JP2010125952A - Lane keeping or lane departure prevention system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep a current running lane by suppressing departure of a vehicle from the running lane while securing a stable vehicle behavior. <P>SOLUTION: A system includes: an electric power-steering device 110 including a steering angle ratio variable mechanism 113 assisting the steering of a steering wheel 3 with a motor 4 and changing a steering angle ratio of turning angles of front wheels 1L, 1R relative to a steering angle of the steering wheel 3; tow angle changing devices 120L, 120R making tow angles of rear wheels 2L, 2R changeable; and a steering control ECU 130 determining a deviation from a target which is set when keeping a running lane; and based on a determination result of the steering control ECU 130, controls the steering angle ratio of the steering angle ratio variable mechanism 113 and the tow angles of the rear wheels 2L, 2R. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle lane keeping or lane departure prevention system.

  For example, when there is no preceding vehicle as a vehicle driving support means for supporting a vehicle that travels while detecting the external environment of the vehicle with a CCD camera, a radar device, etc., while maintaining a constant distance from the preceding vehicle Is an ACC system (adaptive cruise control system) that travels at a constant speed, a lane keeping system that operates the steering wheel so that it does not deviate from the traveling lane in which the vehicle travels, and the distance between the vehicle and the preceding vehicle is less than a predetermined value A collision mitigation brake system that automatically decelerates and stops when an obstacle is detected or when an obstacle is detected is known.

  For example, in Patent Document 1, in a lane keeping system, a boundary line such as a white line provided on a road surface of a traveling lane is identified by performing image processing on a video obtained by capturing a traveling lane in a traveling direction with a CCD camera, And the technique which steers so that a motor vehicle may not deviate from a boundary line by steering operation of a front wheel is disclosed.

Patent Document 2 discloses an all-wheel independent steering device that independently controls the operation of all traveling wheels based on the operation angle of the steering wheel and the vehicle speed.
JP 2006-44563 A Japanese Examined Patent Publication No. 6-47388

  By the way, in the lane keeping system according to the prior art, in steering the vehicle, the front wheels use an electric power steering device so that the vehicle does not deviate from the boundary line by increasing an operation reaction force applied to the steering handle, or The collision with the obstacle is avoided by assisting the steering of the steering wheel so that the vehicle returns to the own lane.

  In this case, in the lane keeping system according to the prior art, the lane keeping control of the vehicle is performed only by the electric power steering device, and the change amount of the yaw rate due to the operation of the steering handle is not controlled as it is, and the steering is The required amount of operation of the handle is also kept constant without being changed. For this reason, when the driver operates the steering wheel in order to keep the lane due to a change in the yaw rate or the like, the vehicle behavior may become unstable.

  The present invention has been made in view of the above points, and can prevent lane keeping or lane departure that can suppress (prevent) lane departure and keep lane while ensuring stable vehicle behavior. The purpose is to provide a system.

  In order to achieve the above object, the present invention assists steering by a steering wheel that steers front wheels with an electric motor, and changes the steering angle ratio of the steering angle of the wheel to the steering angle of the steering handle. An electric power steering device having a variable ratio mechanism, a toe angle changing device capable of changing the toe angles of the left and right rear wheels, a determination device for determining a deviation from a target set when keeping the driving lane; And a steering control device for controlling the steering angle ratio variable mechanism and the toe angle changing device of the electric power steering device based on a determination result of the determination device.

  According to the present invention, when the determination device determines that there is a possibility of a collision because the vehicle departs from the traveling lane and there is an obstacle (an oncoming vehicle) in the deviating direction, or the vehicle moves through the traveling lane. When it is determined that the vehicle has deviated, the steering control device is provided to the driver who operates the steering handle by controlling the electric power steering device when the driver tries to operate the vehicle in the departure direction. In addition, the control signal is derived for the steering angle ratio variable mechanism, and the vehicle deviates from the driving lane by the steering angle ratio of the steering angle of the wheel (front wheel) to the steering wheel operating angle. Reduce compared to before. At the same time, the steering control device derives a control signal so that the toe angle of the rear wheel becomes toe-in at a predetermined angle, and operates the toe angle changing device to change the toe angle of the rear wheel to toe-in.

  By such control, a driver who operates the steering wheel is given a feeling of steering operation that makes the steering wheel heavy, and the steering angle ratio is reduced by a predetermined value compared to before the departure of the driving lane. By doing so, the amount of operation required by the steering wheel is increased by a predetermined amount, and the amount of load applied to the steering wheel is increased.

  As a result, in the present invention, the steering operation by the steering wheel becomes insensitive (dull) characteristics, the driver is prompted to perform the steering operation to avoid the deviation and return the steering wheel, and the vehicle deviates from the driving lane. As compared with the front, the actual steering angle of the front wheels is controlled not to increase corresponding to the steering operation angle even if the steering wheel is turned by a predetermined angle. In addition, by setting the toe angle of the rear wheels to toe-in, the generation of the yaw rate is suppressed and the stability of the vehicle behavior can be maintained.

  As described above, in the present invention, when the determination device determines that there is a possibility of a collision because the vehicle departs from the traveling lane and there is an obstacle (an oncoming vehicle) in the deviating direction, or deviates from the traveling lane. When it is determined that the vehicle behavior control by the steering angle ratio of the electric power steering device and the steering angle ratio variable mechanism and the vehicle behavior control by the toe angle changing device are performed substantially simultaneously, while ensuring the stability of the vehicle behavior, Lane departure or lane departure prevention can be prevented by suppressing deviation from the running lane.

  Further, according to the present invention, the steering control device increases an operation reaction force applied to a driver who operates the steering handle, and the vehicle deviates from the traveling lane with respect to the steering angle ratio of the steering angle ratio variable mechanism. By deactivating the toe angle changing device and changing the toe angle of the rear wheels to toe-in, the deviation from the driving lane is suppressed while ensuring the stability of the vehicle behavior. You can keep the lane.

  Further, in the present invention, when the driver tries to operate the vehicle in the direction of reducing deviation, the steering control device drives the electric motor provided in the electric power steering device and operates the steering handle. The steering angle ratio of the variable steering angle ratio mechanism is increased compared to before the collision avoidance operation is started, and the toe angle changing device is operated. It is preferable to configure the rear wheel toe angle to be changed to toe-out.

  That is, after the determination device determines that the vehicle has deviated from the driving lane, when the vehicle is about to collide with an obstacle such as an oncoming vehicle, the steering control device drives the electric motor of the electric power steering device and moves the steering handle. The driver assists the driver to actively avoid a collision, increases the rudder angle ratio of the rudder angle ratio variable mechanism as compared with that before the collision avoidance operation, and increases the rear wheel toe angle. The toe angle changing device is operated so that is toe out at a predetermined angle.

  Therefore, according to the present invention, the driver who operates the steering handle in order to avoid a collision with an obstacle (oncoming vehicle) assists the steering with the driving force of the electric motor so that the steering handle can be easily cut, and By increasing the angle ratio by a predetermined value as compared with before the collision avoidance operation, the necessary operation amount of the steering wheel can be increased at an early stage, and the steering wheel turning delay operation can be avoided. In addition, the rear wheel toe angle is set to toe-out, and the generation of yaw rate is promoted. By using the generated yaw rate, the vehicle is quickly retracted to avoid collision with an obstacle (oncoming vehicle) at an early stage. can do.

  Furthermore, in the present invention, in the steering control device, when the vehicle avoids a collision or returns to an appropriate position in the traveling lane, the driver operating the steering by the electric motor provided in the electric power steering device is provided. The steering assist operation for actively avoiding the collision is stopped to return the load on the driver to the state before the collision avoidance operation is started, and the steering angle ratio of the rudder angle ratio variable mechanism is changed to before the collision avoidance operation is started. It is preferable that the rear wheel toe angle is returned to the state before the collision avoiding operation is started.

  That is, when it is determined by the determination device that the vehicle (own vehicle) has deviated from the travel lane and returned to the collision avoidance position or an appropriate position in the travel lane, the electric motor of the electric power steering device is brought into a state before the start of the collision avoidance operation. The steering assist for actively avoiding the collision is stopped for the driver who operates the steering wheel, and the operation is returned to the state before the collision avoidance operation is started. By returning to this state, it is possible to return to the state before the start of the collision avoidance operation in which the steering load is reduced from the state in which the steering assist is activated.

  Therefore, the driver can confirm that the vehicle has moved to the collision avoidance position by experiencing such a reduction in the steering load. As a result, it is possible to prevent the driver from making the vehicle's behavior unstable by performing an unnecessary avoidance operation, and to easily return from the avoidance behavior by steering to the normal driving mode.

  It is possible to obtain a lane keeping or lane departure preventing system capable of suppressing (preventing) a departure from a traveling lane and keeping a lane while ensuring stability of vehicle behavior.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. FIG. 1 is an overall conceptual diagram of a four-wheel vehicle to which a vehicle system according to an embodiment of the present invention is applied, and FIG. 2 is a configuration diagram of an electric power steering device that constitutes the steering system.

As shown in FIG. 1, the vehicle system 100 includes an electric power steering device 110 that assists the steering by the steering handle 3 that steers the front wheels 1L and 1R with the electric motor 4, the operation angle of the steering handle 3, and the vehicle speed. Steering control devices 130 (hereinafter referred to as steering control) for controlling the toe angle changing devices 120L and 120R, the electric power steering device 110, and the toe angle changing devices 120L and 120R that change the toe angles of the rear wheels 2L and 2R independently by the actuator 30. ECU), an image processing device 150 that processes image information for lane keeping, a vehicle speed sensor S _V , a yaw rate sensor _{SY, and the} like.

  The left and right front wheels 1L and 1R are steered wheels that determine the traveling direction of the vehicle V provided with the vehicle system 100, and the driver steers the front wheels 1L and 1R by operating the steering handle 3 to move the vehicle V in the left-right direction. Turn to.

Yaw rate sensor S _Y is a sensor for detecting a yaw rate generated in the vehicle V. This yaw rate sensor _SY is, for example, “0” when no yaw rate is generated in the vehicle V, a positive value when a left yaw rate is generated, and a right yaw rate being generated. A negative value is output at.

(Electric power steering device)
As shown in FIG. 2, the electric power steering device 110 (hereinafter, also referred to as EPS as necessary) has a steering handle 3, which has an operation angle detection sensor 111 and a shaft via a shaft. The operation reaction force motor 112 is connected. The operation reaction force motor 112 is connected to the steering control ECU 130 via a drive circuit (not shown), and an appropriate operation reaction force is applied to the driver when driven. The operation reaction force motor 112 may be omitted, and the operation reaction force may be applied to the steering handle 3 by the electric motor 4 described later.

  That is, the operation reaction force motor 112 receives a signal from the steering control ECU 130 and corresponds to an operation angle and an operation direction of the steering handle 3 and has a direction different from the operation direction of the steering handle 3 (movement of the steering handle 3). In addition, by generating a reaction force (operation reaction force) of a predetermined magnitude, the operability and accuracy of the steering operation are improved.

  The electric power steering device 110 also has a variable steering angle ratio that appropriately changes the steering angle ratio of the steering angle of the wheel (front wheel) to the operation angle of the steering handle 3 rotated by the driver's operation in accordance with the vehicle speed or the like. A mechanism 113 is included. The rudder angle ratio variable mechanism 113 is composed of a wave gear reducer such as a known harmonic drive (registered trademark). Thus, the steering system having the steering angle ratio variable mechanism 113 controls the front wheels 1L, 1R by AFS (Active Front Steering) by changing the steering angle ratio. Note that the steering angle ratio may be controlled by using a steer-by-wire in which mechanical connection between the steering handle 3 and the steering system is cut off, and using a steering angle sensor (not shown).

  As shown in FIG. 2, a pinion shaft 7 is provided below the rudder angle ratio variable mechanism 113 so as to extend. A pinion gear 7 a provided at the lower end of the pinion shaft 7 meshes with rack teeth 8 a of a rack shaft that can reciprocate in the vehicle width direction. The front wheels 1L and 1R are connected. With this configuration, the electric power steering apparatus 110 can change the traveling direction of the vehicle when the steering handle 3 is operated. The pinion shaft 7 is supported by the steering gear box 6 via a bearing (not shown).

  The electric power steering device 110 includes an electric motor 4 that supplies an auxiliary steering force for reducing the steering force by the steering handle 3, and a worm gear 5 a provided on the output shaft of the electric motor 4 is connected to the pinion shaft 7. Is engaged with a worm wheel gear 5b provided in That is, the speed reduction mechanism is configured by the worm gear 5a and the worm wheel gear 5b.

  The electric motor 4 includes a three-phase brushless motor including a stator (not shown) having a plurality of field coils and a rotor (not shown) that rotates inside the stator, and converts electric energy into mechanical energy. Is.

The electric power steering apparatus 110 includes a motor drive circuit 23 for driving the electric motor 4, a resolver 25 for detecting the rotation angle of the electric motor 4, a torque sensor S _T for detecting the pinion torque applied to the pinion shaft 7, torque a differential amplifier circuit 21 for amplifying an output of the sensor S _T, and a vehicle speed sensor S _V for detecting the speed of the vehicle (vehicle speed).

  The electric motor drive circuit 23 includes a plurality of switching elements such as a three-phase FET bridge circuit, for example, generates a rectangular wave voltage using a DUTY (DU, DV, DW) signal from the steering control ECU 130, and 4 is driven. The motor drive circuit 23 also has a function of detecting a three-phase motor current using a hall element (not shown).

The operation angle detection sensor 111 detects the operation amount of the steering handle 3, and is configured by, for example, a potentiometer, and outputs the operation angle of the steering handle 3 as a voltage value. Further, the torque sensor _ST is constituted by, for example, a strain gauge or the like, and detects the amount of torque input from the steering handle 3. Further, the vehicle speed sensor S _V is for detecting the vehicle speed VS of the vehicle V as a pulse number per unit time, and outputs a vehicle speed signal VS.

(Toe angle changing device)
Next, the configuration of the toe angle changing devices 120L and 120R will be described with reference to FIGS. FIG. 3 is a plan view of the toe angle changing device on the left rear wheel side, and FIG. 4 is a schematic cross-sectional view showing the structure of the actuator of the toe angle changing device.

  The toe angle changing devices 120L and 120R (hereinafter also referred to as RTC as needed) are respectively attached to the left and right rear wheels 2L and 2R of the vehicle V. In FIG. 3, the left rear wheel 2L is taken as an example. A toe angle changing device 120L is shown. The toe angle changing device 120L includes an actuator 30 and a toe angle changing control device (hereinafter referred to as a toe angle changing control ECU) 37. Note that FIG. 3 shows only the left rear wheel 2L, but the right rear wheel 2R is also attached in the same manner (symmetrical).

  As shown in FIG. 3, the vehicle width direction end of the cross member 12 extending substantially in the vehicle width direction is elastically supported by the rear side frame 11 of the vehicle body. The front end of the trailing arm 13 extending substantially in the longitudinal direction of the vehicle body is supported in the vicinity of the end of the cross member 12 in the vehicle width direction. A rear wheel 2L is fixed to the trailing end of the trailing arm 13. In the trailing arm 13, a vehicle body side arm 13 a attached to the cross member 12 and a wheel side arm 13 b fixed to the rear wheel 2 </ b> L are connected via a rotation shaft 13 c in a substantially vertical direction. Thereby, the trailing arm 13 can be displaced in the vehicle width direction.

  One end of the actuator 30 is attached to the front end of the wheel side arm 13b in front of the rotation shaft 13c via the ball joint 16, and the other end is attached to the cross member 12 via another ball joint 17. Yes.

  As shown in FIG. 4, the actuator 30 includes an electric motor 31, a speed reduction mechanism 33, a feed screw portion 35, and the like. The electric motor 31 is configured by a brush motor, a brushless motor, or the like that can rotate in both forward and reverse directions. The speed reduction mechanism 33 is configured by combining, for example, a two-stage planetary gear (not shown).

  The feed screw portion 35 meshes with a rod 35a formed in a cylindrical shape, a nut 35c inserted into the rod 35a to have a cylindrical shape, and a screw groove 35b formed on the inner peripheral side, and the screw groove 35b. The screw shaft 35d supports the rod 35a so as to be displaceable in the axial direction.

  The feed screw portion 35 is accommodated in an elongated, substantially cylindrical case body 34 together with the speed reduction mechanism 33 and the electric motor 31. Further, a resin or rubber boot 36 is attached to the feed screw 35 side of the case main body 34 so as to cover the end of the case main body 34 and the end of the rod 35a. The boot 36 can prevent dust and foreign matter from adhering to the outer peripheral surface of the rod 35 a exposed from the end of the case main body 34, and prevent dust and foreign matter from entering the case main body 34 from the outside.

  One end of the speed reduction mechanism 33 is coaxially connected to the output shaft of the electric motor 31, and the other end is connected to the screw shaft 35d. The rotational driving force from the electric motor 31 is transmitted to the screw shaft 35d via the speed reduction mechanism 33, and the screw shaft 35d rotates, so that the rod 35d can move forward and backward in the left-right direction (axial direction) with respect to the case body 34. It is supposed to work. The toe angles of the rear wheels 2L and 2R are kept constant even when the motor 31 is not energized and driven by the frictional force of engagement between the screw shaft 35d and the screw groove 35b of the nut 35c.

  Further, the actuator 30 is provided with a stroke sensor 38 for detecting the position of the rod 35a (the amount of displacement at the time of forward / backward movement). The stroke sensor 38 has a built-in magnet, for example, and can detect the position using magnetism. Thus, by detecting the position using the stroke sensor 38, the steering angles (toe angles) of the toe-in and toe-out of the rear wheels 2L and 2R can be detected individually with high accuracy.

  In the actuator 30 configured in this manner, the ball joint 16 provided at the distal end of the rod 35a is rotatably connected to the wheel side arm 13b (see FIG. 3) of the trailing arm 13, and the base end of the case main body 34 is connected. A ball joint 17 provided at a portion (the right end in FIG. 4) is rotatably connected to the cross member 12 (see FIG. 3). When the screw shaft 35d rotates by the rotational driving force of the electric motor 31 and the rod 35a extends in the left direction in FIG. 4, the wheel side arm 13b is pressed outward in the vehicle width direction (left direction in FIG. 3), and the rear wheel 2L. Turns to the left. On the other hand, when the rod 35a retracts in the right direction in FIG. 4, the wheel side arm 13b is pulled inward in the vehicle width direction (right direction in FIG. 3), and the rear wheel 2L turns in the right direction.

  The part to which the ball joint 16 of the actuator 30 is attached is not limited to the wheel side arm 13b as long as it is a position where the toe angle of the rear wheel 2L such as a knuckle can be changed. In the present embodiment, the case where the toe angle changing devices 120L and 120R are applied to a semi-trailing arm type independent suspension type suspension is illustrated, but the present invention is not limited to this. The actuator may be assembled to a side rod of a suspension or a side rod of a strut suspension.

  Further, a toe angle change control ECU 37 is integrally attached to the actuator 30. The toe angle change control ECU 37 is fixed to the case body 34 of the actuator 30 and is connected to the stroke sensor 38 via a connector or the like. Further, the left and right toe angle change control ECUs 37 and 37 and the toe angle change control ECUs 37 and 37 and the steering control ECU 130 are connected by a communication line. The toe angle changing control ECU 37 is supplied with electric power from a power source such as a battery (not shown) mounted on the vehicle. Electric power is also supplied to the steering control ECU 130 and the motor drive circuit 23 from a power source such as a battery in a separate system.

(Toe angle change control ECU)
Next, a detailed configuration of the toe angle change control ECU will be described with reference to FIG. FIG. 5 is a block diagram of the toe angle change control ECU.
As shown in FIG. 5, the toe angle change control ECU 37 has a function of driving and controlling the actuator 30, that is, the electric motor 31, and is configured by a control unit 81 and an electric motor drive circuit 83. Each toe angle change control ECU 37 is connected to the steering control ECU 130 via a communication line, and one and the other toe angle change control ECUs 37 are connected via a communication line (see FIGS. 1 and 5). ing. In this case, the steering control ECU 130 and the toe angle change control ECU 37 constitute a steering control device.

  The control unit 81 includes a microcomputer having a CPU, RAM, ROM, and the like, peripheral circuits, and the like, and includes a target current calculation unit 81a, an electric motor control signal generation unit 81c, and a self-diagnosis unit 81d.

  On the other hand (to the right rear wheel 2R side), the target current calculation unit 81a of the toe angle change control ECU 37 includes a vehicle speed, an operation angle, and a target toe angle of the rear wheel 2R input from the steering control ECU 130 via a communication line. Based on the current toe angle of the rear wheel 2R obtained from the stroke sensor 38, a target current signal is calculated and output to the motor control signal generator 81c.

  The target current calculation unit 81a of the other (left rear wheel 2L side) toe angle change control ECU 37 includes a vehicle speed input from the steering control ECU 130 via a communication line, an operation angle, a target toe angle of the rear wheel 2L, Based on the current toe angle of the rear wheel 2L obtained from the stroke sensor 38, a target current signal is calculated and output to the motor control signal generator 81c. Here, the target current signal is a current signal necessary for setting the actuator 30 at a desired speed to a desired operation amount (a displacement amount with the rear wheels 2L, 2R as a desired toe angle).

  The motor control signal generator 81 c receives the target current signal from the target current calculator 81 a and outputs a motor control signal to the motor drive circuit 83. The electric motor control signal includes a signal including a current value supplied to the electric motor 31 and a direction in which the current flows. The motor drive circuit 83 is configured by a FET (Field Effect Transistor) bridge circuit or the like, and supplies a motor current to the motor 31 based on a motor control signal.

  Further, as shown in FIG. 5, the self-diagnosis unit 81d receives the position information from the stroke sensor 38, the signal of the state of the motor drive circuit 83, and the target current signal from the target current calculation unit 81a. It is checked whether an abnormality detection signal is received from the other toe angle change control ECU 37 to which No belongs. That is, a signal indicating whether or not the electric motor 31 and the electric motor drive circuit 83 corresponding to its own toe angle change control ECU 37 are operating properly is received and monitored, and the other toe angle change control ECU 37 is supported. A signal indicating whether or not the motor 31 and the motor drive circuit 83 to be operated are operating soundly is monitored.

(Image processing device)
Next, returning to FIG. 1, the image processing apparatus 150 will be described. This image processing apparatus 150 is an apparatus that captures and processes image data of a traveling lane in which the vehicle V travels, and identifies a boundary line formed by a center line or a white line (including a yellow line) provided on the road surface of the traveling lane. The CCD camera 151 that captures the traveling lane in the traveling direction and the image processing unit 152 are configured. Then, the video signal captured by the CCD camera 151 is subjected to image processing by the image processing unit 152 to extract a boundary line such as a center line or a white line provided on the road surface of the traveling lane, and the traveling lane state in the traveling direction (for example, Curve curvature, etc.).

Further, the image processing apparatus 150 uses the relationship between the extracted boundary line and the traveling position of the vehicle V as a target for setting the center position of the vehicle V and the traveling lane at the time of lane keeping, deviation between the center of the traffic lane x (hereinafter, referred to as lateral displacement x), calculates a yaw angle phi _V of the vehicle V with respect to the boundary line has a function of notifying to the steering control ECU 130.

  Further, the image processing device 150 performs image processing on the video signal captured by the CCD camera 151 by the image processing unit 152, for example, when an obstacle such as an oncoming vehicle is detected outside the boundary line, the steering control ECU 130 It has a function to notify.

  Here, for example, the image processing apparatus 150 sets the lateral displacement x to “0” when the vehicle V travels the center position of the travel lane, and the vehicle V deviates from the center position of the travel lane. Outputs the deviation (distance) from the center position of the travel lane. For example, if the vehicle V is configured to output a positive value when the vehicle V shifts to the left from the center position of the travel lane and outputs a negative value when the vehicle V shifts to the right, the amount and direction of the shift Can be output.

  The method by which the image processing apparatus 150 extracts a boundary line such as a center line or a white line is not particularly limited. For example, the input image is binarized, and the road surface and the center are calculated based on the brightness difference. This can be realized by a method for identifying lines, white lines, and the like. Further, the CCD camera 151 provided in the image processing apparatus 150 is not limited to this, and for example, a complementary metal oxide semiconductor (CMOS) camera or the like is preferably used.

(Steering control ECU)
The steering control ECU 130 (see FIG. 1) is connected to the motor drive circuit 23 (see FIG. 2) of the electric power steering device 110 and the left and right toe angle changing devices 120L and 120R, and controls each of them and is connected to each sensor. A device for inputting information output from each sensor. Further, the steering control ECU130 is connected to the image processing apparatus 150, information such as the yaw angle phi _V and lateral displacement x of the vehicle V with respect to the boundary line is input from the image processing apparatus 150. The steering control ECU 130 includes a microcomputer including a CPU, a ROM, a RAM, and the like (not shown) and peripheral circuits.

Further, the steering control ECU130, the horizontal displacement x that is input from the vehicle speed VS and the image processing apparatus 150 of the vehicle V, based on the yaw angle phi _V of the vehicle V with respect to the boundary line, the target is set required lane keeping .

(Lane Keep)
A vehicle V (see FIG. 1) including the vehicle system 100 including the above components extracts a boundary line such as a center line or a white line provided on the road surface of the travel lane by the image processing device 150, and travels. The vehicle travels while detecting the lateral displacement x (deviation from the target) of the vehicle V with respect to the center position of the lane.

Then, the steering control ECU 130 receives the lateral displacement x of the vehicle V with respect to the center position of the traveling lane and the vehicle V with respect to the boundary line, which are input from the image processing device 150 so that the vehicle V does not deviate from the traveling lane. based on the yaw angle phi _V information such as the controls toe angle changer 120 and an electric power steering apparatus 110.

  FIG. 6 is a schematic block diagram relating to lane keep control. Hereinafter, the lane keeping control will be described with reference to FIG.

First, with respect to the steering control ECU 130, the image processing apparatus 150 lateral displacement x, such as the yaw angle phi _V information, the torque signal from the torque sensor _{S T,} vehicle speed signal from a vehicle speed sensor _{S V,} from the yaw rate sensor _{S Y} Each yaw rate signal is input. It is assumed that the toe angles of the left and right rear wheels 2L, 2R are initialized in advance to the initial state.

  The steering control ECU 130 determines whether or not the vehicle V deviates from a boundary line such as a center line or a white line provided in the traveling lane based on these signals and the like, and the vehicle V deviates from the boundary line. If it is determined, the deviation reduction control is instructed. Note that the “departure” to be determined includes not only that a part of the vehicle V deviates from the boundary line of the traveling lane but also that the vehicle is largely deviated from the center of the traveling lane.

  That is, the steering control ECU 130 outputs a control signal to the operation reaction force motor 112 of the electric power steering apparatus 110 (hereinafter also referred to as EPS if necessary) to drive the operation reaction force motor 112, thereby steering the steering handle. 3 is increased, and a control signal is output to the rudder angle ratio variable mechanism 113, and the wheels (front wheels 1L, 1R) with respect to the rudder angle (operating angle) of the steering handle 3 are increased. ) AFS control is performed to lower (reduce) the steering angle ratio with respect to the steering angle of the vehicle V compared to before the vehicle V deviates from the travel lane (see FIG. 6A).

  The EPS steering control gives the driver operating the steering handle 3 a feeling of steering operation that makes the steering handle 3 heavy, and compares the steering angle ratio with that before the departure of the driving lane by AFS control. As a result, the required amount of operation by the steering handle 3 is increased by a predetermined amount, and the amount of load applied to the steering handle 3 is increased.

  As a result, the steering operation by the steering handle 3 becomes insensitive (dull) characteristics, and the driver is urged to perform the steering operation to return the steering handle 3 while avoiding the departure, and the steering handle is compared with that during normal driving. Control is performed so that the actual turning angle of the front wheels 1L and 1R does not increase corresponding to the steering operation angle even if 3 is turned by a predetermined angle. In other words, even when the driver turns the steering wheel 3, the actual turning angle of the front wheels 1L, 1R is controlled so as not to increase corresponding to the operating angle of the steering wheel 3.

  At the same time, the steering control ECU 130 derives a control signal from the toe angle changing control ECU 37 so that the toe angles of the left and right rear wheels 2L, 2R become “toe-in” at a predetermined angle, and operates the toe angle changing device 120. And change the toe angle to “Toe-in”. The toe angle change control ECU 37 sets the left and right rear wheels 2L, 2R to “toe-in” having a desired toe angle by driving the electric motor 31 of the actuator 30 to retract the rod 35a along the axial direction. Can do. Note that the toe angles of the left and right rear wheels 2L, 2R are detected by a stroke sensor 38, and feedback controlled based on the detection signal. In this case, by setting the toe angles of the left and right rear wheels 2L and 2R to “toe-in”, the generation of the yaw rate is suppressed and the stability of the vehicle behavior can be maintained.

  Thus, in the present embodiment, when the steering control ECU 130 determines that the vehicle has deviated from the boundary line, when the driver tries to operate the vehicle V in the deviating direction, the steering control by EPS and AFS, and the RTC By performing the vehicle behavior control by the substantially simultaneously, it is possible to keep the lane while suppressing the deviation from the traveling lane while ensuring the stability of the vehicle behavior.

  Next, after it is determined that the steering control ECU 130 has deviated from the boundary line, for example, control when it is likely to collide with an obstacle such as an oncoming vehicle will be described below.

  After the steering control ECU 130 determines that the vehicle has deviated from the boundary line, the image processing apparatus 150 detects an obstacle such as an oncoming vehicle and the vehicle V is about to collide with the oncoming vehicle. When operating in the direction of deviation reduction, the steering control ECU 130 instructs collision avoidance assist control.

  That is, the steering control ECU 130 derives a control signal for the electric motor drive circuit 23 of the EPS to drive the electric motor 4 and to assist the driver who operates the steering handle 3 to actively avoid a collision. In addition, a control signal is derived for the steering angle ratio variable mechanism 113, and the steering angle ratio of the steering angle of the wheel (front wheel) to the steering angle (operation angle) of the steering handle 3 is determined before the collision avoiding operation. AFS control that is increased (increased) as compared with (see FIG. 6B).

  By the steering control by the EPS, the steering assist is performed by the driving force of the electric motor 4 so that the driver operating the steering handle 3 can easily turn the steering handle 3 to avoid a collision with an obstacle (oncoming vehicle). At the same time, the AFS control increases (increases) the steering angle ratio by a predetermined value compared to before the collision avoidance operation, thereby increasing the required amount of operation at an early stage and avoiding the delayed turning operation of the steering handle 3.

  As a result, the steering operation by the steering wheel 3 becomes sensitive, and the steering operation is performed so that the driver quickly turns the steering wheel 3 in order to avoid a collision with an obstacle (an oncoming vehicle) early. At the same time, it is controlled so that the actual turning angle of the front wheels 1L, 1R is increased even if the steering handle 3 is slightly turned compared to the normal driving. In other words, even if the driver slightly turns the steering handle 3, the actual turning angle of the front wheels 1L, 1R is controlled to be larger than the turning angle corresponding to the operation angle of the steering handle 3.

  At the same time, the steering control ECU 130 derives a control signal from the toe angle change control ECU 37 so that the toe angles of the left and right rear wheels 2L, 2R become “toe out” at a predetermined angle. The toe angle change control ECU 37 sets the left and right rear wheels 2L, 2R to “toe out” having a desired toe angle by driving the electric motor 31 of the actuator 30 and extending the rod 35a along the axial direction. Can do. Note that the toe angles of the left and right rear wheels 2L, 2R are detected by a stroke sensor 38, and feedback controlled based on the detection signal. In this case, by setting the toe angles of the left and right rear wheels 2L, 2R to “toe out”, the generation of the yaw rate is promoted, and the vehicle V is quickly retracted using the generated yaw rate, A collision with an obstacle (an oncoming vehicle) can be avoided at an early stage. In the AFS control, when the operation amount of the steering wheel 3 is increased to the required operation amount due to the steering angle ratio raised by the steering angle variable mechanism 113, the steering angle ratio is lowered to a predetermined value.

  As described above, in the present embodiment, in the departure prevention control, the steering load is promoted and the steering handle 3 becomes heavy, and the change in the yaw rate is suppressed, so that the stability of the vehicle behavior can be ensured. Further, in the present embodiment, in the collision avoidance assist control, the driver's steering delay of the steering wheel 3 is suppressed, and a yaw rate change is generated early, thereby avoiding a collision with an obstacle (an oncoming vehicle) at an early stage. Can do.

  Further, in the present embodiment, when the steering control ECU 130 determines that the vehicle V (own vehicle) has deviated from the travel lane and returned to the collision avoidance position or an appropriate position in the travel lane, the electric motor 4 of the electric power steering apparatus 110 is used. Alternatively, the operation reaction force motor 112 is returned to the state before the start of the collision avoidance operation, and the operation of the steering assist for actively avoiding the collision with respect to the driver who operates the steering handle 3 is stopped before the start of the collision avoidance operation. By returning to this state and returning the steering angle ratio of the steering angle ratio variable mechanism 113 to the normal state, it is possible to return from the state in which the steering assist is activated to the state before the start of the collision avoidance operation in which the steering load is reduced.

  Therefore, the driver can confirm that the vehicle V has moved to the collision avoidance position by experiencing such a reduction in the steering load. As a result, it is possible to prevent the driver from performing the avoidance operation more than necessary to make the behavior of the vehicle V unstable, and to easily return from the avoidance behavior due to steering to the normal driving mode.

1 is an overall conceptual diagram of a four-wheel vehicle to which a vehicle system according to an embodiment of the present invention is applied. It is a block diagram of the electric power steering apparatus which comprises the said vehicle system. It is a block diagram of the toe angle changing device on the left rear wheel side constituting the vehicle system. It is a schematic sectional drawing which shows the structure of the actuator of the said toe angle change apparatus. It is a block diagram of toe angle change control ECU which comprises the said vehicle system. (A), (b) is a schematic block diagram regarding lane keep control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Steering handle 4 Electric motor 23 Electric motor drive circuit 37 Toe angle change control ECU (steering control apparatus)
DESCRIPTION OF SYMBOLS 110 Electric power steering apparatus 113 Steering angle ratio variable mechanism 120R, 120L Toe angle change apparatus 130 Steering control ECU (steering control apparatus, determination apparatus)

Claims (4)

An electric power steering device having a steering angle ratio variable mechanism that assists steering by a steering wheel that steers front wheels with an electric motor, and changes a steering angle ratio of a steering angle of a wheel to an operation angle of the steering handle;
A toe angle changing device capable of changing the toe angles of the left and right rear wheels;
A determination device for determining a deviation from a target set when keeping the driving lane;
A steering control device for controlling the steering angle ratio variable mechanism and the toe angle changing device of the electric power steering device based on the determination result of the determination device;
A lane keep or lane departure prevention system comprising: The lane keep or lane departure prevention system according to claim 1,
The steering control device increases an operation reaction force applied to a driver who operates the steering handle, and compares the steering angle ratio of the steering angle ratio variable mechanism with that before the vehicle deviates from the travel lane. And a lane keeping or lane departure prevention system, wherein the toe angle changing device is operated to change the toe angle of the rear wheels to toe-in. The lane keep or lane departure prevention system according to claim 1,
The steering control device drives a motor provided in the electric power steering device to assist a driver who operates a steering handle to actively avoid a collision, and to change the steering angle ratio. A lane keep or a steering angle ratio of the mechanism is increased as compared with that before the collision avoidance operation is started, and the toe angle changing device is operated to change the toe angle of the rear wheel to toe out. Lane departure prevention system. The lane keep or lane departure prevention system according to claim 3,
The steering control device actively responds to a driver who operates the steering by an electric motor provided in the electric power steering device when the own vehicle avoids a collision or returns to an appropriate position in a traveling lane. The operation of the steering assist for avoiding the collision is stopped to return the load on the driver to the state before the start of the collision avoidance operation, and the steering angle ratio of the steering angle ratio variable mechanism is set to the state before the start of the collision avoidance operation. A lane keep or lane departure prevention system that returns and returns the toe angle of the rear wheel by the toe angle changing device to the state before the start of the collision avoidance operation.

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