JPS646Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a work vehicle such as a tractor that is equipped with an automatic steering function or a position control function for working equipment. This paper proposes a work vehicle in which the signal processing circuit is simplified by improving the steering sensor. Fig. 1 is a partially cutaway left side view of the tractor according to the present invention (hereinafter referred to as the proposed machine), Fig. 2 is a schematic plan view of the proposed machine showing the mounting state of the steering sensor, and Fig. 3 is the steering sensor. FIG. 4 is a schematic block diagram of the automatic steering control system. This tractor is used on cultivated land.
The boundary INT between the CDT and the uncultivated land UCT is designed to perform automatic steering as a guide for automatic steering.
Reference numeral 1 in the figure indicates a steering sensor that detects this boundary INT, and one set is provided on each side of the aircraft body, and is supported by an arm 12 that projects horizontally from the upper front part of the left and right sides of the bonnet 11. The detection surface faces a point several 10 cm in front of the landing point of the front wheels 2, 2. This steering sensor 1 includes an infrared light emitting element,
Optical sensor 1a has a built-in light-receiving element (photoelectric element), projects infrared rays emitted from the former onto a test object, captures reflected infrared rays from the test object with the latter, converts it into an electrical signal, and outputs it. , 1b, 1c, 3 pieces,
They are arranged in the horizontal direction of the machine in this order from the outside to the inside of the machine, and the outermost optical sensor 1a (on the cultivated land CTD side) only detects the cultivated land CTD, and the middle optical sensor 1b detects only the cultivated land CTD. Half of the cultivated land CTD and half of the uncultivated land UCT, and the innermost (uncultivated land)
The optical sensors 1c on the UCT side are in a state where they detect only uncultivated land UCT. The optical sensors 1a and 1c have the same specifications, but the effective light receiving area of the photoelectric element _1b1 of the optical sensor 1b is approximately twice that of the optical sensors 1a and 1c. These optical sensors 1a, 1b,
The light receiving elements 1a ₁ , 1b ₁ and 1c ₁ of 1c are connected as shown in FIG. That is, a series circuit of the photoelectric element 1a ₁ and the variable resistor 13, a series circuit of the photoelectric element 1b ₁ and the variable resistor 14, and a series circuit of the photoelectric element 1c ₁ and the variable resistor 15 are connected to the photoelectric element 1b _1. This parallel circuit and the resistor 16 are connected in parallel, with one end connected to the ground potential and the other end connected to the input terminal of the signal processing circuit 3. A potential corresponding to the difference between the sum of the short-circuit currents of the photoelectric elements 1a ₁ and 1c ₁ and the short-circuit current of the photoelectric element 1b ₁ appears at both ends of the resistor 16. The short circuit current is related to the light receiving area and the illuminance, and is approximately proportional to both. The light receiving area of the photoelectric element 1b ₁ is approximately 2 that of the photoelectric elements 1a ₁ and 1c ₁ .
Therefore, if the illuminance of each region receiving light is the same, the non-ground potential of the resistor 16, that is, the output potential of the steering sensor 1 will be approximately zero. resistance 1
3, 14, 15 are photoelectric elements 1 by adjusting the short circuit current.
It is used to make the output potential of the steering sensor 1 zero when a ₁ , 1b ₁ , and 1c ₁ face an area with the same illuminance. Therefore, when adjusted in this way, if the amount of light received by the photoelectric element 1a ₁ is A, the amount of light received by the photoelectric element 1b ₁ is 2B, and the amount of light received by the photoelectric element 1c ₁ is C, the output potential is This represents the contents of A+C-2B. Although there are differences depending on the grass growth condition, unevenness, wetness, etc. of uncultivated land UCT, in general, uncultivated land
Since the UCT has a higher reflectance than the cultivated land CTD, each photoelectric element 1a 1, 1 of the optical sensor _1a , 1b, 1c
Regarding the amount of light received by b ₁ and 1c ₁ , C of the photoelectric element 1c ₁ has the highest value, B, which is 1/2 of the value of 2B of the photoelectric element 1b ₁ , has the highest amount, and A of the photoelectric element 1a ₁ has the lowest value, which is the lowest. C
>B>A. Therefore, the optical sensors 1a, 1
The potentials A, B, and C of the respective output signals of the photoelectric elements 1a ₁ , 1b ₁ , and 1c ₁ of the photoelectric elements 1a 1 , 1b 1 , and 1c 1c are the same as those of the photoelectric elements 1a ₁ , 1b ₁ ,
Since each output terminal of _1c1 is connected as shown in Fig. 3, the potential between both terminals of resistor 16 is A+C-
2B (hereinafter referred to as P), the fourth
The signal is input to the signal processing circuit 3 as shown in the figure. Now, as shown in FIG. 4, the intermediate optical sensor 1b
If the detection area covers half of the cultivated land CTD and half of the uncultivated land UCT, 2B = A + C, so P
= 0, but the aircraft is on uncultivated land UCT [or cultivated land]
CTD], the uncultivated land UCT [or cultivated land CTD] occupies a larger portion of the detection area of the optical sensor 1b, so 2B>A+
C [2B<A+C]. Therefore, P<0 [or P
>0], and the absolute value of P is determined depending on the magnitude of the deviation from the state shown in Figure 4. In other words, P is the deviation between the steering sensor 1 and the boundary line INT, which serves as a tracing guide for automatic steering. It serves as a signal that represents the amount of energy. This also applies when the cultivated land CTD is on the left side of the aircraft. Reference numeral 4 denotes a steering angle sensor, which detects the horizontal rotation angle of the left and right front wheels 2, 2 with respect to the center line in the left-right direction of the aircraft, that is, the steering angle.
It is attached to a member such as a knuckle arm that supports horizontal rotation in conjunction with the
Specifically, a potentiometer is used. The output signal D of the steering angle sensor 4 is input to the signal processing circuit 3. This output signal D is inputted to the differential amplifier in the signal processing circuit 3 together with the above-mentioned deviation amount detection signal P to obtain a signal corresponding to the difference between the two, E=PD. Since this difference signal E is obtained by subtracting the actual steering angle from the deviation amount between the steering sensor and the boundary, it basically represents the required steering amount (a steering amount that is required more than the current state). It has become a signal. For example, in the illustrated example, even though the aircraft is moving straight (D=0), P>0 (or P<0)
In this case, E>0 (or E<0), which means that it is necessary to move the machine toward the uncultivated side (or the plowed side) by an amount corresponding to the absolute value. Further, even if P>0 (or P<0), if D=P due to automatic steering control or other factors up to that point, it means that no further steering is required. Of course, if the ideal steering condition continues, E=P=D=0. 6 is a digital data processing device;
It is a so-called microcomputer equipped with a CPU (for example, a microprocessor μPD556D manufactured by NEC Corporation), an A/D converter, a memory, an input/output interface, and the like. The output signal E of the signal processing circuit 3 is subjected to a predetermined conversion process at the input interface of the data processing device 6, and is converted into digital data according to its level at an appropriate sampling period.
Incorporated into CPU. For example, the level of E is separated and identified into seven stages, and the resultant data is imported into the CPU. The CPU of the data processing device 6 mainly performs steering control based on the signal E, and uses hydraulic drive to horizontally rotate the front wheels 2, 2 to perform steering. Table 1 shows the relationship between the level of the input signal E to the data processing device 6 and steering.

[Table] Table 1 shows the progress status of the aircraft when D=0, but as mentioned above, when E=P
-D, P has a negative deviation to the left (in the illustrated example, the uncultivated side), a positive deviation to the right (also the plowed side), and D has a positive deviation to the right (also the plowed side). Since the steering amount is set to be negative and the steering angle to the left side (also the unplowed side) is positive, when the aircraft travel range is largely deviated to the plowed side (P is large), Also, the steering has been largely shifted towards the uncultivated side. When D is large, E≧E ₃ does not necessarily hold and E ₁ >E
>-E ₁ , and we will maintain the current status without further steering.
This is because the aircraft has already been sufficiently steered towards the uncultivated side, and even if it continues in that state, the aircraft will continue to turn in a direction that eliminates the deviation towards the plowed side. . Now, the hydraulic circuit 7 operates the electromagnetic switching valve by the data processing device 6, and switches the oil path to advance and retract the rod of the double-acting cylinder.
This rod is interlocked and connected to support members for the left and right front wheels 2, 2, and as the rod moves forward and backward, the left and right front wheels 2, 2 are interlocked and horizontally rotated in the left and right directions. Therefore, the magnitude control of the steering amount is achieved by intermittently supplying pressure oil to the double-acting cylinder and by varying the duty ratio of this continuous pressure oil supply cycle. ing. That is, E≧
If E ₃ , the pressure oil is supplied in the rod's advancing direction at a large duty ratio, and if -E ₁ ≧E ≧ -E ₂ , the pressure oil is supplied in the rod's retracting direction at a small duty ratio. I am planning to do it. Reference numeral 8 denotes an input operation section, which is installed on the driver's seat in order to turn on power to the data processing device 6, switch between automatic and manual steering, and input various data and signals required for automatic steering. It is provided on the front panel 10 in front of the camera 9. This input operation section 8
When the manual steering mode is selected by the operation, the hydraulic circuit 7 is not controlled by the data processing device 6, and the steering wheel 5 fixed to the upper end of the steering column protruding from the front panel 10 is rotated. This allows for steering. That is,
The rotation of the steering wheel 5 mechanically switches the electromagnetic switching valve in the hydraulic circuit 7 to move the double-acting cylinder forward and backward. I am planning to make a turn. When performing rotary tillage with the tractor according to the present invention configured as described above, the first stroke is tilled by manual steering, and from the next stroke, the already cultivated land CTD formed in the previous stroke is tilled. Using the boundary INT between UCT and uncultivated land as a guide, automatic steering is performed as understood from the above. As detailed above, in the case of the present invention, P(=A+C-2B) is the basic information for automatic steering.
can be obtained without using arithmetic circuits such as operational amplifiers, simplifying the signal processing circuit, improving reliability by reducing the number of parts, reducing manufacturing costs, and reducing drift when using arithmetic circuits. Stable control can be performed without any risk of In addition, in the above-mentioned embodiment, each light receiving element 1a ₁ , 1
Resistors 13, 14, 1 to adjust the output of b ₁ , 1c ₁
5 was provided, but a photoelectric element 1 was provided for optical adjustment.
A configuration may also be adopted in which a diaphragm is provided on the front surface of _{a 1} , 1b ₁ , and 1c ₁ and the output is adjusted by adjusting the opening degree of the diaphragm.
In addition, in the above embodiment, an optical sensor 1b whose light receiving area is approximately twice that of the optical sensors 1a and 1c was used. It may be suppressed. Also, the photoelectric element 1b ₁ of the optical sensor 1b
As photoelectric elements 1a 1 , ₁ of optical sensors 1a, 1c
You may also use two pieces of the same type as _c1 connected in parallel. Furthermore, the present invention is not limited to automatic steering, but also controls the movement of a rotary or other working machine from side to side so that one edge of the working machine (cultivator) coincides with the boundary between cultivated and uncultivated land. The present invention can also be applied to a position control device for a working machine that avoids plowing, overlapping plowing, etc.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a partially fragmented left side view of the proposed machine, Fig. 2 is a schematic plan view of the proposed machine showing the installed state of the steering sensor, and Fig. 3 is a schematic plan view of the proposed machine showing the installed state of the steering sensor. The figure is an electric circuit diagram showing the connection state of photoelectric elements constituting the steering sensor, and FIG. 4 is a schematic block diagram of the automatic steering control system. 1...Steering sensor, 1a, 1b, 1c...Optical sensor, 1a ₁ , 1b ₁ , 1c ₁ ...Photoelectric element, 3...
Signal processing circuit, 6... Data processing device, 13, 1
4, 15...Variable resistor, 12...Arm, 16
……resistance.

Claims (1)

[Scope of utility model registration request] In a work vehicle configured to automatically control the boundary between regions with different reflectances as a work tracing guide, a first
A second photoelectric element arranged to face the other area, and a third photoelectric element arranged to face a part including the boundary between these two areas, the first and second photoelectric elements are arranged in parallel. The first and second photoelectric elements and the third photoelectric element are connected in antiparallel, and the boundary is recognized based on the output of this parallel circuit. Features: Work vehicle.