JP2001138941A - Automatic steering system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit precise automatic parking by preventing the discrepancy of a moving locus while minimizing time required for automatic parking. SOLUTION: This automatic steering system for a vehicle steers front wheels by a steering actuator on the basis of a moving locus previously stored as the relation of a normative steering angle θ ref of a steering wheel to the moving distance X of the vehicle. In this constitution, when the inclination of a moving locus line is made Δθref/ΔX, and the maximum steering angle speed determined by the performance of the steering actuator is made αmax, the limit vehicle speed Vlim during automatic steering control is set by Vlim (ΔX/Δθref).αmax. This can prevent the discrepancy of the moving locus generated by the actuation delay of the steering actuator 7 caused by the overspeed of the vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic vehicle steering system for automatically parking a vehicle without relying on a driver's steering operation.

[0002]

2. Description of the Related Art Such an automatic steering apparatus for a vehicle is disclosed in Japanese Unexamined Patent Publication No.
It is already known from 193691. This automatic steering apparatus for a vehicle utilizes a steering actuator of a conventionally known electric power steering apparatus, and controls the steering actuator based on a relationship between a moving distance of the vehicle and a steering angle stored in advance, so that the back parking is performed. And parallel parking is performed automatically.

[0003]

However, since the reference steering angle during the automatic steering control is set as a function of the moving distance of the vehicle, when the moving speed of the vehicle during the automatic steering control increases, the wheels rotate. The operating speed required for the steering actuator to be steered also increases. Therefore, when the vehicle travels at an excessive speed, the performance of the steering actuator may be insufficient and the actual steering angle may not be able to follow the reference steering angle, and the vehicle may deviate from the target travel locus. There is.

If the vehicle speed limit during the automatic steering control is set to a low limit in order to solve such a problem, if the steering actuator has a margin of performance or the steering angle is constant, the steering actuator cannot be used. Even when the vehicle is stopped, the vehicle speed is limited to a low value, and there is a problem that the time required for parking is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to prevent a shift of a moving trajectory while minimizing the time required for automatic parking, thereby enabling precise automatic parking. .

[0006]

In order to achieve the above object, according to the first aspect of the present invention, a trajectory setting means for storing or calculating a trajectory of a vehicle to a target position and a wheel are provided. A steering actuator that steers,
An actuator control means for controlling driving of the steering actuator based on a movement locus set by the movement locus setting means while the vehicle moves to the target position. Vehicle speed setting means for setting a vehicle speed limit during control, wherein the vehicle speed setting means sets the vehicle speed limit so that a turning angular speed for the vehicle to move on the movement locus is equal to or less than a predetermined value. An automatic steering device for a vehicle is proposed.

[0007] According to the above configuration, the vehicle speed setting means sets the limit vehicle speed such that the turning angular velocity for the vehicle to move on the movement locus is equal to or less than the predetermined value during the control of the steering actuator by the actuator control means. So
Since the vehicle speed is excessive, it is possible to prevent the vehicle from deviating from the target movement trajectory due to insufficient steering angular velocity by the steering actuator.

According to the invention described in claim 2,
In addition to the configuration of the first aspect, there is proposed an automatic steering apparatus for a vehicle, wherein the movement trajectory setting means sets the movement trajectory of the vehicle as a relation of the turning angle to the movement distance of the vehicle.

[0009] According to the above configuration, the moving locus of the vehicle is set as the relation of the steering angle to the moving distance of the vehicle.
Even if the vehicle speed slightly changes during the automatic steering control, it is possible to prevent the movement locus from shifting.

According to the third aspect of the present invention,
In addition to the configuration of claim 1 or 2, the automatic steering device for a vehicle is proposed, wherein the predetermined value is set based on a maximum turning angular velocity that can be output by a steering actuator.

According to the above configuration, the vehicle speed is limited to a predetermined value or less based on the maximum turning angular velocity that can be output by the steering actuator. Therefore, the vehicle deviates from the target locus due to insufficient performance of the steering actuator. Can be reliably prevented.

According to the invention described in claim 4,
In addition to the configuration according to any one of claims 1 to 3, the vehicle speed setting unit includes an alarm unit that sets an alarm vehicle speed lower than the limit vehicle speed and issues an alarm to a driver when the vehicle speed exceeds the alarm vehicle speed. An automatic steering device for a vehicle is proposed.

According to the above configuration, a warning is issued to the driver when the vehicle speed exceeds the warning vehicle speed lower than the vehicle speed limit. Therefore, the vehicle speed is prevented from exceeding the vehicle speed limit by the driver's voluntary deceleration operation. be able to.

According to the fifth aspect of the present invention,
An automatic steering device for a vehicle is proposed, which further comprises an automatic deceleration means for limiting the vehicle speed to the vehicle speed equal to or lower than the limited vehicle speed in addition to any one of the above-described structures.

According to the above configuration, since the automatic deceleration means limits the vehicle speed to the speed lower than the speed limit, it is possible to surely prevent the vehicle speed from exceeding the speed limit even when the driver does not perform a spontaneous deceleration operation. The operation burden of the driver can be reduced.

Further, according to the invention described in claim 6,
In addition to the configuration according to any one of the first to fifth aspects, there is proposed an automatic steering apparatus for a vehicle, wherein the vehicle speed setting means increases the limited vehicle speed during steering by the steering actuator.

According to the above configuration, the vehicle speed limit is increased during steering by the steering actuator, so that it is possible to prevent the vehicle speed from being limited without limitation and increasing the time required for garage entry.

The control unit 22 of the embodiment corresponds to the actuator control unit of the present invention, the storage unit 23 of the embodiment corresponds to the moving trajectory setting unit of the present invention, and the front wheel Wr of the embodiment corresponds to the wheel of the present invention. Corresponding to

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 5 show an embodiment of the present invention. FIG. 1 is an overall structural view of a vehicle provided with an automatic steering device, FIG. FIG. 4 is a diagram showing a mode selection switch and an automatic parking start switch, FIG. 4 is a block diagram of a vehicle speed control device, and FIG. 5 is a diagram for explaining setting of a limit vehicle speed and a warning vehicle speed.

As shown in FIG. 1, the vehicle has a pair of front wheels W
f, Wf and a pair of rear wheels Wr, Wr. The steering wheel 1 and the front wheels Wf, Wf, which are the steered wheels,
A steering shaft 2 that rotates integrally with the steering wheel 1; a pinion 3 provided at the lower end of the steering shaft 2; , 5 are connected by left and right knuckles 6, 6. A steering actuator 7 composed of an electric motor is connected to the steering shaft 2 via a worm gear mechanism 8 in order to assist the driver in operating the steering wheel 1 or to perform automatic steering for garage described later.

The steering control device 21 includes a control unit 22 and a storage unit 2
The control unit 22 includes a steering angle detection unit Sa that detects a steering angle θ that is a rotation angle of the steering wheel 1, and a steering torque detection unit that detects a steering torque T of the steering wheel 1. Means Sb, left and right front wheels W
front wheel rotation angle detecting means Sc for detecting the rotation angles f and Wf.
Sc, a brake operation amount detecting means Sd for detecting an operation amount of the brake pedal 9, and a shift range (“D” range, “R” range,
A signal is input from the shift range detecting means Se for detecting the “N” range, the “P” range, and the like.

Referring to FIG. 3 together, it is apparent that
The mode selection switch Sf and the automatic parking start switch Sg operated by the driver are connected to the control unit 22. The mode selection switch Sf has four types of parking modes to be described later: a back parking / right mode, a back parking /
It has four buttons operated when selecting any of the left mode, the parallel parking / right mode, and the parallel parking / left mode. The automatic parking start switch Sg is operated when starting automatic parking in one of the modes selected by the mode selection switch Sf.

The storage unit 23 stores data of the four types of parking modes, that is, the standard steering angle θ with respect to the moving distance X of the vehicle.
The relationship of ref is stored in advance as a table.
The moving distance X of the vehicle is obtained by multiplying the known circumference of the front wheel Wf by the rotation angle of the front wheel Wf detected by the front wheel rotation angle detection means Sc, Sc. The moving distance X
Is calculated by a pair of left and right front wheel rotation angle detection means Sc, Sc
, The high select value, the low select value, or the average value of the output is used.

The control unit 22 includes the detecting means Sa to Se.
Based on the signals from the switches Sf and Sg and the parking mode data stored in the storage unit 23, the operation of the steering actuator 7 and the teaching of operation steps including a liquid crystal monitor, a speaker, a lamp, a chime, a buzzer, etc. The operation of the device 11 is controlled. Also brake pedal 9
Is connected to an electronically controlled negative pressure booster 12,
The negative pressure booster 12 automatically operates based on a command from the control unit 22 to generate a braking force, in addition to operating based on the driver's treading force.

FIG. 4 shows the vehicle speed V during the automatic steering control.
A vehicle speed control device provided in the control unit 22 to limit the vehicle speed is shown. The vehicle speed control device provided in the control unit 22 calculates the distance change amount ΔX and the turning angle change amount Δθ of the moving trajectory stored in advance in the storage unit 23 and the maximum turning angular speed αmax that can be output by the steering actuator 7. On the basis of,
The vehicle speed setting means M1 for setting the limit vehicle speed Vlim and the warning vehicle speed Vala, and the negative pressure booster 12 is operated so that the vehicle speed V during the automatic steering control does not exceed the limit vehicle speed Vlim set by the vehicle speed setting means M1. Automatically decelerating means M2 for automatically lowering the vehicle, and alarm means for prompting the driver to decelerate with light or sound by operating the operation stage teaching means 11 when the vehicle speed V during automatic steering reaches the alarm vehicle speed Vala set by the vehicle speed setting means M1. M3. The vehicle speed V of the vehicle can be calculated by differentiating the output of the front wheel rotation angle detection means Sc, Sc.

Next, a method of setting the limit vehicle speed Vlim and the warning vehicle speed Vala by the vehicle speed setting means M1 will be described.

The maximum value of the turning angular velocity α, which is the time rate of change of the turning angle θ by the steering actuator 7, that is, the maximum turning angular velocity αmax is determined by the battery voltage and the output characteristics of the steering actuator 7.

As shown in FIG. 5, the line of the movement trajectory stored in advance has two regions R1 and R3 having a constant inclination ± Δθref1 / ΔX1, and a constant inclination ± Δθref2.
/ ΔX2, and four regions R2, R4, R6, and R8 having a slope of 0.

In order for the vehicle to correctly move on the movement locus stored in advance, the reference steering angular velocity α during the automatic steering control is set.
ref needs to satisfy αref ≦ αmax (1). Because αref> αmax
In this case, the actual turning angle θ cannot follow the reference turning angle θref, and the vehicle deviates from the movement trajectory stored in advance.

If Δt is a minute time, the reference turning angle velocity αref obtained by differentiating the reference turning angle θref with respect to time is as follows: αref = Δθref / Δt = (Δθref / ΔX) · (ΔX / Δt) = (Δθref / ΔX) ) · V (2) That is, the reference turning angular velocity αref is represented by the product of the inclination Δθref / ΔX of the line of the movement locus and the vehicle speed V.

By substituting equation (2) into equation (1), the following is obtained: V ≦ (ΔX / Δθref) · αmax (3) Equation (3) indicates that if the vehicle speed V during the automatic steering control is suppressed to (Δθref / ΔX) · αmax or less, the vehicle can correctly move on the movement trajectory stored in advance without causing a steering delay. ing. Therefore, in this embodiment, the limit vehicle speed Vlim during the automatic steering control is set by Vlim ≦ (ΔX / Δθref) · αmax (4), and the automatic deceleration means M2 is operated so as not to exceed the limit vehicle speed Vlim. It has become.

As shown in FIG. 5, the regions R1 and R
In 3, the inclination of the line of the movement locus is ± Δθref1 / ΔX
1, the vehicle speed limit Vli in the regions R1 and R2.
m1 is represented by (ΔX1 / Δθref1) · αmax. In the regions R5 and R7, since the inclination of the line of the movement locus is ± Δθref2 / ΔX2, the vehicle speed limit Vlim2 in the regions R5 and R7 is (ΔX2 / Δθ
ref2) · αmax.

A region R where the inclination of the line of the moving trajectory is large
In R5 and R7, the amount of increase of the reference turning angle θref with respect to the amount of increase of the movement trajectory X is large, and if the vehicle speed V is large, the operation of the steering actuator 7 cannot be performed in time.
The vehicle speed limit Vlim2 in the regions R5 and R7 is small. On the other hand, a region R in which the inclination of the line of the movement locus is small
At 1 and R3, the amount of increase of the reference turning angle θref with respect to the amount of increase of the movement trajectory X is small, and the operation of the steering actuator 7 can be in time even if the vehicle speed V is large. Has become.

The region R in which the steering actuator 7 stops and the reference turning angle θref is maintained at a constant value.
2, R4, R6, and R8, there is no displacement of the movement trajectory due to the operation delay of the steering actuator 7, and the vehicle speed limit Vlim0 is limited to the region R1,
Vehicle speed limits Vlim1, Vlim2 at R3, R5, R7
It is set to a constant value which is larger than the above, thereby shortening the time required for garage storage. The region R
The limit vehicle speed Vlim0 at 1, R3, R5, and R7 is set, for example, as a vehicle speed V at which the driver can stop immediately upon finding an obstacle.

As shown by the thick broken line in FIG. 5, the vehicle speed V obtained by reducing the limit vehicle speeds Vlim0, Vlim1 and Vlim2 at a predetermined ratio (for example, 80%) is used to prompt the driver to voluntarily decelerate. This is set as the alarm vehicle speed Vala.

Next, the operation of the embodiment of the present invention having the above-described configuration will be described.

In normal times when the automatic parking is not performed (when the mode selection switch Sf is not operated), the steering control device 21 functions as a general power steering control device. Specifically, when the driver operates the steering wheel 1 to turn the vehicle, the steering torque detecting means Sb detects the steering torque T input to the steering wheel 1, and the control unit 22 sends the steering torque T
, The driving of the steering actuator 7 is controlled. As a result, the left and right front wheels Wf, Wf are steered by the driving force of the steering actuator 7, and the steering operation of the driver is assisted.

Next, the contents of the automatic steering control will be described with reference to a back parking / left mode (a mode in which the vehicle is parked while backing to a parking position on the left side of the vehicle).

First, as shown in FIG. 2 (A), the driver moves the vehicle to the vicinity of the garage to be parked by the steering operation of the driver himself, and sets the left side of the vehicle body as close as possible to the garage entrance line. The vehicle is stopped at a position (start position) where a determined reference (for example, a mark or a side mirror provided inside the door) matches the center line of the garage. Then, by operating the mode selection switch Sf to select the back parking / left mode and turning on the automatic parking start switch Sg, the automatic steering control is started. While the automatic steering control is being performed, the operation stage teaching device 11 switches the current position of the own vehicle, surrounding obstacles, the parking position, the expected movement trajectory of the own vehicle from the start position to the target position, and forward to reverse. The turning position and the like are displayed, and various instructions and warnings such as operation of the select lever 10 at the turning position are given to the driver by voice from the speaker.

By the automatic steering control, even if the driver only releases the brake pedal 9 to cause the vehicle to creep and operate the steering wheel 1 without operating the steering wheel 1, the data is based on the data of the back parking / left mode selected by the mode selection switch Sf. Thus, the front wheels Wf, Wf are automatically steered. That is, the front wheels Wf, Wf are automatically steered to the right while the vehicle moves forward from the start position to the turning position, and the front wheels Wf are driven while the vehicle moves backward from the turning position to the target position.
f and Wf are automatically steered to the left.

As is clear from FIG. 2B, while the automatic steering is being performed, the control unit 22 reads the reference parking angle θref of the back parking / left mode read from the storage unit 23 and detects the steering angle. A deviation E (= θref−θ) is calculated based on the steering angle θ input from the means Sa, and the operation of the steering actuator 7 is controlled so that the deviation E becomes zero. At this time, since the data of the reference steering angle θref is set in accordance with the moving distance X of the vehicle, the vehicle always moves on the moving locus even if the vehicle speed of the creep running varies slightly. Become.

Since the above-mentioned automatic steering control is executed while the driver depresses the brake pedal 9 and the vehicle creeps, the driver must immediately depress the brake pedal 9 to stop the vehicle when an obstacle is found. Can be.

The above-described automatic steering control is stopped when the driver turns off the mode selection switch Sf. In addition, when the driver releases the brake pedal 9, the driver operates the steering wheel 1. In this case, the operation is stopped and the control returns to the normal power steering control.

The vehicle speed V during the automatic steering control is changed by the driver's brake operation or accelerator operation, and the vehicle speed V is limited to the vehicle speed limits Vlim0 and Vl shown in FIG.
When an alarm vehicle speed Vala lower than im1 and Vlim2 is reached, the alarm means M3 activates the operation stage display device 11 to urge the driver to decelerate with light or sound, so that the vehicle speed V approaches the limit vehicle speed Vlim1 or Vlim2. To prevent As a result, the execution of the automatic braking described later can be avoided as much as possible.

Despite the operation of the operation stage display device 11, the vehicle speed V is limited to the limited vehicle speeds Vlim0 and Vlim shown in FIG.
When the vehicle approaches m1, Vlim2, the negative pressure booster 12 automatically operates according to a command from the automatic deceleration means M2, and performs automatic braking so that the vehicle speed V does not exceed the limit vehicle speeds Vlim0, Vlim1, Vlim2. Thus, it is possible to prevent the operation locus of the steering actuator 7 from being delayed due to the excessive vehicle speed V and to shift the movement trajectory while reducing the operation burden on the driver, thereby enabling highly accurate automatic parking. In addition, the vehicle speed limits Vlim0, Vlim1, V
lim2 can be set as high as possible according to the maximum turning angular velocity αmax and the inclination of the line of the movement locus, and the time required until the end of the automatic steering control can be shortened.

Although the embodiments of the present invention have been described above, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, the trajectory of the vehicle to the target position is stored in the storage unit 23 in advance. However, the trajectory can be calculated from the current position and the target position of the vehicle. In the embodiment, the automatic deceleration means M2 operates the negative pressure booster 12 to perform the automatic deceleration. However, the automatic deceleration may be performed by other means such as a valve closing control of the throttle valve. .

[0049]

As described above, according to the first aspect of the present invention, during the control of the steering actuator by the actuator control means, the turning angular velocity for the vehicle to move on the movement locus becomes equal to or less than the predetermined value. Since the vehicle speed setting means sets the vehicle speed limit so that the vehicle speed is excessive, it is possible to prevent the vehicle from deviating from the target movement trajectory due to insufficient steering angular velocity by the steering actuator due to excessive vehicle speed.

According to the second aspect of the present invention,
Since the trajectory of the vehicle is set as the relationship of the steering angle to the distance traveled by the vehicle, the trajectory can be prevented from shifting even if the vehicle speed slightly changes during the automatic steering control.

According to the third aspect of the present invention,
Since the vehicle speed limit is limited to a predetermined value or less based on the maximum turning angular velocity that can be output by the steering actuator, it is possible to reliably prevent the vehicle from deviating from the target trajectory due to insufficient performance of the steering actuator. .

According to the fourth aspect of the present invention,
Since a warning is issued to the driver when the vehicle speed exceeds the warning vehicle speed lower than the vehicle speed limit, it is possible to prevent the vehicle speed from exceeding the vehicle speed limit by the driver's voluntary deceleration operation.

According to the fifth aspect of the present invention,
Since the automatic deceleration means limits the vehicle speed below the limit vehicle speed, it is possible to reliably prevent the vehicle speed from exceeding the limit vehicle speed even when the driver does not voluntarily decelerate, and reduce the driver's operation burden. You.

According to the invention described in claim 6,
Since the limit vehicle speed increases during steering by the steering actuator, it is possible to prevent the vehicle speed from being limited unnecessarily and increasing the time required for garage entry.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a vehicle including an automatic steering device.

FIG. 2 is an explanatory diagram of an operation in a back parking / left mode.

FIG. 3 is a diagram showing a mode selection switch and an automatic parking start switch.

FIG. 4 is a block diagram of a vehicle speed control device.

FIG. 5 is a diagram illustrating setting of a limit vehicle speed and a warning vehicle speed.

[Explanation of symbols]

 7 Steering actuator 22 Control unit (actuator control unit) 23 Storage unit (movement trajectory setting unit) M1 Vehicle speed setting unit M2 Automatic deceleration unit M3 Warning unit V Vehicle speed Vala Warning vehicle speed Vlim Limit vehicle speed Wf Front wheel (wheel) X Travel distance αmax Maximum rotation Steering angle speed θ Steering angle

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D032 CC20 DA03 DA09 DA15 DA22 DA24 DA91 DA93 DA95 DB07 DC03 DC04 DC34 DC40 EA01 EB04 EB11 EC22 FF01 GG01 3D033 CA03 CA11 CA12 CA13 CA16 CA17 CA21 CA33

Claims (6)

[Claims] 1. A trajectory setting means (23) for storing or calculating a trajectory of a vehicle to a target position; a steering actuator (7) for turning a wheel (Wf); Trajectory setting means (2
And (3) an actuator control means (22) for controlling the driving of the steering actuator (7) based on the movement trajectory set by (3). ) Is provided with a vehicle speed setting means (M1) for setting a vehicle speed limit (Vlim) during the control of the vehicle. An automatic steering apparatus for a vehicle, wherein the vehicle speed limit (Vlim) is set such that 2. The trajectory setting device according to claim 1, wherein the trajectory setting means sets the trajectory of the vehicle as a relation of the steering angle (θ) with respect to the travel distance (X) of the vehicle. Automatic vehicle steering system. 3. The automatic steering of a vehicle according to claim 1, wherein the predetermined value is set based on a maximum turning angular velocity (αmax) that can be output by a steering actuator. apparatus. 4. A vehicle speed setting means (M1) sets a warning vehicle speed (Vala) lower than the limit vehicle speed (Vlim), and issues a warning to a driver when the vehicle speed (V) exceeds the warning vehicle speed (Vala). The automatic steering apparatus for a vehicle according to any one of claims 1 to 3, further comprising an alarm unit (M3) for issuing an alarm. 5. The vehicle speed (V) is changed to the vehicle speed limit (Vlim).
The automatic steering device for a vehicle according to any one of claims 1 to 4, further comprising an automatic deceleration means (M2) for limiting the following. 6. A vehicle speed setting means (M1) for controlling the vehicle speed (V) during steering by a steering actuator (7).
lim) is increased.
An automatic steering device for a vehicle according to any one of the above.