JP6011358B2 - Lane maintenance support device - Google Patents

Description

  The present invention relates to a lane keeping assist device.

  In the case of vehicles, particularly automobiles, steering is performed in a direction opposite to the direction of departure from the lane (that is, the direction toward the center of the lane) in order to support lane maintenance while driving, that is, to prevent lane departure. There is a tendency to increase the number of lane keeping assist torques to be applied. Since the steering force in the direction in which the lane keeping assist torque is applied becomes light, the driver is naturally urged to return to the lane center position. Of course, the magnitude of the assist torque for maintaining the lane is set to a size that can be overcome by the driver so as not to hinder the steering performed when the driver actively changes the lane.

  In general, when a steering wheel is operated, hysteresis is set to reduce the steering torque in the steering angle decreasing direction as compared with the steering torque in the steering angle increasing direction. The hysteresis is set in consideration of the self-aligning torque, the mechanical resistance of the steering system, and the like. This hysteresis setting enhances the steering function and ensures a good steering sensation so that there is no significant difference in steering feeling perceived by the driver between the steering angle increasing direction and the steering angle decreasing direction. Will be obtained.

  Patent Document 1 discloses that the hysteresis width is reduced as the steering angle increases. Patent Document 2 discloses a technique in which the hysteresis width is changed in accordance with the gripping force of the wheel, that is, the lateral G. Patent Document 3 discloses that an actual force, that is, a physical force and a perceptive force perceived by a human differ depending on the magnitude of the force exerted by a human upper limb.

JP 2009-227125 A JP 2011-201388 A JP 2008-125520 A

  By the way, in a vehicle that performs control to apply lane keeping assist torque, it is also important from the viewpoint of reducing driver fatigue. That is, when it is necessary to steer left to maintain the lane, for example, the left lane keeping assist torque is applied to reduce the force exerted by the front part of the right deltoid muscle that is the main driving muscle for left steering. Will be.

  However, it has been found that simply applying a large lane keeping assist torque may cause the driver to get tired. In pursuit of such a cause, for example, during left steering, by applying a large lane keeping assist torque, the muscle strength exerted by the front part of the right deltoid muscle that is the main muscle is greatly reduced, while the left upper arm that is an antagonist muscle It turned out that it was because the muscular strength which a triceps muscle exerted increased. In other words, if the lane keeping assist torque is set to be large so as to significantly reduce the muscle strength exerted by the main muscle, the muscle strength exerted by the antagonist muscles also greatly increases, and therefore the driver's fatigue also increases. It was. In particular, when the steering operation in a predetermined direction to which a large lane keeping assist torque is applied is lightened, the antagonistic muscle is acted greatly to balance the steering wheel operated in the predetermined direction at a certain steering angle. This required increased driver fatigue.

  On the other hand, if the assist torque for maintaining the lane is set small so that the increase in muscle strength exerted by the antagonist muscles is reduced, the muscle strength exerted by the main muscles decreases, but the muscle strength exerted by the antagonist muscles also decreases. Therefore, as a whole, the driver's fatigue is relatively reduced as compared with the case where the lane keeping assist torque is set large.

  However, simply setting the assist torque for maintaining the lane to be small for reducing the driver's fatigue is not preferable for sufficiently exerting the lane maintaining function.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lane keeping assist device capable of preventing or suppressing driver fatigue while enhancing the lane keeping function. is there.

In order to achieve the above object, the following first solution is adopted in the present invention. That is, as described in claim 1,
In the lane keeping assist device in which the assist torque for maintaining the lane in a direction that prevents the own vehicle from deviating from the traveling lane is applied in a size that the driver can overcome,
Basic assist torque determining means for determining basic lane keeping assist torque;
A viscous torque determining means for determining a viscous torque based at least on the steering angular velocity;
Correction means for calculating a final lane keeping assist torque by subtracting the viscous torque determined by the viscous torque determining means from the basic lane keeping assist torque determined by the basic assist torque determining means; ,
A target yaw rate determining means for determining a target yaw rate for maintaining the lane;
An actual yaw rate detection means for detecting the actual yaw rate currently occurring;
Deviation calculating means for calculating a deviation between the target yaw rate determined by the target yaw rate determining means and the actual yaw rate detected by the actual yaw rate detecting means;
With
The viscous torque determining means determines the viscous torque to be larger when the absolute value of the deviation calculated by the deviation calculating means is small even when the steering angular velocity is the same as compared to when it is large.
It is like that.

  According to the above solution, the viscous torque acts as a damper function that increases the stability of the handle, that is, suppresses wobbling of the handle. That is, even if the basic lane keeping assist torque is set large, when the steering wheel stability needs to be increased, the lane keeping assist torque is corrected by the viscous torque so that the muscle strength exerted by the antagonist muscles is corrected. It will be small. As a result, it is possible to prevent or suppress a situation where the driver's fatigue is increased while sufficiently enhancing the lane keeping function.

In addition to the above, the fact that the absolute value of the deviation between the target yaw rate and the actual yaw rate is small can be regarded as being maintained or almost maintained. In this case, the viscous torque is largely determined and the final value is reached. Since the assist torque for maintaining the lane is reduced, the stability of the steering wheel is improved, which is extremely preferable in reducing the driver's fatigue.

A preferred mode based on the first solution is as follows.
The viscous torque determining means determines the viscous torque to decrease as the vehicle speed increases even if the absolute value of the deviation is the same (corresponding to claim 2 ). In this case, the steering wheel operating force changes according to the vehicle speed, but the viscosity torque is set to a more preferable magnitude according to the vehicle speed, which is more preferable for reducing driver fatigue while enhancing the lane keeping function. .

In order to achieve the above object, the following second solution is adopted in the present invention. That is, as described in claim 3,
In the lane keeping assist device in which the assist torque for maintaining the lane in a direction that prevents the own vehicle from deviating from the traveling lane is applied in a size that the driver can overcome,
Basic assist torque determining means for determining basic lane keeping assist torque;
A viscous torque determining means for determining a viscous torque based at least on the steering angular velocity;
Correction means for calculating a final lane keeping assist torque by subtracting the viscous torque determined by the viscous torque determining means from the basic lane keeping assist torque determined by the basic assist torque determining means; ,
A target yaw rate determining means for determining a target yaw rate for maintaining the lane;
An actual yaw rate detection means for detecting the actual yaw rate currently occurring;
Deviation calculating means for calculating a deviation between the target yaw rate determined by the target yaw rate determining means and the actual yaw rate detected by the actual yaw rate detecting means;
Vehicle speed detection means for detecting the vehicle speed;
Steering angular velocity detection means for detecting the steering angular velocity;
With
The viscosity torque determining means is detected by the vehicle speed detecting means so that the viscosity torque increases as the steering angular speed increases, and the absolute value of the deviation detected by the deviation detecting means decreases even at the same steering angular speed. To determine that the viscous torque decreases as the vehicle speed increases.
Ru Citea so. According to the second solving technique, it can be obtained according to claim 1, the effect corresponding to claim 2 together.

  According to the present invention, it is possible to prevent or suppress driver fatigue while sufficiently enhancing the lane keeping function.

The block diagram which shows the example of a control system of the lane maintenance assistance apparatus to which this invention was applied. The characteristic view which shows the example of a change of the width | variety of the hysteresis according to the presence or absence of the assist torque for lane keeping. The figure for demonstrating determination of a target yaw rate. The figure which shows the example of a setting of the front gaze time T in FIG. The characteristic view which shows the example of a setting of the target steering torque which a driver | operator exhibits according to a target yaw rate. The characteristic view which shows the example of a setting of the reference | standard hysteresis width according to steering angular velocity. The figure which shows the example of a setting of a viscous torque. The flowchart which shows the example of control of this invention. Explanatory drawing which shows the main muscle and antagonistic muscle when left-steering. The figure which shows the difference in the muscular strength which the main driving muscle exhibits by presence or absence of this invention control. The figure which shows the difference in the muscular strength which the antagonistic muscle exhibits by the presence or absence of this invention control. The figure which shows another example of a setting of the assist torque for basic lane maintenance. The figure which shows the reference example 1 and shows the difference in the muscular strength which the main driving muscle exhibits when there is no lane keeping control and when lane keeping control is performed without viscous torque. The figure which shows the reference example 1, Comprising: The figure which shows the difference in the muscular strength which the antagonistic muscle exhibits when a lane maintenance control is performed without a lane maintenance control and without a viscous torque. The figure which shows the reference example 2, Comprising: The figure which shows the difference in the muscular strength which the main muscle exerts when there is no lane keeping control and when lane keeping control is performed without viscous torque. The figure which shows the reference example 1, Comprising: The figure which shows the difference in the muscular strength which the antagonistic muscle exhibits when a lane maintenance control is performed without a lane maintenance control and without a viscous torque.

  FIG. 1 is a block diagram showing an example of a control system of the present invention mounted on a vehicle (automobile). In FIG. 1, U is a controller (control unit) configured using a microcomputer. The controller U has a storage means M, and stores various characteristic diagrams and the like used for executing the control described later in addition to the program necessary for the control.

  The controller U receives signals from various sensors and devices S1 to S6. S1 is a steering angle sensor that detects an operation amount of a steering wheel operated by a driver, that is, a steering angle (a steering angle including an operation direction). For example, S2 is a torque sensor that is attached to the steering shaft and detects the steering torque in accordance with the amount of twisting of the steering shaft.

  S3 is a camera that captures the front of the host vehicle, and is used to detect the left and right white line positions that divide the lane in which the host vehicle is traveling and to detect the lateral position of the host vehicle relative to the left and right white line positions. (It also detects the center position of the physical lane). S4 is a vehicle speed sensor that detects the vehicle speed. S5 is a navigation device for detecting the current position of the host vehicle and using the map information to detect the current road condition where the host vehicle is traveling, the road condition ahead, and the like. . S6 is a change-over switch that is manually operated by the driver to select ON (execution) and OFF (execution prohibition) of lane keeping control described later.

  The controller U controls the motor S11 and display means S12 such as a display or a lamp. The motor S11 is incorporated in the steering system and performs power assist. That is, in the embodiment, the power steering mechanism is an electric type in which an assist force is generated by the motor S11. The steering assist force is changed by adjusting (changing) the supply current. The display means S12 is for informing the driver of the ON / OFF state of the changeover switch S6.

  FIG. 2 schematically shows the relationship between the steering angle and the steering torque in accordance with the presence or absence of the lane keeping assist torque. With respect to the steering torque in the direction in which the steering angle increases at the same steering angle, FIG. Thus, the steering torque in the direction in which the steering angle decreases is set to be small, and the difference indicates the hysteresis width. The width of the hysteresis is set large when the lane keeping assist torque indicated by the broken line is not applied, and is set small when the lane keeping assist torque indicated by the solid line is applied. By varying the width of the hysteresis depending on the presence or absence of the lane keeping assist torque, it is possible to make the steering wheel feel almost the same with and without the lane keeping assist torque (physical Even if the amount of change in the steering torque is the same, the amount of change in the perceived steering torque closer to the driver is smaller when the physical steering torque is large than when it is small.

  Next, an example of determining the lane keeping assist torque for lane keeping will be described. First, in the embodiment, as shown in FIG. 3 in which the vehicle is running on the left curve, the target yaw rate calculation required for guiding to the guidance target point α that is the physical lane center position ahead of the host vehicle X is performed. Done. The distance in the forward direction of the host vehicle to the guidance target point α is defined as VT. In this case, V is the vehicle speed and T is the forward gaze time. The forward gaze time is set as a characteristic as shown in FIG. 4, for example, but the point is the target time until the guidance target point α is reached. Basically, the front gaze time T decreases as the vehicle speed increases. (Upper limit value and lower limit value are set).

  The target yaw rate Υtarget required for guiding to the guidance target point α is obtained by the following equation (1) based on the vehicle speed, the lateral position of the host vehicle, the yaw angle, the curvature of the lane, and the clothoid parameter. In equation (1), V is the vehicle speed, T is the forward gaze time, R is the curvature of the lane, Ψ0 is the yaw angle of the host vehicle X, y0 is the lateral position of the host vehicle X, and A is the clothoid parameter. The curvature R and the like can be determined based on the detection result of the camera S3. For example, the curvature R is obtained based on the map information in the navigation device S5 or information from the infrastructure facility set on the roadside. Can be obtained by an appropriate method.

  When the target yaw rate Υtarget is determined, the target yaw rate Υtarget and the vehicle speed are collated with the characteristics shown in FIG. 5, and the target steering torque TDriver to be exhibited by the driver is determined. Next, the steering angular velocity is checked against the characteristic diagram shown in FIG. 6 to determine the hysteresis width. Note that a dead zone is set for the hysteresis width in a region where the steering angular velocity is small (for example, 0.00001 rad / s or less) (steering rattling is prevented). This hysteresis width corresponds to the case where a reference value without the lane keeping assist torque is set. When the lane keeping assist torque is present, the hysteresis width decreases so as to reduce the hysteresis width as described with reference to FIG. It is corrected.

  In order to determine the final output for the power steering apparatus, the following steering torque is determined. First, the steering torque TNormal necessary for the turning described with reference to FIG. 3 is calculated. The standard assist torque corresponding to TDriver is determined as TESP as the steering torque to be exhibited by the driver described above (TESP can also be determined according to the torque detected by torque sensor S2). Then, the basic lane keeping assist torque TBase is calculated based on the following equation (2).

TBase = TNormal-TDriver-TESP (2)
The basic lane keeping assist torque TBase is additionally applied to the case where there is no lane keeping control. When the lane keeping assist torque TBase is applied, the hysteresis width is corrected to be smaller than when the lane keeping assist torque TBase is not applied.

  In addition to the above, the viscous torque TViscosity is determined. This viscous torque TViscosity is calculated by multiplying the steering angular velocity by a gain coefficient C (> 0). The gain count C is determined based on characteristics as shown in FIG. That is, the gain coefficient C is determined to be smaller as the absolute value of the deviation obtained by subtracting the current yaw rate of the host vehicle X from the target yaw rate described in FIG. Further, the gain coefficient C is determined so as to decrease as the vehicle speed increases even if the absolute value of the deviation is the same. Thus, the viscous torque TViscosity is determined so as to increase as the steering angular velocity increases, increase as the deviation (absolute value) decreases, and increase as the vehicle speed decreases.

  The viscous torque TViscosity determined as described above is subtracted from the basic lane keeping assist torque tBase described above to obtain the final lane keeping assist torque TLKA, and this final lane keeping assist torque TLKA. Is output (TLKA output from the motor S11). In particular, when the absolute value of the deviation between the target yaw rate and the actual yaw rate is small, it is at the time of steering or almost at the time of steering. The maintenance assist torque TLKA is reduced and the steering wheel stability is improved (preventing or suppressing the function of the antagonistic muscle).

  FIG. 8 is a flowchart showing a control example for determining (outputting) the above-described final TLKA by the controller U. Hereinafter, this flowchart will be described, but it is assumed that the changeover switch S6 is ON (with lane keeping assist torque control−with viscous torque). In the following description, Q indicates a step. Of course, FIG. 2, FIG. 4, FIG. 6, FIG. 7, Formula (1), Formula (2), etc. are memorize | stored in the memory | storage means M. FIG.

  Based on the above, first, in Q1, signals from various sensors S1 to S6 are read. Next, at Q2, as described in FIG. 3, the target yaw rate Υtaeget is calculated. Thereafter, in Q3, a target steering torque TDriver to be exhibited by the driver is calculated based on FIG. Thereafter, in Q4, a steering torque TNormal necessary for turning for guiding to the guidance target point α in FIG. 3 is calculated.

  After Q4, in Q5, the standard assist torque TESP is calculated based on the target steering torque TDriver calculated in Q3. Thereafter, in Q6, the basic lane keeping assist torque TBase is calculated based on the equation (2). Thereafter, in Q7, the reference hysteresis width is determined based on FIG.

  After Q7, at Q8, the target viscosity torque TViscosity is determined (a gain coefficient C is determined based on FIG. 7, and the gain coefficient C is multiplied by the steering angular velocity). Thereafter, in Q9, the final lane keeping assist torque TLKA is determined by subtracting the viscous torque KTViscosity from the basic lane keeping assist torque TBase determined in Q6. In Q10, a control signal (drive signal) is output to the motor S11 so that the final lane keeping assist torque TLKA is obtained. When the final lane keeping assist torque TLKA is not 0, the reference hysteresis width is corrected to decrease.

  Here, FIG. 9 shows the main muscles and antagonist muscles when the steering wheel is operated to the left. The muscles marked with Δ before the muscle names are antagonist muscles, and the unmarked ones are main muscles. is there. Among these, in particular, the right anterior part of the deltoid muscle acts as a main muscle, and the left triceps acts as an antagonist muscle.

  When the steering wheel is operated to the left, a difference in muscle strength of the main muscle according to the presence or absence of control according to the present invention is shown in FIG. 10, and a difference in muscle strength of the antagonist muscle is shown in FIG. As is apparent from FIG. 10, when the control of the present invention indicated by the solid line is executed, the muscle strength of the main muscle is greatly reduced as compared with the case where the assist torque for maintaining the lane indicated by the broken line is not applied. Is understood. On the other hand, as is clear from FIG. 11, when the control of the present invention indicated by the solid line is executed, the muscle strength of the antagonistic muscle may hardly change compared to the case where the assist torque for maintaining the lane indicated by the broken line is not applied. Understood. That is, it is understood that by performing the control according to the present invention, the driver's fatigue is prevented or suppressed while enhancing the lane keeping function.

  FIGS. 13 and 14 show Reference Example 1, in which the broken line indicates no control of the lane maintaining assist torque, and the solid line indicates that the lane maintaining assist torque is applied (however, no viscous torque is applied). ). As is clear from FIG. 13, the muscle strength exerted by the main muscle is greatly reduced by applying a large assisting torque for maintaining the lane, but the muscle strength exerted by the antagonist muscle is also increased as shown in FIG. 14. This increases the driver's fatigue.

  FIGS. 15 and 16 show Reference Example 2, in which the broken line indicates the case where there is no control of the lane keeping assist torque, and the solid line gives a smaller lane keeping assist torque than in the case of Reference Example 1. The case (however, no viscous torque is applied) is shown. In Reference Example 2, as shown in FIG. 16, the muscle strength exerted by the antagonistic muscle is only slightly increased, which is preferable in reducing the driver's fatigue. On the other hand, as apparent from FIG. The degree of reduction is small.

  FIG. 12 shows a second embodiment of the present invention. In this embodiment, the basic lane keeping assist torque TBase is determined based on the characteristics shown in FIG. In FIG. 12, a dead zone having a predetermined width (for example, 0.4 to 0.5 m) is set in the left-right direction from the physical lane center position, and in this dead zone, lane maintenance assist torque is not applied (prohibited). It is. The lane keeping assist torque is applied only outside the dead zone. In the case of the present embodiment, the hysteresis width is the reference hysteresis width when in the dead band, and is a size obtained by reducing and correcting the reference hysteresis width in the region outside the dead band.

  Although the embodiments have been described above, the present invention is not limited to the embodiments, and appropriate modifications can be made within the scope of the claims. The power assist device is not limited to an electric type but may be a hydraulic type. In addition to using the camera S2, the position of the vehicle in the lateral direction with respect to the lane can be detected by using another sensor such as a radar as an alternative or in cooperation, using a high-precision navigation device, It can be selected as appropriate, for example, by obtaining information from the infrastructure facility from the roadside by communication, or by combining them. As a parameter for determining the viscous torque, it is sufficient that at least the steering angular velocity is included, and there may be a case where the deviation between the target yaw rate and the actual yaw rate and the vehicle speed are not included as parameters. In addition to the steering angular velocity, Either the deviation or the vehicle speed may be added as a parameter. The viscous torque is not limited to the continuously variable type, but may be changed stepwise. The hysteresis width may be always set to the same size. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

  The present invention is suitable as a vehicle lane keeping assist device.

U: Controller (control means)
S1: Rudder angle sensor S2: Torque sensor S3: Camera S4: Vehicle speed sensor S5: Navigation device S6: Changeover switch (for ON / OFF of lane keeping control)
S11: Motor (for power assist)

Claims (3)

In the lane keeping assist device in which the assist torque for maintaining the lane in a direction that prevents the own vehicle from deviating from the traveling lane is applied in a size that the driver can overcome,
Basic assist torque determining means for determining basic lane keeping assist torque;
A viscous torque determining means for determining a viscous torque based at least on the steering angular velocity;
Correction means for calculating a final lane keeping assist torque by subtracting the viscous torque determined by the viscous torque determining means from the basic lane keeping assist torque determined by the basic assist torque determining means; ,
A target yaw rate determining means for determining a target yaw rate for maintaining the lane;
An actual yaw rate detection means for detecting the actual yaw rate currently occurring;
Deviation calculating means for calculating a deviation between the target yaw rate determined by the target yaw rate determining means and the actual yaw rate detected by the actual yaw rate detecting means;
With
The viscous torque determining means determines the viscous torque to be larger when the absolute value of the deviation calculated by the deviation calculating means is small even when the steering angular velocity is the same as compared to when it is large.
A lane keeping assist device characterized by that. In claim 1 ,
The lane keeping assisting device according to claim 1, wherein the viscous torque determining means determines the viscous torque to become smaller as the vehicle speed increases even if the absolute value of the deviation is the same. In the lane keeping assist device in which the assist torque for maintaining the lane in a direction that prevents the own vehicle from deviating from the traveling lane is applied in a size that the driver can overcome,
Basic assist torque determining means for determining basic lane keeping assist torque;
A viscous torque determining means for determining a viscous torque based at least on the steering angular velocity;
Correction means for calculating a final lane keeping assist torque by subtracting the viscous torque determined by the viscous torque determining means from the basic lane keeping assist torque determined by the basic assist torque determining means; ,
A target yaw rate determining means for determining a target yaw rate for maintaining the lane;
An actual yaw rate detection means for detecting the actual yaw rate currently occurring;
Deviation calculating means for calculating a deviation between the target yaw rate determined by the target yaw rate determining means and the actual yaw rate detected by the actual yaw rate detecting means;
Vehicle speed detection means for detecting the vehicle speed;
Steering angular velocity detection means for detecting the steering angular velocity;
With
The viscosity torque determining means is detected by the vehicle speed detecting means so that the viscosity torque increases as the steering angular speed increases, and the absolute value of the deviation detected by the deviation detecting means decreases even at the same steering angular speed. To determine that the viscous torque decreases as the vehicle speed increases.
A lane keeping assist device characterized by that.

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