JP6862837B2 - Vehicle control unit - Google Patents

Description

The present invention relates to the technical field of a vehicle control device.

These types of devices include, for example, (i) Lane Departure Prevention Control that applies braking force to each wheel to generate a yaw moment in the direction of avoiding deviation when the own vehicle is likely to deviate from the traveling lane. ii) The steering stability is determined based on the deviation between the turning yaw rate of the own vehicle and the target yaw rate, and when the steering stability deteriorates, the difference between the left and right driving force in the direction of ensuring the steering stability. It is a device capable of performing vehicle behavior stability control that generates a yaw moment due to the above, and is to prevent lane departure in order to prevent the vehicle behavior stability control from malfunctioning when the lane departure prevention control is started. A device for correcting the target yaw rate in vehicle behavior stability control has been proposed based on the target yaw moment (see Patent Document 1).

Patent No. 038223924

According to the above-mentioned background technique, in order to give priority to the lane departure prevention control, the target yaw rate in the vehicle behavior stability control is corrected to the side where the vehicle behavior stability control does not operate. Then, even in a situation where stable vehicle behavior control should be performed, lane departure prevention control is prioritized and vehicle behavior may become unstable.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle control device capable of suppressing the operation of vehicle behavior stabilization control caused by lane departure prevention control.

In order to solve the above problems, the vehicle control device of the present invention is a vehicle provided with a braking device, and (i) said the vehicle when there is a possibility that the vehicle deviates from the currently traveling lane. Lane departure prevention control (corresponding to the above-mentioned "lane departure prevention control") that controls the braking device so as to generate a first braking force that applies a first yaw moment in a direction that suppresses deviation from the traveling lane. (Ii) On condition that the amount of deviation between the estimated yaw rate estimated based on the steering angle and the vehicle speed and the actual yaw rate generated in the vehicle is equal to or greater than the first threshold value, the second direction is in the direction in which the vehicle behavior is stable. A second vehicle control device capable of performing vehicle behavior stability control that controls the braking device so as to generate a second braking force that applies a yaw moment, and the deviation amount is smaller than the first threshold value. When the value is equal to or higher than the threshold value, a control means for suppressing the execution of the lane departure prevention control is provided.

In the vehicle control device, when there is a possibility that vehicle behavior stability control is executed due to the execution of lane departure prevention control (that is, the amount of deviation between the estimated yaw rate and the actual yaw rate is equal to or greater than the second threshold value. In the case of), the implementation of the lane departure prevention control is suppressed. Therefore, according to the vehicle control device, it is possible to suppress the operation of the vehicle behavior stabilization control caused by the lane departure prevention control. In addition, when the deviation amount is less than the second threshold value, the lane departure prevention control can be implemented, so that the vehicle control device suppresses the deviation of the vehicle from the traveling lane.

The actions and other gains of the present invention will be apparent from the embodiments described below.

It is a block diagram which shows the structure of the vehicle which concerns on embodiment. It is a flowchart which shows the lane departure prevention operation which concerns on embodiment. It is a flowchart which shows the brake LDA suppression determination processing which concerns on embodiment. It is a figure which shows an example of the relationship between the deviation amount and the limit amount of the control amount which concerns on a brake LDA. This is an example of a timing chart when the brake LDA according to the embodiment is implemented. This is an example of a timing chart when the brake LDA according to the comparative example is implemented. It is a flowchart which shows the brake LDA suppression determination processing which concerns on a modification.

An embodiment according to the vehicle control device of the present invention will be described with reference to FIGS. 1 to 6. In the following embodiments, the description will proceed using the vehicle 1 equipped with the vehicle control device of the present invention.

(Vehicle configuration)
The configuration of the vehicle 1 will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a vehicle according to an embodiment.

In FIG. 1, the vehicle 1 includes a brake pedal 111, a master cylinder 112, a brake actuator 13, a wheel cylinder 122FL arranged on the left front wheel 121FL, and a wheel cylinder 122FR arranged on the left rear wheel 121RL. It includes a wheel cylinder 122RL arranged on the right front wheel 121FR, a wheel cylinder 122RR arranged on the right rear wheel 121RR, and brake pipes 113FL, 113RL, 113FR and 113RR.

The vehicle 1 further includes a brake control unit 14, a vehicle speed sensor 151, a wheel speed sensor 152, a steering angle sensor 153, a yaw rate sensor 154, an acceleration sensor 155, a camera 156, and a B-LDA ECU (Brake-). It includes a Lane Device Alart Electronic Control Unit 16, a VSC (Vehicle Sensory Control) ECU 17, and a display 18.

The master cylinder 112 adjusts the pressure of the brake fluid (or any fluid) in the master cylinder 112 according to the amount of depression of the brake pedal 111. The pressure of the brake fluid in the master cylinder 112 is transmitted to the wheel cylinders 122FL, 122RL, 122FR and 122RR via the brake pipes 113FL, 113RL, 113FR and 113RR, respectively. As a result, braking force corresponding to the pressure of the brake fluid transmitted to the wheel cylinders 122FL, 122RL, 122FR and 122RR is applied to the left front wheel 121FL, the left rear wheel 121RL, the right front wheel 121FR and the right rear wheel 121RR, respectively. ..

Under the control of the brake control unit 14, the brake actuator 13 can adjust the pressure of the brake fluid transmitted to each of the wheel cylinders 122FL, 122RL, 122FR and 122RR regardless of the amount of depression of the brake pedal 111. Therefore, the brake actuator 13 can adjust the braking force applied to each of the left front wheel 121FL, the left rear wheel 121RL, the right front wheel 121FR, and the right rear wheel 121RR, regardless of the amount of depression of the brake pedal 111.

The B-LDA ECU 16 performs lane departure prevention control for suppressing the deviation of the vehicle 1 from the traveling lane in which the vehicle is currently traveling. That is, the B-LDA ECU 16 functions as a control device for realizing so-called LDA or LDP (Lane Departure Prevention). The B-LDA ECU 16 includes a data acquisition unit 161 and an LDA control unit 162 as a processing block logically realized inside or as a processing circuit physically realized in order to perform lane departure prevention control. There is. The details of the lane departure prevention control will be described later.

The VSC ECU 17 performs vehicle behavior stabilization control to prevent the behavior of the vehicle 1 from becoming unstable due to, for example, skidding when the vehicle 1 turns. The VSC ECU 17 includes a data acquisition unit 171 and a VSC control unit 172 as a processing block that is logically realized or a processing circuit that is physically realized inside the vehicle in order to perform stable vehicle behavior control.

The VSC control unit 172 of the VSC ECU 17 deviates between the estimated yaw rate, which is the yaw rate estimated from the state of the vehicle 1 based on the detection data acquired by the data acquisition unit 171, and the actual yaw rate, which is the yaw rate actually generated in the vehicle 1. Find the amount. Specifically, the VSC control unit 172 calculates the estimated yaw rate based on, for example, the vehicle speed based on the detection result of the vehicle speed sensor 151 and the steering angle based on the detection result of the steering angle sensor 153. The VSC control unit 172 obtains the actual yaw rate based on, for example, the detection result of the yaw rate sensor 154. Then, the VSC control unit 172 obtains the amount of dissociation by calculating the difference between the estimated yaw rate and the actual yaw rate.

The VSC control unit 172 is in a direction in which the behavior of the vehicle 1 is stabilized on condition that the obtained deviation amount is equal to or greater than a predetermined VSC threshold value (corresponding to a specific example of the "first threshold value" according to the present invention). The brake actuator is applied via the brake control unit 14 so as to apply a braking force to at least one of the left front wheel 121FL, the left rear wheel 121RL, the right front wheel 121FR, and the right rear wheel 121RR in order to apply the yaw moment to the brake actuator. 13 is controlled.

Since various existing modes can be applied to the vehicle behavior stability control, the detailed description thereof will be omitted.

(Lane departure prevention operation)
Next, the lane departure prevention operation according to the present embodiment will be described.

1. 1. Outline of lane deviation suppression operation The LDA control unit 162 of the LDA ECU 16 has detection data acquired by the data acquisition unit 161 (that is, vehicle speed sensor 151, wheel speed sensor 152, steering angle sensor 153, yaw rate sensor 154, and acceleration sensor 155, respectively. Based on the data indicating the detection result) and the image data captured by the camera 156, it is determined whether or not the vehicle 1 may deviate from the traveling lane in which the vehicle 1 is currently traveling.

The LDA control unit 162 applies a suppression yaw moment capable of suppressing the deviation of the vehicle 1 to the vehicle 1 when there is a possibility of deviation, so that the left front wheel 121FL, the left rear wheel 121RL, the right front wheel 121FR and the right rear wheel A braking force is applied to at least one of 121RR. That is, in the present embodiment, the deviation from the traveling lane of the vehicle 1 is suppressed by using the difference between the left and right braking forces. Hereinafter, the "lane departure prevention" according to the present embodiment will be appropriately referred to as "brake LDA".

Here, "suppressing the deviation of the vehicle 1" means from the traveling lane when the suppressing yaw moment is applied to the vehicle 1 as compared with the deviation distance from the traveling lane when the suppressing yaw moment is not applied to the vehicle 1. It means to reduce the deviation distance of.

2. Problems caused by the brake LDA In the brake LDA, as described above, the deviation from the traveling lane of the vehicle 1 is suppressed by using the difference between the left and right braking forces. That is, in the brake LDA, the posture of the vehicle 1 is changed by the suppression yaw moment applied due to the difference in braking force between the left and right while the steering angle of the vehicle 1 is maintained.

Therefore, when the brake LDA is implemented, the estimated yaw rate estimated from the vehicle speed and the steering angle does not change at all or the actual yaw rate of the vehicle 1 increases. That is, when the brake LDA is implemented, the amount of deviation between the estimated yaw rate and the actual yaw rate increases. As a result, due to the implementation of the brake LDA, the vehicle behavior stabilization control can be easily implemented.

Therefore, in the present embodiment, the brake LDA and the vehicle behavior stabilization control are arbitrated in order to suppress the implementation of the vehicle behavior stabilization control.

3. 3. Details of Lane Departure Suppression Operation Next, details of the lane departure prevention operation according to the present embodiment will be described with reference to FIGS. 2 to 4.

In FIG. 2, first, the data acquisition unit 161 captures detection data showing the detection results of each of the vehicle speed sensor 151, the wheel speed sensor 152, the steering angle sensor 153, the yaw rate sensor 154, and the acceleration sensor 155, and the image captured by the camera 156. The indicated image data is acquired (step S101).

By analyzing the image data acquired in the process of step S101, the LDA control unit 162 sets a "white line" as an example of the lane end of the traveling lane in which the vehicle 1 is currently traveling (in the present embodiment, the "white line" is used as an example of the lane end. (Listed) is specified in the image captured by the camera 156 (step S102).

The LDA control unit 162 determines whether the traveling lane in which the vehicle 1 is currently traveling is a straight road or a curved road based on the white line specified in the process of step S102, and determines that the vehicle 1 is a curved road. If so, the radius of curvature of the traveling lane is calculated (step S103). The radius of curvature of the traveling lane is substantially equivalent to the radius of curvature of the white line. Therefore, the LDA control unit 162 may calculate the radius of curvature of the white line specified in the process of step S102, and treat the calculated radius of curvature as the radius of curvature of the traveling lane.

The LDA control unit 162 further calculates the current lateral position, lateral speed, and deviation angle of the vehicle 1 based on the white line specified in the process of step S102 (step S104). Here, the "horizontal position" is the distance from the center of the traveling lane to the vehicle 1 (typically, the center of the vehicle 1) along the lane width direction orthogonal to the direction in which the traveling lane extends (lane extending direction). Distance to). The "lateral speed" means the speed of the vehicle 1 along the lane width direction. The "deviation angle" means the angle formed by the traveling lane and the front-rear axis of the vehicle 1 (that is, the angle formed by the white line and the front-rear axis of the vehicle 1).

The LDA control unit 162 further sets an allowable deviation distance (step S105). The permissible deviation distance indicates the maximum permissible value of the deviation distance of the vehicle 1 from the traveling lane (that is, the deviation distance of the vehicle 1 from the white line) when the vehicle 1 deviates from the traveling lane. Therefore, the lane departure prevention operation is an operation of applying a suppression yaw moment to the vehicle 1 so that the deviation distance of the vehicle 1 from the traveling lane is within the allowable deviation distance.

The permissible deviation distance may be set as follows, for example. That is, the LDA control unit 162 may set the permissible deviation distance from the viewpoint of satisfying the requirements of laws and regulations (for example, the request of NCAP: New Car Assessment Program). The permissible deviation distance set from such a viewpoint may be used as the default permissible deviation distance. The method of setting the allowable deviation distance is not limited to this.

The LDA control unit 162 executes the brake LDA suppression determination (that is, arbitration between the brake LDA and the vehicle behavior stability control) in parallel with the process of step S105. Here, the brake LDA suppression determination will be described with reference to the flowchart of FIG.

In FIG. 3, the LDA control unit 162 acquires the detection data acquired by the data acquisition unit 161 in the process of step S101 (step S201). Next, the LDA control unit 162 acquires the actual yaw rate of the vehicle 1 as the actual turning state related to the vehicle 1 based on the detection result of the yaw rate sensor 154, for example (step S202).

The LDA control unit 162 determines the estimated yaw rate estimated from, for example, the vehicle speed based on the detection result of the vehicle speed sensor 151 and the steering angle based on the detection result of the steering angle sensor 153 in parallel with or before and after the process of step S202. Is acquired as the estimated turning state of the vehicle 1 (step S203).

After that, the LDA control unit 162 calculates the amount of deviation between the actual yaw rate and the estimated yaw rate (step S204). Next, the LDA control unit 162 determines whether or not the deviation amount is equal to or greater than a predetermined value (step S205). In this determination, when it is determined that the deviation amount is equal to or greater than a predetermined amount (step S205: Yes), the LDA control unit 162 suppresses the brake LDA (step S206).

On the other hand, when it is determined in the determination of step S205 that the deviation amount is less than a predetermined amount (step S205: No), the LDA control unit 162 limits the control amount related to the brake LDA (for example, the upper limit of the control amount). Value) is calculated (step S207). In addition, "the limit amount of the control amount concerning the brake LDA" is hereinafter referred to as "the limit amount of LDA" as appropriate. Specifically, as shown in FIG. 4, the LDA control unit 162 calculates the LDA limit amount by using an arithmetic expression such that the LDA limit amount becomes smaller as the dissociation amount becomes larger. Next, the LDA control unit 162 calculates the deviation determination condition according to the LDA limit amount (step S208).

The "predetermined value" according to the embodiment is an example of the "second threshold value" according to the present invention. As shown in FIG. 4, the “predetermined value” is a value smaller than the VSC threshold value. The "predetermined value" is a value for determining whether or not to suppress the brake LDA, and is set in advance as a fixed value or a variable value according to some physical quantity or parameter. For the "predetermined value", the maximum value of the suppression yaw moment that can be applied to the vehicle 1 by, for example, the brake LDA is obtained experimentally, empirically, or by simulation, and the maximum value of the suppression yaw moment is given to the vehicle 1. The amount of change in yaw rate may be obtained and set as a value obtained by subtracting the amount of change from the VSC threshold value.

Returning to FIG. 2 again, the LDA control unit 162 then determines whether or not the vehicle 1 may deviate from the currently traveling lane (step S106). Specifically, for example, the LDA control unit 162 calculates the future position of the vehicle 1 (for example, after a few seconds to a dozen seconds) based on the current speed, the lateral position, the lateral speed, and the like of the vehicle 1. Then, the LDA control unit 162 determines whether or not the vehicle 1 crosses or steps on the white line at a future position. If it is determined that the vehicle 1 crosses or steps on the white line at a future position, the LDA control unit 162 determines that the vehicle 1 may deviate from the traveling lane.

When it is determined in step S106 that the vehicle 1 is unlikely to deviate from the traveling lane (step S106: No), the lane departure prevention operation shown in FIG. 2 is terminated. After that, the LDA control unit 162 starts the lane departure prevention operation shown in FIG. 2 again after a predetermined period (for example, several milliseconds to several tens of milliseconds) has elapsed. That is, the lane departure prevention operation shown in FIG. 2 is repeatedly performed at a cycle corresponding to a predetermined period.

On the other hand, when it is determined in the determination of step S106 that the vehicle 1 may deviate from the traveling lane (step S106: Yes), the LDA control unit 162 turns on the control flag related to the brake LDA and turns on the control flag. , Warns the driver of the vehicle 1 that the vehicle 1 may deviate from the traveling lane (step S107). Specifically, the LDA control unit 162 controls the display 18 so as to display, for example, an image showing that the vehicle 1 may deviate from the driving lane, and / or the vehicle 1 is from the driving lane. Vibrate the steering wheel (not shown) that it may deviate.

When it is determined that the vehicle 1 may deviate from the traveling lane, the LDA control unit 162 determines whether or not the brake LDA is suppressed in parallel with or before and after the process of step S107. (Step S108). In this determination, when it is determined that the brake LDA is suppressed (step S108: Yes), the lane departure prevention operation shown in FIG. 2 is terminated. After that, the LDA control unit 162 starts the lane departure prevention operation shown in FIG. 2 again after the predetermined period has elapsed.

On the other hand, when it is determined in the determination of step S108 that the brake LDA is not suppressed (step S108: No), the LDA control unit 162 is such that the vehicle 1 traveling away from the center of the traveling lane is traveling. Calculate a new travel locus that will drive toward the center of the lane. At this time, the calculated travel locus satisfies the constraint of the allowable deviation distance set in the process of step S105 and the LDA limit amount calculated in the process of step S207.

Next, the LDA control unit 162 should generate the vehicle 1 in order to avoid deviation from the traveling lane of the vehicle 1 (that is, to make the vehicle 1 travel along the calculated traveling locus). The yaw rate is calculated as the target yaw rate (step S109). Subsequently, the LDA control unit 162 calculates the yaw moment to be applied to the vehicle 1 as the target yaw moment in order to generate the target yaw rate in the vehicle 1 (step S110).

Here, the LDA control unit 162 may calculate the target yaw moment by converting the target yaw rate into the target yaw moment based on, for example, a predetermined conversion function. The target yaw moment is equivalent to the suppressed yaw moment described above.

Subsequently, the LDA control unit 162 calculates a braking force capable of applying a target yaw moment to the vehicle 1. At this time, the LDA control unit 162 individually calculates the braking force applied to each of the left front wheel 121FL, the left rear wheel 121RL, the right front wheel 121FR, and the right rear wheel 121RR.

Next, the brake control unit 14 calculates a pressure command value that specifies the oil pressure required to generate the braking force calculated by the LDA control unit 162 (step S111). At this time, the brake control unit 14 individually calculates a pressure command value that specifies the oil pressure inside each of the wheel cylinders 122FL, 122RL, 122FR, and 122RR.

Subsequently, the brake control unit 14 controls the brake actuator 13 based on the pressure command value calculated in the process of step S111. As a result, the braking force according to the pressure command value is applied to at least one of the left front wheel 121FL, the left rear wheel 121RL, the right front wheel 121FR, and the right rear wheel 121RR (step S112).

(Technical effect)
1. 1. When the brake LDA is suppressed In the present embodiment, when the amount of deviation between the estimated yaw rate estimated from the steering angle and the vehicle speed of the vehicle 1 and the actual yaw rate actually generated in the vehicle 1 is equal to or more than a predetermined amount, the brake LDA Is suppressed. In this case, the amount of deviation between the estimated yaw rate and the actual yaw rate does not increase due to the brake LDA. Therefore, since the brake LDA and the vehicle behavior stabilization control are not executed at the same time, it is possible to suppress the vehicle behavior stabilization control from being implemented.

2. When the brake LDA is permitted The technical effect when the brake LDA is permitted will be specifically described with reference to FIGS. 5 and 6. FIG. 5 is an example of a timing chart when the brake LDA according to the embodiment is implemented. FIG. 6 is an example of a timing chart when the brake LDA according to the comparative example is implemented.

At time t1 in FIG. 5, it is assumed that the vehicle 1 starts skidding due to, for example, a crosswind. As a result, although the steering angle has not changed, the actual turning amount increases due to the yaw rate generated in the vehicle 1. At this time, the amount of deviation between the estimated turning amount (that is, the estimated yaw rate estimated from the steering angle and the vehicle speed) and the actual turning amount also increases, so that the LDA limit amount is lowered by the process of step S207 (FIG. 5). See dashed line).

In FIG. 5, for convenience, it is assumed that the actual turning amount due to skidding is constant after the time t2. At time t3 in FIG. 5, it is assumed that the vehicle 1 may deviate from the traveling lane in the determination in step S106, and the control flag related to the brake LDA is turned on. By executing the brake LDA during the period from the time t3 to the time t4 in FIG. 5, the control amount related to the brake LDA increases.

As shown in FIG. 5, since the control amount related to the brake LDA is set to be equal to or less than the LDA limit amount, an increase in the actual turning amount due to the brake LDA is suppressed. Therefore, it is prevented that the deviation amount becomes equal to or larger than the VSC threshold value during the period when the brake LDA is performed (that is, from time t3 to time t4). That is, in the present embodiment, even when the brake LDA is permitted, the LDA limit amount is set according to the deviation amount, so that the brake LDA and the vehicle behavior stabilization control are not implemented at the same time. .. Therefore, in this case as well, it is possible to suppress the implementation of vehicle behavior stability control.

Also in the comparative example shown in FIG. 6, it is assumed that the vehicle starts skidding due to, for example, a crosswind at time t11. Then, at time t13, it is assumed that the control flag related to the brake LDA is turned on.

In the comparative example, the LDA limit amount is constant regardless of the amount of deviation before the brake LDA is performed.
By executing the brake LDA during the period from the time t13 to the time t14 in FIG. 6, the control amount related to the brake LDA increases. Although the controlled amount is equal to or less than the LDA limit amount, the LDA limit amount is relatively large, so that the controlled amount is also relatively large. As a result, during the period when the brake LDA is performed (that is, from time t13 to time t14), the actual turning amount may become relatively large, and the deviation amount may become larger than the VSC threshold value. Then, the brake LDA and the vehicle behavior stabilization control will be implemented at the same time.

The “LDA control unit 162” according to the embodiment is an example of the “control means” according to the present invention. The "B-LDA ECU 16" and the "VSC ECU 17" according to the embodiment are examples of the "vehicle control device" according to the present invention.

<Modification example>
In the above-described embodiment, when the dissociation amount is less than a predetermined value, the LDA limit amount is set according to the dissociation amount (see the flowchart of FIG. 3). However, as shown in the flowchart of FIG. 7, whether or not the brake LDA is suppressed may be simply determined depending on whether or not the amount of deviation is equal to or greater than a predetermined value.

The present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of claims and within a range not contrary to the gist or idea of the invention that can be read from the entire specification, and the vehicle control device accompanied by such a modification. Is also included in the technical scope of the present invention.

1 ... Vehicle, 13 ... Brake actuator, 14 ... Brake control unit, 16 ... B-LDA
ECU, 17 ... VSC ECU, 111 ... Brake pedal, 112 ... Master cylinder, 122FL, 122RL, 122FR, 122RR ... Wheel cylinder, 161, 171 ... Data acquisition unit, 162 ... LDA control unit, 172 ... VSC control unit

Claims (1)

In a vehicle equipped with a braking device, (i) when the vehicle may deviate from the currently traveling lane, a first yaw moment is applied in a direction of suppressing the deviation of the vehicle from the traveling lane. Lane departure prevention control that controls the braking device so as to generate the first braking force, and (ii) the amount of deviation between the estimated yaw rate estimated based on the steering angle and the vehicle speed and the actual yaw rate generated in the vehicle. The vehicle behavior stabilization control that controls the braking device so as to generate a second braking force that applies a second yaw moment in a direction in which the vehicle behavior stabilizes is carried out on condition that is equal to or higher than the first threshold value. A possible vehicle control device
A vehicle control device comprising: a control means for suppressing the execution of the lane departure prevention control when the deviation amount is equal to or greater than a second threshold value smaller than the first threshold value.

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