Vehicle driving assistance device, vehicle driving assistance method, and vehicle driving assistance program product

Abstract

The present application provides a vehicle driving assistance device capable of suppressing generation of self-excited vibration caused by constant speed travel control. A vehicle driving assistance device (10) executes constant speed travel control that autonomously controls a travel speed of a host vehicle (100) to a set vehicle speed. The vehicle driving assistance device, in execution of the constant speed travel control, in a case where the host vehicle travels on a downward slope having a slope smaller than a prescribed slope threshold value, interrupts the constant speed travel control and executes intermittent braking control that repeatedly implements intermittent braking and a stop of the intermittent braking, the intermittent braking applying a prescribed brake force threshold value or more of brake force to the host vehicle.

Description

Technical Field

[0001] This invention relates to a vehicle driving assistance device, a vehicle driving assistance method, and a vehicle driving assistance program product. Background Technology

[0002] A vehicle driving assistance device is known that, even if the driver of the vehicle does not operate the accelerator pedal or the brake pedal, it can perform constant speed driving control by autonomously controlling the driving force and braking force applied to the vehicle to maintain the vehicle's driving speed at a set speed (for example, see Patent Document 1).

[0003] Prior art literature

[0004] Patent documents

[0005] Patent document 1: Japanese Patent Application Publication No. 2018-31467. Summary of the Invention

[0006] In order to maintain the vehicle's speed at a set speed when the vehicle is traveling downhill, the aforementioned vehicle driving assistance device continuously applies braking force to the vehicle. However, when the downhill slope is gentle, the vehicle driving assistance device continuously applies relatively small braking force to the vehicle for a relatively long period.

[0007] When a small braking force is applied to the vehicle continuously over a long period of time in this manner, vibrations based on thermal expansion (so-called self-excited vibrations) sometimes occur between the brake pads and the brake discs. When such vibrations occur, they can sometimes cause discomfort to the driver of the vehicle.

[0008] The purpose of this invention is to provide a vehicle driving assistance device capable of suppressing the generation of self-excited vibrations caused by constant speed driving control.

[0009] The vehicle driving assistance device of the present invention includes a control device that performs constant speed driving control, autonomously controlling the vehicle's travel speed to a set speed. The control device is configured to, during the execution of the constant speed driving control, when the vehicle is traveling downhill with a gradient less than a predetermined gradient threshold, interrupt the constant speed driving control and perform intermittent braking control, wherein the intermittent braking control repeatedly applies intermittent braking and stops the intermittent braking, and the intermittent braking applies a braking force to the vehicle that is larger than the braking force applied to the vehicle by the constant speed driving control.

[0010] As mentioned above, during the execution of cruise control, when the vehicle is traveling on a slow downhill slope, a small braking force is sometimes applied to the vehicle continuously for a relatively long period of time. In this way, when a small braking force is applied to the vehicle continuously for a long period of time, vibrations based on thermal expansion (so-called self-excited vibrations) sometimes occur between the brake pads and brake discs. When such vibrations occur, they can sometimes cause discomfort to the driver.

[0011] According to the vehicle driving assistance device of the present invention, when the vehicle is traveling downhill with a gradient less than a predetermined gradient threshold during the execution of constant speed driving control, intermittent braking control is performed. In intermittent braking control, the braking force applied to the vehicle is larger than the braking force applied to the vehicle through constant speed driving control. Therefore, the generation of self-excited vibration can be suppressed.

[0012] Furthermore, in the vehicle driving assistance device of the present invention, the control device is configured to, for example, determine that the vehicle is driving on a downhill slope with a gradient less than the gradient threshold if, for a specified time, the braking force applied to the vehicle by the constant speed driving control is less than a specified braking force threshold.

[0013] Therefore, it is possible to determine whether the vehicle is traveling on a gentle downhill slope based on the braking force applied to it.

[0014] Furthermore, in the vehicle driving assistance device of the present invention, the control device is configured to, during the execution of the intermittent braking control, stop the intermittent braking control and restart the constant speed driving control if the vehicle's driving speed becomes a predetermined upper limit speed that is greater than the set vehicle speed or a predetermined lower limit speed that is smaller than the set vehicle speed.

[0015] When the vehicle's speed becomes very high during intermittent braking control, even if intermittent braking control is stopped and cruise control is restarted, a relatively large braking force will be applied to the vehicle, thus reducing the likelihood of self-excited vibration. Therefore, to meet the driver's need to maintain a constant speed, it is preferable to stop intermittent braking control and restart cruise control.

[0016] Furthermore, when the vehicle's speed becomes very low during intermittent braking control, even if intermittent braking control is stopped and cruise control is restarted, there is a high probability that only a very small braking force will be applied to the vehicle, thus reducing the likelihood of self-excited vibration. Therefore, to meet the driver's need to maintain a constant speed, it is preferable to stop intermittent braking control and restart cruise control.

[0017] According to the vehicle driving assistance device of the present invention, when the vehicle's speed becomes very high or very low during the execution of intermittent braking control, the intermittent braking control is stopped and constant speed driving control is resumed. Therefore, the needs of the driver can be met.

[0018] Furthermore, the vehicle of the present invention has the vehicle driving assistance device of the present invention.

[0019] Furthermore, the vehicle driving assistance method of the present invention is a vehicle driving assistance method for performing constant speed driving control, wherein the constant speed driving control autonomously controls the driving speed of the vehicle to a set speed, comprising: during the execution of the constant speed driving control, when the vehicle is driving downhill with a gradient less than a predetermined gradient threshold, interrupting the constant speed driving control and performing intermittent braking control, wherein the intermittent braking control repeatedly performs intermittent braking and stops the intermittent braking, wherein the intermittent braking applies a braking force to the vehicle that is larger than the braking force applied to the vehicle by the constant speed driving control.

[0020] Furthermore, the vehicle driving assistance program product of the present invention includes a vehicle driving assistance program that performs cruise control, wherein the cruise control autonomously controls the vehicle's speed to a set speed, and the vehicle driving assistance program is configured to, during the execution of the cruise control, interrupt the cruise control and perform intermittent braking control when the vehicle is traveling downhill with a gradient less than a specified gradient threshold, wherein the intermittent braking control repeatedly performs intermittent braking and stops the intermittent braking, and the intermittent braking applies a larger braking force to the vehicle than the braking force applied to the vehicle by the cruise control.

[0021] The constituent elements of this invention are not limited to the embodiments described below with reference to the accompanying drawings. Other objects, features, and incidental advantages of this invention can be readily understood from the description of embodiments thereof. Attached Figure Description

[0022] Figure 1 This is a diagram illustrating a vehicle driving assistance device according to an embodiment of the present invention and a vehicle (this vehicle) using the vehicle driving assistance device.

[0023] Figure 2 Diagram (A) shows a scenario where the vehicle follows the vehicle in front using follow-traffic control. Figure 2 The middle (B) graph represents the case where the distance between the workshops is longer compared to the distance to the target workshop. Figure 2 The diagram in the middle (C) represents the case where the distance between the workshops is shorter compared to the distance between the target workshops.

[0024] Figure 3This diagram represents a situation where there is no vehicle moving forward.

[0025] Figure 4 This is a timing diagram representing the processing based on intermittent braking control as the vehicle speed increases.

[0026] Figure 5 This is a timing diagram representing the processing based on intermittent braking control when the vehicle speed decreases.

[0027] Figure 6 This is a timing diagram illustrating an example of the processing when intermittent braking control is executed.

[0028] Figure 7 This is a flowchart illustrating the procedures executed by the vehicle driving assistance device according to an embodiment of the present invention.

[0029] Figure 8 This is a flowchart illustrating the procedures executed by the vehicle driving assistance device according to an embodiment of the present invention.

[0030] Figure 9 This is a flowchart illustrating the procedures executed by the vehicle driving assistance device according to an embodiment of the present invention.

[0031] Figure 10 This is a flowchart illustrating the procedures executed by the vehicle driving assistance device according to an embodiment of the present invention. Detailed Implementation

[0032] Hereinafter, with reference to the accompanying drawings, an embodiment of the vehicle driving assistance device 10 of the present invention will be described. Figure 1 As shown, the vehicle 100 is equipped with a vehicle driving assistance device 10.

[0033] The vehicle driving assistance device 10 includes an ECU 90 as a control unit. The ECU 90 has a microcomputer as its main component. The ECU 90 includes a CPU, ROM, RAM, non-volatile memory, and interfaces. The CPU performs various functions by executing instructions (programs, procedures) stored in the ROM.

[0034] <Vehicle Running Gear>

[0035] Furthermore, a vehicle running gear 20 is mounted on the vehicle 100. The vehicle running gear 20 is a device for driving, braking and steering the vehicle 100, and in this example, it includes a drive device 21, a braking device 22 and a steering device 23.

[0036] <Drive device>

[0037] The drive unit 21 is a device that outputs driving force to the vehicle 100 to make the vehicle 100 move. In this example, it is an internal combustion engine, but it can also be an electric motor, or a combination of an internal combustion engine and an electric motor. The drive unit 21 is electrically connected to the ECU 90. The ECU 90 can control the driving force output from the drive unit 21 by controlling the operation of the drive unit 21.

[0038] Braking device

[0039] Braking device 22 is a device that outputs braking force to the vehicle 100 for braking the vehicle 100. In this example, it is a hydraulic braking device that applies braking force to the vehicle 100 by hydraulically pressing the brake pads onto the brake discs of each wheel of the vehicle 100. Braking device 22 is electrically connected to ECU 90. ECU 90 can control the braking force output from braking device 22 by controlling its operation.

[0040] Steering mechanism

[0041] The steering device 23 is a device that outputs a steering force applied to the vehicle 100 to steer the vehicle 100, such as a power steering device. The steering device 23 is electrically connected to the ECU 90. The ECU 90 can control the steering force output from the steering device 23 by controlling the operation of the steering device 23.

[0042] <Sensors, etc.>

[0043] Furthermore, the vehicle 100 is equipped with an accelerator pedal 41, an accelerator pedal operation sensor 42, a brake pedal 43, a brake pedal operation sensor 44, a steering wheel 45, a steering shaft 46, a steering angle sensor 47, a steering torque sensor 48, a following driving control 49, a vehicle speed detection device 50, and a surrounding information detection device 60.

[0044] Accelerator pedal operation sensor

[0045] Accelerator pedal operation amount sensor 42 is a sensor that detects the operation amount of accelerator pedal 41. Accelerator pedal operation amount sensor 42 is electrically connected to ECU 90. Accelerator pedal operation amount sensor 42 sends the detected operation amount information of accelerator pedal 41 to ECU 90. Based on this information, ECU 90 obtains the operation amount of accelerator pedal 41 as accelerator pedal operation amount AP.

[0046] The ECU 90 calculates the requested driving force (requested driving torque) based on the accelerator pedal operation amount AP and the vehicle speed (vehicle speed), and performs normal acceleration / deceleration control to control the operation of the drive unit 21, thereby outputting the requested driving force. Furthermore, when performing follow-drive control, cruise control, or intermittent braking control (described later), the ECU 90 determines the driving force required to move the vehicle 100, thereby achieving the target acceleration GA_TGT or target deceleration GD_TGT set by the follow-drive control, cruise control, or intermittent braking control, and controls the operation of the drive unit 21 to output the driving force.

[0047] Brake pedal operation sensor

[0048] Brake pedal operation amount sensor 44 is a sensor that detects the operation amount of brake pedal 43. Brake pedal operation amount sensor 44 is electrically connected to ECU 90. Brake pedal operation amount sensor 44 sends the detected operation amount information of brake pedal 43 to ECU 90. Based on this information, ECU 90 obtains the operation amount of brake pedal 43 as brake pedal operation amount BP.

[0049] The ECU 90 calculates the requested braking force (requested braking torque) from the brake pedal operation amount BP and executes normal acceleration / deceleration control to control the operation of the braking device 22, thereby outputting the requested braking force. Furthermore, when executing follow-drive control, cruise control, or intermittent braking control (described later), the ECU 90 determines the braking force required to brake the vehicle 100 to achieve the target acceleration GA_TGT or target deceleration GD_TGT set by the follow-drive control, cruise control, or intermittent braking control, and controls the operation of the braking device 22 to output the braking force.

[0050] <Steering Angle Sensor>

[0051] Steering angle sensor 47 is a sensor that detects the rotation angle of steering shaft 46 relative to the neutral position and is electrically connected to ECU 90. Steering angle sensor 47 sends the detected rotation angle information of steering shaft 46 to ECU 90. ECU 90 obtains the rotation angle of steering shaft 46 as the steering angle θ based on this information.

[0052] <Steering torque sensor>

[0053] The steering torque sensor 48 is a sensor that detects the torque input from the driver's DV to the steering shaft 46 via the steering wheel 45 in the vehicle 100, and is electrically connected to the ECU 90. The steering torque sensor 48 sends the detected torque information to the ECU 90. Based on this information, the ECU 90 obtains the torque input from the driver's DV to the steering shaft 46 via the steering wheel 45 (driver input torque).

[0054] The ECU 90 obtains the requested steering force (requested steering torque) based on the steering angle θ, the driver input torque, and the vehicle speed (vehicle speed) of the vehicle 100, and controls the operation of the steering device 23 to output the requested steering torque from the steering device 23.

[0055] <Follow-up driving control>

[0056] The following control 49 is a device operated by the driver's DV of the vehicle 100. The following control 49 is a device consisting of switches, buttons, etc. These switches, buttons, etc. are provided, for example, on the steering wheel of the vehicle 100, or on a rod mounted on the steering column of the vehicle 100.

[0057] In this example, the following control 49 includes a following selection switch, a speed setting switch, a speed increase button, a speed decrease button, and a vehicle distance setting button. The following control 49 is electrically connected to the ECU 90.

[0058] When driver assistance controls, including follow-drive control, cruise control, and intermittent braking control (described later), are not being executed, a specific signal is sent from the follow-drive selector switch 49 to the ECU 90 when the follow-drive selector switch is operated by the driver (DV). Upon receiving this signal, the ECU 90 determines that the driver (DV) has requested the execution of driver assistance controls. Furthermore, when the ECU 90 determines that the driver (DV) has requested the execution of driver assistance controls, it executes follow-drive control when a vehicle is in front and executes cruise control when no vehicle is in front.

[0059] On the other hand, when driver assistance control is executed, a specific signal is sent from the follow-drive selector switch 49 to the ECU 90 when the follow-drive selector switch is operated by the driver (DV). Upon receiving this signal, the ECU 90 determines that the driver (DV) has requested the termination of driver assistance control. Then, the ECU 90 terminates the follow-drive control, cruise control, or intermittent braking control upon determining that the driver (DV) has requested the termination of driver assistance control. Furthermore, as described later, when intermittent braking control is executed, cruise control is interrupted, but when the ECU 90 terminates intermittent braking control, cruise control also terminates.

[0060] Furthermore, when performing driver assistance control, if the vehicle speed setting switch is operated by the driver (DV), a specific signal is sent from the following driving controller 49 to the ECU 90. Upon receiving this signal, the ECU 90 sets the vehicle speed (vehicle speed) of the vehicle 100 at that moment to the set speed V_SET in the cruise control.

[0061] Furthermore, when performing driver assistance control, if the driver operates the speed increase button via DV, a specific signal is sent from the follow-drive controller 49 to the ECU 90. Upon receiving this signal, the ECU 90 increases the set speed V_SET. Conversely, when performing driver assistance control, if the driver operates the speed decrease button via DV, a specific signal is sent from the follow-drive controller 49 to the ECU 90. Upon receiving this signal, the ECU 90 decreases the set speed V_SET.

[0062] Furthermore, when performing driver assistance control, a specific signal is sent from the follow-drive controller 49 to the ECU 90 when the driver operates the distance setting button via the DV. This specific signal is a signal indicating the distance D requested as the target distance D_TGT (specified distance) by the driver operating the distance setting button via the DV (request distance signal).

[0063] like Figure 2 As shown in (A), the inter-vehicle distance D is the distance between the preceding vehicle 200 and the current vehicle 100, and the target inter-vehicle distance D_TGT is the target inter-vehicle distance D in the following driving control. In this example, the preceding vehicle 200 is the vehicle traveling in the lane (vehicle lane LN1) of the current vehicle 100 within a specified distance ahead of the current vehicle 100. Furthermore, in the figure, the symbol LN2 is the lane adjacent to the current vehicle lane LN1, which in this example is the lane for oncoming vehicles.

[0064] In this example, by using the driver's DV operation to set the inter-vehicle distance, the inter-vehicle distance D that can be requested as the target inter-vehicle distance D_TGT is one of three types: long distance, medium distance, and short distance.

[0065] Upon receiving a requested inter-vehicle distance signal, the ECU 90 sets the target inter-vehicle distance D_TGT based on the inter-vehicle distance D (requested inter-vehicle distance D_REQ) represented by the signal.

[0066] ECU 90 can set the target inter-vehicle distance D_TGT corresponding to the requested inter-vehicle distance D_REQ without considering the current vehicle speed V100, but in this example, the current vehicle speed V100 is taken into account when setting the target inter-vehicle distance D_TGT corresponding to the requested inter-vehicle distance D_REQ.

[0067] Specifically, ECU 90 sets the time (arrival prediction time TTC) obtained by dividing the current vehicle speed V100 by the time obtained ...

[0068] TTC_REF=D / V100…(1)

[0069] The arrival prediction time TTC_REF is specified as a longer time TTClong when the distance between the requesting workshop and D_REQ is long, a medium time TTCmid when the distance between the requesting workshop and D_REQ is medium, and a shorter time TTCshort when the distance between the requesting workshop and D_REQ is short.

[0070] <Vehicle speed detection device>

[0071] The vehicle speed detection device 50 is a device for detecting the driving speed of the vehicle 100, such as a wheel speed sensor. The vehicle speed detection device 50 is electrically connected to the ECU 90. The vehicle speed detection device 50 sends the detected driving speed information of the vehicle 100 to the ECU 90. Based on this information, the ECU 90 obtains the driving speed of the vehicle 100 as the vehicle speed V100.

[0072] <Surrounding Information Detection Device>

[0073] The surrounding information detection device 60 has an electromagnetic wave sensor 61 and an image sensor 62.

[0074] <Electronic Wave Sensor>

[0075] The radio wave sensor 61 is a sensor that uses radio waves to detect information related to objects present in the vicinity of the vehicle 100. It is, for example, at least one of an acoustic sensor such as a radar sensor (millimeter-wave radar), an ultrasonic sensor (gap sonar), and an optical sensor such as a lidar (LiDAR). The radio wave sensor 61 is electrically connected to the ECU 90. The radio wave sensor 61 transmits radio waves and receives radio waves reflected by objects (reflected waves). The radio wave sensor 61 sends information related to the transmitted and received radio waves (reflected waves) to the ECU 90. In other words, the radio wave sensor 61 detects objects present in the vicinity of the vehicle 100 and sends information related to the detected objects to the ECU 90. The ECU 90 can obtain information (peripheral information IS) related to objects present in the vicinity of the vehicle 100 based on this information (radio wave information IR or radio wave data). Objects detected by the radio wave sensor 61 include, for example, vehicles, walls, bicycles, and people.

[0076] Image Sensor

[0077] Image sensor 62 is a sensor, such as a camera, that captures images of the surroundings of vehicle 100. Image sensor 62 is electrically connected to ECU 90. Image sensor 62 captures images of the surroundings of vehicle 100 and sends information related to the captured images to ECU 90. ECU 90 can obtain surrounding information (surroundings information IS) of vehicle 100 based on this information (image information IC or image data).

[0078] <Summary of the operation of vehicle driver assistance devices>

[0079] Next, the operation of the vehicle driving assistance device 10 will be explained. When the vehicle driving assistance device 10 determines that the driver DV has requested the execution of follow control, it executes the following follow control or constant speed control.

[0080] <Follow-up driving control>

[0081] like Figure 2 As shown in (A), the vehicle driving assistance device 10 performs follow-traffic control when a vehicle ahead 200 is present. Follow-traffic control is a control that maintains a predetermined distance between the vehicle 100 and the vehicle ahead 200 by autonomously controlling the operation of the drive unit 21 and / or the braking unit 22, even without driver DV operation on the accelerator pedal 41 or the brake pedal 43. Furthermore, the vehicle driving assistance device 10 can determine the presence of the vehicle ahead 200 based on surrounding information IS.

[0082] When the vehicle driving assistance device 10 starts following driving control, it obtains the deviation (distance deviation dD) between the vehicle distance D and the target distance D_TGT, and performs feedback control such as PID control on the operation of the drive device 21 and / or the braking device 22 to keep the distance deviation dD close to zero, thereby keeping the distance D at the target distance D_TGT.

[0083] Specifically, such as Figure 2 As shown in (B), when the inter-vehicle distance D is longer than the target inter-vehicle distance D_TGT, the vehicle driving assistance device 10 calculates the target acceleration GA_TGT by making the inter-vehicle distance D shorter, and controls the action of the drive device 21 to achieve the target acceleration GA_TGT. As a result, the vehicle speed V100 increases, and the inter-vehicle distance D becomes shorter, approaching the target inter-vehicle distance D_TGT.

[0084] On the other hand, such as Figure 2 As shown in (C), when the inter-vehicle distance D is shorter than the target inter-vehicle distance D_TGT, the vehicle driving assistance device 10 calculates the target deceleration GD_TGT as the inter-vehicle distance D increases, and controls the operation of the braking device 22 (and / or the drive device 21) to achieve the target deceleration GD_TGT. As a result, the vehicle speed V100 decreases, and consequently, the inter-vehicle distance D increases, approaching the target inter-vehicle distance D_TGT.

[0085] In this example, when the target vehicle distance D_TGT is below zero, the vehicle 100 contacts the preceding vehicle 200. Therefore, the target vehicle distance D_TGT is a value greater than zero, and is set to a sufficient value to prevent the vehicle 100 from contacting the preceding vehicle 200 even if the preceding vehicle 200 decelerates rapidly.

[0086] <Cruise Control>

[0087] like Figure 3 As shown, in the absence of a preceding vehicle 200, the vehicle driving assistance device 10 performs cruise control. Cruise control is a control that maintains the vehicle speed V100 at a set vehicle speed V_SET by autonomously controlling the operation of the drive unit 21 and / or the braking unit 22, even without any operation of the accelerator pedal 41 or the brake pedal 43 based on the driver's DV.

[0088] When the vehicle driving assistance device 10 starts constant speed driving control, it obtains the deviation (vehicle speed deviation dV) between the vehicle speed V100 and the set vehicle speed V_SET, and performs feedback control such as PID control on the operation of the drive device 21 and / or the braking device 22 to make the vehicle speed deviation dV close to zero, thereby maintaining the vehicle speed V100 at the set vehicle speed V_SET.

[0089] Specifically, when the vehicle speed V100 is greater than the set vehicle speed V_SET, the vehicle driving assistance device 10 calculates the target deceleration GD_TGT by reducing the vehicle speed V100, and controls the operation of the braking device 22 and / or the drive device 21 to achieve the target deceleration GD_TGT. As a result, the vehicle speed V100 decreases and approaches the set vehicle speed V_SET.

[0090] On the other hand, when the vehicle speed V100 is less than the set vehicle speed V_SET, the vehicle driving assistance device 10 calculates the target acceleration GA_TGT as the vehicle speed V100 increases, and controls the operation of the drive device 21 to achieve the target acceleration GA_TGT. As a result, the vehicle speed V100 increases and approaches the set vehicle speed V_SET.

[0091] However, during the execution of cruise control, when the vehicle 100 is traveling downhill, the vehicle driving assistance device 10 continuously applies braking force to the vehicle 100 in order to maintain the vehicle speed V100 at the set speed V_SET. At this time, when the downhill slope on which the vehicle 100 is traveling is gentle (i.e., when the vehicle 100 is traveling on a gentle downhill slope), the vehicle driving assistance device 10 continuously applies a relatively small braking force to the vehicle 100 for a relatively long period of time.

[0092] Thus, when a small braking force is continuously applied to the vehicle 100 for a long period of time, vibrations based on thermal expansion (so-called self-excited vibrations) sometimes occur between the brake pads and the brake disc. When such vibrations occur, they can sometimes cause discomfort to the driver of the vehicle 100.

[0093] Therefore, when the vehicle 100 is traveling downhill with a gradient less than a specified gradient threshold during the execution of cruise control, the vehicle driving assistance device 10 interrupts cruise control and initiates intermittent braking control. That is, when the condition (intermittent braking control initiation condition) is met (the vehicle 10 interrupts cruise control and initiates intermittent braking control) during the execution of cruise control.

[0094] More specifically, in this example, when the vehicle driving assistance device 10 applies braking force to the vehicle 100 during the execution of cruise control, if the braking force is less than a predetermined value (predetermined braking force threshold BK_TH) for a predetermined time (predetermined time T_TH), it is determined that the vehicle 100 is traveling downhill with a gradient less than a predetermined gradient threshold during the execution of cruise control, and the cruise control is interrupted to execute intermittent braking control. That is, when the condition that the braking force is less than the predetermined braking force threshold BK_TH for a predetermined time T_TH during the execution of cruise control is met, the intermittent braking control start condition is met, the cruise control is interrupted, and intermittent braking control begins.

[0095] In this example, the braking force threshold BK_TH is set as the lower limit of the braking force that does not produce self-excited vibration in the braking device 22.

[0096] Intermittent braking control

[0097] like Figure 4 As shown, when the braking force of the vehicle driving assistance device 10 is less than the specified braking force threshold BK_TH during the execution of the constant speed driving control and the intermittent braking control is started (at time t40), the braking force applied to the vehicle 100 (the braking force applied by the vehicle) is temporarily reduced to zero.

[0098] Then, as Figure 4 As shown, when the vehicle speed V100 increases and reaches the fuel cut-off start speed threshold V_P1 during the execution of intermittent braking control (time t41), the vehicle driving assistance device 10 initiates fuel cut-off. That is, the fuel cut-off start condition is met when the vehicle speed V100 increases and reaches the fuel cut-off start speed threshold V_P1 during the execution of intermittent braking control. The fuel cut-off start speed threshold V_P1 is set to a value that is greater than a predetermined value (the first increment dV_P1) compared to the set vehicle speed V_SET.

[0099] Furthermore, fuel cutoff is a process that stops fuel injection from the fuel injection valve of the internal combustion engine, which serves as the drive unit 21. Therefore, when fuel cutoff is implemented, so-called engine braking is applied to the vehicle 100, causing it to decelerate. Additionally, when the accelerator pedal operation amount AP is zero, the vehicle operation support device 10 injects an amount of fuel from the fuel injection valve sufficient to allow the internal combustion engine to operate autonomously, thus running the internal combustion engine. In this case, engine braking is also applied to the vehicle 100, but the deceleration of the vehicle 100 is smaller compared to the deceleration when fuel cutoff is implemented. Furthermore, the vehicle driving assistance device 10 is configured to also inject an amount of fuel from the fuel injection valve sufficient to allow the internal combustion engine to operate autonomously when braking force is applied to the vehicle 100, thus running the internal combustion engine.

[0100] In addition, such as Figure 4 As shown, when the vehicle speed V100 increases and reaches the intermittent braking start speed threshold V_P2 during the execution of intermittent braking control (at time t42), the vehicle driving assistance device 10 begins to apply intermittent braking with a predetermined amount of braking force (predetermined intermittent braking force BK_SET) to the vehicle 100. That is, when the intermittent braking start condition of the vehicle speed V100 increasing to reach the intermittent braking start speed threshold V_P2 during the execution of intermittent braking control is met, the vehicle driving assistance device 10 begins intermittent braking. The predetermined intermittent braking force BK_SET is set to a braking force greater than or equal to the predetermined braking force threshold BK_TH. Furthermore, the intermittent braking start speed threshold V_P2 is set to a value that is greater than the set speed V_SET by a predetermined value (second increment dV_P2). The second increment dV_P2 is set to a value greater than the first increment dV_P1. At this time, the vehicle driving assistance device 10 continues to cut off the fuel supply.

[0101] In addition, such as Figure 4 As shown, when the vehicle speed V100 increases during the execution of intermittent braking control and reaches the acceleration-side control stop speed threshold V_P3 (a predetermined upper limit speed) (at time t43), the vehicle driving assistance device 10 stops the intermittent braking control and resumes constant speed driving control. That is, when the control stop condition of the vehicle speed V100 increasing to reach the acceleration-side control stop speed threshold V_P3 during the execution of intermittent braking control is met, the vehicle driving assistance device 10 stops the intermittent braking control and resumes constant speed driving control. The acceleration-side control stop speed threshold V_P3 is set to be a value that is greater than a predetermined value (the third increment dV_P3) compared to the set speed V_SET. The third increment dV_P3 is set to be a value greater than the second increment dV_P2. Furthermore, at this time, since the intermittent braking control stops, both fuel cut-off and intermittent braking stop.

[0102] On the other hand, such as Figure 5 As shown, when the vehicle speed V100 decreases to the intermittent braking stop speed threshold V_N1 during the execution of intermittent braking control (time t50), the vehicle driving assistance device 10 stops intermittent braking. That is, when the intermittent braking stop condition of the vehicle speed V100 decreasing to the intermittent braking stop speed threshold V_N1 during the execution of intermittent braking control is met, the vehicle driving assistance device 10 stops intermittent braking. The intermittent braking stop speed threshold V_N1 is set to a value that is less than a predetermined value (a first reduction amplitude dV_N1) compared to the set vehicle speed V_SET. Furthermore, at this time, the vehicle driving assistance device 10 does not stop fuel cutoff.

[0103] In addition, such as Figure 5 As shown, when the vehicle speed V100 decreases during intermittent braking control and reaches the fuel cut-off stop speed threshold V_N2 (time t51), the vehicle driving assistance device 10 stops fuel cut-off. The fuel cut-off stop speed threshold V_N2 is set to a value that is smaller than the set speed V_SET by a predetermined value (second reduction amplitude dV_N2). The second reduction amplitude dV_N2 is set to a value that is larger than the first reduction amplitude dV_N1.

[0104] In addition, such as Figure 5 As shown, when the vehicle speed V100 decreases during the execution of intermittent braking control and reaches the deceleration-side control stop speed threshold V_N3 (a specified lower limit speed) (at time t52), the vehicle driving assistance device 10 stops the intermittent braking control and restarts the constant speed driving control. That is, when the control stop condition of the vehicle speed V100 decreasing to reach the deceleration-side control stop speed threshold V_N3 during the execution of intermittent braking control is met, the vehicle driving assistance device 10 stops the intermittent braking control and restarts the constant speed driving control. The deceleration-side control stop speed threshold V_N3 is set to be a value that is smaller than the set speed V_SET by a specified value (the third deceleration amplitude dV_N3). The third deceleration amplitude dV_N3 is set to be a value larger than the second deceleration amplitude dV_N2.

[0105] As explained above, when the vehicle driving assistance device 10 is configured to perform intermittent braking control, when the vehicle 100 is traveling on a gentle downhill slope, the braking force applied to the vehicle 100 (vehicle applied braking force) is, for example... Figure 6 It is controlled as shown.

[0106] If, during the execution of cruise control, the vehicle applies a braking force less than the specified braking force threshold BK_TH for a specified time T_TH (time t60), cruise control is interrupted and intermittent braking control begins. When intermittent braking control begins, the applied braking force is reduced to zero. Therefore, the vehicle speed V100 begins to increase.

[0107] Then, when the vehicle speed V100 rises to the fuel cutoff start speed threshold V_P1 (time t61), fuel cutoff begins. Furthermore, when the vehicle speed V100 rises to the intermittent braking start speed threshold V_P2 (time t62), intermittent braking begins. That is, a specified intermittent braking force BK_SET, greater than the specified braking force threshold BK_TH, is applied to the vehicle 100. Thus, in Figure 6 In the example shown, the vehicle speed V100 begins to decrease.

[0108] When the vehicle speed V100 decreases and reaches the intermittent braking stopping speed threshold V_N1 (time t63), intermittent braking stops. Therefore, in Figure 6 In the example shown, the vehicle speed V100 begins to increase. Subsequently, when the vehicle speed V100 reaches the intermittent braking initiation speed threshold V_P2 (time t64), intermittent braking begins. Thus, in... Figure 6 In the example shown, the vehicle speed V100 begins to decrease. Then, when the vehicle speed V100 decreases and reaches the intermittent braking stopping speed threshold V_N1 (time t65), intermittent braking stops. Thus, in Figure 6 In the example shown, the vehicle speed V100 begins to increase. Subsequently, when the vehicle speed V100 increases and reaches the intermittent braking initiation speed threshold V_P2 (time t66), intermittent braking begins. Thus, in... Figure 6 In the example shown, the vehicle speed V100 begins to decrease. Then, when the vehicle speed V100 decreases and reaches the intermittent braking stopping speed threshold V_N1 (time t67), intermittent braking stops.

[0109] <Effect>

[0110] As mentioned earlier, during the execution of cruise control, when the vehicle 100 is traveling downhill at a slow speed, a relatively small braking force is sometimes continuously applied to the vehicle 100 for a relatively long period of time. This continuous application of a small braking force to the vehicle 100 for an extended period can sometimes generate vibrations (so-called self-excited vibrations) between the brake pads and brake discs due to thermal expansion. When such vibrations occur, they can sometimes cause discomfort to the driver of the vehicle 100.

[0111] According to the vehicle driving assistance device 10, when the braking force is less than the specified braking force threshold BK_TH during the execution of constant speed driving control for a specified time T_TH, intermittent braking control is performed. In intermittent braking control, the braking force applied to the vehicle 100 is greater than the specified braking force threshold BK_TH. Therefore, the generation of self-excited vibration can be suppressed.

[0112] Furthermore, according to the vehicle driving assistance device 10, as referenced Figure 6As illustrated in the example, during the execution of intermittent braking control, the application and stopping of braking force to the vehicle 100 are alternately and repeatedly performed. Therefore, during the execution of intermittent braking control, the vehicle speed V100 can be maintained near the set vehicle speed V_SET.

[0113] <Specific Operations of Vehicle Driving Assistance Devices>

[0114] Next, the specific operation of the vehicle driving assistance device 10 will be explained. The CPU of the ECU 90 of the vehicle driving assistance device 10 executes calculations according to a predetermined cycle. Figure 7 The procedure is shown. Therefore, when the specified timing is reached, the CPU... Figure 7 The procedure shown begins at step 700 and proceeds to step 705, where it is determined whether to request the execution of driver assistance control.

[0115] If the CPU determines "yes" in step 705, the process proceeds to step 710 to determine whether there is a preceding vehicle 200.

[0116] If the CPU determines "yes" in step 710, the process proceeds to step 715 and execution begins. Figure 8 The procedure is shown. Therefore, when processing enters step 715, the CPU... Figure 8 The procedure shown in step 800 begins processing, which leads to step 805, where it is determined whether the workshop distance D is longer than the target workshop distance D_TGT.

[0117] If the CPU determines "yes" in step 805, the process proceeds to step 810, whereby it calculates the acceleration required to make the inter-vehicle distance D equal to the target inter-vehicle distance D_TGT as the target acceleration GA_TGT, calculates the driving force that should be applied to the vehicle 100 to achieve the target acceleration GA_TGT as the target driving force DR_TGT, and controls the operation of the drive unit 21 by applying the target driving force DR_TGT from the drive unit 21 to the vehicle 100. Next, the CPU proceeds via step 895... Figure 7 Step 795 of the procedure shown temporarily concludes this procedure.

[0118] On the other hand, if the CPU determines "no" in step 805, the process proceeds to step 815 to determine whether the workshop distance D is shorter than the target workshop distance D_TGT.

[0119] If the CPU determines "yes" in step 815, the process proceeds to step 820. It calculates the deceleration required to make the inter-vehicle distance D equal to the target inter-vehicle distance D_TGT as the target deceleration GD_TGT, and calculates the braking force that should be applied to the vehicle 100 to achieve this target deceleration GD_TGT as the target braking force BK_TGT. The CPU then controls the operation of the braking device 22 and / or the drive device 21 by applying this target braking force BK_TGT to the vehicle 100. Next, the CPU proceeds via step 895... Figure 7 Step 795 of the procedure shown temporarily concludes this procedure.

[0120] On the other hand, if the CPU determines "no" in step 815, the process proceeds to step 825, whereby it calculates the driving force required to maintain the current vehicle speed V100 as the target driving force DR_TGT, and controls the operation of the drive unit 21 by applying this target driving force DR_TGT from the drive unit 21 to the vehicle 100. Next, the CPU proceeds via step 895... Figure 7 Step 795 of the procedure shown temporarily concludes this procedure.

[0121] In addition, the CPU Figure 7 If step 710 of the procedure is determined to be "no", the process proceeds to step 720 to determine whether intermittent braking control is being executed.

[0122] If the CPU determines "yes" in step 720, it proceeds to step 725 to determine whether the intermittent braking stop condition is met.

[0123] If the CPU determines "yes" in step 725, the process proceeds to step 730 and executes. Figure 9 The procedure is shown. Therefore, when the CPU processes and enters step 730, from... Figure 9 The procedure shown begins processing from step 900, leading to step 905, where it is determined whether the vehicle speed V100 is lower than the set vehicle speed V_SET.

[0124] If the CPU determines "yes" in step 905, the process proceeds to step 910, whereby it calculates the acceleration required to make the vehicle speed V100 match the set vehicle speed V_SET as the target acceleration GA_TGT, and calculates the driving force that should be applied to the vehicle 100 to achieve the target acceleration GA_TGT as the target driving force DR_TGT. The CPU then controls the operation of the drive unit 21 by applying the target driving force DR_TGT from the drive unit 21 to the vehicle 100. Next, the CPU proceeds via step 995... Figure 7 Step 795 of the procedure shown temporarily concludes this procedure.

[0125] On the other hand, if the CPU determines "no" in step 905, the process proceeds to step 915 to determine whether the vehicle speed V100 is higher than the set vehicle speed V_SET.

[0126] If the CPU determines "yes" in step 915, the process proceeds to step 920, whereby it calculates the deceleration required to make the vehicle speed V100 match the set vehicle speed V_SET as the target deceleration GD_TGT, and calculates the braking force that should be applied to the vehicle 100 to achieve the target deceleration GD_TGT as the target braking force BK_TGT. The CPU then controls the operation of the braking device 22 and / or the drive device 21 by applying the target braking force BK_TGT to the vehicle 100. Next, the CPU proceeds via step 995... Figure 7 Step 795 of the procedure shown temporarily concludes this procedure.

[0127] On the other hand, if the CPU determines "no" in step 915, the process proceeds to step 925, whereby it calculates the driving force required to maintain the current vehicle speed V100 as the target driving force DR_TGT, and controls the operation of the drive unit 21 by applying this target driving force DR_TGT from the drive unit 21 to the vehicle 100. Next, the CPU proceeds via step 995... Figure 7 Step 795 of the procedure shown temporarily concludes this procedure.

[0128] In addition, the CPU Figure 7 If step 725 of the procedure shown is "no", the process proceeds to step 740 and is executed. Figure 10 The procedure is shown. Therefore, when the CPU processes the process entering step 740, it starts from... Figure 10 The procedure shown begins processing from step 1000, which leads to step 1005, where it is determined whether the vehicle speed V100 has increased.

[0129] If the CPU determines "yes" in step 1005, the process proceeds to step 1010 to determine whether the vehicle speed V100 is above the fuel cut-off start speed threshold V_P1.

[0130] If the CPU determines "yes" in step 1010, the process proceeds to step 1015 to implement fuel cutoff. Then, the CPU proceeds to step 1020 to determine whether the vehicle speed V100 is above the intermittent braking start speed threshold V_P2.

[0131] If the CPU determines "yes" in step 1020, the process proceeds to step 1025 to implement intermittent braking. That is, a predetermined intermittent braking force BK_SET is applied to the vehicle 100. Then, the CPU proceeds via step 1095... Figure 7 Step 795 of the procedure shown temporarily concludes this procedure.

[0132] On the other hand, if the CPU determines "no" in step 1010 or step 1020, it directly proceeds via step 1095. Figure 7 Step 795 of the procedure shown temporarily concludes this procedure.

[0133] Furthermore, if the CPU determines "no" in step 1005, the process proceeds to step 1030 to determine whether the vehicle speed V100 has decreased.

[0134] If the CPU determines "yes" in step 1030, it proceeds to step 1035 to determine whether the vehicle speed V100 is below the intermittent braking stop speed threshold V_N1.

[0135] If the CPU determines "yes" in step 1030, the process proceeds to step 1040 to stop intermittent braking. Next, the CPU proceeds to step 1045 to determine whether the vehicle speed V100 is below the fuel cutoff stop speed threshold V_N2.

[0136] If the CPU determines "yes" in step 1045, the process proceeds to step 1050, stopping the fuel cutoff. Then, the CPU proceeds via step 1095... Figure 7 Step 795 of the procedure shown temporarily concludes this procedure.

[0137] On the other hand, if the CPU determines "no" in step 1035 or step 1045, it directly proceeds via step 1095. Figure 7 Step 795 of the procedure shown temporarily concludes this procedure.

[0138] In addition, the CPU Figure 7 If the determination in step 720 of the procedure shown is "no", the process proceeds to step 735 to determine whether the intermittent braking control start condition is met.

[0139] If the CPU determines "yes" in step 735, the process proceeds to step 740, as described above, and executes... Figure 10 The procedure is shown, and then the process proceeds to step 795, temporarily ending this procedure.

[0140] On the other hand, if the CPU determines "no" in step 735, it proceeds to step 745, and executes as described above. Figure 9The procedure is shown, and then the process proceeds to step 795, temporarily ending this procedure.

[0141] Furthermore, if the CPU determines "no" in step 705, the process proceeds to step 750 to perform normal acceleration / deceleration control.

[0142] The above describes the specific actions of the vehicle driving assistance device 10.

[0143] Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention.

[0144] Explanation of reference numerals in the attached figures

[0145] 10. Vehicle driving assistance devices;

[0146] 20. Vehicle running gear;

[0147] 21. Drive unit;

[0148] 22. Braking device;

[0149] 49. Follow-up driving control;

[0150] 50 km / h vehicle speed detection device;

[0151] 60 Surrounding information detection devices;

[0152] 61. Radio wave sensor;

[0153] 62 Image sensor;

[0154] 90ECU;

[0155] 100 vehicles;

[0156] 200 Forward Vehicle.

Claims

1. A vehicle driving assistance device, comprising a control device that autonomously controls the vehicle's speed to a set speed, wherein the control device performs constant speed driving control. The control device is configured to, during the execution of the constant speed driving control, when the vehicle is traveling downhill with a gradient less than a predetermined gradient threshold (i.e., the downhill is slower than a downhill with the predetermined gradient threshold), continuously apply braking force generated by the brake pads pressing against the brake discs of the vehicle for a prolonged period of time to the vehicle, interrupt the constant speed driving control and execute intermittent braking control. The intermittent braking control repeatedly applies intermittent braking and stops the intermittent braking, and the intermittent braking applies a larger braking force to the vehicle than the braking force applied to the vehicle by the constant speed driving control.

2. The vehicle driving assistance device according to claim 1, wherein, The control device is configured to determine that the vehicle is traveling on a downhill slope with a gradient less than the gradient threshold if the braking force applied to the vehicle by the constant speed driving control is less than a predetermined braking force threshold for a predetermined time.

3. The vehicle driving assistance device according to claim 1 or 2, wherein, The control device is configured to, during the execution of the intermittent braking control, if the vehicle's speed becomes either above a predetermined upper limit speed which is greater than the set speed or below a predetermined lower limit speed which is less than the set speed, stop the intermittent braking control and restart the constant speed driving control.

4. A type of vehicle, The vehicle driving assistance device has any one of claims 1 to 3.

5. A vehicle driving assistance method, which is a vehicle driving assistance method for performing cruise control, wherein the cruise control autonomously controls the vehicle's speed to a set speed, the vehicle driving assistance method comprising: When the vehicle is traveling downhill with a gradient less than a specified gradient threshold during the execution of the constant speed driving control, i.e., when the downhill is slow compared to a downhill with the specified gradient threshold, and the braking force generated by the brake pads pressing against the brake discs of the vehicle is continuously applied to the vehicle for a long period of time, the constant speed driving control is interrupted and intermittent braking control is executed. The intermittent braking control repeatedly performs intermittent braking and stops the intermittent braking, and the intermittent braking applies a larger braking force to the vehicle compared to the braking force applied to the vehicle by the constant speed driving control.

6. A vehicle driving assistance program product, comprising a vehicle driving assistance program that performs cruise control, wherein the cruise control autonomously controls the vehicle's speed to a set speed. The vehicle driving assistance program is configured to, during the execution of the cruise control, when the vehicle is traveling downhill with a gradient less than a specified gradient threshold (i.e., the downhill is slower than a downhill with the specified gradient threshold), continuously apply braking force generated by the vehicle's brake pads pressing against the vehicle's brake disc for an extended period of time, interrupt the cruise control and execute intermittent braking control. The intermittent braking control repeatedly applies intermittent braking and stops the intermittent braking, and the intermittent braking applies a larger braking force to the vehicle than the braking force applied to the vehicle by the cruise control.

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