Vehicle drive assistance device

Abstract

A vehicle drive assistance device according to the present invention comprises a travel control unit that forcibly causes a brake to intervene, wherein: the travel control unit includes a start scenario determination unit and a control intervention determination unit; the start scenario determination unit includes a start acceleration determination processing unit that checks whether or not a subject vehicle is in start acceleration, a control target recognition processing unit that recognizes a moving target approaching from the side in the direction of the subject vehicle as a control target, and a relative information acquisition processing unit that checks whether or not the control target has intruded into an intrusion area defined on the side of the subject vehicle; and the control intervention determination unit forcibly applies the brake via a brake application unit when the subject vehicle is in the start acceleration and determines that the control target has intruded into the intrusion area.

Description

Vehicle driving assistance device

[0001] The present invention relates to a driving assistance device for a vehicle.

[0002] When a vehicle passes through an intersection and there is a possibility of collision with a target such as a vehicle, motorcycle, or bicycle (hereinafter referred to as a "moving target") approaching from the side road, a front cross traffic braking (FCTB) control (also referred to as front cross traffic alert braking (FCTAB)) is known that activates a brake device to avoid the collision.

[0003] For example, in the FCTB control disclosed in International Publication No. 2011 / 064824, a front-side radar mounted on the vehicle first detects whether or not there is a moving target (moving body) approaching from the side. If a moving target is detected, the time until a collision between the vehicle and the moving body (predicted collision time) is calculated. If this predicted collision time is equal to or less than a preset threshold, an automatic brake (AEB: Autonomous Emergency Braking) is activated.

[0004] In the technology disclosed in this document, the predicted time to collision (TTC) is calculated based on the vehicle speed Vm [Km / h] and the relative distance Dx [m] between the vehicle and a moving object (TTC = Vm / Dr).

[0005] When the host vehicle is traveling at a substantially constant speed, the time to collision can be predicted relatively easily, making it possible to effectively avoid a collision between the host vehicle and a moving object.

[0006] However, when the vehicle is accelerating from a low vehicle speed or a stopped state to enter an intersection, it may be difficult to avoid a head-on collision using FCTB control.

[0007] In other words, when the vehicle is accelerating, the time (position) of the predicted collision changes constantly, which can lead to delays in issuing a warning to the driver or activating the automatic brakes, causing the driver and passengers to panic.

[0008] To provide a vehicle driving support device that can effectively avoid a head-on collision without panicking the driver or passengers, even if a moving target is detected when the vehicle is started and accelerated from a low vehicle speed or a stopped state and is about to enter an intersection or the like.

[0009] One aspect of the present invention is a driving assistance device for a vehicle that includes a starting acceleration detection unit that detects a vehicle speed and acceleration when the host vehicle starts, a target information detection unit that detects moving targets around the host vehicle and a relative distance between the moving targets and the host vehicle, a brake drive unit that forcibly drives the brakes, and a driving control unit that, when the moving target is detected by the target information detection unit, activates the brake drive unit to forcibly intervene in the brakes if a collision is predicted based on a relative position between the host vehicle and the moving target, the driving control unit has a starting scenario determination unit and a control intervention determination unit, and the starting scenario determination unit determines whether the host vehicle will start accelerating based on the vehicle speed and the acceleration detected by the starting acceleration detection unit. a control object recognition processing unit that, when it is determined that the moving target detected by the target information detection unit is approaching the host vehicle from the side, recognizes the moving target as a control object; and a relative information acquisition processing unit that, based on the relative distance between the control object recognized by the control object recognition processing unit and the host vehicle, checks whether the control object has entered an intrusion area set on the side of the host vehicle, and when the control intervention determination unit determines that the host vehicle is accelerating from a start and the relative information acquisition processing unit determines that the control object has entered the intrusion area, the control intervention determination unit forcibly drives the brake via the brake drive unit.

[0010] 1 is a schematic configuration diagram of a driving assistance device. FIG. 1 is a flowchart showing a departure scenario determination routine. FIG. 2 is a flowchart showing a departure acceleration determination processing subroutine. FIG. 3 is a flowchart showing a control object recognition processing subroutine. FIG. 4 is a flowchart showing a relative information acquisition processing subroutine. FIG. 5 is a flowchart showing an intervention condition setting routine. FIG. 6 is a flowchart showing a control intervention determination routine. FIG. 7 is an explanatory diagram showing a state in which a control object approaches from the right side of the host vehicle when the host vehicle accelerates from departure and enters an intersection. FIG. 8 is an explanatory diagram showing a state in which a control object approaches from the left side of the host vehicle when the host vehicle accelerates from departure and enters an intersection. FIG. 9 is an explanatory diagram showing a state in which a control object approaches the host vehicle within a travel determination angle range.

[0011] An embodiment of the present invention will be described below with reference to the drawings. Note that the drawings are schematic, and the dimensional relationships and ratios of the various parts may differ between the drawings.

[0012] 1, the driving assistance device mounted on the host vehicle M has a cruise control unit 1. Left and right front corner radars (FCRs) 11L, 11R serving as target information detectors are connected to the input side of this cruise control unit 1. The front corner radars 11L, 11R are disposed at the left and right corners of the front part of the body of the host vehicle M, respectively.

[0013] As shown in Figures 8 and 9, each front corner radar 11L, 11R is, for example, a millimeter-wave radar. Each front corner radar 11L, 11R emits radar waves (radio waves, laser beams, etc.) in the horizontal direction at a preset frame period, radially starting from a corner of the front of the vehicle body. The area into which these waves are emitted becomes the detection areas DAl, DAr. Each front corner radar 11L, 11R then receives reflected waves of the emitted radar waves.

[0014] As a result, each of the front corner radars 11L, 11R detects a plurality of reflection points on targets present within the detection areas DAl, DAr. Then, each of the front corner radars 11L, 11R analyzes and groups the positions (relative positions with respect to the vehicle M) and relative speeds of the detected reflection points, thereby recognizing targets such as pedestrians, vehicles, motorcycles, and bicycles that have entered the detection areas DAl, DAr.

[0015] Then, each of the front corner radars 11L, 11R transmits the acquired target information to the cruise control unit 1. Note that each of the front corner radars 11L, 11R is not limited to a millimeter wave radar, and may be a laser radar, a microwave radar, a LIDAR (Light Detection and Ranging) radar, or the like.

[0016] Furthermore, the input side of the cruise control unit 1 is connected to a vehicle speed sensor 12, a straight-ahead running detection sensor 13 as a straight-ahead running detection section, a brake switch 14, and an accelerator sensor 15. The vehicle speed sensor 12 detects the vehicle speed (host vehicle speed) Vm of the host vehicle M. This vehicle speed sensor 12 is composed of, for example, wheel speed sensors provided on each of the four wheels.

[0017] The vehicle speed sensor 12 calculates the vehicle speed Vm from the average value of the wheel speeds detected by each wheel speed sensor. Furthermore, the vehicle speed sensor 12 obtains the longitudinal acceleration by time-differentiating the vehicle speed Vm. Therefore, the vehicle speed sensor 12 functions as a departure acceleration detection unit of the present invention. Note that this acceleration may also be detected by an acceleration sensor. In this case, the vehicle speed sensor 12 and the acceleration sensor correspond to the departure acceleration detection unit of the present invention.

[0018] The straight running detection sensor 13 detects whether the host vehicle M is running straight. The straight running detection sensor 13 is configured with at least one of a steering angle sensor and a yaw rate sensor, for example.

[0019] The brake switch 14 detects the depression of a brake pedal (not shown) by the driver. When the driver depresses the brake pedal, the brake switch 14 transmits an ON signal to the cruise control unit 1. The accelerator sensor 15 transmits an accelerator opening signal, which indicates the amount of depression of the accelerator pedal by the driver, to the cruise control unit 1.

[0020] A pseudo accelerator opening signal is also input to the cruise control unit 1. This pseudo accelerator opening signal is output from an ACC (Adaptive Cruise Control) control unit (not shown). This pseudo accelerator opening signal is sent to converge the host vehicle speed Vm [Km / h] to a target vehicle speed set by the ACC control unit.

[0021] Also, a driving force control unit (driving force_ECU) 21, a brake control unit (brake_ECU) 22, and an alarm device 23 are connected to the output side of the driving control unit 1. The driving force_ECU 21 controls the driving force of a driving source 24. The driving source 24 is, for example, at least one of an engine and an electric motor.

[0022] The brake_ECU 22 drives the brake actuator 25. The brake actuator 25 adjusts the brake fluid pressure supplied to the wheel cylinder of the brake caliper provided on each wheel. When the brake actuator 25 is driven by a signal from the brake_ECU 22, the wheel cylinder provided on each wheel operates to forcibly decelerate the host vehicle M. The brake_ECU 22 and the brake actuator 25 constitute a brake drive unit of the present invention.

[0023] The warning device 23 is composed of a monitor and an audio device. When the cruise control unit 1 attempts to forcibly decelerate the host vehicle M, it activates the warning device 23 to alert the driver with visual and audio signals.

[0024] The driving control unit 1 and each ECU 21, 22 are configured with a microcontroller including a CPU, RAM, ROM, rewritable non-volatile memory (flash memory or EEPROM), and peripheral devices. The ROM stores programs and fixed data necessary for the CPU to execute various processes. The RAM serves as a work area for the CPU, temporarily storing various data for the CPU. The CPU is also called an MPU (microprocessor) or processor. A GPU (graphics processing unit) or GSP (graph streaming processor) may be used instead of the CPU. Alternatively, a CPU, GPU, and GSP may be selectively combined.

[0025] Meanwhile, the cruise control unit 1 includes a departure scenario determination unit 1a, an intervention condition setting unit 1b, and a control intervention determination unit 1c as functions for performing front cross traffic braking (FCTB) control. Hereinafter, the term "FCTB control" will also include FCTAB (Front Cross Traffic Alert Braking). The FCTB control is a function for preventing head-on collisions at intersections and the like. The FCTB control aims to avoid collisions with targets (vehicles, motorcycles, bicycles, etc.) approaching the host vehicle M from a crossing direction. <Departure scenario determination unit 1a>

[0026] The starting scenario determination unit 1a determines whether a starting scenario for when FCTB control intervenes is established (ON). This starting scenario is a preset condition for determining whether the timing for intervening FCTB control should be advanced.

[0027] The determination process in the departure scenario determination unit 1a is specifically executed in accordance with a departure scenario determination routine shown in Fig. 2. This routine is executed at predetermined calculation intervals after the system is started.

[0028] The departure scenario determination unit 1a first performs a departure acceleration determination process to check whether the host vehicle M has accelerated from a start (step S1). Next, the departure scenario determination unit 1a performs a control object recognition process to check whether a control object C approaching the host vehicle M has been recognized (step S2). Next, the departure scenario determination unit 1a executes a relative information acquisition process to acquire relative information between the host vehicle M and the control object C (step S3).

[0029] The start acceleration determination process in step S1 is executed in accordance with a start acceleration determination process subroutine shown in Fig. 3. The process in this subroutine corresponds to the start acceleration determination processing section of the present invention.

[0030] In this subroutine, the departure scenario determination unit 1a first checks whether the host vehicle M is accelerating (step S11). Whether the host vehicle M is accelerating is determined based on the acceleration of the host vehicle M detected by the vehicle speed sensor 12.

[0031] If the departure scenario determination unit 1a determines that the host vehicle M is accelerating (YES), it proceeds to step S12. If the departure scenario determination unit 1a determines that the host vehicle M is not accelerating (NO), it jumps to step S17.

[0032] When the start scenario determination unit 1a proceeds to step S12, it checks whether the host vehicle M is starting from an extremely low speed or less. The host vehicle speed Vm is detected by the vehicle speed sensor 12. An extremely low speed is a speed at which the host vehicle M can be stopped immediately. This extremely low speed is, for example, approximately 5 to 10 km / h. Therefore, starting the host vehicle M from a stopped state is also included in starting from an extremely low speed or less.

[0033] If the departure scenario determination unit 1a determines that the vehicle is starting from an extremely low speed or slower (step S12: YES), the process proceeds to step S13. If the departure scenario determination unit 1a determines that the current acceleration is not a departure from an extremely low speed or slower (step S12: NO), the process jumps to step S17.

[0034] When the process proceeds to step S13, the start scenario determination unit 1a checks whether the accelerator pedal is being depressed within a certain range. The accelerator pedal depression is determined based on the accelerator pedal position signal. The cruise control unit 1 receives the accelerator pedal position signal detected by the accelerator sensor 15 and a pseudo accelerator pedal position signal from an ACC control unit (not shown).

[0035] If the departure scenario determination unit 1a determines that the accelerator pedal is depressed within a certain range (YES), it proceeds to step S14. On the other hand, if the departure scenario determination unit 1a determines that the accelerator pedal is not depressed (NO), it jumps to step S17.

[0036] For example, if the driver depresses the brake pedal before an intersection to temporarily stop, and then releases the brake pedal, the host vehicle M will start moving due to creep. Also, in ACC control, if the driver depresses the brake pedal after the host vehicle M has automatically stopped, the ACC control is automatically released. If the driver releases the brake pedal after the ACC control is automatically released, the host vehicle M will start moving due to creep. If the host vehicle M starts moving in such a situation, the start scenario determination unit 1a determines that the accelerator pedal is not depressed (NO).

[0037] Step S13 checks whether the driver or the ACC control unit is actively accelerating the host vehicle M. If the accelerator pedal is depressed, the driver or the ACC control is actively accelerating the host vehicle M to enter the intersection. In such an accelerated situation immediately after starting, the collision position with a moving object approaching the host vehicle M from the lane intersecting the host vehicle M's lane changes from moment to moment.

[0038] Therefore, it is difficult to predict the collision position between the host vehicle M and the moving object. As a result, even if the cruise control unit 1 detects a moving object and executes automatic brake control by normal FCTB control, a delay is likely to occur.

[0039] Then, in step S14, the departure scenario determination unit 1a checks whether the host vehicle speed detected by the vehicle speed sensor 12 is equal to or lower than a predetermined upper limit. This upper limit is, for example, approximately 10 to 15 km / h. Step S14 checks the state of the host vehicle M immediately after it accelerates from an extremely low speed.

[0040] If the departure scenario determination unit 1a determines that the vehicle speed is equal to or lower than the predetermined upper limit (step S14: YES), it proceeds to step S15. On the other hand, if the departure scenario determination unit 1a determines that the vehicle speed exceeds the predetermined upper limit (step S14: NO), it jumps to step S17.

[0041] In step S15, the departure scenario determination unit 1a checks whether the host vehicle M is traveling straight, in other words, whether the host vehicle M is exhibiting a turning behavior. If the driver or the ACC control is operating the steering wheel at an intersection to turn the vehicle M, it is difficult for the departure scenario determination unit 1a to predict the collision position.

[0042] Whether the host vehicle M is traveling straight or not is determined based on parameters detected by the straight traveling detection sensor 13. The straight traveling detection sensor 13 makes the determination based on values ​​detected by at least one of a steering angle sensor and a yaw rate sensor.

[0043] The departure scenario determination unit 1a determines that the vehicle is traveling straight ahead when the steering angle detected by the steering angle sensor is at a neutral position within a certain angle range. The departure scenario determination unit 1a also determines that the vehicle is traveling straight ahead when the yaw rate detected by the yaw rate sensor is within a predetermined value. Alternatively, the departure scenario determination unit 1a determines that the vehicle is traveling straight ahead when the steering angle detected by the steering angle sensor is at a neutral position within a certain angle range, the yaw rate detected by the yaw rate sensor is within a predetermined value, and the steering angle velocity, which is the amount of change per unit time of the steering angle detected by the steering angle sensor, is within a certain range.

[0044] If the departure scenario determination unit 1a determines that the host vehicle M is traveling straight ahead (step S15: YES), it proceeds to step S16. On the other hand, if the departure scenario determination unit 1a determines that the host vehicle M is not traveling straight ahead (step S15: NO), it branches to step S17.

[0045] In step S16, the departure scenario determination unit 1a determines that the host vehicle M is accelerating for departure while traveling straight ahead, and sets the departure acceleration flag Facc (Facc←1). In step S17, the departure scenario determination unit 1a clears the departure acceleration flag Facc (Facc←0). The departure scenario determination unit 1a then executes the process in step S2 of FIG. 2.

[0046] The control object recognition process in step S2 in Fig. 2 is executed in accordance with a control object recognition process subroutine shown in Fig. 4. The process in this subroutine corresponds to the control object recognition processing unit of the present invention.

[0047] In this subroutine, the departure scenario determination unit 1a first checks the value of the departure acceleration flag Facc (step S21). If Facc = 1 (YES), the departure scenario determination unit 1a proceeds to step S22. If Facc = 0 (NO), the departure scenario determination unit 1a jumps to step S28.

[0048] In step S22, the departure scenario determination unit 1a checks whether a moving target has been detected to the side of the host vehicle M. Whether or not this moving target has been detected is determined based on signals from the left and right front corner radars 11L, 11R. If the departure scenario determination unit 1a detects an object entering the radial detection areas DAl, DAr (YES), the departure scenario determination unit 1a proceeds to step S23. If the departure scenario determination unit 1a does not detect an object in the detection areas DAl, DAr (NO), the departure scenario determination unit 1a jumps to step S28.

[0049] When the process proceeds to step S23, the departure scenario determination unit 1a checks whether the moving target is moving in the direction of the host vehicle M. Whether the moving target is moving in the direction of the host vehicle M is determined based on the change in the relative distance Dx between the moving target and the host vehicle M, based on signals from the left and right front corner radars 11L, 11R.

[0050] Then, if the relative distance Dx between the moving target and the host vehicle M is gradually becoming shorter, the departure scenario determination unit 1a determines that the moving target is moving in the direction of the host vehicle M (step S23: YES) and proceeds to step S24. Also, if the relative distance Dx between the moving target and the host vehicle M is gradually becoming longer or is not changing, the departure scenario determination unit 1a determines that the moving target is not moving in the direction of the host vehicle M (step S23: NO) and branches to step S28.

[0051] In step S24, the departure scenario determination unit 1a detects the moving speed Sm of the moving target. The departure scenario determination unit 1a obtains the relative speed (longitudinal and lateral speeds relative to the host vehicle M) from the speed vector in the moving direction of the moving target recognized by the left and right front corner radars 11L and 11R. Then, based on this relative speed data and the host vehicle speed Vm (longitudinal and lateral speeds of the host vehicle M), the departure scenario determination unit 1a calculates the moving speed Sm of the moving target (longitudinal and lateral speeds relative to the host vehicle M).

[0052] Next, the departure scenario determination unit 1a checks whether the moving speed Sm of the moving target is within a predetermined range (step S25). This speed range may have an upper limit of approximately 50 to 65 [Km / h] and a lower limit of approximately 5 to 10 [Km / h]. If the departure scenario determination unit 1a determines that the moving speed Sm is within the predetermined speed range (YES), the process proceeds to step S26. On the other hand, if the departure scenario determination unit 1a determines that the moving speed Sm is outside the predetermined speed range (NO), the process branches to step S28.

[0053] Then, in step S26, the departure scenario determination unit 1a recognizes the moving object as a control target C (see Figures 8 and 9) approaching the host vehicle M. Note that although Figures 8 and 9 show a vehicle as the control target C, this control target C also includes motorcycles and bicycles.

[0054] Next, the departure scenario determination unit 1a sets the control object recognition flag Fc (step S27: Fc←1) and proceeds to step S3 in Fig. 2. Also, when proceeding to step S28 from any of steps S22, S23, and S25, the departure scenario determination unit 1a clears the control object recognition flag Fc (Fc←0) and proceeds to step S3 in Fig. 2.

[0055] The relative information acquisition process in step S3 in Fig. 2 is executed in accordance with a relative information acquisition process subroutine shown in Fig. 5. The process in this subroutine corresponds to the relative information acquisition processing unit of the present invention.

[0056] The departure scenario determination unit 1a first checks the values ​​of the departure acceleration flag Facc and the control object recognition flag Fc (step S31). If the departure scenario determination unit 1a determines that both flags Facc and Fc are set (Facc, Fc = 1), the process proceeds to step S32. If the departure scenario determination unit 1a determines that either flag Facc or Fc is cleared (Facc, Fc = 0, or Facc = 0, or Fc = 0), the process jumps to step S36.

[0057] In step S32, the departure scenario determination unit 1a checks whether the control object C detected based on the signals from the left and right front corner radars 11L, 11R has entered the left and right intrusion areas AR1, ARr set in front of the host vehicle M. These intrusion areas AR1, ARr are areas in which the control object C detected by the front corner radars 11L, 11R is in a state where it is difficult to avoid a collision with the control object C detected by the front corner radars 11L, 11R under normal driving conditions because an alarm or automatic braking cannot be issued in time.

[0058] 8 and 9, within the detection areas DAl, DAr of the left and right front corner radars 11L, 11R, each intrusion area ARl, ARr is set in a horizontally long rectangular shape in front of the host vehicle M. As shown in Fig. 8, the right intrusion area ARr is set as an area extending slightly from the detection area DAr on the right front corner radar 11R side of the host vehicle M into the detection area DAl of the left front corner radar 11l. Also, as shown in Fig. 9, the left intrusion area ARl is set as an area extending slightly from the detection area DAl of the left front corner radar 11L of the host vehicle M into the detection area DAl of the right front corner radar 11l.

[0059] If the departure scenario determination unit 1a determines that the control target C has entered the left or right intrusion area ARl or ARr (step S32: YES), the process proceeds to step S33. If the departure scenario determination unit 1a determines that the control target C has not entered the left or right intrusion area ARl or ARr (step S32: NO), the process branches to step S36.

[0060] In step S33, the departure scenario determination unit 1a detects the travel angle range θp of the control object C. As shown in Figures 8 and 9, this travel angle range θp is the angle between the travel directions of the host vehicle M traveling straight ahead and the control object C. The travel direction of the control object is set, for example, based on the speed vector obtained when estimating the movement speed Sm in step S24 of the control object recognition processing subroutine shown in Figure 4.

[0061] Next, the departure scenario determination unit 1a compares the travel angle θp with a preset travel angle range (θmax-θmin) (step S34). This travel angle range (θmax-θmin) is a range in which the control target C may collide with the host vehicle M. As shown in FIG. 10, this travel determination angle range is set by a maximum travel angle θmax and a minimum travel angle θmin.

[0062] If the departure scenario determination unit 1a determines that the control object C is approaching the host vehicle M within the travel angle range (θmin≦θp≦θmax) (YES), the process proceeds to step S35. If the departure scenario determination unit 1a determines that the control object C is approaching the host vehicle M within the travel angle range (θp>θmin or θmax<θp) (NO), the process branches to step S36.

[0063] When the process proceeds to step S35, the departure scenario determination unit 1a sets the departure scenario to ON, and the process proceeds to step S4 in Fig. 2. Also, when the process branches to step S36 from any of steps S31, S32, and S34, the departure scenario determination unit 1a sets the departure scenario to OFF, and the process proceeds to step S4 in Fig. 2.

[0064] 2, the departure scenario determination unit 1a checks whether the departure scenario is ON. If the departure scenario is ON, the departure scenario determination unit 1a proceeds to step S5, sets the departure scenario flag Fs (Fs←1), and exits the routine. If the departure scenario is OFF, the departure scenario determination unit 1a branches to step S6, clears the departure scenario flag Fs (Fs←0), and exits the routine.

[0065] <Intervention Condition Setting Unit 1b> Next, the processing in the intervention condition setting unit 1b will be described. The processing in the intervention condition setting unit 1b is executed according to an intervention condition setting routine shown in FIG.

[0066] In this subroutine, the intervention condition setting unit 1b first refers to the value of the departure scenario flag Fs (step S41). If the intervention condition setting unit 1b determines that the departure scenario flag Fs is cleared (NO), the routine is terminated. As a result, normal FCTB control is executed.

[0067] On the other hand, if the intervention condition setting unit 1b determines that the departure scenario flag Fs is set (YES), the process proceeds to step S42. In step S42, the intervention condition setting unit 1b replaces the relative distance determination threshold Dxth set in normal FCTB control with the relative distance determination threshold Ds for the departure scenario, and then exits the routine. This relative distance determination threshold Ds for the departure scenario is set to a distance longer than the relative distance determination threshold Dxth set in normal FCTB control.

[0068] That is, when the host vehicle M is accelerating after starting, the host vehicle speed Vm is predicted to increase in the future. On the other hand, when the host vehicle M is traveling at a low speed without accelerating, the possibility of collision with the control target C is low, and it is considered that there is no need to apply the brakes immediately.

[0069] On the other hand, if the host vehicle M accelerates, the host vehicle speed Vm will become high in the future, and the host vehicle M will enter an intersection or the like at this high speed. If the host vehicle M enters an intersection or the like at high speed, it will be difficult to avoid a head-on collision with the control object C even if the brakes are forcibly applied. Therefore, in this embodiment, the brakes are forcibly applied early before the host vehicle speed Vm becomes high, thereby avoiding a collision with the control object C.

[0070] The relative distance determination threshold Dxth set in normal FCTB control is an intervention distance calculated based on the current host vehicle speed Vm (e.g., low speed), so it is relatively easy to avoid a collision even if it is set to a relatively short distance. In contrast, when the host vehicle speed M is in a start-accelerating state, it is necessary to predict the future speed to avoid a collision with the control target C. The relative distance determination threshold Ds for the start-accelerating scenario is set based on the intervention distance calculated based on the future speed at which the host vehicle M will be in a start-accelerating state. Therefore, the relative distance determination threshold Ds for the start-accelerating scenario is set to a distance longer than the relative distance determination threshold Dxth. This relative distance determination threshold Ds for the start-accelerating scenario is set to a range in which control intervention is performed in a range in which delays in warnings and brake control occur in normal FCTB control. While the normal relative distance determination threshold Dxth is approximately 5 to 10 km / h, the relative distance determination threshold Ds for the start-accelerating scenario is set to, for example, approximately 10 to 15 m.

[0071] <Control Intervention Determining Unit 1c> Next, the processing in the control intervention determining unit 1c will be described. The processing in the control intervention determining unit 1c is executed according to a control intervention determination routine shown in FIG.

[0072] The control intervention determination unit 1c first refers to the value of the start scenario flag Fs (step S51). If the control intervention determination unit 1c determines that the start scenario flag Fs is cleared (NO), the control intervention determination unit 1c exits the routine.

[0073] If the control intervention determination unit 1c determines that the start scenario flag Fs is set (YES), the process proceeds to step S52. In step S52, the control intervention determination unit 1c reads the relative distance Dx between the host vehicle M and the control target C.

[0074] The control intervention determination unit 1c then compares the relative distance Dx with the relative distance determination threshold Dxth (step S53). The value of this relative distance determination threshold Dxth has been rewritten by the intervention condition setting unit 1b as the relative distance determination threshold Ds for the starting scenario.

[0075] If the control intervention determination unit 1c determines that Dx≦Dxth (YES), the process proceeds to step S54. If the control intervention determination unit 1c determines that Dx>Dxth (NO), the process exits the routine.

[0076] In step S54, the control intervention determination unit 1c outputs a power-off signal to the driving force_ECU 21. The driving force_ECU 21 then stops the driving source 24. As a result, the host vehicle M will not accelerate even if the driver depresses the accelerator pedal.

[0077] Thereafter, the control intervention determination unit 1c transmits a warning signal to the warning device 23 (step S55). The warning device 23 then notifies the occupants, including the driver, by audio and video that the control target C is approaching from the side.

[0078] Next, the control intervention determination unit 1c transmits an Autonomous Emergency Stop Braking signal to the brake_ECU 22 (step S56). The brake_ECU 22 then sets the brake fluid pressure to a value higher than that set during normal FCTB control, and outputs the set value to the brake actuator 25 to forcibly decelerate the host vehicle M.

[0079] Then, the control intervention determination unit 1c checks whether the host vehicle M has stopped (step S57). Whether the host vehicle M has stopped is determined based on the host vehicle speed Vm detected by the vehicle speed sensor 12. If the control intervention determination unit 1c determines that the host vehicle speed Vm indicates that the host vehicle M has not yet stopped (Vm>0), the process returns to step S54 and executes the processes of steps S54 to S57. On the other hand, if the control intervention determination unit 1c determines that the host vehicle M has stopped (Vm=0), the process proceeds to step S58.

[0080] Therefore, after activating the emergency stop brake, the control intervention determination unit 1c continues the emergency stop brake even if the start scenario is set to OFF in the start scenario determination routine shown in Figure 2.

[0081] Then, when the process proceeds to step S58, the control intervention determination unit 1c sends an alarm release signal to the alarm device 23 and exits the routine. The alarm device 23 then stops the alarm. Meanwhile, the brake actuator 25 continues to apply the brakes. This brake application state is released when the cruise control unit 1 detects a release operation by the driver. The driver's release operation is, for example, when the brake switch 14 is turned on by depressing the brake pedal.

[0082] In conventional FCTB control, when a control target C approaches the vehicle M from the side, the collision prediction time is calculated, and if this collision prediction time falls below a preset threshold value, emergency braking is activated.

[0083] However, while the host vehicle M is accelerating from a standstill, the predicted collision time constantly changes. Therefore, in conventional FCTB control, a delay in the timing of applying the emergency brake is likely to occur. In contrast, in this embodiment, if it is determined that the relative distance Dx is equal to or less than the predetermined threshold Dxth (step S53: YES), the emergency stop brake is immediately applied with high brake fluid pressure (step S56) to bring the host vehicle M to a stop (step S57). Therefore, even if a control target C is detected when the host vehicle M is accelerating from a low vehicle speed or a stopped state and entering an intersection, a head-on collision can be effectively avoided without panicking the driver or passengers.

[0084] In this embodiment, conditions for determining the start scenario are set for the host vehicle M and the control object C, and the start scenario is turned ON when all of these conditions are satisfied. This makes it possible to accurately recognize the start acceleration state of the host vehicle M and the control object C approaching the host vehicle M. As a result, it is possible to effectively prevent the host vehicle M from being brought to an unintentional emergency stop during start acceleration or normal driving.

[0085] The present invention is not limited to the above-described embodiment, and other elements may be added as the determination conditions for the start acceleration determination process and the recognition processing conditions for the control object recognition process, for example.

Claims

1. A driving assistance device for a vehicle comprising: a departure acceleration detection unit that detects the vehicle speed and acceleration when the host vehicle starts; a target information detection unit that detects moving targets around the host vehicle and the relative distance between the moving targets and the host vehicle; a brake drive unit that forcibly drives the brakes; and a driving control unit that, when the target information detection unit detects the moving target and predicts a collision based on the relative position of the host vehicle and the moving target, activates the brake drive unit to forcibly intervene in the brakes, wherein the driving control unit has a departure scenario determination unit and a control intervention determination unit, wherein the departure scenario determination unit has: a departure acceleration determination processing unit that checks whether the host vehicle is accelerating for departure based on the vehicle speed and the acceleration detected by the departure acceleration detection unit; and a control target recognition processing unit that recognizes the moving target detected by the target information detection unit as a control target when it is determined that the moving target is approaching the host vehicle from the side. a relative information acquisition processing unit that checks whether the control target has entered an intrusion area set on the side of the host vehicle based on the relative distance between the control target recognized by the control target recognition processing unit and the host vehicle, wherein the control intervention determination unit forcibly drives the brake via the brake drive unit when the start acceleration determination processing unit determines that the host vehicle is accelerating from a start and the relative information acquisition processing unit determines that the control target has entered the intrusion area.

2. The vehicle driving assistance device according to claim 1, characterized in that the departure acceleration determination processing unit determines that the vehicle is accelerating from an extremely low speed based on the vehicle speed and acceleration detected by the departure acceleration detection unit.

3. A driving assistance device for a vehicle as described in claim 1, further comprising a straight-line running detection unit that detects straight-line running of the vehicle, wherein the departure acceleration determination processing unit determines that the vehicle is accelerating from a very low speed when the vehicle speed detected by the departure acceleration detection unit is equal to or lower than a preset upper limit vehicle speed and the vehicle is accelerating from a very low speed and the straight-line running detection unit has detected straight-line running.

4. The vehicle driving assistance device according to claim 1, characterized in that the target information detection unit detects moving targets around the host vehicle, the relative distance between the moving targets and the host vehicle, and the moving speed of the moving targets, and the target recognition processing unit to be controlled determines that the moving target detected by the target information detection unit is approaching the host vehicle from the side and, if the moving speed is equal to or less than a preset threshold, recognizes the moving target as a target to be controlled.

5. The vehicle driving assistance device according to claim 1, characterized in that the relative information acquisition processing unit checks whether the control object has entered an intrusion area set on the side of the host vehicle and whether the intrusion is at a predetermined traveling angle relative to the host vehicle based on the relative distance between the control object recognized by the control object recognition processing unit and the host vehicle, and the control intervention determination unit forcibly applies the brakes via the brake drive unit when the departure acceleration determination processing unit determines that the host vehicle is accelerating from departure and the relative information acquisition processing unit determines that the control object has entered the intrusion area and is intruding within a predetermined traveling angle range relative to the host vehicle.

6. The vehicle driving assistance device according to claim 1, wherein the control intervention determination unit sets the hydraulic pressure when forcibly applying the brakes to a value higher than normal.

7. A driving assistance device for a vehicle as described in any one of claims 1 to 6, characterized in that the driving control unit further has an intervention condition setting section, wherein the intervention condition setting section sets a relative distance judgment threshold to a distance longer than normal when the departure acceleration judgment processing section determines that the host vehicle is accelerating from departure and the relative information acquisition processing section determines that the control target object has entered the intrusion area, and the control intervention judgment section forcibly activates the brake via the brake drive section when the relative distance becomes shorter than the relative distance judgment threshold.

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