JPS641B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a running vehicle, and more particularly to a running vehicle equipped with a non-contact obstacle detection sensor at the front of the vehicle body.

Conventional unmanned vehicles of this type, such as unmanned lawn mowers, have measures such as sensing obstacles in front of the vehicle and stopping the vehicle in order to prevent danger and collisions. is necessary,
Such means require a sensor that can reliably detect obstacles and that does not malfunction. Non-contact sensors such as photo sensors and ultrasonic sensors are used as such sensors.

By the way, the non-welding type obstacle detection sensor with the above-mentioned conventional structure does not detect the obstacle by actually coming into contact with the obstacle like the contact type obstacle sensor, but rather detects the obstacle by sensing it from a certain distance away. Since it can detect obstacles, it has the advantage of greater freedom in traveling speed and better work efficiency.

However, since it is a non-contact sensor that detects obstacles, it is not possible to accurately detect the location of the obstacle. The disadvantages of this approach are that work efficiency deteriorates and the driving course unnecessarily deviates significantly from the desired driving course because the driver stops the vehicle or performs fixed avoidance control using a fixed amount of steering. .

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to use a non-contact obstacle detection sensor, but with as little steering as possible depending on the position of the obstacle. To provide a traveling vehicle that can reliably avoid obstacles.

In order to achieve the above object, a traveling vehicle according to the present invention includes a plurality of obstacle detection sensors arranged side by side in the left-right direction of the vehicle body in order to detect the position of the obstacle in a plurality of stages in the left-right direction of the vehicle body. The present invention is characterized in that it is provided with means for automatically determining the amount of steering to avoid the obstacle based on the result of detecting the position of the obstacle by the sensor.

Due to the above characteristic structure, the following excellent effects have been achieved.

In other words, the position of an obstacle can be sensed without contact, and the steering can be performed automatically with the amount of steering that corresponds to the position of the obstacle, so no matter where the obstacle is located in front of the vehicle, the steering can be done reliably. In addition to being able to continue driving while avoiding
Since there is no waste in the amount of steering required to avoid obstacles, there is an effect that control efficiency is improved.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a lawn mowing vehicle as a vehicle capable of running unmanned. A lawn mowing device 4 equipped with a disc-shaped cutting blade is suspended between the front wheels 2 and rear wheels 3 of a vehicle body 1 so as to be movable up and down. Ultrasonic sensors 5A and 5B as a non-contact obstacle sensing sensor 5 having a configuration described later are provided at the front of the vehicle.

Further, the vehicle body 1 is provided with a tracing sensor 6 for detecting the boundary between the mowed field and the unmown field, which is the boundary between the driving areas.
A, 6B, and a fifth wheel 7A is provided as a distance sensor 7 that generates one pulse per unit traveling distance in order to continuously detect the distance traveled by the vehicle body 1.

Normally, the front wheels 2, 2 are configured to be steered wheels by a predetermined amount in the left-right direction by the hydraulic cylinder 8, based on the boundary detection results of the copying sensors 6A, 6B.

On the other hand, when an obstacle is detected by the ultrasonic sensors 5A and 5B, the tracing sensor 6
The configuration is such that the travel control by A and 6B is interrupted to perform obstacle avoidance control.

The copying sensors 6A and 6B are configured as a pair of two optical sensors S ₁ and S ₂ having the same configuration, respectively, and as shown in FIG. 9 at a predetermined interval d
A pair of light-emitting elements _P1 and a light-receiving element _P2 are provided on the inner facing surfaces of the sensor frame 9, and the light-emitting elements
The structure is configured to determine the boundary between an unmowed field and a mown field by sensing the presence or absence of grass introduced as the vehicle body ₁ travels between S1 and the light receiving element _S2 . be.

Then, based on the time difference in turning on the optical sensors S ₁ and S ₂ constituting the copying sensors 6A and 6B and the vehicle body movement distance (x) during that time, the approach angle to the boundary ( θ) can be determined.

θ=tan ^-1 d/x ...(i) On the other hand, the ultrasonic sensors 5A and 5B each have the same configuration, and transmit ultrasonic waves intermittently over a predetermined range in front of the vehicle body. , by receiving reflected waves from the obstacle during this intermittent transmission, it senses the obstacle and also detects the distance to the obstacle based on the time required to transmit and receive the ultrasonic wave. . Then, the obstacle sensing area X ₁ ,
It is arranged so that it partially overlaps X ₂ .
Therefore, by combining the obstacle sensing results of the two sensors 5A and 5B, three sensing areas A ₁ ,
It is possible to determine in which range of A ₂ or A ₃ the obstacle A is located.

That is, as shown in the sensing position determination table in Figure 5 below, if only sensor 5A senses an obstacle, it will be placed in the front left side of the vehicle body, that is, area _A1 , and if only sensor 5B senses an obstacle, it will be placed in the front right side of the vehicle body. In other words, in area A ₃ , both sensors 5A, 5
When B senses an obstacle, it determines that there is an obstacle in front of the center of the vehicle, that is, in area _A2 .

Then, based on the position of the obstacle determined in this manner, a steering amount (M) for driving the vehicle while avoiding the obstacle is determined.

Below, each sensor 5A, 5B with the above configuration,
A control system that controls the running of the vehicle body 1 based on detection signals from 6A, 6B, and 7 will be described.

As shown in FIG. 3, the control device 11 is configured as a microcomputer having an input interface 12, an arithmetic device 13, and an output interface 14 as main parts, and each of the sensors 5A, 5B, 6A, 6B. , 7, the arithmetic unit 13 outputs a control signal for steering the front wheels 2, 2.
4 to drive the electromagnetic valve 15 of the hydraulic cylinder 8 and operate a transmission 16 that transmits power from the engine E to the rear wheels 3, 3.

As shown in FIG. 4, normally the mown area 17A and the uncut area 17 of the copying sensors 6A, 6B are
Tracing travel control is performed to automatically travel along the boundary 17C of B.

On the other hand, during this tracing run, there is an obstacle A in front of the vehicle body 1.
, and when either of the ultrasonic sensors 5A, 5B detects the obstacle A, as described above,
The speed change device 16 is operated to reduce the traveling speed, and the position of the obstacle is detected based on the sensing position determination table shown in FIG. 5, and the corresponding steering amount (M) is determined. The vehicle is controlled so that the vehicle avoids this.

Obstacle avoidance control will be explained below.

When the ultrasonic sensors 5A and 5B detect the obstacle A, as described above, the traveling speed is reduced to a predetermined value, and the vehicle approaches the obstacle A until the distance to the obstacle A reaches a predetermined distance (l ₁ ). The position of the obstacle is determined based on the table shown in FIG. 5, and the steering amount (M) is determined.

Then, the front wheels 2, 2 are steered toward the mowed land 17A side, that is, in the left direction in the case of the running direction shown in FIG. The moving distance (l) is measured by counting, and when a predetermined distance (l ₂ ) is reached, the front wheels 2, 2 are returned to a neutral state, and the vehicle is further driven straight for a predetermined distance (l ₃ ).

Next, the front wheels 2, 2 are steered in the opposite direction with a steering amount equal to the steering amount (M) determined based on the table (Fig. 5), and the moving distance (l) is measured. ₄ ) After running, return the front wheels 2, 2 to the neutral state, drive straight, and change the running direction to return to the unmoved area 17B (to the right in FIG. 4).

Thereafter, after the optical sensor S ₂ arranged on the outside of the vehicle body 1, which constitutes the copying sensors 5A and 5B, detects the uncut land 17B, the optical sensor S ₁ arranged inside the vehicle body 1 detects the uncut land 17B. The moving distance (l) during sensing is measured by the distance sensor 7,
The approach angle (θ) is calculated based on equation (i) above.

Then, based on the calculated approach angle (θ), the steering amount (M) determined based on the table is corrected.

Furthermore, while measuring the moving distance (l), after driving the vehicle diagonally straight on the uncut land 17B for a predetermined distance (l ₅ ), the steering amount (M') is corrected based on the approach angle (θ). Already mowed land 1 with the steering amount
Operate the steering in the direction of 7A, drive the specified distance (l ₆ ), and then repeat the same steering amount (M')
The vehicle travels a predetermined distance (l ₇ ) while performing reverse steering, and then the obstacle avoidance control is completed and the transmission 16 is returned to the normal state in order to return to the normal working speed.

After that, the machine is automatically caused to travel in a predetermined direction along the boundary between the mown field 17A and the unmown field 17B using normal tracing travel control.

According to the above explanation, if there is an obstacle A in front of the vehicle body 1, it can be reliably avoided with the smallest possible steering amount, regardless of its position and without interrupting the vehicle's travel. Moreover, when the vehicle body 1 returns to the uncut land 17B again, the approach angle (θ) is detected and the steering amount is corrected, so that the subsequent tracing control is started under good conditions, so there is no waste. Steering operation is no longer required, allowing for stable driving control.

In FIG. 3, R is a potentiometer that detects the steering amount (M) of the front wheels 2, 2.

Further, FIG. 6 is a flowchart showing the operation of the control device 11.

[Brief explanation of drawings]

The drawings show an embodiment of a traveling vehicle according to the present invention,
Figure 1 is an overall plan view of the lawn mowing vehicle, Figure 2 is a front view of the main parts of the scanning sensor, Figure 3 is a block diagram of the control system, Figure 4 is an explanatory diagram of obstacle avoidance control,
FIG. 5 is an obstacle position determination table, and FIG. 6 is a flowchart showing the operation of the control device. 1...Vehicle body, 5...Non-contact obstacle detection sensor, 5A, 5B...Ultrasonic sensor.

Claims (1)

[Claims] 1 Non-contact obstacle detection sensor 5 on the front of the vehicle body 1
A traveling vehicle equipped with
A plurality of the obstacle detection sensors 5 are arranged in parallel in the left and right direction of the vehicle body 1 in order to detect obstacles in multiple stages in the left and right direction. A running vehicle characterized by being provided with a means for automatically determining a steering amount to avoid the above.