CN103714563B - A kind of boundary of curve type farmland operation area modeling method - Google Patents

Abstract

The invention discloses a kind of boundary of curve type farmland operation area modeling method, gather the key point of boundary of curve type farmland operation area, find out point and the point of abscissa value minimum that in all key points, abscissa value is maximum, utilize cubic spline function to set up coboundary model and lower boundary model.Barrier summit in the border in shaped form farmland operation region and farmland operation region can be recorded and draw out by the present invention accurately; thus the operating personnel for agricultural plant protection machine provides farmland operation region accurately, for the path of agricultural plant protection machine and trajectory planning and calculate farmland working area and provide reliable foundation.

Description

Boundary modeling method for curved farmland operation area

Technical Field

The invention relates to a boundary modeling method for a curved farmland operation area.

Background

With the continuous development of science and technology, the adoption of modern machinery to replace manual labor has become a popular trend in various industries. As a traditional agricultural big country, China has a wide cultivated land area, however, the traditional manual operation mode is still adopted in the aspect of domestic farmland operation at present. The pesticide spraying adopts a manual spraying mode, the mode is not only low in efficiency, but also has great harm to the mind and body of operators, and therefore, advanced technology is urgently needed to change the phenomenon. Agricultural plant protection machines have come to the end, however, all plant protection machines are operated manually nowadays, and the spraying area and boundary of the farmland are judged completely by the eyes of operators, so that the phenomena of misjudgment, spray leakage and spray increase are difficult to avoid. Therefore, if the operator can obtain the accurate boundary of the farmland operation area, when the unmanned helicopter operates, the path and the flight path are displayed on the display in real time, and the operator can judge the position of the airplane according to the flight path, so that the problems of misjudgment, missed spraying and excessive spraying are solved to a great extent, and the safety of agricultural spraying is greatly improved. The key to this problem is to accurately obtain the boundary information of the farmland. Therefore, a good modeling method for the boundary of the farmland operation area is urgently needed to solve the practical problem.

The invention discloses a method for collecting farmland key vertex mapping images, which is invented by Beijing agricultural information technology research center and provides a method for collecting farmland key vertex mapping images. The method comprises the following steps: s₁: acquiring GPS position information; s₂: outlining the area to be measured; s₃: surveying and mapping the critical boundary vertex of the farmland, and labeling the name and the annotation of the plot; s₄: checking, prompting and dividing the farmland in real time; s₅: uploading mapping data; s₆: and acquiring a vector map.

Wherein at S₂In the method, the outline of the region to be measured is sketchedThe method comprises the following steps: sequentially calibrating and disorderly calibrating, wherein the sequential calibration sequentially calibrates the outline of the area to be tested by taking the serial number of the outline vertex as the sequence; the unordered calibration refers to automatically calibrating a polygon with the largest area and including all the contour vertices into a region contour.

In the conventional method, a vector map of a farmland is drawn, but a farmland operation area boundary is not drawn, so that a drawn farmland outline comprises two parts: a working area and a non-working area. When the farmland contour map is used in the places such as pesticide spraying path and flight path planning of an agricultural plant protection machine, the phenomenon of multiple spraying in a non-operation area can occur, and pesticides are wasted; when the method is used for calculating the farmland operation area, the phenomenon of inaccurate calculation of the operation area can occur; the traditional method does not establish a mathematical model for the boundary of a farmland area, so that a reliable basis cannot be provided for path and track planning of a farmland operation area; the top points of obstacles (such as telegraph poles, trees, signal transmitting towers and the like) which possibly exist in a farmland operation area are not marked, and when the farmland contour map is used for planning paths and flight paths for spraying pesticides by an agricultural plant protection machine and the like, the agricultural plant protection machine is possibly collided or crashed.

Disclosure of Invention

The invention aims to solve the technical problem that the prior art is insufficient, and provides a method for modeling the boundary of a curved farmland operation area, which accurately records and draws the boundary of the curved farmland operation area and the top point of an obstacle in the farmland operation area, thereby providing an accurate farmland operation area for operators of agricultural plant protection machines, and providing a reliable basis for planning the path and flight path of the agricultural plant protection machines and calculating the farmland operation area.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method for modeling the boundary of a curved farmland operation area comprises the following steps:

1) from the side of the curved farmland working areaA certain key point D of the boundary₁Starting, collecting all key points of the boundary of the curved farmland operation area in the clockwise direction, and setting a total of m key points as D₁(x₁,y₁),D₂(x₂,y₂),D₃(x₃,y₃),…,D_m(x_m,y_m) (ii) a Establishing a rectangular coordinate system, and automatically collecting one point from the m key points (every other sampling period (the reciprocal of the sampling frequency of the GPS) when the key points return to the initial position, namely the key point D₁Ending sampling point at the position) is arranged in a first quadrant of the rectangular coordinate system;

2) comparing the abscissa of the m key points to find out the key point with the maximum abscissa value and the key point with the minimum abscissa value; if the abscissa values of the plurality of key points are all the minimum values, and the plurality of key points are the first key point D₁And the last key point D_mThe key point with the first order is used as the key point with the minimum abscissa value if the key point D is the first key point₁And the last keypoint D_mIf the abscissa values are all the minimum values, the last key point is taken as the key point with the minimum abscissa value; if the abscissa values of the plurality of key points are all the maximum values, and the plurality of key points are the first key point D₁And the last key point D_mThe key point with the last order is taken as the key point with the maximum abscissa value, if the first key point D₁And the last keypoint D_mIf the abscissa values of the first and second points are all maximum values, the first key point D is determined₁As the key point with the maximum horizontal coordinate value; key point D with smallest horizontal coordinate value_iAnd the largest key point D_jRespectively serving as the left end and the right end of all key points in a rectangular coordinate system;

3) with D_iAs a starting point, D_jIs the end point; in the clockwise direction, order D_i=B₀,D_i+1=B₁,…,D_j=B_nWill be driven from D_iTo D_jEach point in turn is B₀(x₀,y₀),K,B_n(x_n,y_n) (ii) a Establishing the following upper boundary function model S_t(x)：

$S_{t\left(x\right)}=M_t\frac{{(x_{t+1}-x)}^3}{{6h}_t}+M_{t+1}\frac{{(x-x_t)}^3}{{6h}_t}+(y_t-\frac{M_t{h}_t^2}{6})\frac{x_{t+1}-x}{h_t}+(y_{t+1}-\frac{M_{t+1}{h}_t^2}{6})\frac{{x-x}_t}{h_t};$

Wherein, x ∈ [ x_t,x_t+1,],t=0,1,...,n-1；x_t、x_t+1Are respectively B₀、B_nPoint B in between_t、B_t+1On the abscissa of (a) and B_t+1Is B_tThe next point in the clockwise direction; coefficient M_t、M_t+1Solving by a catch-up method; h is_t=x_t+1-x_t；y_t、y_t+1Are respectively point B_t、B_t+1The ordinate of (a);

4) with D_iAs a starting point, D_jIs the end point; in the counterclockwise direction, let D_i=C₀,D_i-1=C₂,…,D_j=C_rEstablishing the following upper boundary function model S_r(x)：

$S_{r\left(x\right)}=M_r\frac{{(x_{r+1}-x)}^3}{{6h}_r}+M_{r+1}\frac{{(x-x_r)}^3}{{6h}_r}+(y_r-\frac{M_r{h}_r^2}{6})\frac{x_{r+1}-x}{h_r}+(y_{r+1}-\frac{M_{r+1}{h}_r^2}{6})\frac{{x-x}_r}{h_r};$

Wherein, x ∈ [ x_r,x_r+1,],r=0,1,...,m-n；x_r、x_r+1Are respectively C₀、C_m-nPoint C in between_r、C_r+1On the abscissa of (a), and C_r+1Is C_rThe next point in the counterclockwise direction; coefficient M_r、M_r+1Solving by a catch-up method; h is_r=x_r+1-x_r；y_r、y_r+1Are respectively point C_r、C_r+1The ordinate of (c).

When the obstacle exists in the curved farmland operation area, acquiring the coordinate Z (x) of the vertex of the obstacle in the curved farmland operation area₀,y₀) Establishing the following function equation of the barrier warning line:

the function equation of the first-level obstacle warning line is (x-x)₀)²+(y-y₀)²=a²；

The function equation of the secondary obstacle warning line is (x-x)₀)²+(y-y₀)²=b²；

The function equation of the three-level obstacle warning line is (x-x)₀)²+(y-y₀)²=c²；

Wherein 0< a < b < c < 50.

Solving for coefficient M by catch-up method_t、M_t+1Comprises the following steps:

1) let β₁=b₁,y₁=d₁(ii) a Wherein, $b_1=2+{\mathrm{\&mu;}}_1+\frac{{\mathrm{\&mu;}}_1{h}_0}{h_1},b_2=2,...,b_{n-2}=2,$ $b_{n-1}=2+{\mathrm{\&lambda;}}_{n-1}+\frac{{\mathrm{\&lambda;}}_{n-1}{h}_{n-1}}{h_{n-2}};$ ${\mathrm{\&mu;}}_p=\frac{h_{p-1}}{h_{p-1}+h_p};$ $d_p=6\frac{f[x_p,x_{p+1}]-f[x_{p-1},x_p]}{h_{p-1}+h_p}=6\frac{\frac{y_{p+1}-y_p}{x_{p+1}-x_p}-\frac{y_p-y_{p-1}}{x_p-x_{p-1}}}{h_{p-1}+h_p};$ λ_p=1-μ_p；p=1,2,...,n-1；

2) computingβ_q=b_q-l_qc_q-1,y_q=d_q-l_qy_q-1(ii) a Wherein q =2,3, …, n-1; $a_2={\mathrm{\&mu;}}_2,$ $a_3={\mathrm{\&mu;}}_3,...,a_{n-1}={\mathrm{\&mu;}}_{n-1}-\frac{{\mathrm{\&lambda;}}_{n-1}{h}_{n-1}}{h_{n-2}};$ $c_1={\mathrm{\&lambda;}}_1-\frac{{\mathrm{\&mu;}}_1{h}_0}{h_1},c_2={\mathrm{\&lambda;}}_2,c_3={\mathrm{\&lambda;}}_3,...,c_{n-2}={\mathrm{\&lambda;}}_{n-2};$

3) solving for M using_n-1：

4) Calculate M using the following equation_n-2,M_n-3,L,M₁：s=n-2,n-3,…,1；

5) M is calculated by₀And M_n： $M_0=M_1-\frac{h_0}{h_1}(M_2-M_1),$ $M_n=M_{n-1}+\frac{h_{n-1}}{h_{n-2}}(M_{n-1}-M_{n-2}).$

Compared with the prior art, the invention has the beneficial effects that: the invention can accurately record and draw the boundary of the curved farmland operation area and the top point of the barrier in the farmland operation area, thereby providing an accurate farmland operation area for operators of the agricultural plant protection machine and providing a reliable basis for path and track planning and farmland operation area calculation of the agricultural plant protection machine.

Drawings

FIG. 1 is a schematic diagram of a curvilinear boundary model according to an embodiment of the present invention;

fig. 2 is a model of a barrier warning line of an agricultural operation area with a barrier according to an embodiment of the present invention.

Detailed Description

The following detailed description of the embodiments of the invention refers to the accompanying drawings.

1) Suppose a pick-point worker starts with the first keypoint and picks m keypoints in turn in the clockwise direction (with period T of GPS)_sAs sampling periods for collecting boundary points of the field work area), respectively D₁(x₁,y₁),D₂(x₂,y₂),D₃(x₃,_y3),…,D_m(x_m,y_m) As shown in fig. 1;

2) the abscissas of the m points are compared to find the point where the abscissa is minimum and maximum. Assuming the point with the smallest abscissaIs D_i(x_i,y_i) The point with the largest abscissa is D_j(x_j,y_j). (if the abscissa of a plurality of points is the minimum, the point with the first point order is taken as the minimum point, there is a special case that if D is the minimum value₁And D_mAre all equal, but here D is taken_mAs a minimum point; if the abscissa of a plurality of points is the maximum value, the point with the last point in the point order is taken as the maximum point, and there is a special case here: if D is_mAnd D₁Are all equal, but here D is taken₁As a maximum point), then D_i(x_i,y_i) I.e. the left end, D_j(x_j,y_j) Namely the right end;

3) suppose from the left end D_iAnd right end D_jThe determined upper bound has | j-i | +1 point, let n = | j-i | (including left end D)_iAnd right end D_j) To facilitate the following calculation, points on the upper boundary (including the left end D) are set_iAnd right end D_j) Sequentially marked as B from left to right in the clockwise direction₀(x₀,y₀),K,B_n(x_n,y_n) (Jiling D)_i=B₀,D_i+1=B₁,…,D_j=B_nIf when j is<i, in the process of shifting points in the clockwise direction, if D_nAppears at D_jLeft side of (i.e. x)_n<x_j) Let D_nThe next point of (A) is D₁If D is_n=B_k(k<n) then D₁=B_k+1,D₂=B_k+2,K,D_j=B_n。

The upper boundary function s (x) satisfies:

（1）S(x_t)=y_t(j=0,1,…,n)；

(2) s (x) in each cell [ x ]_t,x_t+1](t =0,1, …, n-1) is a 3 rd order polynomial;

(3) s (x) in [ x ]₀,x_n]There are successive 2 derivatives above;

(4) end point conditions: the third derivative of the first and second cubic polynomials is forced to be equal, and the same applies to the last and second last cubic polynomials.

According to the three bending moment equation method for solving the 3-order spline function, set S' (x)_t)=M_t，t=0,1,...,n，

Remember h_t=x_t+1-x_t,t=0,1,...,n-1。

(1) Deriving mu by arranging cubic spline function_tM_t-1+2M_t+λ_tM_t+1=d_tT =1,2,. n-1, wherein, ${\mathrm{\&mu;}}_t=\frac{h_{t-1}}{h_{t-1}+h_t},$ λ_t=1-μ_t, $d_t=6f[x_{t-1},x_t,x_{t+1}]=6\frac{f[x_t,x_{t+1}]-f[x_{t-1},x_t]}{h_{t-1}+h_t}=6\frac{\frac{y_{t+1}-y_t}{x_{t+1}-x_t}-\frac{y_t-y_{t-1}}{x_t-x_{t-1}}}{h_{t-1}+h_t}.$

(2) as is known from the end-point conditions, $\begin{array}{c}\frac{M_n-M_{n-1}}{h_{n-1}}=\frac{M_{n-1}-M_{n-2}}{h_{n-2}}\&DoubleRightArrow;{M_n=M}_{n-1}+\frac{h_{n-1}}{h_{n-2}}(M_{n-1}-M_{n-2})\\ \frac{M_{\text{1}}-M_{\text{0}}}{h_0}=\frac{M_2-M_1}{h_1}\&DoubleRightArrow;M_0=M_1-\frac{h_0}{h_1}(M_2-M_1)\end{array},$

is measured by mu_tM_t-1+2M_t+λ_tM_t+1=d_tT =1, 2.. n-1 is known as μ₁M₀+2M₁+λ₁M₂=d₁

∴ $(2+{\mathrm{\&mu;}}_1+\frac{{\mathrm{\&mu;}}_1{h}_0}{h_1})M_1+({\mathrm{\&lambda;}}_1-\frac{{\mathrm{\&mu;}}_1{h}_0}{h_1})M_2=d_1,$

Is measured by mu_tM_t-1+2M_t+λ_tM_t+1=d_tT =1, 2.. n-1 is known as μ_n-1M_n-2+2M_n-1+λ_n-1M_n=d_n-1,

∴ $({\mathrm{\&mu;}}_{n-1}-\frac{{\mathrm{\&lambda;}}_{n-1}{h}_{n-1}}{h_{n-2}})M_{n-2}+(2+{\mathrm{\&lambda;}}_{n-1}+\frac{{\mathrm{\&lambda;}}_{n-1}{h}_{n-1}}{h_{n-2}})M_{n-1}=d_{n-1}.$

(3) Combining (1) and (2) to obtain a matrix

And solving a coefficient array and a right end item of the three-bend matrix.

(4) In addition $b_1=2+{\mathrm{\&mu;}}_1+\frac{{\mathrm{\&mu;}}_1{h}_0}{h_1},b_2=2,...,b_{n-2}=2,b_{n-1}=2+{\mathrm{\&lambda;}}_{n-1}+\frac{{\mathrm{\&lambda;}}_{n-1}{h}_{n-1}}{h_{n-2}},$

$c_1={\mathrm{\&lambda;}}_1-\frac{{\mathrm{\&mu;}}_1{h}_0}{h_1},c_2={\mathrm{\&lambda;}}_2,c_3={\mathrm{\&lambda;}}_3,...,c_{n-2}={\mathrm{\&lambda;}}_{n-2},$

$a_2={\mathrm{\&mu;}}_2,a_3={\mathrm{\&mu;}}_3,...,a_{n-1}={\mathrm{\&mu;}}_{n-1}-\frac{{\mathrm{\&lambda;}}_{n-1}{h}_{n-1}}{h_{n-2}},$

The matrix in (3) becomes $\left(\begin{array}{ccccccc}{b}_1& c_1& & & & & \\ a_2& b_2& c_2& & & & \\ & a_3& b_3& c_3& & & \\ & & \&CenterDot;& \&CenterDot;& \&CenterDot;& & \\ & & & \&CenterDot;& \&CenterDot;& \&CenterDot;& \\ & & & & a_{n-2}& b_{n-2}& c_{n-2}\\ & & & & & a_{n-1}& b_{n-1}\end{array}\right)\left(\begin{array}{c}{M}_1\\ M_2\\ M_3\\ \&CenterDot;\\ \&CenterDot;\\ M_{n-2}\\ M_{n-1}\end{array}\right)=\left(\begin{array}{c}{d}_1\\ d_2\\ d_3\\ \&CenterDot;\\ \&CenterDot;\\ d_{n-2}\\ d_{n-1}\end{array}\right)$

(5) Finding M by catch-up_t,t=1,2,…,n-1。

The specific process is as follows:

①β₁=b₁,y₁=d₁；

② for i =2,3, …, n-1, calculationβ_i=b_i-l_ic_i-1,y_i=d_i-l_iy_i-1；

③ $M_{n-1}=\frac{y_{n-1}}{{\mathrm{\&beta;}}_{n-1}};$

④ for i = n-2, n-3, …,1, calculation

⑤ calculation $M_0=M_1-\frac{h_0}{h_1}(M_2-M_1),$ $M_n=M_{n-1}+\frac{h_{n-1}}{h_{n-2}}(M_{n-1}-M_{n-2});$

(6) Calculating S according to the following formula_(x)In each interval [ x_t,x_t+1]Upper expression S_t(x)Which is a $S_{t\left(x\right)}=M_t\frac{{(x_{t+1}-x)}^3}{{6h}_t}+M_{t+1}\frac{{(x-x_t)}^3}{{6h}_t}+(y_t-\frac{M_t{h}_t^2}{6})\frac{x_{t+1}-x}{h_t}+(y_{t+1}-\frac{M_{t+1}{h}_t^2}{6})\frac{{x-x}_t}{h_t}$ $(x\&Element;[x_t,x_{t+1,}],t=\mathrm{0,1},...,n-1)$

4) Lower boundary function model

Left end D_iAnd right end D_jOn the determined lower boundary there are n +1= m- | j-i | +1 points (including the left end D)_iAnd right end D_j) For later calculation, points on the lower boundary (including the left end D) are set_iAnd right end D_j) Sequentially marked as C from left to right in the anticlockwise direction₀(x₁,y₁),K,C_n(x_n,y_n) (Jiling D)_i=C₀,D_i-1=C₂,…,D_j=C_nIf when j is>i, in the process of moving point in the counterclockwise direction, if D₁Appears at D_jLeft side of (i.e. X)₁<X_j) Then order D₁The next point of (A) is D_n(ii) a If D is₁=C_k(k<n), then D)_n=C_k+1，D_n-1=C_k+2,...,D_j=C_n）。

The lower bound function computation is the same as the upper bound function computation process.

If there is an obstacle in the field, the picking-point worker picks the obstacle pointThe coordinate is Z (x)₀,y₀) Assume that the primary warning line is a circle a meters away from the obstacle point, the secondary warning line is a circle b meters away from the obstacle point, and the tertiary warning line is a circle c meters away from the obstacle point (50)>c>b>a>0) As shown in fig. 2, the three circles in fig. 2 are respectively a primary warning line, a secondary warning line and a tertiary warning line from inside to outside.

The function equation of the first-level warning line is (x-x)₀)²+(y-y₀)²=a²；

The function equation of the secondary warning line is (x-x)₀)²+(y-y₀)²=b²；

The function equation of the three-level warning line is (x-x)₀)²+(y-y₀)²=c²。

Claims (3)

1. A method for modeling the boundary of a curved farmland operation area is characterized by comprising the following steps:

1) a certain key point D from the boundary of curved farmland operation area₁Starting, collecting all key points of the boundary of the curved farmland operation area in the clockwise direction, and setting a total of m key points as D₁(x₁,y₁),D₂(x₂,y₂),D₃(x₃,y₃),…,D_m(x_m,y_m) (ii) a Establishing a rectangular coordinate system, and setting the m key pointsThe device is arranged in a first quadrant of a rectangular coordinate system;

2) comparing the abscissa of the m key points to find out the key point with the maximum abscissa value and the key point with the minimum abscissa value; if the abscissa values of the plurality of key points are all the minimum values, and the plurality of key points are the first key point D₁And the last key point D_mThe key point with the first order is used as the key point with the minimum abscissa value if the key point D is the first key point₁And the last keypoint D_mIf the abscissa values are all the minimum values, the last key point is taken as the key point with the minimum abscissa value; if the abscissa values of the plurality of key points are all the maximum values, and the plurality of key points are the first key point D₁And the last key point D_mThe key point with the last order is taken as the key point with the maximum abscissa value, if the first key point D₁And the last keypoint D_mIf the abscissa values of the first and second points are all maximum values, the first key point D is determined₁As the key point with the maximum horizontal coordinate value; key point D with smallest horizontal coordinate value_iAnd the largest key point D_jRespectively serving as the left end and the right end of all key points in a rectangular coordinate system; if the abscissa values of a plurality of key points are all minimum values, one key point is a first key point or a last key point, and the other key points are key points between the first key point and the last key point, taking a point with the first order in a closed interval from the first key point to the last key point as a minimum point; if the abscissa values of a plurality of key points are the maximum values, one key point is a first key point or a last key point, and the other key points are key points between the first key point and the last key point, taking a point with the last order in a closed interval from the first key point to the last key point as a maximum point;

3) with D_iAs a starting point, D_jIs the end point; in the clockwise direction, order D_i＝B₀,D_i+1＝B₁,…,D_j＝B_nWill be driven from D_iTo D_jEach point in turn is B₀(x₀,y₀),...,B_n(x_n,y_n) (ii) a Establishing the following upper boundary function model S_t(x)：

$S_{t\left(x\right)}=M_t\frac{{(x_{t+1}-x)}^3}{6h_t}+M_{t+1}\frac{{(x-x_t)}^3}{6h_t}+(y_t-\frac{M_t{h_t}^2}{6})\frac{x_{t+1}-x}{h_t}+(y_{t+1}-\frac{M_{t+1}{h_t}^2}{6})\frac{x-x_t}{h_t};$

Wherein, x ∈ [ x_t,x_t+1,],t＝0,1,...,n-1；x_t、x_t+1Are respectively B₀、B_nPoint B in between_t、B_t+1On the abscissa of (a) and B_t+1Is B_tThe next point in the clockwise direction; coefficient M_t、M_t+1Solving by a catch-up method;

h_t＝x_t+1-x_t,t＝0,1,...,n-1；y_t、y_t+1are respectively point B_t、B_t+1The ordinate of (a);

4) with D_iAs a starting point, D_jIs the end point; in the counterclockwise direction, let D_i＝C₀,D_i-1＝C₁,…,D_j＝C_rEstablishing the following upper boundary function model S_r(x)：

$S_{r\left(x\right)}=M_r\frac{{(x_{r+1}-x)}^3}{6h_r}+M_{r+1}\frac{{(x-x_r)}^3}{6h_r}+(y_r-\frac{M_r{h_r}^2}{6})\frac{x_{r+1}-x}{h_r}+(y_{r+1}-\frac{M_{r+1}{h_r}^2}{6})\frac{x-x_r}{h_r};$

Wherein, x ∈ [ x_r,x_r+1,],r＝0,1,...,m-n；x_r、x_r+1Are respectively C₀、C_m-nPoint C in between_r、C_r+1On the abscissa of (a), and C_r+1Is C_rThe next point in the counterclockwise direction; coefficient M_r、M_r+1Solving by a catch-up method; h is_r＝x_r+1-x_r；y_r、y_r+1Are respectively point C_r、C_r+1The ordinate of (c).

2. The method of modeling the boundary of a curved farmland operation area according to claim 1, wherein when an obstacle exists in the curved farmland operation area, the coordinates Z (x) of the apex of the obstacle in the curved farmland operation area are collected₀,y₀) Establishing the following function equation of the barrier warning line:

the function equation of the first-level obstacle warning line is (x-x)₀)²+(y-y₀)²＝a²；

The function equation of the secondary obstacle warning line is (x-x)₀)²+(y-y₀)²＝b²；

Three-level barrier warningThe functional equation of the line is (x-x)₀)²+(y-y₀)²＝c²；

Wherein a is more than 0 and less than b and less than c and less than 50.

3. The method for modeling the boundary of a curved farmland working area according to claim 1 or 2, wherein the coefficient M is solved by a catch-up method_t、M_t+1Comprises the following steps:

1) let β₁＝b₁,y₁＝d₁(ii) a Wherein,b₂＝2，...，b_n-2＝2， λ_p＝1-μ_p；p＝1，2，...，n-1；

2) computingβ_q＝b_q-l_qc_q-1,y_q＝d_q-l_qy_q-1(ii) a Wherein q is 2,3, …, n-1; a is₂＝μ₂，c₂＝λ₂，c₃＝λ₃，...，c_n-2＝λ_n-2；

3) Solving for M using_n-1：

4) Calculate M using the following equation_n-2,M_n-3,…,M₁：s＝n-2，n-3，...，1；

5) M is calculated by₀And M_n： $M_n=M_{n-1}+\frac{h_{n-1}}{h_{n-2}}(M_{n-1}-M_{n-2}).$