Travel control apparatus

Abstract

To provide a travel control apparatus for executing deceleration control during curve traveling, the travel control apparatus being improved so as to be capable of reducing, even when there is a following vehicle behind an own vehicle, a possibility that drivers of an own vehicle and the following vehicle feel uneasy.SOLUTION: A travel control apparatus includes: an automatic braking device for automatically braking an own vehicle; and a driving support ECU for acquiring information on a curvature of a traveling road in front of the own vehicle (S10), calculating a target vehicle speed Vt of the own vehicle on the basis of the curvature of the traveling road (S30), and executing, when a vehicle speed V of the own vehicle exceeds the target vehicle speed (S40), automatic deceleration of the own vehicle by the automatic braking device so that the vehicle speed of the own vehicle reaches the target vehicle speed (S80). The driving support ECU acquires information behind the own vehicle. When there is a following vehicle behind the own vehicle (S50), the driving support ECU calculates an inter-vehicle time Ti between the own vehicle and the following vehicle (S60). When the inter-vehicle time is less than a reference value Tic, the driving support ECU does not execute the automatic deceleration of the own vehicle (S70).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a cruise control device for a vehicle such as an automobile, which controls deceleration when traveling around a curve. [Background technology]

[0002] As one type of cruise control device for vehicles such as automobiles, there is known a cruise control device that performs deceleration control when traveling around a curve. In the deceleration control when traveling around a curve, a target vehicle speed of the vehicle is calculated based on the curvature of the road ahead of the vehicle, and when the vehicle speed exceeds the target vehicle speed, the vehicle is decelerated by automatic braking so that the vehicle speed becomes the target vehicle speed.

[0003] For example, the following Patent Document 1 describes a cruise control device that, when the vehicle speed exceeds a vehicle speed specified for a curve, automatically brakes the vehicle to decelerate so that the vehicle speed when traveling around a curve increases as the control vehicle speed set by the cruise control increases. This type of cruise control device can provide driving assistance to prevent the vehicle speed from becoming excessive when traveling around a curve. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7104649 specification Summary of the Invention

[0005] [Problem to be solved by the invention] However, in conventional cruise control devices such as the device described in Patent Document 1, when the vehicle speed exceeds a target vehicle speed, the vehicle is decelerated by automatic braking without considering the effect that the deceleration of the vehicle will have on the rear of the vehicle. Therefore, if the host vehicle is decelerated in a situation where there is a following vehicle behind the host vehicle and the inter-vehicle distance, particularly the inter-vehicle time, between the host vehicle and the following vehicle is small, the host vehicle and the following vehicle may become excessively close to each other due to the deceleration of the host vehicle, which may cause the drivers of the host vehicle and the following vehicle to feel uneasy.

[0006] The present invention provides a driving control device that performs deceleration control when driving around a curve, and is improved so as to reduce the risk of the drivers of the vehicle and the following vehicle feeling uneasy even when there is a following vehicle behind the vehicle. [Means for solving the problems and effects of the invention]

[0007] According to the present invention, there is provided a driving control device (100) including an automatic braking device (36) that automatically brakes a host vehicle (102), and a control unit (driving assistance ECU 10) configured to acquire (S10) information on the curvature of a road ahead of the host vehicle, calculate (S30) a target vehicle speed (Vt) of the host vehicle based on the curvature of the road, and, when the vehicle speed (V) of the host vehicle exceeds the target vehicle speed (S40), automatically decelerate the host vehicle by the automatic braking device so that the vehicle speed of the host vehicle becomes the target vehicle speed (S80).

[0008] The control unit (driving assistance ECU10) is configured to obtain information behind the host vehicle, and when there is a following vehicle behind the host vehicle (S50), calculate the inter-vehicle time (Ti) between the host vehicle and the following vehicle (S60), and when the inter-vehicle time is less than a reference value (Tic), not to automatically decelerate the host vehicle (S70).

[0009] According to the above configuration, information on the curvature of the road ahead of the host vehicle is acquired, a target vehicle speed of the host vehicle is calculated based on the curvature of the road, and when the vehicle speed of the host vehicle exceeds the target vehicle speed, the automatic braking device decelerates the host vehicle so that the vehicle speed of the host vehicle becomes the target vehicle speed. Furthermore, information on the rear of the host vehicle is acquired, and when there is a following vehicle behind the host vehicle, the inter-vehicle time between the host vehicle and the following vehicle is calculated, and when the inter-vehicle time is less than a reference value, the automatic braking device does not decelerate the host vehicle.

[0010] Therefore, when there is a following vehicle behind the host vehicle and the inter-vehicle time between the host vehicle and the following vehicle is less than the reference value, the host vehicle is not decelerated, thereby reducing the risk that the drivers of the host vehicle and the following vehicle will feel uneasy due to the host vehicle and the following vehicle coming too close to each other due to the deceleration of the host vehicle.

[0011] When there is no following vehicle behind the host vehicle, or when there is a following vehicle behind the host vehicle but the inter-vehicle time between the host vehicle and the following vehicle is equal to or greater than a reference value, and the host vehicle speed exceeds the target vehicle speed, the host vehicle is decelerated so that its speed becomes the target vehicle speed. Therefore, driving assistance can be provided to prevent the host vehicle from going too fast when traveling around a curve.

[0012] In the above description, other objects, other features and attendant advantages of the present invention will be easily understood from the following description of the embodiments of the present invention which will be described with reference to the drawings. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram showing a driving control device according to an embodiment; [Diagram 2] 5 is a flowchart corresponding to a deceleration control program when traveling along a curve in the embodiment. [Diagram 3] 1A and 1B are diagrams illustrating deceleration control when traveling around a curve in cases where the inter-vehicle time between the vehicle and the following vehicle is less than a reference value (A) and is equal to or greater than the reference value (B). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a cruise control device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0015] As shown in Fig. 1, a cruise control device 100 according to an embodiment of the present invention is applied to a vehicle 102 and includes a driving assistance ECU 10. The vehicle 102 is an autonomous vehicle and includes a drive ECU 20, a braking ECU 30, an electric power steering ECU 40, and a meter ECU 50. ECU refers to an electronic control unit (Electronic Control Unit) that includes a microcomputer as a main component. In the following description, the electric power steering is referred to as EPS.

[0016] The microcomputer of each ECU includes a CPU, ROM, RAM, a readable / writable non-volatile memory (N / M), and an interface (I / F). The CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. Furthermore, these ECUs are connected to each other via a Controller Area Network (CAN) 104 so that they can exchange data (communicate). Therefore, the detection values ​​of sensors (including switches) connected to a specific ECU are also sent to other ECUs.

[0017] The driving assistance ECU 10 is a central control device that performs driving control for driving assistance such as deceleration control when driving around a curve, lane keeping control, etc. In the embodiment, the driving assistance ECU 10 executes deceleration control when the vehicle 102 is driving around a curve in cooperation with other ECUs, as will be described in detail later.

[0018] The driving assistance ECU 10 is connected to a camera sensor 12, a radar sensor 14, and a setting operation device 16. The camera sensor 12 and the radar sensor 14 each include a plurality of camera devices and a plurality of radar devices. The camera sensor 12 and the radar sensor 14 function as a target information acquisition device 18 that acquires target information around the vehicle 102. Note that instead of or in addition to the radar sensor 14, a LiDAR (Light Detection And Ranging) may be used.

[0019] The setting operation device 16 is provided at a position operable by the driver, like a steering wheel (not shown in Fig. 1), and is adapted to be operated by the driver. Although not shown in Fig. 1, the setting operation device 16 includes a driving assistance switch. As will be described in detail later, when the driving assistance switch is on, the driving assistance ECU 10 executes deceleration control when driving around a curve.

[0020] The drive ECU 20 is connected to a drive device 22 that accelerates the vehicle 102 by applying a drive force to drive wheels 24. The drive ECU 20 normally controls the drive device 22 so that the drive force generated by the drive device 22 changes according to the driving operation by the driver, and when a command signal is received from the driving assistance ECU 10, the drive ECU 20 controls the drive device 22 based on the command signal.

[0021] A braking device 32 that applies a braking force to wheels 34 to decelerate the vehicle 102 is connected to the braking ECU 30. The braking ECU 30 normally controls the braking device so that the braking force generated by the braking device 32 changes according to the braking operation by the driver, and when it receives a command signal from the driving assistance ECU 10, it controls the braking device 32 based on the command signal to perform automatic braking.

[0022] Therefore, the brake ECU 30 and the brake device 32 cooperate with each other to function as an automatic braking device 36. When a braking force is applied to the wheels due to deceleration control when traveling around a curve, a brake lamp (not shown in FIG. 1) is turned on.

[0023] An EPS device 42 is connected to the EPS·ECU 40. The EPS·ECU 40 controls the EPS device 42 in a manner known in the art based on the steering torque and vehicle speed, thereby controlling the steering assist torque and reducing the steering burden on the driver. In addition, the EPS·ECU 40 can steer steered wheels 44 as necessary by controlling the EPS device 42.

[0024] A touch panel type display 52 that displays the status of control by the driving assistance ECU 10 is connected to the meter ECU 50. When the display 52 receives a signal from the driving assistance ECU 10, it displays the status of deceleration control when traveling around a curve.

[0025] The driving operation sensor 60 and the vehicle condition sensor 70 are also connected to the CAN 104. Information detected by the driving operation sensor 60 and the vehicle condition sensor 70 (called sensor information) is transmitted to the CAN 104. The sensor information transmitted to the CAN 104 can be used appropriately in each ECU. Note that the sensor information may be information of a sensor connected to a specific ECU and transmitted to the CAN 104 from the specific ECU.

[0026] The driving operation sensor 60 includes a driving operation amount sensor, a braking operation amount sensor, and a brake switch. The driving operation sensor 60 also includes a steering angle sensor, a steering torque sensor, etc. The vehicle state sensor 70 includes a vehicle speed sensor, a longitudinal acceleration sensor, a lateral acceleration sensor, and a yaw rate sensor, etc.

[0027] Furthermore, a navigation device 80 is also connected to the CAN 104. The navigation device 80 includes a GPS receiver that detects the position of the vehicle 102, a storage device that stores map information and road information, and a communication device that acquires the latest information on the map information and road information from an external device. In particular, the road information may include information on the curvature or curvature radius of a curved road. Note that the navigation device 80 does not necessarily have to be provided.

[0028] In this embodiment, the ROM of the driving assistance ECU 10 stores a deceleration control program for driving around a curve, which corresponds to the flowchart shown in FIG. <Deceleration control when driving on a curve (Fig. 2)>

[0029] Next, deceleration control during curve driving in the embodiment will be described with reference to the flowchart shown in Fig. 2. The deceleration control during curve driving according to the flowchart shown in Fig. 2 is repeatedly executed at predetermined time intervals by the CPU of the driving assistance ECU 10 when the driving assistance switch is on.

[0030] First, in step S10, the CPU calculates the curvature C of the road ahead based on an image of the road ahead of the vehicle 102 captured by the camera sensor 12. The curvature C of the road may be calculated based on road information stored in the navigation device 80, or may be calculated based on curvature information attached to the road information stored in the navigation device 80. The curvature C of the road may be estimated based on the vehicle speed and steering angle, or may be estimated based on a change in the curvature of the lane at the current location estimated based on the vehicle speed and the lateral acceleration of the vehicle. Furthermore, the curvature C of the road may be calculated based on road information transmitted from a communication device installed on the roadside. The curvature C of the road is calculated as a positive value regardless of the direction of the lane curve.

[0031] In step S20, the CPU determines whether the curvature C of the road is equal to or greater than a reference value Cc (a positive constant). If a negative determination is made, the control ends, and if a positive determination is made, the control proceeds to step S30.

[0032] In step S30, the CPU calculates a target vehicle speed Vt when traveling around a curve based on the curvature C of the road so that the target vehicle speed Vt decreases as the curvature C of the road increases. The target vehicle speed Vt may be calculated based on a relationship between the curvature C of the road and the target vehicle speed, which is determined, for example, experimentally or by learning, so that the vehicle can travel around a curve stably and safely. When adaptive vehicle distance control is performed, the target vehicle speed Vt may be calculated to be equal to or lower than a set vehicle speed for adaptive vehicle distance control.

[0033] In step S40, the CPU determines whether or not the vehicle speed V of the host vehicle 102 exceeds the target vehicle speed Vt, that is, whether or not automatic deceleration during curve traveling by the automatic braking device 36 is necessary. If a negative determination is made, this control is temporarily terminated, and if a positive determination is made, this control proceeds to step S50.

[0034] In step S50, the CPU determines whether or not there is a following vehicle in the own lane behind the own vehicle within a reference distance (positive constant) from the own vehicle, based on information behind the own vehicle 102 acquired by the target information acquisition device 18. If the CPU makes a negative determination, the control proceeds to step S80, and if the CPU makes a positive determination, the control proceeds to step S60.

[0035] In step S60, the CPU calculates the inter-vehicle distance Li between the host vehicle and the following vehicle, the vehicle speed Vb of the following vehicle, and the relative vehicle speed Vr of the following vehicle with respect to the host vehicle, based on the information behind the host vehicle 102 acquired by the target information acquisition device 18. Furthermore, the CPU calculates the inter-vehicle time Ti as Li / Vb, and the collision margin time Tt as Li / Vr.

[0036] In step S70, the CPU determines whether the inter-vehicle time Ti is less than a reference time Tic (positive constant) or the collision margin time Tt is less than a reference time Ttc (positive constant). If a positive determination is made, this control is temporarily terminated, and if a negative determination is made, this control proceeds to step S80.

[0037] In step S80, the CPU calculates a target deceleration Gbt for making the vehicle speed V of the host vehicle 102 the target vehicle speed Vt, and executes automatic deceleration control of the host vehicle so that the deceleration of the host vehicle becomes the target deceleration Gbt by outputting a command signal to the brake ECU 30. Note that the target deceleration Gbt may be calculated as a deceleration that makes the vehicle speed V of the host vehicle the target vehicle speed Vt in a pre-set deceleration time.

[0038] As can be seen from the above description, according to the embodiment, information on the curvature C of the road ahead of the host vehicle 102 is acquired (S10), and the target vehicle speed Vt of the host vehicle is calculated based on the curvature of the road (S30). When the vehicle speed V of the host vehicle exceeds the target vehicle speed (S40), the automatic braking device 36 decelerates the host vehicle so that the vehicle speed of the host vehicle becomes the target vehicle speed (S80). Furthermore, information behind the host vehicle is acquired, and when there is a following vehicle behind the host vehicle (S50), the inter-vehicle time Ti and collision margin time Tt between the host vehicle and the following vehicle are calculated (S60), and when the inter-vehicle time is less than the reference value Tic or the collision margin time is less than the reference value Ttc, the automatic braking device does not decelerate the host vehicle (S70).

[0039] 3A, when there is a following vehicle 112 traveling in the host vehicle lane 110 behind the host vehicle 102 and the inter-vehicle time Ti between the host vehicle and the following vehicle is less than the reference value Tic, no braking force Fb is applied to the host vehicle as shown by the dashed line, and the host vehicle is not decelerated. This reduces the risk that the drivers of the host vehicle and the following vehicle will feel uneasy due to the host vehicle and the following vehicle approaching too closely due to the deceleration of the host vehicle.

[0040] When there is no following vehicle behind the host vehicle, or when there is a following vehicle 112 traveling in the host vehicle lane 110 behind the host vehicle 102 but the inter-vehicle time Ti between the host vehicle and the following vehicle is equal to or greater than the reference value Tic as shown in Fig. 3(B), if the host vehicle speed V exceeds the target vehicle speed Vt, a braking force Fb is applied to the host vehicle, and the host vehicle is decelerated so that its speed becomes the target vehicle speed. Therefore, driving assistance can be provided to prevent the host vehicle from going too fast when traveling around a curve.

[0041] In particular, according to the embodiment, the inter-vehicle time Ti and the collision margin time Tt between the host vehicle and the following vehicle are calculated (S60), and when the inter-vehicle time is less than the reference value Tic or the collision margin time is less than the reference value Ttc, the host vehicle is not decelerated by the automatic braking device (S70). Therefore, compared to a case in which the inter-vehicle distance between the host vehicle and the following vehicle is calculated and the inter-vehicle distance is less than the reference inter-vehicle distance, the risk that the drivers of the host vehicle and the following vehicle will feel uneasy due to the host vehicle and the following vehicle approaching too closely due to the deceleration of the host vehicle can be effectively reduced.

[0042] Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various other embodiments are possible within the scope of the present invention.

[0043] For example, in the above embodiment, in step S20, it is determined whether the curvature C of the road is equal to or greater than the reference value Cc, and if a negative determination is made, this control is temporarily terminated. However, if step S20 is omitted and the curvature C of the road is equal to or greater than the reference value Cc, in step S30, the target vehicle speed Vt during curve traveling may be calculated to a value such as 300 km / h that will result in a negative determination in step S40.

[0044] In the above embodiment, it is determined in step S50 whether or not there is a following vehicle in the own lane behind the host vehicle within a reference distance from the host vehicle. However, if step S50 is omitted and there is no following vehicle in the own lane behind the host vehicle within the reference distance from the host vehicle, the inter-vehicle time Ti may be calculated to a value equal to or greater than the reference time Tic in step S60.

[0045] Furthermore, in the above embodiment, the reference time Tic in the determination in step S70 is a positive constant. However, the reference time Tic may be variably set according to the rate of change of the inter-vehicle time Ti, for example, so that the reference time Tic is larger as the decrease rate of the inter-vehicle time Ti is higher and is smaller as the increase rate of the inter-vehicle time Ti is higher.

[0046] Furthermore, in the above embodiment, the curvature C of the road is calculated in step S10, and it is determined in step S20 whether the curvature C of the road is equal to or greater than a reference value Cc. However, it may be possible to calculate the curvature radius R of the road in step S10, and determine in step S20 whether the curvature radius R is equal to or less than a reference value Rc (a positive constant). [Explanation of symbols]

[0047] 10... driving assistance ECU, 12... camera sensor, 14... radar sensor, 18... target detection device, 22... drive device, 32... braking device, 36... automatic braking device, 42... EPS device, 100... driving control device, 102... vehicle, 112... following vehicle

Claims

[Claim 1] A driving control device including an automatic braking device that automatically brakes a host vehicle, and a control unit configured to acquire information on a curvature of a road ahead of the host vehicle, calculate a target vehicle speed of the host vehicle based on the curvature of the road, and, when the vehicle speed of the host vehicle exceeds the target vehicle speed, automatically decelerate the host vehicle by the automatic braking device so that the vehicle speed of the host vehicle becomes the target vehicle speed, The control unit is configured to acquire information behind the host vehicle, and when there is a following vehicle behind the host vehicle, calculate a time gap between the host vehicle and the following vehicle, and when the time gap is less than a reference value, not to automatically decelerate the host vehicle.

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