Drive support device

Abstract

To suppress acceleration and deceleration unintended by a driver.SOLUTION: A vehicle of the present invention has an ACC function of performing constant-speed traveling according to a target vehicle speed if there is no preceding vehicle, and performing following traveling while maintaining a predetermined intervehicle distance if there is a preceding vehicle. A drive support device 10 includes a control part 21 that, when the ACC function is executed and a predetermined condition is satisfied, performs control to cause the vehicle to travel on the basis of a result of learning of acceleration and deceleration operation according to an intervehicle distance of own vehicle and a preceding vehicle performed by a driver of own vehicle. Since the vehicle is caused to travel on the basis of a result of learning the acceleration and deceleration operation according to the intervehicle distance between own vehicle and the preceding vehicle by the driver of own vehicle, acceleration and deceleration unintended by the driver can be suppressed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a driving assistance device. [Background technology]

[0002] Vehicles equipped with an adaptive cruise control (hereinafter referred to as ACC) function have been known for some time. Patent Document 1 discloses a vehicle driving control device having a cruise control means for controlling the drive mechanism of the vehicle in accordance with two control modes: a set vehicle speed mode in which the vehicle is controlled to maintain a vehicle speed command set by the driver, and a follow mode in which the vehicle is controlled to maintain the distance to an object ahead at a vehicle distance command value. In the follow mode, if the currently measured distance to the preceding vehicle is greater by a predetermined value than the previously measured distance, the cruise control means transitions the control mode from the follow mode to a set vehicle speed mode in which the current vehicle speed is used as the vehicle speed command. Furthermore, the cruise control means transitions from the set vehicle speed mode to the follow mode when the distance to the preceding vehicle becomes shorter than the predetermined distance or when the preceding vehicle approaches the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-85406 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with conventional technology, when the ACC function is running, if there is no vehicle ahead of the vehicle or another vehicle enters in front of the vehicle, the automatic control can cause the vehicle to accelerate or decelerate unintentionally, in a way that the driver would not normally do.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has as its object to suppress unintended acceleration and deceleration by the driver. [Means for solving the problem]

[0006] The present invention is a driving assistance device for a vehicle having an ACC function that drives at a constant speed according to a target vehicle speed when there is no vehicle in front, and follows a vehicle in front while maintaining a specified distance between the vehicles.The device is characterized by having a control unit that, when the ACC function is executed and specified conditions are met, controls the vehicle to drive based on the results of learning the acceleration and deceleration operations performed by the driver of the vehicle in question according to the distance between the vehicle and the vehicle in front. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress acceleration and deceleration unintended by the driver. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of a driving assistance device. [Figure 2] 4 is a flowchart illustrating an example of processing performed by the driving assistance device. [Figure 3] FIG. 10 is a diagram showing an example of a portion of learning data obtained by learning acceleration / deceleration operations. DETAILED DESCRIPTION OF THE INVENTION

[0009] A vehicle according to an embodiment of the present invention has an ACC function that drives at a constant speed according to a target vehicle speed when there is no vehicle ahead, and follows a vehicle ahead while maintaining a predetermined distance. The driving assistance device 10 includes a control unit 21 that, when the ACC function is executed and predetermined conditions are met, controls the vehicle to drive based on the results of learning the acceleration / deceleration operation performed by the driver of the vehicle according to the distance between the vehicle ahead and the vehicle ahead. Because the vehicle is driven based on the results of learning the acceleration / deceleration operation performed by the driver of the vehicle according to the distance between the vehicle ahead and the vehicle ahead, unintended acceleration / deceleration by the driver can be suppressed. [Example]

[0010] A driving assistance device 10 according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of a driving assistance device 10. As shown in FIG. The driving assistance device 10 is installed in a vehicle in which a driver rides. The vehicle in which the driving assistance device 10 is installed is equipped with devices that are equipped in a general vehicle, and illustrations and descriptions of these devices will be omitted as appropriate.

[0011] The driving assistance device 10 according to the embodiment includes a controller 20, various input devices 30, and various output devices 40. The controller 20 controls the driving assistance device 10. The controller 20 may also function as a control device that controls the vehicle, or may be a device different from the control device that controls the vehicle. Furthermore, the controller 20 may be configured, for example, by one ECU (Electronic Control Unit), or by multiple ECUs working together.

[0012] The controller 20 has a control unit 21. The control unit 21 controls various output devices 40 based on information input from various input devices 30 to execute the ACC function or to perform processing in accordance with the driver's operation without executing the ACC function. Here, the ACC function is a function that drives the vehicle at a constant speed according to a target vehicle speed when there is no vehicle ahead, and follows the vehicle ahead while maintaining a predetermined distance when there is a vehicle ahead. Note that each process performed by the control unit 21 is realized by the control unit 21 executing a program stored in the controller 20. In addition to the program, the controller 20 also stores various information required for the control unit 21 to execute the program.

[0013] The driving assistance device 10 includes, as input devices 30, a vehicle-in-front detection unit 31, an accelerator pedal operation detection unit 32, a brake pedal operation detection unit 33, a vehicle speed sensor 34, a position information acquisition unit 35, an operation unit 36, and the like.

[0014] The vehicle-in-front detection unit 31 detects vehicles in front. For example, a millimeter-wave radar or a camera is used for the vehicle-in-front detection unit 31. The millimeter-wave radar detects the inter-vehicle distance and the relative speed between the host vehicle and the vehicle in front based on the reflected information from the millimeter-wave radar that is emitted ahead of the host vehicle. The camera detects the inter-vehicle distance and the relative speed between the host vehicle and the vehicle in front based on an image captured in front of the host vehicle. The information detected by the vehicle-in-front detection unit 31 is input to the controller 20. The controller 20 may also detect the inter-vehicle distance and the relative speed between the host vehicle and the vehicle in front based on the information detected by the vehicle-in-front detection unit 31.

[0015] Accelerator pedal operation detection unit 32 detects the driver's operation of the accelerator pedal. For example, an accelerator pedal stroke sensor is used as accelerator pedal operation detection unit 32. Accelerator pedal operation detection unit 32 detects the amount of depression of the accelerator pedal and the acceleration when depression occurs (depression acceleration). Information detected by accelerator pedal operation detection unit 32 is input to controller 20. Note that controller 20 may detect the amount of depression of the accelerator pedal and the depression acceleration based on the information detected by accelerator pedal operation detection unit 32.

[0016] The brake pedal operation detection unit 33 detects the driver's operation of the brake pedal. For example, a brake pedal stroke sensor is used as the brake pedal operation detection unit 33. The brake pedal operation detection unit 33 detects the amount of depression of the brake pedal and the acceleration (depression acceleration) when the brake pedal is depressed. Information detected by the brake pedal operation detection unit 33 is input to the controller 20. Note that the controller 20 may detect the amount of depression of the brake pedal and the depressing acceleration based on the information detected by the brake pedal operation detection unit 33.

[0017] The vehicle speed sensor 34 is a sensor that detects the speed of the host vehicle. For example, a pulse sensor is used as the vehicle speed sensor 34. Information detected by the vehicle speed sensor 34 is input to the controller 20. Note that the controller 20 may detect the speed of the host vehicle based on the information detected by the vehicle speed sensor 34.

[0018] The position information acquisition unit 35 acquires position information of the vehicle. Specifically, the position information acquisition unit 35 acquires the position information of the vehicle by calculating latitude and longitude based on radio waves received from GPS satellites or by acquiring latitude and longitude information from a base station. The information acquired by the position information acquisition unit 35 is input to the controller 20. Note that the controller 20 may acquire the position information of the vehicle based on the information acquired by the position information acquisition unit 35.

[0019] The operation unit 36 is a part that the driver (including passengers) operates to give instructions to the controller 20. The operation unit 36 may be, for example, physical switches and buttons located around the driver's seat, or may be switches and buttons displayed on a display around the driver's seat. The operation unit 36 may also be, for example, a mobile communication terminal such as a smartphone connected to the controller 20 so as to be able to communicate with it.

[0020] In this embodiment, the driver can use the operation unit 36 to input an ON or OFF command for the ACC function, which causes the controller 20 to execute or stop the ACC function. Furthermore, if there is no vehicle ahead while the ACC function is being executed, the driver can use the operation unit 36 to input information about a target vehicle speed when the host vehicle is traveling at a constant speed. Furthermore, if there is a vehicle ahead while the ACC function is being executed, the driver can use the operation unit 36 to input information about a target inter-vehicle distance from the vehicle ahead when following the vehicle ahead. The information input via the operation unit 36 is stored in the controller 20.

[0021] The driving assistance device 10 has, as output devices 40, a driving source 41, a brake system 42, and the like. The drive source 41 is a power unit for driving the vehicle. For example, an engine, an electric motor, or the like is used as the drive source 41. The power from the drive source 41 is transmitted to the wheels via a transmission or a power transmission device, thereby causing the vehicle to run. The drive source 41 is controlled by the control unit 21. Note that the controller 20 may have a drive control unit for controlling the drive source 41 separately from the control unit 21.

[0022] The brake system 42 is a system for braking a running vehicle. For example, the brake system 42 generates hydraulic pressure in the master cylinder by an actuator according to the depression amount of the brake pedal, and operates the brake main body by the generated hydraulic pressure to brake the wheels. The brake system 42 is controlled by the control unit 21. Note that the controller 20 may have a brake control unit for controlling the brake system 42 separately from the control unit 21.

[0023] Next, the processing performed by the control unit 21 of the controller 20 will be briefly described when the ACC function is not executed (non-execution of the ACC function) and when the ACC function is executed (execution of the ACC function) in the driving support device 10 configured as described above. <Non-execution of the ACC function> When the ACC function is not executed, the control unit 21 controls the drive source 41 so as to output according to the depression amount and depression acceleration of the accelerator pedal detected by the accelerator pedal operation detection unit 32. Further, the control unit 21 controls the brake system 42 so that the vehicle is braked according to the depression amount and depression acceleration of the brake pedal detected by the brake pedal operation detection unit 33. Therefore, when the ACC function is not executed, the control unit 21 controls the drive source 41 and the brake system 42 based on the driver's accelerator pedal operation and brake pedal operation.

[0024] <Execution of the ACC function> When the ACC function is being executed, the control unit 21 drives the vehicle at a constant speed according to the target vehicle speed if there is no vehicle ahead, and drives the vehicle ahead while maintaining a predetermined distance from the vehicle ahead if there is a vehicle ahead. Therefore, the control unit 21 can assist the driver in driving so as to reduce the burden on the driver of operating the accelerator pedal and the brake pedal. Here, the ACC function of this embodiment is provided with two control modes (normal control mode and learning control mode).

[0025] [Normal control mode] The normal control mode is a mode in which the control unit 21 controls the drive source 41 and the brake system 42 based on preset values set when the vehicle is manufactured. When it is determined that there is no vehicle ahead, the control unit 21 controls the drive source 41 and the brake system 42 so that the vehicle speed of the vehicle becomes the input target vehicle speed even without operation of the accelerator pedal or the brake pedal (constant speed method). At this time, the control unit 21 controls the drive source 41 and the brake system 42 to accelerate and decelerate the vehicle until the target vehicle speed is reached based on preset values set at the time of vehicle manufacture.

[0026] On the other hand, when it is determined that there is a vehicle ahead, control unit 21 controls drive source 41 and brake system 42 so that the inter-vehicle distance becomes the input target inter-vehicle distance even without accelerator pedal operation or brake pedal operation (follow-up method). Specifically, when the inter-vehicle distance detected by leading vehicle detection unit 31 is greater than the target inter-vehicle distance, control unit 21 controls drive source 41 by increasing the output of drive source 41 so that the target inter-vehicle distance becomes the target. Conversely, when the inter-vehicle distance detected by leading vehicle detection unit 31 is smaller than the target inter-vehicle distance, control unit 21 controls drive source 41 and brake system 42 by reducing the output of drive source 41 or braking the vehicle so that the target inter-vehicle distance becomes the target. At this time, control unit 21 controls drive source 41 and brake system 42 to determine the acceleration and deceleration of the vehicle until the target inter-vehicle distance is achieved based on setting values preset at the time of vehicle manufacture.

[0027] [Learning control mode] The learning control mode is a mode in which the control unit 21 controls the drive source 41 and the brake system 42 so that the vehicle travels based on the results (learned values) of learning the acceleration and deceleration operations performed by the driver of the vehicle according to the distance between the vehicle and the vehicle in front.

[0028] When it is determined that there is no vehicle ahead, the control unit 21 controls the drive source 41 and the brake system 42 so that the vehicle speed of the vehicle becomes the input target vehicle speed even without operation of the accelerator pedal or the brake pedal (constant speed method). At this time, the control unit 21 controls the drive source 41 and the brake system 42 based on the learned value to adjust the acceleration and deceleration of the vehicle until the target vehicle speed is reached.

[0029] On the other hand, when it is determined that there is a vehicle ahead, the control unit 21 controls the driving source 41 and the braking system 42 so that the inter-vehicle distance becomes the input target inter-vehicle distance even without operation of the accelerator pedal or the brake pedal (follow-up method). At this time, the control unit 21 controls the driving source 41 and the braking system 42 based on the learned values to adjust the vehicle acceleration and deceleration until the target inter-vehicle distance is reached. In this way, the vehicle is driven based on the learned value, so that unintended acceleration or deceleration by the driver can be suppressed.

[0030] Next, a specific process for suppressing unintended acceleration or deceleration by the driving assistance device 10 will be described with reference to the flowchart of Fig. 2. The flowchart of Fig. 2 is implemented by the control unit 21 executing a program stored in the controller 20. The flowchart of Fig. 2 starts when the controller 20 is started via the operation unit 36, and ends when the controller 20 is stopped via the operation unit 36.

[0031] In S10, the control unit 21 determines whether or not to execute the ACC function. Specifically, the control unit 21 determines to execute the ACC function if the driver turns on the ACC function via the operation unit 36, and determines not to execute the ACC function if the driver does not turn on the ACC function. If the ACC function is to be executed, the process proceeds to S12, and if the ACC function is not to be executed, the process proceeds to S11.

[0032] In S11, the control unit 21 learns the acceleration / deceleration operation by the driver of the host vehicle according to the distance between the host vehicle and the vehicle in front. Here, since the ACC function is not executed when proceeding to S11, the driver drives the vehicle while operating the accelerator pedal and the brake pedal according to the distance between the host vehicle and the vehicle in front, etc. The control unit 21 controls the drive source 41 and the brake system 42 based on the driver's operation of the accelerator pedal and the brake pedal.

[0033] At this time, control unit 21 acquires information about the speed of the host vehicle from vehicle speed sensor 34, and acquires information about the distance between the host vehicle and the vehicle in front from leading vehicle detection unit 31. Control unit 21 also acquires and stores information about acceleration and deceleration operations by the driver while driving at the acquired vehicle speed and distance, thereby learning acceleration and deceleration operations. Specifically, control unit 21 acquires information about accelerator pedal operation from accelerator pedal operation detection unit 32, and acquires information about brake pedal operation by the driver from brake pedal operation detection unit 33 and stores it in controller 20.

[0034] 3 is a diagram showing an example of a portion of learning data 50, which is the result of learning the driver's acceleration / deceleration operations. The learning data 50 is divided into highway driving and general road driving, and the accelerator pedal depression amount, accelerator acceleration, brake depression amount, and brake acceleration are stored as learned values for each inter-vehicle distance divided into predetermined ranges.

[0035] "When driving on a highway" shown in FIG. 3 is a learned value learned when driving at high speed, and "when driving on a general road" is a learned value learned when driving at low speed. The control unit 21 can determine whether the vehicle is driving at high speed or low speed by comparing the vehicle speed of the host vehicle acquired from the vehicle speed sensor 34 with a threshold vehicle speed. Note that the control unit 21 can determine whether the vehicle is driving on a highway or a general road based on the information input by the position information acquisition unit 35 and the road information stored in the controller 20, and may learn separately for when driving on a highway and when driving on a general road. "Inter-vehicle distance L [m]" shown in FIG. 3 is the inter-vehicle distance between the host vehicle and the preceding vehicle, and has the relationship of Lmin < Lmin+1 < Lmin+2 < Ln < Ln+1 < Lmax-2 < Lmax-1 < Lmax.

[0036] "Accelerator pedal depression amount" shown in FIG. 3 is the average value of the depression amount when the accelerator pedal is depressed, and "accelerator acceleration" is the average value of the acceleration of the accelerator pedal until reaching the depression amount. When "accelerator acceleration" is large, it means that the driver operates the accelerator pedal quickly, and when "accelerator acceleration" is small, it means that the driver operates the accelerator pedal gently. Also, "brake pedal depression amount" is the average value of the depression amount when the brake pedal is depressed, and "brake acceleration" is the average value of the acceleration of the brake pedal until reaching the depression amount. When "brake acceleration" is large, it means that the driver operates the brake pedal quickly, and when "brake acceleration" is small, it means that the driver operates the brake pedal gently.

[0037] The learned value 51 is information on acceleration / deceleration operations when the inter-vehicle distance L satisfies Lmin < L ≤ Lmin+1. Here, the depression amount of the brake pedal is S1 and the acceleration of the brake pedal is A1, but since the accelerator pedal is not operated, no other values are stored. The learning value 52 is information on acceleration and deceleration operations when the inter-vehicle distance L satisfies Lmin + 1 < L ≤ Lmin + 2. Here, the depression amount of the brake pedal is S2, and the acceleration of the brake pedal is A2. Since the accelerator pedal is not being operated, no other values are stored. The learning value 53 is information on acceleration and deceleration operations when the inter-vehicle distance L satisfies Ln < L ≤ Ln + 1. Here, the depression amount of the accelerator pedal is S3. Since the change in the depression amount of the accelerator pedal is substantially constant, the acceleration of the accelerator pedal is not stored. Also, since the brake pedal is not being operated, no other values are stored. The learning value 54 is information on acceleration and deceleration operations when the inter-vehicle distance L satisfies Lmax - 2 < L ≤ Lmax - 1. Here, the depression amount of the accelerator pedal is S4, and the acceleration of the accelerator pedal is A4. Since the brake pedal is not being operated, no other values are stored. The learning value 55 is information on acceleration and deceleration operations when the inter-vehicle distance L satisfies Lmax - 1 < L ≤ Lmax. Here, the depression amount of the accelerator pedal is S5, and the acceleration of the accelerator pedal is A5. Since the brake pedal is not being operated, no other values are stored.

[0038] Note that the "accelerator depression amount", "accelerator acceleration", "brake depression amount", and "brake acceleration" of the learning values 51 to 55 shown in FIG. 3 are not limited to the average values, and may be the median values, or may be values calculated by other calculation methods. Also, the learning data 50 shown in FIG. 3 has two speed categories, i.e., when driving on a highway and when driving on a general road, but it may be finely divided for each of a plurality of predetermined vehicle speed ranges, similar to the inter-vehicle distance.

[0039] The control unit 21 returns to S10 after learning the acceleration and deceleration operations by the driver in S11 until the ACC function is executed, and proceeds to S12 when the ACC function is executed. In S12, the control unit 21 executes the ACC function and determines whether or not the host vehicle needs to avoid the collision. Specifically, the control unit 21 determines that the host vehicle needs to avoid the collision when another vehicle suddenly cuts in between the host vehicle and the vehicle in front, causing the inter-vehicle distance between the host vehicle and the other vehicle (the new vehicle in front) to become less than a predetermined distance in a short period of time. If the host vehicle needs to avoid the collision, the process proceeds to S18, and if the host vehicle does not need to avoid the collision, the process proceeds to S13.

[0040] In S13, the control unit 21 executes the ACC function in the learning control mode. Specifically, the control unit 21 reads various information such as learning values stored in the controller 20 and executes the ACC function.

[0041] In S14, the control unit 21 determines whether the inter-vehicle distance to the vehicle in front is within a certain distance based on information input from the vehicle-in-front detection unit 31. Information about the certain distance is stored in the controller 20 in advance. The certain distance is a distance that is used as a reference (threshold) when determining whether to travel in a following mode in which the vehicle travels so that the inter-vehicle distance becomes a target inter-vehicle distance, or in a constant speed mode in which the vehicle travels at a constant speed according to a target vehicle speed. The control unit 21 controls the vehicle to travel in the following mode when the inter-vehicle distance from the vehicle in front is within the certain distance, and controls the vehicle to travel in the constant speed mode when the inter-vehicle distance from the vehicle in front is not within the certain distance. If it is within the fixed distance, the process proceeds to S15, and if it is not within the fixed distance, the process proceeds to S16.

[0042] In S15, the control unit 21 determines whether the vehicle in front is traveling within the allowable constant vehicle speed based on information input from the vehicle-in-front detection unit 31. Information on the allowable constant vehicle speed is stored in advance in the controller 20. If the vehicle in front is traveling within the allowable constant vehicle speed, the process proceeds to S16, and if the vehicle in front is not traveling within the allowable constant vehicle speed, the process proceeds to S17.

[0043] In S16, the control unit 21 controls the driving source 41 and the braking system 42 so as to run the vehicle in the learning control mode. Specifically, the control unit 21 controls the driving source 41 and the braking system 42 so as to run the vehicle based on the results of learning the acceleration / deceleration operation by the driver (learned value). Note that in S16, there are two cases where the process proceeds to S16: from S14 to S16 and from S15 to S16; therefore, the following explanation will be divided into two cases.

[0044] When the vehicle proceeds from S14 to S16, the distance between the vehicle and the vehicle in front is not within a certain distance, and corresponds to the case where there is no vehicle in front, so the control unit 21 controls the drive source 41 and the brake system 42 in a constant speed mode, i.e., so that the vehicle speed of the vehicle becomes the target vehicle speed input by the driver. At this time, the control unit 21 controls the driving source 41 and the brake system 42 to change the vehicle acceleration and deceleration from the current vehicle speed to the target vehicle speed based on the learned values. For example, when the host vehicle is traveling at high speed and accelerating to reach the target vehicle speed, the control unit 21 controls the driving source 41 so that the acceleration of the accelerator pedal becomes one of the learned values 54, 55 (e.g., the learned value 55 associated with the largest inter-vehicle distance) stored in the learning data 50 of Fig. 3 for the accelerator acceleration. On the other hand, when the host vehicle is traveling at high speed and decelerating to reach the target vehicle speed, the control unit 21 controls the driving source 41 and the brake system 42 so that the acceleration of the brake pedal becomes one of the learned values 51, 52 (e.g., the learned value 51 associated with the smallest inter-vehicle distance) stored in the learning data 50 of Fig. 3 for the brake acceleration. In this way, by controlling the drive source 41 and the brake system 42 to accelerate and decelerate until the target vehicle speed is reached based on learned values obtained from the driver's acceleration and deceleration operations, it is possible to suppress unintended acceleration and deceleration by the driver.

[0045] On the other hand, when the vehicle proceeds from S15 to S16, the distance between the vehicle and the vehicle in front is within a certain distance, which corresponds to the case where there is a vehicle in front, so the control unit 21 controls the drive source 41 and the brake system 42 in a following mode, i.e., so that the distance between the vehicle and the vehicle in front becomes the target distance input by the driver. At this time, control unit 21 controls drive source 41 and brake system 42 to change the vehicle acceleration and deceleration from the current inter-vehicle distance to the target inter-vehicle distance based on the learned values. For example, when the host vehicle is traveling at high speed and accelerating to achieve the target inter-vehicle distance, control unit 21 controls drive source 41 so that the acceleration of the accelerator pedal becomes the learned value associated with the current inter-vehicle distance among learned values 54 and 55 in which accelerator acceleration is stored among learned data 50 in Fig. 3. On the other hand, when the host vehicle is traveling at high speed and decelerating to achieve the target inter-vehicle distance, control unit 21 controls drive source 41 and brake system 42 so that the acceleration of the brake pedal becomes the learned value associated with the current inter-vehicle distance among learned values 51 and 52 in which brake acceleration is stored among learned data 50 in Fig. 3. In this way, by controlling the driving source 41 and the brake system 42 to accelerate and decelerate until the target inter-vehicle distance is achieved based on learned values of the driver's acceleration and deceleration operations, it is possible to suppress unintended acceleration and deceleration by the driver. In particular, even if there is no vehicle ahead of the host vehicle or another vehicle enters in front of the host vehicle, the vehicle continues to travel in the same way as the driver normally accelerates and decelerates, thereby suppressing unintended acceleration and deceleration by the driver. After S16 is executed, the process returns to S10.

[0046] In S17, the control unit 21 calculates a target vehicle speed for the host vehicle based on the speed of the vehicle ahead and controls the drive source 41 and the brake system 42 to travel at the calculated target vehicle speed. When the process proceeds to S17, the vehicle ahead is not traveling within the allowable constant vehicle speed. In this case, if the control unit 21 were to control the drive source 41 and the brake system 42 in a following mode, i.e., to control the distance between the host vehicle and the vehicle ahead to the target distance input by the driver, the host vehicle would accelerate or decelerate in accordance with the speed of the vehicle ahead. Therefore, the control unit 21 calculates the target vehicle speed based on the speed of the vehicle ahead and travels at the calculated target vehicle speed, thereby preventing unintended acceleration or deceleration by the driver. Furthermore, the control unit 21 controls the drive source 41 and the brake system 42 to adjust the vehicle acceleration and deceleration from the current vehicle speed to the target vehicle speed based on the learned value, as in S16, thereby preventing unintended acceleration or deceleration by the driver.

[0047] The target vehicle speed calculated in S17 can be, for example, the average vehicle speed of the vehicle ahead. In this case, by setting a lower limit value for the calculated average value, it is possible to prevent the average value from being calculated as 0, making it impossible to travel, when traveling in an urban area or in a traffic jam. Furthermore, it is preferable that the greater the difference between the calculated target vehicle speed and the target vehicle speed input by the driver, the more frequently the control unit 21 calculates and updates the target vehicle speed.

[0048] Furthermore, S17 is not limited to constant speed driving at the target vehicle speed, and the drive source 41 and the brake system 42 may be controlled by setting the target inter-vehicle distance to a distance longer than the target inter-vehicle distance input by the driver. In this way, by setting the target inter-vehicle distance to a distance longer than the target inter-vehicle distance input by the driver, it is possible to prevent the inter-vehicle distance from becoming too close and causing anxiety to the driver. After S17 is executed, the process returns to S10.

[0049] Next, when the process proceeds from S12 to S18, the control unit 21 executes the ACC function in the normal control mode. Specifically, the control unit 21 reads various information such as setting values that were previously set at the time of vehicle manufacture and that are stored in the controller 20. In S19, control unit 21 controls drive source 41 and brake system 42 to run the vehicle in the normal control mode. Specifically, control unit 21 controls drive source 41 and brake system 42 to run the vehicle based on preset settings set at the time of vehicle manufacture, rather than on learned values obtained by learning the driver's acceleration / deceleration operations. Therefore, even if a vehicle suddenly cuts in between the host vehicle and a vehicle in front, control unit 21 can perform emergency avoidance of the host vehicle. After S19 is executed, the process returns to S10.

[0050] In this embodiment, the control unit 21 executes the ACC function, and when a predetermined condition is satisfied, controls the drive source 41 and the brake system 42 so that the vehicle travels based on the learned results of the acceleration / deceleration operation performed by the driver of the vehicle in question in accordance with the distance between the vehicle and the vehicle in front (S16). Therefore, because the vehicle travels based on the learned results of the acceleration / deceleration operation performed by the driver of the vehicle in question in accordance with the distance between the vehicle and the vehicle in front, it is possible to suppress acceleration / deceleration unintended by the driver. The predetermined condition in this embodiment is a condition that the distance between the vehicle and the vehicle in front is not within a certain distance in S14. Alternatively, the predetermined condition in this embodiment is a condition that the distance between the vehicle and the vehicle in front is within a certain distance in S14 and that the vehicle in front is traveling within an allowable certain vehicle speed in S15. However, the predetermined condition may be other conditions, or may be a condition to which other conditions are further added.

[0051] Furthermore, in this embodiment, when the vehicle ahead is not traveling within the allowable constant vehicle speed, the control unit 21 calculates a target vehicle speed for the host vehicle based on the vehicle speed of the vehicle ahead, and controls the drive source 41 and the brake system 42 to cause the host vehicle to travel at the calculated target vehicle speed (S17). Therefore, even when the vehicle ahead is not traveling within the allowable constant vehicle speed, the host vehicle can continue to travel at a constant speed, thereby suppressing unintended acceleration or deceleration by the driver. Furthermore, since the host vehicle continues to travel at a constant speed, fuel efficiency can be improved.

[0052] In this embodiment, when the ACC function is executed and another vehicle suddenly cuts in front of the host vehicle, the control unit 21 controls the drive source 41 and the brake system 42 in normal ACC control, that is, normal control mode, which causes the host vehicle to travel based on preset settings set at the time of vehicle manufacture (S19). Therefore, even if another vehicle suddenly cuts in front of the host vehicle, the host vehicle can avoid an emergency by traveling based on the preset settings set at the time of vehicle manufacture.

[0053] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and modifications and the like are possible within the scope of the present invention. If there is a possibility that one vehicle will be driven by multiple different drivers, the control unit 21 may identify the driver based on driver information input via the operation unit 36, or may identify the driver using an in-vehicle camera (not shown). If the control unit 21 can identify the driver, it can learn acceleration / deceleration operations for each driver's identification information, thereby suppressing unintended acceleration / deceleration for each driver.

[0054] In addition to the acceleration / deceleration operation performed by the driver of the host vehicle in accordance with the inter-vehicle distance between the host vehicle and the vehicle in front, the control unit 21 may also learn the inter-vehicle distance between the host vehicle and the vehicle in front. A minimum inter-vehicle distance is pre-stored in the controller 20. The control unit 21 calculates the inter-vehicle distance that the driver often maintains, and if the calculated inter-vehicle distance is equal to or greater than the minimum inter-vehicle distance, sets the calculated inter-vehicle distance as the learned inter-vehicle distance. If the calculated inter-vehicle distance is less than the minimum inter-vehicle distance, the control unit 21 sets the pre-stored minimum inter-vehicle distance as the learned inter-vehicle distance. In S11, the control unit 21 learns the learned inter-vehicle distance according to the speed of the host vehicle, and learns acceleration / deceleration operations required to achieve the learned inter-vehicle distance from a driving state with a different inter-vehicle distance than the learned inter-vehicle distance. If the inter-vehicle distance between the host vehicle and the vehicle in front differs from the learned inter-vehicle distance for the current speed of the host vehicle, the control unit 21 sets the learned inter-vehicle distance as the target inter-vehicle distance, and controls the drive source 41 and the brake system 42 to achieve the target inter-vehicle distance based on the learned vehicle acceleration and deceleration. [Explanation of symbols]

[0055] 10: Driving assistance device 20: Controller 21: Control unit 31: Leading vehicle detection unit 32: Accelerator pedal operation detection unit 33: Brake pedal operation detection unit 34: Vehicle speed sensor 35: Position information acquisition unit 36: Operation unit 41: Drive source 42: Brake system 50: Learning data

Claims

1. A driving assistance device for a vehicle having an ACC function that drives at a constant speed according to a target vehicle speed when there is no vehicle ahead, and drives in pursuit of a vehicle ahead while maintaining a predetermined distance between the vehicles, A driving assistance device characterized by comprising a control unit that controls the vehicle to travel based on the results of learning the acceleration / deceleration operations performed by the driver of the vehicle in question according to the distance between the vehicle and a vehicle in front when the ACC function is executed and predetermined conditions are met.

2. The control unit 2. The driving assistance device according to claim 1, wherein, when the vehicle ahead is not traveling within an allowable constant vehicle speed, a target vehicle speed of the vehicle is calculated based on the vehicle speed of the vehicle ahead, and the vehicle is controlled to travel at a constant speed at the calculated target vehicle speed.

3. The control unit 3. The driving assistance device according to claim 1, wherein when the ACC function is executed and another vehicle suddenly cuts in front of the host vehicle, the driving assistance device controls the host vehicle to run in a normal ACC control mode based on a preset value set at the time of vehicle manufacture.

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