JPH0550933A - Automatic steering device of vehicle - Google Patents

Abstract

PURPOSE:To prevent a generation of spin and the like especially on a downhill road and the like, by providing a steering angle converting means to convert the steering angle according to the amount of the slope of the road, in a steering control system to control the steering in order to avoid a contact with an obstacle. CONSTITUTION:An automatic steering cylinder 6 is provided to an axle 4, and depending on the output of a position sensor 8 to detect the position of the axle 4, two change-over valves 9 and 10, and an automatic steering valve 11 are controlled by a controller 7 to control the pressure oil fed to the automatic steering cylinder 6 from a hydraulic pump 12, so as to carry out the automatic steering by a feedback control. In this case, a slope detecting means 7A to detect the slope of the road, and a steering angle converting means 7B are provided. And according to the detected amount of the slope, the steering angle is converted. That is, the larger the car speed, the smaller the steering angle, and in a downhill road, the steering angle is reduced much more than in a normal condition, and thereby, a generation of spin and the like are prevented.

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 guiding 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, the own vehicle and other moving bodies. It is known that the collision position is obtained from the position, the traveling direction, and the speed, the route for avoiding the collision is calculated by steering, and the steering is performed.

[0003]

However, when a route for avoiding contact by steering is calculated and collision avoidance is performed by automatic steering as described above, for example, when the road is downhill, the steering angle is large. , There is a risk of causing spin and the like.

The present invention provides an automatic steering system for a vehicle capable of preventing the occurrence of spin or the like on a downhill grade.

[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 first aspect of the present invention, there is provided gradient detecting means for detecting the gradient of the road and steering angle changing means for receiving the output of the gradient detecting means and changing the steering angle according to the magnitude of the gradient of the road. The configuration.

According to the invention of claim 2, the gradient detecting means for detecting the gradient of the road, and the output of the gradient detecting means,
Steering speed changing means for changing the steering speed according to the grade of the road is provided.

[0008]

According to the invention of claim 1, the steering angle is changed in accordance with the magnitude of the gradient of the road. That is, when the vehicle speed increases, the steering angle decreases, but when the vehicle is descending, the steering angle becomes smaller than in the normal case.

According to the second aspect of the invention, the steering speed is changed according to the magnitude of the road gradient. That is, when the vehicle is descending, the steering speed is suppressed more than in the normal case.

[0010]

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 a lower end of a 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. Further, a gradient detecting means 7A for detecting the gradient of the road on which the vehicle is traveling, and a steering angle changing means 7 for receiving the output of the gradient detecting means 7A and changing the steering angle according to the magnitude of the gradient.
This automatic steering equipped with B is designed for avoiding contact after considering the friction coefficient of the road surface and the motion characteristics of the vehicle from the traveling conditions of the vehicle (distance between the vehicles, distance between the front vehicle and the guide rail, etc.). To set the steering pattern, perform it as necessary, and to correct the erroneous motion caused by the deviation between the actual vehicle characteristics and the vehicle characteristics used to set the steering pattern after the completion of automatic steering. However, the steering is corrected to stabilize the vehicle.

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

In FIG. 2, at the start, the following distance L1 between the preceding vehicle and the host vehicle, the host vehicle speed v0, the friction coefficient μ of the road surface, the left allowable range yL, the right allowable range yR, and the downhill slope φ are detected. (Step S1). The vehicle speed v0 is detected by a known method. Further, from the external environment recognition system such as a scan type laser radar, the distance L1 between the preceding vehicle 13 and the own vehicle 14 and the angle θR from the preceding vehicle to the guide rails on both sides and the road boundary line such as a white line. , 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.

Further, the downward gradient φ is detected by a vertical gyro or the like from the body posture angle. Then, based on these detected values, the minimum inter-vehicle distance L0, the relative speed V (= v0-v1) between the own vehicle and the preceding vehicle, 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 longer the time required for steering,
The steering angle becomes smaller. Further, as shown in FIG. 5, as the relative speed V increases, the minimum inter-vehicle distance L0 (= V · T1) required for automatic steering increases.

Further, as shown in FIG. 6, when the vehicle speed v0 increases, the steering angle θH decreases accordingly, but
In case of downhill (see Q), do not spin etc.
The steering angle is set to be smaller than that when traveling on flat ground (see P). Further, the steering speed may be changed instead of or together with the steering angle.

Based on these, as shown in FIG. 7, the steering pattern by automatic steering is determined. That is, the automatic steering is performed by a sine-wave single-wave steering pattern that can move laterally by a predetermined amount y0 before catching up with the preceding vehicle.

In order to check whether there is a possibility of contact, it is judged whether the relative speed V> 0 (step S3).

If the relative speed V exceeds 0, there is a possibility of contact, so it is determined whether the inter-vehicle distance L1 is smaller than the warning distance L2 (step S4). If it is smaller, an alarm (eg alarm lamp, alarm buzzer) is emitted (step S
5) If not small, return.

After the alarm is issued, it is determined whether the inter-vehicle distance L1 is smaller than the minimum inter-vehicle distance L0 (step S6). If it is smaller, it is necessary to avoid contact, so first it is judged whether or not the right allowable range yR is smaller than the required lateral movement amount y0 (step S7).
Since the rightward movement is not possible, it is judged whether or not the left allowable range yL is smaller than the required lateral movement amount y0 (step S8), and if it is smaller, the rightward movement cannot be performed. 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 the y flag is 1, the steering pattern that changes from the right direction to the left direction is automatically steered to avoid contact (step S11). If the y flag is not 1, the left direction is changed. Automatic steering is performed by the steering pattern changing to the right to avoid contact (step S12).

Then, it is judged whether or not the overtaking time T1 has elapsed (step S13), the automatic steering is continued until the time elapses, and after the elapse, the correction steering is performed (step S14) and the engine is returned.

The correction steering in step S14 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, the difference .theta.ref between the yaw angle .theta.1 before the start of automatic steering and the yaw angle .theta.2 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 judged whether or not the absolute value of the automatic steering angle θH is smaller than the play amount θ0 of the steering angle (step S
twenty 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 the above embodiment, the downhill is detected, and the steering angle is directly determined based on FIG. 6 according to the downhill, but instead, the downhill and the normal case are used. Alternatively, the control may be changed.

That is, it is possible to determine that the vehicle is down when the downward acceleration decreases and the forward acceleration increases by using the biaxial accelerometers in the vertical and longitudinal directions. It should be noted that when the vehicle speed is normal and the vehicle speed is constant, the downward acceleration is g and the forward acceleration is 0.

In a normal case, the method shown in FIG. 4 is used, but in the case of a downhill slope, the maximum allowable lateral width G needs to be lower than in a normal case because the frictional force between the tire and the road surface is small. .. As a result, the time required for steering increases, and the load on the front part of the vehicle increases and the load on the rear part decreases due to the downward slope. Therefore, the stability factor A in the equation is reduced, and the steering angle is reduced as compared with the normal traveling on level ground.

[0038]

According to the first aspect of the present invention, since the steering angle is changed according to the magnitude of the road gradient, spin or the like can be prevented when the vehicle is descending.

According to the invention of claim 2, the steering speed is changed instead of the steering angle. Therefore, like the invention of claim 1, it is possible to prevent spin or the like when the vehicle is descending a slope. Become.

[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 relative speed and minimum inter-vehicle distance.

FIG. 6 is a closed bell showing the relationship between the vehicle speed and the steering angle.

FIG. 7 is a diagram showing a relationship between a steering angle, a lateral movement distance, and an overtaking time.

FIG. 8 is a flowchart showing a flow of processing for correction steering.

[Explanation of symbols]

 1 Steering wheel 7 Controller 7A Gradient detecting means 7B Steering angle changing means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B62D 105: 00 111: 00 113: 00 117: 00 137: 00 (72) Inventor Takeshi Takagi Hiroshima Prefecture 3-1, Shinchi, Fuchu-cho, Aki-gun Mazda Co., Ltd. (72) Inventor Satoshi Morioka, 3-1, Shin-chi, Fuchu-cho, Aki-gun, Hiroshima Prefecture (72) In-house, Satoshi Matsuoka, Fuchu-cho, Aki-gun, Hiroshima Prefecture No. 3 in Mazda Co., Ltd. (72) Inventor Naoyuki Hikita No. 3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd.

Claims (2)

[Claims] 1. An automatic steering device for a vehicle, which steers to avoid contact with an obstacle, comprises: slope detecting means for detecting a slope of a road; An automatic steering apparatus for a vehicle, comprising: a steering angle changing unit that changes a steering angle according to the steering angle. 2. An automatic steering device for a vehicle that steers to avoid contact with an obstacle, comprising: slope detecting means for detecting a slope of a road; and an output of the slope detecting means to determine the magnitude of the slope. An automatic steering apparatus for a vehicle, comprising: a steering speed changing means for setting a steering speed according to the steering speed.