JP2005081999A - Vehicular driving assistance device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular driving assistance device capable of performing adequate traveling to meet a curve even when a proceeding vehicle is lost during following the proceeding vehicle, and the subject vehicle advances in the curve after the elapse of the hold time. <P>SOLUTION: When the duration for the lost status of a proceeding vehicle elapses the hold time, presence/absence of a curve is determined based on information from a steering angle sensor (S109). If it is determined that there is no curve, the target vehicle speed is the set vehicle speed, and acceleration is immediately started (S103). If it is determined that a curve is present, an adequate target vehicle speed according to the radius of curvature of the curve based on the steering angle is calculated. Even if the proceeding vehicle is lost during following the proceeding vehicle, and advances into a curve after the elapse of the hold time, an adequate traveling according to the curve can be performed. Occurrence of the traveling condition against the intention of a driver can be avoided, and sense of incompatibility of the driver can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle driving support device that recognizes an environment outside a vehicle in front of the vehicle and captures a preceding vehicle on a traveling lane based on the recognized environment outside the vehicle.

  In recent years, a vehicle driving support device that recognizes the environment outside the vehicle using a millimeter-wave radar, an infrared laser radar, a stereo camera, a monocular camera, etc., and performs driving control of the own vehicle based on the recognized environment outside the vehicle has been practically used. It is becoming. This type of vehicle driving support device mainly has an inter-vehicle distance control cruise control (ACC) function that performs constant speed traveling control and follow-up traveling control for the preceding vehicle according to the recognition result of the preceding vehicle. It has become.

  During execution of such an ACC function, the vehicle driving support device performs follow-up driving control for the preceding vehicle captured when the preceding vehicle is captured on the own vehicle traveling lane, while the preceding vehicle leaves the own vehicle traveling lane. If it determines with having performed, the control will transfer to constant speed travel control.

  By the way, in this type of vehicle driving support device, there is a case where the preceding vehicle temporarily disappears (lost) for some reason as a state in which the preceding vehicle cannot be captured on the own vehicle traveling lane. When such a preceding vehicle is lost, the ACC control normally determines that the preceding vehicle has left with a predetermined holding time after the preceding vehicle has become uncaptured. Until the time elapses, the traveling state during the follow-up traveling control is maintained, and when the retention time elapses, acceleration is started to quickly return to constant speed traveling.

For example, Patent Document 1 discloses a technique in which when a preceding vehicle cannot be captured during follow-up traveling control, the vehicle travels while maintaining the current vehicle speed for a predetermined time (for example, 2 seconds), and then shifts to constant speed traveling control. Is disclosed.
JP 7-89366 A

  However, when the preceding vehicle is lost due to curve driving, that is, as shown in FIG. 6A, the host vehicle C1 is traveling in a state of following the preceding vehicle C2, and the preceding vehicle C2 is in a curve. If it is determined that the vehicle has entered and is out of the capture range of the vehicle C1 and is lost, the speed immediately before the lost is held until the holding time elapses. However, as shown in FIG. If the vehicle C1 does not reach the curve, the vehicle automatically switches from the follow-up running control to the constant speed running control and enters the curve. For this reason, there is a possibility that the vehicle may be accelerated by a curve against the will of the driver, approaching the preceding vehicle, or causing the driver to feel uncomfortable.

  The present invention has been made in view of the above circumstances, and even when the preceding vehicle is lost while following the preceding vehicle and enters the curve after the holding time has elapsed, an appropriate traveling according to the curve is performed. It is an object of the present invention to provide a vehicle driving support device that can make the above possible.

  In order to achieve the above object, the vehicle driving support apparatus of the present invention is configured to capture a preceding vehicle on the traveling lane of the own vehicle based on the recognition result of the outside environment, and while following the captured preceding vehicle. When the preceding vehicle is lost, a means for detecting the presence or absence of a curve on the road, and when a set time elapses after the preceding vehicle is lost and the curve is detected, the target vehicle speed of the own vehicle is And a means for correcting acceleration / deceleration according to the radius of curvature.

  The vehicle driving support device according to the present invention enables the vehicle to travel appropriately according to the curve even when the preceding vehicle is lost during the follow-up traveling to the preceding vehicle and enters the curve after the holding time has elapsed. Therefore, it is possible to prevent the driver from feeling uncomfortable by avoiding the occurrence of a running state contrary to the driver's intention.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 relate to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram of a vehicle equipped with a driving support device, FIG. 2 is an overall system configuration diagram of the vehicle driving support device, and FIG. 3 is cruise control. FIG. 4 is a functional block diagram, FIG. 4 is a flowchart of a target vehicle speed calculation routine, and FIG. 5 is an explanatory diagram showing changes in the target vehicle speed after the preceding vehicle is lost.

  In FIG. 1, reference numeral 1 denotes a vehicle such as an automobile (own vehicle), and a driving assistance device (ADA: Active Drive Assist system) 2 is mounted on the vehicle 1. As shown in FIG. 2, the driving support apparatus 2 includes a stereo camera unit 3, a millimeter wave radar unit 4, an image processing unit (IPU) 5, a preview control unit (PCU) 6, and an engine control unit (ECU). 7, a vehicle dynamics control unit (VDC) 8, and an integrated unit 9, which are connected by a multiple communication system such as a CAN (Controller Area Network). Moreover, the center display 10, the combination meter 11, and the audio apparatus 12 are connected to the integrated unit 9 via other communication systems (vehicle body side communication systems) having different communication speeds, for example.

  The stereo camera unit 3 includes a pair of (left and right) CCD cameras using a solid-state imaging device such as a charge coupled device (CCD). These left and right CCD cameras are each mounted at a predetermined interval in front of the ceiling in the vehicle interior (see FIG. 1), and images the object outside the vehicle from different viewpoints. The stereo camera unit 3 performs A / D conversion, affine conversion, and the like on each image (reference image and comparison image) captured by the left and right CCD cameras, and outputs these image signals to the IPU 5.

  The millimeter wave radar unit 4 is attached to, for example, a front bumper structure material of the vehicle 1 (see FIG. 1). The millimeter wave radar unit 4 has a transmission / reception unit (not shown), and the transmission / reception unit transmits and receives millimeter waves in the horizontal direction of the vehicle 1 within a predetermined scanning range at regular intervals. Then, the millimeter wave radar unit 4 generates a radar image composed of two-dimensional distribution information of the three-dimensional object ahead of the host vehicle based on the time difference until the transmitted millimeter wave is reflected by the reflection object such as the three-dimensional object and returns. It is generated and output to the IPU 5.

  Each image signal from the stereo camera unit 3 and the millimeter wave radar unit 4 is processed by the IPU 5, and the recognition result of the vehicle exterior environment is output from the IPU 5.

  More specifically, the IPU 5 uses a well-known calculation process based on the stereo image and the triangulation principle, etc., to obtain a white line on the road, a side wall such as a guardrail or curb along the road, and a three-dimensional vehicle or the like. Recognize things. Then, the IPU 5 assigns a different ID to each data related to the recognized white line, side wall, and three-dimensional object. At that time, since a three-dimensional object such as a vehicle often has two or more faces continuously recognized through a corner, the IPU 5 converts a three-dimensional object such as a vehicle into a corner-shaped three-dimensional object. Register separately.

  Further, the IPU 5 performs a three-dimensional object recognition based on the radar image by extracting a portion where distance values on the radar image are continuous as one solid object. Then, the IPU 5 assigns an ID to each data related to the recognized three-dimensional object.

  Further, the IPU 5 combines the three-dimensional object recognized on the basis of the stereo image (hereinafter referred to as an image three-dimensional object) and the three-dimensional object recognized on the basis of the radar image (hereinafter referred to as a radar three-dimensional object). 3D object recognition. That is, the IPU 5 determines the same probability for each combination of each image three-dimensional object and each radar three-dimensional object based on each image three-dimensional object, each radar three-dimensional object, and the position and moving speed, and the same probability exceeds a predetermined value. Each combination of the image solid object and the radar solid object that most closely matches is recognized as a solid object (fusion solid object) by sensor fusion between the stereo image and the millimeter wave radar.

  Thereby, in IPU5, it consists of either the solid thing recognized by the image solid thing simple substance, the solid thing recognized by the radar solid thing simple substance, or the fusion solid thing recognized by the combination of the image solid thing and the radar solid thing. Recognize each three-dimensional object ahead of the vehicle.

  Further, the IPU 5 estimates the own vehicle traveling lane based on the information such as the white line and the side wall recognized from the stereo image, the traveling state information of the own vehicle 1 obtained from the VDC 8, and the estimated own vehicle traveling lane. Capture the preceding car above. Specifically, a three-dimensional object existing on the own vehicle traveling lane is extracted, and when a three-dimensional object is extracted on the own vehicle traveling lane, the three-dimensional object located closest to the own vehicle is selected as the preceding vehicle. To capture as.

  The recognition result of the environment outside the vehicle by the IPU 5 described above is input to the PCU 6 that controls each function of the driving support device 2. The PCU 6 determines whether or not an alarm or acceleration / deceleration control is necessary based on information obtained from the IPU 5 or the VDC 8, and outputs a display signal to the center display 10 or the combination meter 11 according to these determination results. Various driving support functions are realized by appropriately outputting buzzer (or audio) signals to the speakers 11a and 12a connected to the meter 11 and the audio device 12, and outputting control signals to the ECU 7 and the VDC 8, as appropriate.

  As a driving support function by the PCU 6, for example, when a preceding vehicle is captured on the own vehicle traveling lane, the PCU 6 monitors the inter-vehicle distance with the preceding vehicle, and the inter-vehicle distance becomes equal to or less than a predetermined alarm inter-vehicle distance. When this occurs, the warning light of the combination meter 11 is displayed and a buzzer is output from the speaker 11a (inter-vehicle distance warning function).

  Further, the PCU 6 determines that the distance between the white line and the extension line of the outer side wall of the own vehicle 1 is approximately “0” within a preset front distance from the positional relationship between the white line of the own vehicle traveling lane and the own vehicle 1. When it is determined, the warning light of the combination meter 11 is turned on and a buzzer is output from the speaker 11a (lane departure warning function).

  Further, the PCU 6 measures the wobbling on the driving lane based on the relationship between the own vehicle 1 and the white line, and when detecting the wobbling deeply related to looking away or falling asleep from the frequency analysis, Advance timing. Further, when a lane departure is detected, a warning is given by voice from the speaker 12a (stagger warning function).

  Further, the PCU 6 detects the wheel speed difference between the front and rear wheels when the driver depresses the brake. When this value exceeds a predetermined value, the PCU 6 determines that the tire is likely to slip, and this is indicated through the center display 10. Display (grip prediction function).

  Further, the PCU 6 displays information on the distance between the preceding vehicle traveling on the vehicle traveling lane and the oncoming vehicle through the center display 10. Further, when the host vehicle approaches the preceding vehicle at a speed equal to or higher than a certain speed, a buzzer is output from the speaker 12a (visual field support function).

  Furthermore, when the driver sets a desired traveling vehicle speed by operating a touch switch provided on the center display 10 when there is no preceding vehicle on the own vehicle traveling lane, the PCU 6 performs automatic constant speed traveling at the set vehicle speed. When the preceding vehicle that is slower than the host vehicle is captured on the host vehicle lane, follow-up driving control is performed to maintain an appropriate inter-vehicle distance (inter-vehicle distance control cruise control function; ACC (Adaptive Cruise Control) function) ).

  The touch switch of the center display 10 is used for executing / releasing each driving support function, switching the display of the center display 10, and the like. A main switch for turning on / off the ACC function, a target vehicle speed at constant speed running. The ACC function can be selected by operating a vehicle speed switch that sets the vehicle speed, a coast switch that mainly changes and sets the target vehicle speed to the lower side, a resume switch that mainly changes and sets the target vehicle speed to the higher side.

  In addition, this ACC control function is used when the IPU 5 detects a deterioration in the imaging environment such as fog, rain, or backlight based on the stereo image, as well as when the system detects an abnormality in each unit. Implementation is prohibited when lens dirt, radar axis misalignment based on radar images, dirt on the radar cover, or the like is detected.

  FIG. 3 shows the main part of the ACC control function in the PCU 6, which mainly includes a state transition calculation unit 20, a curve calculation unit 21, and a target vehicle speed calculation unit 22, and the target vehicle speed is an instruction value for engine output control by the ECU 7. Is output from the PCU 6 to the ECU 7.

  The state transition calculating unit 20 is a constant speed traveling mode that controls to maintain the set vehicle speed set by the driver when there is no preceding vehicle on the own vehicle traveling lane, and a lower speed preceding the own vehicle on the own vehicle traveling lane. Based on the follow-up running mode that keeps an appropriate inter-vehicle distance from the captured preceding vehicle when the vehicle is captured, the holding travel mode that maintains the vehicle speed at the time of lost when the preceding vehicle is lost during following traveling The acceleration / deceleration mode via the VDC 8 is calculated based on the preceding vehicle information from the IPU 5. The calculation result of this state transition is updated as needed based on the preceding vehicle information from the IPU 5.

  When returning from the holding control mode, the curve calculation unit 21 determines the presence / absence of a curve based on steering angle information from a steering angle sensor (not shown), and calculates the curvature radius of the curve from the steering angle when determining that there is a curve. And output to the target vehicle speed calculation unit 22.

  The target vehicle speed calculation unit 22 calculates the target vehicle speed corresponding to the state transition of each mode from the state transition calculation unit 20. Further, when the preceding vehicle is lost during the follow-up travel mode, the target vehicle speed is calculated according to whether or not the curve travels after the holding time has elapsed, and during the curve travel, the target vehicle speed is calculated based on the curve curvature radius from the curve calculation unit 21. Is calculated. This target vehicle speed is output to the ECU 7. In the ECU 7, the throttle opening is feedback-controlled via an actuator that opens and closes the throttle valve according to the deviation between the target vehicle speed and the actual vehicle speed, and the vehicle speed of the host vehicle is controlled. .

  Specifically, the target vehicle speed in the above ACC control function is calculated by the program processing shown in FIG. Hereinafter, the target vehicle speed calculation routine of FIG. 4 will be described.

  This target vehicle speed calculation routine is started by the ON operation of the ACC main switch of the center display 10 under the ACC control executable condition, and is repeatedly executed at predetermined time intervals.

  When this routine starts, first, in step S101, the state transition calculated based on the preceding vehicle information from the IPU 5 is read. In step S102, the current state transition captures the preceding vehicle on the own vehicle travel lane. Check if there is no constant speed running mode. If the current state transition is the constant speed running mode, the process proceeds from step S102 to step S103, the set vehicle speed set by the driver is calculated as the target vehicle speed, and the routine is exited.

  In the constant speed running mode, the target vehicle speed is output from the PCU 6 to the ECU 7, and the ECU 7 feedback-controls the opening of the engine throttle valve so that the deviation between the target vehicle speed and the current host vehicle speed converges to zero. That is, when the throttle opening increases, the engine speed increases and the vehicle speed increases. Conversely, when the throttle opening decreases, the engine brake operates and decelerates. Thus, the host vehicle 1 is automatically controlled to travel at a constant speed at the vehicle speed set by the driver.

  In step S102, if the current state transition is not the constant speed travel mode, the process proceeds from step S102 to step S104, and the IPU 5 cannot capture the preceding vehicle due to curve traveling, lane change, etc. Check whether the lost judgment has been made.

  As a result, if the preceding vehicle is not lost and the preceding vehicle is properly captured on the own vehicle traveling lane, the process proceeds from step S104 to step S105, and the calculated value based on the appropriate inter-vehicle distance from the preceding vehicle. To calculate the target vehicle speed and exit the routine. At this time, the state transition becomes the follow-up running mode, for example, the target speed of the following vehicle is obtained by multiplying the speed of the own vehicle by the set time, and the target inter-vehicle distance and the actual inter-vehicle distance are obtained as the speed of the preceding vehicle. And a calculation value corresponding to the relative speed between the vehicle and the preceding vehicle is added to calculate the target vehicle speed.

  In the follow-up running mode in which the preceding vehicle is captured, the throttle valve opening is feedback-controlled in accordance with the deviation between the target vehicle speed output from the PCU 6 to the ECU 7 and the actual vehicle speed, so that the vehicle travel lane When there is an interrupt from another vehicle, etc., the inter-vehicle distance between the host vehicle and the preceding vehicle is controlled to be equal to the target inter-vehicle distance by performing deceleration by automatic braking from the PCU 6 via the VDC 8 as necessary. The As a result, the host vehicle 1 follows the vehicle while maintaining an appropriate inter-vehicle distance with respect to the preceding vehicle.

  On the other hand, if it is determined in step S104 that the preceding vehicle has been lost, the process proceeds to step S106, and the counter T for measuring the duration of the lost state is counted down from the previous value (T ← T-1). . The counter T is set with an initial value that gives a holding time (for example, 2 sec) for holding the current vehicle speed when the preceding vehicle is lost during the follow-up running, and is counted down from the initial value immediately after the lost.

  In a succeeding step S107, it is checked whether or not the counter T has reached zero. When T> 0 and the holding time after the preceding vehicle lost has not elapsed, the process proceeds from step S106 to step S107, the target vehicle speed is calculated as the current traveling speed of the host vehicle, and the routine is exited. Thereby, the current state transition changes from the follow running mode to the holding running mode.

  In the holding travel mode, the opening degree of the throttle valve is feedback-controlled in accordance with the deviation between the target vehicle speed output from the PCU 6 to the ECU 7 and the current vehicle speed, and the speed of the vehicle when the preceding vehicle cannot be captured. To maintain. That is, even if the preceding vehicle being followed cannot be captured, the current vehicle speed is maintained without immediately accelerating, a buffer zone for control is provided, and the driver is prevented from feeling uncomfortable.

  Thereafter, the routine is repeated, and when T ≦ 0 in step S107, and the lost state of the preceding vehicle has passed the holding time, the preceding vehicle is not temporarily lost and there is no preceding vehicle on the own vehicle travel lane ( It is determined that the preceding vehicle is in a disengaged state, and the process proceeds from step S107 to step S109 and thereafter, and the return control is performed.

  In this return control, in step S109, the presence / absence of a curve is determined based on information from the steering angle sensor. This curve determination is made based on, for example, whether or not the rudder angle detected by the rudder angle sensor exceeds a preset threshold value. If it is determined that the rudder angle is equal to or smaller than the threshold value and there is no curve, the above steps from step S109 are performed. By branching to S103 and setting the target vehicle speed to the set vehicle speed, acceleration is immediately started. When the target vehicle speed is changed due to the determination that there is no curve, the state transition changes to the constant speed running mode, and the driver quickly returns to the set vehicle speed without causing the driver to feel a sense of rattling (feeling of poor acceleration).

  If it is determined in step S109 that there is a curve determination, the process proceeds from step S109 to step S110, and an appropriate target vehicle speed is calculated based on a calculation value corresponding to the curve curvature radius based on the steering angle. For example, an allowable lateral acceleration assuming a general curve traveling is set in advance, and the target vehicle speed is calculated by adding a road gradient, a road surface friction coefficient, and the like to the turning speed based on the allowable lateral acceleration and the curve curvature radius. .

  When the target vehicle speed based on the steering angle is output from the PCU 6 to the ECU 7, the throttle valve opening is feedback-controlled in the valve closing direction, and the vehicle speed is decelerated by engine braking. At this time, if necessary, deceleration by automatic braking is also used from the PCU 6 via the VDC 8. During curve driving by this return control, unless the preceding vehicle is captured, the lost state continues and the state transition does not change, and after following the curve, the following traveling mode is maintained according to the capturing state of the preceding vehicle Or it becomes a constant speed driving mode.

  The change in the target vehicle speed due to the above curve approach will be described with reference to FIG. As shown in the figure, if the preceding vehicle enters the curve ahead and enters a lost state while following a preceding vehicle that is slower than the set vehicle speed set by the driver, the target vehicle speed will not change until the holding time elapses. When the holding time elapses, the target vehicle speed increases toward the set vehicle speed.

  Next, when the host vehicle actually enters the curve and the rudder angle changes, the target vehicle speed is changed according to the curve curvature radius determined by the rudder angle, and engine throttle control (in some cases, brake control is also used) As a result, the vehicle speed of the host vehicle is decelerated, and the target vehicle speed is changed as needed according to the change in the steering angle (change in the radius of curvature of the curve). Therefore. As indicated by a broken line in FIG. 5, the target vehicle speed does not rapidly increase toward the set vehicle speed after the holding time has elapsed, and the vehicle does not travel while accelerating. In the first half of the curve, weak acceleration corresponding to the curve or The acceleration gradually increases at a constant speed and the second half of the curve, and when the preceding vehicle is recognized / captured thereafter, the vehicle continues to follow.

  As a result, when the preceding vehicle is lost on a curve during follow-up driving, it will not enter the curve while accelerating against the driver's intention after the holding time has elapsed, and natural driving that is close to general curve driving It is possible to travel according to the driver's intention as a state, and it is possible to realize travel control with a small difference in behavior between when the preceding vehicle is lost and when it is not lost. Further, even if the preceding vehicle decelerates on a curve during follow-up traveling, the own vehicle can also ensure an appropriate inter-vehicle distance by using both engine control and brake control, and safety can be ensured.

  In the present embodiment, an example in which a preceding vehicle is captured by sensor fusion of a stereo image and a radar image has been described. However, either one of the preceding vehicles may be captured, or infrared light may be captured. The preceding vehicle may be captured by a combination with a laser radar or a monocular camera or by itself.

1 is a schematic configuration diagram of a vehicle equipped with a driving support device according to an embodiment of the present invention. Same as above, overall system configuration diagram of vehicle driving support device Same as above, block diagram of cruise control function Same as above, flowchart of target vehicle speed calculation routine As above, an explanatory diagram showing a change in the target vehicle speed after the preceding vehicle is lost Explanatory diagram showing the relationship between the vehicle in front and the vehicle running on the curve

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Own vehicle 2 Driving assistance device 3 Stereo camera unit 4 Millimeter wave radar unit 5 Image processing unit 6 Preview control unit 7 Engine control unit 20 State transition calculation part 21 Curve calculation part 22 Target vehicle speed calculation part

Agent Patent Attorney Susumu Ito

Claims (3)

Means for capturing the preceding vehicle on the traveling lane of the own vehicle based on the recognition result of the outside environment;
Means for detecting the presence or absence of a curve on the travel path when the preceding vehicle is lost during follow-up to the captured preceding vehicle;
A vehicle driving system comprising: means for accelerating / decelerating a target vehicle speed of the host vehicle according to a curvature radius of the curve when a set time has elapsed after the preceding vehicle is lost and the curve is detected Support device.   The vehicle driving support apparatus according to claim 1, wherein the presence or absence of the curve is detected based on steering angle information of the host vehicle.   The vehicle driving support apparatus according to claim 1, wherein the target vehicle speed is an instruction value for engine output control.

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