阅读说明：本技术 一种农机覆盖路径规划方法 (Agricultural machinery coverage path planning method ) 是由 董笑辰 陶斯友 张强 于 2021-08-30 设计创作，主要内容包括：本发明公开了一种农机覆盖路径规划方法,包括如下步骤：S1：确定路径规划的初始参数；S2：将所述原始田块边界点集P向所述田块边界内部平移距离L,以确定农机工作区域的边界；S3：建立x-y轴直角坐标系,计算所述农机工作区域的最小跨度；S4：生成所述农机工作区域旋转最优旋转角度时的平行路径；S5：生成农机的转弯路径,并将农机的转弯路径与直线路径连接,以构成农机工作完整的路径。通过优化平行路径角度的方法,减少了农机转弯次数,提高农机的工作效率,由于是将田块旋转后,通过计算每条边界的倾斜角计算最优平行路径的角度的方法,避免通过角度递增的迭代方法,同时用平行于x轴的扫描线生成平行路径,简化计算工作量。(The invention discloses an agricultural machinery coverage path planning method, which comprises the following steps: s1: determining initial parameters of path planning; s2: translating the original field block boundary point set P to the interior of the field block boundary by a distance L so as to determine the boundary of the agricultural machinery working area; s3: establishing an x-y axis rectangular coordinate system, and calculating the minimum span of the working area of the agricultural machine; s4: generating a parallel path when the working area of the agricultural machine rotates by the optimal rotation angle; s5: and generating a turning path of the agricultural machine, and connecting the turning path of the agricultural machine with a straight path to form a path for the agricultural machine to work completely. The method for optimizing the angle of the parallel path reduces the turning times of the agricultural machine and improves the working efficiency of the agricultural machine, and because the method is a method for calculating the angle of the optimal parallel path by calculating the inclination angle of each boundary after the field is rotated, the iterative method of increasing the angle is avoided, and meanwhile, the parallel path is generated by using the scanning line parallel to the x axis, and the calculation workload is simplified.)

1. An agricultural machinery coverage path planning method is characterized by comprising the following steps:

s1: determining initial parameters of path planning, wherein the initial parameters comprise an original field boundary point set P, the width w of each line scanning of the agricultural machine and the minimum turning radius of the agricultural machine;

s2: translating the original field block boundary point set P to the interior of the field block boundary by a distance L so as to determine the boundary of the agricultural machinery working area;

s3: establishing an x-y axis rectangular coordinate system, and calculating the minimum span of the working area of the agricultural machine to determine the optimal rotation angle of the original field;

s4: generating a parallel path when the working area of the agricultural machine rotates by the optimal rotation angle so as to determine a straight path of the agricultural machine;

s5: and generating a turning path of the agricultural machine, and connecting the turning path of the agricultural machine with a straight path to form a path for the agricultural machine to work completely.

2. The agricultural machine coverage path planning method according to claim 1, wherein in the step S3, the method for calculating the minimum span of the agricultural machine working area is as follows:

when the boundary of the working area of the agricultural machine is a convex polygon, the turning times n of the agricultural machine are as follows:

d is the span of the boundary of the working area of the agricultural machine in the direction perpendicular to the scanning line, and the scanning line is a straight line parallel to the x axis in the x-y axis rectangular coordinate system;

y＝y_min，x∈[x_min，x_max] (2)

wherein, y_minIs the minimum value of the boundary of the working area of the agricultural machine on the y axis; x is the number of_minIs the minimum value of the boundary of the working area of the agricultural machine on the x axis; x is the number of_maxIs the maximum value of the boundary of the working area of the agricultural machine on the x axis; d ═ y_max-y_min；

The rotation angle of each time of the original field piece is as follows:

wherein [ x ]₁，y₁]Is the starting point coordinate of the side parallel to the x axis in the boundary of the working area of the agricultural machine; [ x ] of₂，y₂]Is the end point coordinate of the side parallel to the x-axis in the boundary of the working area of the agricultural machine, theta_tIs a rotation angle, and after the rotation is carried out for multiple times, the rotation angle when the span D is minimum is the optimal rotation angle theta of the working area of the agricultural machine^*；

When the agricultural machinery working area is a concave polygon, firstly calculating a convex hull based on boundary points of the agricultural machinery working area, and then calculating the optimal rotation angle theta of the field block^*。

3. The agricultural machine coverage path planning method according to claim 2, wherein in the step S4, the method for determining the straight path of the agricultural machine is as follows:

s41: clockwise rotating the original field block by the optimal rotation angle theta by taking the mass center of the convex polygon as the rotation center^*Obtaining a boundary P' of the agricultural machinery working area with the minimum span;

s42: successively scanning the scanning lines by y_minTo y_maxDirection translation, each time translation w; calculating the number of intersection points of the scanning lines and the boundary P' of the agricultural machinery working area after each translation; wherein, y_maxIs the maximum value of the boundary of the working area of the agricultural machine on the y axis;

s43: if the number of the intersection points is 2, the coordinates of the two intersection points are considered to be still in the boundary of the working area of the agricultural machine, and scanning is continued; if the number of the intersection points is 1 or 0, judging that the intersection points exceed the boundary range of the agricultural machinery working area, stopping scanning, and completing the generation process of the parallel path.

4. The agricultural machine coverage path planning method according to claim 1, wherein the turning path includes three types: pi-type, fishtail type, and semi-circular type;

when the turning path is in a fishtail shape, w is less than 2 r;

when the turning path is semicircular, w is 2 r;

when the turning path is pi-shaped, w is more than 2 r.

5. The agricultural machine coverage path planning method according to claim 1, wherein the manner of generating the turning path of the agricultural machine in the S5 includes a first turning path generation manner and a second turning path generation manner:

if the first line segment is known, generating an arc tangent to the first line segment by combining the turning radius, the turning direction and the turning angle; at the moment, a first turning path generation mode is adopted;

if the first line segment and the second line segment are known, generating an arc tangent to both the first line segment and the second line segment by combining the turning radius, and adopting a second turning path generation mode at the moment.

6. The agricultural machine coverage path planning method according to claim 5, wherein the first turning path generation manner comprises the following steps:

s511: determining the circle center coordinate of the turning path;

in the formula [ x_c，y_c]Is the center coordinate, [ x ]₂，y₂]Is the coordinate of the tangent point, clockwise means clockwise rotation, unclockwise means counterclockwise rotation, [ theta ] theta₁Is the angle of inclination of the first line segment; alpha is the included angle between the connecting line of the tangent point of the turning path and the first line segment and the circle center and the positive direction of the x axis;

s512: determining a range of a turning path;

by beta₁Angle of inclination, beta, representing the line connecting the origin (point of tangency) and the centre of the circle₂The inclination angle of the connecting line of the end point and the circle center is shown,

in the formula, beta₁The included angle beta between the connecting line of the starting point (tangent point) of the turning radius and the circle center and the positive direction of the X axis₂The included angle between the connecting line of the end point of the turning radius and the circle center and the positive direction of the X axis is shown,is the central angle of the turning path;

s513: generating a turning path;

in the formula: [ x ] of_i，y_i]Is the i-th discrete point from the start of the turning path, and Δ s is the arc length between two discrete points on the arc.

7. The agricultural machine coverage path planning method according to claim 5, wherein the second turning path generation manner comprises the following steps:

s521: determining a rotation direction of the turning path;

in the formula: [ x ] of₃，y₃]Coordinates of a starting point of the second line segment; [ x ] of₄，y₄]Is the coordinates of the end point of the second line segment,is a direction vector formed by the starting point and the end point of the first line segment,is a direction vector formed by the starting point and the end point of the second line segment, C is the cross product of the two vectors, and orientation is the arc rotation direction;

s522: calculating the tangent point of the first line segment;

in the formula: theta_vIs a vectorAndangle between them, [ x ]_t，y_t]Is the coordinate of the tangent point of the first line segment, [ x ]₀，y₀]Is the coordinate of the intersection of the first line segment and the second line segment, and ω is an intermediate variable representing the direction; theta₁Is the included angle between the first line segment and the positive direction of the x axis;

s523: determining the central angle of the turning path:

in the formula:is the central angle of the turning path.

Technical Field

The invention relates to the technical field of agricultural machinery operation control, in particular to a method for planning a coverage path of an agricultural machinery.

Background

In recent years, the automatic driving technology is rapidly developed, and the automatic driving technology is very suitable for the application of the automatic driving technology in the current stage due to the characteristics of simple working environment and single operation mode of agricultural machinery. In the automatic driving key technology, global path planning is the basis for ensuring the safety and high efficiency of vehicles to complete the driving target. Researchers have designed many path planning methods for passenger vehicles, but there is little research on global path planning algorithms for agricultural machinery. The existing method does not consider the working characteristics of agricultural machinery and is not suitable for automatically-driven agricultural machinery equipment. Considering the working target and the working mode of the agricultural machine, the coverage path planning algorithm for the sweeping robot is closer to the working mode of the agricultural machine. Different from the path planning of agricultural machinery, the sweeping robot can realize the steering at any angle in situ, and the agricultural machinery is controlled by the steering mechanism and must steer according to a certain turning radius.

Disclosure of Invention

The invention provides an agricultural machinery coverage path planning method, which aims at automatically driving agricultural machinery, solves the problems existing in the agricultural machinery global path planning, provides a method for determining the working range of the agricultural machinery, determining the detour mode, planning the parallel path and the turning path according to an input point, and provides a global path planning method considering the working characteristics and the coverage path planning algorithm.

In order to achieve the purpose, the technical scheme of the invention is as follows: an agricultural machinery coverage path planning method comprises the following steps:

s1: determining initial parameters of path planning, wherein the initial parameters comprise an original field boundary point set P, the width w of each line scanning of the agricultural machine and the minimum turning radius of the agricultural machine;

s2: translating the original field block boundary point set P to the interior of the field block boundary by a distance L so as to determine the boundary of the agricultural machinery working area;

s3: establishing an x-y axis rectangular coordinate system, and calculating the minimum span of the working area of the agricultural machine to determine the optimal rotation angle of the original field;

s4: generating a parallel path when the working area of the agricultural machine rotates by the optimal rotation angle so as to determine a straight path of the agricultural machine;

s5: and generating a turning path of the agricultural machine, and connecting the turning path of the agricultural machine with a straight path to form a path for the agricultural machine to work completely.

Further, in S3, the method for calculating the minimum span of the working area of the agricultural machine is as follows:

when the boundary of the working area of the agricultural machine is a convex polygon, the turning times n of the agricultural machine are as follows:

d is the span of the boundary of the working area of the agricultural machine in the direction perpendicular to the scanning line, and the scanning line is a straight line parallel to the x axis in the x-y axis rectangular coordinate system;

y＝y_min,x∈[x_min,x_max] (2)

wherein, y_minIs the minimum value of the boundary of the working area of the agricultural machine on the y axis; y is_maxIs the maximum value of the boundary of the working area of the agricultural machine on the y axis; x is the number of_minIs the minimum value of the boundary of the working area of the agricultural machine on the x axis; x is the number of_maxIs the maximum value of the boundary of the working area of the agricultural machine on the x axis; d ═ y_max-y_min；

The rotation angle of each time of the original field piece is as follows:

wherein [ x ]₁,y₁]Is the starting point coordinate of the side parallel to the x axis in the boundary of the working area of the agricultural machine; [ x ] of₂,y₂]Is the end point coordinate of the side parallel to the x-axis in the boundary of the working area of the agricultural machine, theta_tIs a rotation angle, and after the rotation is carried out for multiple times, the rotation angle when the span D is minimum is the optimal rotation angle theta of the working area of the agricultural machine^*；

When the agricultural machinery working area is a concave polygon, firstly calculating boundary points based on the agricultural machinery working areaConvex hull, then calculating the optimal rotation angle theta of the field block^*。

Further, in S4, the method for determining the straight path of the agricultural machine includes:

s41: clockwise rotating the original field block by the optimal rotation angle theta by taking the mass center of the convex polygon as the rotation center^*Obtaining a boundary P' of the agricultural machinery working area with the minimum span;

s42: gradually translating the scanning line to the positive direction of the y axis, and translating w each time; calculating the number of intersection points of the scanning lines and the boundary P' of the agricultural machinery working area after each translation;

s43: if the number of the intersection points is 2, the coordinates of the two intersection points are considered to be still in the boundary of the working area of the agricultural machine, and scanning is continued; if the number of the intersection points is 1 or 0, judging that the intersection points exceed the boundary range of the agricultural machinery working area, stopping scanning, and completing the generation process of the parallel path.

Further, the turning path includes three types: pi-type, fishtail type, and semi-circular type;

when the turning path is fishtail, w <2 r;

when the turning path is semicircular, w is 2 r;

when the turning path is pi-shaped, w >2 r.

Further, the manner of generating the turning path of the agricultural machine in S5 includes a first turning path generation manner and a second turning path generation manner:

if the first line segment is known, generating an arc tangent to the first line segment by combining the turning radius, the turning direction and the turning angle; at the moment, a first turning path generation mode is adopted;

if the first line segment and the second line segment are known, generating an arc tangent to both the first line segment and the second line segment by combining the turning radius, and adopting a second turning path generation mode at the moment.

Further, the first turning path generation method includes the steps of:

s511: determining the circle center coordinate of the turning path;

in the formula [ x_c,y_c]Is the center coordinate, [ x ]₂,y₂]Is the coordinate of the tangent point, clockwise means clockwise rotation, unclockwise means counterclockwise rotation, [ theta ] theta₁Is the angle of inclination of the first line segment; alpha is the included angle between the connecting line of the tangent point of the turning path and the first line segment and the circle center and the positive direction of the x axis;

s512: determining a range of a turning path;

by beta₁Angle of inclination, beta, representing the line connecting the origin (point of tangency) and the centre of the circle₂The inclination angle of the connecting line of the end point and the circle center is shown,

in the formula, beta₁The included angle beta between the connecting line of the starting point (tangent point) of the turning radius and the circle center and the positive direction of the X axis₂The included angle between the connecting line of the end point of the turning radius and the circle center and the positive direction of the X axis is shown,is the central angle of the turning path;

s513: generating a turning path;

in the formula: [ x ] of_i,y_i]Is the i-th discrete point from the start of the turning path, and Δ s is the arc length between two discrete points on the arc.

Further, the second turning path generation method includes the steps of:

s521: determining a rotation direction of the turning path;

in the formula: [ x ] of₃,y₃]Coordinates of a starting point of the second line segment; [ x ] of₄,y₄]Is the coordinates of the end point of the second line segment,is a direction vector formed by the starting point and the end point of the first line segment,is a direction vector formed by the starting point and the end point of the second line segment, C is the cross product of the two vectors, and orientation is the arc rotation direction;

s522: calculating the tangent point of the first line segment;

in the formula: theta_vIs a vectorAndangle between them, [ x ]_t,y_t]Is the coordinate of the tangent point of the first line segment, [ x ]₀,y₀]Is the coordinate of the intersection of the first line segment and the second line segment, and ω is an intermediate variable representing the direction; theta₁Is the included angle between the first line segment and the positive direction of the x axis;

s523: determining the central angle of the turning path:

in the formula:is the central angle of the turning path.

Has the advantages that: according to the agricultural machinery coverage path planning method disclosed by the invention, the number of times of turning of the agricultural machinery is reduced and the working efficiency of the agricultural machinery is improved by optimizing the angle of the parallel path.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic diagram of planning parallel paths according to the present invention;

FIG. 2a is a schematic view of a fishtail-type turning path of the present invention;

FIG. 2b is a schematic view of a semicircular turn path of the present invention;

FIG. 2c is a schematic view of a pi-turn path according to the present invention;

FIG. 3 is a schematic diagram of a first type of turning path for generating a turning path according to the present invention;

FIG. 4 is a schematic diagram of a second type of turning path for generating a turning path according to the present invention;

fig. 5 is a schematic diagram of fishtail type turning path planning of the present invention.

Wherein: 1. a convex hull; 2. an agricultural work area boundary; 3. scanning a line; 4. a transition straight path; 5. a parallel path 2; 6. a parallel path 1; 7. a circular arc path 1; 8. a circular arc path 2; 9. an agricultural work area boundary; 10. a path planning region boundary.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment provides an agricultural machinery coverage path planning method, which comprises the following steps:

s1: determining initial parameters of path planning, wherein the initial parameters comprise an original field boundary point set P, the width w of each line scanning of the agricultural machine and the minimum turning radius of the agricultural machine;

specifically, the field block boundary point set P represents the boundary of the field block to be planned, and for convenience of description and calculation, elements in the point set P are all sorted according to a reverse clock; according to the working characteristics of the agricultural machine, the working path of the agricultural machine is generally scanned line by line, and all areas are covered as much as possible, so that the width (namely the line spacing required by the operation) w of each line scanning of the agricultural machine is determined, and as the turning capacity of the agricultural machine is limited by the hardware structure of a steering mechanism, the minimum turning radius r of the agricultural machine is determined in order to ensure that the agricultural machine can accurately follow the planned path;

s2: translating the original field boundary point set P to the inside of the field boundary by a distance L to determine the boundary of an agricultural machine working area and avoid the agricultural machine coverage area from exceeding the field boundary, wherein L is half of the width of the agricultural machine;

s3: establishing an x-y axis rectangular coordinate system, and calculating the minimum span of the working area of the agricultural machine to determine the optimal rotation angle of the original field; defining a coordinate axis parallel to the boundary of the span of the working area of the agricultural machine after the original field block rotates as an x axis;

specifically, because the agricultural machinery turns slowly, turning radius is great and need stop many times at least when turning, consequently turns and needs longer time. In order to reduce the total working time and improve the working efficiency, the number of turns should be reduced as much as possible when planning the path.

The method for calculating the minimum span of the working area of the agricultural machinery in the step S3 is as follows:

when the boundary of the working area of the agricultural machine is a convex polygon, the turning times n of the agricultural machine are as follows:

where D is the span of the boundary of the agricultural work area in a direction perpendicular to the scan line, which is a straight line parallel to the x-axis in the x-y orthogonal coordinate system: as shown in fig. 1; in order to simplify the description and the calculations in the present invention,

y＝y_min,x∈[x_min,x_max] (2)

wherein, y_minIs the minimum value of the boundary of the working area of the agricultural machine on the y axis; y is_maxIs the maximum value of the boundary of the working area of the agricultural machine on the y axis; x is the number of_minIs the minimum value of the boundary of the working area of the agricultural machine on the x axis; x is the number of_maxIs the maximum value of the boundary of the working area of the agricultural machine on the x axis; d ═ y_max-y_minTherefore, the number of turns is reduced, i.e., D is reduced; since the smallest span on any convex polygon always occurs in the 'point-edge' manner, i.e., the distance from a vertex to an edge that does not contain the vertex; and (3) rotating the convex polygon clockwise one by taking the mass center of the convex polygon as a rotation center to enable one side of the polygon to be parallel to the x axis, and calculating the span D. The rotation angle at each time is as follows:

wherein [ x ]₁,y₁]Is the starting point coordinate of the side parallel to the x axis in the boundary of the working area of the agricultural machine; [ x ] of₂,y₂]Is the end point coordinate of the side parallel to the x-axis in the boundary of the working area of the agricultural machine, theta_tIs the angle of rotationDegree, i.e. the angle of inclination of the side parallel to the x-axis after said rotation; the rotation angle starts from the minimum angle and stops until the rotation angle is larger than or equal to 180 degrees, and then after multiple rotations, the rotation angle when the span D is minimum is the optimal rotation angle theta of the agricultural machinery working area^*；

When the agricultural machinery working area is a concave polygon, because the calculated span of concave points and edges on the concave polygon can not cover the whole area, for the concave polygon, the invention firstly uses a mature Graham scanning method to calculate a convex hull based on boundary points of the agricultural machinery working area (namely, a convex polygon which is composed of partial vertexes in a field boundary vertex P and contains all areas of the field), and then calculates the optimal rotation angle theta of the field according to the steps^*；

S4: generating a parallel path when the working area of the agricultural machine rotates by the optimal rotation angle so as to determine a straight path of the agricultural machine; the method for determining the straight path of the agricultural machine comprises the following steps:

s41: clockwise rotating the original field block by the optimal rotation angle theta by taking the mass center of the convex polygon as the rotation center^*Obtaining a boundary P' of the agricultural machinery working area with the minimum span;

s42: gradually translating the scanning line to the positive direction of the y axis, and translating w each time; calculating the number of intersection points of the scanning lines and the boundary P' of the agricultural machinery working area after each translation;

s43: if the number of the intersection points is 2, the coordinate of each intersection point is considered to be still in the boundary of the working area of the agricultural machine, and scanning is continued; if the number of the intersection points is 1 or 0, judging that the intersection points exceed the boundary range of the agricultural machinery working area, stopping scanning, and finishing the generation of the parallel path.

S5: generating a turning path of the agricultural machine, and connecting the turning path of the agricultural machine with a straight path to form a path for the agricultural machine to work completely;

specifically, according to the relationship between the line spacing w and the turning radius r, the turning path includes three types: pi-type, fishtail type, and semi-circular type, as shown in FIG. 2;

when the turning path is fishtail, w <2 r;

when the turning path is semicircular, w is 2 r;

when the turning path is pi-shaped, w is greater than 2 r;

because the running speed of the agricultural machinery is slow, the turning process is approximately considered to be along an arc with a fixed radius; therefore, the three turning paths are all tangent connection of straight lines and fixed-curvature arcs; the generation modes can be divided into two modes according to the arc generation conditions, namely a first turning path generation mode and a second turning path generation mode:

if the first line segment is known, generating an arc tangent to the first line segment by combining the turning radius, the turning direction and the turning angle; at the moment, a first turning path generation mode is adopted;

if the first line segment and the second line segment are known, generating an arc tangent to the first line segment and the second line segment by combining the turning radius, wherein a second turning path generation mode is adopted;

the second turning path generation mode and the first turning path generation mode have the same generation process and mode of the first line segment (and tangent point), turning radius, turning direction and subsequent curve path.

When the turning path is semicircular, a first turning path generation mode is selected to avoid that the vehicle exceeds the boundary of the working area of the agricultural machinery, and the starting point of the turning path is a distance point of translating the terminal point of the first line segment in the forward direction by r; the central angle theta corresponding to the semicircular turning path is 180 degrees;

when the turning path is of a fishtail type or a pi type, firstly two parallel paths to be connected and intersection points of the two parallel paths and the boundary of the agricultural machine working area are determined, a connecting line of the two intersection points, namely a transition straight line, is translated into the boundary of the agricultural machine working area by w/2 to obtain a straight path in the turning process, and then an arc path 1 between the parallel path 1 (namely a first line segment) and the transition straight path and an arc path 2 between the transition straight path and the parallel path 2 (namely a second line segment) are generated. When the turning path is pi-shaped, the transition straight path in the turning path needs the agricultural machinery to go straight ahead, and when the turning path is fishtail-shaped, the transition straight path in the turning path needs the agricultural machinery to go straight ahead (i.e. reverse to pass) backwards, as shown in fig. 5.

The first turning path generation method includes the steps of: as shown in fig. 3:

the constraint condition of generating the circular arc by the first turning path generation mode is that the generated circular arc is tangent to a first line segment, and the tangent point is the end point of the first line segment;

s511: determining the circle center coordinate of the turning path;

in the formula [ x_c,y_c]Is the center coordinate, [ x ]₂,y₂]Is the coordinate of the tangent point, clockwise means clockwise rotation, unclockwise means counterclockwise rotation, [ theta ] theta₁The angle of inclination of a first line segment which is a known straight line;

s512: determining a range of a turning path;

the turning path range is determined by the angle between the starting point and the end point of the turning arc and the connecting line of the circle center and is determined by beta₁The included angle beta between the connecting line of the starting point (tangent point) of the turning radius and the circle center and the positive direction of the X axis₂The included angle between the connecting line of the end point of the turning radius and the circle center and the positive direction of the X axis is shown,is the central angle of the turning path;

s513: generating a turning path;

the path in the present invention is represented by ordered discrete points, so the generated circular arc path can be represented as:

in the formula: [ x ] of_i,y_i]Is the i-th discrete point from the starting point (tangent point) of the turning radius, and Δ s is the arc length between two discrete points on the arc.

The second turning path generation method includes the steps of: as shown in fig. 4;

the constraint condition for generating the circular arc by the second turning path generation mode is that the generated circular arc is tangent to the first line segment and the second line segment respectively, and the rotation direction of the circular arc is determined according to the geometric relationship of the first line segment and the second line segment.

S521: determining the direction of rotation of the turning path: the generated turning path is transited from a first line segment to a second line segment, so that the rotation direction can be determined according to the cross product between two vectors formed by the two line segments;

in the formula: [ x ] of₃,y₃]Coordinates of a starting point of the second line segment; [ x ] of₄,y₄]Is the coordinates of the end point of the second line segment,is a direction vector formed by the starting point and the end point of the first line segment,is a direction vector formed by the starting point and the end point of the second line segment, C is the cross product of the two vectors, and orientation is the arc rotation direction;

s522: calculating the tangent point of the first line segment;

the tangent point of the first line segment in the second turning path generation mode is equivalent to the end point of the first line segment in the first turning path generation mode and is the starting point of the turning radius; the tangent point of the first line segment is obtained by calculating the intersection point and the included angle of the two straight lines, and the specific calculation method is as follows:

in the formula: theta_vIs a vectorAndangle between them, [ x ]_t,y_t]Is the coordinate of the tangent point of the first line segment, [ x ]₀,y₀]Is the coordinate of the intersection of the first line segment and the second line segment, and ω is an intermediate variable representing the direction; theta₁Is the included angle between the first line segment and the positive direction of the x axis;

s523: determining the central angle of the turning path:

the central angle and the vector can be known according to the geometrical relationAndthe included angles are complementary, and the central angles are as follows:

in the formula:is the central angle of the turning path.

The invention has the following beneficial effects:

1: for a field with a concave outer boundary, the invention determines the convex boundary surrounding the field by a Graham scanning method so as to determine the angle of the optimal parallel path.

2: the invention provides a method for optimizing the angle of the parallel path, which reduces the turning times of the agricultural machine and can improve the working efficiency of the agricultural machine. And after the field is rotated, parallel paths are generated by using scanning lines parallel to the x axis, so that the calculation can be simplified.

3: the invention provides a method for calculating the angle of the optimal parallel path only by calculating the inclination angle of each boundary, thereby avoiding the iteration method of increasing the angle and reducing the calculation amount.

4: the invention provides three different turning paths through the relation between the turning radius and the line spacing of the agricultural machine, and ensures that the agricultural machine can smoothly run along the planned path.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.