JP2011230666A - Apparatus and method for supporting narrow-road traveling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prompt a driver to perform intuitive proper steering operation when traveling on a narrow road.SOLUTION: Sonars 11L and 11R detect distances yand yto road boundaries to determine whether narrow-road support control is required, on the basis of detection results (S103). When the control is required, control is applied to a final torque control value If to support steering operation (S105). The final torque command value If is calculated by adding an avoidance torque command value Ia to an assist torque command value Is (S205). The avoidance torque command value Ia serves as a support torque in a direction away from the road boundary. The assist torque command value Is serves as a support torque in the direction same as the driver's steering direction. If the driver is steering to the road boundary, the assist torque command value Is is reduced to prevent approaching the road boundary.

Description

  The present invention relates to a narrow road driving support device and a narrow road driving support method.

  When traveling on a narrow road, the stereo imaging system recognizes the narrow road, determines whether the vehicle can pass without touching an obstacle, and installs it on the front fender according to the determination result. Some of the green, yellow, and red lamps are turned on (see Patent Document 1).

JP-A-9-106500

However, it is difficult for the driver to understand what kind of steering operation is required, including the operation direction, the operation amount, the operation timing, and the like only by displaying whether or not the host vehicle is in contact with an obstacle.
An object of the present invention is to intuitively prompt a driver to perform an appropriate steering operation when traveling on a narrow road.

  The narrow road driving support device according to the present invention can apply a support torque to the driver's steering operation, detects the distance from the own vehicle to the left and right road boundary, and according to the detected distance to the road boundary The driver is urged to perform an avoidance operation from the boundary of the road to be avoided by performing control intervention on the assist torque while determining that the vehicle is traveling on a narrow road.

  According to the narrow road driving support device according to the present invention, when traveling on a narrow road, the distance from the own vehicle to the left and right road boundary is detected, and the support torque is determined according to the detected distance to the road boundary. By intervening control, the driver can intuitively urge the driver to perform appropriate steering operations when driving on narrow roads by prompting the driver to perform avoidance operations from the road boundary to be avoided. it can.

It is a schematic block diagram of a steering assistance system. It is a block diagram which shows a motor control process. It is a flowchart which shows a motor control process. It is a flowchart which shows a control intervention judgment process. The block diagram which shows narrow-path assistance control intervention processing is shown. It is a flowchart which shows a narrow road assistance control intervention process. It is a flowchart which shows a feedback deviation calculation process. It is a flowchart which shows an avoidance torque command value calculation process. It is a flowchart which shows an assist torque command value correction process. It is a map used for calculation of the correction coefficient k. It is the figure which showed an example of the driving | running | working scene.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
"Constitution"
FIG. 1 is a schematic configuration diagram of a steering assist system.
A sonar sensor 11L provided on the left side of the front side of the host vehicle 10 detects a distance y _L to a side object such as a wall, guardrail, or fence existing on the left side of the host vehicle 10 and supplies the detected distance y _L to the controller 12. input. The sonar sensor 11R provided on the front right side of the host vehicle 10 detects a distance y _R to a side object such as a wall, guardrail, or fence existing on the right side of the host vehicle 10 and the detected distance y _R is a controller. 12 is input. The torque sensor 14 detects the steering torque T of the driver acting on the steering shaft 15 and inputs the detected steering torque T to the controller 12. The steering angle sensor 17 detects the steering angle θ of the steering wheel 16 and inputs the detected steering angle θ to the controller 12. The vehicle speed sensor 18 detects the host vehicle speed V and inputs the detected vehicle speed V to the controller 12.

  The steering angle sensor 17 outputs a detected value as a negative value when the steering angle θ is in the left turn region, and outputs a detected value as a positive value when the steering angle θ is in the right turn region. The torque sensor 14 outputs a detected value as a negative value when the steering torque T is in the left turn direction, and outputs a detected value as a positive value when the steering torque T is in the right turn direction.

  The controller 12 is composed of, for example, a microcomputer, and drives and controls the electric motor 13 for electric power steering based on various input signals. Here, although the electric power steering apparatus has been described, a steering-by-wire configuration capable of mechanically separating the steering wheel 16 and the wheel may be used. The hydraulic power steering apparatus may be configured to perform hydraulic control using an electric motor as a drive source.

FIG. 2 is a block diagram showing motor control processing.
The controller 12 includes a control intervention determination unit 19, an assist torque command value calculation unit 20, and a narrow road support control intervention unit 21.
The control intervention determination unit 19 includes distances y _L and y _R to the side objects detected by the sonars 11L and 11R, a steering angle θ detected by the steering angle sensor 17, a vehicle speed V detected by the vehicle speed sensor 18, and Is entered. The control intervention determination unit 19 determines whether or not to start narrow road support control for prompting the driver to perform a steering operation in a direction away from the side object, based on the various signals input.

  The steering torque T detected by the torque sensor 14 and the vehicle speed V detected by the vehicle speed sensor 18 are input to the assist torque command value calculation unit 20. The assisting torque command value calculation unit 20 performs the same calculation as that of a general electric power steering device, and based on various input signals, a current command value for realizing a normal EPS assist torque is determined as an assisting torque command value Is. Calculate as

The narrow road support control intervention unit 21 includes a determination result of the control intervention determination unit 19, a calculation result of the assist torque command value calculation unit 20, and distances y _L and y _R to the side objects detected by the sonars 11L and 11R. And the steering angle θ detected by the rudder angle sensor 17 are input. The narrow road support control intervention unit 21 calculates a final current command value for the electric motor 13 as a final torque command value If based on various input signals, and the electric motor 13 according to the calculated final torque command value If. Is controlled.

FIG. 3 is a flowchart showing the motor control process.
The controller 12 executes a motor control process at every predetermined calculation cycle.
First, in step S101, various signals are read and stored in the memory.
In the subsequent step S102, the assist torque command value calculation unit 20 executes assist torque command value calculation processing, and calculates an assist torque command value Is for realizing a normal EPS assist torque according to the steering torque T and the vehicle speed V. .

  In the subsequent step S103, the control intervention determination unit 19 executes control intervention determination processing, and executes a subroutine for determining whether or not to perform narrow road support control for prompting the driver to perform a steering operation in a direction away from the side object. To do. The determination result is acquired as a narrow road support flag f.

  In a succeeding step S104, the setting state of the narrow road support flag f is determined. Here, if the narrow road support flag is set to “f = 1”, it is determined that the narrow road support control is necessary, and the process proceeds to step S105. On the other hand, if the narrow road support flag is reset to “f = 0”, it is determined that the narrow road support control is unnecessary, and the process proceeds to step S106.

In step S105, the narrow road assistance control intervention section 21 executes narrow road assistance control intervention processing, calculates the final torque command value If for realizing the assist torque in the direction away from the side object, and then proceeds to step S107. To do.
In step S106, the assist torque command value Is for realizing the assist torque as normal steering assistance is used as it is as the final torque command value, and then the process proceeds to step S107.
In step S107, the electric motor 13 is driven and controlled according to the final torque command value If, and then the process returns to a predetermined main program.

FIG. 4 is a flowchart showing the control intervention determination process.
The controller 12 executes control intervention determination processing by the control intervention determination unit 19 as a subroutine of step S103 described above.

First, in step S601, various signals are read.
In the subsequent step S602, it is determined whether or not the sum S of the distance y _L to the left side object and the distance y _R to the right side object is equal to or less than a preset first threshold th1. . Here, if the determination result is “S ≦ th1”, it is determined that the vehicle is traveling on a narrow road and it is necessary to prompt an appropriate steering operation to the left and right side objects, and the process proceeds to step S603. On the other hand, if the determination result is “S> th1”, it is determined that it is necessary to prompt an appropriate steering operation only for the left and right side objects, and the process proceeds to step S607 described later.

In step S603, the distance y _L to the left side object and the distance y _R to the right side object are compared to determine which is greater. Here, if the determination result is “y _L ≦ y _R ”, it is determined that an avoidance operation for the left side object is necessary, and the process proceeds to step S604. On the other hand, if the determination result is “y _L > y _R ”, it is determined that an avoidance operation for the right side object is necessary, and the process proceeds to step S606.

In step S604, the control mode is set as “both sides support / left object avoidance”, and the narrow road support flag is set to “f = 1”.
In subsequent step S605, the control mode information and the narrow path support flag information are output, and then the control intervention determination process is terminated.
In step S606, the control mode is set as “both sides support / right object avoidance” and the narrow road support flag is set to “f = 1”, and then the process proceeds to step S605.

On the other hand, in step S607, it is determined whether the distance y _L to the left side object is smaller than a predetermined second threshold th2 and the steering angle θ is a negative value corresponding to the left turn area. . Here, if the determination result is “y _L <th2 and θ <0”, it is determined that the vehicle is traveling on a narrow road and an avoidance operation is required for the left side object, and the process proceeds to step S608. On the other hand, if the determination result is “y _L ≧ th2 or θ ≧ 0”, it is determined that the avoidance operation for the left side object is unnecessary, and the process proceeds to step S609.

In step S608, the control mode is set as “one-side assistance / left object avoidance” and the narrow road assistance flag is set to “f = 1”, and then the process proceeds to step S605.
In step S609, it is determined whether the distance y _R to the right side object is smaller than a predetermined second threshold th2 and the steering angle θ is a positive value corresponding to the right turn region. Here, if the determination result is “y _R <th2 and θ> 0”, it is determined that the vehicle is traveling on a narrow road and an avoidance operation for the right side object is necessary, and the process proceeds to step S610. On the other hand, if the determination result is “y _R ≧ th2 or θ ≦ 0”, it is determined that the avoidance operation for the right side object is unnecessary, and the process proceeds to step S611.

In step S610, the control mode is set as “one-side assistance / right object avoidance” and the narrow road assistance flag is set to “f = 1”, and then the process proceeds to step S605.
In step S611, the narrow road support flag is reset to “f = 0”, and then the process proceeds to step S605.

FIG. 5 is a block diagram showing the narrow road support control intervention process.
The narrow road assistance control intervention unit 21 includes a feedback deviation calculation unit 22, an avoidance torque command value calculation unit 23, a rate limiter 24, an assist torque command value correction unit 25, and an adder 26.

The feedback deviation calculation unit 22 receives the distances y _L and y _R to the side objects detected by the sonars 11L and 11R and the determination result of the control intervention determination unit 19. The feedback deviation calculation unit 22 calculates, for example, the deviation between the current distances y _L and y _R and the reference value C as the feedback deviation e when the narrow road support flag is set to “f = 1”. Therefore, when the host vehicle approaches the side object and the current distances y _L and y _R leave the reference value C, the feedback deviation e increases.

The avoidance torque command value calculation unit 23 includes a calculation result of the feedback deviation calculation unit 22, distances y _L and y _R to the side objects detected by the sonars 11L and 11R, a determination result of the control intervention determination unit 19, and Is entered. The avoidance torque command value calculation unit 23 calculates, as the avoidance torque command value Ia, a value obtained by multiplying the feedback deviation by the proportional gain K by, for example, a proportional feedback method. The avoidance torque command value Ia is a torque in a direction away from the side object, and increases as the distance to the side object decreases.

  The calculation result of the avoidance torque command value calculation unit 23 and the determination result of the control intervention determination unit 19 are input to the rate limiter 24. The rate limiter 24 limits the magnitude of the fluctuation rate in order to prevent a sudden change in the avoidance torque command value Ia when the narrow road support flag changes or when the control mode changes. For example, it may be realized by LPF (Low-Pass Filter), or an avoidance torque command value Ia for smoothly connecting the current value and the target value may be calculated.

  The assist torque command value correction unit 25 receives the calculation result of the assist torque command value calculation unit 20, the steering angle θ detected by the steering angle sensor 17, and the determination result of the control intervention determination unit 19. The assist torque command value correction unit 25 holds the steering angle θ when the narrow road support flag changes from “f = 0” to “f = 1” in the memory as the intervention start steering angle θs, and thereafter, intervention start steering. When the steering angle θ increases to the side of the side object with respect to the angle θs, the assist torque command value Is is corrected to decrease according to a predetermined map. Specifically, the assisting torque command value Is calculated by the assisting torque command value calculating unit 20 is multiplied by a correction coefficient k in the range of 0 to 1 to reduce and correct the assisting torque command value Is. Therefore, if the driver performs a steering operation on the side approaching the side object after the narrow road support flag changes to “f = 1”, the assist torque to the side of the side object decreases, and the side The weight is increased with respect to the steering operation toward the side object.

  The adder 26 calculates the final torque command value If by adding the avoidance torque command value Ia processed by the rate limiter 24 and the assisting torque command value Is corrected by the assisting torque command value correcting unit 25.

FIG. 6 is a flowchart showing a narrow road support control intervention process.
The controller 12 executes narrow road support control intervention processing by the narrow road support control intervention unit 21 as a subroutine of step S105 described above.

In step S201, it executes the feedback deviation calculation processing by the feedback deviation calculation unit 22 calculates the difference between the current distance y _L and y _R and a preset reference value C as a feedback error e.
In subsequent step S202, the avoidance torque command value calculation unit 23 executes the avoidance torque command value calculation process, and calculates the avoidance torque command value Ia by multiplying the feedback deviation e by the proportional gain K.

In subsequent step S203, the rate limiter 24 limits the change rate of the avoidance torque command value Ia when the narrow road support flag changes or when the control mode changes. For example, an LPF with a time constant of about 1 second is used.
In subsequent step S204, the assisting torque command value correcting unit 25 executes assisting torque command value correction processing, and the assisting torque command value Is is multiplied by a correction coefficient k in the range of 0 to 1, thereby obtaining an assisting torque command value. The value Is is corrected to decrease.

In the subsequent step S205, the adder 26 adds the avoidance torque command value Ia processed in step S203 and the assist torque command value Is corrected in step S204, and calculates the final torque command value If. The narrow road support control intervention process is terminated.
FIG. 7 is a flowchart showing feedback deviation calculation processing.
The controller 12 executes a feedback deviation calculation process by the feedback deviation calculation unit 22 as a subroutine of step S201 described above.

First, in step S301, a preset default reference value C is read. For example, C = about 100 cm.
In a succeeding step S302, it is determined whether or not the control mode is “one side support”. If the control mode is set to “one side support”, the process proceeds to step S303. On the other hand, if the control mode is set to “both sides support”, the process proceeds to step S304.

In step S303, as shown in the following equation (1), the feedback deviation e is calculated based on the difference between the reference value C and the distance y ₁ to either one of the left and right side objects selected. Here, y ₁ is either one of the distances y _L and y _{R to} the left and right side objects selected according to the control mode. That is, if the control mode is set to “left object avoidance”, the distance y _L to the left side object is selected as y ₁ , and if the control mode is set to “right object avoidance” The distance y _R to the right side object is selected as y ₁ .

e = C-y ₁ (1)
In step S304, as shown in the following equation (2), the reference value C, the distance y1 to _one of the left and right selected side objects, and the distance to the other side object of the left and right depending on the y _2, calculates a feedback error e. Here, y ₁ is _one of the distances y _L and y _{R to} the left and right side objects selected according to the control mode, and y ₂ is the distance to the left and right side objects. of distance y _L and y _R, which is the other of a distance that is not selected as y _1. That is, if the control mode is set to “left object avoidance”, the distance y _L to the left side object is selected as y ₁ and the distance y _R to the right side object is selected as y ₂ To do. On the other hand, if the control mode is set to “right object avoidance”, the distance y _R to the right side object is selected as y ₁ and the distance y _L to the left side object is selected as y _2. To do. {(Y ₂ + y ₁ ) / 2} is the center position between the left side object and the right side object, that is, the width center position of the narrow path.

It should be noted that, for a short period after the control mode changes between “one-side support” and “two-side support”, as shown in the following equation (3), either the reference value C or the left or right is selected. The feedback deviation e is calculated according to the distance y ₁ to one side object and the distance y ₂ to the other left / right side object. Here, {(y ₂ −y ₁ ) / (y ₁ + y ₂ )} is a ratio of the amount of bias (y ₂ −y ₁ ) to one side with respect to the total left and right margin (y _L + y _R ) of the vehicle. Become.

  Further, the feedback deviation may be calculated using not only the above formulas (1) to (3) but also a map having the same concept. That is, in the case of the both-side wall control mode, an amount arbitrarily converted based on the deviation with respect to the center position of the narrow road width may be used as the feedback deviation.

FIG. 8 is a flowchart showing avoidance torque command value calculation processing.
The controller 12 performs avoidance torque command value calculation processing by the avoidance torque command value calculation unit 23 as a subroutine of step S202 described above.
First, in step S401, a preset default gain Kd is read.
In a succeeding step S402, it is determined whether or not the control mode is “one side support”. If the control mode is set to “one side support”, the process proceeds to step S403. On the other hand, if the control mode is set to “both sides support”, the process proceeds to step S405.

In step S403, the default gain Kd is set as the feedback gain K.
In the subsequent step S404, a value obtained by multiplying the feedback deviation e by the feedback gain K is calculated as the avoidance torque command value Ia, and then the avoidance torque command value calculation process is terminated.

In step S405, as shown in the following equation (4), the reference value C, the default gain Kd, the distance y1 to _one of the left and right selected side objects, and the other of the left and right The feedback gain K is calculated according to the distance y ₂ to the side object. Here, α is an arbitrary design parameter.

  Although P control is used, any other feedback controller may be used to calculate the avoidance torque command value Ia. For example, PID control may be used, or a controller using a model such as optimal control. Design may be performed.

FIG. 9 is a flowchart showing assist torque command value correction processing.
The controller 12 executes assist torque command value correction processing by the assist torque command value correction unit 25 as a subroutine of S204 described above.
First, in step S501, the current steering angle θ is read.
In the subsequent step S502, it is determined whether or not the narrow road support flag has changed from “f = 0” to “f = 1”. If the narrow road support flag has just changed to “f = 1”, the process proceeds to step S503. On the other hand, if the narrow road support flag is not immediately after “f = 1”, the process proceeds to step S504.

In step S503, the current steering angle θ is held in the memory as the intervention start steering angle θs.
In a succeeding step S504, it is determined whether or not the direction of the steering torque T is coincident with the side of the side object to be avoided. That is, if the control mode is set to “left object avoidance”, it is determined whether or not the steering torque T is a negative value corresponding to the left turn direction, and the control mode is set to “right object avoidance”. If it is, it is determined whether or not the steering torque T is a positive value corresponding to the right turn direction. Here, if the steering torque T is suitable for avoidance, it is determined that the assist torque command value Is needs to be corrected to decrease, and the process proceeds to step S505. On the other hand, if the steering torque T is not suitable for avoidance, it is determined that the assist torque command value Is does not need to be corrected to decrease, and the process proceeds to step S507.

In the subsequent step S505, the correction coefficient k is calculated according to the difference Δθ between the current steering angle θ and the intervention start steering angle θs with reference to the map of FIG.
FIG. 10 is a map used for calculating the correction coefficient k.
The difference Δθ is calculated by subtracting the intervention start steering angle θs from the steering angle θ if the control mode is set to “left object avoidance”, and the control mode is set to “right object avoidance”. For example, it is calculated by subtracting the steering angle θ from the intervention start steering angle θs. That is, when the difference Δθ is a negative value, it indicates that the steering operation is being performed on the side to be avoided from the time when the narrow road support control is started, and when the difference Δθ is a positive value, the narrow road support control is started. This indicates that the steering operation is performed on the opposite side of the avoidance target from the point of time.

When the difference Δθ is in the region of 0 or more, the correction coefficient k remains 1, and the correction coefficient k decreases in the range of 1 to 0 as shown by the characteristic line _L 1 as it becomes smaller than 0. Further, as indicated by characteristic lines _L2 and _L3 , the difference Δθ decreases as the vehicle speed V increases, the decrease rate of the distance to the side object increases, and the distance to the side object decreases. The reduction rate of the correction coefficient k is set to be high. In addition, the steering angle at which the correction coefficient k starts to decrease from 1 may be set on the opposite side of the avoidance target with respect to the intervention start steering angle θs. Moreover, you may set the characteristic lines L1-L3 to arbitrary shapes.

In subsequent step S506, as shown in the following equation (5), the assisting torque command value Is is corrected by multiplying the assisting torque command value Is by the correction coefficient k, and then the assisting torque command value correcting process is terminated.
Is ← Is × k ............ (5)
In step S507, as shown in the following equation (6), the correction coefficient k is set to 1, and then the process proceeds to step S506.

    k = 1 ............ (6)

<Action>
First, an assist torque command value Is for the driver's steering operation is calculated (S102), and the electric motor 13 is driven and controlled using the assist torque command value Is as a final torque command value If (S106, S107). Since the assist torque command value Is has the same assist torque as the driver's steering direction, the driver's steering burden is reduced.

By the way, when driving on a narrow road, if the driver's steering operation is not appropriate, the host vehicle may come into contact with the left and right side objects.
FIG. 11 is a diagram illustrating an example of a traveling scene.

  It is assumed that the host vehicle is traveling on a narrow road sandwiched between a left road boundary 30 and a right road boundary 31. Here, the runway boundaries 30 and 31 are assumed to be side objects such as walls, guardrails, and fences. When traveling on such a narrow road, in order to intuitively prompt an appropriate steering operation with respect to the left and right road boundary, control intervention is performed on the assist torque of the electric motor 13 to perform steering support.

First, the sonars 11L and 11R detect the distances y _L and y _R with respect to the road boundary, and determine whether or not the intervention of narrow road support control is necessary according to the detection result (S103).
Here, the running road during running, when the sum S of the left distance y _L and the right distance y _R is a narrow passage which is a first threshold value th1 or less (the determination in S602 "Yes"), the control The mode is set to “Both sides support”. In this case, when the host vehicle is approaching the left side of the narrow road (the determination in S603 is “Yes”), it is determined that an avoidance operation is necessary for the left road boundary 30, and the control mode is “left object. “Avoid” ”is set (S604). On the other hand, when the host vehicle is approaching the right side of the narrow road (determination in S603 is “No”), it is determined that an avoidance operation is necessary for the right road boundary 31, and the control mode is “right object avoidance”. ] Is set (S605).

The running road during running, the sum S of the left distance y _L and the right distance y _R is assumed to be traveling path which is a first threshold value th1 (the determination in S602 "No"). In this case, when the left distance y _L is less than the second threshold th2 and the steering angle θ is in the left turn region (determination in S607 is “Yes”), the avoidance operation is performed on the left track boundary 30. Is determined to be necessary, and the control mode is set to “one side support / left object avoidance” (S608). On the other hand, when the right distance y _R is less than the second threshold th2 and the steering angle θ is in the right turn area (determination in S609 is “Yes”), an avoidance operation is performed on the right track boundary 31. Is determined to be necessary, and the control mode is set to “one-side assistance / right object avoidance” (S610).

Incidentally, the distance y _L to the left side of the lane boundary 30, if greater than the distance y _R are both second threshold th2 to right lane boundary 31 (S607 and S609 of the determination are both "No"), It is determined that no avoidance operation is required on either of the left and right sides, and that the narrow road support control is unnecessary (S611).
In this way, it is determined whether or not the narrow road support control is necessary, and if it is determined that the control intervention is necessary, the control intervention is performed for the final torque command value If and the steering support is performed (S105).

  Here, the final torque command value If is calculated by adding the avoidance torque command value Ia and the assist torque command value Is (S205). The avoidance torque command value Ia is a support torque in a direction away from the road boundary. On the other hand, the assist torque command value Is is the same assist torque as the driver's steering direction. Therefore, if the driver's steering direction is toward the road boundary, the assist torque command value Is is corrected to decrease. Access to the track boundary is suppressed. That is, the assisting torque is weakened and the steering operation becomes heavy for the driver, so that approach to the road boundary is suppressed. Thus, control intervention is performed on the final torque command value If by increasing the avoidance torque command value Ia and decreasing the assist torque command value Is. Therefore, the generation amount of the avoidance torque command value Ia (the increase amount from 0) and the decrease amount of the assist torque command value Is when the driver's steering direction is toward the road boundary are controlled by the narrow road support control. The amount of intervention.

  Thus, by calculating the final torque command value If by adding the avoidance torque command value Ia and the assist torque command value Is, approach to the road boundary on the avoidance target side is suppressed or separation is promoted. . That is, when the avoidance torque command value Ia and the assist torque command value Is have different signs (directions), if the absolute value of the avoidance torque command value Ia is smaller than the absolute value of the assist torque command value Is, the avoidance target side If the approach to the road boundary is suppressed and the absolute value of the avoidance torque command value Ia is larger than the absolute value of the assist torque command value Is, the separation from the road boundary on the side to be avoided is promoted. In addition, when the avoidance torque command value Ia and the assist torque command value Is have the same sign (direction), separation from the avoidance target side traveling path boundary is always promoted.

First, the avoidance torque command value Ia is calculated by multiplying the feedback deviation e and the feedback gain K (S404).
Here, when the control mode is “one-side support” (determination in S302 is “Yes”), the difference between the default reference value C and the distance y ₁ on the avoidance target side is fed back by the equation (1). The deviation e is calculated (S303). Accordingly, the avoidance torque command value Ia increases as the distance y ₁ on the avoidance target side is smaller, that is, the closer the host vehicle amount is to the avoidance target, and thus the avoidance operation can be urged more reliably to the driver. .

When the control mode is “both sides support” (the determination in S302 is “No”), unlike the case of “one side support”, the vehicle is centered in the width direction of the travel path according to the equation (2). The difference between the distance {(y ₂ + y ₁ ) / 2} from the road boundary at the time of the position and the distance y ₁ on the avoidance target side is calculated as a feedback deviation e (S304). That is, if the difference between the reference value C and the distance y ₁ is calculated as the feedback deviation e as in “one-side assistance”, for example, the reference value C is 100 cm and the vehicle left and right margin (y _L + y _R This is because there is a possibility that the steering wheel is cut too much toward the road boundary on the side opposite to the avoidance target in the case of a narrow road in which) is less than 200 cm. Therefore, in the case of “bilateral support”, in order to suppress the increase of the feedback deviation e than in the case of “single side support”, the calculation formula of the feedback deviation e is switched to suppress the avoidance torque command value Ia from becoming too large. .

In addition, for a short period after the control mode changes from “bilateral support” to “single side support” or from “single side support” to “bilateral support”, The ratio of the amount of deviation (y ₂ −y ₁ ) to one side with respect to the total margin amount (y _L + y _R ) is multiplied by the default reference value C to be calculated as a feedback deviation e. According to this arithmetic expression, when switching between “one-side support” and “two-side support”, it is possible to smoothly connect at the time of transition to the control mode.

As described above, by switching the calculation formula of the feedback deviation e, the feedback deviation e becomes larger and the avoidance torque command value Ia becomes larger when the control mode is “one-side assistance” than when the control mode is “two-side assistance”. Become. That is, it is possible to more sum S of the left distance y _L and the right distance y _R is large, avoids torque command value Ia becomes large, encourage more reliably avoided operation.

When the control mode is “one-side support” (the determination in S402 is “Yes”), the default gain Kd is set as the feedback gain K (S403). On the other hand, when the control mode is “both sides support” (determination in S402 is “No”), the feedback gain is obtained by the above (4) having the addition term of the vehicle left and right total margin (y _L + y _R ) in the denominator. K is calculated (S405). Thus, even the road width is narrowed, the distance y ₁ from lane boundary to be avoidance is equal substantially constant, it is possible to maintain the avoidance torque command value Ia substantially constant. That is, as the road width becomes narrower, that is, as the total margin (y _L + y _R ) on the left and right sides of the vehicle becomes smaller, the feedback gain K increases. Therefore, the avoidance torque command value Ia becomes smaller due to the relative decrease of the feedback deviation e. It can be prevented from becoming too much.

Next, the assist torque command value Is is calculated by multiplication of the correction coefficient k (S506).
Here, the steering angle θ when the narrow road support flag changes from “f = 0” to “f = 1” is set as the intervention start steering angle θs (S502, S503). The correction coefficient k is calculated according to the difference Δθ between the angle θ and the intervention start steering angle θs (S505). As a result, the correction coefficient k decreases in the range of 1 to 0 as the driver further steers to the avoidance target side after the narrow road support control is started, so the assist torque command value Is is corrected to decrease. Is done.

  For example, when the control intervention is started when the left road boundary 30 is an object to be avoided and the steering angle θ is −5 ° which is the left turning direction, the steering angle θ is −5 ° thereafter. When the difference is less than 0, the difference Δθ becomes an area less than 0, so that the correction coefficient k decreases in the range of 1 to 0. Since the assist torque command value Is is multiplied by the correction coefficient k, the assist torque command value Is in the left turn direction is corrected to decrease, the steering operation in the left turn direction becomes heavy, and the approach to the left road boundary 30 is reduced. It is suppressed. On the other hand, when the steering angle θ after the control intervention becomes −5 ° or more, the difference Δθ becomes a region of 0 or more, so the correction coefficient k is maintained at 1. Therefore, the correction of the assist torque command value Is is stopped.

As described above, the reduction correction amount for the assist torque command value Is is increased as the steering angle θ after the start of the control intervention increases to the side of the lane boundary to be avoided from the intervention start steering angle θs. Thus, the avoidance operation can be urged more reliably.
Further, the higher the vehicle speed V, the higher the reduction rate of the correction coefficient k with respect to the reduction of the difference Δθ. That is, the higher the vehicle speed V is, the faster the approach speed to the road boundary is, so the reduction correction amount for the assist torque command value Is is increased. Thereby, the avoidance operation can be urged more reliably.

Further, the higher the decrease rate of the distance y _{1 from} the road boundary to be avoided, the higher the decrease rate of the correction coefficient k with respect to the decrease of the difference Δθ. That is, the higher the rate of decrease of the distance y ₁ per unit time, the faster the approaching speed to the road boundary, so the reduction correction amount for the assist torque command value Is is increased. Thereby, the avoidance operation can be urged more reliably.

Further, the shorter the distance y _{1 from the} road boundary to be avoided, the higher the reduction rate of the correction coefficient k with respect to the reduction of the difference Δθ. That is, as the distance y ₁ is shorter, the decrease correction amount with respect to the assist torque command value Is is increased. Thereby, the avoidance operation can be urged more reliably.

  If the driver's steering torque T acts on the side away from the road boundary to be avoided (determination in S504 is “No”), the value of the correction coefficient k is set to 1 (S507). Therefore, if the driver performs a steering operation so as to move away from the avoidance target, the reduction correction of the assist torque command value Is is stopped. That is, when leaving the road boundary to be avoided, the assist torque command value Is returns to the same assist torque as the driver's steering direction, as in the case of a normal electric power steering device. Can be reduced, and a smooth avoidance operation can be realized.

《Application example》
In addition, although the case where side objects, such as a wall, a guardrail, and a fence, were detected as a runway boundary was demonstrated, it is not limited to this, The traffic division line marked on the road surface, or a side ditch etc. is detected. However, the distance to these runway boundaries may be detected.

"effect"
As described above, the electric motor 13 and the assist torque command value calculation unit 20 correspond to the “applying unit”, the sonar sensors 11L and 11R correspond to the “distance detection unit”, the control intervention determination unit 19 and the narrow road support control intervention unit 21. Corresponds to “control intervention means”. Further, the process of calculating the reduction rate of the distance y ₁ to the road boundary to be avoided in step S505 corresponds to “decrease rate calculation means”, the vehicle speed sensor 18 corresponds to “vehicle speed detection means”, and the steering angle sensor Reference numeral 17 corresponds to “steering angle detection means”.

(1) Applying means capable of applying support torque to the driver's steering operation, distance detection means for detecting the distance from the vehicle to the left and right road boundary, and the left and right road boundary detected by the distance detection means Control intervention that prompts the driver to perform an avoidance operation from the boundary of the road to be avoided by determining that the vehicle is running on a narrow road according to the distance to the assist torque of the applying means. Means.
In this way, when the vehicle travels on a narrow road by detecting the distance from the own vehicle to the road boundary, performing control intervention on the support torque according to the detected distance to the road boundary, and performing steering assistance The driver can be intuitively prompted to perform an appropriate steering operation.

(2) The control intervention means increases the control intervention amount with respect to the support torque in the avoidance direction of the road boundary to be avoided as the distance to the road boundary to be avoided is shorter.
Thus, the shorter the distance to the road boundary, the greater the control intervention amount in the direction of avoiding the road boundary, thereby prompting the avoidance operation more reliably.

(3) The control intervention means has a reduction rate calculation means for calculating a reduction rate of the distance to the road boundary to be avoided, and the higher the reduction rate calculated by the reduction rate calculation means, the higher the support torque Is increased in the avoidance direction of the road boundary to be avoided.
As described above, the higher the rate of decrease in the distance to the road boundary, the greater the control intervention amount in the direction of avoiding the road boundary, thereby prompting the avoidance operation more reliably.

(4) The control intervention means includes vehicle speed detection means for detecting the own vehicle speed, and the higher the own vehicle speed detected by the vehicle speed detection means, the more the control intervention amount with respect to the assist torque is determined as the avoidance target road boundary. Increase the direction of avoidance.
As described above, the higher the vehicle speed is, the more the control intervention amount is increased in the direction of avoiding the road boundary, thereby prompting the avoidance operation more reliably.

(5) The control intervention means includes a steering angle detection means for detecting a steering angle, and the assist torque is increased as the steering angle detected by the steering angle detection means is closer to the road boundary to be avoided. Is increased in the avoidance direction of the road boundary to be avoided.
As described above, by increasing the control intervention amount in the direction of avoiding the road boundary as the steering angle is closer to the road boundary, the avoidance operation can be urged more reliably.

(6) The control intervention means, as the sum of the distance to the left lane boundary and the distance to the right lane boundary is longer, the control intervention amount with respect to the assist torque is set to the lane boundary to be avoided. Increase in avoidance direction.
In this way, the longer the sum of the distances to the left and right road boundary, the greater the control intervention amount in the direction of avoiding the road boundary, thereby prompting the avoidance operation more reliably.

(7) The applying unit calculates an assisting torque in a direction to assist a driver's steering operation, and applies the calculated assisting torque as the assisting torque. The control intervention unit is configured to calculate the assisting unit The assist torque is corrected to decrease, the avoidance torque in a direction away from the road boundary to be avoided is calculated, and a value obtained by adding the decrease corrected correction assist torque and the calculated avoidance torque is defined as the final assist torque. To do.
As described above, the value obtained by adding the assist torque that has been corrected for decrease and the calculated avoidance torque is used as the final assist torque, so that the avoidance operation can be urged more reliably.

(8) The control intervention means increases the control intervention amount by increasing the reduction correction amount of the assist torque.
As described above, when the assist torque is decreased and the correction amount is increased, the control intervention amount is increased, and the avoidance operation can be urged more reliably.

(9) The control intervention means increases the control intervention amount by increasing the avoidance torque.
As described above, when the avoidance torque is increased, the control intervention amount is increased, and the avoidance operation can be urged more reliably.

(10) The control intervention means limits the amount of control intervention when the driver's steering torque is acting in the avoidance direction of the road boundary to be avoided.
As described above, when the driver performs the steering operation in the avoidance direction of the road boundary, it is possible to suppress the avoidance operation from being inhibited by limiting the control intervention amount.

(11) The control intervention means uses the steering angle at the time when control intervention is started for the assist torque as an intervention start steering angle, and the steering angle after the start of control intervention is avoided from the intervention start steering angle. The control intervention amount with respect to the assist torque is increased in the avoidance direction of the runway boundary to be avoided as the target road boundary becomes larger.
In this way, as the steering angle after the start of the control intervention becomes larger on the track boundary side than the intervention start steering angle, the control intervention amount is increased in the avoidance direction of the track boundary, thereby avoiding more reliably. The operation can be prompted.

(12) The control intervention means controls the assist torque when the sum of the distance to the left road boundary and the distance to the right road boundary is shorter than a predetermined first threshold. Start intervention.
As described above, when the sum of the distances to the left and right road boundary is shorter than the first threshold, the control intervention can be started at an appropriate timing by starting the control intervention.

(13) The control intervention means starts the control intervention for the assist torque when the distance to either the left or right road boundary is shorter than a predetermined second threshold.
As described above, when the distance to the left or right road boundary is shorter than the second threshold, the control intervention can be started at an appropriate timing by starting the control intervention.

(14) Support torque can be applied to the driver's steering operation, the distance from the vehicle to the left and right road boundary is detected, and it is determined that the vehicle is traveling on a narrow road according to the detected distance to the road boundary. On the other hand, by performing control intervention on the assist torque, the driver is prompted to perform an avoidance operation from the road boundary to be avoided.
In this way, when the vehicle travels on a narrow road by detecting the distance from the own vehicle to the road boundary, performing control intervention on the support torque according to the detected distance to the road boundary, and performing steering assistance The driver can be intuitively prompted to perform an appropriate steering operation.

DESCRIPTION OF SYMBOLS 10 Own vehicle 11L Sonar sensor 11R Sonar sensor 12 Controller 13 Electric motor 14 Torque sensor 15 Steering shaft 16 Steering wheel 17 Steering angle sensor 18 Vehicle speed sensor 19 Control intervention judgment part 20 Assistance torque command value calculation part 21 Narrow path assistance control intervention part 22 Feedback deviation Calculation unit 23 Avoidance torque command value calculation unit 24 Rate limiter 25 Support torque command value correction unit 26 Adder 30 Runway boundary 31 Runway boundary

Claims (14)

An imparting means capable of imparting assist torque to the driver's steering operation;
Distance detection means for detecting the distance from the own vehicle to the left and right runway boundaries;
According to the distance to the left and right road boundary detected by the distance detection means, the road boundary to be avoided is determined by performing control intervention on the support torque of the applying means while determining that the road is narrow. And a control intervention means for prompting the driver to perform an avoidance operation from the vehicle.   The control intervention means increases the control intervention amount with respect to the assist torque in an avoidance direction of the road boundary to be avoided as the distance to the road boundary to be avoided is shorter. The narrow road driving support device according to 1.   The control intervention means has a reduction rate calculation means for calculating a reduction rate of the distance to the lane boundary to be avoided, and the control intervention for the assist torque increases as the reduction rate calculated by the reduction rate calculation means increases. 3. The narrow road driving support device according to claim 1, wherein the amount is increased in an avoidance direction of the road boundary to be avoided.   The control intervention means includes vehicle speed detection means for detecting the own vehicle speed, and the higher the own vehicle speed detected by the vehicle speed detection means, the more the control intervention amount with respect to the assist torque, the avoidance direction of the road boundary to be avoided The narrow road driving support device according to any one of claims 1 to 3, wherein the driving device is made large.   The control intervention means has a steering angle detection means for detecting a steering angle, and the control intervention for the assist torque becomes closer to the side where the steering angle detected by the steering angle detection means is closer to the road boundary to be avoided. 5. The narrow road travel support device according to claim 1, wherein the amount is increased in an avoidance direction of the travel road boundary to be avoided.   The control intervention means increases the control intervention amount with respect to the assist torque in the avoidance direction of the road boundary to be avoided as the sum of the distance to the left road boundary and the distance to the right road boundary is longer. The narrow road driving support device according to any one of claims 1 to 5, wherein the device is made larger. The applying means calculates an assist torque in a direction to assist a driver's steering operation, and applies the calculated assist torque as the assist torque;
The control intervention means corrects the assist torque calculated by the imparting means to decrease, calculates an avoidance torque in a direction away from the lane boundary to be avoided, and calculates the avoidance torque calculated as the assist torque corrected to decrease. The value obtained by adding to the final value is the final assist torque. The narrow road travel assist device according to any one of claims 1 to 6.   8. The narrow road running support apparatus according to claim 7, wherein the control intervention means increases the control intervention amount by increasing a reduction correction amount of the assist torque.   9. The narrow road running support apparatus according to claim 7 or 8, wherein the control intervention means increases the control intervention amount by increasing the avoidance torque.   The control intervention means limits the control intervention amount when the driver's steering torque is acting in the avoidance direction of the road boundary to be avoided. The narrow road driving support device according to one item.   The control intervention means uses the steering angle at the time of starting control intervention for the assist torque as an intervention start steering angle, and the steering angle after the start of control intervention is a target to be avoided rather than the intervention start steering angle. 11. The control intervention amount with respect to the assist torque is increased in an avoidance direction of the travel path boundary to be avoided as the distance increases toward the travel path boundary. 11. Narrow road driving support device.   The control intervention means starts control intervention for the assist torque when the sum of the distance to the left road boundary and the distance to the right road boundary is shorter than a predetermined first threshold value. The narrow road driving support device according to any one of claims 1 to 11, wherein:   The control intervention means starts the control intervention for the assist torque when a distance to either the left or right lane boundary is shorter than a predetermined second threshold value. The narrow road driving assistance device according to 1 to 12.   Assistance torque can be applied to the driver's steering operation, the distance from the own vehicle to the left and right road boundary is detected, and according to the detected distance to the road boundary, it is determined that the vehicle is traveling on a narrow road, A narrow road driving support method, characterized by prompting the driver to perform an avoidance operation from the road boundary to be avoided by performing control intervention on the support torque.

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