JP4967484B2 - Lane maintenance support device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lane maintenance assistant device capable of preventing incompatible feeling from being given to a driver by producing suitable assist torque regardless of the steering direction and timing when steering intervention by the driver is performed during control of lane maintenance. <P>SOLUTION: In the lane maintenance assistant device for giving lane maintenance torque Tsup for maintaining the vehicle in the lane based on a position relationship with the lane and the assist torque for assisting steering based on steering torque Tq of the driver to a rack gear for steering a front wheel, an assist torque correction operation part 8c for correcting the assist torque based on a relationship of the direction of the lane maintenance torque Tsup and the direction of the steering torque Tq is provided. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a steering mechanism that steers steered wheels, a lane maintaining torque that maintains the vehicle in the lane based on the positional relationship with the lane, and an assist torque that assists steering based on the steering torque of the driver. Belongs to the technical field of lane keeping support devices.

In the conventional lane keeping assist device, when the driver intervenes during the lane keeping control, in order to give priority to the driver's steering, the output of the lane keeping torque applied to the steering mechanism is suppressed. Yes. (For example, refer to Patent Document 1).
JP 2005-343184 A

  However, the prior art has a problem in that the driver feels uncomfortable because the steering feeling changes depending on the timing and direction of steering intervention by the driver. For example, when the output direction of the lane keeping torque and the direction of the driver's steering torque are the same direction, the steering wheel is light immediately after the start of steering, and the steering wheel becomes heavy after the steering intervention is determined. Conversely, when the output direction of the lane keeping torque and the direction of the steering torque are different, the steering wheel is heavy immediately after the start of steering, and the steering wheel becomes light after the steering intervention is determined.

  The present invention has been made paying attention to the above-mentioned problem, and the object of the present invention is to provide an appropriate assist torque regardless of the steering direction and timing when the driver's steering intervention is made during lane keeping control. An object of the present invention is to provide a lane keeping assist device that can generate and prevent the driver from feeling uncomfortable.

In order to achieve the above object, the present invention provides:
A steering actuator that applies torque to a steering mechanism that steers steering wheels ;
Lane maintaining torque calculating means for calculating a lane maintaining torque for maintaining the vehicle near the center of the lane based on the positional relationship with the lane ;
An assist torque calculating means for calculating an assist torque for assisting steering based on the steering torque of the driver ;
Torque command value calculating means for calculating a torque command value by adding the lane keeping torque and the assist torque;
Actuator control means for driving the steering actuator based on the torque command value;
Torque correction means for correcting the assist torque in a direction to increase when the direction of the lane keeping torque is different from the direction of the steering torque ;
It is provided with.

In lane keeping assist device of the present invention, when the direction of the direction and the steering torque of the vehicle line maintenance torque is different, by performing the correction of increasing the assist torque, which has been conventionally excessive steering reactive with respect to the steering The force can be brought close to an appropriate value. Further, the steering reaction force can be prevented from being lost when the lane keeping torque is restrained by the steering intervention, and the lane keeping control can be smoothly shifted to the assist control.
As a result, when the driver intervenes during the lane keeping control, an appropriate assist torque is generated regardless of the steering direction and timing, and the uncomfortable feeling given to the driver can be prevented.

  Hereinafter, the best mode for carrying out the present invention will be described based on Examples 1 to 5.

First, the configuration will be described.
FIG. 1 is a system configuration diagram illustrating a vehicle steering system to which the lane keeping assist device according to the first embodiment is applied. The lane keeping assist device according to the first embodiment includes a handle 1, a torque sensor 2, an assist motor 3, and the like. The motor position sensor 4, the CCD camera 5, the yaw rate sensor 6, the vehicle speed sensor 7, and the EPS controller 8 are provided.

  The EPS controller 8 calculates an assist torque that reduces the driver's steering burden based on information (steering torque, vehicle speed, steering angle) from the torque sensor 2, the vehicle speed sensor 7, and the motor position sensor 4. Further, road information such as a white line obtained from the CCD camera 5 and a yaw rate that is a rotational speed around the vehicle vertical axis (Z axis) obtained from the yaw rate sensor 6 are acquired, and a lane maintaining torque for maintaining the lane is calculated. .

  In the first embodiment, during the lane keeping control, the sum of the assist torque and the lane keeping torque is used as an assist command value, and this assist command value is input to the assist motor 3. The assist motor 3 drives the assist motor 3 in response to the assist command value, thereby generating a thrust in the rack gear (steering mechanism) 10 via the speed reducer 3a constituted by a worm gear and the steering shaft 9, and the front wheels (Steering wheel) 11 and 11 are steered. Lane maintenance control can be turned ON / OFF by a driver's switch operation.

FIG. 2 is a control block diagram of the EPS controller 8 according to the first embodiment.
The EPS controller 8 reads the signals of the torque sensor 2, the motor position sensor 4, and the vehicle speed sensor 7, and calculates a normal basic assist torque Ta at the basic assist command value calculation unit 8a. As a setting method of the basic assist torque Ta, for example, the basic assist torque Ta is increased as the steering torque is increased, and is decreased as the vehicle speed is decreased.

  The lane keeping torque calculation unit 8b acquires an image ahead of the vehicle from the camera image during lane keeping control, and based on signals such as a vehicle speed signal, a yaw rate, a steering torque, and a steering angle, ) Is calculated, the lane keeping torque Tsup of the assist motor 3 for obtaining the target yaw rate is calculated, and the lane keeping control execution flag Fsup is output.

  The assist torque correction calculation unit (torque correction means) 8c is roughly divided into two. One is a reverse assist torque calculator 8d that calculates the reverse assist torque Tra, and the other is a torque correction gain calculator 8e that calculates a torque correction gain Gt.

The reverse assist torque calculator 8d calculates a reverse assist torque Tra that is proportional to the differential value of the steering torque Tq from the steering torque Tq, the vehicle speed V, and the steering speed ω. The reverse assist torque Tra is intended to improve steering stability by reducing the assist torque against a transient torque change.
The torque correction gain calculator 8e calculates and outputs a torque correction gain Gt according to the steering torque direction d.

The assist correction torque Trev, which is an output of the assist torque correction calculation unit 8c, is calculated by adding the correction gain Gt to the reverse assist torque Tra.
Finally, the basic assist torque Ta and the lane keeping torque Tsup are added, and the assist correction torque Trev is subtracted from the sum to calculate the motor torque command value Ta ′, and the assist motor 3 is driven by the motor control unit 8f.

[Torque correction gain calculation control processing]
FIG. 3 is a flowchart showing a flow of torque correction gain calculation control processing executed by the torque correction gain calculation unit 8e of the first embodiment. Each step will be described below. This control process is repeatedly executed every predetermined calculation cycle.

  In step S1, the steering torque direction d, the lane keeping control execution flag Fsup, and the lane keeping torque Tsup are read, and the process proceeds to step S2.

  In step S2, it is determined whether the lane keeping control execution flag Fsup is ON. If it is ON, the process proceeds to step S3. If it is OFF, the process proceeds to step S8.

  In step S3, it is determined whether the direction of the lane keeping torque Tsup is right (Tsup> 0). If YES, the process proceeds to step S4. If NO, the process proceeds to step S5.

  In step S4, it is determined whether or not the steering torque direction d is right (d> 0). In the case of the right, the process proceeds to step S6, and in the case of NO, the process proceeds to step S7.

  In step S5, it is determined whether or not the steering torque direction d is left (d <0). If YES, the process proceeds to step S6, and if NO, the process proceeds to step S7.

  In step S6, the torque correction gain Gt is set to 1.2, and the process proceeds to step S9.

  In step S7, the torque correction gain Gt is set to -0.2, and the process proceeds to step S9.

  In step S8, the torque correction gain Gt is set to 1.0, and the process proceeds to step S9.

  In step S9, the torque correction gain Gt is output, and the process proceeds to return.

  In the flowchart of FIG. 3, when the driver performs steering intervention during the lane keeping control, if the lane keeping torque and the steering torque are in the same direction, the direction in which the assist torque is reduced is corrected. That is, the flow proceeds from step S1 → step S2 → step S3 → step S4 → step S6 or step S1 → step S2 → step S3 → step S5 → step S6. In step S6, the torque correction gain Gt is set to 1.2. .

  On the other hand, when the direction of the lane keeping torque and the driver's steering torque are different, the direction is corrected so as to increase the assist torque. That is, the process proceeds from step S1, step S2, step S3, step S4, step S7, or step S1, step S2, step S3, step S5, and step S7. In step S7, the torque correction gain Gt is set to -0.2.

  When the lane keeping control is not performed, the assist torque is not corrected. That is, the process proceeds from step S1 to step S2 to step S8, and the torque correction gain Gt is set to 1.0.

Next, the operation will be described.
[Deterioration of steering feeling due to interference between assist torque and lane keeping torque]
In the conventional lane keeping assist device, the front of the vehicle is imaged with a camera or the like, the own lane is detected based on the captured image or video, and the lane keeping torque is applied to the steering mechanism so as to avoid deviation from the own lane. And the front wheels are steered. When the steering torque during the lane keeping control becomes equal to or greater than the threshold value, it is determined that the driver has intervened in steering, and the driver's steering is prioritized by suppressing the lane keeping torque.

  Here, since the driver's steering intervention is determined based on the detected value of the steering torque sensor, in the driving support device described in Japanese Patent Laid-Open No. 2005-343184, the output direction of the lane keeping torque and the steering torque When the directions match, the threshold value for determining the steering intervention is increased. On the other hand, when the output direction of the lane keeping torque and the direction of the steering torque are different, the threshold value for determining the steering intervention is decreased.

  That is, when the directions of the lane keeping torque and the steering torque are different, it can be detected relatively clearly that the driver wants the control opposite to the lane keeping control. On the other hand, if the directions of the lane keeping torque and the steering torque coincide with each other, it means that the driver wants to steer more than the lane keeping control steers. It is difficult to detect because the direction is the same.

  Therefore, in the above prior art, in the case of the former, which is relatively easy to detect, the threshold for determination is made small, in other words, by setting the threshold in the latter case large, both can be detected. It is possible to do it reliably. In this way, the driver's intention can be accurately grasped, and when the steering by the driver should be prioritized over the lane keeping control, the steering by the driver can be more surely prioritized.

  However, as shown in FIG. 4 (a), the steering torque and lane keeping torque directions (i) do not coincide with each other depending on the timing of steering by the driver (FIG. 4 (b)) and (ii) coincide with each other ( 4 (c)), when a steering intervention is made, the steering feeling changes depending on the timing and direction of steering, giving the driver an uncomfortable feeling.

  As shown in FIG. 5, when the steering torque and the lane keeping torque are in the same direction, the lane keeping torque is output in the same direction as the steering torque. The rise of the steering torque detected by the sensor becomes small. When the steering torque exceeds the threshold value, the steering intervention determination is made and the output of the lane keeping torque is stopped. That is, when the directions of the steering torque and the lane keeping torque match, the steering wheel feels that the steering wheel is light immediately after the start of steering and the steering wheel becomes heavy after the steering intervention is judged.

  As shown in FIG. 6, when the directions of the steering torque and the lane keeping torque do not match, the lane keeping torque is outputted in the opposite direction to the steering torque, so the motor output is lower than the case without the lane keeping torque, Steering reaction force rises early. Therefore, the output of the lane keeping torque is stopped by making an early steering intervention determination. That is, if the directions of the steering torque and the lane keeping torque do not match, the steering wheel feels heavy immediately after the start of steering, and the steering wheel becomes light after the steering intervention is judged.

[Assist torque correction logic]
On the other hand, in the lane keeping assist device of the present invention, the assist torque is corrected based on the relationship between the direction of the lane keeping torque and the direction of the steering torque.

  FIG. 7 is a time chart showing the assist torque correction logic when the lane keeping torque and the steering torque are in the same direction. At time t1, the driver starts steering input in the same direction as the lane keeping torque. Is corrected in the decreasing direction. At this time, since the lane keeping torque is in the same direction as the steering torque input, the motor output is increased and the steering torque input is smaller than that without the lane keeping torque. The actual driver steering torque (= steering reaction force) has a sufficient reaction force due to the correction of the assist torque as compared to the case without correction.

  At time t2, the steering torque has exceeded the threshold value, so the lane keeping control is terminated by the steering intervention determination. At time t3, the lane keeping torque becomes zero, but the steering torque is not corrected by correcting the assist torque. Therefore, the fluctuation of the steering torque accompanying the end of the lane keeping control is suppressed.

  FIG. 8 is a time chart showing the assist torque correction logic when the direction of the lane keeping torque and the steering torque do not match. At time t1, the driver starts the steering input in a direction different from the lane keeping torque. Correction to increase the value is performed. At this time, since the lane keeping torque is in the opposite direction to the steering torque input, the motor output decreases and the steering torque input becomes larger than in the case without the lane keeping torque. Then, the actual driver steering torque is reduced by the correction of the assist torque as compared with the case without the correction, and an appropriate steering reaction force can be obtained.

  At time t2, the steering torque has exceeded the threshold value, so the lane keeping control is terminated by the steering intervention determination. At time t3, the lane keeping torque becomes zero, but the steering torque is not corrected by correcting the assist torque. As compared with, steering torque loss due to the end of the lane keeping control is suppressed.

[Assist torque correction]
FIG. 9 is a time chart showing the assist torque correction operation of the first embodiment. At time t1, the driver starts steering input in the same direction as the lane keeping torque, but the assist torque is expressed as a differential value of the steering torque. Due to the action of the corresponding reverse assist torque, the steering wheel 1 is output in the direction of increasing its weight. At this time, since the lane keeping torque is in the same direction as the steering torque input, the motor output rises and the steering torque input becomes smaller than when there is no lane keeping torque. The actual driver steering torque has a sufficient reaction force due to the correction of the assist torque as compared with the case without the correction.

  At time t2, the steering torque has exceeded the threshold value, so the lane keeping control is terminated by the steering intervention determination. At time t3, the lane keeping torque becomes zero, but the steering torque is not corrected by correcting the assist torque. Therefore, the fluctuation of the steering torque accompanying the end of the lane keeping control can be suppressed. Further, an appropriate steering reaction force can be given to the driver without degrading the performance of the lane keeping control before the steering intervention.

[Modification of Example 1]
In the first embodiment, the reverse assist torque calculation unit 8d calculates the reverse assist torque Tra that is proportional to the differential value of the steering torque Tq. However, the steering torque Tq is equal to or higher than the torque dead zone that does not output the assist torque near the neutral position, and When the torque is equal to or less than the first set torque near zero, a configuration may be adopted in which a reverse assist torque corresponding to the steering torque is applied.

  That is, in this modification, when the steering torque Tq is equal to or greater than the torque dead zone and equal to or less than the first set torque, the steering reaction force is generated according to the steering torque. Therefore, the direction of the steering reaction force until the steering torque becomes zero. Does not change. Therefore, it is possible to prevent a change in the steering reaction force direction at the neutral position that gives the driver a sense of incongruity.

  FIG. 10 is a time chart showing an assist torque correction action when the directions of the lane keeping torque and the steering torque do not coincide with each other in the lane keeping assist device to which this modification is applied. At time t1, the direction is different from the lane keeping torque. Since the driver has started steering input, correction for increasing the assist torque is performed. At this time, since the lane maintaining torque is in the opposite direction to the steering torque input, the motor output decreases and the steering torque input increases compared to the case without the lane maintaining torque. Then, the actual driver steering torque is reduced by the correction of the assist torque as compared with the case without the correction, and an appropriate steering reaction force can be obtained.

  At time t2, the steering torque has exceeded the threshold value, so the lane keeping control is terminated by the steering intervention judgment, and at time t3, the lane keeping torque becomes zero, but the lane keeping torque is corrected by the assist torque correction, compared with the case where there is no correction. The sudden decrease of the steering torque accompanying the end of the maintenance control, that is, the steering torque loss is suppressed. Further, an appropriate steering reaction force can be given to the driver without degrading the performance of the lane keeping control before the steering intervention.

Next, the effect will be described.
The lane keeping assist device according to the first embodiment has the following effects.

  (1) Assist for assisting steering with respect to the rack gear 10 that steers the front wheels 11 and 11 based on the lane maintaining torque Tsup that maintains the vehicle in the lane based on the positional relationship with the lane and the driver's steering torque Tq In the lane keeping assist device that applies torque, an assist torque correction calculation unit 8c that corrects the assist torque is provided based on the relationship between the direction of the lane keeping torque Tsup and the direction of the steering torque Tq. Thereby, when the driver's steering intervention is performed during the lane keeping control, an appropriate assist torque is generated regardless of the steering direction and timing, and the uncomfortable feeling given to the driver can be prevented.

  (2) When the direction of the lane keeping torque Tsup and the direction of the steering torque Tq are the same, the assist torque correction calculation unit 8c corrects the assist torque in a direction to decrease, so that steering at the time of steering, which has been insufficient in the past, is performed. The reaction force can be brought close to an appropriate value. Further, it is possible to suppress the fluctuation of the steering reaction force when the lane keeping torque Tsup is suppressed by the steering intervention determination, and to smoothly shift from the lane keeping control to the assist control.

  (3) When the direction of the lane keeping torque Tsup is different from the direction of the steering torque Tq, the assist torque correction calculation unit 8c corrects the assist torque in the direction of increasing the steering torque. The reaction force can be brought close to an appropriate value. Further, the steering reaction force can be prevented from being lost when the lane keeping torque Tsup is restrained by the steering intervention, and the lane keeping control can be smoothly shifted to the assist control.

  (4) A reverse assist torque calculation unit 8d for applying the reverse assist torque Tra in the direction of increasing the steering torque is provided, and the assist torque correction calculation unit 8c corrects the reverse assist torque Tra so that the lane keeping control before the steering intervention is performed. An appropriate steering reaction force can be applied to the driver without degrading the performance of the vehicle.

  The second embodiment is an example in which the reverse assist torque calculation of the first embodiment is calculated with a value proportional to the torque value, and the steering speed ω is added to the input of the torque correction gain calculation unit.

First, the configuration will be described.
FIG. 11 is a control block diagram of the EPS controller 8 according to the second embodiment. The assist torque correction calculation unit 8c passes the steering torque Tq through a primary low-pass filter and multiplies a gain according to the vehicle speed V. Then, the reverse assist torque value Tra is calculated. On the other hand, in the torque correction gain calculation unit 8e, in addition to the torque direction d, the lane keeping torque Tsup, and the lane keeping control execution flag Fsup, the steering speed ω is also input, and the combination of the steering torque direction and the lane keeping torque direction and the steering speed ω The torque correction gain Gt is calculated based on the value of.

[Torque correction gain calculation control processing]
FIG. 12 is a flowchart showing a flow of torque correction gain calculation control processing executed by the torque correction gain calculation unit 8e of the second embodiment. Each step will be described below. In addition, the same step number is attached | subjected to the step which performs the process same as Example 1 shown in FIG. 3, and description is abbreviate | omitted.

  In step S11, the steering torque direction d, the lane keeping control execution flag Fsup, the lane keeping torque Tsup, and the steering speed ω are read, and the process proceeds to step S2.

  In step S12, it is determined whether or not the direction of the steering speed ω is the same as the direction of the steering torque direction d. If YES, the process proceeds to step S13. If NO, the process proceeds to step S8.

  In step S13, it is determined whether or not the direction of the steering speed ω is equal to or greater than a predetermined value. If YES, the process proceeds to step S7, and if NO, the process proceeds to step S8. Here, the predetermined value is a value indicating the turning speed at the time of steering and at the time of minute steering, for example, 5 deg / s.

Next, the operation will be described.
[Assist torque correction]
In the second embodiment, when the direction of the lane keeping torque Tsup is different from the direction of the steering torque Tq, the reverse assist torque Tra is corrected only when the steering speed ω is equal to or higher than a predetermined value (5 deg / s). That is, in the flowchart of FIG. 12, the process proceeds from step S11 → step S2 → step S3 → step S5 → step S12 or step S11 → step S2 → step S3 → step S4 → step S12. Subsequently, in step S12, if the direction of the steering speed ω is the same direction as the steering torque direction d, the process proceeds to step S13, and if the absolute value of ω is equal to or greater than a predetermined value (5 deg / s), the process proceeds to step S7. The torque correction gain Gt is set to -0.2.

  FIG. 13 is a time chart showing the assist torque correction action when the driver is willing to change lanes. When the driver intends to change lanes, it is desirable to suppress torque fluctuation during steering, for example, when the steering wheel is cut. In the second embodiment, it is determined that there is an intention to change the lane based on the inclination of the steering torque → high, the steering speed ω ≧ predetermined value (5 deg / s), the steering torque → high, and the driver's steering at time t1 If the steering speed ω becomes equal to or greater than the predetermined value at time t2 during steering intervention determination after starting, the lane keeping control at time t3 is increased by increasing the assist torque correction amount relative to the steering torque change amount. Steering force fluctuation before and after ending can be suppressed.

  FIG. 14 is a time chart showing the assist torque correction action during steering. It is desirable to maintain the lane keeping ability as much as possible at the time of steering while the driver does not intend to change lanes. In the second embodiment, it is determined that there is no intention to change the lane based on the inclination of the steering torque → small, the steering speed ω <predetermined value (5 deg / s), and the steering torque → small, and the steering from time t1 to time t2 is determined. When the steering torque fluctuates during intervention judgment, if the steering speed ω does not exceed the predetermined value, the assist torque is not corrected, so the lane keeping torque is maintained and the lane keeping ability is maintained by the lane keeping control. can do.

Next, the effect will be described.
The lane keeping assist device of the second embodiment has the following effects.

  (5) When the direction of the lane keeping torque Tsup is different from the direction d of the steering torque Tq, the assist torque correction calculation unit 8c calculates the assist torque only when the steering wheel steering speed ω is equal to or greater than a predetermined value (5 deg / s). Since the correction is performed, it is possible to prevent a decrease in the ability of the lane keeping control when a minute torque is applied, such as during steering.

  The third embodiment is an example in which the torque correction gain calculation of the first embodiment is changed according to the lane keeping torque Tsup.

First, the configuration will be described.
FIG. 15 is a control block diagram of the EPS controller 8 according to the third embodiment. In the assist torque correction calculation unit 8c, the reverse assist torque Tra is multiplied by the torque correction gain Gt calculated by the torque correction gain calculation unit 8e. Thus, the assist correction torque Trev is calculated.

  The torque correction gain calculation unit 8e calculates the torque correction gain Gt according to the gain map as shown in FIG. 16 according to the torque direction d and the direction and magnitude of the lane keeping torque Tsup.

  FIG. 16 (a) is a torque correction gain map according to the lane keeping torque when the lane keeping torque and the direction of the steering torque by the driver coincide with each other. If they coincide, it is necessary to increase the steering reaction force. Therefore, within the range of 1.0 to 2.0, the torque correction gain is increased as the lane keeping torque is increased.

  FIG. 16B is a torque correction gain map according to the lane keeping torque when the lane keeping torque and the direction of the steering torque by the driver do not coincide. If they do not coincide, it is necessary to reduce the steering reaction force. In the range of -1.0 to 1.0, the torque correction gain is decreased as the lane keeping torque increases.

[Torque correction gain calculation control processing]
FIG. 17 is a flowchart showing the flow of torque correction gain calculation control processing executed by the torque correction gain calculation unit 8e of the third embodiment. Each step will be described below. In addition, the same step number is attached | subjected to the step which performs the process same as Example 1 shown in FIG. 3, and description is abbreviate | omitted.

  In step S21, the torque correction gain Gt is calculated from the lane keeping torque Tsup read in step S1 with reference to the torque correction gain map of FIG. 16A, and the process proceeds to step S9.

  In step S22, the torque correction gain Gt is calculated from the lane maintaining torque Tsup read in step S1 with reference to the torque correction gain map of FIG. 16B, and the process proceeds to step S9.

Next, the operation will be described.
[Assist torque correction]
In the third embodiment, the magnitude of the torque correction gain Gt is changed according to the magnitude of the lane keeping torque Tsup.

  If the lane keeping torque and the direction of the steering torque by the driver coincide with each other, in the flowchart of FIG. 17, in step S1, step S2, step S3, step S4, step S21, or step S1, step S2, step S3, The process proceeds from step S5 to step S21. In step S21, the torque correction gain Gt is increased as the lane keeping torque Tsup increases.

  If the direction of the lane keeping torque and the steering torque by the driver do not match, go to Step S1, Step S2, Step S3, Step S5, Step S22, or Step S1, Step S2, Step S3, Step S4, Step S22 In step S22, the torque correction gain Gt is lowered as the lane keeping torque Tsup increases.

  FIG. 18 is a time chart showing the assist torque correction action when the lane keeping torque and the steering torque are in the same direction. At time t1, the driver starts steering input in the same direction as the lane keeping torque. The assist torque is corrected in the direction in which the steering wheel 1 is made heavier by the action of the assist torque, and a sufficient reaction force rise can be obtained compared to the case without the correction, and the lane maintaining torque before and after the end of the lane maintaining control (time point t2). Steering force fluctuation at the time of setting to zero is suppressed. In the second embodiment, the assist torque is corrected so that the steering wheel 1 becomes heavier as the lane keeping torque increases from the time t1 to the time t2. Therefore, the road surface reaction force that changes depending on the magnitude of the lane keeping torque is reduced. It can be appropriately reflected in the force, and a more natural steering feeling can be obtained.

Next, the effect will be described.
The lane keeping assist device of Embodiment 3 has the following effects.

  (6) Since the assist torque correction calculation unit 8c changes the amount of assist torque correction according to the magnitude of the lane keeping torque Tsup, the road surface reaction force that changes depending on the magnitude of the lane keeping torque Tsup is appropriately changed to the steering reaction force. Can be reflected, and a more natural steering feeling can be obtained.

  In the fourth embodiment, the torque correction gain calculation unit 8e of the second embodiment is changed according to the steering torque Tq, the lane keeping control execution flag Fsup, the lane keeping torque Tsup, the reverse assist torque Tra, and the basic assist torque Ta. It is.

First, the configuration will be described.
FIG. 19 is a control block diagram of the EPS controller 8 according to the fourth embodiment. In the fourth embodiment, when the steering torque direction and the lane keeping torque direction coincide with each other, the motor torque command value Ta ′ becomes the lane keeping torque Tsup. The assist correction torque Trev is calculated so as to be equal.

That is,
(Steering torque + Basic assist torque) + Lane maintenance torque-Correction torque = Lane maintenance torque
Ta '= (Ta + Tq) + Tsup-Trev = Tsup, Trev = Ta + Tq
From Trev = Tra (reverse assist torque) x Gt (torque correction gain)
Gt = (Tq + Ta) / Tra
The operation is performed so that

[Torque correction gain calculation control processing]
FIG. 20 is a flowchart showing the flow of torque correction gain calculation control processing executed by the torque correction gain calculation unit 8e of the fourth embodiment. Each step will be described below. In addition, the same step number is attached | subjected to the step which performs the process same as Example 1 shown in FIG. 3, and description is abbreviate | omitted.

  In step S31, the steering torque direction d, the steering torque Tq, the basic assist torque Ta, the lane keeping torque Tsup, the reverse assist torque Tra, and the lane keeping control execution flag Fsup are read, and the process proceeds to step S2.

  In step S32, a torque correction gain Gt is calculated from the steering torque Tq, basic assist torque Ta, and reverse assist torque Tra read in step S31 using the equation Gt = (Tq + Ta) / Tra, and the process proceeds to step S9.

Next, the operation will be described.
[Assist torque correction]
In the fourth embodiment, when the lane keeping torque Tsup and the torque direction d are the same direction, the reverse assist torque Tra is corrected so that the lane keeping torque Tsup does not change. That is, in the flowchart of FIG. 20, the process proceeds from step S31 → step S2 → step S3 → step S4 → step S32 or step S31 → step S2 → step S3 → step S5 → step S32. The torque correction gain Gt is set so that Tsup remains unchanged.

  FIG. 21 is a time chart showing the assist torque correction action when the lane keeping torque and the steering torque are in the same direction. At time t1, the driver starts steering input in the same direction as the lane keeping torque. The assist torque is corrected in the direction of increasing 1. At this time, in the third embodiment, the assist torque is reduced by an amount corresponding to the increase of the steering torque so that the lane keeping torque of the entire system does not change, that is, the steering torque + the assist amount + the assist torque correction amount = 0. The assist torque is corrected. Therefore, at the time of steering intervention determination at time points t1 to t2, it is possible to smoothly shift from the lane keeping control to the assist control while maintaining the lane keeping ability by the lane keeping control.

Next, the effect will be described.
The lane keeping assist device according to the fourth embodiment has the following effects.

  (7) When the direction of the lane keeping torque Tsup is the same as the direction of the steering torque Tq, the assist torque correction calculating unit 8c corrects the assist torque so that the lane keeping torque Tsup does not change. An appropriate steering reaction force can be obtained while maintaining.

  The fifth embodiment is an example in which the assist torque correction calculation unit 8c of the first embodiment is provided with a torque correction execution determination unit 8g that receives the steering torque differential value Tq ′ and the lane keeping control execution flag Fsup as inputs.

First, the configuration will be described.
FIG. 22 is a control block diagram of the EPS controller 8 according to the fifth embodiment. The torque correction execution determination unit 8g starts correction (ON) at the moment when the lane maintenance control execution flag Fsup is turned ON, and performs lane maintenance control. A torque correction execution flag Fjudg is output so that the correction is completed (OFF) when the flag Fsup is OFF and the direction of the steering torque change is changed.

  According to the torque correction execution flag Fjudg, the torque correction gain calculation unit 8e does not perform correction when the torque correction execution flag Fjudg is OFF, and uses the torque correction gain Gt as the reverse assist torque when the torque correction execution flag Fjudg is ON. The assist torque is corrected by adding to Tra.

[Torque correction execution flag output control processing]
FIG. 23 is a flowchart illustrating the flow of torque correction execution flag output control processing executed by the torque correction execution determination unit 8g according to the fifth embodiment. Each step will be described below. This control process is repeatedly executed every predetermined calculation cycle.

  In step S51, a torque correction execution flag Fjudg, a torque differential direction inversion flag Frev, an old torque differential direction inversion flag Frev_pre, and an old steering torque differential value Tq′pre are initialized, and the process proceeds to step S52.

  In step S52, the steering torque differential value Tq ′ and the lane keeping control execution flag Fsup are read, and the process proceeds to step S53.

  In step S53, the steering torque differential value Tq ′ read in step S52 is compared with the old steering torque differential value Tq′pre, and the steering direction changes based on whether Tq ′ × Tq′pre <0. It is determined whether or not. If YES, the process moves to step S54, and if NO, the process moves to step S56.

  In step S54, the old torque differential direction inversion flag is updated with Frev_pre = Frev, and the process proceeds to step S55.

  In step S55, the torque differential direction inversion flag Frev is inverted, and the process proceeds to step S57.

  In step S56, the previous value of the torque differential direction inversion flag Frev is kept, and the process proceeds to step S57.

  In step S57, it is determined whether the lane keeping control execution flag Fsup read in step S52 is ON. If it is ON, the process proceeds to step S60. If NO, the process proceeds to step S58.

  In step S58, it is determined whether or not the torque correction execution flag Fjudg remains ON. If it is ON, the process proceeds to S59, and if it is NO, the process proceeds to Step S61.

  In step S59, it is determined whether or not the torque differential direction reversal flag Frev has changed from the previous value. If YES, the process proceeds to step S61, and if NO, the process proceeds to step S60.

  In step S60, the torque correction execution flag Fjudg = ON is set, and the process proceeds to step S62.

  In step S61, the torque correction execution flag Fjudg = OFF is set, and the process proceeds to step S62.

  In step S62, the torque correction execution flag Fjudg set in step S60 or step S61 is output, and the process proceeds to step S52.

[Torque correction gain calculation control processing]
FIG. 24 is a flowchart showing the flow of torque correction gain calculation control processing executed by the torque correction gain calculation unit 8e of the fifth embodiment. Each step will be described below. This flowchart is repeatedly executed at a predetermined calculation cycle while the torque correction execution flag Fjudg is ON. In addition, the same step number is attached | subjected to the step which performs the same process as Example 1 shown in FIG. 3, and description is abbreviate | omitted.

  In step S41, the steering torque direction d and the lane keeping torque Tsup are read, and the process proceeds to step S3.

Next, the operation will be described.
[Assist torque correction after lane keeping control]
In the fifth embodiment, when the driver's steering intervention is performed during the lane keeping control, even if the steering torque becomes equal to or greater than the threshold value and the lane keeping control is terminated, the direction of the steering torque change is changed. During this period, the assist torque correction is continued.

  That is, in the flowchart of FIG. 23, when the driver starts steering, the process proceeds from step S51 → step S52 → step S53 → step S56 → step S57 → step S60, and in step S60, the torque correction execution flag Fjudg is turned on. Therefore, until the lane keeping control is finished, the flow of steps S52 → step S53 → step S56 → step S57 → step S60 → step S62 is repeated, and the correction of the assist torque is started.

  When the lane keeping control is terminated by the steering intervention determination, the step S52 → the step S53 → the step S56 → the step S57 → the step S58 → the step S59 → the step S60 until the torque differential direction reversal flag Frev is reversed in the step S59. → Since the process of proceeding to step S62 is repeated, the assist torque is continuously corrected.

  If the direction of change in steering torque has changed, the process proceeds from step S52 → step S53 → step S54 → step S55 → step S57 → step S58 → step S59 → step S61. In step S61, the torque correction execution flag Fjudg is turned off. Therefore, the correction of the assist torque is finished.

  FIG. 25 is a time chart showing the steering force fluctuation when the assist torque correction is completed simultaneously with the end of the lane keeping control as a comparative example of the fifth embodiment. After starting assist torque correction by steering intervention at time t1, if assist torque correction is completed at the same time as lane maintenance control at time t2, the assist correction amount is around before time t3 when the assist torque correction amount becomes zero. Because of sudden change, steering reaction force fluctuation occurs.

  On the other hand, in the fifth embodiment, as shown in FIG. 26, the steering intervention determination is made at time t2, and the torque differentiation direction is reversed at time t4 even after the lane keeping torque becomes zero at time t3. In the meantime, the assist torque is corrected in the direction in which the handle 1 is made heavier. Thereby, torque fluctuations before and after the end of assist torque correction can be suppressed.

Next, the effect will be described.
The lane keeping assist device according to the fifth embodiment has the following effects.

  (8) Since the assist torque correction calculation unit 8c continues the correction of the assist torque until the direction of the change of the steering torque of the driver is reversed after the end of the lane keeping control, the steering before and after the end of the correction of the assist torque is performed. Variations in the reaction force can be suppressed.

(Other examples)
As mentioned above, although the best form for implementing this invention was demonstrated based on Examples 1-5, the specific structure of this invention is not limited to Examples 1-5, The invention of Design changes and the like within a range that does not depart from the gist are also included in the present invention.

  For example, in the first to fifth embodiments, the actuator that generates the lane keeping torque and the actuator that generates the assist torque are the same motor 3, but different actuators may be used.

  In the first embodiment, the torque correction gain Gt is multiplied by the reverse assist torque Tra. However, the same effect can be obtained by changing the vehicle speed gain and the angular speed gain of the reverse assist torque calculator 8d according to the torque direction.

1 is a system configuration diagram illustrating a vehicle steering system to which a lane keeping assist device of Example 1 is applied. FIG. FIG. 3 is a control block diagram of the EPS controller 8 according to the first embodiment. It is a flowchart which shows the flow of the torque correction gain calculation control processing performed in the torque correction gain calculation part 8e of Example 1. FIG. It is a figure which shows deterioration of the steering feeling by interference of assist torque and lane keeping torque. It is a figure which shows the omission of steering force in case the direction of steering torque and lane keeping torque corresponds. It is a figure which shows the rapid increase of a steering force when the direction of a steering torque and a lane keeping torque does not correspond. It is a time chart which shows the assist torque correction logic in case the direction of the lane maintenance torque of this invention, and a steering torque correspond. It is a time chart which shows the assist torque correction logic when the directions of the lane keeping torque and the steering torque of the present invention do not match. 3 is a time chart illustrating an assist torque correcting operation of the first embodiment. 6 is a time chart showing an assist torque correction action when the directions of the lane keeping torque and the steering torque do not match in the modification of the first embodiment. FIG. 10 is a control block diagram of the EPS controller 8 according to the second embodiment. It is a flowchart which shows the flow of the torque correction gain calculation control processing performed in the torque correction gain calculation part 8e of Example 2. FIG. In Example 2, it is a time chart which shows the assist torque correction effect | action when a driver | operator has a lane change intention. In Example 2, it is a time chart which shows the assist torque correction effect | action at the time of steering. FIG. 10 is a control block diagram of an EPS controller 8 according to a third embodiment. 10 is a torque correction gain map of Example 3. It is a flowchart which shows the flow of the torque correction gain calculation control processing performed by the torque correction gain calculation part 8e of Example 3. 12 is a time chart showing an assist torque correction operation when the lane keeping torque and the direction of the steering torque coincide with each other in the third embodiment. FIG. 10 is a control block diagram of an EPS controller 8 according to a fourth embodiment. It is a flowchart which shows the flow of the torque correction gain calculation control processing performed by the torque correction gain calculation part 8e of Example 4. It is a time chart which shows the assist torque correction effect | action when the direction of the lane maintenance torque of Example 4 and the direction of steering torque correspond. FIG. 10 is a control block diagram of an EPS controller 8 according to a fifth embodiment. It is a flowchart which shows the flow of the torque correction execution flag output control process performed in the torque correction execution determination part 8g of Example 5. It is a flowchart which shows the flow of the torque correction gain calculation control processing performed by the torque correction gain calculation part 8e of Example 5. It is a time chart which shows the steering force fluctuation | variation at the time of complete | finishing assist torque correction simultaneously with completion | finish of lane keeping control. 10 is a time chart illustrating an assist torque correcting operation according to a fifth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Handle 2 Torque sensor 3 Assist motor 3a Reducer 4 Motor position sensor 5 Camera 6 Yaw rate sensor 7 Vehicle speed sensor 8 Controller 8a Basic assist command value calculating part 8b Lane maintenance torque calculating part 8c Assist torque correction calculating part 8d Reverse assist torque calculating part 8e Torque correction gain calculation unit 8f Motor control unit 8g Torque correction execution determination unit 9 Steering shaft 10 Rack gears 11, 11 Front wheels

Claims (7)

A steering actuator that applies torque to a steering mechanism that steers steering wheels ;
Lane maintaining torque calculating means for calculating a lane maintaining torque for maintaining the vehicle near the center of the lane based on the positional relationship with the lane ;
An assist torque calculating means for calculating an assist torque for assisting steering based on the steering torque of the driver ;
Torque command value calculating means for calculating a torque command value by adding the lane keeping torque and the assist torque;
Actuator control means for driving the steering actuator based on the torque command value;
Torque correction means for correcting the assist torque in a direction to increase when the direction of the lane keeping torque is different from the direction of the steering torque ;
Lane keeping assist device characterized by comprising a. The lane keeping assist device according to claim 1,
The lane keeping assist device according to claim 1, wherein when the direction of the lane keeping torque is the same as the direction of the steering torque, the torque compensating means corrects the assist torque in a direction to decrease the assist torque. In the lane keeping assist device according to claim 1 or 2,
A reverse assist torque calculating means for calculating a reverse assist torque according to a differential value of the steering torque;
The torque command value calculation means calculates the torque command value by subtracting the reverse assist torque from an addition value of the lane keeping torque and the assist torque,
The lane keeping assist device, wherein the torque correcting means corrects the reverse assist torque based on a direction of the lane keeping torque and a direction of the steering torque. The lane keeping assist device according to any one of claims 1 to 3,
The torque correction means corrects the assist torque only when the steering speed of the steering wheel is equal to or higher than a predetermined value when the direction of the lane maintaining torque is different from the direction of the steering torque. . The lane keeping assist device according to any one of claims 1 to 4,
The lane keeping assist device, wherein the torque correcting means changes a correction amount of the assist torque according to a magnitude of the lane keeping torque. The lane keeping assist device according to any one of claims 1 to 4 ,
The lane keeping assist device, wherein the torque correcting means corrects the assist torque so that the lane keeping torque does not change when the direction of the lane keeping torque and the direction of the steering torque are the same. In the lane keeping assist device according to any one of claims 1 to 5 ,
The lane keeping assist device is characterized in that the torque correcting means continues the assist torque correction after the lane keeping control is finished until the direction of the change of the steering torque of the driver is reversed.

Images