JP2008137612A - Steering support device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering support device which enables a driver to appropriately trace a traveling lane without making a driver feel uncomfortable. <P>SOLUTION: The steering support device 1 is provided with a steering angle sensor 23 for detecting a steering angle θ of a steering wheel 14, wheel speed sensors 12FR to 12RL for detecting vehicle speed VC, and a VGRS ECU 40 for calculating a target variable turning angle of a turning angle variable device 24 based on the steering angle θ and vehicle speed VC. The steering support device 1 is further provided with an image processing device 41 for detecting a yaw angle of the vehicle V with respect to the vehicle lane. When calculating the target variable turning angle, the VGRS ECU 40 increases correction amount (steering support variable turning angle) for correcting the target variable turning angle as the yaw angle increases. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steering assist device.

Japanese Patent Application Laid-Open No. 2004-133867 discloses a technique for assisting a steering force so that a target travel line is set in accordance with the travel state of the vehicle and the vehicle travel line is matched with the set target travel line.
JP-A-11-105728

  The technique described in Patent Document 1 does not realize complete automatic driving (automatic running), but only supports the steering of the driver. For example, when turning a curve, the driver's steering is required. At this time, if there is a deviation between the above-described target travel line and the driver's intention, the driver may feel uncomfortable.

  On the other hand, when the speed of the vehicle increases, the response of the vehicle to steering changes. However, it is not always easy for a driver who is not used to high-speed driving to take into account this change in response. For this reason, for example, on an expressway curve, it is not possible to perform appropriate steering corresponding to the curve at a time, so that a situation may occur in which the steering wheel is repeatedly switched back and forth.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a steering assist device capable of appropriately tracing a traveling lane without causing a driver to feel uncomfortable. .

  The steering assist device according to the present invention is based on a steering state detection unit that detects a steering state of a steering wheel, a traveling state detection unit that detects a traveling state of the vehicle, a steering state of the steering wheel, and a traveling state of the vehicle, A steering support apparatus including a control unit that calculates a steering support control amount of the steering wheel includes a behavior state detection unit that detects a behavior state of the vehicle with respect to the traveling lane, and the control unit is configured to calculate the steering support control amount. The steering assist control amount is corrected based on the behavior state of the vehicle.

  According to the steering assist device of the present invention, when the steering assist control amount is calculated based on the steering state (for example, the steering angle) of the steering wheel by the driver and the traveling state (for example, the vehicle speed) of the vehicle, the result of the steering is calculated. The steering assist control amount is corrected based on the behavior state of the vehicle with respect to the travel lane (travel lane) that appears as Therefore, it is possible to set the steering assist control amount so that the steering characteristic is suitable for the traveling lane while the steering based on the driver's intention is taken as a basis. As a result, it is possible to appropriately trace the traveling lane without causing the driver to feel uncomfortable.

  Here, the behavior state of the vehicle is a yaw angle of the vehicle, and it is preferable that the control unit increases the correction amount for correcting the steering assist control amount as the yaw angle increases.

  The yaw angle of the vehicle is an angle formed by the longitudinal axis of the vehicle and a tangent to the travel lane, and indicates the relative direction of the vehicle with respect to the travel lane. be able to. Here, according to the steering assist device according to the present invention, the greater the yaw angle of the vehicle, that is, the more the steering wheel is cut or the more the steering wheel is cut, the more the steering assist control amount is corrected. Therefore, the steering assist control amount can be corrected so that the steering characteristic is suitable for the traveling lane.

  The steering assist device according to the present invention preferably includes steering speed detection means for detecting the steering speed of the steering wheel, and the control means preferably decreases the correction amount as the steering speed increases.

  In this way, since excessive turning of the steering wheel is suppressed, an excessive increase in steering response can be suppressed. As a result, the traveling lane can be traced more easily.

  Further, the steering assist device according to the present invention includes a steering speed detecting means for detecting a steering speed of the steering wheel, and a reference steering speed calculating means for calculating a reference steering speed according to the turning radius of the traveling lane, and a control means. However, it is preferable to change the correction amount in accordance with the magnitude relationship between the actual steering speed detected by the steering speed detecting means and the reference steering speed.

  In this way, for example, when the actual steering speed is higher than the reference steering speed according to the turning radius of the traveling lane, it is determined that the driver's steering speed is too high and the steering wheel is switched back. The correction amount can be changed. As a result, it is possible to perform steering support so as to reduce the meandering traveling.

  In the steering assist device according to the present invention, it is preferable that the control means decreases the correction value as the steering angle decreases in a region where the steering angle of the steering wheel is equal to or less than a predetermined steering angle.

  By providing a dead zone corresponding to the play of the steering wheel in this way, it is possible to suppress hunting of the correction amount for turning on / off the steering and to reduce the uncomfortable feeling at the time of control intervention. Further, in this case, since the correction amount is set for the main steering by the driver, it is possible to prevent excessive interference in steering assistance.

  In the steering assist device according to the present invention, it is preferable that the control means decreases the correction value as the vehicle speed increases in a region where the vehicle speed of the vehicle is equal to or higher than a predetermined vehicle speed.

  The movement of the vehicle with respect to steering becomes more rapid as the speed increases. According to the steering assist device of the present invention, the correction value decreases as the vehicle speed increases in a high-speed region that is equal to or higher than a predetermined vehicle speed, so that it is possible to compensate for vehicle characteristics that change depending on the vehicle speed.

  Here, the steering assist control amount is preferably a target variable turning angle of the turning angle variable control for changing the steering gear ratio.

  According to the present invention, when the steering assist control amount is calculated according to the steering state of the steering wheel and the traveling state of the vehicle, the steering assist control amount is corrected based on the behavior state of the vehicle with respect to the traveling lane. Thus, it is possible to appropriately trace the traveling lane without causing the driver to feel uncomfortable.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted.

  First, the configuration of the steering assist device 1 will be described with reference to FIG. 1, taking as an example the case where the steering assist device 1 according to the first embodiment is mounted on the vehicle V. FIG. 1 is a block diagram for explaining the configuration of the steering assist device 1.

  The vehicle V includes a right front wheel 10FR, a left front wheel 10FL, a right rear wheel 10RR, and a left rear wheel 10RL. The wheels 10FR to 10RL include wheel speed sensors 12FR, 12FL, 12RR, 12RL for detecting the wheel speed (hereinafter, the four wheel speed sensors 12FR, 12FL, 12RR, 12RL may be collectively referred to as the wheel speed sensor 12). Is attached. Wheel speed sensors 12FR to 12RL are connected to a variable gear ratio control electronic control unit (hereinafter referred to as "VGRS ECU") 40, and wheel speed signals detected by wheel speed sensors 12FR to 12RL are output to VGRS ECU 40. . In the present embodiment, the wheel speed (that is, the vehicle speed) corresponds to the traveling state of the vehicle described in the claims, and the wheel speed sensor 12 corresponds to the traveling state detecting means.

  The right front wheel 10FR and the left front wheel 10FL are steered wheels, and are steered via a rack bar 18 and tie rods 20L and 20R by a rack and pinion type power steering device 16 driven in response to an operation of the steering wheel 14. Is done.

  The power steering device 16 is, for example, a rack coaxial type electric power steering device, and includes an electric motor 17 and a ball screw type conversion mechanism 19 that converts the rotational torque of the electric motor 17 into a force in the reciprocating direction of the rack bar 18. And an auxiliary steering force that drives the rack bar 18 relative to the housing 21 is generated.

  The steering wheel 14 is connected to the pinion shaft 30 via an upper steering shaft 22, a turning angle variable device (VGRS) 24, a lower steering shaft 26, and a universal joint 28. The turning angle varying device 24 is connected to the lower end of the upper steering shaft 22 on the housing 24A side. On the other hand, the rotor 24 </ b> B of the electric motor 32 for driving auxiliary steering that constitutes the turning angle varying device 24 is connected to the upper end of the lower steering shaft 26.

  The turning angle varying device 24 drives the lower steering shaft 26 to rotate relative to the upper steering shaft 22, whereby the ratio of the turning angle of the left front wheel 10 FL and the right front wheel 10 FR to the rotation angle of the steering wheel 14, that is, Change the steering gear ratio. The turning angle varying device 24 is controlled by the VGRS ECU 40.

  The turning angle varying device 24 is adapted to the upper steering shaft 22 by the electric motor 32 so that the steering gear ratio becomes a gear ratio that achieves a predetermined steering characteristic during auxiliary turning driving by lane keeping assistance (steering assistance) control. By relatively rotating the lower steering shaft 26 and automatically turning the left front wheel 10FL and the right front wheel 10FR, it is possible to appropriately trace the travel lane while reducing the amount of steering operation by the driver. Provide steering assistance.

  The upper steering shaft 22 is provided with a steering angle sensor 23 that detects the rotation angle of the upper steering shaft 22 (that is, the steering angle of the steering wheel 14). The turning angle varying device 24 is provided with a rotation angle sensor 25 that detects the relative rotation angle of the housing 24A and the rotor 24B as the relative rotation angle of the lower steering shaft 26 with respect to the upper steering shaft 22. The steering angle sensor 23 and the rotation angle sensor 25 are connected to the VGRS ECU 40, and detection signals from both sensors are output to the VGRS ECU 40. In the present embodiment, the steering angle of the steering wheel 14 corresponds to the steering state of the steering wheel described in the claims, and the steering angle sensor 23 corresponds to the steering state detection means.

  Connected to the VGRS ECU 40 is an image processing device 41 having a camera as an imaging means for capturing an image of a landscape in front of the vehicle and acquiring image data. This camera is, for example, a CCD camera, and is installed facing the front in the upper part of the front window of the vehicle (for example, the back side of the rearview mirror). The camera captures a landscape in front of the vehicle and acquires image data.

  The image processing device 41 performs image processing, arithmetic processing, and the like on the image data acquired by the camera, so that the yaw angle θ with respect to the traveling lane of the vehicle V, the turning radius R of the traveling lane, and the lane center of the vehicle V Road parameters such as lateral displacement D from the vehicle are obtained (see FIG. 2). That is, the image processing device 41 functions as a behavior state detection unit that detects the behavior state (yaw angle) of the vehicle V with respect to the traveling lane. In the present specification, as shown in FIG. 2, the yaw angle θ takes a positive value when the longitudinal axis of the vehicle is in the counterclockwise direction with respect to the tangent line of the traveling lane. Therefore, when the longitudinal axis of the vehicle is in the clockwise direction with respect to the tangent line of the traveling lane, the yaw angle θ takes a negative value.

  The VGRS ECU 40 and the image processing device 41 are configured to be able to exchange data with each other by being connected through a communication line such as a CAN (Controller Area Network). Information such as the yaw angle θ and the turning radius R obtained by the image processing device 41 is transmitted to the VGRS ECU 40 via this communication line.

  The VGRS ECU 40 includes a microprocessor that performs calculations, a ROM that stores a program for causing the microprocessor to execute each process, a RAM that stores various data such as calculation results, and a battery, and the storage contents thereof are retained. A backup RAM or the like.

  With such hardware, the VGRS ECU 40 can calculate and set the vehicle speed variable turning angle (basic variable turning angle) from the steering angle MA and the vehicle speed VC, the vehicle speed variable turning angle calculation unit 42, the yaw angle θ, the steering. A steering assist variable turning angle setting unit 44 that calculates and sets a steering assist variable turning angle (correction amount) from the angle MA, the steering angular velocity MAdot obtained by differentiating the steering angle MA, and the vehicle speed VC, and the vehicle speed variable rotation The target variable turning angle is calculated by adding the vehicle speed variable turning angle obtained by the rudder angle calculation unit 42 and the steering assistance variable turning angle obtained by the steering assistance variable turning angle setting unit 44 and calculating the target variable turning angle. A variable turning angle calculation / output unit 49 that generates a control signal according to the target variable turning angle and outputs the control signal to the turning angle variable device 24 is constructed. That is, the VGRS ECU 40 functions as the control means described in the claims. Further, the target variable turning angle corresponds to the steering support control amount described in the claims, and the steering support variable turning angle corresponds to the correction amount described in the claims.

  Further, the steering assist variable turning angle setting unit 44 is a VGRS addition angle acquisition unit 45 for obtaining a VGRS addition angle σ from the yaw angle θ and the steering angular velocity MAdot, and a turning angle gain setting for obtaining the turning angle gain GA from the steering angle MA. Unit 46, a vehicle speed gain setting unit 47 for obtaining vehicle speed gain GV from vehicle speed VC, and a multiplication unit 48 for multiplying VGRS addition angle σ, turning angle gain GA, and vehicle speed gain GV to calculate a steering assist variable turning angle. have.

  The VGRS ECU 40 controls the turning angle variable device 24 so that the relative rotation angle of the lower steering shaft 26 with respect to the upper steering shaft 22 matches the target variable turning angle. Therefore, the lower steering shaft 26 is cut by an angle obtained by adding the target variable turning angle to the steering angle by the driver's steering. As a result, the left and right front wheels 10FL and 10FR are steered so that the steering characteristics are suitable for the traveling lane, based on the driver's steering operation.

  Next, the operation of the steering assist device 1 will be described with reference to FIGS. FIG. 3 is a flowchart showing a processing procedure of steering support control by the steering support device 1. This process is executed by the VGRS ECU 40 and is repeatedly executed at a predetermined timing from when the power of the VGRS ECU 40 is turned on to when it is turned off.

  In step S100, the yaw angle θ with respect to the travel lane of the vehicle V and the turning radius R of the travel lane detected by the image processing device 41 are read.

  In the subsequent step S102, the steering angle MA of the steering wheel 14 detected by the steering angle sensor 23 and the vehicle speed VC obtained from the detection result of the wheel speed sensor 12 are read.

  In step S104, a target variable turning angle is obtained. Next, how to obtain the target variable turning angle will be described in detail with reference to FIG.

  In the VGRS ECU 40, first, the vehicle speed variable turning angle calculation unit 42 calculates the vehicle speed variable turning angle (basic variable turning angle) from the steering angle MA and the vehicle speed VC. Here, the steering gear ratio is first obtained. The vehicle speed variable turning angle calculation unit 42 is provided with a two-dimensional map (steering gear ratio map) that defines the relationship between the vehicle speed VC and the steering gear ratio. Steering is performed based on the vehicle speed VC read in step S102. The steering gear ratio is obtained by searching the gear ratio map.

  In the steering gear ratio map, as shown in FIG. 4, the steering gear ratio gradually increases from 13.5 to 20, for example, as the vehicle speed VC (km / h) increases, that is, gradually changes from quick to slow. Is set to In this steering gear ratio map, when the vehicle speed is VCt, the steering gear ratio is set to be a base gear ratio (a gear ratio that is mechanically determined when the turning angle varying device 24 is not provided, for example, 16). Has been.

  By setting the steering gear ratio map so that the steering gear ratio increases as the vehicle speed VC increases, the gear ratio is made quicker in the low speed region and the handling load is reduced. Steering is realized, and the gear ratio is made slow in the high speed region, and the vehicle characteristics are changed in a stable direction.

  Subsequently, the vehicle speed variable turning angle calculation unit 42 calculates the speed increase ratio from the obtained steering gear ratio. That is, a value obtained by subtracting 1 from the value obtained by dividing the base gear ratio by the steering gear ratio is obtained as the speed increasing ratio. Here, when the steering gear ratio is smaller than the base gear ratio, that is, when it is quick, the speed increasing ratio takes a positive (+) value, and when the steering gear ratio is larger than the base gear ratio, that is, when it is slow, the speed increasing ratio is Takes a negative (-) value.

  Then, the steering angle MA read in step S102 is multiplied by the speed increase ratio to obtain a vehicle speed variable turning angle. Here, when the speed increase ratio is a positive value, the vehicle speed variable turning angle also becomes a positive value, and the turning angle varying device 24 is driven in a direction to increase with respect to the steering by the driver. On the other hand, when the speed increase ratio is a negative value, the vehicle speed variable turning angle also becomes a negative value, and the turning angle varying device 24 is driven in a direction to switch back to the steering by the driver. The obtained vehicle speed variable turning angle is output to the variable turning angle calculation / output unit 49.

  On the other hand, the steering assistance variable turning angle setting unit 44 sets the steering assistance variable turning angle (correction amount) from the yaw angle θ, the steering angle MA, the steering angular velocity MAdot obtained by differentiating the steering angle MA, and the vehicle speed VC. Is done. As described above, the steering assist variable turning angle setting unit 44 includes the VGRS addition angle acquisition unit 45 for obtaining the VGRS addition angle σ from the yaw angle θ and the steering angular velocity MAdot, and the turning for obtaining the turning angle gain GA from the steering angle MA. Steering angle gain setting unit 46, vehicle speed gain setting unit 47 for obtaining vehicle speed gain GV from vehicle speed VC, VGRS addition angle σ, steering angle gain GA, and vehicle speed gain GV are multiplied to calculate the steering assist variable turning angle. And a multiplication unit 48.

  First, in the VGRS addition angle acquisition unit 45, the VGRS addition angle σ is acquired from the yaw angle θ and the steering angular velocity MAdot. The VGRS addition angle acquisition unit 45 is provided with a three-dimensional map (VGRS addition angle map) that defines the relationship among the yaw angle θ, the steering angular velocity MAdot, and the VGRS addition angle σ, and the yaw angle read in step S100 The VGRS addition angle σ is obtained by searching the VGRS addition angle map based on θ and the steering angular velocity MAdot obtained from the steering angle MA read in step S102. The acquired VGRS addition angle σ is output to the multiplication unit 48.

  As shown in FIG. 5, the VGRS addition angle map is set so that the VGRS addition angle σ is zero in the region where the yaw angle θ is 0 to θdz. In a region where the yaw angle θ is greater than or equal to θdz, the VGRS addition angle σ is set to increase as the yaw angle θ increases. Further, in the region where the yaw angle θ is equal to or greater than θdz, the rising slope of the VGRS addition angle σ is set to be steeper as the steering angular velocity MAdot becomes smaller, as shown by the one-dot chain line in FIG. As shown by a broken line in FIG. 5, the rising slope of the VGRS addition angle σ is set to be gentle as the steering angular velocity MAdot increases.

  FIG. 5 shows a VGRS addition angle map when the yaw angle θ takes a positive value. When the yaw angle θ takes a negative value, the absolute value of the VGRS addition angle σ is equal to that when the yaw angle θ takes a positive value, and the sign is negative.

  Subsequently, the turning angle gain setting unit 46 sets the turning angle gain GA from the steering angle MA. The turning angle gain setting unit 46 includes a two-dimensional map (steering angle gain map) that defines the relationship between the steering angle MA and the turning angle gain GA, and the steering angle MA read in step S102. The turning angle gain GA is set by searching the turning angle gain map based on the above. The set turning angle gain GA is output to the multiplication unit 48.

  As shown in FIG. 6, the turning angle gain map is such that the turning angle gain GA increases from 0 to 1.0 as the steering angle MA increases in the region where the steering angle MA is 0 to MAdz. Is set to In other words, as the steering angle MA decreases, the turning angle gain GA decreases from 1.0 to 0. Further, in a region where the steering angle MA is equal to or greater than MAdz, the turning angle gain GA is set to 1.0.

Next, the vehicle speed gain setting unit 47 sets the vehicle speed gain GV from the vehicle speed VC.
The vehicle speed gain setting unit 47 is provided with a two-dimensional map (vehicle speed gain map) that defines the relationship between the vehicle speed VC and the vehicle speed gain GV. The vehicle speed gain map is searched based on the vehicle speed VC read in step S102. As a result, the vehicle speed gain GV is set. The set vehicle speed gain GV is output to the multiplication unit 48.

  As shown in FIG. 7, the vehicle speed gain map is set so that the vehicle speed gain GV is 1.0 in the region where the vehicle speed VC is 0 to VCt. In a region where the vehicle speed VC is equal to or higher than VCth, the vehicle speed gain GV is set to decrease from 1.0 to 0 as the vehicle speed VC increases.

  Subsequently, in the multiplication unit 48, the VGRS addition angle σ acquired by the VGRS addition angle acquisition unit 45, the turning angle gain GA set by the turning angle gain setting unit 46, and the vehicle speed gain setting unit 47 are set. The steering assist variable turning angle is calculated by multiplying the vehicle speed gain GV. The calculated steering assist variable turning angle is output to the variable turning angle calculation / output unit 49.

  Next, in the variable turning angle calculation / output unit 49, the vehicle speed variable turning angle obtained by the vehicle speed variable turning angle calculation unit 42 and the steering assistance variable turning angle obtained by the steering assistance variable turning angle setting unit 44. The target variable turning angle is calculated by adding the steering angle. Then, a control signal corresponding to the calculated target variable turning angle is output to the turning angle varying device 24, whereby the turning angle varying device 24 is driven. As a result, the steering characteristic is changed so that the lower steering shaft 26 is increased or decreased and the travel lane can be traced appropriately.

  According to this embodiment, when the target variable turning angle of the turning angle varying device 24 is calculated based on the steering angle MA and the vehicle speed VC of the steering wheel 14 by the driver, the yaw of the vehicle V with respect to the traveling lane is calculated. The target variable turning angle is corrected based on the angle θ. Therefore, it is possible to set the target variable turning angle so as to obtain a steering characteristic suitable for the traveling lane while being based on the steering based on the driver's intention. As a result, it is possible to appropriately trace the traveling lane without causing the driver to feel uncomfortable.

  At this time, as the yaw angle θ of the vehicle V increases, that is, as the steering wheel 14 is turned too much or the steering wheel 14 is cut less, the VGRS addition angle σ is increased. Since the amount of correction of the target variable turning angle (steering assist variable turning angle) is increased, it is possible to correct the target variable turning angle so as to obtain a steering characteristic suitable for the traveling lane.

  In the present embodiment, the VGRS addition angle map is set so that the rising slope of the VGRS addition angle σ becomes gentler as the steering angular velocity MAdot increases. Therefore, the VGRS addition angle σ increases as the steering angular velocity MAdot increases. Decreases and the correction amount (steering assist variable turning angle) decreases. Thereby, since excessive cutting of the steering wheel 14 is suppressed, an excessive increase in steering response can be suppressed. As a result, the traveling lane can be traced more easily.

  In the present embodiment, the steered angle gain map shows that in the region where the steered angle MA is 0 to MAdz, the steered angle gain GA decreases from 1.0 to 0 (that is, the correction value becomes smaller) as the steered angle MA becomes smaller. Is set to decrease). By providing a dead zone corresponding to the play of the steering wheel 14 in this way, it is possible to suppress hunting of the correction amount with respect to turning on / off of the steering and to reduce the uncomfortable feeling at the time of control intervention. Further, in this case, since the correction amount is set for the main steering by the driver, it is possible to prevent excessive interference in steering assistance.

  In the present embodiment, the vehicle speed gain map is set so that the vehicle speed gain GV decreases from 1.0 to 0 as the vehicle speed VC increases in a region where the vehicle speed VC is equal to or higher than VCth. Although the movement of the vehicle with respect to steering becomes more rapid as the speed increases, according to the present embodiment, the correction value is decreased in a high speed region where the vehicle speed VC is equal to or higher than VCth, so that it is possible to compensate for vehicle characteristics that change with the vehicle speed. It becomes.

  Next, the configuration of the steering assist device 2 according to the second embodiment will be described with reference to FIGS. FIG. 8 is a block diagram for explaining the configuration of the steering assist device 2. FIG. 9 is a diagram showing another example of the VGRS addition angle map.

  The steering assist device 2 according to the present embodiment is replaced with a VGRS ECU 40 in which a steering assist variable turning angle setting unit 44 is constructed as a control device for controlling the turning angle varying device 24, and steering is performed therein. It differs from the steering assistance apparatus 1 which concerns on 1st Embodiment mentioned above by the point which uses VGRS ECU40A with which the assistance variable turning angle setting part 44A was constructed | assembled. Other configurations are the same as or similar to those of the first embodiment, and thus description thereof is omitted here.

  In addition to the configuration of the steering assist variable turning angle setting unit 44 described above, the steering assist variable turning angle setting unit 44A calculates a reference steering angular velocity calculation unit 50 that calculates a reference steering angular velocity MARdot according to the turning radius R of the traveling lane. And a deviation calculator 51 for calculating a deviation Er between the actual steering angular velocity MAdot obtained by differentiating the actual steering angle MA detected by the steering angle sensor 23 and the standard steering angular velocity MARdot. Further, the steering assist variable turning angle setting unit 44A replaces the VGRS addition angle acquisition unit 45 described above with a VGRS addition angle acquisition unit 45A that obtains the VGRS addition angle σ from the yaw angle θ, the steering angular velocity MAdot, and the deviation Er. Have.

  Next, the operation of the steering assist device 2 will be described. However, since the operation of the vehicle speed variable turning angle calculation unit 42 is the same as that of the first embodiment described above, the description thereof is omitted here. Therefore, hereinafter, the operation of the steering assist variable turning angle setting unit 44A different from the first embodiment will be mainly described. In the steering assist variable turning angle setting unit 44A, the steering assistance variable turning angle (correction amount) is set from the yaw angle θ, the turning radius R, the steering angle MA, the steering angular velocity MAdot, and the vehicle speed VC.

First, the reference steering angular velocity calculation unit 50 calculates a reference steering angular velocity MARdot, which is the optimum steering angular velocity in the traveling lane, from the turning radius R of the traveling lane based on the following equation (1). The calculated reference steering angular velocity MARdot is output to the deviation calculator 51.
MARdot = d (((1 + Kh × VC ^ 2) L) / R) / dt (1)
However, Kh is a stability factor. VC is the vehicle speed, L is the wheelbase, and R is the turning radius.

In the deviation calculation unit 51, a deviation Er between the reference steering angular velocity MARdot input from the reference steering angular velocity calculation unit 50 and the actual steering angular velocity MAdot obtained by differentiating the actual steering angle MA detected by the steering angle sensor 23. Is calculated based on the following equation (2). The calculated deviation Er is output to the VGRS addition angle acquisition unit 45A.
Er = MARdot−MAdot (2)

  In the VGRS addition angle acquisition unit 45A, the VGRS addition angle σ is acquired from the yaw angle θ and the deviation Er. The VGRS addition angle acquisition unit 45A is provided with a three-dimensional map (VGRS addition angle map 2) that defines the relationship between the yaw angle θ, the deviation Er, and the VGRS addition angle σ, and includes the yaw angle θ and the deviation Er. The VGRS addition angle map 2 is obtained by searching the VGRS addition angle map 2 on the basis thereof.

  As shown in FIG. 9, the VGRS addition angle map 2 is set so that the VGRS addition angle σ is zero in the region where the yaw angle θ is 0 to θdz. In a region where the yaw angle θ is greater than or equal to θdz, when the deviation Er takes a positive value (that is, when the standard steering angular velocity MARdot is greater than the actual steering angular velocity MAdot), the VGRS addition angle σ increases as the yaw angle θ increases. Is set to On the other hand, when the deviation Er takes a negative value (that is, when the reference steering angular velocity MARdot is smaller than the actual steering angular velocity MAdot), the VGRS addition angle σ is set to decrease as the yaw angle θ increases. That is, the correction amount is changed according to the magnitude relationship between the standard steering angular velocity MARdot and the actual steering angular velocity MAdot.

  Here, as shown in FIG. 9, in the VGRS addition angle map 2, the rising slope of the VGRS addition angle σ when the deviation Er takes a negative value, and the VGRS addition angle when the deviation Er takes a positive value. It is set more gently than the rising slope of σ. This is due to the following reason.

  Taking a so-called out-in-out travel line when turning a curve is preferable in that the amount of steering can be reduced and the turning radius can be increased to stabilize the behavior of the vehicle. Many drivers take such a travel line. When trying to take such an out-in-out driving line, it is necessary to make the steering timing earlier, but here, assuming that the rising slope of the VGRS addition angle σ is the same regardless of whether the deviation Er is positive or negative. The negative VGRS addition angle σ becomes large (that is, the amount of switching back becomes large), which is contrary to the driver's intention to try to go in. On the other hand, it is preferable to increase the VGRS addition angle σ and place it on the in-side for a driver who is late in turning. Therefore, it is preferable that the rising slope of the VGRS addition angle σ has an asymmetric characteristic depending on whether the deviation Er is positive or negative.

  Returning to FIG. 8 and continuing the description, the VGRS addition angle σ acquired by the VGRS addition angle acquisition unit 45 </ b> A is output to the multiplication unit 48. As described above, in the multiplication unit 48, the VGRS addition angle σ acquired by the VGRS addition angle acquisition unit 45A, the turning angle gain GA set by the turning angle gain setting unit 46, and the vehicle speed gain setting unit The steering assist variable turning angle is calculated by multiplying the vehicle speed gain GV set in 47. The calculated steering assist variable turning angle is output to the variable turning angle calculation / output unit 49. The operations of the turning angle gain setting unit 46 and the vehicle speed gain setting unit 47 are the same as in the case of the first embodiment described above, and thus the description thereof is omitted here.

  In the variable turning angle calculation / output unit 49, the vehicle speed variable turning angle obtained by the vehicle speed variable turning angle calculation unit 42, and the steering assistance variable turning angle obtained by the steering assistance variable turning angle setting unit 44A, Is added to calculate the target variable turning angle. Then, a control signal corresponding to the calculated target variable turning angle is output to the turning angle varying device 24, whereby the turning angle varying device 24 is driven. As a result, the steering characteristic is changed so that the lower steering shaft 26 is increased or decreased and the travel lane can be traced appropriately.

  According to this embodiment, when the target variable turning angle of the turning angle varying device 24 is calculated based on the steering angle MA and the vehicle speed VC of the steering wheel 14 by the driver, the yaw of the vehicle V with respect to the traveling lane is calculated. The target variable turning angle is corrected based on the angle θ. Therefore, it is possible to set the target variable turning angle so as to obtain a steering characteristic suitable for the traveling lane while being based on the steering based on the driver's intention. As a result, it is possible to appropriately trace the traveling lane without causing the driver to feel uncomfortable.

  Further, according to the present embodiment, when the actual steering angular velocity MAdot is faster than the standard steering angular velocity MARdot corresponding to the turning radius R of the traveling lane, it is determined that the driver's steering velocity is too high, and the yaw angle θ By changing the VGRS addition angle σ with respect to the minus side, the correction amount is changed so as to switch back the steering wheel 14. As a result, it is possible to perform steering support so as to reduce the meandering traveling.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, the target variable turning angle of the turning angle varying device 24 is corrected based on the yaw angle θ, the steering angle MA, the steering angular velocity MAdot obtained by differentiating the steering angle MA, and the vehicle speed VC. By setting the steering assist variable turning angle (correction amount), the target variable turning angle is corrected so that the steering characteristic suitable for the traveling lane is obtained. Instead, the yaw angle θ, the steering angle MA, The target assist torque of the electric power steering device may be corrected based on the steering angular velocity MAdot, the vehicle speed VC, and the like.

  Further, the mechanism for driving the left and right front wheels 10FL and 10FR to perform auxiliary steering relative to the steering wheel 14 is not limited to the above embodiment. For example, a steering device in which the steering wheel and the rack shaft are mechanically separated and the rack shaft is driven by an electric motor may be used.

  In the above embodiment, the turning radius R of the traveling lane is obtained from the image data acquired by the image processing device 41 with the camera. Instead of or in addition to this, the traveling lane acquired by the car navigation system is used. The turning radius of may be used.

  In the embodiment described above, the VGRS addition angle σ, the turning angle gain GA, and the vehicle speed gain GV are obtained by map search, but may be obtained by an arithmetic expression.

It is a block diagram for demonstrating the structure of the steering assistance apparatus which concerns on 1st Embodiment. It is a figure explaining a road parameter. It is a flowchart which shows the process sequence of steering assistance control. It is a figure which shows an example of a steering gear ratio map. It is a figure which shows an example of a VGRS addition angle map. It is a figure which shows an example of a turning angle gain map. It is a figure which shows an example of a vehicle speed gain map. It is a block diagram for demonstrating the structure of the steering assistance apparatus which concerns on 2nd Embodiment. It is a figure which shows the other example of a VGRS addition angle map.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1, 2 ... Steering assistance apparatus, 10FR, 10FL, 10RR, 10RL ... Wheel, 12FR, 12FL, 12RR, 12RL ... Wheel speed sensor, 14 ... Steering wheel, 16 ... Power steering device, 23 ... Steering angle sensor, 24 ... Roll Steering angle variable device, 25 ... Rotation angle sensor, 40, 40A ... VGRS ECU, 41 ... Image processing device, 42 ... Vehicle speed variable turning angle calculation unit, 44, 44A ... Steering assist variable turning angle setting unit, 45, 45A ... addition angle acquisition unit, 46 ... steering angle gain setting unit, 47 ... vehicle speed gain setting unit, 48 ... multiplication unit, 49 ... variable steering angle calculation / output unit, 50 ... standard steering angular velocity calculation unit, 51 ... deviation calculation V, vehicle.

Claims (7)

Steering state detection means for detecting the steering state of the steering wheel;
Traveling state detecting means for detecting the traveling state of the vehicle;
In a steering support device comprising: control means for calculating a steering support control amount of the steering wheel based on the steering state and the traveling state;
A behavior state detecting means for detecting a behavior state of the vehicle with respect to a traveling lane;
The control means corrects the steering support control amount based on a behavior state of the vehicle when calculating the steering support control amount. The behavior state of the vehicle is a yaw angle of the vehicle,
The steering support device according to claim 1, wherein the control means increases a correction amount for correcting the steering support control amount as the yaw angle increases. A steering speed detecting means for detecting a steering speed of the steering wheel;
The steering assist device according to claim 2, wherein the control unit decreases the correction amount as the steering speed increases. Steering speed detecting means for detecting the steering speed of the steering wheel;
A reference steering speed calculation means for calculating a reference steering speed according to a turning radius of the traveling lane,
The steering assist device according to claim 2, wherein the control unit changes the correction amount according to a magnitude relationship between an actual steering speed detected by the steering speed detection unit and the reference steering speed. .   5. The control unit according to claim 2, wherein the control unit decreases the correction value as the steering angle decreases in a region where the steering angle of the steering wheel is equal to or smaller than a predetermined steering angle. The steering assist device described.   The steering assist according to any one of claims 2 to 5, wherein the control means decreases the correction value as the vehicle speed increases in a region where the vehicle speed of the vehicle is equal to or higher than a predetermined vehicle speed. apparatus.   The steering assist device according to any one of claims 1 to 6, wherein the steering assist control amount is a target variable turning angle of a turning angle variable control that changes a steering gear ratio.

Images