JPH07156818A - Automatic steering device for vehicle - Google Patents

Abstract

PURPOSE:To realize the smooth and stable steering which does not respond to the steering system by a minor change in the vehicle behavior. CONSTITUTION:An automatic steering device is provided with a steering actuator 2A to steer a steering wheel, a road condition recognizing means 4 to recognize the road condition, and a steering control means 5 to control thc steering actuator 2A, a deflection angle detecting means 4A is provided in the road condition recognizing means 4, and the steering control means 5 is provided with a deflection angle converting means 5B to convert the detected deflection angle value to the deflection angle value for the steering control and a control amount setting means 5A to set the control amount of the steering actuator 2A are provided. The deflection angle value converting means 5B is provided with the dead zone where the deflection angle value for the steering control is set zero when the detected deflection angle value is smaller than the prescribed value, and the hysterisis to increase/decrease the steering angle with the characteristic where the deflection angle value for the steering control is increased/decreased according to the detected deflection angle value when the detected deflection angle value is larger than the prescribed value, and the detected deflection angle value is different in the decreasing tendency and the increasing tendency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle automatic steering device suitable for use in an automobile, and more particularly to a vehicle automatic steering device capable of recognizing a reference line and a curvature of a road for smooth steering. Regarding

[0002]

2. Description of the Related Art Recently, in a steering mechanism provided for an automobile, for example, various sensors are provided on the vehicle, a control signal is set based on information from these sensors, and the steering mechanism is positively activated by hydraulic pressure or an electric motor. There have been proposed a number of automatic steering devices or vehicles equipped with automatic steering devices that automatically and automatically steer.

An example of such an automatic steering device is one in which a vehicle is equipped with a camera and a road white line can be recognized based on image information from the camera. Then, in such a device, the deflection angle (angle with respect to the white line of the vehicle) and the lateral displacement amount (lateral displacement) are detected from the road white line and the direction of the vehicle, and the target steering is performed using the deflection angle and the lateral displacement amount as parameters. The angle is set, and the steering actuator is controlled based on this target steering angle.

[0004]

By the way, it is necessary to increase the deflection angle gain in setting the target steering angle so that appropriate automatic steering can be performed when the vehicle enters a curve. However, when the deflection angle gain is increased in this way, the steering system vibrates due to the influence of the sensor (mainly the camera) detecting a slight change in the vehicle and the accuracy error in the control system such as the steering actuator. Sisters,
In particular, there is a problem that a feeling of wandering occurs when driving straight ahead or traveling in a steady circular turn.

The present invention was devised in view of the above-mentioned problems, and a vehicle in which the steering system does not respond to a slight change in the vehicle so that smooth and stable steering can be performed. An object of the present invention is to provide an automatic steering device for automobiles.

[0006]

Therefore, the vehicle automatic steering apparatus of the present invention comprises a steering actuator for steering the steered wheels of the vehicle, a road condition recognition means for recognizing a road condition in front of the vehicle, Steering control means for controlling the drive of the steering actuator so that the steering angle of the vehicle is in a required state based on the information from the road condition recognition means, and the road condition recognition means is provided with the vehicle. Deflection angle detection means for detecting the deflection angle of the vehicle with respect to the road direction ahead is provided, and the steering control means uses the detected deflection angle value for steering control based on the deflection angle information from the deflection angle detection means. A deflection angle value converting means for converting into a deflection angle value, and a control amount setting means for setting a control amount of the steering actuator based on the steering control deflection angle value converted by the deflection angle value converting means, The bias As a conversion characteristic of the angle value conversion means, a dead zone for holding the steering control deflection angle value at 0 is provided in a region where the magnitude of the detection deflection angle value is a predetermined value or less, and the magnitude of the detection deflection angle value is predetermined. In a region larger than the value, the steering control deflection angle value is increased or decreased according to the detected deflection angle value,
A hysteresis is provided to increase or decrease the steering control deflection angle value with different characteristics when the detected steering angle value tends to decrease and when the detected steering angle value tends to increase.

[0007]

In the above-described vehicle automatic steering apparatus of the present invention, the deflection angle detecting means provided in the road condition recognizing means for recognizing the road condition in front of the vehicle detects the deflection angle of the vehicle with respect to the road direction in front of the vehicle. Then, the deflection angle information is taken into the steering control means. Then, the deflection angle value conversion means provided in the steering control means converts the detected deflection angle value into a steering control deflection angle value based on this deflection angle information.

The steering control deflection angle value is set to 0 due to the dead zone in the region where the detected deflection angle value is smaller than a predetermined value, and is detected in the region where the detected deflection angle value is larger than the predetermined value. It is increased or decreased according to the angle value. The steering control deflection angle value is increased / decreased with different characteristics depending on the hysteresis setting when the detected steering angle value tends to decrease and when the detected steering angle value tends to increase. Therefore, even if the detected steering angle value changes slightly, the steering control deflection angle value does not change.

Then, the control amount of the steering actuator is set by the control amount setting means based on the steering control deflection angle value thus converted by the deflection angle value converting means, and the steered wheels of the vehicle are steered. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle automatic steering apparatus as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram schematically showing the functional configuration thereof, and FIG. FIG. 3 is a graph showing characteristics when converting to steering control deflection angle values, FIG. 3 is a schematic configuration diagram showing the schematic configuration mounted on a vehicle, and FIG. FIG. 5 is a schematic diagram showing an example of a road, and FIG. 5 is a graph for explaining the operation thereof and is a graph showing steering characteristics when the vehicle travels on a curved road shown in FIG.

As shown in FIGS. 1 and 3, the vehicle 1 has
Steering actuator 2A for steering the steered wheels 2
A camera 3 for imaging the road condition in front of the vehicle, a road condition recognition means 4 for processing image information from the camera 3, and a steering control means 5 for setting a control signal to the steering actuator 2A. Has been. That is, the vehicle 1 is an automatic steering vehicle that automatically steers the steered wheels 2 based on the image captured by the camera 3.
The steering control means 5 is provided with control amount setting means 5A that sets a control amount for controlling the steered wheels 2 based on information from the road condition recognition means 4.

A target steering angle is set as a control amount by the control amount setting means 5A, and the steering actuator 2A is operated according to the set amount of the target steering angle. Now, the normal driver performs the steering operation (changing the steering angle) mainly when the traveling direction of the vehicle 1 does not match the direction of the road on which the vehicle 1 is traveling (traveling lane). In addition to this, there may be a case where the vehicle 1 tries to correct this when the vehicle 1 shifts the traveling lane laterally (outward and leftward). It is possible that the traveling direction does not match the traveling lane direction while traveling on a curved lane, but even when traveling on a straight lane, the posture of the vehicle itself moves in the yaw direction so that the traveling direction changes from the traveling lane direction. It may come off.

Therefore, in this apparatus, steering is mainly performed so that the traveling direction of the vehicle 1 is aligned with the traveling lane direction, and a steering element for correcting the lateral position of the vehicle 1 is added thereto. It has become. Here, the road condition recognition means 4 corresponding to the driver's visual system will be described first. As shown in FIG. 1, the road condition recognition means 4 is provided with a deflection angle detection means 4A for detecting the deflection angle θ of the vehicle 1 and the lateral deviation amount Δe, and the camera 3 and the deflection angle detection means described above are provided. 4A and road condition recognition means 4 are configured. When the state of the road is captured by the camera 3, the image information from the camera 3 is taken into the deflection angle detecting means 4A, and the original image from the camera 3 is a plan view image as if seen from above (Fig. (See 1)).

The deflection angle detecting means 4A is adapted to detect the deflection angle θ at a point distant from the vehicle 1 by a predetermined distance based on the plan view image. The deflection angle θ is an angle formed by a tangent line on the road side (or center line) of the road and the vehicle center line. The deflection angle θ is detected as follows, for example. That is, a first point on the road edge (first detection point) that is separated from the vehicle by a predetermined distance, and a second point (second detection point) on the road edge that is further separated from the vehicle 1 by a predetermined amount. Is detected and the two points are connected by a straight line, and the angle θ formed by this straight line and the direction of the vehicle is detected as the deflection angle.

Although not shown, the vehicle 1 includes
A lateral deviation detecting means is provided. The lateral deviation detecting means detects how much the vehicle 1 is laterally displaced with respect to the lane center 8 and the lateral deviation amount (lateral deviation) Δe, and the deflection angle detecting means 4A detects the lateral deviation. The value of the lateral deviation Δe is detected on the basis of the planar view image converted from the current image.

In this example, the white line 12 at the center of the road is used as a reference line, and a position to the left of this reference line (= a distance that is about half the lane width) is assumed to be the center 8 of the vehicle lane. ing. Then, from this road center 8 to the own vehicle 1
The distance to the left and right center of is detected as lateral deviation. It should be noted that here, the camera 3 is installed so as to coincide with the left-right center of the vehicle 1.

Since this lateral deviation Δe is detected at a position ahead of the vehicle by a predetermined distance, the lateral deviation Δe is smaller than that in the case of a straight road when the road is curved in front of the vehicle as shown in FIG. It is detected with a large value. When the deflection angle θ and the lateral deviation Δe are detected in this way, the control amount setting means 5 sets the control command value for bringing the deflection angle θ and the lateral deviation Δe close to zero. Has become. Then, according to the control command value, the steering actuator 2A
Is controlled, and the vehicle 1 is controlled by steering control based on this command value.
The lateral deviation of the vehicle is reduced, and the traveling position of the vehicle 1 is corrected to the center of the traveling lane on the road.

Next, the steering control means 5 will be described.
As shown in FIG. 1, the steering control means 5 includes a control amount setting means 5A for finally setting a steering angle, a deflection angle value conversion means 5B, a lateral deviation gain setting section 5C, and a deflection angle gain setting section 5.
It has D. In the steering angle setting unit 5A, the steering angle δ is set as follows. That is, when the deflection angle θ and the lateral deviation Δe are detected, the lateral deviation gain setting unit 5C first determines the lateral deviation gain K based on the information of the lateral deviation Δe.
1 is set.

On the other hand, the deflection angle θ from the deflection angle detecting means 4A
Is input to the deflection angle value conversion means 5B. The deflection angle value converting means 5B is adapted to convert the detected deflection angle value θ into a deflection angle value (hereinafter referred to as steering control deflection angle value) θ ′ which is actually used for steering control. The deflection angle gain K2 is set by the deflection angle gain setting unit 5D based on the deflection angle value θ '.

In this way, the deflection angle value θ detected by the deflection angle detecting means 4A by the deflection angle value converting means 5B is converted into the steering control deflection angle value θ ′ by the steering control of the detected deflection angle value θ as it is. This is because when used as data, even if the deflection angle θ slightly changes, the steering control amount is set according to this, and the device itself becomes too sensitive. .

Therefore, in the deflection angle value converting means 5B, a dead zone is set so that a minute deflection angle value equal to or smaller than the predetermined value θ1 is maintained as 0 for the control deflection angle. As shown in FIG. 2, this dead zone is −θ1 ≦ θ ≦
It is set within the range of θ1, and when the deflection angle θ is outside this range, the steering control deflection angle value θ ′ is set according to the deflection angle. The graph of FIG. 2 is an enlarged view of the deflection angle value conversion characteristics shown in the deflection angle value conversion means 5B in FIG.

The deflection angle value converting means 5B is provided with a hysteresis for increasing or decreasing the steering angle with different characteristics when the magnitude of the deflection angle θ tends to decrease and when the magnitude of the deflection angle θ tends to increase. There is. For example, as shown in the characteristic diagram of the deflection angle value conversion means 5B in FIG. 2, when the deflection angle θ tends to increase, when the deflection angle θ becomes equal to or larger than the predetermined value θ1, the steering control deflection angle gradually increases. The value θ'increases. Then, when the deflection angle θ starts to decrease thereafter, the deflection angle value converting means 5B does not immediately decrease the steering control deflection angle value θ ′, but it is set for a while just before the deflection angle θ starts to decrease. The steering control deflection angle value θ ′ is held and then the steering control deflection angle value θ ′ is decreased.

The deflection angle value conversion characteristic shown in FIG. 2 is, as an example, θ1 = 1.0 deg, the deflection angle value conversion coefficient is 0.925, and the deflection angle θ is when the deflection angle θ tends to increase.
The deflection angle value conversion coefficient when there is a tendency to decrease is set to 1.075. Then, when the deflection angle gain setting unit 5D sets the deflection angle gain K2 based on these pieces of information, the control amount setting unit 5A sets the steering angle control amount according to the following equation (1), for example.

Steering angle control amount = K1 · Δe + K2 · θ ′ (1) When the steering angle control amount is set in this way, a command value corresponding to this steering angle control amount is given to the steering actuator 2A. The steering actuator 2A is transmitted and steers the steered wheels 2 in accordance with the command value.
Since the vehicle automatic steering apparatus as one embodiment of the present invention is configured as described above, when the state of the road is captured by the camera 3, the image information from the camera 3 is used as the deflection angle detection means 4A. The original image from the camera 3 is converted into a planar image as viewed from above. Then, the deflection angle detection means 4A detects the deflection angle θ and the lateral deviation amount (lateral deviation) Δe based on the planar view image.

When the deflection angle θ and the lateral deviation Δe are detected, the control amount setting means 5 sets the deflection angle gain K2 and the lateral deviation gain K1. That is, the lateral deviation gain setting unit 5C sets the lateral deviation gain K1 based on the information of the lateral deviation Δe. Then, when the lateral deviation gain K1 is set, this information is transmitted to the control amount setting means 5A.

On the other hand, when the deflection angle θ is detected, information on the deflection angle θ is input to the deflection angle value conversion means 5B. Then, the deflection angle value converting means 5B converts the deflection angle value θ into a deflection angle value θ ′ which is actually used for steering control, and then the deflection angle gain setting section 5D obtains this steering control deflection angle value θ ′. The deflection angle gain K2 based on this is set. By the way, the above-mentioned deflection angle value conversion means 5B is provided with a dead zone, and when the deflection angle θ is a small value equal to or smaller than the predetermined value θ1, the control deflection angle value is set to 0. When the magnitude of the deflection angle θ is larger than the predetermined value θ1, the steering control deflection angle value θ ′ is set according to the deflection angle value.

Further, in the deflection angle value converting means 5B,
Hysteresis is provided as a characteristic for setting the deflection angle θ, and the control deflection angle θ ′ is set with different characteristics when the magnitude of the deflection angle θ tends to decrease and when the magnitude of the deflection angle θ tends to increase. . In other words, due to this hysteresis characteristic, for example, immediately after the magnitude of the deflection angle θ changes from the increasing tendency to the decreasing tendency, the control deflection angle θ ′ is kept to the set value until then and then changes to the decreasing tendency. It is set to various characteristics.

Then, the deflection angle gain setting section 5D sets the deflection angle gain K2 based on the control deflection angle θ'set as described above, and thereafter, the information of the deflection angle gain K2 is controlled. It is transmitted to the quantity setting means 5A. Then, the control amount setting means 5A sets a control command value for bringing the deflection angle θ and the lateral deviation Δe close to 0 by using the lateral deviation gain K1 and the deflection angle gain K2. That is, when the gains K1 and K2 are set, the control amount setting means 5A sets the steering angle control amount according to, for example, the above equation (1).

When the steering angle control amount is set in this way, a command value corresponding to this control amount is transmitted to the steering actuator 2A, and this steering actuator 2A steers the steered wheels 2 in accordance with this command value. Let them do it. Generally, when a driver enters a curve, he or she steers at a rudder angle that corresponds to the curvature of the curve. Tends to retain horns.

Therefore, in the present invention, the value of the control deflection angle value θ'used for calculating the deflection angle gain K2 is set by the deflection angle value conversion means 5B having the dead zone and the hysteresis as described above. , The vehicle 1 does not react excessively sensitively to a slight change in the detected steering angle θ caused by the influence of a disturbance accompanying the traveling of the vehicle 1 (for example, the sway of the vehicle 1 or the like), and stable steering is performed. You can get it. Thus, it is possible to eliminate the feeling of wandering during traveling, and to make the steering of the vehicle 1 more natural. Further, due to such a characteristic of the deflection angle value converting means 5B, an automatic steering characteristic closer to driver steering can be obtained.

When the vehicle is traveling on a curved road as shown in FIG. 4 by setting the steering angle control amount as described above, FIG.
It is possible to obtain steering characteristics as shown in. Here, the line a shown in FIG. 5 is a steering angle characteristic when the deflection angle gain K2 is directly set from the detected deflection angle θ without using a dead zone or hysteresis (hereinafter referred to as normal automatic steering). The line b is the steering angle characteristic of the automatic steering in this device, and the line c is the steering characteristic of the driver steering.
The horizontal axis of FIG. 5 represents time and the vertical axis represents steering angle.
A, B, and C in FIG. 5 correspond to points A, B, and C in FIG.

As shown in FIG. 5, the steering characteristic at the point A is almost the same as that of the lines a, b, and c, but after passing through the curve at the point B, the steering wheel is operated by the normal automatic steering shown by the line a. The corners vibrate and the vehicle 1 has a feeling of wandering. On the other hand, as shown by the line b, in the automatic steering of the present device, the vibration of the steering wheel angle is reduced, and the characteristics can be made almost the same as those of the driver steering (line c).

Further, the point C in FIGS. 4 and 5 indicates the vicinity of the exit of the curve, but as shown in FIG. 5, in the characteristic of the automatic steering of this device, the turning back appears with some delay, After all, it is possible to approach the driver steering characteristics. On the other hand, in the normal automatic steering, as shown by the line a, there is no delay in returning the steering wheel, so that the steering feeling is unnatural.

As described above, when this device is used, vibration of the steering wheel angle immediately after steering is eliminated due to the dead zone provided in the deflection angle value converting means 5B, and the feeling of wobbling of the vehicle 1 at the time of steady circle turning, straight traveling, etc. is eliminated. Will be able to prevent. Further, due to the hysteresis provided in the deflection angle value conversion means 5B, the steering after exiting the curve has almost the same characteristics as the driver steering, and natural steering characteristics can be obtained.

[0035]

As described in detail above, according to the vehicle automatic steering apparatus of the present invention, the steering actuator for steering the steered wheels of the vehicle and the road condition recognition means for recognizing the road condition in front of the vehicle. And a steering control means for controlling the drive of the steering actuator so that the steering angle of the vehicle is in a required state based on the information from the road condition recognition means, and the road condition recognition means, Deflection angle detection means for detecting the deflection angle of the vehicle with respect to the road direction ahead of the vehicle is provided, and the steering control means steers the detected deflection angle value based on the deflection angle information from the deflection angle detection means. Based on the deflection angle value conversion means for converting the deflection angle value for control and the deflection angle value for steering control converted by the deflection angle value conversion means,
A control amount setting means for setting a control amount of the steering actuator is provided, and as a conversion characteristic of the deflection angle value converting means, a steering control deflection angle value is set in a region where the magnitude of the detected deflection angle value is a predetermined value or less. A dead zone to hold at 0 is provided,
In a region where the magnitude of the detected deflection angle value is larger than a predetermined value, the deflection angle value for steering control is increased or decreased according to the detected deflection angle value to increase or decrease when the magnitude of the detected steering angle value tends to decrease. With the configuration that hysteresis is provided to increase or decrease the steering control deflection angle value with different characteristics depending on the tendency,
Steering does not respond to a slight change in the vehicle, for example, vibration of the steering wheel angle immediately after steering is reduced, the occurrence of vehicle fluttering is prevented, and smooth and stable steering characteristics are obtained. Further, the steering characteristic after exiting the curve can be approximated to the driver steering characteristic, and a natural steering characteristic can be obtained.

[Brief description of drawings]

FIG. 1 is a functional block diagram schematically showing a functional configuration of an automatic vehicle steering system as an embodiment of the invention.

FIG. 2 is a graph showing an example of conversion characteristics of a detected deflection angle value in the vehicle automatic steering apparatus as one embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a schematic configuration of an automatic vehicle steering system as one embodiment of the present invention mounted on a vehicle.

FIG. 4 is a diagram for explaining the operation of the vehicle automatic steering device as one embodiment of the present invention, and a schematic diagram showing an example of a curved road.

5 is a graph for explaining the operation of the vehicle automatic steering apparatus as one embodiment of the present invention, which is a graph showing steering characteristics when the vehicle travels on a curved road shown in FIG. 4. FIG.

[Explanation of symbols]

 1 Vehicle 2 Steering Wheel 2A Steering Actuator 3 Camera 4 Road Condition Recognition Means 4A Deflection Angle Detection Means 5 Steering Control Means 5A Control Amount Setting Means 5B Deflection Angle Value Converting Means 5C Side Shift Gain Setting Section 5D Deflection Angle Gain Setting Section 8 Own Vehicle Lane Center 12 White line at the center of the road

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Aono 5-3-8, Shiba, Minato-ku, Tokyo Within Mitsubishi Motors Corporation (72) Inventor Kiichi Yamada 5-33-8, Shiba, Minato-ku, Tokyo Mitsubishi Automotive Industry Co., Ltd.

Claims (1)

[Claims] 1. A steering actuator that steers the steered wheels of a vehicle, a road condition recognition unit that recognizes a road condition ahead of the vehicle, and a steering angle of the vehicle based on information from the road condition recognition unit. And a steering control means for controlling the drive of the steering actuator so that the vehicle is in a required state, and the road condition recognizing means detects the deflection angle of the vehicle with respect to the road direction ahead of the vehicle. And a deflection angle value conversion means for converting the detected deflection angle value into a steering control deflection angle value based on the deflection angle information from the deflection angle detection means, and the deflection angle value. And a control amount setting unit for setting a control amount of the steering actuator based on the steering control deflection angle value converted by the conversion unit, and the detected deflection angle is set as a conversion characteristic of the deflection angle value conversion unit. Is provided with a dead zone for holding the steering control deflection angle value at 0 in a region where the magnitude is smaller than a predetermined value, and in a region where the magnitude of the detection deflection angle value is larger than a predetermined value, Hysteresis is provided to increase / decrease the steering control deflection angle value and increase / decrease the steering control deflection angle value with different characteristics depending on whether the detected steering angle value is decreasing or increasing. Characterized by that
Vehicle automatic steering system.