A general modeling method for peanut plant based on discrete element method

Abstract

A peanut plant general modeling method based on a discrete element method, the present application solves the problem that the modeling of peanut plants is mostly particle aggregation, which can describe the detailed morphology, but requires a large number of particles to maintain geometric continuity and mechanical response, resulting in a large calculation scale, slow speed and difficult parameter calibration in the simulation process. The present application determines the type and arrangement of the ball particles of the geometric model of the peanut plant according to the geometric shape and characteristic size of each part of the peanut plant, and obtains the coordinates of the ball particles of each part of the peanut plant. The geometric model of the peanut plant is established according to the coordinates, the contact mechanics parameters and the bonding mechanics parameters of each part of the peanut plant are measured and calibrated, the contact mechanics parameters and the bonding mechanics parameters are added to the mechanical model, and the geometric model and the added mechanical model of the peanut plant are input into the discrete element software to obtain the peanut plant model. The present application belongs to the technical field of plant modeling analysis.

Description

Technical Field

[0001] This invention relates to the field of plant modeling and analysis technology, specifically to a general modeling method for peanut plants based on the discrete element method. Background Technology

[0002] As an important oilseed and cash crop, peanuts have seen continuous growth in overall yield and output per unit area in recent years due to optimized planting structure, large-scale production, and improved management. Peanut harvesting mainly employs a segmented harvesting method, which can be simply described as follows: the first stage is peanut lifting, and the second stage is peanut collection. During the first stage of peanut lifting, the peanut plant, being a complex plant with "earthly seeds and abundant above-ground growth," has a complex and intertwined stem and root system, numerous branches, and a fragile connection between the pegs and pods, all of which pose significant challenges to the lifting operation. Especially in the interaction with the soil and harvesting machinery, damage, detachment, and fruit breakage frequently occur, severely affecting the harvesting efficiency and quality. Currently, the peanut lifting process still mainly relies on physical experiments and field trials for machinery optimization. This method is not only time-consuming and costly, but also susceptible to multiple factors such as environment, soil moisture, and mechanical performance, making it difficult to meet the needs of efficient, precise, and intelligent development of peanut harvesting machinery.

[0003] The Discrete Element Method (DEM) provides an effective numerical simulation tool for studying the operational mechanism of segmented peanut harvesting. It can explicitly characterize and calculate nonlinear processes such as multi-body contact, friction, separation, and (adhesion-induced) fracture among the plant, soil, and machinery, thereby reproducing the impact of different working conditions on operational quality in a virtual environment. However, to date, there is a lack of published and structurally sound peanut plant DEM modeling methods. Existing publicly available plant modeling methods mostly adopt the general approach of particle aggregation (multi-sphere filling), which, while capable of describing detailed morphology, often requires a large number of particles to maintain geometric continuity and mechanical response, resulting in excessively large computational scale, slow speed, and difficulties in parameter calibration during simulation. Therefore, there is an urgent need to research a peanut plant modeling method based on the Discrete Element Method that balances modeling efficiency and simulation stability while ensuring reasonable hierarchical and connection relationships among different parts of the peanut plant. This method can be used to explore the stress and deformation mechanisms during the peanut harvesting stage and efficiently evaluate the contact-interaction between different parts of the peanut plant and key components of agricultural machinery. Summary of the Invention

[0004] To address the problem that existing peanut plant modeling methods often employ particle aggregation, which can describe detailed morphology but requires a large number of particles to maintain geometric continuity and mechanical response, resulting in excessively large computational scale, slow speed, and difficulty in parameter calibration during simulation, this invention proposes a general peanut plant modeling method based on the discrete element method.

[0005] The technical solution adopted in this invention is:

[0006] It includes the following steps:

[0007] S1. Analyze the geometric morphology and characteristic dimensions of various parts of the peanut plant;

[0008] S2. Based on S1, determine the type and arrangement of the spherical particles that make up the geometric model of the peanut plant;

[0009] S3. Based on the arrangement in S2, calculate the coordinates of the spherical particles that make up each part of the peanut plant;

[0010] S4. Establish a geometric model of the peanut plant based on the coordinates of the spherical particles that make up different parts of the peanut plant.

[0011] S5. Based on the geometric model of the peanut plant, measure and calibrate the contact mechanical parameters and adhesive mechanical parameters of various parts of the peanut plant.

[0012] S6. Add the contact mechanical parameters and adhesion mechanical parameters of each part of the peanut plant to the mechanical model to obtain the added mechanical model;

[0013] S7. Input the geometric model of the peanut plant and the added mechanical model into the discrete element method software to obtain the peanut plant model.

[0014] The beneficial effects of this invention are as follows:

[0015] Based on extensive measurement and statistical analysis, this invention proposes key characteristic dimensional parameters and their interrelationships required for peanut plant modeling (such as parameters for the main stem / main root conical transition segment, parameters for the first branching and peg, and parameters for the lateral root outward curve). This provides crucial data support for the feasibility and accuracy of peanut plant modeling. This invention employs a "main stem / main root segmented conical transition (rapid conical transition segment + gradual conical transition segment) + first branching / peg / lateral root tangential angle" approach. The combined modeling of "cubic function variation" significantly reduces the number of required particles and contacts while maintaining geometric accuracy and mechanical continuity, making parameter calibration much simpler than before. This reduces the computational scale of discrete element method, shortens simulation time, and improves simulation speed.

[0016] This invention drives the geometric and mechanical modeling of peanut plants through adjustable parameters (length, radius, unfolding angle of the connecting end, and tangential angle of the non-connecting end), which can quickly adapt to different varieties, cultivation conditions, and ripening / drying stages. It can accurately represent the contact-friction-separation / fracture characteristics of peanut plants during mechanical operations such as harvesting / picking, and provide more accurate data support for the evaluation of the interaction between peanut plants and key components of harvesters and parameter optimization. Attached Figure Description

[0017] Figure 1 This is a picture of a peanut plant.

[0018] Figure 2 This is a schematic diagram of a peanut plant model;

[0019] Figure 3 A schematic diagram of the various parts of a peanut plant.

[0020] Figure 4 A schematic diagram of the main stem, taproot, and first branching cone segment;

[0021] Figure 5 A schematic diagram defining the angles of the first branching, fruit pegs, and lateral roots;

[0022] Figure 6 This is the main view of the first branch distribution at each level;

[0023] Figure 7 This is a top view of the first branching distribution at each level;

[0024] Figure 8 Front view of the distribution of lateral roots in odd and even order;

[0025] Figure 9 A top view of the distribution of lateral roots in odd and even order;

[0026] Figure 10 The figures shown are tensile and shear test diagrams of different parts of the peanut plant in the example, where (a) is the stem tensile test, (b) is the peg tensile test, (c) is the root tensile test, (d) is the stem shear test, (e) is the peg shear test, and (f) is the root shear test.

[0027] Figure 11 The following are tensile test diagrams of the stem and fruit needle nodes in the embodiment, where (a) is before node breakage and (b) is after node breakage.

[0028] Figure 12 This is a simulation diagram of the peanut harvesting process using a chain rake in the embodiment.

[0029] Figure 13 This is a simulation diagram of the peanut harvesting process using a chain rake, illustrating the effect of spreading the peanuts. Detailed Implementation

[0030] Specific implementation method one: Combining Figures 1-9 This embodiment describes a general modeling method for peanut plants based on the discrete element method, which includes the following steps:

[0031] S1, such as Figure 1 As shown, the peanut variety Jinonghua 7, which is representative of Northeast China, was selected as the research object to analyze the geometric morphology and characteristic size parameters of various parts of the peanut plant.

[0032] The geometric shape includes:

[0033] (1) Peanut plant structure and conical characteristics of the main stem and taproot:

[0034] A peanut plant consists of a main stem, primary root, multiple first branches, multiple gynophores, and multiple lateral roots. The main stem and primary root connect end-to-end along the same axis. The junction of the main stem and primary root is defined as the axial starting point. Extending along the length of the main stem and primary root from this starting point, we observe a monotonically decreasing cross-sectional radius, exhibiting a segmented conical characteristic of "rapid decay – slow decay." The region adjacent to the junction is the rapid conical segment, a length on the main stem or primary root transitioning from its maximum radius to a point where the radius gradually decreases. This rapid conical segment is followed by a slow conical segment, whose radius decreases gradually and remains continuous and smooth. The rapid and slow conical segments are geometrically and slope-wise continuous at their junction. Therefore, this invention sets the main stem to consist of one rapid taper segment and three consecutive gradual taper segments, and the main root to consist of one rapid taper segment and two consecutive gradual taper segments. Furthermore, the radii of all constituent spherical particles within each gradual taper segment are constant and fixed values ​​are taken. The arrangement of the rapid and gradual taper segments facilitates the stable reconstruction of the cross-sectional changes of the main stem and main root using a small number of parameters, while also matching the actual stress patterns.

[0035] (2) The pattern of first branching and peg outward expansion:

[0036] like Figure 2 and Figure 3 As shown, both the first branch and the fruit peg have relatively large curvature at their connecting ends (the ends connecting the first branch to the main stem and the first branch to the fruit peg). Starting from the connecting end, the radius gradually decreases along the length direction, while the non-connecting ends (the ends opposite the connecting end) approach linearity, representing a typical "curved connecting ends, straight non-connecting ends" morphology. Unlike the main stem, no significant rapid taper segment was observed in the first branch. The first branch is formed by continuously splicing multiple gradually taper segments along its length, with the growth direction being upward and outward from the connecting end. The fruit peg originates at the connecting end of the first branch and extends downward and outward. The radius difference of the fruit peg is relatively small, and a constant diameter is used in the modeling. The position of the first branch in the global coordinate system is determined by rotating it around the main stem axis, and the fruit peg is also determined by rotating it at the same angle as the main stem.

[0037] (3) Arrangement and simplification of lateral roots:

[0038] Lateral roots are mostly buried underground, making it difficult to observe their stable posture over long periods. To ensure consistency between the lateral roots and the plant's overall morphology and stress transmission, multiple levels of lateral roots are distributed circumferentially at equal intervals in an approximately fan-shaped pattern in the lower part of the main root, with the lateral roots extending downwards and outwards as a whole. The radius of a single lateral root is relatively uniform within the same plant and can be accurately expressed using a constant diameter. The position of the lateral root in the global coordinate system is determined by rotating it around the main root axis.

[0039] like Figures 2-5 As shown, based on observations of the geometric morphology of peanut plants, the characteristic dimensions of peanut plants can be determined to include at least the length and radius of each part, as well as the spreading angle of the connection points of the first branching, pegs, and lateral roots. Tangential angle at non-connected end and quantity The radius can be further subdivided into the maximum radius. and minimum radius This determines the range of granular radii for the main stem, taproot, and first branching. The fruit stalks and lateral roots are measured using the average radius. Determine the radius of its constituent spherical particles. Spread angle at the connecting end. The angle between the tangent at the first branching point, fruit needle, or lateral root and the horizontal direction; the tangential angle at the non-connecting point. The angle between the tangent at the non-connecting end of the first branch, fruit needle, or lateral root and the vertical direction.

[0040] S2. Based on S1, determine the types of spherical particles that make up the geometric model of the peanut plant, including spherical particles composed of each conical segment of the stem, spherical particles composed of the pegs, and spherical particles composed of each conical segment of the root. The stem includes the main stem and the first branch, and the root includes the main root and the lateral root.

[0041] Based on the aforementioned type, the arrangement of the geometric model of the peanut plant consists of the arrangement of the main stem as a sphere, the arrangement of the first branch as a sphere, the arrangement of the pegs as a sphere, the arrangement of the main root as a sphere, and the arrangement of the lateral roots as a sphere.

[0042] Based on the analysis of the main stem and main root in S1, the main stem and main root are arranged into spherical particles using piecewise linear function relationships (including rapid conic sections and slow conic sections).

[0043] Based on the analysis of the first branching, fruit spurs, and lateral roots in S1, the angle of the first branching, fruit spurs, and lateral roots is set to the tangential angle of the line connecting the centers of the constituent spheres. A gradual control method based on cubic function variation is used to arrange the constituent spherical particles.

[0044] S3. Based on the arrangement in S2, the coordinates of the constituent particles in each part of the peanut plant are calculated. The specific process is as follows:

[0045] like Figure 4 As shown, since the aforementioned main stem is composed of one rapid taper segment and three gradual taper segments, the present invention sets the length of each taper segment to be equal to the length of the main stem. The ratio is , , , ,by This is the ratio of the minimum radius to the maximum radius within the rapid taper segment, i.e., the ratio of the radius of the constituent spherical particles within the rapid taper segment to the maximum radius at the main stem connection end. Minimum radius within the rapid tapered section If the number of constituent spheres decreases linearly, then the number of spheres within the rapid conical segment of the main stem is... Represented as:

[0046] (1)

[0047] in, This refers to the length of the rapid taper segment of the main stem. (The number of constituent granules is also relevant.) If the number is not an integer, then in order to more accurately approximate the actual length of the main stem, the number of the constituent particles needs to be rounded to the nearest integer.

[0048] The radius of the constituent spheres within the rapid taper segment of the main stem is expressed as:

[0049] (2)

[0050] in, The first rapid conical segment of the main stem The radius of each constituent particle of the sphere The radius step size of the main stem is used for the radius transition between adjacent constituent spherical particles within the rapid conical segment. Thus strictly satisfying and ,in, The radius of the first constituent sphere within the rapid conical segment of the main stem. The first rapid conical segment of the main stem The radius of each constituent particle.

[0051] The constituent granules within the rapid taper segment of the main stem The axis coordinates are represented as:

[0052] (3)

[0053] in, The first rapid conical segment of the main stem Each of the constituent spherical particles Axis coordinates.

[0054] The radii and number of constituent granules within the three gently conical segments 2, 3, and 4 of the main stem are expressed as follows:

[0055] (4)

[0056] (5)

[0057] in, Main stem The radius of the spherical particles within each gently tapered section For the first The number of constituent spherical particles within each conical segment. The minimum radius of the main stem. The length of the tapered transition segment 2, The length of the tapered transition segment 3, The length of the tapered transition segment 4.

[0058] So, the spherical particles formed in segments 2, 3, and 4 of the gradual conical transition zone... The axis coordinates are represented as:

[0059] (6)

[0060] in, Main stem Within the first gentle conical transition segment Each of the constituent spherical particles Axis coordinates , , Main stem taper segment and the first The first component sphere is tangent to the first Each of the constituent spherical particles Axis coordinates Main stem taper segment and the first The first component sphere is tangent to the first The radius of each constituent particle.

[0061] In summary, the main stem of the first Within the first conical segment Coordinates of each constituent spherical particle Represented as:

[0062] (7)

[0063] Since the aforementioned taper root configuration includes one rapid taper segment and two gradual taper segments, the taper root adopts a multi-tapered parameterization consistent with the main stem. Assume the total length of the taper root is... The length of each conical segment of the main root and the length of the main root The ratios are respectively , , The maximum radius of the main root connection end is The minimum radius of the non-connected end of the main root is .like Figure 3 and Figure 4 As shown, the calculation direction of the principal root is... The axis is in the opposite direction to the calculation direction of the main stem, corresponding to the quantity, radius, and... The axial coordinate formula is also calculated by reversing the direction. Similarly, the radius, number, and... (The sentence is incomplete and requires more context to translate accurately.) The axis coordinates are as follows:

[0064] Number of constituent spheres within the rapid taper segment of the main root for:

[0065] (8)

[0066] in, The length of the rapid conic section of the principal root. It is the ratio of the minimum radius to the maximum radius within the rapid taper segment of the principal root.

[0067] The radius of the constituent spherical particles within the rapid taper segment of the main root is expressed as:

[0068] (9)

[0069] in, The first segment within the rapid conical transformation of the main root The radius of each constituent particle of the sphere The radius step size of the principal root. .

[0070] The constituent spherical particles within the rapid taper segment of the main root The axis coordinates are:

[0071] (10)

[0072] in, The first segment within the rapid conical transformation of the main root Each of the constituent spherical particles Axis coordinates.

[0073] The radii and number of constituent spheres within the two gently conical segments 2 and 3 of the main root are as follows:

[0074] (11)

[0075] (12)

[0076] in, The main root The radius of the spherical particles within each gently tapered section The minimum radius of the principal root. The main root The number of constituent spherical particles within each gradual conical transition segment. The length of the tapered transition segment 2, The length of the tapered transition segment 3.

[0077] The main root has two gently conical segments, 2 and 3, which together form spherical granules. The axis coordinates are represented as:

[0078] (13)

[0079] in, The main root Within the first gentle conical transition segment Each of the constituent spherical particles Axis coordinates The main root taper segment and the first The first component sphere is tangent to the first Each of the constituent spherical particles Axis coordinates The main root taper segment and the first The first component sphere is tangent to the first The radius of each constituent particle.

[0080] In summary, the principal root of the first... Within the first conical segment Coordinates of each constituent spherical particle Represented as:

[0081] (14)

[0082] in, , No. Each taper segment corresponds to one rapid taper segment of the main root ( ) and 2 gentle conical transition sections ( ), The main root The radius of the spherical particles within each tapered section.

[0083] The first branching, fruit spurs, and lateral roots are all measured using the tangential angle of the line connecting the centers of adjacent constituent granules. The gradual control method of cubic function variation makes the tangential angle Angle of expansion from the connection end To the non-connection end angle The transition, while ensuring that adjacent constituent spheres are tangent to each other, can naturally form a shape with "curved connecting ends and approximately straight non-connecting ends." For example... Figure 5As shown, the curvature of the bend is determined by the actual measured unfolding angle of the connection end. Tangential angle between the non-connected ends Controlled, tangential angle The functional expression is as follows:

[0084] (15)

[0085] in, Indicates multiplication. These are the first branching, fruit pegs, or lateral roots, respectively. For the first branch Upper Within the first gentle conical transition segment The constituent spherical particles and the first The tangential angle of the line connecting the centers of the constituent spherical particles. For the first Root and fruit needle Inner The constituent spherical particles and the first The tangential angle of the line connecting the centers of the constituent spherical particles. For the first Roots and lateral roots Inner The constituent spherical particles and the first The tangential angle of the line connecting the centers of the constituent spherical particles. . The angle step size factor, , , The number of constituent granules of the first branch, fruit stalk, or lateral root.

[0086] Unlike the main stem, the first branch does not have a rapid conical segment; instead, it consists of three slow conical segments of equal length. Therefore, the radius and number of the spheres formed by each slow conical segment of the first branch are expressed as follows:

[0087] (16)

[0088] (17)

[0089] in, For the first branch The radius of the spherical particles within each conical segment, at this time These correspond to the three gently conical segments of the first branching. The maximum radius of the first branch. Let be the minimum radius of the first branch. For the first The number of constituent spherical particles in each tapered segment This refers to the length of the first branching of each branch.

[0090] The constituent spherical particles within the first branch The axis coordinates are:

[0091] (18)

[0092] The constituent granules within the fruit needle or lateral root The axis coordinates are:

[0093] (19)

[0094] (20)

[0095] After determining the tangential angle In summary, the local coordinates of the first branch, fruit bud, or lateral root can be obtained, represented as:

[0096] (twenty one)

[0097] in, For the first branch Within the first gentle conical transition segment Each of the constituent spherical particles Axis coordinates For the first The first fruit needle Each of the constituent spherical particles Axis coordinates For the first The first lateral root Each of the constituent spherical particles Axis coordinates For the first branch Upper Within the first gentle conical transition segment The coordinates of the constituent particles of the sphere For the first Root and fruit needle Inner The coordinates of the constituent particles of the sphere For the first Roots and lateral roots Inner The coordinates of the constituent particles of the sphere On the first branch or fruit peg or lateral root, and the first The first component sphere is tangent to the first Each of the constituent spherical particles Axis coordinates On the first branch or fruit peg or lateral root, and the first The first component sphere is tangent to the first The radius of each constituent particle of the sphere For the first branch Upper Within the first gentle conical transition segment The radius of each constituent particle of the sphere For the first Root and fruit needle Inner The radius of each constituent particle of the sphere For the first Roots and lateral roots Inner The radius of each constituent particle of the sphere Indicates multiplication. On the first branch or fruit peg or lateral root, and the first The first component sphere is tangent to the first Each of the constituent spherical particles Axis coordinates. If the first... If a constituent sphere is the starting point of a branch (root), then the coordinates and radius of the constituent sphere that is connected to the main stem, first branch, or main root are represented.

[0098] The local coordinates are transformed to the corresponding global coordinates.

[0099] like Figure 3 As shown, the first branch is divided into different types according to its connection position with the main stem. The first branch of the first stage forms a spherical granule with the bottom of the main stem. The connection is tangential, with the starting point of the first branch at each level and the starting point of the first branch at the next level separated by a constituent granule on the main stem, and so on.

[0100] First branch Number of branches at each level Represented as:

[0101] (twenty two)

[0102] in, This represents the total number of branches in the first branching phase.

[0103] The conversion of the local coordinates of the first branch to global coordinates requires a detour. The axis rotates counterclockwise by a certain angle, such as Figure 6 and Figure 7 As shown, the rotation angle is expressed as:

[0104] (twenty three)

[0105] in, For the first branch Level 1 Branches The angle of counterclockwise rotation of the axis, , This represents the total number of branches in the first branching. Therefore, the first branching revolves around... Axis counterclockwise rotation transformation matrix Represented as:

[0106] (twenty four)

[0107] Therefore, the global coordinates of the first branch are represented as:

[0108] (25)

[0109] like Figure 3 As shown, each branch's first branch is connected to three fruit needles. The starting point of the first fruit needle is connected to the fourth constituent sphere of the first-order branch. Tangential connection, the starting point of the second fruit needle is separated from the starting point of the first fruit needle by three constituent spheres on the first primary branch, and so on, that is, the starting point of each fruit needle is... The global coordinates of the fruit needle only change with the first branch it connects to. The axis is rotated counterclockwise by a certain angle, so the global coordinates of the fruit needle are represented as follows:

[0110] (26)

[0111] The radius of each fruit needle is The number of granules formed by each fruit needle is , The length of each fruit needle, here For the first Root and fruit needles .

[0112] Similar to the first branching, the lateral roots are graded according to their connection points with the main root, with four lateral roots at each grade. The primary lateral roots and the main root form a ball-like structure. Tangential connection, the origin of the secondary lateral root and the origin of the primary lateral root are separated by a main root to form a spherical particle, higher-level lateral root The axis coordinates are located above the lower-order lateral roots, and so on.

[0113] During peanut harvesting, lateral roots are often missing or damaged to varying degrees. Therefore, the number of lateral roots is calculated by converting the length of the main root. The total number of lateral roots is expressed as:

[0114] (27)

[0115] The higher the lateral root level, the more constituent particles it contains. The number of constituent particles per lateral root is expressed as follows:

[0116] (28)

[0117] in, The total length of a single lateral root. , This represents the radius of a sphere composed of a single lateral root.

[0118] The transformation from local coordinates to global coordinates also requires a detour. The axis rotates counterclockwise by a certain angle, and the odd-order lateral roots are more circumferential than the even-order lateral roots. Rotate the axis counterclockwise by 45°, such as Figure 8 and Figure 9 As shown, the rotation angle is expressed as:

[0119] (29)

[0120] in, Representing the lateral root Level 1 Root wrapping The angle of counterclockwise rotation of the axis, .

[0121] Around Axis counterclockwise rotation transformation matrix Represented as:

[0122] (30)

[0123] Therefore, the global coordinates of the lateral root are represented as:

[0124] (31)

[0125] Convert the local coordinates of the first branch, fruit needle, and lateral root to global coordinates, and represent the rotation angle as follows:

[0126] (32)

[0127] in, express No. Level 1 Branches The angle of counterclockwise rotation of the axis, when (Fruit needle) time and (Lateral root) Rotate by the same angle, , express No. The total number of branches (roots) at each level. express The total number.

[0128] In summary, the global coordinates of the first branch, fruit peg, or lateral root can be represented as:

[0129] (33)

[0130] in, Indicates local coordinates around The rotation transformation matrix for counterclockwise rotation of the axis.

[0131] S4. Establish a geometric model of the peanut plant based on the coordinates of the spherical particles that make up different parts of the plant.

[0132] S5. Based on the geometric model of the peanut plant, measure and calibrate the contact mechanical parameters and adhesive mechanical parameters of various parts of the peanut plant. The specific process is as follows:

[0133] Based on a geometric model of the peanut plant, the contact mechanical parameters of various parts of the peanut plant were measured and calibrated using a high-speed camera with methods such as the drop rebound method and the inclined plane method. These contact mechanical parameters included the coefficient of restitution. static friction coefficient and rolling friction coefficient The collision recovery coefficient characterizes the elastic recovery ability of constituent particles or plant organs during mutual collisions, while the static friction coefficient and rolling friction coefficient characterize the frictional resistance between the plant and the soil or machinery surface. The collision recovery coefficient is determined using the drop-rebound method, calculated by controlling the drop height and recording the rebound height. The static friction coefficient and rolling friction coefficient are determined using methods such as the inclined plane method, by slowly changing the angle between the test sample and different contact surfaces, recording the critical slip and rolling initiation states. The above experimental process is combined with a high-speed camera for detailed analysis of the contact process, thereby obtaining contact mechanical parameters suitable for discrete element simulation.

[0134] like Figure 10 and Figure 11 As shown, a universal testing machine was used to perform tensile (normal) and shear (tangential) tests on the test samples, and the load-displacement curves were recorded simultaneously to obtain the adhesive mechanical parameters of various parts of the peanut plant. The adhesive mechanical parameters include the adhesive stiffness coefficient and the adhesive strength. The adhesive stiffness coefficient includes the normal stiffness per unit area. and tangential stiffness per unit area It is obtained based on the slope of the linear elastic segment. Bond strength includes normal strength. and tangential strength The bond strength parameter is determined by the ultimate stress at fracture. It is used to characterize the critical load at which the joint breaks or detaches under tension or shear.

[0135] The adhesive mechanical parameters obtained through the above experiments can be directly used to determine the stiffness and strength threshold of each adhesive bond in the discrete element model, thereby truly reflecting the fracture and shedding characteristics of peanut plants during the harvesting process.

[0136] S6. Add the contact and adhesion mechanical parameters of each part of the peanut plant to the mechanical model. The mechanical model includes a contact model and an adhesion model. The contact model is the Hertz-Mindlin contact model, and the adhesion model is the Bonding model. The specific process is as follows:

[0137] Contact mechanical parameters (impact recovery coefficient) static friction coefficient and rolling friction coefficient Add the adhesive mechanical parameters (normal stiffness per unit area) to the contact model. Tangential stiffness per unit area Normal intensity and tangential strength Add it to the bonding model.

[0138] S7. Input the geometric and mechanical models of the peanut plant into the discrete element method (DEM) software to obtain the peanut plant model based on the DEM method. The DEM software is EDEM.

[0139] Example

[0140] The method of the present invention is illustrated through specific examples. A peanut plant model of Jinonghua No. 7 is created using the general peanut plant modeling method provided by the present invention. The specific steps are as follows:

[0141] 1. Randomly select 20 Jinonghua No. 7 peanut plants, using a precision of 0.01. The characteristic dimensions of peanut plants were measured using digital vernier calipers, and the average parameters are shown in Tables 1 and 2.

[0142] Table 1

[0143]

[0144] Table 2

[0145]

[0146] II. Based on the measured characteristic size parameters of the peanut plants, the plant model parameters are shown in Table 3:

[0147] Table 3

[0148]

[0149] III. The coordinates of the spherical particles that make up each part of the peanut plant are solved, as shown in Table 4:

[0150] Table 4

[0151]

[0152] IV. The contact mechanical parameters of various parts of the peanut plant were measured and are shown in Table 5, including the collision recovery coefficient, static friction coefficient, and rolling friction coefficient.

[0153] Table 5

[0154]

[0155] V. The adhesive mechanical parameters of various parts of the peanut plant were measured and are shown in Table 6, including normal stiffness per unit area, tangential stiffness per unit area, normal strength, and tangential strength.

[0156] Table 6

[0157]

[0158] 6. Input the measured contact mechanical parameters and adhesion mechanical parameters of each part of the peanut plant into the discrete element software to obtain the peanut plant model of Jinonghua No. 7.

[0159] VII. For example Figure 12 and 13 As shown, the peanut plant model of "Jinonghua No. 7" generated in the above steps is imported into discrete element method software to construct a field peanut harvesting simulation experiment:

[0160] Compared to real peanut plants, this peanut plant model has undergone necessary structural simplification by removing the leaves. This treatment significantly reduces the total number of constituent spheres in the peanut plant model, effectively reducing the computational scale while preserving the core mechanical skeleton characteristics of the plant, thereby greatly improving the efficiency and speed of simulation. Meanwhile, the "peanut pod" model appearing in the simulation scenario of this embodiment is only used as a carrier to verify the plant's load characteristics, and it is constructed using the general discrete element multi-sphere filling technique.

[0161] In the simulation verification process, the operating speed of the harvesting implement was set to 0.9 m / s, simulating the process of the digging shovel cutting into the soil and lifting the plant as a whole, as well as the conveying by the chain rake. Thanks to the precise branching angles in the peanut plant model of this invention and the node connection parameter settings based on Bonding V2 (Bonding second-generation model), the plant exhibits flexible bending, adaptive deformation, and elastic rebound behavior consistent with biophysical characteristics when subjected to the violent prying and conveying impact of the chain rake teeth. This effectively overcomes the shortcomings of traditional simplified models that treat the plant as a rigid body, resulting in stiff motion and penetration interference. Simulation results show that the peanut plants simulated by this model can smoothly flip and fall after detaching from the implement, forming continuous, neat, and oriented strips behind the machine. The final laying rate (laying qualification rate) is as high as 98.8%, and the extremely low plant scattering is highly consistent with the actual field operation effect. In summary, the experiment verifies the feasibility of the peanut plant modeling method and can be used for simulation analysis of the peanut harvesting process in segmented peanut harvesting.

[0162] This invention may have other embodiments. Without departing from the spirit and essence of this invention, those skilled in the art can make various corresponding changes and modifications according to this invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A general modeling method for peanut plants based on the discrete element method, characterized in that: It includes the following steps: S1. Analyze the geometric morphology and characteristic dimensions of various parts of the peanut plant; S2. Based on S1, determine the type and arrangement of the spherical particles that make up the geometric model of the peanut plant; The arrangement of the spherical particles in the geometric model of the peanut plant includes: The arrangement of granules in the main stem, the arrangement of granules in the first branching, the arrangement of granules in the fruit stalks, the arrangement of granules in the main root, and the arrangement of granules in the lateral roots; Both the arrangement of the granules forming the main stem and the arrangement of the granules forming the main root are defined using piecewise linear functions. The arrangement of the first branching sphere, the fruit peg sphere, and the lateral root sphere are all defined by the tangential angle of the line connecting the centers of adjacent spheres. Gradual control method for cubic function changes; S3. Based on the arrangement in S2, the coordinates of the constituent particles in each part of the peanut plant are calculated. The specific process is as follows: S31. Based on the arrangement of the main stem constituent spheres using a piecewise linear function relationship, the coordinates of the main stem constituent spheres are obtained as follows: （1） in, Main stem Within the first conical segment The coordinates of the constituent particles of the sphere Indicates the rapid conical segment of the main stem. This indicates the three gently conical segments of the main stem. , For the first The number of constituent spherical particles within each conical segment. The maximum radius of the main stem The radius step length of the main stem, , The ratio of the minimum radius to the maximum radius within the rapid taper segment of the main stem. Main stem taper segment and the first The first component sphere is tangent to the first Each of the constituent spherical particles Axis coordinates Main stem taper segment and the first The first component sphere is tangent to the first The radius of each constituent particle of the sphere Main stem The radius of the spherical particles within each tapered section; S32. Based on the arrangement of the principal root constituent spheres using a piecewise linear function relationship, the coordinates of the principal root constituent spheres are obtained as follows: （2） in, The main root Within the first conical segment The coordinates of the constituent particles of the sphere Indicates the rapid conical segment of the primary root. This indicates the two gently tapering segments of the primary root. , The main root The number of constituent spherical particles within each conical segment. The maximum radius of the principal root. The radius step size of the principal root. , The ratio of the minimum radius to the maximum radius within the rapid conic section of the principal root. The main root The radius of the spherical particles within each gently tapered section The main root taper segment and the first The first component sphere is tangent to the first Each of the constituent spherical particles Axis coordinates The main root taper segment and the first The first component sphere is tangent to the first The radius of each constituent particle; S33, Based on the tangential angle of the line connecting the centers of adjacent constituent spherical particles. The gradual control method based on cubic function variation defines the arrangement of spherical particles in the first branch, the arrangement of spherical particles in the fruit needle, and the arrangement of spherical particles in the lateral root. The tangential angle is also defined. The function is: （3） in, Indicates multiplication. For the first branch or fruit needle or lateral root , For the first branch Within the first gentle conical transition segment The constituent spherical particles and the first The tangential angle of the line connecting the centers of the constituent spherical particles. For the first Root fruit needle inside The constituent spherical particles and the first The tangential angle of the line connecting the centers of the constituent spherical particles. For the first Root lateral root inner first The constituent spherical particles and the first The tangential angle of the line connecting the centers of the constituent spherical particles. , The spreading angle of the first branching point, fruit bud, or lateral root connection point. The tangential angle at the non-connecting end of the first branch, fruit peg, or lateral root. The angle step size factor, , , The number of constituent granules of the first branch, fruit stalk, or lateral root; Based on the radius of the constituent spheres of the first branch, fruit needle, or lateral root and equation (3), the local coordinates of the first branch, fruit needle, or lateral root are obtained: （4） in, For the first branch Within the first gentle conical transition segment The coordinates of the constituent particles of the sphere For the first Root fruit needle inside The coordinates of the constituent particles of the sphere For the first Root lateral root inner first The coordinates of the constituent particles of the sphere For the first branch or fruit peg or lateral root with the first The first component sphere is tangent to the first Each of the constituent spherical particles Axis coordinates For the first branch or fruit peg or lateral root with the first The first component sphere is tangent to the first The radius of each constituent particle of the sphere For the first branch Within the first gentle conical transition segment The radius of each constituent particle of the sphere For the first Root fruit needle inside The radius of each constituent particle of the sphere For the first Roots and lateral roots Inner The radius of each constituent particle of the sphere Indicates multiplication. On the first branch or fruit peg or lateral root, and the first The first component sphere is tangent to the first Each of the constituent spherical particles Axis coordinates; According to equation (4), the global coordinates of the first branch, fruit needle, or lateral root are: （5） in, Indicates local coordinates around The rotation transformation matrix for counterclockwise rotation of the axis. Indicates multiplication; S4. Establish a geometric model of the peanut plant based on the coordinates of the spherical particles that make up each part of the peanut plant. S5. Based on the geometric model of the peanut plant, measure and calibrate the contact mechanical parameters and adhesive mechanical parameters of various parts of the peanut plant. S6. Add the contact mechanical parameters and adhesion mechanical parameters of each part of the peanut plant to the mechanical model to obtain the added mechanical model; S7. Input the geometric model of the peanut plant and the added mechanical model into the discrete element method software to obtain the peanut plant model.

2. The general modeling method for peanut plants based on the discrete element method according to claim 1, characterized in that: The geometric morphology of each part of the peanut plant in S1 includes: A peanut plant consists of a main stem, a taproot, multiple first branches, multiple pegs, and multiple lateral roots; The main stem is defined as consisting of one rapid conical segment and three slow conical segments; the main root consists of one rapid conical segment and two slow conical segments; each branch's first branch consists of multiple slow conical segments; the radius of each fruit spur and each lateral root is a constant value; and the radius of each slow conical segment is a constant value.

3. The general modeling method for peanut plants based on the discrete element method according to claim 2, characterized in that: The geometric model of the peanut plant in S2 consists of spherical particles of various conical segments of the stem, spherical particles of the pegs, and spherical particles of various conical segments of the root. The stem includes the main stem and the first branch, and the root includes the main root and the lateral root.

4. The general modeling method for peanut plants based on the discrete element method according to claim 3, characterized in that: The radius and number of the spherical particles formed by the conical segments of the main root in S32 are... The axis coordinates are as follows: Let the lengths of each conical segment of the principal root be equal to the length of the principal root. The ratios are respectively , , ,but: Number of constituent spherical particles within the rapid taper segment of the main root for: （6） in, The length of the rapid conic section of the principal root; The radius of the constituent spherical particles within the rapid taper segment of the main root is expressed as: （7） in, The first segment within the rapid conical transformation of the main root The radius of each constituent particle; The constituent spherical particles within the rapid taper segment of the main root The axis coordinates are: （8） in, The first segment within the rapid conical transformation of the main root Each of the constituent spherical particles Axis coordinates; The radii and number of constituent spheres within the two gently conical segments 2 and 3 of the main root are as follows: （9） （10） in, The minimum radius of the principal root. The length of the tapered transition segment 2, The length of the tapered transition segment 3; The main root has two gently conical segments, 2 and 3, which together form spherical granules. The axis coordinates are represented as: （11） in, The main root Within the first gentle conical transition segment Each of the constituent spherical particles Axis coordinates.

5. A general modeling method for peanut plants based on the discrete element method according to claim 2, characterized in that: The radii and number of spherical particles formed by the first branching of each gently conical segment in S33 are as follows: （12） （13） in, For the first branch The radius of the spherical particles within each conical segment This indicates the three gently conical segments that form the first branch. The maximum radius of the first branch. Let be the minimum radius of the first branch. For the first The number of constituent spherical particles in each tapered segment The length of the first branch; The first branching forms spherical particles The axis coordinates are: （14） in, For the first branch Within the first gentle conical transition segment Each of the constituent spherical particles Axis coordinates On the first branch or fruit peg or lateral root, and the first The first component sphere is tangent to the first Each of the constituent spherical particles Axis coordinates On the first branch or fruit peg or lateral root, and the first The first component sphere is tangent to the first The radius of each constituent particle of the sphere For the first branch Within the first gentle conical transition segment The radius of each constituent particle of the sphere Indicates multiplication; The number of spheres composed of each fruit needle for: （15） in, The length of each fruit needle, The radius of each fruit needle; The number of granules formed by each lateral root for: （16） in, The radius of a spherical particle composed of a single lateral root. The length of a single lateral root. Indicates multiplication. This indicates the classification of lateral roots by level. , Total number of lateral roots: （17） The fruit needles and lateral roots form a ball-like granule. The axis coordinates are: （18） （19） in, For the first The first fruit needle Each of the constituent spherical particles Axis coordinates For the first The first lateral root Each of the constituent spherical particles Axis coordinates For the first Root fruit needle inside The radius of each constituent particle of the sphere For the first Root lateral root inner first The radius of each constituent particle of the sphere Indicates multiplication; The rotation angle of the first branching, fruit bud, or lateral root is expressed as: （20） in, For the first branch or fruit needle or lateral root , Indicates the first branching, fruit bud, or lateral root. Level 1 Branch or first Root wrapping The angle of counterclockwise rotation of the axis, , Indicates the first branching, fruit bud, or lateral root. The number of branches or roots at each level. This indicates the total number of the first branching, fruit pegs, or lateral roots.

6. The general modeling method for peanut plants based on the discrete element method according to claim 1, characterized in that: The specific process of S5 is as follows: The contact mechanical parameters include the impact recovery coefficient. static friction coefficient and rolling friction coefficient Based on a geometric model of peanut plants, the coefficient of restitution for collisions was determined using a drop-bounce method and a high-speed camera. The static friction coefficient was determined using the inclined plane method. and rolling friction coefficient ; Tensile and shear tests were conducted on peanut plants using a universal testing machine, and load-displacement curves were recorded simultaneously to obtain the adhesive mechanical parameters of various parts of the peanut plant. These parameters included the adhesive stiffness coefficient and adhesive strength. The adhesive stiffness coefficient included the normal stiffness per unit area. and tangential stiffness per unit area Bond strength includes normal strength and tangential strength .

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