JPH0550931A - Automatic steering device of vehicle - Google Patents

Abstract

PURPOSE:To carry out an adequate automatic steering without giving an abnormal feeling to a driver. CONSTITUTION:Between the first member 2A and the second member 2B of a steering shaft, a delaying means 23 to delay the startup of the handle steering angle more than the startup of the steering angle of the wheels while interlocking the steering angle of the wheels and the handle steering angle in the automatic steering operation is provided. The delaying means 23 is provided with a hydraulic cylinder 21 linked to the first member 2A, and an elastic body member 22 linked to the second member 2B. The piston rod 21a of the hydraulic cylinder 21 and the elastic body member 22 are connected making both lengths regulatable. In an automatic steering operation, the projecting amount of the piston rod 21a is reduced so as to reduce the rigidity. Consequently, a 'kickback type' element to hurt a driver is moderated, and no abnormal feeling is given to the driver.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic steering system for a vehicle that performs steering to avoid interference 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 a collision by steering is calculated and collision avoidance is performed by automatic steering, the steering wheel steering wheel follows the steering angle of the wheels by the automatic steering. The corner rises, but since it is performed regardless of the driver's intention, the driver may feel a sense of discomfort.

The present invention provides an automatic steering apparatus for a vehicle, which is capable of performing appropriate automatic steering without giving a discomfort to a driver.

[0005]

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

According to a first aspect of the present invention, a delay means for delaying the rise of the steering angle of the steering wheel from that of the steering angle of the wheel while interlocking the steering angle of the wheel and the steering angle of the steering wheel during automatic steering. Is provided. In the invention of claim 2, the delay means is a hydraulic cylinder connected to one member of the steering shaft divided into a first member and a second member, and an elastic body connected to the other member. And a piston rod of the hydraulic cylinder and the elastic member are connected so that the connecting length can be adjusted.

[0007]

According to the invention of claim 1, the delay means delays the rise of the steering angle of the steering wheel later than that of the steering angle of the wheels while interlocking the steering angle of the wheels and the steering angle of the steering wheel during automatic steering. Therefore, the driver is less likely to feel a sense of discomfort due to automatic steering.

According to the second aspect of the present invention, the piston rod of the hydraulic cylinder and the elastic member are coupled so that the coupling length can be adjusted. Therefore, by adjusting the coupling length, the steering wheel steering angle delay can be delayed. You can adjust the amount.

[0009]

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

In FIG. 1 showing a schematic structure, a steering wheel 1 has a pinion 3 (see FIG. 7) at a lower end of a steering shaft 2 which meshes with a rack portion 5 (see FIG. 7) of an axle 4. It can be steered. Further, an automatic steering cylinder 6 is provided for the axle 4,
Automatic steering is also possible. Then, the position sensor 8 for detecting the position of the axle 4 by the controller 7
In response to the output of the above, the two switching valves 9 and 10 and the automatic steering valve 11 are controlled, the pressure oil supplied from the oil pump 12 is supplied to the automatic steering cylinder 6, and the automatic steering is performed by the feedback control. You can do it.

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, the controller 7 includes a friction coefficient detecting means 7A for detecting the friction coefficient of the road surface by a known method, the friction coefficient detecting means 7A and the vehicle speed sensor 100.
The output of A and 100B is received, and the steering angle at the time of automatic steering is
The steering angle setting means 7B is set according to the speed of the vehicle, the friction coefficient of the road surface, or the relative speed between the vehicle and the preceding vehicle.

Further, the steering shaft 2 has a structure shown in FIG.
Further, as shown in detail in FIG. 3, a delay means 23 including a hydraulic cylinder 21 and an elastic member 22 which is a twisting element is provided in the middle thereof. That is, the steering shaft 2 is divided into a first member 2A and a second member 2B, the hydraulic cylinder 21 is attached to the first member 2A, and the tubular elastic member 22 is attached to the second member 2B. ing. And the piston rod 2 of the hydraulic cylinder 21
1a and the elastic member 22 are spline-fitted so as to be movable only in the axial direction.

Therefore, when the amount of protrusion of the piston rod 21a is large (see FIG. 4), the twist length is short and the rigidity is large, while when the amount of protrusion is small (see FIG. 5), the twist length is long. It becomes larger and the rigidity becomes smaller.

Therefore, during automatic steering, the piston rod 2
By decreasing the amount of protrusion of 1a (see FIG. 6), the torsion spring constant is reduced, and the steering wheel steering angle rises while the steering angle of the wheel and the steering wheel steering angle are interlocked during automatic steering. By delaying it by a delay means 23 more than that, the "kickback" element that may hurt the driver is alleviated, and the spring reaction force of the torsion prompts the driver to steer an appropriate steering angle. It will be.

Further, as shown in FIG. 7, a power piston 31 for power steering and a piston 32 for an automatic steering cylinder are arranged in parallel. That is, the power piston 31 slidably slides in the outer cylinder 33 integrally with the rack portion. A piston 32 is integrally formed with the outer cylinder 33, and the piston 32 is slidably slidable in an outer cylinder 34 integrally formed with the vehicle body. Always urged to the neutral position by. The power piston 31 is driven by pressure oil supplied from an oil pump 42 via a three-position four-port type valve 41. Also, the piston 32 has 2
It is driven by pressure oil supplied from an oil pump 42 via a valve 5 of a position 5 port type and a valve 44 of a 3 position 4 port type. Therefore, the drive sources for the automatic steering and the power steering are made common, and the steering is performed by the combined force of the steering force, the power steering force and the automatic steering force by the driver. The automatic steering force and the power steering force can be set separately.

At the time of automatic steering, as shown in FIG. 8, the drive of the power piston 31 is stopped by the valve 41, and only the piston 32 is operated by the valves 43, 44.
It is driven by and automatic steering is performed. At this time, for example, when a positive steering torque is detected in the automatic steering direction, a weak assist is given to the power steering. On the other hand, when the automatic steering is switched to the power steering, as shown in FIG. 9, the valve 43 is switched until the piston 32 reaches the center position, and then the valve 43 returns to the communication state, and then the power piston 31. Are driven by the valve 41, as shown in FIG.

The above-mentioned automatic steering is a steering for avoiding interference in consideration of the friction coefficient of the road surface and the motion characteristics of the vehicle from the traveling conditions of the vehicle (vehicle distance, distance between the preceding vehicle and the guide rail, etc.). A pattern is set and performed as necessary, and after the completion of automatic steering, to correct an erroneous motion caused by a deviation between the actual vehicle characteristic and the vehicle characteristic used for setting the steering pattern. , It makes a corrective steering to stabilize the vehicle.

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

In FIG. 11, when the automatic steering is started, the steering is initialized and the curvature of the corner is detected (step S1). Speed v1, road surface friction coefficient μ, left allowable range yL, and right allowable range yR are detected (step S2
). The own vehicle speed v0 and the speed v1 of the preceding vehicle are 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. 12), and 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), overtaking time T1, steering angle θH, and allowable lateral G are calculated (step S3).

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

[0023]

[Equation 1]

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

[0025]

[Equation 2]

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

[0027]

[Equation 3]

The steering angle is determined in consideration of the friction coefficient of the road surface (see FIG. 13). That is, when the friction coefficient 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. Further, as shown in FIG. 14, the greater the relative speed V, the greater the minimum inter-vehicle distance L0 required for automatic steering.

Based on these, as shown in FIG. 15, the steering pattern by automatic steering is determined. This 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.

Then, in order to check whether there is a possibility of interference, it is judged whether or not the relative speed V> 0 (step S4). When the relative speed V exceeds 0,
Since there is a possibility of interference, it is determined whether the inter-vehicle distance L1 is smaller than the warning distance (step S5). If it is smaller, an alarm (e.g., alarm lamp, alarm buzzer) is issued (step S6), and if not smaller, 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 S7).
). If it is smaller, it is necessary to avoid interference. Therefore, first, it is determined whether or not the right allowable range yR is smaller than the required lateral movement amount y0 (step S8). Therefore, it is judged whether the left allowable range yL is smaller than the required lateral movement amount y0 (step S9). If it is smaller, the rightward movement cannot be performed.
Therefore, it returns.

Also, the right allowable range yR requires a lateral movement amount y
If it is not smaller than 0, the vehicle can turn right, so the y flag is set to 1 (step S10), and it is determined in step S11 whether or not y flag = 1.

If y flag = 1, the steering pattern changing from the right direction to the left direction is automatically steered to avoid interference (step S12). If y flag = 1, from the left direction. Automatic steering is performed with a steering pattern that changes to the right to avoid interference (step S13). At this time,
The automatic steering is performed in consideration of the curvature of the corner.

Then, it is determined whether or not the overtaking time T1 has elapsed (step S14), the above-mentioned automatic steering is continued until the time elapses, and after the elapse, correction steering is performed (step S15) and the engine returns.

Then, the correction steering in step S15 is performed as shown in FIG.

After the start, 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). In addition, Kp
, Kx, Kd are constants.

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

[0040]

According to the invention of claim 1, the steering angle of the wheel and the steering angle of the steering wheel are interlocked during automatic steering, and the rise of the steering angle of the steering wheel is delayed after that of the steering angle of the wheel. The driver is less likely to feel uncomfortable due to automatic steering.

According to the second aspect of the present invention, since the piston rod of the hydraulic cylinder and the elastic member are coupled so that the coupling length can be adjusted, the steering angle of the steering wheel can be adjusted by a simple operation of adjusting the coupling length. This can be done by adjusting the delay amount.

[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 side view of a steering shaft.

FIG. 3 is an exploded perspective view of a delay unit.

FIG. 4 is an explanatory diagram showing a state of a delay unit at a normal time.

FIG. 5 is an explanatory diagram showing a state of a delay unit during automatic steering.

FIG. 6 is an explanatory diagram showing changes in torsion spring constant during automatic steering.

FIG. 7 is a diagram showing a relationship between a piston of an automatic steering cylinder and a piston of a power steering device.

FIG. 8 is a diagram showing a state of a piston of an automatic steering cylinder and a piston of a power steering device during automatic steering.

FIG. 9 is a diagram showing the states of the piston of the automatic steering cylinder and the piston of the power steering device during the transition from automatic steering to power steering.

FIG. 10 is a diagram showing a state of a piston of an automatic steering cylinder and a piston of a power steering device during power steering.

FIG. 11 is a flow chart of control for avoiding an obstacle ahead.
It is a chart.

FIG. 12 is a diagram showing a relationship between a preceding vehicle and an own vehicle.

FIG. 13 is a block diagram of steering angle calculation.

FIG. 14 is a diagram showing a relationship between a steering angle, a lateral movement distance, and an overtaking time.

FIG. 15 is a diagram showing a relationship between relative speed and minimum inter-vehicle distance.

FIG. 16 is a flowchart showing the flow of correction steering processing.

[Explanation of symbols]

 1 Steering wheel 2 Steering shaft 2A 1st member 2B 2nd member 21 Hydraulic cylinder 21a Piston rod 22 Elastic member 23 Delay means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location B62D 137: 00 (72) Inventor Takeshi Takagi 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Motor Corporation (72) Inventor Satoshi Morioka 3-1, Fuchu-cho Shinchi, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Inventor Satoru Matsuoka 3-3-1 Shinchu, Fuchu-cho, Aki-gun, Hiroshima Prefecture (72) Invention Nao Hikita No. 3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Motor Corporation

Claims (2)

[Claims] 1. An automatic steering device for a vehicle that performs steering for avoiding interference with an obstacle, wherein a steering angle is associated with a steering system while a steering angle of a wheel and a steering angle of a wheel are interlocked during automatic steering. An automatic steering apparatus for a vehicle, comprising: a delay unit that delays the rising of the vehicle from that of a wheel turning angle. 2. The delay means comprises two members, a first member and a second member.
A hydraulic cylinder connected to one member of the divided steering shaft and an elastic member connected to the other member are provided, and the piston rod of the hydraulic cylinder and the elastic member are connected so that the length can be adjusted. The automatic steering apparatus for a vehicle according to claim 1, wherein