JPH01160402A - Seedling line detector in rice seedling transplanting machine - Google Patents

Abstract

PURPOSE:To obtain a smooth virtual line with reduced error by imaging a plurality of the places where seedlings have been planted, obtaining individual centers of gravity of individual binary-coded areas to know the positions of centers of gravity in individual areas from the adjacent 3 or more centers of gravity. CONSTITUTION:A plurality of the places to which seedlings haven been planted are imaged and binary-coded to know the centers of gravity of the individual areas. Groups are constituted by combining 2 or more adjacent areas along the seedling line and the center of gravity is calculated every group. Then, a virtual line is calculated to the coordinates of the center gravities in the group.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to agricultural work using a rice transplanter or the like to run a rice transplanter or the like substantially parallel to so-called planted seedling rows, which are already planted in a field and lined up in a substantially straight row. This invention relates to the structure of a planted seedling row detection device for automatic steering that allows the machine to travel.

[Conventional technology]

Conventionally, when planting seedlings in a field using a rice transplanter, the rice transplanter is equipped with a planting mechanism at appropriate intervals on the left and right sides of the rice transplanter, and the planting mechanism that moves up and down as the rice transplanter advances moves the seedling mat on the seedling stand. Since the seedlings are divided into appropriate numbers of plants and planted in the field, the seedlings are planted at appropriate intervals along the direction of movement of the rice transplanter. It is well known that the seeds can be planted in multiple rows at appropriate intervals in the left and right direction.

Japanese Patent Application Laid-Open No. 62-61509 discloses a prior art technology for an automatic steering device that enables the rice transplanter to run approximately parallel to rows of seedlings that have already been planted in the field. A color video camera is used to image an appropriate area of the row of planted seedlings in the adjacent areas, and this imaged screen information is binarized to extract the area corresponding to the seedling location for each planting. After that, a straight line is approximately calculated from the row of the plurality of regions by processing such as Hough transform, and the horizontal deviation and lateral deviation with respect to this calculated virtual straight line and an arbitrary reference line and reference point such as the vertical and horizontal center line of the imaging screen are calculated. It is proposed to perform steering control of the aircraft so that the tilt deviation is within a certain allowable range.

[Problem that the invention seeks to solve]

When specifying this virtual straight line, for planting multiple pieces of binarized image information, store the coordinates of the area corresponding to the seedling location, calculate a line segment passing through the coordinates for each area coordinate,
A process (Hough transform process) is performed to define these multiple line segments as a Hough value (ρ) and an angle (θ) from a predetermined formula expressed in a polar coordinate system, and the frequency of taking the same Hough value (ρ) is calculated in two dimensions. It is counted as a histogram, and its maximum value is the Hough value (
ρ) and the angle (θ), the virtual line of the row of planted seedlings is specified.

When specifying this virtual straight line, when performing approximate linearization calculations using the Hough transform, even if there are large variations in the coordinates of the area corresponding to the seedling location, the approximate virtual line can be calculated with a certain degree of smoothness. However, it is necessary to use a determinant including trigonometric functions in the calculation formula for the line segment passing through each coordinate, and the calculation software for this is complicated and the calculation time is too long. If the traveling speed of the rice transplanter is increased, the line segments cannot be identified from the calculation results in time, and automatic follow-up steering to travel in parallel along adjacent rows of planted seedlings becomes impossible. Therefore, since the running speed of the rice transplanter must be slowed down, there is a problem in that the efficiency of seedling planting work is reduced.

In addition, a management machine that applies fertilizer or sprays chemicals at an appropriate time after planting seedlings may perform the work while moving along the rows of seedlings that have already been planted. The same problem as described above also occurs when a steering device is installed.

The present invention aims to solve this problem.

[Means to solve the problem]

In view of the above, the present invention provides an image capturing means for capturing an image of a seedling location in a row of planted seedlings that have already been planted along the side of an agricultural machine such as a rice transplanter, and an image information provided by the image capturing means to determine each seedling. Planting is carried out using a binarization means that specifies the seedling location as a region, determines the center of gravity of each of the binarized target regions, and then calculates the center of gravity of the three or more adjacent center of gravity positions along the direction of movement of the agricultural machine. The imaginary line of the planted seedling row is determined by a centroid position determining means for determining the centroid of each group from the group, and an imaginary line calculation means for approximating the imaginary line from the centroid positions of the plurality of groups. .

[Action/effect of the invention]

As pre-processing to perform virtual line approximation calculation, each planting in the planted seedling row is determined by determining the center of gravity of the area corresponding to the seedling location, and the approximately center point of each area of the finite area is specified as coordinates. can do.

Next, three or more of the calculated center of gravity positions along one row of planted seedlings constitute one group, and the center of gravity position of the group is determined for each group. By calculating the position of the center of gravity of the group, even if the area of seedlings for each planting varies from side to side in the direction of movement of the agricultural machine, the center of gravity of the group will be located within the area surrounding the group, and the center of gravity of the group will be located within the area surrounding the group. The variation in the left and right direction is reduced.

In this way, by performing approximate calculations of the virtual line based on the position of the center of gravity of the group with little variation, it is possible to obtain an even smoother virtual line, and the software for calculating the position of the center of gravity of the group is simple. Therefore, not only straight virtual lines, but also virtual lines such as quadratic curves can be easily calculated, and various virtual lines can be calculated using the least squares error estimation method without following the Hough transform described above. It has the effect of being executable.

According to the present invention, the virtual line can be calculated quickly as a whole, and a smooth virtual line with few errors can be obtained, so that automatic steering control can be performed quickly, accurately, and with good followability. have an effect.

〔Example〕

Hereinafter, an example applied to a rice transplanter will be described.
A traveling machine is supported by rear wheels 4.4 on both the left and right rear sides, and a multi-row seedling planting device consisting of a seedling platform 5 and a plurality of planting mechanisms 6 is installed at the rear of the traveling machine 1. 7 is attached via a link mechanism 8 so as to be able to move up and down.

The power of the engine 9 mounted on the upper surface of the frame 2 of the traveling aircraft l is transmitted to both the front and rear axles 3 and 4 via the clutch 10 and the transmission case 11, and is transmitted via the PTO shaft 12 protruding from the traveling mission case 11. power is transmitted to the seedling planting device 7. In addition, the code 13 is the clutch 1
0 is an ON/OFF actuator, 14 is an actuator for traveling speed change, and 15 is an actuator for changing the circumferential speed of the PTO shaft.

A steering gear box 17 is provided on the upper surface of the traveling aircraft 1 in front of the pilot seat 16, and a steering shaft 19 inserted into the steering column 18 is attached to the upper end of a steering column 18 that stands up from the steering gear box 17. The control handle 20 is attached.

Reference numeral 21 denotes a left and right long transmission case, to which the front wheels 2, 2 are attached via knuckles 22. The bracket 21a, which is U-shaped in plan view, is connected via a swing shaft 21C rotatably supported by a support member 21b at the center of the lower surface of the frame 2, so that it can swing horizontally and vertically. ing.

The steering device 26 includes a steering arm 24 which is horizontally rotatably mounted on a rotation fulcrum shaft 23 erected from one side of the transmission case 15;
4, a pair of left and right tie rods 25, 25, a hydraulic cylinder 26, a steering control valve 27, and the steering control valve 27.
It consists of two pitman arms that can freely swing back and forth of the steering gear box 7 that operates the steering gear box 7.

One ends of the pair of left and right tie rods 25, 25 are connected to the arm portion 24a of the steering arm 24 extending in the front-rear direction of the frame 4 via a ball joint, respectively.
Both tie ronds 25, 25 are extended along the transmission case 15 to the left and right of the movement of the traveling machine body l, and each other end thereof is a knuckle arm 2 extending forward from each of the knuckles 22.
9. Connect to 29 so that it can swing freely.

A steering control valve 27 is connected rearward via a ball-and-socket joint to a support shaft 30 of an arm extending inwardly from the steering arm 24 toward the side surface of the frame 2. The spool and the pitman arm 28 are connected via a connecting rod 31.

Further, the rear end of a hydraulic cylinder 26 disposed substantially parallel to the outer surface of the frame 2 is connected to the support shaft 30 via a ball joint, while the front end of the piston rod 26a is connected to the frame via a ball joint. 2 is connected to a bracket horizontal shaft 32 protruding from the outer surface.

The steering control valve 27 and the hydraulic cylinder 26 are each connected by a hydraulic hose, while hydraulic pressure is sent to the steering control valve 27 from a hydraulic pump 33 driven by the engine 5.

Then, the pitman arm 28, which swings in accordance with the rotation angle of the steering handle 10, moves the spool of the steering control valve 27 forward and backward, causing the piston rod 26a in the hydraulic cylinder 26 to move in and out.
4, the directions of both left and right front wheels 2.2 are changed.

This hydraulic cylinder 26 is connected to a planted seedling row detection device 37 which will be described later.
It is also driven by an electromagnetic solenoid type control valve 34 operated by a central control device 35 for automatic steering and driving that outputs an output signal in response to a signal from the fulcrum shaft 23. This is executed by detecting the rotation angle of the steering arm 24 with a potentiometer 36 attached to the steering arm 24.

The actuator 13 for ON/OFF of the clutch lO, the actuator 14 for traveling speed change, the actuator 15 for changing the circumferential speed of the PTo shaft are operated by the central control device 35.

The planted seedling row detection device 37 includes an imaging means 40 for imaging an object.
and an image processing device 41 for processing the captured image and outputting necessary information (data), and a schematic flowchart of its operation is shown in FIG. 9 and FIG. 1θ.

The imaging means 40 is capable of imaging a detection target and outputting the screen as an electrical signal, such as a color video camera, and is an imaging means incorporating a two-dimensional MO≦imaging element or two-dimensional CCD imaging element. The image formed through the lens is sensed by each photoelectric element arranged in a two-dimensional array, and the information of one screen can be output as an electrical signal. In this case, the display elements that constitute one image are called pixels.In other words, when one image is divided into minute area segments, each element becomes a pixel.

In the two-dimensional image sensor, each image sensor corresponds to one pixel, and for example, one screen is sampled into 256×256 pixels.

The image processing device 41 reads the data of the image capture screen 42 captured by the image capture means 40, and based on the data, transfers the planted seedling location (NAE) to another field scene location 4 such as a mud surface.
After the binarization extracted from 3, the center of gravity of each of the binarized target areas is calculated from the position data of the identified target areas using a predetermined calculation method using software built into the image processing device 41. a center of gravity position determining means for determining the position and then determining the center of gravity of each of three or more target areas from a group of three or more target areas along the traveling direction of the rice transplanter; and an imaginary line that is straight or curved proximal to the center of gravity of the plurality of groups. A calculation means is used to determine the virtual line K of the row of planted seedlings.

In this embodiment, when configuring a captured image on a color screen, the RGB color system [red (R), green (G
), blue (B) color light is used as the primary color light, white is obtained by adding the color light)], the characteristics of the field scene are extracted from the signals of each color component: red component, green component, and blue component. Green (G) for the total signal output (R + G + B = 1)
When the signal output ratio of the component is above a predetermined value, it is determined that it is a seedling, and the area (A) is segmented from other parts of the screen using a set of multiple pixels (Segmentation). Binarization processing is performed. Execute.

Alternatively, binarization may be performed using color difference processing in which a portion of the image where the color difference image data (GB) obtained by subtracting the blue component from the green component of the color signal is output at a certain level or more is determined to be a seedling.

As described above, each binarized area (A) is considered to have an appropriate planar area, and can be regarded as a set of a plurality of pixels corresponding to the area of each area (A) on the imaging screen 42. , the level of the pixels corresponding to the area (A) is set as "1" and the level of the pixels in the other part 43 is set as "0" as the binarized value.

On the other hand, the position coordinates of each area (A) must be specified as preprocessing to determine a virtual line passing near the position of each area (A).

Therefore, the positional coordinates of each area (A) on the imaging screen 42 are represented by the center of gravity of the area of the area (A).

Various calculation methods can be considered for determining the center of gravity position, but in this example, the area is (
The coordinates of the center of gravity are determined using a method similar to so-called area contraction, such as replacing the level V-1 part of the pixel corresponding to the area of A) with level v = 0 in a spiral pattern from the outer periphery of the area. It is decided.

Next, as described above, the coordinates of the center of gravity (Xi, Yj)
(i, j = L2.3...) is calculated area (
Among A), three areas (A) adjacent to each other along the direction of the planted seedling row constitute one group, and for each group, the center of gravity position of the group (XGi, YGi) (i = 1 .2
,3. ) is calculated.

For example, as shown in FIG. 7 (Xl, Yl).

The center of gravity position (XGI, YGI) of one group consisting of the three coordinates (X2.Y2) and (X3.Y3) is determined by the geometrical formula YG1=(Y1+Y2+Y3)/3. In this way, the center of gravity position of each group (XG1.YGl)
.

(XG2.YG2), ” (XGi, YGi)
After calculating this, an imaginary line K that approximates the coordinates of the center of gravity of this group is calculated.

As one method of approximate calculation to find the virtual line K,
As is generally well known, there is a method based on least squares error estimation, which is based on multiple coordinates (XGi, YGi
) (i = 1.2.3..., n), the function to be sought is F (x) = aO+alx +a2x"+a3
x3+...-+anx'', the problem is the same as finding a function F(x) such that This shows the case where the virtual line K is assumed to be a straight line.

In calculating the virtual line K in this way, each planting determines the center of gravity of the seedling location (NAE) and calculates the center of gravity of a group consisting of the three center of gravity positions.
Even if the seedling locations in the planted seedling row vary from side to side, the row based on the center of gravity of the group will be smoother, and the error in the approximation calculation of the virtual line will be reduced, and the approximate straight line and approximation It is no longer necessary to use complex calculation algorithms such as Hough transform to obtain curves.
It is possible to increase the calculation speed and realize quick automatic steering control.

After image processing is performed in this way, the image processing device 41 sets the intersection of the vertical center line (■) and the horizontal center line H of the imaging screen 42 as a reference point (0, O), and When the center line ■ is set as the reference line along the aircraft's traveling direction, the inclination angle (θ) of the virtual line with respect to the vertical center line ■ and the reference point (
Lateral shift (δ) is calculated as the distance from the horizontal center line H (0, 0) to the intersection with the virtual line.

And the image processing device 41 according to the flowchart of FIG.
In the calculation, it is determined whether the inclination angle (θ) and lateral deviation (δ) of the virtual line are within a predetermined error tolerance range (within the diagonal line shown by the two-dot chain line in Fig. 8). When the error is within the allowable range, a signal of information (data) necessary for control of the central controller 35 is output, and the electromagnetic solenoid of the steering control valve 34 is activated to rotate the steering arm 24 at the steering Nu+l. The hydraulic sill 26 that changes the angle is driven to perform corrective steering, and automatic steering control is executed so that the error falls within a predetermined error tolerance range.

Next, when planting seedlings at dusk,
A backlight prevention means that prevents the imaging means 40 from imaging a portion of the field scene 44 where sunlight is totally reflected will be described.

FIG. 11 is a schematic explanatory diagram showing the relationship between the imaging means 40, the depression angle sensor 45, and the sunlight 46, when the imaging means 40 is imaging the field scene 44 at an angle of depression (inferior). , assuming that the sunlight 46 is totally reflected on the water surface of the field scene 44, similar to the so-called backlighting phenomenon in a camera, very bright light (approximately white) will appear on the imaging screen 42 of the imaging means 40 due to total reflection of the sunlight. light) reflected light 4
6' is included, and even if there is a seedling planting point (NAE) in the totally reflected part, the said point (NAE) cannot be determined.

Therefore, the depression angle sensor 45 is attached via a bracket or the like so that it cannot move up and down integrally with the imaging means 40, and the two are configured to be rotated together by a servo motor 50. In that case, the depression angle sensor 45 and the imaging means 40 are arranged so that the depression angles (α) formed with respect to the field scene 44 are substantially parallel straight lines 46' and 47. Note that one sensor 45a and the other sensor 45b in the depression angle sensor 45 are set at an appropriate angle (β) with respect to the straight line 47.
It is slanted to have a As a result, when the light energy input to both sensors 45a and 45b is approximately equal, the field scene 44 is illuminated with light incident along the straight line 47.
It is determined that total reflection of sunlight is occurring.

The output signal of this depression angle sensor 45 is input to a comparator 1548 equipped with an amplification circuit, and when it is determined that total reflection has occurred as described above, the number - POMOK 50 attached to the rice transplanter is adjusted as appropriate via the drive circuit 49. When driving and mounting the imaging means 40 integrally with the depression angle sensor 45, the angle is changed upward or downward by an appropriate angle (r).

This prevents the image capturing means 40 from capturing an image of a so-called backlit field scene part, and also allows an image of a seedling area to be captured for planting other than the area where total reflection occurs, even in the early morning and at dusk. It is possible to carry out seedling planting work.

Note that the servo motor 50 is equipped with a potentiometer so that the depression angle of the imaging means 40 can be recognized.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and Fig. 1 is a plan view of a riding rice transplanter, Fig. 2 is a side view, Fig. 3 is a plan view of main parts of the steering device, and Fig. 4 is a steering/travelling diagram. An action explanatory diagram including a block diagram and a hydraulic circuit of the automatic control device, Fig. 5 is a diagram of the imaging screen, Fig. 6 is a diagram of the binarized imaging screen, and Fig. 7 is a diagram of the center of gravity position and the virtual line. FIG. 8 is a diagram showing the relationship between the virtual line on the imaging screen and the reference, FIG. 9 and FIG. 1θ are schematic flowcharts, and FIG. 11 is an explanatory diagram of the backlight prevention means. 1... Traveling body, 2... Frame, 3, 4...
... Wheels, 5 ... Seedling stand, 6 ... Planting mechanism, 7
...Seedling planting device, 8...Link mechanism, 9...
Engine, 11...Mission case, 17...
・Steering gear box, 20...Control handle, NAE...Seedling location for planting, K...Virtual line,
23...Rotation fulcrum shaft, 24...Steering arm, 26...Hydraulic cylinder, 34...Steering control valve, 35...Central control device, 36...Potentiometer 40... Imaging means, 41... Image processing device, 42... Imaging screen, A... Area, 45
... Depression angle sensor, 49... Drive circuit. Manual Correction (Spontaneous) January 27, 1986 Special a'Fiig '4゛Jll j (l, Al: 1
ffl sound 1. 1 display Special 1 No. 62-322182 2, Name of invention Device for detecting planted seedling rows in rice transplanter 3, ? ! Relationship with the case to be corrected
1-32 Chayamachi, Kita-ku, Osaka City Name
(685) Yanmar Agricultural Machinery Co., Ltd. 4, Agent Address ■530 1121 Kita 2-chome Tenjinbashi, Kita-ku, Osaka Akira 'lfJ7Mill, Specification originally attached to the WM document, page 1, No. 1
Correct "Detailed description of the invention" in line 6 to "Detailed description of the invention".゛(2), ``This invention'' in line 18 of page 1 is corrected to ``This invention is''.

Claims (1)

[Claims] (1) An imaging means for taking images of a plurality of planted seedling locations in a row of planted seedlings that have already been planted along the side of an agricultural machine such as a rice transplanter; The binarization means identifies the area as a region, determines the center of gravity position of each binarized target area, and then calculates the center of gravity of each of the three or more adjacent groups of center of gravity along the direction of movement of the agricultural machine. A planted seedling row in an agricultural working machine, characterized in that a virtual line of the planted seedling row is determined by a center of gravity position determination means for determining the center of gravity, and a virtual line calculation means for approximating a virtual line from the center of gravity positions of the plurality of groups. Detection device.