JP2010137657A - Lane keeping assist system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lane keeping assist system which does not cause complicated steering operation. <P>SOLUTION: This lane keeping assist system 1 of includes a picturing means 10 for imaging a view ahead of a vehicle C, an offset distance and a deflection angle of the vehicle for the lane center ahead of the vehicle C from an image of the view ahead imaged by the picturing means 10, a detection means 8a for detecting a curvature of the lane center and a lane keeping means 8b for outputting a steering instruction for a steering control device for controlling a steering device 6 of the vehicle so that the vehicle is kept at the lane center based on the offset distance, the deflection angle and the curvature. The steering device 6 includes a steering angle variable mechanism 3 for allowing a gear ratio to be variable which is calculated by dividing an input side steering angle of a driving shaft 2 by an output side steering angle of an output side driving shaft 4 and a gear ratio change means 8c for changing the gear ratio based on the curvature detected by the detection means 8a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lane keeping support system suitable for being applied to vehicles such as passenger cars, trucks, and buses.

In recent vehicles, when the vehicle is traveling on an automobile exclusive road, an expressway, or the like, the road surface ahead of the vehicle is imaged with a CCD camera or the like including white lines on both sides of the lane where the vehicle is currently located. Then, by binarizing the captured image, etc., the white line on both sides is recognized, the center of the lane that is the center of the white line is recognized, the curvature of the road surface that is the locus of this lane center, and the center of the lane An EPS (which configures a vehicle steering system) detects an offset distance and a deflection angle of the vehicle and maintains the vehicle as centered as possible on the basis of the curvature, the offset distance, and the deflection angle. Lane ECU (LKA ECU: Lane Keep Assist Electronic Control Unit) or LDWEC for EPSECU (Electronic Power Steering Electronic Control Unit) that controls Electronic Power Steering (Lane Departure Warning Electronic Control Unit) is sometimes lane keeping assistance system for performing control to output the steering torque assist command is mounted.
JP 2007-326534 A

  However, in such a lane keeping support system as described in Patent Document 1, noise detected due to misrecognition may be included in the detected curvature of the road surface. In order to prevent this, even if noise is removed with a filter, for example, noise caused by misrecognition that lasts for several seconds or more cannot be completely removed, and is unnecessary by the EPS constituting the steering device. Steering torque is generated, and it is necessary for the driver to steer in a direction to cancel out such unnecessary steering torque, and it is necessary to suppress unnecessary behavior of the vehicle in the left-right direction due to unnecessary steering torque.

  Even if unnecessary steering torque is generated in this way, the driver performs interventional steering in a direction to cancel the unnecessary steering torque, so the driver holding the steering wheel does not need unnecessary steering. Torque generation can be immediately perceived, and interventional steering will suppress unnecessary left-right behavior of the vehicle due to unnecessary steering torque, but is not required until the driver performs intervention steering As a result, unnecessary lateral behavior of the vehicle due to a large turning torque occurs and the vehicle deflects, and the driver needs to steer in a direction to cancel the deflection, which makes the steering operation complicated. Arise.

  In view of the above problems, an object of the present invention is to provide a lane keeping support system that does not cause a complicated steering operation.

To solve the above problem,
The lane keeping support system according to the present invention includes:
Imaging means for imaging the front of the vehicle;
An offset distance and a deflection angle of the vehicle with respect to a lane center in front of the vehicle from the front image captured by the imaging means;
Detecting means for detecting the curvature of the lane center;
Lane maintaining means for outputting a steering command to a steering control device that controls the steering device of the vehicle so as to maintain the vehicle at the center of the lane based on the offset distance, the deflection angle, and the curvature, and
The steering device includes a steering angle variable mechanism that varies a gear ratio obtained by dividing an input side steering angle of an input side drive shaft by an output side steering angle of an output side drive shaft,
Gear ratio changing means for changing the gear ratio based on the curvature detected by the detecting means,
It is characterized by providing.

Here, in the lane keeping support system,
Preferably, the gear ratio changing unit increases the gear ratio when the curvature is equal to or greater than a predetermined threshold.

  The steering device includes, for example, a steering wheel, an input side column shaft, an intermediate column shaft, a rack and pinion mechanism, and a torque assist mechanism. The input side column shaft constitutes the input side drive shaft. The column ASSY is rotatably supported and has a function of transmitting an input side steering angle input by a driver to the steering wheel.

  Further, the steering angle variable mechanism is a VGRS (Variable Gear Ratio System) configured by an eccentric pin mechanism including an eccentric pin and an eccentric cam, for example, and is disposed on the downstream side of the column shaft on the input side. It is possible to make the gear ratio obtained by dividing the input side steering angle input to the side column shaft by the output side steering angle input to the intermediate column shaft non-linear. For example, the change of the output side steering angle with respect to the change of the input side steering angle is moderated near the neutral position of the steering wheel, and the change of the output side steering angle with respect to the change of the input side steering angle is more than a certain degree of the input side steering angle The gear ratio is changed according to the vehicle speed by detecting the vehicle speed. For example, in the region where the vehicle speed is low, the gear ratio is smaller than the region where the vehicle speed is high. The control of performing etc. is performed.

  According to the lane keeping assist system of the present invention, the gear ratio changing unit changes a gear ratio obtained by dividing the input side steering angle of the input side drive shaft of the steering device by the output side steering angle of the output side drive shaft. Since it can be made possible, the degree of freedom in control can be increased in removing noise, and the following advantageous operational effects can be obtained.

  That is, when the curvature detected by the detecting means is equal to or greater than the predetermined threshold, the gear ratio changing means outputs the input side steering angle of the input side drive shaft of the steering device to the output side drive shaft output. Since the gear ratio divided by the side steering angle can be made larger than normal, when the curvature detected by the detection means is greater than or equal to the predetermined threshold, the steering is caused by noise included in the curvature. When the device generates unnecessary steering torque and unnecessary steering due to misrecognition occurs, the steering wheel of the steering device is rotated at a larger angle, so the unnecessary steering occurs. This can be recognized by the driver at a timing earlier than in the prior art. Note that the turning angle by the steering device can be set as usual.

  As a result, intervention steering can be executed by the driver at an earlier timing, so that the vehicle is prevented from being deflected by the unnecessary steering as much as possible, and unnecessary steering of the driver is reduced as much as possible. A complicated steering operation can be omitted.

  According to the present invention, it is possible to provide a lane keeping support system that does not cause a complicated steering operation.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a lane keeping support system according to the present invention. FIG. 2 is a schematic diagram showing an embodiment of a lane keeping support system according to the present invention. FIG. 3 is a schematic diagram showing characteristics of an embodiment of the lane keeping support system according to the present invention.

  As shown in FIG. 1, a lane keeping assist system 1 of this embodiment includes a steering wheel 2, an input side column shaft 2 connected to the steering wheel, a VGRS 3, an intermediate column shaft 4, and a steering torque sensor. 5, an automatic steering actuator 6, a vehicle speed detection device 7, a lane keeping branch system ECU 8, a direction indicator 9, and a forward lane detection camera 10.

  The steering wheel 1 is provided at an end of the column shaft 2 that extends so as to be directed rearward and upward of the vehicle C and protrudes into the vehicle interior, and receives the steering force of the driver. is there.

  The column shaft 2 constitutes an input side drive shaft that transmits the steering force of the driver input from the steering wheel 1 to the input gear constituting the VGRS 3, and is rotated by a column ASSY (not shown) via a bearing (not shown). It is supported freely.

  The speed reduction mechanism included in the VGRS 3 is composed of an input side small gear and an output side large gear. The input side small gear is drivingly coupled to the column shaft 2, and the output side large gear is driven to the intermediate column shaft 4. Combined. A cylindrical female shape is formed on the output side of the large gear on the input side, and is connected to a cylindrical male shape protruding to the input side of an eccentric cam (not shown) by serration or key coupling. The outer peripheral surface of the eccentric cam is rotatably supported by the column ASSY via a bearing (not shown).

  A cam groove extending in the diametrical direction is formed on the surface of the eccentric cam that faces the adapting plate, and the cam groove is slidably fitted to an eccentric pin provided in the adapting plate. The central axis of the eccentric cam is provided eccentrically by a first eccentric amount with respect to the central axis of the adapting plate.

  The eccentric pin is rotatably provided on the surface of the adapting plate facing the eccentric cam at a position eccentric from the central axis of the adapting plate by a second eccentric amount larger than the first eccentric amount. The eccentric pin and the cam groove of the eccentric cam constitute an eccentric pin mechanism, whereby the steering angle of the input-side column shaft 2 that is the input-side drive shaft is changed to the intermediate column that is the output-side drive shaft. A steering angle variable mechanism that varies the gear ratio divided by the steering angle of the shaft 4 is configured. Note that the detailed structure is the same as a well-known structure, and therefore a detailed description is omitted here.

  The VGRS 3 configured as described above is configured so that the operation angle of the steering force transmitted from the input side column shaft 2 is changed to an intermediate position on the output side by meshing the small gear on the input side and the large gear on the output side. A steering angle variable mechanism is configured that decelerates with a variable gear ratio with respect to the steering angle of the column shaft 4 and changes the gear ratio based on the vehicle speed detected by the vehicle speed detection device 7.

  The intermediate column shaft 4 is provided with a steering torque sensor 5, detects the steering force input by the driver through the steering wheel 1, and outputs the detection result to the lane keeping assist system ECU 8.

  The direction indicator 9 is operated when the driver intends to change the course, and blinks the blinkers located on both the front, rear, left and right sides of the vehicle C.

  The forward lane detection camera 10 is installed on the windshield of the vehicle and constitutes imaging means for imaging the road surface in front of the vehicle including the white lines on both sides. The captured forward image information is obtained from the lane keeping support system ECU8. Is output.

  The lane keeping support system ECU8 is composed of, for example, a CPU, a ROM, a RAM, and a data bus for interconnecting them, and the CPU performs the processing described below in accordance with a program stored in the ROM. Based on the image information captured by the camera 10, the white line on both sides of the lane where the vehicle is located is recognized, the lane center, lane width and curvature are detected, and the offset distance and deflection angle from the lane center of the vehicle are detected. And a lane maintaining means 8b for outputting a steering command to EPSECU, which is a steering control means for controlling EPS that constitutes the steering device, so that the vehicle maintains the center of the lane. Gear ratio changing means 8 for changing the gear ratio of VGRS 3 to be larger than normal when the detected curvature is equal to or greater than a predetermined threshold. It constitutes a.

  An EPS ECU (not shown) is constituted by, for example, a CPU, a ROM, a RAM, and a data bus interconnecting them, and constitutes a steering control device in which the CPU performs processing described below in accordance with a program stored in the ROM.

  The EPS ECU drives and controls the motor in the automatic steering actuator 6 constituting the assist force generation EPS based on the detection result of the steering force by the steering torque sensor 5 or based on the steering command of the lane keeping assist system ECU 8. The driving force generated by the motor is transmitted to a lower shaft (not shown) via a worm wheel (not shown), and functions as a steering device that generates an assist force that assists the steering force of the driver.

  Here, the output side of the lower shaft (not shown) is drivably coupled to a pinion of a rack and pinion mechanism in the automatic steering actuator 6, and when a steering force is input to the steering wheel 1 by a driver, an assist force proportional to the steering force is obtained. Is generated in the motor under the control of the EPS ECU, and the assist force is transmitted to the pinion of the lower shaft, the intermediate shaft and the rack and pinion mechanism via the worm wheel, and the rack bar is moved in the vehicle width direction. A wheel (not shown) is steered by a tie rod connected to the outer side of the bar in the vehicle width direction to generate a steered force.

  Hereinafter, the lane keeping support system 1 will be described with reference to flowcharts. FIG. 2 is a flowchart showing the control contents of the lane keeping support system 1 according to the present invention.

  As shown in step S1 in FIG. 2, the lane keeping assist system ECU 8 positions the vehicle based on a technique such as binarization based on an image ahead of the vehicle imaged by the front lane detection camera 10. Recognize the white line on both sides of the lane, recognize the center of the lane located in the center of both white lines, detect the curvature γ and lane width of the road on which the vehicle is running, and the offset amount from the center of the lane of the vehicle, A deflection angle, that is, a yaw angle with respect to the center of the vehicle lane is detected.

  In step S2, a turning torque for maintaining the vehicle in the center of the lane is calculated based on the road shape data detected in step 1, and a turning torque command is output to the EPS ECU.

  Further, in step S3, the gear ratio changing means 8c of the lane keeping assist system ECU 8 detects the vehicle speed of the vehicle by the vehicle speed detection device 7, calculates the gear ratio of VGRS3, and outputs a gear ratio command to VGRS3. The VGRS 3 selects a gear ratio based on the gear ratio command.

  Subsequently, in step S4, the gear ratio changing means 8c of the lane keeping assist system ECU 8 determines whether or not the gear ratio of the VGRS 3 is being changed. If the result is affirmative, the process proceeds to step S5. It is determined whether or not the absolute value of the curvature γ detected in S1 is equal to or less than the predetermined threshold value 1. If the result is affirmative, the process proceeds to step S6. If the result is negative, the process proceeds to step S8.

  In step S6, the gear ratio changing means 8c of the lane keeping assist system ECU 8 outputs a command for returning the gear ratio to the normal value to the VGRS 3, and in step S7, the VGRS 3 changes the gear ratio based on the command. Return to the normal value.

  Further, in step 5, when the curvature γ is equal to or less than the predetermined threshold value 1, the VGRS 3 updates the gear ratio based on a command from the lane keeping assist system ECU8.

  In step 9, the lane keeping assist system ECU 8 determines whether or not the absolute value of the curvature γ is greater than or equal to the predetermined threshold value 2 and proceeds to step S10 if affirmative, and proceeds to step S1 if negative. Return.

  In step S10, the lane keeping assist system ECU 8 detects whether the gear ratio state of the VGRS 3 is being changed, and in step S11, changes the gear ratio so as to increase to a value larger than normal.

  According to the lane keeping support system 1 of the present embodiment executed by the control described above, when the curvature γ detected by the detecting means 8a of the lane keeping support system ECU 8 is equal to or greater than a predetermined threshold, the lane keeping support system ECU 8 The gear ratio changing means 8c increases the gear ratio obtained by dividing the input-side steering angle of the input-side column shaft 2 by the output-side steering angle of the intermediate column shaft 4 on the output side, so that the detecting means 8a If the curvature detected by the above is equal to or greater than a predetermined threshold, EPS causes unnecessary turning torque due to noise included in the curvature, and unnecessary turning due to misrecognition occurs. Since the EPS steering wheel is rotated, it is possible to allow the driver to recognize that unnecessary steering occurs at a timing earlier than in the prior art. .

  As a result, intervention steering can be executed by the driver at an earlier timing, so that the vehicle is prevented from being deflected by unnecessary steering as much as possible, unnecessary steering of the driver is reduced as much as possible, and complicated steering is performed. The operation can be omitted.

  This effect will be described in more detail with reference to the drawings. 3-5 is a schematic diagram which shows the effect which the control result of the lane maintenance assistance system 1 concerning this invention brings.

  As shown in the left side view of FIG. 3, depending on the technique for removing noise caused by erroneous detection by the prior art using a filter, the time change of the steering angle when the steering angle of the steering wheel 1 is directly calculated from the curvature γ is A The time change of the steering angle when the steering angle of the steering wheel 1 is calculated by filtering the curvature γ is as shown in B1, and the steering angle of the steering wheel 1 is directly calculated from the curvature γ. When the steering angle of the steering wheel 1 is calculated by filtering the curvature γ with respect to the temporal change A of the steering angle in this case, the phase of the steering angle temporal change B1 is delayed.

  On the other hand, as shown in the right side of FIG. 3, when the curvature γ detected by the detecting means 8a of the lane keeping assist system ECU 8 is equal to or greater than a predetermined threshold 2 as in this embodiment, the gear ratio of VGRS3, That is, when the gear ratio obtained by dividing the steering angle of the input-side column shaft 2 by the steering angle of the intermediate column shaft 4 is made larger than the normal value and the detected curvature γ is equal to or less than the predetermined threshold value 1, By returning the ratio to the normal value, the time change of the steering angle when the steering angle of the steering wheel 1 is directly calculated from the curvature γ is as shown in A, and the steering is performed by filtering the curvature γ. The time change of the steering angle when the steering angle of the wheel 1 is calculated is as shown in B2, and with respect to the time change A of the steering angle when the steering angle of the steering wheel 1 is calculated directly from the curvature γ, Book The time change B2 of the steering angle according to the embodiment is not substantially delayed in phase, and the value of the steering angle itself is made larger than normal.

  This also applies to the actual waveform of the steering angle shown in FIG. 4, and, as shown in the upper diagram of FIG. The time change of the steering angle when the steering angle of the steering wheel 1 is directly calculated from γ is as shown in A. The time of the steering angle when the steering angle of the steering wheel 1 is calculated by filtering the curvature γ. The change is as shown in B1. That is, the time of the steering angle when the steering angle of the steering wheel 1 is calculated by filtering the curvature γ with respect to the time change A of the steering angle when the steering angle of the steering wheel 1 is directly calculated from the curvature γ. The phase of the change B1 is delayed.

  On the other hand, according to the present embodiment, as shown in the lower diagram of FIG. 4, the steering angle detected by the detecting means 8 a of the lane keeping assist system ECU 8 is a value at which the curvature γ becomes a predetermined threshold value 2 or more. In this case, the gear ratio of VGRS 3, that is, the gear ratio obtained by dividing the steering angle of the input side column shaft 2 by the steering angle of the intermediate column shaft 4 is made larger than the normal value, and the detected steering angle becomes When the absolute value of the curvature γ is a value that is equal to or less than the predetermined threshold value 1, the gear ratio is returned to the normal value. Therefore, the steering angle when the steering angle of the steering wheel 1 is directly calculated from the curvature γ. The time change of the steering angle when the steering angle of the steering wheel 1 is calculated by filtering the curvature γ with respect to the time change A of the steering wheel 1 is as shown in B2, and the steering angle of the steering wheel 1 directly from the curvature γ. Calculated In this case, the phase of the steering angle time change B2 according to the present embodiment can hardly be delayed, and the value of the steering angle itself can be made larger than usual.

  As described above, according to the lane keeping assist system 1 of this embodiment, when the curvature detected by the detecting means 8a of the lane keeping assist system ECU 8 is equal to or greater than a predetermined threshold, the gear ratio of the lane keeping assist system ECU 8 is changed. The means 8c increases the gear ratio obtained by dividing the input side steering angle of the input side column shaft 2 by the output side steering angle of the intermediate column shaft 4 on the output side, so that it is detected by the detecting means 8a. When the curvature is greater than or equal to a predetermined threshold, when noise is included in the curvature, the EPS generates unnecessary turning torque and unnecessary turning due to misrecognition occurs. Since the steering wheel 1 is rotated at a timing earlier than that in the case of using it, it is possible to prevent unnecessary steering from occurring at a timing earlier than that of the prior art. It can be recognized by the driver.

  As a result, in the lane keeping support system 1 of the present embodiment, the driver can be notified of the occurrence of unnecessary steering at an earlier timing than the prior art, and intervention steering can be executed by the driver. The vehicle can be prevented from being deflected by unnecessary steering at an earlier timing, the vehicle can be prevented from being deflected as much as possible, unnecessary steering of the driver can be reduced as much as possible, and complicated steering operation can be omitted. .

  That is, in the lane keeping support system 1 of the present embodiment, in the prior art, as shown in the middle diagram in FIG. 5, the driver performs the intervention steering after the vehicle is largely deflected by noise due to misrecognition, As shown in the lower part of FIG. 5, the vehicle deflection due to noise due to erroneous recognition can be prevented in advance as the vehicle deflection is corrected. Furthermore, as shown in the upper diagram in FIG. 5, when the vehicle actually enters a curvature curve that is equal to or greater than a predetermined threshold and the driver steers, the phase of rotation of the steering angle of the steering wheel 1 advances. Since the driver can be presented as if the response to the steering of the vehicle has become faster, the driver can be given a sense of security.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions are made to the above-described embodiments without departing from the scope of the present invention. be able to.

  The lane keeping support system according to the present invention can be applied to any of the column assist type, pinion assist type, and rack assist type, and can also be applied to a type having a hydraulic booster.

  The present invention relates to a lane keeping support system for a vehicle, and can provide a lane keeping support system that does not cause a complicated steering operation with a relatively simple gear structure and minor changes. It is useful when applied to various vehicles such as passenger cars, trucks, and buses.

It is a mimetic diagram showing one embodiment of a lane maintenance support system concerning the present invention. It is a flowchart which shows the control content of one Embodiment of the lane maintenance assistance system concerning this invention. It is a schematic diagram which shows the effect of one Embodiment of the lane maintenance assistance system concerning this invention. It is a schematic diagram which shows the effect of one Embodiment of the lane maintenance assistance system concerning this invention. It is a schematic diagram which shows the effect of one Embodiment of the lane maintenance assistance system concerning this invention.

Explanation of symbols

1 Lane maintenance support system 2 Input side column shaft 3 VGRS
4 Intermediate column shaft 5 Steering torque sensor 6 Automatic steering actuator 7 Vehicle speed detection device 8 Lane maintenance support system ECU
8a Detection means 8b Lane keeping means 8c Gear ratio changing means 9 Direction indicator 10 Front lane detection camera

Claims (2)

  Imaging means for imaging the front of the vehicle, detection means for detecting the offset distance and deflection angle of the vehicle with respect to the center of the lane ahead of the vehicle, and the curvature of the center of the lane from the front image captured by the imaging means Lane maintaining means for outputting a steering command to a steering control device for controlling the steering device of the vehicle so as to maintain the vehicle at the center of the lane based on the offset distance, the deflection angle, and the curvature, and The steering device includes a steering angle variable mechanism that varies a gear ratio obtained by dividing the input-side steering angle of the input-side drive shaft by the output-side steering angle of the output-side drive shaft, and includes the curvature detected by the detection means. A lane keeping support system comprising gear ratio changing means for changing the gear ratio based on the gear ratio.   2. The lane keeping assist system according to claim 1, wherein the gear ratio changing unit increases the gear ratio when the curvature is equal to or greater than a predetermined threshold value.

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