JPH11198840A - Automatic steering device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent certainly a vehicle from moving in a direction out of driver's intention when a steering angle sensing means of an automatic steering device goes in failure. SOLUTION: A steering angle sensing means S1 to sense the actual steering angle of a vehicle wheel for performing the automatic steering control is composed of the first sensor element 13a and a second sensor element 13b. These sensor elements 13a and 13b consist of potentiometer etc., and are connected to a comparing means 14. The comparing means 14 compares the steering angles θa and θb sensed by the first 13a and second sensor elements 13b, respectively, and if the error between the two exceeds a certain value, for example 5 degrees, an automatic steering control interrupting means 16 sends an interrupt command signal to a steering actuator driving means 17.

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 An automatic steering apparatus for such a vehicle is disclosed in Japanese Patent Laid-Open Publication No.
No. 74256 and JP-A-4-55168. The automatic steering devices for these vehicles use an actuator of a conventionally known electric power steering device, and control the actuator based on a relationship between a moving distance of the vehicle and a steering angle stored in advance to control the back parking or the like. Parallel parking is performed automatically.

[0003]

By the way, in the prior art, the drive of the actuator is controlled so that the turning angle of the vehicle coincides with the reference turning angle stored in advance. If the steering angle detecting means for detecting the angle breaks down, the vehicle cannot be moved along the target movement trajectory, and the vehicle may move in an unexpected direction.

[0004] The present invention has been made in view of the above circumstances, and when the steering angle detecting means of the automatic steering device breaks down,
An object is to surely prevent a vehicle from moving in an unexpected direction.

[0005]

In order to achieve the above object, according to the present invention, there is provided a trajectory setting means for storing or calculating a trajectory of a vehicle to a target position;
An actuator for turning the wheel, a turning angle detecting means for detecting a turning angle of the wheel, and a turning angle detected by the turning angle detecting means such that the turning angle coincides with a reference turning angle corresponding to the movement locus. In an automatic steering apparatus for a vehicle including an actuator control unit that controls driving of an actuator, a turning angle detection unit includes a first turning angle detection unit and a second turning angle detection unit, and the actuator control unit includes: The first,
The control of the actuator based on the movement trajectory is stopped when the output of the second steering angle detecting means does not match.

According to the above arrangement, the first steered angle detecting means and the second steered angle detecting means detect the steered angles of the wheels, respectively. Since the control of the actuator based on the movement trajectory is stopped by judging that the steering angle detecting means has failed, the automatic steering control based on the incorrect steering angle is performed and the vehicle moves in an unexpected direction. Can be reliably prevented.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the actuator is an electric motor, and one of the first and second steering angle detecting means includes:
Voltage detection means for detecting a terminal voltage of the actuator,
Current detection means for detecting a current supplied to the actuator;
A rotation angle calculation unit that calculates a rotation angle of the actuator based on the terminal voltage and the energizing current, and a steering angle calculation unit that calculates a steering angle based on the rotation angle of the actuator.

According to the above configuration, the rotation angle is calculated from the terminal voltage and the current supplied to the actuator, and the steering angle of the wheel is calculated from the rotation angle of the actuator. The turning angle can be detected by using the voltage detecting means and the current detecting means, which eliminates the need for providing a special turning angle detecting means, which can contribute to cost reduction.

[0009]

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.

FIG. 1 to FIG. 4 show a first embodiment of the present invention. FIG. 1 is an overall configuration diagram of a vehicle provided with a steering control device.
FIG. 2 is a diagram illustrating the operation of the back parking / left mode, FIG. 3 is a diagram illustrating a mode selection switch and an automatic parking start switch, and FIG. 4 is a block diagram of a control system.

As shown in FIG. 1, a vehicle V 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, a rack 4 meshing with the pinion 3, left and right tie rods 5, 5 provided at both ends of the rack 4, and a tie rod 5 , 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
3 which are composed of, the control unit 22, the front wheels Wf based on a rotation angle of the steering wheel 1, a steering angle detecting means S ₁ for detecting the turning angle θact of Wf, steering torque of the steering wheel 1 detecting a steering torque detecting means S _2, the left and right front wheels Wf, a front wheel rotational angle detecting means S _3, S ₃ for detecting the rotation angle of Wf, brake operation amount detecting means for detecting an operation amount of the brake pedal 9 S ₄ and the shift range (“D”) selected by the select lever 10
Range, "R" range, "N" range, the "P" shift range detecting means S ₅ for detecting a range, etc.), the front of the vehicle V, the central part and a total of eight object detecting means provided in the rear The signal from S ₆ is input. The object detecting means S ₆ comprises a known sonar, radar, television camera or the like. The eight object detecting means S ₆ ... And the control unit 2
2 are omitted to avoid complicating the drawing. The control unit 22 constitutes an actuator control unit of the present invention, and the storage unit 23 constitutes a movement locus setting unit of the present invention.

Referring to FIG. 3 together, it is apparent that
Mode selection switch S ₇ and automatic parking start switch S ₈ is operated by the driver is connected to the control unit 22. Mode selection switch S _7, the four types of parking mode, which will be described later, that is the back parking / right mode, the 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. Automatic parking start switch S ₈ is operated to start automatic parking according to any of the mode selected by the mode selection switch S _7.

In the storage unit 23, data of the four types of parking modes, that is, the relationship of the reference turning angle θref to the moving distance X of the vehicle V is stored in advance as a table.

The control unit 22 includes the detection means S _{1 to} S _6.
Based on the signals from the switches S ₇ and S ₈ and the parking mode data stored in the storage unit 23, the operation of the steering actuator 7 and the operation including the liquid crystal monitor, speaker, lamp, chime, buzzer, etc. The operation of the step teaching device 11 is controlled.

FIG. 4 shows the structure of a part of the control unit 22 which controls the steering actuator 7.

[0017] The first turning angle detecting means 13a for each of the steering angle detecting means S ₁ is constructed from a potentiometer or the like
And second turning angle detecting means 13b,
The turning angle detecting means 13 a and 13 b are connected to the comparing means 14. The comparing means 14 includes the first and second steering angle detecting means 13
The steering angles θa and θb detected in steps a and b are compared, and when the error between the two steering angles θa and θb is less than 5 °, for example, the high select value, low select value, or average value is calculated. It is output to the deviation calculating means 15 as the turning angle θact. On the other hand, when the error between the two turning angles θa and θb is 5 ° or more, the automatic steering control stopping means 16 outputs an automatic steering control stop command signal to the steering actuator driving means 17.

The rotation angles of the front wheels Wf, Wf detected by the front wheel rotation angle detecting means S ₃ , S ₃ are inputted to the moving distance detecting means 18, and the moving distance detecting means 18 knows the front wheels Wf, W.
the front wheels Wf detected by wheel rotation angle detecting means S _3, S ₃ in the circumferential length of f, the moving distance X of the vehicle V is determined by multiplying the rotation angle of Wf. The moving distance X is calculated using a high select value, a low select value, or an average value of the outputs of the pair of left and right front wheel rotation angle detecting means S ₃ , S ₃ .

The reference turning angle θref (see FIG. 2B) read from the storage unit 23 based on the moving distance X of the vehicle V detected by the moving distance detecting means 18 is calculated by the deviation calculating means 1.
5, the deviation calculating means 15 outputs the reference steering angle θref.
E (= θref−θac) between the actual steering angle θact and
t), and calculates the steering actuator driving means 1
7 controls the operation of the steering actuator 7 so that the deviation E becomes zero. At this time, the reference steering angle θr
Since the data of ef is set in accordance with the moving distance X of the vehicle V, the vehicle V always moves on the movement locus even if there is some fluctuation in the vehicle speed of the creep running.

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

[0021] During normal not used to automatically parking (when the mode selecting switch S ₇ is not operated), the steering control apparatus 21 functions as a general power steering control unit. Specifically, when the driver operates the steering wheel 1 to turn the vehicle V, a steering torque detecting means S ₂ detects the steering torque inputted to the steering wheel 1, the control unit 22 based on the steering torque 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 by taking a back parking / left mode (a mode in which the vehicle is parked while backing at a parking position on the left side of the vehicle V) as an example.

First, as shown in FIG. 2 (A), the vehicle V is moved to the vicinity of the garage to be parked by the driver's own steering operation, and the left side surface of the vehicle body is brought as close as possible to the garage entrance line. Predetermined criteria (for example, marks or side mirrors inside doors)
Stops the vehicle V at a position (start position) that coincides with the center line of the garage. Then, ON the automatic parking start switch S ₈ with to select the back parking / left mode by operating the mode selection switch S ₇ Then, 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.

[0024] by the automatic steering control, driver of alone without operating the steering wheel 1, which is selected by the mode selection switch S ₇ back parking / left mode to creep running the vehicle V loosen the brake pedal 9 data , The front wheels Wf, Wf are automatically steered. That is, the front wheels Wf, Wf are automatically steered to the right while the vehicle V moves forward from the start position to the turning position, and the front wheels Wf, Wf are automatically steered to the left while the vehicle V moves backward from the turning position to the target position. .

As is clear from FIG. 2B, while the automatic steering is being performed, the control unit 22 reads the reference steering angle θref of the back parking / left mode read from the storage unit 23 and the first and second reference angles. The deviation E (= θref−) based on the actual turning angle θact obtained from the outputs of the two turning angle detecting means 13a and 13b.
θact) is calculated, and the operation of the steering actuator 7 is controlled such that the deviation E becomes zero.

Since the above-mentioned automatic steering control is executed while the driver depresses the brake pedal 9 and the vehicle is creeping, when the driver finds an obstacle, the driver depresses the brake pedal 9 immediately to stop the vehicle V. Can be stopped.

The automatic steering control described above, the driver but is released when OFF the mode selecting switch S _7, if the driver also has otherwise takes his foot from the brake pedal 9, the driver operates the steering wheel 1 If any one of the object detection means S ₆ detects an obstacle, the first and second steering angle detection means 13 a and 13 b
Are released when the outputs of the control signals do not match, and return to the normal power steering control.

Next, the first and second steering angle detecting means 13a,
The suspension of the automatic steering control in the case where the output of 13b does not match will be further described.

In FIG. 4, the first steering angle detecting means 13a
Steering angle θa and second steering angle detecting means 13b
The comparing means 14 to which the steering angle θb detected in step (1) is inputted compares the two steering angles θa and θb, and when the error between them is 5 ° or more, the first and second steering angle detecting means 13a and 13b Is determined to have failed. In such a case, if a high select value, a low select value, or an average value of both the turning angles θa and θb is used as the actual turning angle θact, the automatic steering control can be accurately performed by the error of the actual turning angle θact. May not be performed, and the trajectory of the vehicle V may deviate from the reference trajectory.

Therefore, in such a case, the automatic steering control stopping means 16 is provided by the steering actuator driving means 1.
By stopping the automatic steering control by outputting the automatic steering control stop command signal to 7, the vehicle V can be prevented from moving in an unexpected direction. At this time, the operation stage teaching device 11 notifies the driver that the automatic steering control has been stopped by voice from a speaker.

The first and second steering angle detecting means 13a, 1
3b, not only when the turning angles θa and θb output from each other do not coincide with each other, but also when their change rates dθa / dt and dθb /
The automatic steering control is also stopped when the dt error becomes, for example, 1 rad / sec or more, or when one of the two turning angles θa and θb changes but the other does not change (a constant value). Can be.

Next, a second embodiment of the present invention will be described with reference to FIGS.

The second embodiment does not include the second steering angle detecting means 13b (see FIG. 4) of the first embodiment. Instead, it is based on the rotation angle α of the steering actuator 7 composed of an electric motor. The steering angle θb is detected. The second turning angle detecting means 13b includes a voltage detecting means 31 for detecting a terminal voltage u of the steering actuator 7.
A current detection means 32 for detecting a current i flowing through the steering actuator 7, a terminal voltage u and a current i
Rotation angle calculating means 33 for calculating the rotation angle α of the steering actuator 7 based on the rotation angle α, and the front wheels Wf, Wf steering angle θ based on the rotation angle α of the steering actuator 7.
and a turning angle calculating means 34 for calculating b (see FIG. 5).

In the model of the electric motor 7 shown in FIG. 6, if the terminal voltage is u, the energizing current is i, the resistance is R, the inductance is L, the back electromotive force is e, and the rotation angle is α, the terminal voltage u becomes

[0035]

(Equation 1)

[0036]

(Equation 2)

Is represented by Here, K is a constant determined by the characteristics of the steering actuator 7.

From the above equations (1) and (2), the rotation angle α
Is

[0039]

(Equation 3)

Is calculated by In the equation (3), the inductance L is generally small and can be omitted. As a result, the equation (3) is as follows.

[0041]

(Equation 4)

As is apparent from the equation (4), the constants R, K
Is determined, the rotation angle α of the steering actuator 7 can be calculated based on the terminal voltage u and the conduction current i. Since the rotation angle α of the steering actuator 7 and the turning angle θb of the front wheels Wf, Wf have a fixed relationship, the turning angle θb of the front wheels Wf, Wf is calculated based on the rotation angle α of the steering actuator 7. Voltage detecting means 31 and current detecting means 32
Is standard on electric power steering systems, so no special costs are required to equip it.

Thus, similarly to the first embodiment, the turning angle θa detected by the first turning angle detecting means 13a composed of a potentiometer and the turning angle detected by the second turning angle detecting means 13b of the present embodiment. If the error from the steering angle θb is 5 ° or more, it is determined that one of the first and second steering angle detecting means 13a and 13b has failed, and the automatic steering control stopping means 16 An automatic steering control stop command signal is output to stop the automatic steering control. Note that the two turning angles θa, θ output by the first and second turning angle detecting means 13a, 13b are provided.
When the error of the rate of change dθa / dt, dθb / dt of b becomes, for example, 1 rad / sec or more, or when one of the two turning angles θa, θb changes but the other does not change, The steering control can be stopped.

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 vehicle V
Is stored in the storage unit 23 in advance, but it is also possible to calculate the movement trajectory from the current position and the target position of the vehicle V.

[0046]

As described above, according to the first aspect of the present invention, the first steered angle detecting means and the second steered angle detecting means detect the steered angles of the wheels, respectively. When the outputs of the angle detecting means do not match, it is determined that one of the turning angle detecting means is out of order and the control of the actuator based on the movement locus is stopped, so that the automatic steering control based on the wrong turning angle is performed. Is performed and the vehicle is reliably prevented from moving in an unexpected direction.

According to the second aspect of the present invention,
Since the rotation angle is calculated from the terminal voltage and the energizing current of the actuator, and the steering angle of the wheel is calculated from the rotation angle of the actuator, the voltage detection means and the current detection means which are standardly provided in the electric power steering device are used. This makes it possible to detect the turning angle by utilizing it, and it is not necessary to provide a special turning angle detecting means, which can contribute to cost reduction.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a vehicle including a steering control 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 control system.

FIG. 5 is a block diagram of a second turning angle detecting means according to a second embodiment.

FIG. 6 is a diagram showing a model of an actuator.

[Explanation of symbols]

7 Steering Actuator (Actuator) 13a First Steering Angle Detecting Means 13b Second Steering Angle Detecting Means 22 Control Unit (Actuator Control Means) 23 Storage Unit (Moving Path Setting Means) 31 Voltage Detecting Means 32 Current Detecting Means 33 Rotation Angle calculating means 34 turning angle calculating means i flowing current S ₁ turning angle detecting means u terminal voltage V vehicle Wf front (wheel) Shitaact turning angle θb turning angle θref norm steering angle α rotation angle

Claims (2)

[Claims] 1. A trajectory setting means (23) for storing or calculating a trajectory of a vehicle (V) to a target position, an actuator (7) for steering a wheel (Wf), and a rotation of a wheel (Wf). turning angle detecting means for detecting steering angle (θact) and (S _1), the steering angle detected by the steering angle detecting means (S ₁₎ (θact)
And an actuator control means (22) for controlling the driving of the actuator (7) so that the steering angle coincides with the reference steering angle (θref) corresponding to the movement trajectory. The means (S ₁ ) is a first steering angle detecting means (13
a) and a second turning angle detecting means (13a), wherein the actuator control means (22) comprises the first and second steering angle detecting means (13a).
An automatic steering apparatus for a vehicle, wherein the control of the actuator (7) based on the movement trajectory is stopped when the outputs of the steering angle detecting means (13a, 13b) do not match. The actuator (7) is an electric motor, and the first and second steering angle detecting means (13a, 13
one of b) is a voltage detecting means (31) for detecting a terminal voltage (u) of the actuator (7), a current detecting means (32) for detecting a current (i) flowing through the actuator (7), Terminal voltage (u) and conduction current (i)
Rotation angle calculation means (33) for calculating the rotation angle (α) of the actuator (7) based on
The automatic steering device for a vehicle according to claim 1, further comprising: a steering angle calculating unit (34) that calculates a steering angle (θb) based on the rotation angle (α) of the vehicle.