JP2006151066A - Travel support apparatus of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a travel support apparatus of a vehicle suitably controlling a travel support means by monitoring detection information of a navigation device and using only effective detection information. <P>SOLUTION: The difference between a road curvature which a second curvature obtaining means RC2 obtains from the navigation device NAV and a road curvature which a first curvature obtaining means RC1 obtains based on a travel lane that a travel lane detection means LD detects from an image of a road surface is compared with a predetermined value in accordance with the travel distance of the vehicle, and the travel support means AD(a lane keeping assist, a lighting for variably controlling the direction of illumination or the like) is controlled based on the result. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle driving support device, and more particularly, to a vehicle driving support device that detects a driving lane from an image obtained by continuously imaging a road surface by an imaging unit and supports driving of the vehicle according to the detection result. .

  Some vehicle driving support devices are provided with various driving support means. For example, a steering control means that operates according to the steering wheel operation of the driver and can control the steering state according to the road surface driving state of the vehicle. There is known a lane travel support device that controls this and assists the vehicle to travel in the travel lane. This lane driving support device is basically lane keeping assist, but further, beyond the driving support, the steering control is automatically performed regardless of the operation of the driver, and the vehicle can maintain the driving in the driving lane. Such a control device is also known.

  For example, in Patent Document 1 below, while searching for a traveling route, an optimal target route is set on the traveling route, and vehicle traveling control is performed to assist the vehicle traveling on the target route. An automatic traveling apparatus configured as follows has been proposed. That is, an appropriate target route is set in the travelable area while searching for the travelable area by recognizing the road edge based on the image obtained by capturing the area in the traveling direction of the vehicle by the imaging device. It is described that an optimal control target amount for joining the vehicle to the target route is obtained in accordance with the traveling state of the vehicle, and the vehicle is controlled according to the control target amount.

  Alternatively, in Patent Document 2 below, for example, a white line marked on both sides of the passage is used as a guide band in order to display a safety passage on the floor surface of a plant, factory, etc., and cornering in a narrow space is easy. For the purpose of being able to do so, the white line provided on the floor surface is used as it is as a guide band to show the limit of the safety passage, and the steering amount is calculated from the current direction of the traveling vehicle and the angle of the corner part A traveling vehicle guidance device configured to perform cornering has been proposed.

  Further, Patent Document 3 below proposes an automatic steering apparatus for an automobile that can travel without departing from the front traveling lane even if the driver does not operate the steering wheel. This Patent Document 3 includes a photographing means for photographing a path in the lower right direction of a car, a recognition means for recognizing a line indicating a boundary of an adjacent traveling lane among roads photographed by the photographing means, and this recognition. Distance detecting means for detecting the distance from the reference position of the line recognized by the means, steering angle control means for generating a steering angle control signal corresponding to the distance detected by the distance detecting means, and the steering angle control means A steering angle driving means for changing the traveling direction of the vehicle in response to a steering angle control signal from the vehicle, and a distance detected by the distance detection means by the operation of the steering angle control means by the steering angle control signal is predetermined. It is described that the value is held.

JP-A-2-48704 JP-A-2-27408 JP 60-37011 A

  According to the devices described in Patent Documents 1 to 3, cornering can be performed along a traveling lane of a vehicle or the like detected by an image. In this case, as a realistic response, it is not always necessary to automatically steer regardless of the operation of the driver. For example, the vehicle maintains the center of the traveling lane with respect to the steering wheel operation by the driver. By adding the steering torque in this way, the operation load on the steering wheel can be reduced and the cruise operation can be supported.

  In such a lane travel support device, it is important to appropriately and stably detect a travel lane on the road surface from an image captured by a camera. Usually, on the road surface, marking lines (lane marks) are painted according to various purposes including a lane boundary line that identifies the boundary of the driving lane (lane), not only a solid line but also a broken lane mark, There are lane marks of different colors such as white or yellow, and there are also those in which these are combined. In addition, the lane mark is not limited to a straight line, but there is a curved line. In order to obtain a curvature for specifying the lane mark of the curved line, it is necessary to reliably detect the lane mark far away. Therefore, a forward monitoring camera capable of detecting a lane mark with high accuracy to a long distance is required as an imaging unit provided for the lane travel support device. In addition, when the curvature in the vehicle traveling direction exceeds the specified curvature, the driving support is interrupted, but the interruption while driving on the road with a curved lane mark (curve) should be avoided. No specific workaround is shown.

  By the way, some recent vehicles are equipped with a front monitoring camera and a rear monitoring camera for confirmation of parking in front of or behind the vehicle and for parking assistance. However, these existing front and rear monitoring cameras can only secure a nearby image, and distant images are unclear, so the curvature in the traveling direction cannot be accurately determined for a curved lane mark. Therefore, it is necessary to obtain the curvature from the past travel locus and substitute it, but the existing camera is not diverted to detect such lane marks, and a high-performance front monitoring camera is adopted separately. It was an expensive device.

  On the other hand, although the navigation system is disclosed in the above-mentioned Patent Document 1, the recent progress of the navigation apparatus is remarkable, and the current position of the vehicle is determined with high accuracy using GPS (Global Positioning System) and inertial navigation. It has become possible to identify. Accordingly, the road shape information in the traveling direction of the vehicle can be detected by such a navigation device, and the position coordinates at a predetermined position in the traveling direction of the vehicle can be detected as the road shape information.

  However, when the position coordinates in the traveling direction of the vehicle are specified using only the detection information of the navigation device, the place depends on the accuracy of the navigation device, and a high-performance device is required and expensive. In addition, when the above-described high-performance front monitoring camera is required, it becomes a very expensive device, which is not completely worth the cost. Depending on the mode of the navigation device, the detected information may be different from the actual road shape information, and it is not appropriate to use the configuration in which the detected information of the navigation device is uniformly used for driving support for the vehicle.

  In addition, the travel support means in the vehicle travel support device is not limited to the means for performing the steering control as described above. For example, the irradiation direction of the headlamp is variably controlled so as to always irradiate the traveling direction of the vehicle. Alternatively, a lighting system that variably controls light distribution has been proposed and is already on the market, but such irradiation direction variable control means and light distribution variable control means are also included in the travel support means. In other words, by detecting the lane of the vehicle and controlling the direction of headlight illumination so that the lane is always illuminated, even during cornering, or by controlling the light distribution, it is easy to move around the lane at night. It is possible to assist in driving. Furthermore, in a vehicle equipped with an automatic transmission (not shown), automatic shift means for automatically shifting up and down depending on the degree of cornering operation of the vehicle (for example, the magnitude of the approach angle to the curve). On the other hand, by configuring so that the shift change can be automatically performed according to the detection result of the travel lane, it becomes an effective travel support means.

  Therefore, the present invention monitors the detection information of the navigation device in the vehicle travel support device that detects the travel lane from the images obtained by continuously capturing the road surface by the imaging means, and supports the travel of the vehicle according to the detection result. It is another object of the present invention to provide a vehicle driving support device that can appropriately control driving support means using only valid detection information.

  In order to achieve the above object, the present invention provides an imaging unit that captures an image of the periphery of a vehicle and outputs image information, and a traveling that detects a traveling lane of the vehicle from images obtained by continuously capturing a road surface by the imaging unit. Road shape information including position coordinates corresponding to a predetermined distance in the traveling direction of the vehicle, and lane detection means and travel support means for supporting the travel of the vehicle according to the travel lane detected by the travel lane detection means. A vehicle travel support apparatus comprising: a navigation device for detecting; a first curvature acquisition unit that acquires a road curvature in a traveling direction of the vehicle based on a detection result of the travel lane detection unit; and the vehicle from the navigation device. Second curvature acquisition means for acquiring road curvature in the traveling direction of the vehicle, road curvature acquired by the second curvature acquisition means and the first curvature acquisition means The difference between the road curvature, and compared with a predetermined value according to the running distance of the vehicle is obtained by a further comprising a monitoring control means for controlling the driving support unit on the basis of the comparison result. The travel support means includes lane travel support means for performing steering control so that the vehicle can travel in the travel lane, irradiation direction variable control means, light distribution variable control means, automatic transmission in the above lighting system. There is an automatic shift means.

  In the vehicle travel support apparatus, as described in claim 2, the monitoring control unit is configured to calculate a road curvature acquired by the second curvature acquisition unit and a road curvature acquired by the first curvature acquisition unit. When the state where the difference is less than the first predetermined value continues while the vehicle travels more than the first predetermined distance, the driving support means is changed based on the road curvature acquired by the second curvature acquiring means. It is good to comprise so that it may control.

  In addition to the above, the monitoring and control means may have a second difference between the road curvature acquired by the second curvature acquisition means and the road curvature acquired by the first curvature acquisition means as described in claim 3. When the vehicle continues for the second predetermined distance or longer, the control by the driving support means based on the road curvature acquired by the second curvature acquiring means is prohibited. It may be configured as follows. Further, as described in claim 4, when the monitoring control means prohibits the control of the travel support means based on the road curvature acquired by the second curvature acquisition means, the first curvature acquisition means You may comprise so that the said driving assistance means may be controlled based on the acquired road curvature.

  In addition, as described in claim 5, the travel support means operates according to a steering wheel operation by a driver of the vehicle and can control a steering state according to a road surface traveling state of the vehicle. And a state detection means for detecting a steering state and a traveling state of the vehicle including a yaw rate and a vehicle speed of the vehicle, a detection result of the traveling lane detection means, a steering state and a traveling state of the vehicle, Vehicle state quantity calculation means for calculating a state quantity including a relative position index representing a relative position of the vehicle to the travel lane, road curvature acquired by the second curvature acquisition means, and steering of the vehicle detected by the state detection means Target state quantity setting means for setting a target state quantity for the vehicle based on the state and the running state, and the target state quantity setting means sets May be the target state quantity vehicle state quantity calculating means for controlling said steering control unit according to a result of comparison between the state amount calculated.

  Further, as described in claim 6, the travel support means is a feedback control amount corresponding to a difference between the target state quantity set by the target state quantity setting means and the state quantity calculated by the vehicle state quantity calculation means. And the steering control by the steering control means may be corrected based on the sum of the feedforward control amount corresponding to the road curvature acquired by the second curvature acquisition means. Note that, as the index indicating the steering state and the running state of the vehicle in the vehicle state quantity calculating means, there are, for example, the steering angle and the yaw rate, and as the index indicating the steering state and the running state of the vehicle in the target state quantity setting means, For example, there are steering angle and body speed. The indicators representing the state quantity include a lane position that is a lateral position of the vehicle in the travel lane, a lane position fluctuation speed that is a differential value thereof, a yaw angle of the vehicle, and a yaw rate. The steering control means may include an electric power steering system, for example.

  Since this invention is comprised as mentioned above, there exist the following effects. That is, in the driving support apparatus according to claim 1, the first curvature is acquired based on the road curvature acquired by the second curvature acquisition unit from the navigation device and the driving lane detected by the driving lane detection unit from the road surface image. The difference between the road curvature obtained by the means is compared with a predetermined value according to the travel distance of the vehicle, and the travel support means is controlled based on the comparison result. Only the valid detection information can be utilized to appropriately control the driving support means.

  In the above driving support apparatus, the monitoring control means is configured as described in claim 2, so that the driving support means is appropriately set based only on the appropriate road curvature acquired by the second curvature acquisition means from the navigation device. Can be controlled.

  Further, by configuring the monitoring control means as described in claim 3, even if there is an error in the position coordinates detected by the navigation device, the road curvature obtained by the second curvature obtaining means based on this is obtained. Since the control based on this can be surely prohibited, the driving support means can be appropriately controlled. Further, according to the fourth aspect, the road curvature acquired by the first curvature acquisition unit even when the control of the driving support unit is prohibited based on the road curvature acquired by the second curvature acquisition unit. Based on the above, it is possible to continuously control the driving support means.

  According to the fifth aspect of the present invention, the driving support means uses only effective detection information out of the detection information of the navigation device without greatly depending on the accuracy of the imaging means, so that the vehicle travels in the lane. Support can be provided appropriately. Furthermore, if comprised as described in Claim 6, based on the detection information of a navigation apparatus, the lane driving assistance of a vehicle can be performed smoothly. Further, not only the front monitoring camera but also a rear monitoring camera can be used, and furthermore, an existing inexpensive camera can be used.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a vehicle driving support apparatus according to an embodiment of the present invention. An image pickup means CD for picking up an image of the periphery of the vehicle and outputting image information, and a road surface is continuously picked up by the image pickup means CD. A travel lane detection means LD for detecting a travel lane of the vehicle from the captured image, a travel support means AD for assisting the travel of the vehicle according to the travel lane detected by the travel lane detection means LD, and the traveling direction of the vehicle A navigation device NAV for detecting road shape information including position coordinates for a predetermined distance is provided. Furthermore, from the first curvature acquisition means RC1 for acquiring the road curvature ρe1 in the traveling direction of the vehicle based on the detection result of the traveling lane detection means LD and the navigation device NAV (for example, a predetermined distance in the detected traveling direction of the vehicle) There is provided second curvature acquisition means RC2 for acquiring a road curvature ρe2 in the vehicle traveling direction (based on the position coordinates). Then, in the monitoring control means WD, the difference between the road curvature ρe2 acquired by the second curvature acquisition means RC2 and the road curvature ρe1 acquired by the first curvature acquisition means RC1 is set to a predetermined value according to the travel distance of the vehicle. The driving support means AD is controlled based on the comparison result.

  In the monitoring control means WD, the state where the difference between the road curvature ρe2 acquired by the second curvature acquisition means RC2 and the road curvature ρe1 acquired by the first curvature acquisition means RC1 is less than the first predetermined value ρemax1. When the vehicle continues for the first predetermined distance D1 or more, the driving support means AD is controlled based on the road curvature ρe2 acquired by the second curvature acquiring means RC2. In addition, the state in which the difference between the road curvature ρe2 acquired by the second curvature acquisition unit RC2 and the road curvature ρe1 acquired by the first curvature acquisition unit RC1 is equal to or larger than a second predetermined value ρemax2 is When the vehicle travels for a predetermined distance D2 or longer, control by the travel support means AD based on the road curvature ρe2 acquired by the second curvature acquisition means RC2 is prohibited. This specific example will be described later with reference to FIG.

  As described above, the travel support means AD includes an irradiation direction variable control means and a light distribution variable control means in a lighting system (not shown), and steering control is performed so that the vehicle can travel in the travel lane. A lane traveling support device that performs That is, as indicated by a broken line in FIG. 1, a steering control means SC that operates according to a steering wheel operation by a vehicle driver and can control a steering state according to a road running state of the vehicle, a yaw rate of the vehicle, and a vehicle body A relative position representing a relative position of the vehicle with respect to the traveling lane according to the detection result of the traveling lane detecting unit LD, the steering state and the traveling state of the vehicle, the state detecting unit SD for detecting the steering state and the traveling state of the vehicle including the speed Target state quantity for the vehicle based on the vehicle state quantity computing means SA for computing the state quantity including the index, the road curvature obtained by the second curvature obtaining means RC2, and the steering state and running state of the vehicle detected by the state detecting means SD. It may be provided with target state quantity setting means ST for setting.

  Thus, the steering control means SC is controlled according to the comparison result between the set target state quantity of the target state quantity setting means ST and the state quantity of the calculation result of the vehicle state quantity calculation means SA. For example, the feedback control amount corresponding to the difference between the set target state quantity of the target state quantity setting means ST and the state quantity of the calculation result of the vehicle state quantity calculation means SA, and the road curvature ρe2 acquired by the second curvature acquisition means RC2. The steering control by the steering control means SC is corrected based on the sum of the feedforward control amount corresponding to the steering control means SC.

  FIG. 2 shows an embodiment of the above-described lane driving support apparatus. A front monitoring camera CMf configured by, for example, a ccd camera as an imaging unit is arranged in front of the vehicle (upper side in FIG. 2). Although a rear monitoring camera CMr is also arranged behind the vehicle, any one of the cameras may be provided. Moreover, an electric power steering system EPS is provided as the steering control means of the present embodiment. Such an electric power steering system EPS is already on the market, and the steering torque acting on the steering shaft by the operation of the steering wheel SW by the driver is detected by the steering torque sensor TS, and according to the value of the detected steering torque. Controls the EPS motor (not shown in FIG. 2), steers the wheel in front of the vehicle (represented by WH as representative of all wheels in FIG. 2) via a reduction gear and a rack and pinion (not shown), and operates This reduces the operator's steering operation force (steering operation force).

  In this embodiment, as shown in FIG. 2, an electronic control unit ECU1 for image processing and an electronic control unit ECU2 for steering control are provided, and both are connected via a communication bus. A camera CMf (and CMr) is connected to the electronic control unit ECU1, and an image signal is input to the electronic control unit ECU1. Further, a steering angle sensor SS that detects the steering angle of the wheel WH ahead of the vehicle, a vehicle body speed sensor VS that detects the vehicle body speed, and a yaw rate sensor YS that detects the yaw rate of the vehicle are connected to the electronic control unit ECU1. However, since the electronic control units ECU1 and ECU2 are configured to be able to transmit and receive signals to each other as will be described later, they may be connected to the electronic control unit ECU2. Instead of the vehicle body speed sensor VS, a wheel speed sensor (not shown) for detecting the wheel speed of each wheel may be provided, and the vehicle body speed may be estimated based on the detected wheel speed. On the other hand, the electronic control unit ECU2 is connected to the steering torque sensor TS and the rotation angle sensor RS for detecting the rotation angle of the EPS motor on the input side, and to the EPS motor on the output side.

  Furthermore, a navigation device NAV equipped with GPS and inertial navigation is connected to the electronic control unit ECU1 (or ECU2), and road shape information in the vehicle traveling direction detected thereby is input to the electronic control unit ECU1. . The road shape information at this time includes position coordinates at a predetermined position in the vehicle traveling direction, and the navigation device NAV can use a commercially available device as long as it can extract the position coordinates at the predetermined position in the vehicle traveling direction. Since the basic configuration may be the same as that of a commercially available apparatus, description thereof is omitted.

  FIG. 3 shows a system configuration of the present invention. An image processing system (upper part of FIG. 3) and a steering control system (lower part of FIG. 3) are connected via a communication bus. The image processing system according to this embodiment includes an electronic control unit ECU1 including a CPU for image processing, a frame memory, and the like, a front monitoring camera CMf and a rear monitoring camera CMr, a yaw rate sensor YS, a steering angle sensor SS, and a vehicle body speed sensor VS. And a navigation device NAV. Further, in the steering control system of the present embodiment, a steering torque sensor TS and a rotation angle sensor RS are connected to an electronic control unit ECU2 having a CPU, ROM and RAM for electric power steering control, and a motor drive circuit AC2 is used. An EPS motor MT is connected via

  These electronic control units ECU1 and ECU2 are each connected to a communication bus via a communication unit having a communication CPU, ROM, and RAM, and transmit information necessary for each control system from other control systems. be able to. Further, although not shown in the figure, an active steering system, a brake control system, a throttle control system, etc. may be connected to the communication bus so that each system can share system information. Good. As shown in FIG. 2, an operation switch OS is connected to the electronic control unit ECU1 (or ECU2), and the driving support control is started by the operation of the operation switch OS by the driver. .

  In the lane travel support apparatus configured as described above, the lane travel support (lane keep assist) control unit is configured as shown in the control block diagram of FIG. 4 and is captured by the camera CMf (or CMr). The image information is image-processed by the electronic control unit ECU1 shown in FIGS. 2 and 3 to detect the traveling lane. The electronic control unit ECU1 includes a lane recognition calculation unit M1 serving as lane detection means. Here, the lateral position y (lane position) of the vehicle in the travel lane and the yaw angle ψ relative to the travel lane are calculated. The In addition, about the detection of the driving | running lane by image processing, any well-known method other than the method described in the above-mentioned patent document 1 may be used.

Based on the calculation result by the lane recognition calculation unit M1 and the detection signals of the yaw rate sensor YS and the steering angle sensor SS, the lane position y and the lane lateral movement speed dy ( The current vehicle state quantity X is estimated and calculated by using the lateral movement speed of the vehicle in the travel lane and the yaw angle ψ and the yaw rate γ as factors. That is, if the vehicle state quantity is X, the state quantity output is Y, and the road model input is U, X = [y, dy, ψ, γ] ^T , Y = [y, dy, ψ, γ] ^T , U = [δf, ρ] ^T. Note that δf is a steering angle detected by the steering angle sensor SS, and ρ is a road curvature of the road, for example, estimated from the above-described camera image (road curvature ρe1 described later). When the state quantity estimated value is Xe and the observer gain is L, the following state equation is established, and the state quantity output Y is Y = C · Xe.
dXe / dt = A.Xe + B.U + Rl.L. (X-Xe)

The model constants A, B, and C in the above state equation are as shown below.
A = [a11 a12 a13 a14; a21 a22 a23 a24; a31 a32 a33 a34; a41 a42 a43 a44]
B = [b11 b12; b21 b22; b31 b32; b41 b42]
C = [1 0 0 0; 0 1 0 0; 0 0 1 0; 0 0 0 1]
Rl is a factor indicating the lane detection state of the image recognition result. For example, the state where the traveling lane is detected is “1”, and the state where the lane is not detected is “0”. Thus, the configuration is such that the lateral position of the vehicle in the travel lane is estimated only when the continuous line portion of the lane mark is detected, or the travel lane is only detected when the continuous line portion of the lane mark is detected. The lateral position of the vehicle in the vehicle can be reflected in the estimation result.

  On the other hand, a relative position index representing the relative position of the vehicle with respect to the travel lane is calculated in the state quantity calculation unit M2, and based on the relative position index, the detected yaw rate of the yaw rate sensor YS, and the detected vehicle speed (vehicle speed Vx) of the vehicle speed sensor VS. The first curvature acquisition unit M6 acquires the road curvature ρe1. FIG. 5 shows a travel lane center trajectory (solid line) on absolute coordinates and a travel trajectory (broken line) of the vehicle VH. The position coordinates of the lane center are represented by (xlc, ylc), and the vehicle position coordinates are represented by (xv, yv). In the figure, Ca indicates the arc center of the traveling lane center locus.

The algorithm in the first curvature acquisition unit M6 in the present embodiment is as follows. That is, the plane lane coordinates (absolute coordinates) shown in FIG. 5 are generated based on the vehicle lane position y obtained on the image as described above, and the vehicle position coordinates are calculated based on the detected yaw rate γ and the vehicle speed Vx. The position coordinate at the center of the lane is calculated based on the calculation result and the lane position y, and this is stored and the curvature is calculated by the method of least squares. Specifically, first, the position coordinates (xv, yv) of the vehicle are obtained as follows based on the detected yaw rate γ and the vehicle speed Vx for each control cycle.
xv = ∫∫Vx · cos (ψ + β) dt dt = ΣVx · Δt · cos (ψ + β)
yv = ∫∫Vx · sin (ψ + β) dt dt = ΣVx · Δt · sin (ψ + β)

The yaw angle ψ in the above equation can be obtained as ψ = ∫γdt based on the yaw rate γ, and the side slip angle (slip angle) β can be obtained by the following equation.
β = [{1- (Mv / 2L) ・ Lf / (Lr ・ Cr)} / (1 + K ・ Vx ² )] ・ (Lr / L) ・ δf
Where Mv is the vehicle body mass, L is the wheel base, Lf and Lr are the distance between the center of gravity of the vehicle and the center of the front wheel axle and the center of the rear wheel axle (L = Lf + Lr), and Cr is the cornering factor of the rear wheel , K is the stability factor, Vx is the vehicle speed, and δf is the steering angle.

Next, every time the lane position y is acquired, the position coordinates of the lane center offset from the position coordinates of the vehicle are obtained. Basically, calculation is performed so that the yaw angle ψ is zero with respect to the vehicle traveling direction, and if the error is large, the measured yaw angle is corrected. That is, the position coordinates (xlc, ylc) at the center of the lane are the offsets in the direction perpendicular to the position coordinates (xv, yv) of the vehicle at the time of measurement of the lane position y (the lane position at the time of measurement is yc). Addition can be obtained as follows.
xlc = xv + (-yc) .cos (ψ + 90deg)
ylc = yv + (-yc) · sin (ψ + 90deg)

  Thus, if a part of the lane center position coordinates (xlc, ylc) is extracted from the past, and the lane center trajectory is assumed to be a circular arc and the circle parameter is obtained by the method of least squares, the radius becomes It becomes the road diameter, and its curvature is the road curvature ρe1.

  Moreover, as shown in FIG. 6, among the road shape information (map coordinates) detected by the navigation device NAV, position coordinates for a predetermined distance in the traveling direction (front) of the vehicle (VH indicated by a broken line in FIG. 6). Is input to the second curvature acquisition unit M7 (FIG. 4), where the road curvature ρe2 at a position separated by a predetermined distance in the traveling direction (forward) of the vehicle VH is acquired. Specifically, an arc is fitted to several points among a plurality of road coordinate points (position coordinates indicated by black points in FIG. 6) detected by the navigation device NAV, and the curvature of the arc is obtained. In order to fit the arc to the road position coordinates at this time, for example, a method of obtaining an arc passing through three points or a method of obtaining an arc so as to minimize the square error from coordinates of four or more points (least square method). Apply.

  The road curvature ρe2 estimated as described above is input to the target state quantity calculator M3 in FIG. 4, and the target state quantity calculator M3 calculates the target state quantity based on the road curvature ρe2 as follows. . That is, based on the road curvature ρe2 acquired by the second curvature acquisition unit M7 in addition to the steering angle δf detected by the steering angle sensor SS, the vehicle speed (vehicle speed Vx) detected by the vehicle speed sensor VS, and the like, A target state quantity calculation unit M3 calculates a target state quantity consisting of the following four factors.

  First, the target lane position yt relative to the lateral position (lane position) of the vehicle in the travel lane is set to yt = 0 starting from the center of the travel lane (center between lane boundary lines). Then, with respect to the target lane lateral movement speed dyt, dyt = 0 is set so that the vehicle moves along the center of the travel lane without sideways swinging. Further, the target yaw angle ψt is set to ψt = C · ρ. This C is a conversion constant from the road curvature ρe2 to the target yaw angle ψt. Then, based on the vehicle body speed (vehicle speed) Vx and the road curvature ρe2, the target yaw rate γt is set as γt = Vx · ρe2.

Thus, the difference between the calculation result (target state quantity) of the target state quantity calculation unit M3 and the calculation result (current state quantity) of the state quantity calculation unit M2 is calculated, and based on this difference, the feedback control calculation unit A torque command value is calculated at M4. That is, in the feedback control calculation unit M4, the difference between the 4-factor target value (t is added) and the estimated value (e is added) representing the target state quantity is weighted by the control gains K1 to K4. An error feedback term for the lateral displacement is formed, and a steering angle feedforward term δff (ρe2) corresponding to the road curvature ρe2 is added to the sum of these, and the target rotation angle (target steering angle) δswt is as follows: Is set.
δswt = K1 ・ (yt−ye) + K2 ・ (dyt−dye) + K3 ・ (ψt−ψe) + K4 ・ (γt−γe) + δff (ρe2)

The above δff (ρe2) is calculated as the steering angle theoretical value in the road curvature derived from the two-wheel model as follows (where Vx is the vehicle speed, L is the wheelbase, and K is the stability factor) ).
δff (ρe2) = Vx · ρe2 / Vx · L (1 + K · Vx ² )

Then, according to the difference between the target rotation angle (target steering angle) δswt and the actual rotation angle (actual steering angle) δsw detected by the rotation angle sensor RS, and the additional steering torque feedforward term Tff (ρe2) The additional steering torque command value Tadd is calculated as follows (where K5 is a control gain).
Tadd = K5 · (δswt−δsw) + Tff (ρe2)
The additional steering torque feedforward term Tff (ρe2) is calculated as follows.
Tff (ρe2) = fatff (βff (ρe2) + δff (ρe2))

In the above equation, fatff (α) is a function representing the self-aligning torque with respect to the tire slip angle (α). Βff (ρe2) is a steady vehicle body slip angle at the road curvature ρe2, and is obtained as follows. The steady vehicle body slip angle is the vehicle body slip angle when traveling on a road having a constant road curvature at a constant vehicle speed.
βff (ρe2) = [{1− (Mv / 2L) ・ (Lf / (Lr ・ Cr)) ・ Vx ² } / (1 + K ・ Vx ² )] ・ (Lr / L) ・ δff (ρe2)
Where Mv is the vehicle body mass, L is the wheel base, Lf is the distance from the center of gravity of the vehicle to the center of the front axle, Lr is the distance from the center of gravity of the vehicle to the center of the rear axle, Cr is the cornering factor of the rear wheel, and Vx is Vehicle speed and K are stability factors.

  The additional steering torque command value Tadd calculated as described above is transmitted to the electronic control unit ECU 2 (FIG. 3) for steering control, and the torque command value Tadd is normally set by the electric power steering control unit M5 (FIG. 4). The electric power steering system EPS is controlled by being added to the power steering control amount, and corrective steering is performed. Further, if necessary, the torque command value Tadd is supplied to an alarm output unit (not shown), and depending on the magnitude of the torque command value Tadd, in other words, the position of the vehicle from the center of the travel lane, A warning indicating the possibility of departure from the vehicle is output, and the driver is alerted. In addition, it is good also as issuing a warning according to the estimation result (calculation result of the state quantity calculating part M2) of the horizontal position of the vehicle in a driving | running lane, without using torque command value Tadd.

Alternatively, as shown in FIG. 7, of road shape information (map coordinates) detected by the navigation device NAV, a position at a predetermined position in the traveling direction (front) of the vehicle (VH indicated by a broken line in FIG. 7). You may comprise so that this position coordinate may be input into electronic control unit ECU1 using a coordinate. Specifically, as shown in FIG. 7, from a plurality of road coordinate points (position coordinates indicated by black dots in FIG. 7) detected by the navigation device NAV, the least square method or the like is used as described above. The road curvature (ρe1) in the vicinity of the vehicle position is estimated, and xy coordinates are set with the vehicle VH's vehicle position as the origin and the axis parallel to the tangent shown by the two-dot chain line in FIG. The Then, the x coordinate value (xlt) of the target coordinate point (intersection point x in FIG. 7) in the vehicle traveling direction is set based on the vehicle speed Vx of the vehicle VH, and further the y coordinate value (ylt) based on the x coordinate value (xlt). ) Is calculated as follows (note that R below is R = 1 / ρe2).
ylt = (yt−ye) + R ・ (1−cos (sin ⁻¹ (xlt / R))

Thus, the target steering angle (δswt) is set as follows according to the lateral displacement (ylt−xlt · tan (ψ + Vx · γ)) at the target coordinate point in the vehicle traveling direction (K6 is Control gain).
δswt = K6 ・ (ylt−xlt ・ tan (ψ + Vx ・ γ))

Thereafter, as in the above-described embodiment, the additional steering torque command value Tadd is calculated as follows, and feedback according to the displacement in the lateral direction of the vehicle is performed, and thereafter, the same processing as in the above-described embodiment is performed ( K7 is a control gain).
Tadd = K7 ・ (δswt−δsw)

  On the other hand, the monitoring control unit M8 obtains the difference between the road curvature ρe1 acquired by the first curvature acquisition unit M6 and the road curvature ρe2 acquired by the second curvature acquisition unit M7. As shown in FIG. 8, it is compared with the first predetermined value ρemax1 or the second predetermined value ρemax2 according to the travel distance of the vehicle. As a result, the road curvature (ρe1) from the road locus indicated by the broken line in FIG. 8 and the map coordinates indicated by the solid line in FIG. When the state in which the difference from the road curvature (ρe2) is equal to or greater than the second predetermined value ρemax2 continues while the vehicle travels for the second predetermined distance D2 (point a in FIG. 8), the monitoring control unit A control prohibition command is output from M8 to the feedback control calculation unit M4, and control based on the road curvature ρe2 is prohibited.

  As shown in FIG. 8, when the state where the difference between the road curvature ρe1 and the road curvature ρe2 is less than the first predetermined value ρemax1 continues while the vehicle travels more than the first predetermined distance D1 (FIG. 8). 8 at point b), a control permission command is output from the monitoring control unit M8 to the feedback control calculation unit M4, and control based on the road curvature ρe2 is permitted. In this case, the determination criteria for the control prohibition and the control permission are set to be different. For example, in order to make the determination on the control permission side more strict, it is preferable to set ρemax1 <ρemax2 and D1> D2.

  As described above, the travel support means AD shown in FIG. 1 includes the lane travel support apparatus shown in FIGS. 2 to 8, and the irradiation direction variable control means in the lighting system (not shown) as described above. There is a variable light distribution control means, an automatic shift means for an automatic transmission (not shown), etc., but in these cases, for example, the electric power steering control section M5 in FIG. 4 is replaced with a drive control section such as an actuator. That's fine. Since FIGS. 5 to 8 can be applied as they are, the illustration is omitted.

1 is a block diagram showing an embodiment of a vehicle travel support apparatus of the present invention. It is a block diagram of the lane driving assistance device in one embodiment of the present invention. It is a block diagram which shows the structural example of the lane travel assistance apparatus containing the steering control means in one Embodiment of this invention. It is a block diagram which shows the control aspect of lane driving assistance in one Embodiment of this invention. It is a graph which shows an example of the own vehicle locus road curvature data sequence used for the 1st curvature acquisition in one embodiment of the present invention. It is a graph which shows an example of the navigation road curvature data sequence used for 2nd curvature acquisition in one Embodiment of this invention. It is a graph which shows the example of a setting of the target coordinate point with which it uses for the other aspect of target state quantity calculation in one Embodiment of this invention. It is a graph which shows an example of change according to vehicle travel distance of two road curvatures used for lane travel support in one embodiment of the present invention.

Explanation of symbols

SW Steering wheel VH Vehicle WH Wheel EPS Electric power steering system NAV Navigation device CMf Front monitoring camera CMr Rear monitoring camera TS Steering torque sensor SS Wheel steering angle sensor RS Rotation angle sensor YS Yaw rate sensor VS Car body speed sensor OS Operation switch

Claims (6)

  Imaging means for imaging the periphery of the vehicle and outputting image information, traveling lane detecting means for detecting the traveling lane of the vehicle from images obtained by continuously imaging the road surface by the imaging means, and detecting by the traveling lane detecting means The vehicle travel support includes a travel support means for supporting the travel of the vehicle according to the travel lane, and a navigation device that detects road shape information including position coordinates for a predetermined distance in the traveling direction of the vehicle. In the apparatus, a first curvature acquisition unit that acquires a road curvature in the traveling direction of the vehicle based on a detection result of the traveling lane detection unit, and a second curvature that acquires the road curvature in the traveling direction of the vehicle from the navigation device. The difference between the curvature acquisition means and the road curvature acquired by the second curvature acquisition means and the road curvature acquired by the first curvature acquisition means Drive assist system for a vehicle, characterized in that compared with a predetermined value, having a monitoring control means for controlling the driving support unit on the basis of the comparison result according to.   In the monitoring control means, the vehicle is in a state where the difference between the road curvature acquired by the second curvature acquisition means and the road curvature acquired by the first curvature acquisition means is less than a first predetermined value. 2. The vehicle according to claim 1, wherein, when the vehicle travels for a predetermined distance or longer, the travel support unit is controlled based on the road curvature acquired by the second curvature acquisition unit. Driving support device.   In the monitoring control means, the vehicle is in a state where the difference between the road curvature acquired by the second curvature acquisition means and the road curvature acquired by the first curvature acquisition means is greater than or equal to a second predetermined value. 3. The control according to claim 2, wherein the control by the driving support means based on the road curvature acquired by the second curvature acquiring means is prohibited when the vehicle continues for a distance of 2 or more. Vehicle travel support device.   When the monitoring control unit prohibits the control of the driving support unit based on the road curvature acquired by the second curvature acquisition unit, the monitoring control unit determines the driving support unit based on the road curvature acquired by the first curvature acquisition unit. 4. The vehicle travel support device according to claim 3, wherein the vehicle travel support device is controlled.   The travel support means includes a steering control means that operates according to a steering wheel operation by a driver of the vehicle and can control a steering state according to a road surface traveling state of the vehicle, and includes a yaw rate and a vehicle body speed of the vehicle. A relative position representing a relative position of the vehicle with respect to the travel lane according to a detection result of the travel lane detection unit and a detection result of the travel lane detection unit and the steering state and the travel state of the vehicle; Vehicle state quantity calculating means for calculating a state quantity including an index; road curvature acquired by the second curvature acquisition means; and a target state for the vehicle based on the steering state and running state of the vehicle detected by the state detection means Target state quantity setting means for setting an amount, and the target state quantity set by the target state quantity setting means and the vehicle state quantity calculating means Driving support apparatus for a vehicle according to any one of claims 1 to 3, characterized by being configured to control said steering control unit according to a result of comparison between the state quantity. The driving support means is acquired by the feedback control amount according to the difference between the target state quantity set by the target state quantity setting means and the state quantity calculated by the vehicle state quantity calculating means, and the second curvature acquisition means acquires 6. The vehicle travel support apparatus according to claim 5, wherein the steering control by the steering control means is corrected based on a sum of the feedforward control amount corresponding to the road curvature.

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