JPH0550935A - Automatic steering device of vehicle - Google Patents

Abstract

PURPOSE:To avoid a contact securely without generating a slip and the like regardless of the variation of the friction coefficient of the road surface and the characteristics of the vehicle. CONSTITUTION:By a lateral acceleration detecting means 7A of a controller 7, the lateral acceleration is detected in a well known method. By receiving the output of the lateral acceleration detecting means 7A, a steering pattern converting means 7B controls the steering pattern according to the difference between the startup of the lateral acceleration in the automatic steering operation and a standard startup.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic steering device for a vehicle that steers to avoid contact with obstacles.

[0002]

2. Description of the Related Art Conventionally, as a guidance device for realizing collision avoidance between moving bodies moving on a plane by steering, as disclosed in, for example, Japanese Unexamined Patent Publication No. 1-124008, a vehicle and another moving body. The collision position is calculated from the position, the direction of travel, and the speed, and the route for avoiding the collision by steering is calculated,
It is known to perform steering.

[0003]

However, when a route for avoiding contact by steering is calculated and automatic steering is performed as described above, lateral G (lateral acceleration) may occur due to variations in road friction coefficient and vehicle characteristics. ) May change, and contact avoidance may not be surely performed. That is, basically, the steering pattern is determined by the friction coefficient of the road surface and the motion characteristics of the vehicle, but the friction coefficient of the road surface changes every moment, and the characteristics of the vehicle also fluctuate depending on weight and balance. .. Therefore, the desired movement of the vehicle may not always be realized by the steering pattern determined in the initial stage.

The present invention provides an automatic steering system for a vehicle that can reliably avoid contact with an obstacle regardless of variations in the friction coefficient of the road surface and the characteristics of the vehicle.

[0005]

SUMMARY OF THE INVENTION The present invention is predicated on an automatic steering system for a vehicle that performs steering to avoid contact with obstacles.

According to the present invention, a lateral acceleration detecting means for detecting lateral acceleration and an output of the lateral acceleration detecting means are provided, and a steering pattern is received according to the difference between the rising of the lateral acceleration during automatic steering and the rising of the reference. The steering pattern changing means for changing the above is provided.

[0007]

The lateral acceleration is detected, and the steering pattern is changed according to the difference between the rising of the lateral acceleration during automatic steering and the rising of the reference.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

In FIG. 1 showing a schematic structure, 1 is a steering wheel, and a pinion (not shown) at the lower end of the steering shaft 2 meshes with a rack portion (not shown) of an axle 4 for steering. It is like this. An automatic steering cylinder 6 is provided for the axle 4 so that automatic steering can be performed. And controller 7
Receives the output of the position sensor 8 that detects the position of the axle 4, and the two switching valves 9 and 10 and the automatic steering valve 1
1 is controlled to supply the pressure oil supplied from the oil pump 12 to the automatic steering cylinder 6, and the automatic steering can be performed by the feedback control.

A signal from a first vehicle speed sensor 100A for detecting the speed of the own vehicle and a signal from a second vehicle speed sensor 100B for detecting the speed of the preceding vehicle are input to the controller 7. There is. Also, the controller 7 is
Lateral acceleration detecting means 7A for detecting lateral acceleration by a known method
And a steering pattern changing means 7B which receives the output of the lateral acceleration detecting means 7A and changes the steering pattern according to the difference between the rising of the lateral acceleration during automatic steering and the rising of the reference.

This automatic steering avoids contact (interference) from the traveling conditions of the vehicle (distance between the vehicles, distance between the front vehicle and the guide rail, etc.) in consideration of the friction coefficient of the road surface and the motion characteristics of the vehicle. The steering pattern is set as necessary, and is performed as necessary, and after the completion of automatic steering, the erroneous motion caused by the deviation between the actual vehicle characteristics and the vehicle characteristics used for setting the steering pattern is corrected. In order to stabilize the vehicle, the steering is corrected to stabilize the vehicle.

Next, the control of the automatic steering by the controller 7 for avoiding the contact with the preceding vehicle will be described.

In FIG. 2, when starting, the following distance L1 between the preceding vehicle and the own vehicle, the own vehicle speed v0, and the speed v1 of the preceding vehicle
, Road friction coefficient μ, left allowable range yL, right allowable range yR
Is detected (step S1). The vehicle speed v0,
The speed v1 of the preceding vehicle is detected by a known method. Further, the distance L1 between the preceding vehicle 13 and the own vehicle 14 from the external environment recognition system such as a scan type laser radar, the angle θ from the preceding vehicle to the guide rails on both sides and the road boundary line such as a white line.
R and θL are detected (see FIG. 3), and for example, the right allowable range yR and the left allowable range yL are obtained according to the equations such as yR 〓 L1 tan θR yL 〓 Ltan tan θL.

The white line can be detected by reflection from a cat's eye or the like installed on the white line or application of image processing technology using a video camera or the like.

Then, based on these detected values, the minimum inter-vehicle distance L0 and the relative speed V (= v0 between the own vehicle and the preceding vehicle).
-V1), the overtaking time T1, the steering angle θH, and the allowable lateral G are calculated (step S2).

Here, the minimum inter-vehicle distance L0 is calculated by the following equation.

[0017]

[Equation 1]

Then, the time T1 required for steering is determined by the following equation by the lateral movement distance y0 and the allowable maximum lateral G determined by the friction coefficient of the road surface.

[0019]

[Equation 2]

Further, taking the vehicle model into consideration, the steering angle θH
Is determined based on the following formula.

[0021]

[Equation 3]

The steering angle is determined in consideration of the friction coefficient of the road surface detected by a known method (see FIG. 4). That is, when the friction coefficient μ of the road surface is small, the allowable lateral G is small. On the other hand, since the required lateral movement distance is substantially constant, the smaller the allowable lateral G, the shorter the time required for steering, and the smaller the steering angle. Also, as shown in FIG.
As the relative speed V increases, the minimum inter-vehicle distance L0 (= V · T1) required for automatic steering increases.

Based on these, as shown in FIG. 6, the steering pattern by automatic steering is determined. That is,
This automatic steering is a predetermined amount y0 before catching up with the preceding vehicle.
Steer with a sine-wave single wave steering pattern that can move laterally only.

In order to check whether there is a possibility of contact, it is judged whether or not the relative speed V> 0 (step S3).

If the relative speed V exceeds 0, there is a possibility of contact with the preceding vehicle as an obstacle, so it is determined whether the inter-vehicle distance L1 is smaller than the warning distance L2 (step S4). If it is small, an alarm (eg an alarm lamp,
An alarm buzzer) is issued (step S5), and if it is not small, it returns.

After the alarm is issued, it is determined whether the inter-vehicle distance L1 is smaller than the minimum inter-vehicle distance L0 (step S).
6). If it is small, you need to avoid contact, so
First, it is determined whether or not the right allowable range yR is smaller than the required lateral movement amount y0 (step S7). If it is smaller, the rightward movement cannot be performed. Therefore, the left allowable range yL is smaller than the required lateral movement amount y0. Is also small (step S8
), If it is small, you cannot move to the right. Therefore, it returns.

Further, the right allowable range yR is the required lateral movement amount y.
If it is not smaller than 0, the y flag is set to 1 (step S9), and if the left allowable range yL is not smaller than the required lateral movement amount y0, the process proceeds to step S10 as it is and whether or not y flag = 1. To judge.

If y flag = 1, the steering pattern changing from right to left is automatically steered to avoid contact (step S11), and if y flag = 1, from the left direction. Automatic steering is performed by the steering pattern changing to the right to avoid contact (step S12).

Then, the predicted lateral G (lateral acceleration) is calculated (step S13), and the (variation of the predicted lateral G) /
The rise α of the reference lateral G, which is (variation of the steering angle)
ask for ref. In addition, the actual lateral G is detected (step S1
4) Obtain the actual rise G of the lateral G, which is (actual lateral G variation) / (steering angle variation). Then, it is determined whether or not the absolute value of the reference lateral rise Gref of the lateral G is larger than the actual absolute value of the lateral rise G of the lateral G (step S15). If it is large (see Fig. 7 (a)), it may not be possible to avoid it in the lateral direction, and there is a risk of contact, so change the steering pattern to avoid contact (see Fig. 7 (b)) and increase the steering angle. On the other hand (step S16), if it is not large (see FIG. 8 (a)), an excessive lateral G may occur, which may cause a spin. Therefore, the steering pattern should be changed to prevent the spin from occurring. (See FIG. 8B), the steering angle is reduced (step S17).

The correction of the steering pattern is carried out by detecting the lateral G with a sufficiently short sampling time (for example 50 msec) with respect to the steering cycle (for example 2 seconds).
It is possible to prevent deviation from the target lateral G.

Then, it is determined whether or not the overtaking time T1 has elapsed (step S18), the automatic steering is continued until the time elapses, and after the elapse, the correction steering is performed (step S19) and the engine is returned.

The correction steering in step S19 is performed as shown in FIG.

After the start, first, the yaw angle .theta.2 after the start of automatic steering is detected (step S21). This detection is
The output from the yaw rate gyro is integrated.

Then, a difference θref between the yaw angle θ1 before the start of automatic steering and the yaw angle θ2 after the start of automatic steering is calculated (step S22). Then, the automatic steering angle θH is detected based on the difference θref (step S23).

Then, it is determined whether or not the absolute value of the automatic steering angle θH is smaller than the steering angle play θ0 (step S2).
Four). If it is smaller, it is not necessary to steer, and the process is ended as it is. If it is not small, it is determined whether or not the automatic steering angle θH is positive (step S25). If it is positive, the steering angle θH is steered to the left (step S26), while if it is not positive, the steering angle θH is steered to the right (step S27).

In this way, the correction steering is performed, and the deviation between the traveling direction at the start of steering and the traveling direction after the completion of automatic steering is eliminated.

[0037]

According to the present invention, since the steering pattern is changed according to the difference between the rise of the lateral acceleration during automatic steering and the rise of the reference, the influence of the variation of the friction coefficient of the road surface and the vehicle characteristics is affected. The contact avoidance can be performed reliably and with good stability without receiving the contact.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a configuration of an automatic steering device for a vehicle.

FIG. 2 is a flowchart of a control for avoiding a front obstacle.

FIG. 3 is a diagram showing a relationship between a preceding vehicle and an own vehicle.

FIG. 4 is a block diagram of steering angle calculation.

FIG. 5 is a diagram showing a relationship between a steering angle, a lateral movement distance, and an overtaking time.

FIG. 6 is a diagram showing a relationship between relative speed and minimum inter-vehicle distance.

FIG. 7 is a diagram showing an example of temporal changes in lateral G and steering angle.

FIG. 8 is a diagram showing another example of temporal changes in lateral G and steering angle.

FIG. 9 is a flowchart showing the flow of processing for correction steering.

[Explanation of symbols]

 7 Controller 7A Lateral acceleration detection means 7B Steering pattern changing means 13 Leading vehicle (obstacle) 14 Own vehicle

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location B62D 105: 00 111: 00 113: 00 137: 00 (72) Inventor Yasunori Yamamoto Fuchu, Aki-gun, Hiroshima Prefecture 3-1-1 Shinchi, Machida Co., Ltd. (72) Inventor Tomohiko Adachi 3-1-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd.

Claims (1)

[Claims] 1. An automatic steering apparatus for a vehicle that performs steering for avoiding contact with an obstacle, wherein a lateral acceleration detecting means for detecting lateral acceleration, and an output of the lateral acceleration detecting means are used for automatic steering. An automatic steering apparatus for a vehicle, comprising: steering pattern changing means for changing a steering pattern according to a difference between a rise in lateral acceleration and a rise in a reference.