the windshield wiper of the vehicle 10 is a mode in which the windshield wiper continuously operates, the determination unit 32 determines that the weather around the vehicle 10 is bad weather. Or, in addition, the determination unit 32 can input an out-of-vehicle image generated by an out-of-vehicle camera into a classifier that has been previously learned to identify whether the weather around the vehicle 10 is bad weather, where the out-of-vehicle camera is an example of the out-of-vehicle sensor 13 and is provided to capture the surroundings of the vehicle 10. In this case, the classifier is constituted by, for example, a deep neural network (DNN) having a convolutional neural network (CNN) - type architecture, where the convolutional neural network - type architecture sequentially has one or more convolutional layers and one or more fully - connected layers from the input side. Or, the classifier may also be configured as a classifier based on a machine learning algorithm other than a DNN such as a support vector machine. Such a classifier uses many training images including out-of-vehicle images obtained in a bad weather situation and out-of-vehicle images obtained in a situation that is not bad weather, and is previously learned according to a specified learning algorithm such as the error backpropagation method.

[0049] In addition, in order to count the number of other vehicles traveling around the vehicle 10, the determination unit 32 inputs the out-of-vehicle image into a classifier that has been previously learned to detect other vehicles. Then, the determination unit 32 counts the number of other vehicles detected by the classifier, and if the number of detected other vehicles is equal to or more than a specified number, the determination unit 32 determines that the gaze suppression condition is satisfied. It should be noted that the classifier for detecting other vehicles is configured as a DNN other than a CNN - type DNN, a DNN having an attention mechanism, or a classifier based on a machine learning algorithm other than a DNN such as an adaBoost classifier. Such a classifier also uses many training images including out-of-vehicle images presenting the vehicles to be detected, and is previously learned according to a specified learning algorithm.

[0050] In addition, in order to determine whether the road section where the vehicle 10 is traveling is a curved road section, the determination unit 32 may determine the road section where the vehicle 10 is traveling by referring to the map information and the current position of the vehicle 10 in the same way as the setting of the target vehicle speed in the display control unit 31. Then, if the determined road section represented by the map information is a curved road section, the determination unit 32 determines that the vehicle 10 is traveling in the curved road section, thereby satisfying the gaze suppression condition. Alternatively, the determination unit 32 may detect the lane dividing line by inputting the out-of-vehicle image to a classifier that has been pre-learned in a manner of detecting the lane dividing line. When the curvature when approximating the detected lane dividing line to a curve is equal to or greater than a prescribed curvature, the determination unit 32 determines that the vehicle 10 is traveling in the curved road section. It should be noted that such a classifier may adopt a classifier having the same configuration as the classifier used for detecting other vehicles. Alternatively, the classifier for detecting other vehicles may be pre-learned in a manner of also detecting the lane dividing line.

[0051] In addition, regarding the driver's actions, when the number of times the driver's line of sight is directed toward the display device 15 is equal to or less than a prescribed number during a recent prescribed period (for example, several tens of seconds to several minutes), the determination unit 32 determines that the gaze suppression condition is satisfied. Alternatively, when the ratio of the period during which the driver's line of sight is directed toward other than the display device 15 to the prescribed period is equal to or greater than a prescribed threshold value, the determination unit 32 determines that the gaze suppression condition is satisfied.

[0052] In order to detect the line-of-sight direction of the driver, the determination unit 32 inputs the driver image into a classifier that has been pre-trained to detect the face of the driver from the image, so as to detect the area on the driver image where the eyes of the driver are captured (hereinafter referred to as the eye area). For example, the determination unit 32 may use a DNN with a CNN-based architecture, a support vector machine, or an adaptive boosting classifier as such a classifier. It should be noted that the determination unit 32 may also detect the eye area from the driver image according to other methods of detecting the eye area such as template matching. Moreover, the determination unit 32 detects the corneal reflection image of the light source (hereinafter referred to as the Purkinje image) and the center of gravity of the pupil (hereinafter only referred to as the pupil center of gravity) from the eye area. At this time, the determination unit 32 detects the Purkinje image by matching the template of the Purkinje image with the template of the eye area. Similarly, the determination unit 32 detects the pupil by matching the template of the pupil with the template of the eye area, and the center of gravity of the area representing the detected pupil may be set as the pupil center of gravity. Then, the determination unit 32 calculates the distance between the Purkinje image and the pupil center of gravity, and refers to a table showing the relationship between this distance and the line-of-sight direction of the driver, thereby detecting the line-of-sight direction of the driver. It should be noted that such a table may be pre-stored in the memory 22. Moreover, when the detected line-of-sight direction is included in the display device direction range, the determination unit 32 determines that the line-of-sight direction of the driver is directed towards the display device 15. On the other hand, when the detected line-of-sight direction deviates from the display device direction range, the determination unit 32 determines that the line-of-sight direction of the driver is not directed towards the display device 15, where the display device direction range corresponds to the direction towards the display device 15. It should be noted that the display device direction range may also be pre-stored in the memory 22.

[0053] The determination unit 32 executes the above processing on the latest driver image at every prescribed period (for example, 100 milliseconds to 1 second), thereby obtaining the number of times the line-of-sight direction of the driver is directed towards the display device 15 or the period during which the line-of-sight direction of the driver is directed towards other than the display device 15. That is, the determination unit 32 obtains the sum of each period from the generation time of the driver image when the line-of-sight direction of the driver deviates from the display device direction range to the generation time of the driver image when the line-of-sight direction of the driver becomes included in the display device direction range within the most recent prescribed period as the period during which the line-of-sight direction of the driver is directed towards other than the display device 15. In addition, the determination unit 32 may set the number of times the driver image determined to have the line-of-sight direction of the driver included in the display device direction range is generated within the most recent prescribed period as the number of times the line-of-sight direction of the driver is directed towards the display device 15.

[0054] The determination unit 32 notifies the display control unit 31 of the determination result as to whether the fixation suppression condition is satisfied.

[0055] The driving control unit 33 performs the PG driving control in the application of the autonomous driving control or the speed control of the vehicle 10. In particular, when the vehicle 10 can continue to drive at the target vehicle speed, the driving control unit 33 performs the PG driving control. Specifically, when the distance between the preceding vehicle traveling ahead of the vehicle 10 in the current lane during the driving of the vehicle 10 is greater than the distance threshold at which the vehicle can continue to drive at the target vehicle speed, or when there is no preceding vehicle traveling in the current lane and the vehicle 10 does not need to accelerate or decelerate, the driving control unit 33 performs the PG driving control.

[0056] Therefore, the driving control unit 33 can detect other vehicles traveling around the vehicle 10 and the lane dividing lines in the same manner as described for the determination unit 32 by inputting the out-of-vehicle image, which is an example of the out-of-vehicle sensor signal, into the classifier. Then, the driving control unit 33 can set the area between the two lane dividing lines closest to the vehicle 10 in the out-of-vehicle image as the current lane area corresponding to the current lane. Moreover, the driving control unit 33 can determine the other vehicles among the detected other vehicles that are included in the current lane area at the upper and lower ends in the out-of-vehicle image as the preceding vehicles. When a preceding vehicle is detected, the driving control unit 33 can estimate the distance between the vehicle 10 and the preceding vehicle based on parameters such as the mounting position, shooting direction, and field of view angle of the out-of-vehicle camera, which is an example of the out-of-vehicle sensor 13, and the position of the lower end of the preceding vehicle in the out-of-vehicle image. Alternatively, when a ranging sensor, which is one of the out-of-vehicle sensors 13, is mounted on the vehicle 10, the driving control unit 33 can set the measured value of the distance measured by the ranging sensor with respect to the azimuth of the detected preceding vehicle as the distance between the vehicle 10 and the preceding vehicle.

[0057] Moreover, the driving control unit 33 can determine whether there is a location that requires acceleration or deceleration within a specified distance in the traveling direction of the vehicle 10 based on the map information, the latest position of the vehicle 10 measured by a receiver (not shown) of the satellite positioning system, and the traveling direction of the vehicle 10 measured by an azimuth sensor (not shown) mounted on the vehicle 10. The location that requires deceleration can be set, for example, as a location where a temporary stop line is provided or a location where a toll gate is provided on an expressway. If there is no such location that requires deceleration, the driving control unit 33 determines that there is no need to decelerate the vehicle 10.

[0058] It should be noted that it can be set that the driving control unit 33 performs the PG driving control only when the driver has performed an operation to approve the execution of the PG driving control via an operation device provided in the vehicle interior.

[0059] When the execution of the PG driving control is started, the driving control unit 33 notifies the display control unit 31 of this fact. Then, during the execution of the PG driving control, the driving control unit 33 accelerates the vehicle 10 at a prescribed target acceleration until the actual vehicle speed of the vehicle 10 reaches the upper limit of the actual vehicle speed range. To this end, the driving control unit 33 generates a control signal for controlling the drive system 11 so that the acceleration measured by an acceleration sensor (not shown) mounted on the vehicle 10 approaches the target acceleration. At this time, the driving control unit 33 may generate this control signal according to feedback control such as PID (Proportional-Integral-Derivative) control. Then, the driving control unit 33 outputs the generated control signal to the drive system 11.

[0060] When the actual vehicle speed of the vehicle 10 measured by the vehicle speed sensor 12 reaches the upper limit of the actual vehicle speed range, the driving control unit 33 controls the drive system 11 so that the vehicle 10 coasts. That is, the driving control unit 33 generates a control signal corresponding to the minimum accelerator opening and outputs this control signal to the drive system 11. Then, when the speed of the vehicle 10 measured by the vehicle speed sensor 12 reaches the lower limit of the actual vehicle speed range, the driving control unit 33 controls the drive system 11 so as to accelerate the vehicle 10 at a prescribed target acceleration. Thus, during the application of the PG driving control, the driving control unit 33 controls the drive system 11 such that the actual vehicle speed of the vehicle 10 is included in the actual vehicle speed range and the vehicle 10 alternately repeats accelerating and coasting.

[0061] When the distance between the preceding vehicle and the vehicle 10 in the current lane becomes equal to or less than the distance threshold, or when the distance from the current position of the vehicle 10 to the point where deceleration is required becomes equal to or less than the prescribed distance, the driving control unit 33 ends the PG driving control. Alternatively, it may be that when the driver performs an operation to end the PG driving control via the operation device, or when the driver depresses the accelerator pedal or the brake pedal by a prescribed amount or more, the driving control unit 33 also ends the PG driving control. When the execution of the PG driving control is ended, the driving control unit 33 notifies the display control unit 31 of this fact.

[0062] Figure 4 It is a flowchart of the operation of the display control process based on the first embodiment. During the execution of the PG driving control, the processor 23 executes the display control process according to this flowchart.

[0063] The determination unit 32 determines whether the gaze suppression condition is satisfied (step S101). When the gaze suppression condition is satisfied (step S101 - Yes), the display control unit 31 sets a display vehicle speed range that is narrower than the actual vehicle speed range but relatively wide (step S102). On the other hand, when the gaze suppression condition is not satisfied (step S101 - No), the display control unit 31 sets a display vehicle speed range that is narrower than the actual vehicle speed range but relatively narrow (step S103). Then, the display control unit 31 displays the display vehicle speed on the display device 15 in such a manner that within the display vehicle speed range, the display vehicle speed increases during acceleration and decreases during inertial driving (step S104). Then, the processor 23 repeatedly performs the processing after step S101.

[0064] As described above, during the period when the PG driving control is applied to the vehicle, the display control device according to the first embodiment sets the display vehicle speed range to be narrower than the actual vehicle speed range of the vehicle. Moreover, this display control device displays the display vehicle speed on the display device in such a manner that within the display vehicle speed range, the display vehicle speed increases when the vehicle is accelerating and decreases when it is in inertial driving. Thereby, this display control device makes the change in the display vehicle speed match the change in the actual vehicle speed, and makes the change in the display vehicle speed slower than the change in the actual vehicle speed, thereby reducing the flicker of the display vehicle speed and reducing the driver's sense of discomfort.

[0065] According to the modification example, it may also be that the more times the driver's line of sight direction faces the display device 15 within the most recent specified period, or the smaller the ratio of the period when the driver's line of sight direction faces outside the display device 15 to the most recent specified period, the more the display control unit 31 narrows the display vehicle speed range. In addition, it may also be that regardless of whether the gaze suppression condition is satisfied, the display control unit 31 sets the display vehicle speed range only based on the actual vehicle speed range and the target vehicle speed. In this case, the processing of the determination unit 32 may also be omitted. Therefore, according to this modification example, the computational burden on the processor 23 is reduced.

[0066] (Second Embodiment)

[0067] Next, the processing of each part of the processor 23 in the second embodiment will be described. In this embodiment, the ECU 17 functions as a sound control device. And during the period when the PG driving control is performed on the vehicle 10, the processor 23 executes sound control processing. Hereinafter, the differences from the first embodiment will be described.

[0068] Figure 5It is a functional block diagram of the processor 23 related to the voice control process based on the second embodiment. The processor 23 has a voice control unit 34 and a driving control unit 33. These units of the processor 23 are, for example, functional modules implemented by a computer program operating on the processor 23. Alternatively, these units may also be dedicated arithmetic circuits provided in the processor 23.

[0069] When it is notified from the driving control unit 33 that a transfer to inertial driving has occurred during the execution of the PG driving control, the voice control unit 34 causes the sound generator 16 to output a simulated acceleration sound inside the vehicle compartment of the vehicle 10, where the simulated acceleration sound simulates the sound generated during the acceleration driving of the vehicle 10. Therefore, the acceleration sound data for causing the sound generator 16 to generate the simulated acceleration sound is pre-stored in the memory 22, and during the inertial driving of the vehicle 10, the voice control unit 34 outputs a voice control signal including the acceleration sound data to the sound generator 16. In addition, when it is notified from the driving control unit 33 that a transfer to acceleration driving has occurred during the execution of the PG driving control, the voice control unit 34 stops the output of the voice control signal, thereby stopping the output of the simulated acceleration sound from the sound generator 16.

[0070] It should be noted that the greater the noise during driving, the more difficult it is for the driver to perceive the change in the sound generated by the drive system 11 of the vehicle 10. Therefore, it may also be that the greater the noise generated during the driving of the vehicle 10, the more the voice control unit 34 reduces the volume of the simulated acceleration sound output from the sound generator 16.

[0071] The voice control unit 34 only needs to estimate the degree of noise during the driving of the vehicle 10 based on the actual vehicle speed of the vehicle 10 or the unevenness of the road surface on which the vehicle 10 is traveling. Generally speaking, the faster the actual vehicle speed, the greater the noise during driving. Therefore, the voice control unit 34 controls the sound generator 16 in such a way that the faster the actual vehicle speed of the vehicle 10 measured by the vehicle speed sensor 12, the more the volume of the simulated acceleration sound is reduced.

[0072] In addition, the greater the degree of unevenness of the road surface, the greater the noise during driving. The greater the degree of unevenness of the road surface, the greater the short-term variation amount of the wheel speed measured by the vehicle speed sensor 12 together with the actual vehicle speed. In addition, the greater the degree of unevenness of the road surface, the greater the variation amplitude of the acceleration of the vehicle 10 measured by the acceleration sensor. Therefore, the sound control unit 34 performs FFT (Fast Fourier Transform) on the measured values of the wheel speed within a recent specified period to calculate each frequency component of the wheel speed variation. Then, the sound control unit 34 controls the sound generator 16 in such a manner that the greater the variation component of the wheel speed at a specified frequency (for example, several hundred Hz), the more the volume of the simulated acceleration sound is reduced. Alternatively, the sound control unit 34 may control the sound generator 16 in such a manner that the greater the sum of the absolute values of the variation amounts of the acceleration between each sampling point included in a recent specified period, the more the volume of the simulated acceleration sound is reduced.

[0073] In this way, in a situation where even if the volume of the simulated acceleration sound is reduced, the driver is less likely to notice the reduction in volume, the sound control unit 34 reduces the volume. Therefore, the sound control unit 34 can make it difficult for the driver to know that there is a switch between accelerating driving and inertial driving, and can suppress unnecessary power consumption.

[0074] Figure 6 is a diagram showing an example of the relationship between the change in the actual vehicle speed and the output of the simulated acceleration sound when the PG driving control is applied to the vehicle 10. In Figure 6 the horizontal axis represents the elapsed time. In addition, in the upper graph, the vertical axis represents the volume, and in the lower graph, the vertical axis represents the speed. And, the upper curve 601 represents the time change of the simulated acceleration sound output from the sound generator 16, and the lower curve 602 represents the time change of the actual vehicle speed of the vehicle 10. As Figure 6 shown, during the period when the vehicle 10 is decelerating by inertial driving, the simulated acceleration sound is output. Therefore, the difference between the sound generated during accelerating driving and the sound generated during inertial driving is less likely to be noticed. As a result, the driver is less likely to notice the switch between accelerating driving and inertial driving.

[0075] When the PG driving control is started, the driving control unit 33 notifies the sound control unit 34 of this fact. Thereby, during the execution of the PG driving control, the sound control unit 34 can perform the sound control process. In addition, when transferring from inertial driving to accelerating driving, the driving control unit 33 notifies the sound control unit 34 of this fact. Moreover, when transferring from accelerating driving to inertial driving, the driving control unit 33 notifies the sound control unit 34 of this fact. And, in addition, when the PG driving control is ended, the driving control unit 33 notifies the sound control unit 34 of this fact.

[0076] Figure 7 This is a flowchart of the operation of the voice control process based on the second embodiment. During the execution of the PG driving control, the processor 23 executes the voice control process according to this flowchart.

[0077] The voice control unit 34 determines whether the vehicle 10 is in inertial driving or accelerating driving based on the notification from the driving control unit 33 (step S201). If the vehicle 10 is in inertial driving (step S201 - Yes), the voice control unit 34 sets the volume of the simulated acceleration sound based on the degree of the noise during the driving of the vehicle 10 (step S202). Then, the voice control unit 34 causes the sound generator 16 to output the simulated acceleration sound at the set volume (step S203). On the other hand, if the vehicle 10 is in accelerating driving (step S201 - No), the voice control unit 34 causes the sound generator 16 to stop outputting the simulated acceleration sound (step S204). After step S203 or step S204, the processor 23 repeatedly performs the processing after step S201.

[0078] As described above, during the period when the PG driving control is applied to the vehicle, the voice control device based on the second embodiment causes the sound generator to output the simulated acceleration sound during inertial driving. Therefore, this voice control device can make it difficult for the driver to know the existence of the switching between accelerating driving and inertial driving.

[0079] According to the modification example, it may also be that during the period when the PG driving control is applied to the vehicle 10, even if the vehicle 10 is in accelerating driving, the voice control unit 34 causes the sound generator 16 to output the simulated acceleration sound. However, in this case, preferably, the voice control unit 34 controls the sound generator 16 such that the volume of the simulated acceleration sound during the accelerating driving of the vehicle 10 is smaller than the volume of the simulated acceleration sound during the inertial driving of the vehicle 10. Thereby, it is difficult for the driver to perceive the existence of the switching between accelerating driving and inertial driving.

[0080] The processor 23 of the ECU 17 may also execute the display control based on the first embodiment or its modification example and the voice control based on the second embodiment or its modification example simultaneously. That is, the processor 23 may also have each of the display control unit 31, the determination unit 32, the driving control unit 33, and the voice control unit 34. That is, during the period when the PG driving control is applied to the vehicle 10, the processor 23 sets the displayed vehicle speed range to be narrower than the actual vehicle speed range of the vehicle, and displays the displayed vehicle speed on the display device 15 in such a way that the displayed vehicle speed increases when the vehicle is accelerating and the displayed vehicle speed decreases when it is in inertial driving. Moreover, during the inertial driving of the vehicle 10, the processor 23 causes the simulated acceleration sound to be output from the sound generator 16.

[0081] A computer program that implements the functions of the processor 23 of the ECU 17 based on the above-described embodiments or variations can be provided as a computer program product, for example, in the form of a computer-readable removable recording medium such as a semiconductor memory, a magnetic recording medium, or an optical recording medium.

Claims

1. A display control device, comprising: a display control unit that, during a pulse gliding driving control in which a vehicle is driven in a manner of repeatedly performing acceleration driving and inertial driving within a prescribed actual vehicle speed range, displays a display vehicle speed on a display device in such a manner that the display vehicle speed rises during the acceleration driving of the vehicle and the display vehicle speed falls during the inertial driving of the vehicle within a display vehicle speed range that is included in and narrower than the actual vehicle speed range.

2. The display control device according to claim 1, further comprising: a determination unit that determines whether a condition around the vehicle or an action of a driver of the vehicle satisfies a gaze suppression condition for the driver not to gaze at the display device, wherein the display control unit sets the display vehicle speed range in a case where the gaze suppression condition is satisfied to be wider than the display vehicle speed range in a case where the gaze suppression condition is not satisfied.

3. The display control device according to claim 1 or 2, wherein: when the pulse gliding driving control ends, the display control unit causes the display vehicle speed to approach the actual vehicle speed of the vehicle at a change rate equal to or lower than a prescribed upper limit change rate.

4. A sound control device, comprising: A sound control unit outputs, inside a vehicle compartment of the vehicle, a simulated acceleration sound from a sound generator mounted on the vehicle while the vehicle is coasting, during a period in which the vehicle is controlled to perform pulse gliding driving in such a way that the vehicle repeatedly performs acceleration driving and coasting driving within a specified actual vehicle speed range, where The simulated acceleration sound simulates the sound generated when the vehicle is performing the acceleration driving.

5. The sound control device according to claim 4, wherein: the greater the noise generated during the driving of the vehicle, the more the sound control unit reduces the volume of the simulated acceleration sound.

6. A display control method, comprising: during a pulse gliding driving control in which a vehicle is driven in a manner of repeatedly performing acceleration driving and inertial driving within a prescribed actual vehicle speed range, displaying a display vehicle speed on a display device in such a manner that the display vehicle speed rises during the acceleration driving of the vehicle and the display vehicle speed falls during the inertial driving of the vehicle within a display vehicle speed range that is included in and narrower than the actual vehicle speed range.

7. A computer program product for display control, comprising instructions for causing a processor mounted on a vehicle to execute the following process: during a pulse gliding driving control in which the vehicle is driven in a manner of repeatedly performing acceleration driving and inertial driving within a prescribed actual vehicle speed range, displaying a display vehicle speed on a display device in such a manner that the display vehicle speed rises during the acceleration driving of the vehicle and the display vehicle speed falls during the inertial driving of the vehicle within a display vehicle speed range that is included in and narrower than the actual vehicle speed range.

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