Vehicle driving control device, method, and program

Abstract

To early terminate override control as desired by a driver.SOLUTION: A vehicle travel control apparatus 100 includes: a driving control device 26 for controlling driving force of a vehicle 102; a braking control device 36 for applying braking force to wheels 34; and a driving support ECU 10 for executing vehicle speed limit control to execute limitation on the driving force by controlling the driving control device when a vehicle speed exceeds a limit vehicle speed. When an accelerator opening ACC is increased by a driver during execution of the vehicle speed limit control, the driving support ECU executes override control to cancel execution of the limitation on the driving force, until the vehicle speed becomes equal to or lower than the limit vehicle speed. The driving support ECU decelerates the vehicle by controlling the braking control device when a time during which the accelerator opening is 0 becomes equal to or longer than a reference time during execution of the override control.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a driving control device, method, and program applied to vehicles such as automobiles.

Background Art

[0002] As driving control in vehicles such as automobiles, when the vehicle speed exceeds the restricted speed (set speed), speed limit control for restricting the driving force of the vehicle is known. Further, when a predetermined driving operation is performed by the driver during the restriction of the driving force by the speed limit control, override control for releasing the restriction of the driving force is executed to allow the vehicle speed to become higher than the restricted speed, and when the vehicle speed becomes lower than the restricted speed, it is also known to end the override control.

[0003] For example, the following Patent Document 1 related to the application of the applicant of the present application describes an example of a speed limit device configured to perform speed limit control and override control.

Prior Art Document

Patent Document

[0004]

Patent Document 1

Summary of the Invention

[0005] 〔Problems to be Solved by the Invention〕 In a conventional driving control device that performs speed limit control and override control, the override control ends when the driving operation amount is reduced by the driver and the vehicle speed becomes lower than the restricted speed. In a situation where the override control is being executed, even if the driver tries to lower the vehicle speed and reduces the driving operation amount until, for example, the accelerator opening becomes 0, the vehicle speed is only reduced by engine braking or the like, so it takes time until the vehicle speed becomes lower than the restricted speed. Therefore, there are cases where the override control cannot be ended early as desired by the driver.

[0006] Furthermore, if the driver wishes to terminate the override control, they must switch from driving with the accelerator pedal to braking with the brake pedal, which can be cumbersome for the driver.

[0007] The present invention provides a driving control device, method, and program that can terminate override control during vehicle speed limit control earlier than conventional methods, without transitioning the driving operation from driving operation to braking operation. [Means for solving the problem and the effects of the invention]

[0008] According to the present invention, a vehicle driving control device (100) is provided, which includes a drive control device (26) that controls the driving force of a vehicle (102) in accordance with at least the accelerator opening (ACC), a braking control device (36) that decelerates the vehicle by applying braking force to the wheels (34), and a control unit (driving support ECU 10) that controls the drive control device to limit the driving force when the vehicle speed (V) exceeds the limit vehicle speed (Vlim) (S150, S170), wherein the control unit is configured to perform override control (S20, S140, S150) that releases the limit on the driving force when the accelerator opening is increased by the driver while the vehicle speed limit control is being performed (S10), until the vehicle speed falls below the limit vehicle speed (S80).

[0009] The control unit (driving support ECU 10) is configured to decelerate the vehicle by controlling the braking control device (36) when the time (T) during which the accelerator opening is 0 exceeds a reference time (Tc) (S30, S50, S60) while override control is being performed.

[0010] Furthermore, the present invention provides a vehicle driving control method applicable to a vehicle equipped with at least a drive control device (26) that controls the driving force of the vehicle (102) according to the accelerator opening (ACC), and a braking control device (36) that decelerates the vehicle by applying braking force to the wheels (34), and includes the steps of: executing speed limit control (S150, S170) which controls the drive control device to limit the driving force when the vehicle speed (V) exceeds the limit vehicle speed (Vlim); and executing override control (S20, S140, S150) which, when the accelerator opening is increased by the driver during the execution of speed limit control (S10), releases the limit on the driving force until the vehicle speed falls below the limit vehicle speed (S80).

[0011] The driving control method further includes a step (S70) in which, when override control is being performed, if the time (T) during which the accelerator opening is 0 is equal to or greater than a reference time (Tc) (S30, S50, S60), the vehicle is decelerated by controlling the braking control device (36).

[0012] Furthermore, according to the present invention, a driving control program is provided which causes an electronic control unit (driving support ECU 10) mounted on a vehicle to execute the following steps when the vehicle speed (V) exceeds a speed limit (Vlim): a drive control device (26) that controls the driving force of the vehicle (102) according to the accelerator opening (ACC), and a brake control device (36) that decelerates the vehicle by applying braking force to the wheels (34).

[0013] The driving control program further includes a step (S70) in which, when override control is being performed, if the time (T) during which the accelerator opening (ACC) is 0 is equal to or greater than a reference time (Tc) (S30, S50, S60), the braking control device (36) is controlled to decelerate the vehicle.

[0014] According to the above-described driving control device, method, and program, when override control is being performed, if the time during which the accelerator opening is 0 exceeds a reference time, the braking control device is activated to decelerate the vehicle. Therefore, compared to conventional driving control devices that decelerate the vehicle using engine braking, the vehicle deceleration can be increased, and the override control during speed limit control can be terminated earlier.

[0015] Furthermore, the driving operation only needs to be maintained in an accelerator-off state so that the time the accelerator opening is 0 is longer than the standard time; braking operation is not required. Therefore, the driver does not need to switch driving operations from driving operations on the accelerator pedal to braking operations on the brake pedal in order to terminate the override control as desired, thus reducing the likelihood of the driver experiencing inconvenience. [Aspects of the Invention]

[0016] In one embodiment of the present invention, when override control is being performed, the control unit (driving support ECU 10) is configured to calculate the target deceleration of the vehicle (Gbt) so that it gradually increases from the vehicle's deceleration at the point when the time during which the accelerator opening (ACC) is 0 becomes 0 (Tc) or greater than or equal to a reference time (Tc) (S70), and to decelerate the vehicle by controlling the braking control device (36) so that the vehicle's deceleration (Gb) becomes the target deceleration (S70, S230, S250, S260).

[0017] According to the above embodiment, the target deceleration of the vehicle is calculated to gradually increase from the vehicle's deceleration at the point when the time with the accelerator opening at 0 exceeds a reference time, and the vehicle is decelerated by controlling the braking control device so that the vehicle's deceleration reaches the target deceleration. Therefore, when the vehicle deceleration begins due to the control of the braking control device, it is possible to prevent a sudden change in the vehicle's deceleration and the resulting discomfort felt by the vehicle's occupants.

[0018] In another embodiment of the present invention, the control unit (driving support ECU 10) is configured to calculate the target deceleration (Gbt) of the vehicle so as to gradually increase up to a preset maximum target deceleration (S70).

[0019] According to the above embodiment, the vehicle's target deceleration is calculated to gradually increase up to a preset maximum target deceleration. Therefore, it is possible to prevent the vehicle's target deceleration from changing abruptly and the resulting abrupt change in the vehicle's deceleration, and also to prevent the vehicle's target deceleration from becoming excessive and the resulting excessive deceleration of the vehicle.

[0020] In the above description, to aid in understanding the present invention, the names and / or reference numerals used in the embodiments of the invention corresponding to those embodiments described later are indicated in parentheses. However, the components of the present invention are not limited to the components of the embodiments corresponding to the names and / or reference numerals indicated in parentheses. Other objects, other features and incidental advantages of the present invention will be readily apparent from the description of embodiments of the present invention, which will be described with reference to the following drawings. [Brief explanation of the drawing]

[0021] [Figure 1] This is a schematic diagram showing an embodiment of a vehicle driving control device according to the present invention. [Figure 2] This is a flowchart corresponding to the override control program. [Figure 3]It is a flowchart corresponding to a driving force control program for vehicle speed limit. [Figure 4] It is a flowchart corresponding to a braking force control program. [Figure 5] It is a diagram showing an example of the operation of the embodiment.

Mode for Carrying Out the Invention

[0022] The traveling control device according to an embodiment of the present invention will be described in detail below with reference to the attached drawings.

[0023] As shown in FIG. 1, the traveling control device 100 according to an embodiment of the present invention is applied to a vehicle 102 and includes a driving support ECU 10. The vehicle 102 is a vehicle capable of autonomous driving and includes a driving ECU 20, a braking ECU 30, and a meter ECU 50. ECU means an electronic control unit (Electronic Control Unit) having a microcomputer as a main part.

[0024] The microcomputer of each ECU includes a CPU, a ROM, a RAM, a readable and writable non-volatile memory (N / M), an interface (I / F), and the like. The CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. Further, these ECUs are connected to each other via a CAN (Controller Area Network) 104 so as to be able to exchange data (communicate). Therefore, the detection values of sensors (including switches) connected to a specific ECU are also transmitted to other ECUs.

[0025] The driving support ECU 10 is a central control device that performs driving support traveling control such as vehicle speed limit control, following vehicle distance control, and lane keeping control. In the embodiment, the driving support ECU 10 cooperates with other ECUs to execute traveling control for the vehicle 102, as will be described in detail later.

[0026] In this embodiment, the driver assistance ECU 10 sets a speed limit Vlim, and when it determines that the vehicle speed V of the vehicle 102 exceeds the speed limit Vlim, it executes speed limit control to automatically limit the driving force of the vehicle so that the vehicle speed remains below the speed limit. Furthermore, if a driving operation that overrides the automatic limiting of the driving force is performed while the speed limit control is being executed, the automatic limiting of the driving force is released. Thus, the driving control device 100 functions as an Adjustable Speed ​​Limiter (ASL).

[0027] The driver assistance ECU 10 is connected to a camera sensor 12, a radar sensor 14, and a setting control unit 16. The camera sensor 12 and radar sensor 14 each include multiple camera devices and multiple radar devices, respectively. The camera sensor 12 and radar sensor 14 function as a target information acquisition device 18 that acquires target information around the vehicle 102.

[0028] Each camera device of the camera sensor 12, although not shown in the figure, includes a camera unit that photographs the area around the vehicle 102 and a recognition unit that analyzes the image data obtained from the camera unit to recognize landmarks such as road lines and road signs (including road surface markings). The recognition unit supplies information about the recognized landmarks to the driver assistance ECU 10 at predetermined intervals. When the information about road signs supplied from the camera sensor 12 is information about a road sign indicating a speed limit, the driver assistance ECU 10 determines the speed limit Vlimc based on this information.

[0029] Each radar device of the radar sensor 14 is equipped with a radar transceiver and a signal processing unit (not shown). The radar transceiver emits millimeter-wave radio waves (hereinafter referred to as "millimeter waves") and receives millimeter waves (i.e., reflected waves) reflected by three-dimensional objects (e.g., other vehicles, bicycles, etc.) within the emission range. The signal processing unit supplies information representing the distance between the vehicle and the three-dimensional object, the relative speed between the vehicle and the three-dimensional object, and the relative position (direction) of the three-dimensional object to the vehicle at predetermined intervals, based on the phase difference between the transmitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time from the transmission of the millimeter waves to the reception of the reflected waves. LiDAR (Light Detection And Ranging) may be used instead of or in addition to the radar sensor 14.

[0030] The setting control unit 16 is located in a position that can be operated by the driver, similar to a steering wheel (not shown in Figure 1), and is operated by the driver. Although not shown in Figure 1, the setting control unit 16 includes an ASL control unit 16A that functions as a speed limit setting device. The driver assistance ECU 10 performs speed limit control when the main switch of the ASL control unit 16A is turned on, as will be described in detail later. The ASL control unit 16A is configured to change and set the speed limit Vlima when a button is operated. For details of the ASL control unit, please refer to, for example, Japanese Patent Application Publication No. 2017-1406, filed by the applicant of this application, if necessary.

[0031] The drive ECU 20 is connected to a drive unit 22 that accelerates the vehicle 102 by applying driving force to the drive wheels 24. Normally, the drive ECU 20 controls the drive unit 22 so that the driving force generated by the drive unit 22 changes in accordance with the driver's driving operation, and when it receives a command signal from the driver assistance ECU 10, it controls the drive unit 22 based on the command signal. Therefore, the drive ECU 20 and the drive unit 22 work together to function as a drive control device 26.

[0032] The drive system may be any drive system known in the art, such as an engine and transmission, an engine and motor combination (a so-called hybrid system), a plug-in hybrid system, a fuel cell and motor combination, or a motor.

[0033] The braking ECU 30 is connected to a braking device 32 that decelerates the vehicle 102 by applying braking force to the wheels 34. Normally, the braking ECU 30 controls the braking device 32 so that the braking force generated by the braking device 32 changes in accordance with the braking operation by the driver. When it receives a command signal from the driver assistance ECU 10, it performs automatic braking by controlling the braking device 32 based on the command signal.

[0034] Therefore, the braking ECU 30 and the braking device 32 work together to function as a braking control device 36. Note that when braking force is applied to the wheels due to vehicle speed limit control or other reasons, brake lights (not shown in Figure 1) illuminate.

[0035] A touch-panel display unit 52 is connected to the meter ECU 50 to display the status of control by the driver assistance ECU 10 and other information. The display unit 52 may be, for example, a multi-information display that displays meters and various other information, or it may be the display of the navigation device 80 described later. As described later, when the display unit 52 receives a signal from the driver assistance ECU 10, it displays the status of the vehicle speed limit control, the limited vehicle speed Vlim, etc.

[0036] The driving operation sensor 60 and the vehicle condition sensor 70 are also connected to CAN 104. Information detected by the driving operation sensor 60 and the vehicle condition sensor 70 (referred to as sensor information) is transmitted to CAN 104. The sensor information transmitted to CAN 104 can be used as appropriate by each ECU. Note that the sensor information may be information from a sensor connected to a specific ECU and transmitted to CAN 104 from that specific ECU.

[0037] The driving operation sensor 60 includes an accelerator opening sensor 60A that detects the accelerator opening ACC, which is the drive operation amount; a braking operation amount sensor that detects master cylinder pressure or the force applied to the brake pedal; and a brake switch that detects whether or not the brake pedal is operated. The driving operation sensor 60 also includes a kickdown switch 60B. The kickdown switch 60B switches on when the accelerator opening ACC is equal to or greater than a starting reference value (a positive constant), and switches off when the accelerator opening ACC is equal to or less than a stopping reference value (a positive constant smaller than the starting reference value). Furthermore, the driving operation sensor 60 includes a steering angle sensor that detects the steering angle, a steering torque sensor that detects the steering torque, and the like.

[0038] The vehicle condition sensor 70 includes a vehicle speed sensor for detecting the vehicle speed V of the vehicle 102, a longitudinal acceleration sensor for detecting the acceleration of the vehicle in the longitudinal direction, a lateral acceleration sensor for detecting the acceleration of the vehicle in the lateral direction, and a yaw rate sensor for detecting the yaw rate of the vehicle.

[0039] Furthermore, a navigation device 80 is also connected to CAN 104. The navigation device 80 includes a GPS receiver for detecting the position of the vehicle 102, a storage device for storing map information and road information, and a communication device for acquiring the latest map information and road information from an external source. In particular, the road information includes information on the speed limit Vlimn. Based on the vehicle's position on the map and the road information, the navigation device 80 extracts information on the speed limit Vlimn, which represents the speed limit on the road the vehicle is currently traveling on, and outputs the extracted speed limit information to the driver assistance ECU 10 via CAN 104. Note that the navigation device 80 is not required.

[0040] The driver assistance ECU 10 sets the vehicle speed limit Vlim based on the vehicle speed limit Vlimc set based on the road sign information supplied from the camera sensor 12, the vehicle speed limit Vlima set by the ASL operator, and the vehicle speed limit Vlimn extracted by the navigation device 80. For example, the vehicle speed limit Vlim may be set by selecting one of Vlimc, Vlima, and Vlimn according to a predetermined priority order.

[0041] In this embodiment, the ROM of the driver assistance ECU 10 stores an override control program and a drive force control program for vehicle speed limiting, respectively, corresponding to the flowcharts shown in Figures 2 and 3. Furthermore, the ROM of the braking ECU 30 stores a braking force control program for vehicle speed limiting, corresponding to the flowchart shown in Figure 4.

[0042] The vehicle driving control method in the embodiment is performed by executing override control, driving force control for vehicle speed limiting, and braking force control for vehicle speed limiting according to the flowcharts shown in Figures 2 to 4. <Override control (Figure 2)>

[0043] Next, the override control in the embodiment will be described with reference to the flowchart shown in Figure 2. The override control according to the flowchart shown in Figure 2 is repeatedly executed at predetermined intervals by the CPU of the driver support ECU 10 when the main switch of the ASL operator 16A is ON. Note that the flag For is initialized to 0 when the override control starts.

[0044] First, in step S10, the CPU determines whether the kickdown switch 60B is on, that is, whether the accelerator pedal opening ACC has reached or exceeded the starting reference value. If a negative determination is made, the override control is terminated; if a positive determination is made, the override control proceeds to step S20.

[0045] In step S20, the CPU sets the flag For to 1 and resets the elapsed time T since the accelerator opening ACC became 0% to 0.

[0046] In step S30, the CPU determines whether the accelerator pedal opening (ACC) is 0%, that is, whether the accelerator is off. If a negative determination is made, the override control terminates temporarily; if a positive determination is made, the override control proceeds to step S40.

[0047] In step S40, the CPU determines whether or not the driver has performed a braking operation. If the determination is positive, the override control proceeds to step S80; if the determination is negative, the override control proceeds to step S50.

[0048] In step S50, the CPU increments ΔT, which is the elapsed time T since the accelerator opening ACC became 0%. ΔT is the cycle time (a positive constant) of the override control according to the flowchart shown in Figure 2.

[0049] In step S60, the CPU determines whether the elapsed time T is greater than or equal to a reference value Tc (a positive constant such as 3 seconds), that is, whether or not to start decelerating the vehicle 102 by automatic braking. If a negative determination is made, the override control returns to step S30; if a positive determination is made, the override control proceeds to step S70.

[0050] In step S70, the CPU increments the target deceleration Gbt of the vehicle 102 by ΔGb (a negative constant) and outputs an automatic braking command signal to the braking ECU 30 based on the target deceleration Gbt. Note that the target deceleration Gbt is a negative value because it is the target value of negative acceleration. Furthermore, if the target deceleration Gbt exceeds the maximum value of the deceleration Gbtmax (a negative constant) due to the increment, it is limited to the maximum value Gbtmax.

[0051] In step S80, the CPU determines whether the vehicle speed V is less than or equal to the vehicle speed limit Vlim. If the determination is negative, the override control returns to step S30; if the determination is positive, the override control proceeds to step S90.

[0052] In step S90, the CPU resets the For flag to 0 and then terminates the override control. <Drive force control for vehicle speed limiting (Figure 3)>

[0053] Next, we will explain the drive force control for vehicle speed limiting by referring to the flowchart shown in Figure 3. The drive force control for vehicle speed limiting according to the flowchart shown in Figure 3 is also repeatedly executed at predetermined intervals by the CPU of the driver assistance ECU 10 when the main switch of the ASL operator 16A is ON.

[0054] In step S110, the CPU calculates the driver's requested driving force Fdd based on the accelerator pedal opening ACC in a manner known in the art.

[0055] In step S120, the CPU calculates the limiting driving force Fdlim of the vehicle 102 to limit the vehicle speed V to less than or equal to the limiting vehicle speed Vlim, based on the current vehicle speed V, the limiting vehicle speed Vlim, and the current acceleration, in a manner known in the art.

[0056] In step S130, the CPU determines whether the requested driving force Fdd is greater than the limiting driving force Fdlim, that is, whether it is necessary to limit the driving force by the limiting driving force Fdlim. If a negative determination is made, the driving force control proceeds to step 150; if a positive determination is made, the driving force control proceeds to step S140.

[0057] In step S140, the CPU determines whether the flag For is 1, that is, whether an override is in progress to release the limit on the driving force. If a positive determination is made, in step S150, the target driving force Fdt of the vehicle 102 is set to the requested driving force Fdd. If a negative determination is made, in step S160, the target driving force Fdt of the vehicle 102 is set to the limiting driving force Fdlim.

[0058] In step S170, the CPU outputs a command signal to the drive ECU 20 to set the driving force Fd of the vehicle 102 to the target driving force Fdt. As a result, the drive unit 22 is controlled by the drive ECU 20 so that the driving force Fd of the vehicle 102 becomes the target driving force Fdt.

[0059] Therefore, when the requested driving force Fdd is greater than the limiting driving force Fdlim and the flag For is 0, the target driving force Fdt is set to the limiting driving force Fdlim, and the driving force Fd of the vehicle 102 is controlled to become the limiting driving force Fdlim. In contrast, even if the requested driving force Fdd is greater than the limiting driving force Fdlim, if the flag For is 1 and the system is in override mode, the target driving force Fdt is set to the requested driving force Fdd, and the driving force Fd of the vehicle 102 is controlled to become the requested driving force Fdd, without being limited by the limiting driving force Fdlim. <Braking force control for vehicle speed limiting (Figure 4)>

[0060] Next, we will explain the braking force control for vehicle speed limiting by referring to the flowchart shown in Figure 4. The braking force control for vehicle speed limiting according to the flowchart shown in Figure 4 is repeatedly executed at predetermined intervals by the CPU of the braking ECU 30 when the ignition switch (not shown in Figure 1) is ON.

[0061] In step S210, the CPU determines whether the main switch of the ASL operator 16A is on or off. If the determination is positive, the braking force control proceeds to step S240; if the determination is negative, the braking force control proceeds to step S220.

[0062] In step S220, the CPU determines whether or not the driver is performing a braking operation. If the determination is positive, the braking force control proceeds to step S240; if the determination is negative, the braking force control proceeds to step S230.

[0063] In step S230, the CPU determines whether or not an automatic braking command signal based on the target deceleration Gbt has been input from the driver assistance ECU 10. If a negative determination is made, the braking force control proceeds to step S240; if a positive determination is made, the braking force control proceeds to step S250.

[0064] In step S240, the CPU controls the braking device 32 based on the braking operation amount detected by the braking operation amount sensor of the driving operation sensor 60. For example, the CPU calculates the target braking force Fbt of the vehicle 102 based on the braking operation amount in a manner known in the art, calculates the target braking force for each wheel based on the target braking force Fbt, and controls the braking device 32 so that the braking force of each wheel becomes the corresponding target braking force.

[0065] In step S250, the CPU calculates the target braking force for each wheel in a manner known in the art, based on the target deceleration Gbt calculated in step S70 and input from the driving support ECU 10.

[0066] In step S260, the CPU controls the braking control device 36 so that the braking force of each wheel corresponds to the target braking force. This causes the vehicle to decelerate through automatic braking during the override. <Operation and Effects of the Embodiment>

[0067] Next, with reference to Figure 5, a vehicle speed limit control in the embodiment will be described as an example of the operation of the embodiment. The second row of Figure 5 shows the change in acceleration of the vehicle 102, and negative values ​​of acceleration indicate the vehicle's deceleration Gb.

[0068] As shown in Figure 5, assume that immediately before time t1, the driver suddenly pressed the brake pedal, and at time t1, the kickdown switch 60B was turned on. In step S10, a positive determination was made, and in step S20, the flag For was set to 1, and override control was started. The vehicle speed V and acceleration changed according to the accelerator opening ACC, and the vehicle speed V became a value higher than the limited vehicle speed Vlim.

[0069] At time t2, the driver begins to reduce the pressure on the brake pedal, causing the accelerator pedal position (ACC) to start decreasing from 100%. At time t3, the accelerator pedal position (ACC) decreases to 0%, and the judgment in step S30 becomes positive. From time t3 onward, the vehicle is decelerated by engine braking, and the vehicle speed V gradually decreases.

[0070] Assume that at time t4, the elapsed time from time t3 is equal to or greater than the reference elapsed time Tc, and the judgment in step S60 is affirmative. Assume that the target deceleration Gbt of vehicle 102 increases from time t4 to time t5, and reaches its maximum value Gbtmax at time t5. Since the vehicle is decelerated by automatic braking based on the target deceleration Gbt from time t4 onward, the degree of decrease in vehicle speed V from time t4 onward is greater than the degree of decrease from time t3 to time t4.

[0071] If, at time t6, the vehicle speed V becomes less than or equal to the speed limit Vlim, and the judgment in step S80 is positive, then in step S90, the flag For is reset to 0, and the override control ends. In step S130, a negative judgment is made, and step S150 is executed, causing the deceleration Gb of vehicle 102 to decrease from its maximum value Gbtmax. The vehicle speed V becomes slightly lower than the speed limit Vlim, then increases, and for example, at time t7, it becomes the speed limit Vlim.

[0072] In conventional driving control systems, when the accelerator pedal opening (ACC) is 0%, the vehicle is decelerated by engine braking, and even if the elapsed time from time t3 exceeds the reference elapsed time Tc, no deceleration by automatic braking is performed. Therefore, as shown by the dashed line in Figure 5, the vehicle speed V decreases at the same rate from time t4 onward as it did from time t3 to time t4. Consequently, the vehicle speed V becomes below the speed limit Vlim at time t8, and override control continues from time t1 to time t8, requiring a long time for the vehicle speed V to decrease below the speed limit Vlim.

[0073] In contrast, according to this embodiment, the vehicle speed V decreases to below the limited vehicle speed Vlim at time t6, which is much earlier than time t8. Therefore, the override control during vehicle speed limit control ends earlier than in the conventional method.

[0074] As can be seen from the above explanation, according to the driving control device, method, and program of the present invention, when override control is being performed, if the time T during which the accelerator opening ACC is 0% is equal to or greater than the reference time Tc (S30, S50, S60), the braking control device 36 is controlled and the vehicle 102 is automatically decelerated (S70). Therefore, compared to conventional driving control devices in which the vehicle is decelerated by engine braking, the vehicle deceleration Gb can be increased and the override control during vehicle speed limit control can be terminated earlier.

[0075] Furthermore, the driving operation only needs to be maintained in an accelerator-off state so that the time T during which the accelerator opening ACC is 0% is equal to or greater than the reference time Tc; braking operation is not required. Therefore, the driver does not need to switch driving operations from driving operations on the accelerator pedal to braking operations on the brake pedal in order to terminate the override control as desired, thus reducing the likelihood of the driver experiencing inconvenience.

[0076] In particular, according to the embodiment, the target deceleration Gbt of the vehicle 102 is calculated to gradually increase from the vehicle's deceleration at the point when the time T during which the accelerator opening ACC is 0% is equal to or greater than the reference time Tc (S70), and the vehicle is decelerated by controlling the braking control device 36 so that the vehicle's deceleration Gb reaches the target deceleration (S70, S230, S250, S260). Therefore, when the vehicle deceleration begins due to the control of the braking control device, it is possible to prevent a sudden change in the vehicle's deceleration and the resulting discomfort felt by the vehicle's occupants.

[0077] Furthermore, according to the embodiment, the target deceleration Gbt of the vehicle 102 is calculated to gradually increase up to a preset maximum target deceleration Gbtmax (S70). Therefore, it is possible to prevent the vehicle's target deceleration from changing abruptly and the resulting abrupt change in the vehicle's deceleration Gb, and also to prevent the vehicle's target deceleration from becoming excessive and the resulting excessive deceleration of the vehicle.

[0078] Furthermore, according to the embodiment, the speed limit Vlim is variably set based on the speed limit Vlimc, which is set based on road sign information, the speed limit Vlima, which is set by the ASL operator, and the speed limit Vlimn, which is extracted by the navigation device 80. Therefore, the speed limit Vlim can be automatically set according to the speed limit of the road on which the vehicle is traveling. In addition, the driver can variably set the speed limit Vlimn according to their own will.

[0079] Although the present invention has been described in detail above with respect to specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited to the embodiments described above, and that various other embodiments are possible within the scope of the present invention.

[0080] For example, in the above embodiment, the speed limit Vlim is variably set based on the speed limit Vlimc, which is set based on road sign information; the speed limit Vlima, which is set by the ASL operator; and the speed limit Vlimn, which is extracted by the navigation device 80. However, the speed limit Vlim may also be a preset constant.

[0081] Furthermore, in the above-described embodiment, the speed limit Vlim is set variably based on the speed limits Vlimc, Vlima, and Vlimn. However, at least one of the following can be omitted: the variable setting of the speed limit Vlimc based on road sign information, the variable setting of the speed limit Vlimc based on Vlima road sign information by the ASL operator, and the variable setting of Vlimn by the navigation device 80.

[0082] Furthermore, in the above-described embodiment, the driving operation sensor 60 includes a kickdown switch 60B, and override control is started when the kickdown switch is ON (S10, S20). However, the kickdown switch may be omitted, and in step S10, it may be determined whether or not the accelerator opening ACC is equal to or greater than the starting reference value, and override control may be started when a positive determination is made.

[0083] Furthermore, in the above-described embodiment, in step S60, it is determined whether or not to start deceleration of the vehicle 102 by automatic braking based on whether or not the elapsed time T is equal to or greater than a reference value Tc, and the reference value Tc is a positive constant. However, the reference value Tc may be variably set according to the vehicle speed so that deceleration by automatic braking starts earlier as the vehicle speed V increases.

[0084] Furthermore, in the above-described embodiment, in step S70, the target deceleration Gbt of the vehicle 102 is incremented by ΔGb, and the increment amount ΔGb is a negative constant. However, the increment amount ΔGb may be variably set according to the vehicle speed such that the absolute value increases with increasing vehicle speed, so that the deceleration due to automatic braking increases as the vehicle speed V increases. [Explanation of symbols]

[0085] 10…Driver assistance ECU, 12…Camera sensor, 14…Radar sensor, 18…Target information acquisition device, 26…Drive control device, 36…Brake control device, 36…Automatic braking device, 60A…Accelerator position sensor, 60B…Kickdown switch, 100…Driving control device, 102…Vehicle

Claims

1. A vehicle driving control device comprising: a drive control device that controls the driving force of the vehicle in accordance with at least the accelerator opening; a braking control device that decelerates the vehicle by applying braking force to the wheels; and a control unit that controls the drive control device to limit the driving force when the vehicle speed exceeds the speed limit, wherein the control unit is configured to perform override control to release the limit on the driving force when the accelerator opening is increased by the driver while the speed limit control is being performed, until the vehicle speed falls below the speed limit, The control unit is configured to decelerate the vehicle by controlling the braking control device when the time during which the accelerator opening is 0 exceeds a reference time while the override control is being performed.

2. A vehicle driving control device according to claim 1, wherein the control unit is configured to decelerate the vehicle by, when the accelerator opening is zero for a period of time equal to or greater than a reference time while the override control is being performed, calculating a target deceleration of the vehicle so as to gradually increase from the deceleration of the vehicle at the point when the accelerator opening is zero for a period of time equal to or greater than a reference time, and controlling the braking control device so that the deceleration of the vehicle reaches the target deceleration.

3. A vehicle driving control device according to claim 1, wherein the control unit is configured to calculate the target deceleration of the vehicle so as to gradually increase up to a preset maximum target deceleration.

4. A vehicle driving control method applicable to a vehicle equipped with at least a drive control device that controls the driving force of the vehicle according to the accelerator opening, and a braking control device that decelerates the vehicle by applying braking force to the wheels, the method comprising the steps of: executing speed limit control by controlling the drive control device to limit the driving force when the vehicle speed exceeds the speed limit; and executing override control to release the limit on the driving force until the vehicle speed falls below the speed limit when the accelerator opening is increased by the driver while the speed limit control is being executed, Furthermore, a vehicle driving control method that includes the step of controlling the braking control device to decelerate the vehicle when the time during which the accelerator opening is 0 exceeds a reference time while the override control is being performed.

5. A driving control program is applied to a vehicle that includes at least a drive control device that controls the driving force of the vehicle according to the accelerator opening, and a braking control device that decelerates the vehicle by applying braking force to the wheels, and causes an electronic control device mounted on the vehicle to perform the following steps: perform speed limit control by controlling the drive control device to limit the driving force when the vehicle speed exceeds the speed limit; and perform override control to release the limit on the driving force until the vehicle speed falls below the speed limit when the driver increases the accelerator opening while the speed limit control is being performed, Furthermore, a vehicle driving control program that includes a step of controlling the braking control device to decelerate the vehicle when the time during which the accelerator opening is 0 exceeds a reference time while the override control is being performed.

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