JP2008201311A - Lane maintenance support device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lane maintenance assist device capable of reducing the risk of inducing a driver into a comfortable snoozing state, and preventing any lane deviation of one's own vehicle. <P>SOLUTION: When the vigilance of a driver D is degraded, the supporting torque is given to a steering mechanism so that one's own vehicle 101 makes a meandering motion in a lane 103. The travel in the lane 103 is maintained without any risk by avoiding any contact with other vehicle or the like, and the risk of inducing the driver in a comfortable snoozing state is reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lane keeping assist device.

2. Description of the Related Art Conventionally, a vehicle travel control device that detects a travel position of a host vehicle and performs lane tracking travel control (steering control) that applies auxiliary steering torque based on the detected travel position (for example, is known) , See Patent Document 1). The lane tracking travel control device described in Patent Document 1 includes steering torque detection means, and when the detected steering torque is greater than or equal to a predetermined determination threshold value, the driver determines that the driver is intervening in steering, and performs steering. It has a function to release control. Further, the lane tracking travel control device includes a look-a-side detection unit that detects the driver's look-aside. When the driver's look-aside is detected, it is difficult to cancel the steering control by setting a determination threshold value larger than normal. In addition, the wobbling of the host vehicle is prevented by increasing the applied assist steering torque.
Japanese Patent Laid-Open No. 2002-362391

  However, in the conventional technique, when the driver's side aside is detected, the steering assist torque is increased to prevent the vehicle from wobbling, so this technique is applied as it is when the driver's arousal level is low. In such a case, the driver's consciousness may be lowered, and a comfortable sleep may be induced.

  The present invention has been made to solve such a problem, and reduces the risk of inducing the driver to a comfortable dozing state and prevents a lane departure of the host vehicle. The purpose is to provide.

  The lane keeping assist device according to the present invention is a lane keeping assist device provided with a control means for applying an assist torque to the steering mechanism so as to travel in a predetermined position in the lane. The control means reduces the driver's arousal level. In this case, the auxiliary torque is controlled so that the vehicle runs meandering.

  According to such a lane keeping assist device, when the driver's arousal level is low, the assist torque can be applied to the steering mechanism so that the host vehicle meanders in the lane. Thereby, while avoiding contact with other vehicles etc., without being accompanied by a danger, while maintaining driving | running | working in a lane, the possibility of inviting a driver | operator to a comfortable doze state is reduced. The `` wakefulness level '' indicates the level of the driver's drowsiness. For example, if the driver is not asleep and can perform normal driving operations, the level of wakefulness is high. If the driver is in a dozing state and his / her concentration is reduced and normal driving operation cannot be performed, “the degree of arousal is low”.

  A steering torque detecting means for detecting the steering torque; and a control stopping means for stopping the application of the auxiliary torque by the control means when the steering torque detected by the steering torque detecting means is equal to or greater than a predetermined determination threshold. In addition, when the driver's arousal level is low, it is preferable to set the predetermined determination threshold value larger than when the driver's awakening level is not low. As a result, when the driver's arousal level is reduced, the determination threshold is set larger than when the driver's arousal level is not decreased. Therefore, it is difficult to stop the application of the auxiliary torque by the control means. Become. Therefore, when the arousal level is lowered, the auxiliary torque is surely applied by the control means. Further, it is preferable that the control means controls the auxiliary torque so that the own vehicle meanders irregularly when the driver's arousal level is lowered.

  ADVANTAGE OF THE INVENTION According to this invention, while reducing the possibility of inducing a driver | operator to a comfortable dozing state, the lane maintenance assistance apparatus which aimed at prevention of the lane departure of the own vehicle can be provided.

  A preferred embodiment of a lane keeping assist device according to the present invention will be described below with reference to the drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted. FIG. 1 is a system configuration diagram showing a lane keeping assist device 100 according to an embodiment of the present invention.

  1 recognizes a travel lane (lane) 103 on which the host vehicle 101 (see FIG. 3) travels, and based on the position of the travel lane 103 and the host vehicle 101, the host vehicle 101 It is determined whether or not the vehicle departs from the travel lane 103, and when it is determined that the host vehicle 101 departs, a steering assist torque is applied to perform lane keeping support. In other words, the lane keeping assist device 100 controls the steering assist torque applied to the steering mechanism, and performs travel support so that the host vehicle 101 travels in the vicinity of the center 104 of the travel lane. The lane keeping assist device 100 includes a lane keeping assist electronic control unit (hereinafter referred to as “lane keeping assist ECU”) 1, which includes a CPU that performs arithmetic processing, ROM and RAM serving as a storage unit, An input signal circuit, an output signal circuit, a power supply circuit, and the like are included.

  The lane keeping assist device 100 includes a face image capturing camera 2 that captures a face image of the driver D, and a face image processing electronic control unit (hereinafter referred to as “face image” that performs image processing based on a video signal from the face image capturing camera 2. Processing ECU ”) 3, a vehicle front image capturing camera 4 that acquires an image ahead of the vehicle, a front image processing electronic control unit (hereinafter referred to as“ front image processing ”) that performs image processing based on a video signal from the vehicle front image capturing camera 4 ECU ”5), a vehicle speed sensor 6 for detecting the vehicle speed, and a steering torque sensor 7 for detecting the steering torque. Output signals from these face image processing ECU 3, front image processing ECU 5, vehicle speed sensor 6, and steering torque sensor 7 are input to the lane keeping assist ECU 1. Further, an alarm device 8 that outputs an alarm sound is electrically connected to the lane keeping assist ECU 1.

  A lane keeping switch 12 is electrically connected to the lane keeping assist ECU 1. The lane keep switch 12 is a switch for selecting activation (ON) and stop (OFF) of the lane keeping assist device 100 by an operation by the driver D. The lane lane keep switch 12 transmits ON / OFF information selected by the driver to the lane keeping assist ECU 1 as a switch signal.

  The lane keeping assist device 100 includes a steering electronic control unit (hereinafter referred to as “steering ECU”) 10 that controls the steering torque. The steering ECU 10 includes a CPU that performs arithmetic processing, a ROM and a RAM that are storage units, an input signal circuit, an output signal circuit, a power supply circuit, and the like. The steering ECU 10 is electrically connected to the lane keeping assist ECU 1, the steering torque sensor 7, and the steering actuator 11. The steering ECU 10 receives signals from the lane keeping assist ECU 1 and the steering torque sensor 7, calculates a steering assist torque to be applied to the steering actuator 11, and controls the steering actuator 11. The steering actuator 11 has, for example, an electric motor, and applies steering assist torque to a steering shaft (not shown).

  The face image capturing camera 2 is installed, for example, on the upper surface of the column cover 9 and acquires the face image of the driver D. The face image processing ECU 3 functions as wakefulness determination means that performs image processing based on the input video signal, recognizes the face image of the driver D, and determines the wakefulness level of the driver D. This face image processing ECU 3 detects the closed state of the driver D based on the face image of the driver D, and determines that the awakening level of the driver D is lowered when the driver D is closed. The awakening degree determination means may determine the face angle of the driver D and determine that the awakening degree is low when the driver D is facing downward.

  The vehicle front image pickup camera 4 is arranged at the front center of the vehicle 101 of the vehicle 101 and acquires an image of the road surface in front of the vehicle through the windshield. The forward image processing ECU 5 performs image processing based on the input video signal, and road marking lines that divide both ends of the traveling lane 103 in which the host vehicle 101 is traveling (white lines, yellow lines drawn on the road, Although there are cases where the blocks are arranged or embedded on the road, they are hereinafter referred to as “white lines”.) 102 is detected, and the travel lane 103 on which the host vehicle 101 travels is recognized.

  The lane keeping assist ECU 1 predicts the future travel locus of the host vehicle 101 based on the output signals from the front image processing ECU 5, the vehicle speed sensor 6, and the steering torque 7, and the white line position recognized by the front image processing ECU 5. To determine whether or not the host vehicle 101 departs from the travel lane 103.

  Further, the lane keeping assist ECU 1 transmits an output signal to the steering ECU 10 when it is determined that the host vehicle deviates from the traveling lane, and the steering ECU 10 drives the steering actuator 11 to apply the steering assist torque. Can do.

  The lane keeping assist ECU 1 functions as a control stopping unit that stops (suspends) the application of the steering assist torque when the steering torque detected by the steering torque sensor 7 is equal to or greater than a predetermined determination threshold Q. Note that the “predetermined determination threshold value” is a determination reference value for determining whether or not the driver is performing a steering operation with his / her own intention. When the steering torque detected by the steering torque sensor 7 is equal to or greater than the predetermined determination threshold Q, the application of the steering assist torque is stopped, while the steering torque detected by the steering torque sensor 7 is the predetermined determination threshold Q. If not, the steering assist torque can be applied.

  Here, the lane keeping assist ECU 1 applies steering assist torque so that the host vehicle 101 meanders in the travel lane 103 when the awakening degree determination unit determines that the awakening degree of the driver D is lowered. can do.

  Further, the lane keeping assist ECU 1 determines that the awakening level of the driver D does not decrease the “predetermined determination threshold” when the awakening level determination unit determines that the awakening level of the driver D is decreased. Set larger than the case. As a result, when the driver's D awakening level is reduced, it becomes difficult to stop the application of the steering assist torque.

  The ROM of the steering ECU 10 stores data (map) for setting the steering assist torque in addition to the program for operating the CPU. Next, an example of setting of the steering assist torque will be described with reference to FIG. FIG. 2 is a graph showing a setting example of the steering assist torque. In FIG. 2, the vertical axis indicates the magnitude of the steering assist torque applied, and the horizontal axis indicates the lateral position of the host vehicle 101 in the travel lane 103. The magnitude of the steering assist torque shown on the vertical axis is zero at the center in the vertical direction, “+” (upper side in the figure) is the steering assist torque for steering the host vehicle in the left direction, and “−”. (Lower side in the figure) is a steering assist torque for steering the host vehicle in the right direction.

  In FIG. 2, L1 indicated by a solid line is an example of setting of the steering assist torque in the normal time. When the awakening level of the driver D is not lowered, the steering control at the normal time is executed, and the steering assist torque indicated by L1 is applied. For example, when the host vehicle 101 is traveling in the center of the travel lane 104, the steering assist torque is not applied, and when the host vehicle 101 is traveling on the right side of the center of the travel lane 104, the leftward direction. When the own vehicle 101 is traveling on the left side of the traveling lane center 104, the steering assist torque in the right direction is applied. Specifically, when the host vehicle 101 is traveling on the right side of the travel lane center 104 and does not exceed the point P1, the steering assist torque in the left direction increases in proportion to the distance from the travel lane center 104. When the host vehicle 101 travels outside the point P1, the steering assist torque has a constant value. When the host vehicle 101 is traveling on the left side of the travel lane center 104 and does not exceed the point P2, the steering assist torque in the right direction increases in proportion to the distance from the travel lane center 104, and the host vehicle 101 Is traveling outside the point P2, the steering assist torque has a constant value.

  In FIG. 2, L2 indicated by a broken line and L3 indicated by a solid line are setting examples of the steering assist torque when the arousal level is lowered. When the awakening level of the driver D is lowered, steering control corresponding to the lowered awakening level is executed, for example, the steering assist torque indicated by L2 is first applied, and then the steering assist torque indicated by L3 is applied. Thereafter, the steering assist torque indicated by L2 and the steering assist torque indicated by L3 are alternately applied. When the host vehicle 101 approaches the white line 102, steering assist torque is applied so as not to exceed the white line 102.

  In L2, when the host vehicle 101 is traveling at the point P3 located on the left side of the travel lane center 104, the steering assist torque is not applied, and the host vehicle 101 is traveling in the travel lane center 104. Is given a steering assist torque in the left direction. Specifically, when the host vehicle 101 is traveling on the right side of the point P3 and does not exceed the point P4, the steering assist torque in the left direction increases in proportion to the distance from the point P3. When 101 runs outside the point P4, the steering assist torque has a constant value. When the host vehicle 101 is traveling on the left side of P3 and does not exceed the point P5, the steering assist torque in the right direction increases in proportion to the distance from the point P3, and the host vehicle 101 is outside the point P5. When traveling, the steering assist torque has a constant value.

  In L3, when the host vehicle 101 is traveling at the point P6 located on the right side of the travel lane center 104, the steering assist torque is not applied, and when the host vehicle 101 is traveling in the travel lane center 104. Is given a steering assist torque in the left direction. Specifically, when the host vehicle 101 is traveling on the right side of the point P6 and does not exceed the point P7, the steering assist torque in the right direction increases in proportion to the distance from the point P6. When 101 runs outside the point P7, the steering assist torque has a constant value. When the host vehicle 101 is traveling on the left side of P6 and does not exceed the point P8, the steering assist torque in the left direction increases in proportion to the distance from the point P6, and the host vehicle 101 is outside the point P8. When traveling, the steering assist torque has a constant value.

  Thus, the host vehicle 101 can be meandered by alternately selecting L2 and L3. In addition, by preparing a plurality of types of other steering assist torque setting patterns and irregularly selecting a plurality of types of steering assist torque setting patterns, a steering assist torque that causes the host vehicle 101 to meander irregularly is provided. Can be granted.

  In the steering control corresponding to the awakening level decrease, it is not necessary to alternately apply the steering assist torque indicated by L2 and the steering assist torque indicated by L3. For example, after applying the steering assist torque indicated by L2 a plurality of times, L3 A steering assist torque indicated by

  Next, an example of the travel locus of the host vehicle 101 meandering by steering control corresponding to a decrease in arousal level will be described with reference to FIG. FIG. 3 is a plan view showing an example of a traveling locus of the host vehicle that is meandering with the steering assist torque applied when the arousal level is lowered. As shown in FIG. 3, when it is determined that the awakening level of the driver D is lowered, the host vehicle 101 is applied with a steering assist torque and controlled to meander. When the host vehicle 101 approaches the white line 102, steering assist torque in the opposite direction of the white line 102 is applied, and the host vehicle 101 meanders in the travel lane 103.

  Next, a control process executed by the lane keeping assist ECU 1 will be described along the flowchart of FIG. FIG. 4 is a flowchart showing a procedure of control processing executed by the lane keeping assist ECU 1. First, the lane keeping assist ECU 1 determines whether or not the lane keeping assist system (LKA system) is being activated based on, for example, a switch signal from the lane keep switch 12 (S1). If it is determined that the LKA system is being activated, the process proceeds to step 2. If it is not determined that the LKA system is being activated, the process is terminated.

  In step 2, the lane keeping assist ECU 1 calculates a steering torque based on a signal from the steering torque sensor 7, and determines whether or not the steering torque is equal to or greater than a predetermined determination threshold Q (initial value q1). If it is determined that the steering torque is equal to or greater than the predetermined determination threshold Q, the process proceeds to step 3 where the application of the steering assist torque is stopped (control is interrupted), and the process ends. On the other hand, if it is not determined that the steering assist torque is equal to or greater than the predetermined determination threshold Q, the process proceeds to step 4.

  In step 4, the lane keeping assist ECU 1 determines whether or not the driver D's arousal level is reduced based on a signal from the face image processing ECU 3. When it is determined that the awakening level of the driver D is lowered, an alarm sound is output (S5), and the process proceeds to Step 6. On the other hand, if it is not determined that the awakening level of the driver D has decreased, the process proceeds to step 7.

  In step 6, the lane keeping assist ECU 1 sets q1 to a predetermined determination threshold value Q and proceeds to step 8. In step 7, the lane keeping assist ECU 1 sets q2 (q1> q2) as a predetermined determination threshold value Q, and proceeds to step 9. As described above, when the arousal level is lowered, the predetermined determination threshold Q is set larger than that when the awakening level is not lowered.

  In step 8 and step 9, the lane keeping assist ECU 1 refers to the map (FIG. 2) stored in the storage unit and executes control (S 8) and normal control (S 9) corresponding to when the arousal level is reduced. Exit. The host vehicle 101 is controlled to meander in the travel lane 103 when the control corresponding to the decrease in the arousal level is executed. In addition, when the normal control is executed, the host vehicle 101 is controlled to travel in the vicinity of the traveling lane center 104.

  According to such a lane keeping assist device 100, when the driver's D awakening level is lowered, the steering assist torque is applied to the steering mechanism so that the host vehicle 101 meanders in the travel lane 103. The driver D is not invited to a comfortable dozing state. Further, since the host vehicle 101 meanders in the travel lane 103, contact with other vehicles can be avoided, and lane keeping support can be provided without danger, and the lane departure of the host vehicle 101 can be prevented. be able to. In addition, since the host vehicle 101 meanders in the travel lane 103, it is easy for the surroundings to recognize that the host vehicle 101 is dozing (abnormal state).

  Further, the lane keeping assist device 100 can cancel the lane keeping assist system and stop applying the steering assist torque when the steering torque detected by the steering torque sensor 7 is equal to or greater than a predetermined determination threshold Q. . In addition, when the arousal level is low, the predetermined determination threshold Q is set to be larger than that when the awakening level is not low. Auxiliary torque can be applied.

  As mentioned above, although this invention was concretely demonstrated based on the embodiment, this invention is not limited to the said embodiment. In the above embodiment, the “predetermined determination threshold” is set to be larger when the driver's arousal level is lower than when the driver's arousal level is not decreased. May be a constant value.

  Moreover, in the said embodiment, although the steering assist torque provided to a steering mechanism is set based on the map shown in FIG. 2, the setting of a steering assist torque is not limited to this, For example, the own vehicle 101 When traveling along the traveling lane center 104, the steering assist torque in the right direction may be applied, or the steering assist torque may not be applied. In short, when the driver's arousal level is low, the steering assist torque may be applied so that the host vehicle meanders, and the meandering may be either regular or irregular.

  Further, in the above embodiment, when the driver D is closed, it is determined that the awakening level of the driver D is reduced. However, the awakening level of the driver D is determined by other methods. Also good. For example, the face direction angle of the driver D may be calculated, and when the driver D is facing downward, it may be determined that the awakening level of the driver D has decreased. In addition, for example, the degree of arousal may be determined using biological information such as a driver's blood pressure and brain waves.

  Further, the lane keeping assist device 100 may be a lane keeping assist device provided with an aside look determining means for judging a driver's look aside.

1 is a system configuration diagram illustrating a lane keeping assist device according to an embodiment of the present invention. It is a graph which shows the example of a setting of steering assistance torque. It is a top view which shows an example of the driving | running | working locus | trajectory of the own vehicle to which a steering assistance torque is given at the time of awakening fall and to meander. It is a flowchart which shows the procedure of the control processing performed by lane keeping assistance ECU which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Lane maintenance assistance ECU (control means, control stop means), 3 ... Face image processing ECU (wakefulness determination means), 7 ... Steering torque sensor, 10 ... Steering ECU (control means, control stop means), 100 ... Lane Maintenance support device, 101 ... host vehicle, 103 ... driving lane (lane), 104 ... center of driving lane.

Claims (3)

In the lane keeping assist device provided with a control means for applying an auxiliary torque to the steering mechanism so as to travel a predetermined position in the lane,
The control means controls the auxiliary torque so that the host vehicle meanders when the driver's arousal level is lowered. Steering torque detection means for detecting steering torque;
Control stopping means for stopping application of auxiliary torque by the control means when the steering torque detected by the steering torque detecting means is equal to or greater than a predetermined determination threshold,
2. The lane according to claim 1, wherein when the driver's arousal level is reduced, the predetermined determination threshold is set to be larger than that when the driver's awakening level is not decreased. Maintenance support device.   The lane keeping assist device according to claim 1 or 2, wherein the control means controls the auxiliary torque so that the own vehicle meanders irregularly when the driver's arousal level is lowered. .

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