JPS595B2 - Automatic travel control device for tillers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for automatically driving a tiller along the boundary line between uncultivated land and cultivated land during tillage work.

The present inventors first inspected the boundary line between uncultivated land and cultivated land in a field using a photoelectric sensor attached to the body of the tiller, and from the output detected the positional deviation of the tiller relative to the boundary line (from the correct tilling position). We have developed a control device that detects the amount of deviation in the field and controls the steering of the tiller in accordance with the detected signal to make the tiller travel correctly along the boundary line.

The travel position detection device, which is the main part of this travel control device, recognizes the boundary line by utilizing the considerable difference in infrared reflection level between uncultivated and cultivated land, and detects boundaries within the inspection range using the photoelectric sensor. Only when there is a clear boundary between uncultivated land and cultivated land can deviations in the driving position from that boundary be detected.

However, in actual fields, a situation sometimes occurs in which the photoelectric sensor is unable to detect the displacement of the traveling position.

This undetectable state can occur when the tiller deviates significantly from the boundary line, causing the boundary line to be outside the sensor inspection range.Also, even if the tiller is correctly aligned with the boundary line, it may occur if the tiller is not properly aligned with the boundary line. This also occurs when the boundary line is optically obscured by traces, or when the boundary line that should serve as the driving reference line disappears where it intersects with other plowing marks. In the conventional prototype device, there is a control method that stops the tiller running when the above-mentioned undetectable condition occurs, and a control method that does not stop the tiller but cancels automatic steering control and leaves it to manual control by the driver. Two types of control methods were used.

The former control method is a safe method because it never causes the tiller to run out of control.

However, even if the cause of the undetectable area, such as the above-mentioned scorched straw marks or intersections with other plow marks, is in an extremely short section, the tiller will stop each time the undetectable condition occurs. This requires a starting operation, which is extremely inconvenient in practice. In addition, since the sensor inspects the front in the direction of travel, the tiller becomes unable to inspect before the correct position at which it should end at the tilling end point, causing the tiller to stop, causing the same inconvenience as above. . In the latter control method, the tiller moves at the wheel angle at the time the undetectable state occurs between the time the automatic control is released and the time the driver consciously starts manual control. Since the wheel angles are not known, in many cases the vehicle runs at a considerable angle from the line of ascension it should follow, making it impossible to perform the desired plowing work.

In other words, when the automatic crawling leg is operating normally, the cultivator's vehicle body is running parallel to and along the boundary line, but in such a state, it does not respond to the positional deviation detection signal described above. This is achieved by rotating the steering wheels left and right. Therefore, when an undetectable state occurs, the angle of the steered wheels is not necessarily along the boundary line. In an actual field, the steering wheel is always turned left and right even when the vehicle is traveling along a straight boundary line. Therefore, in the case of this invention, in actual fields, there are many places where detection is impossible due to relatively short sections such as burnt straw marks and intersections with other tillage marks, and in normal tillage work, boundaries are extremely difficult to detect. It is very rare to draw a sharp curve, and even if the angle of the steering wheel is not constant at the time when detection is not possible, the tiller's body is aligned correctly along the boundary line due to the automatic control up to that point. By paying attention to the attitude of the tiller, when an undetectable state occurs, the angle of the steering wheel is forcibly controlled to make the tiller go straight.

In other words, in many cases, even if an undetectable state occurs, if the tiller is moved straight, the tiller becomes detectable again and automatic follow-up tilling can be performed continuously. However, it is of course not convenient in all cases to move the tiller in a straight line, so it is sufficient to take measures as described in the following embodiments. Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

The boundary line sensor main body 4, which is composed of three photoelectric sensors 4A, 4B, and 4C as shown in FIG. 1, is attached to the side of the tiller 5 as shown in FIG. Inspect the field scene ahead.

Each sensor 4A. 4B and 4C have the same configuration; an infrared light emitting element (light emitting diode) 1 attached to the center of a lens 3 at the front end opening of the cylinder emits infrared rays toward the field, and the reflected infrared rays are reflected by the lens 3. The light is collected and sent to respective light receiving elements (photodiodes) 2A, 2B. It is designed to receive light at 2C. These three sensors 4A, 4B,
4C are arranged in a line horizontally in the front and back direction of the tiller 5, and when the tiller 5 is in the correct position with respect to the boundary line of uncultivated land (that is, along the boundary line, (when the soil is in a position where it can be cultivated without creating any gaps or overlaps)
The inspection field of view is set so that the sensor 4A inspects the uncultivated ground, the sensor 4C inspects the cultivated ground, and the central sensor 4B inspects the boundary of the uncultivated land.
A, b, and c in FIG. 2 indicate the field of view of each sensor 4A, 4B, and 4C. The infrared reflectance of a field is high in uncultivated land with a relatively flat surface, and low in cultivated land that is roughly plowed. Therefore, in the above-mentioned correct running condition, the output level of the light receiving element 2A is the highest, the output level of the light receiving element 2C is the lowest, and the output level of the light receiving element 2B is an intermediate value between the above two output levels. . From this state, when the tiller 5 is displaced with respect to the boundary line and the inspection field of view b of the sensor 4B shifts from the boundary line to the uncultivated land side, the light receiving element 2B changes accordingly.
The output level of the light receiving element 2B increases, and conversely, when moving to the cultivated land side, the output level of the light receiving element 2B decreases. In this way sensor 2
The amount of deviation of the tiller 5 with respect to the boundary line can be determined from the output of B, but it is not possible to absolutely detect the amount of deviation from only one sensor. In this state, the amount of deviation of the tiller 5 can be detected by comparing the outputs of the two sensors 2A and 2C with the output of the central sensor 2B. Therefore, the sensor 4A that inspects uncultivated land in a normal detection state is referred to as an uncultivated land sensor, the sensor 4C that inspects cultivated land is referred to as an cultivated land sensor, and the central sensor 4B is referred to as a boundary sensor. FIG. 3 is a block diagram showing the electrical configuration of the device according to the present invention.

As shown in the figure, the infrared light emitting element 1 of each sensor is connected to the oscillator 6.
Each light receiving element 2 is driven intermittently at a constant cycle by the output of
A. The outputs of 2B and 2C are respectively sent to synchronous amplifiers 7A. 7B
, 7C, the signals are detected and amplified in synchronization with the oscillator 6, and input to buffer amplifiers 8A, 8B, and 8C, respectively.
Further, the differential amplifier 9 calculates the difference (VA-VB) between the output VA of the uncultivated land sensor 4A and the output VB of the boundary sensor 4B.
The difference (VB-Vc) with the output Vc of C is determined, and the difference (VA-Ve) is similarly determined in the differential amplifier 11. Furthermore, the difference VA+Ve-2VA) between the output of the differential amplifier 9 and the output of the differential amplifier 10 is calculated by the differential amplifier 12. However, the gain of this differential amplifier 12 is the same as that of the differential amplifier 11.
The smaller the difference (VA-Vc), the larger the gain of the differential amplifier 12 becomes, thereby obtaining an output that is automatically gain-controlled with respect to fluctuations in the reflection level in the field. ing. The output of the differential amplifier 12 (VA
+■c-2VB) corresponds to the difference between the intermediate value ■Δ±X1 of the output VA of the uncultivated land sensor 4A and the output vc of the cultivated land sensor 4C, and the output ■B of the boundary sensor 4B. As mentioned above, the output becomes the amount of deviation of the tiller 5 from the boundary line.

In addition, in the above-mentioned traveling position deviation detection device, as described above, the state in which the uncultivated land sensor 4A is inspecting the uncultivated land and the cultivated land sensor 4C is inspecting the cultivated land is the state in which the normal position can be detected. The inspection area of the uncultivated land sensor 4A shifts to cultivated land, or the inspection area of the cultivated land sensor 4C shifts to uncultivated land, and the relationship between the outputs of both sensors becomes VA≦■e
This is a state in which normal position detection cannot be performed.

This is detected by the comparator 13 in FIG. 3, and when VA≦■c, its output is inverted from ``0'' to ``1'', and the ``1'' signal becomes an undetectable signal. When a traveling position shift can be detected and the output of the converter 13 is 10''5, the analog gate 14 is off and the analog gate 15 is turned on by the output of the inverter 16.

In this state, the detection voltage Δv of the running position deviation output from the differential amplifier 12 is inputted to the differential amplifier 17. The output voltage VX of a wheel angle detector 18 consisting of a potentiometer linked to the steering wheel of the steering wheel 5 is input to the other input side of the differential amplifier 17, and the difference between the two input voltages (VX - Δ■ ) is supplied to the main controller 19. The main control device 19 is mainly composed of a microcomputer,
In addition to the steering cylinder 20 that rotates the steering wheel, this device is responsible for electrically controlling each part of the tiller.

The steering control by the main control device 19 is performed by calculating the deviation (VX - △V) between the detection voltage △V of the running position deviation and the detection voltage VX of the wheel angle.
The steering wheel is rotated to the right or left depending on the sign of the steering wheel, and the greater the absolute value of the deviation (VX- to V), the greater the rotation speed of the wheel. As a result, the steering wheels are controlled so that the deviation (VXΔV) is always minimized, and the tiller 5 is driven while maintaining a predetermined relationship with the boundary line. Regarding this control, for example, Japanese Patent Application No. 54-27
It is disclosed in detail in the No. 546 specification. Therefore, as described above, when the detection of the traveling position deviation becomes impossible and the output of the comparator 13 becomes "1", the analog gate 15
is off, the analog gate 14 is turned on, and the output voltage Vo of the reference voltage generation circuit 21 is input to the differential amplifier 17 instead of V to the output of the differential amplifier 12.

This reference voltage Vo is set to be equal to the detection voltage output from the differential amplifier 12 when the running position deviation is zero, that is, when the cultivator 5 is in the correct positional relationship with respect to the boundary line. It is set in advance. Therefore, the above-mentioned steering control by the main controller 19 is based on the output of the differential amplifier 117 (
(2) When the steering wheel is rotated based on X-Vo), the steering wheel is returned to an angle parallel to the vehicle body and stopped, and the tiller 5 moves straight. In other words, since one input of the differential amplifier 17 continuously becomes "no position shift", steering control is performed to keep the cultivator 5 in that state so that it moves straight. Furthermore, the undetectable signal output from the comparator 13 is output from the timer 2.
2, and this timer 22 outputs an abnormality signal to the main controller 19 when the undetectable signal is manually input for a predetermined period of time or more.

When the above-mentioned abnormality signal is input to the main control device 19, in addition to issuing an alarm to the driver with a buzzer or lamp, the main control device 19 also stops driving as in the conventional case or cancels automatic control. . Thereby, it is possible to prevent the tiller 5 from continuing to move straight even though the undetectable state continues for a long time. Figure 4 schematically shows a field where there is an undetectable area due to burnt straw marks near the almost linear boundary line 4 between uncultivated land and cultivated land.

In the case of the tiller 5 to which the present invention is applied, when the field of view A, b, c of the sensor body 4 reaches the burnt straw mark @ while traveling along the boundary line (a), the comparator 13 outputs an undetectable signal. As described above, the tiller 5 is controlled to travel straight, and as a result, it travels along the extension of the boundary line 4 that it has been following up to that point. If the boundary line 4 is not greatly curved near this roasted straw mark @, the field of view A of the sensor body 4
．． When b and c pass the Akatsukiwara mark @, they become undetectable again, and the control returns to the output of the differential amplifier 12. Considering that the situation shown in Fig. 4 is very common in actual fields, by applying the present invention, it is possible to proceed with the tillage work smoothly without any traces of automatic follow-up tillage. Note that in the above embodiment, the second
As shown in the figure, the fields of view A, b, and e of each sensor are arranged horizontally in a row, but unlike this, the field of view c of the cultivated land sensor 4C is set in front of the other two fields of view A, b, There is also a configuration that actively causes an undetectable state considerably before the tilling end point, and if the present invention is applied to this, control at the tilling end point will be extremely good.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of the structure of three sensors in the present invention, Fig. 2 is a plan view showing the relationship between the field of view of the tiller and the soil, and Fig. 3 is an example of the electrical configuration of the device of the present invention. The block diagram shown in FIG. 4 is a diagram for explaining the effects of the present invention. 1... Infrared light emitting element, 2A, 2B, 2C...
...Photodetector, 3...Lens, 4A...
... Uncultivated land sensor, 4B... Boundary sensor,
4C... Already cultivated land sensor, 4... Sensor body, 5... Cultivator, 9, 10, 11, 12,
17... Differential amplifier, 13... Comparator, 18... Wheel angle detector, 21...
...Reference voltage generation circuit.

Claims (1)

[Claims] 1. An uncultivated land sensor whose field of view is set to inspect the infrared reflection level of the uncultivated land while the tiller is in a predetermined tilling position along a substantially straight boundary line between the uncultivated land and the cultivated land; A boundary sensor whose field of view is set to inspect the infrared reflection level at the boundary between uncultivated land and cultivated land, and a cultivated land sensor whose field of view is set to inspect the infrared reflection level of the cultivated land are attached to the tiller's vehicle body. The system detects the running position deviation of the tiller with respect to the boundary line from the output of these three sensors, and also controls the angle of the steering wheel of the tiller according to the detection signal to correct the above running position deviation. In a device that controls the running of the power tiller, it is determined based on the output of the sensor whether the correct detection of the running position deviation is impossible, and when the detection impossible state occurs, the angle of the steered wheel is forcibly adjusted. An automatic travel control device for a tiller, characterized in that the tiller is controlled to move straight.