Creation method of six-bar subsoiler mechanism for hilly field production based on mole-like and agriculture

Abstract

The present application relates to the trajectory generation and synthesis field of six-bar subsoiling mechanism for hilly farmland. The purpose is to map the mole forefoot soil digging trajectory to the bionic subsoiling trajectory based on the bionics principle of animal soil digging, and to improve the trajectory combined with the subsoiling agronomy requirements. The improved bionic subsoiling trajectory is used as the target trajectory, and a creation method of six-bar subsoiling mechanism with reproducible target trajectory is provided. The technical scheme is: a creation method of six-bar subsoiling mechanism for hilly farmland based on mole and agronomy; comprising: 1 mapping the mole forefoot soil digging trajectory to the bionic subsoiling trajectory; 2 combining the subsoiling agronomy requirements to improve the bionic subsoiling trajectory to disturb the shallow soil as small as possible, and using the improved bionic subsoiling trajectory as the target trajectory; 3 selecting 16 type value points to discretize the continuous target trajectory as target trajectory points; 4 taking the Stephenson III type six-bar mechanism as an example, the position function of the trajectory generating point is written.

Description

TECHNICAL FIELD

[0001] The present application relates to the trajectory generation and synthesis field of six-bar subsoiling mechanism for hilly farmland, and particularly relates to a creation method of six-bar subsoiling mechanism for hilly farmland based on mole simulation and agriculture. BACKGROUND

[0002] As the main content of conservation tillage, subsoiling technology refers to a kind of soil loosening method that can reach a depth of more than 25 cm and break the plough pan. The hilly farmland in China has the characteristics of complex terrain and scattered distribution. It is extremely inconvenient to use large-scale traction subsoiling method. At present, the main mechanical tillage method is small rotary tiller. The subsoiling tillage depth is insufficient and cannot break the plough pan. CN109601026A discloses a soil subsoiling mechanism, which comprises a rack fixing plate, a subsoiling hook, a connecting column and a first elastic element. The rack fixing plate is used for connecting with the rack of the subsoiling machine. The upper end of the subsoiling hook is hinged to the rack fixing plate. The subsoiling mechanism can effectively avoid obstacles and prolong the service life when encountering strong resistance or obstacles. However, the defect of the mechanism is that the disturbance to the shallow soil is too large, which can easily cause water and soil loss and other problems. Therefore, it is urgent to develop a small subsoiling equipment actuator for hilly farmland, which can realize low energy consumption, low tillage resistance and high soil disturbance performance. SUMMARY

[0003] The purpose of the present application is to map the mole forefoot soil digging trajectory to the bionic subsoiling trajectory based on the animal soil digging bionics principle, and to improve the trajectory in combination with the subsoiling agricultural requirements. The improved bionic subsoiling trajectory is used as the target trajectory, and a creation method of six-bar subsoiling mechanism capable of reproducing the target trajectory is provided.

[0004] The technical scheme provided by the present application is as follows:

[0005] A creation method of six-bar subsoiling mechanism for hilly farmland based on mole simulation and agriculture, which comprises the following steps in sequence:

[0006] Step 1: mapping the mole forefoot soil digging trajectory to the bionic subsoiling trajectory;

[0007] Step 2: improving the bionic subsoiling trajectory in combination with the subsoiling agricultural requirements to disturb the shallow soil as little as possible, and using the improved bionic subsoiling trajectory as the target trajectory;

[0008] Step 3: selecting 16 type value points to discretize the continuous target trajectory as target trajectory points;

[0009] Step 4: selecting a configuration from the existing six-bar mechanism type synthesis, for example, writing the position function of the trajectory generating point of the Stephenson III type six-bar mechanism;

[0010] Step 5: Establish the optimization model of the trajectory generation synthesis task of the Stephenson Ⅲ six-bar mechanism;

[0011] Step 6: Solve the optimization model established in Step 5 using the improved differential algorithm to obtain the optimal solution of the mechanism parameters.

[0012] Step 7: Design a Stephenson Ⅲ six-bar subsoiling mechanism capable of reproducing the target trajectory based on the optimal solution obtained in Step 6.

[0013] In Step 1, the plane segment of the mole's front foot plowing trajectory is perpendicular to the ground, while the subsoiling mechanism needs to achieve soil loosening in a plane parallel to the ground. Therefore, the mole's front foot plowing trajectory is flipped to expose the plane segment above the ground and make it parallel to the ground. To break the plow sole layer below 25 cm from the ground surface, the bionic subsoiling trajectory is obtained by analogously enlarging the ratio of the subsoiling depth to the actual plowing depth of the mole's front foot.

[0014] In Step 2, conservation tillage requires the subsoiling implement to disturb the shallow soil as little as possible to ensure the flatness of the surface soil layer, thereby improving issues such as surface runoff and soil erosion. Therefore, in combination with the requirements of subsoiling agriculture, the original bionic trajectory is improved with an inward concave shape to enable the subsoiling mechanism reproducing the improved bionic subsoiling trajectory (i.e., the target trajectory) to immediately withdraw from the shallow soil after disturbing the bottom soil, thereby avoiding large-scale disturbance to the shallow soil.

[0015] In Step 3, the discretization process involves distributing 16 type points onto the target trajectory, with the distance ratio between two adjacent points being less than 2.

[0016] In Step 4, in the Stephenson Ⅲ six-bar mechanism, the P point on the second connecting rod EF is expected to achieve the target trajectory, i.e., the trajectory occurrence point. The position function of the trajectory occurrence point P is:

[0017]

[0018]

[0019] wherein:

[0020] α is the acute angle between the second connecting rod EF and the horizontal direction, ψ is the acute angle between the first connecting rod BC and the horizontal direction, p1 and q1 are the position vectors of E point on the first connecting rod, p2 and q2 are the position vectors of P point on the second connecting rod, A and B are the rotation axis of the crank and the swing point respectively, A point also serves as the coordinate origin, x B , y B are the coordinates of B point.

[0021] In step 5, the optimized model for the Stephenson III six-bar linkage trajectory generation task is as follows:

[0022]

[0023] In the formula: Represents the coordinates of the target trajectory point. The coordinates of the trajectory points that have a sequential pattern are represented; X is a vector composed of all design variables; N = 16, representing the number of ideal target trajectory points; h1(X) takes 0 when the solution vector satisfies the Glasov condition, otherwise it takes 1; h2(X) takes 0 when θ2 is arranged in ascending or descending order, otherwise it takes 1; h3(X) takes 0 when condition (3) is satisfied, otherwise it takes 1; M is the penalty coefficient, which is 100.

[0024] The beneficial effects of the present invention are as follows: the six-bar linkage obtained by the method described in the present invention can not only break the deep plow pan in the soil, but also avoid excessive disturbance to the shallow soil and soil erosion, and improve surface runoff; and the six-bar linkage structure is more stable, has a stronger load-bearing capacity, and is more suitable for high load conditions in deep soil loosening. Attached Figure Description

[0025] Figure 1 This is a diagram of the mole's digging trajectory as described in this invention.

[0026] Figure 2 This is a schematic diagram of the biomimetic deep pine trajectory described in this invention.

[0027] Figure 3 This is a schematic diagram of the target trajectory and target trajectory points described in this invention.

[0028] Figure 4 This is a simplified diagram of the Stephenson III type six-bar linkage described in this invention.

[0029] Figure 5 What is displayed is Figure 4 The dashed line overlapping r1, the position vectors of point E in the first link p1 and q1, and the position vectors of point P in the second link p2 and q2.

[0030] Figure 6 This is a simplified diagram of the solution mechanism and its trajectory described in this invention.

[0031] Figure 7 This is a comparison diagram of the target trajectory point and the occurrence trajectory described in this invention.

[0032] Figure 8 This is a schematic diagram of the Stephenson III type six-bar deep loosening mechanism described in this invention. Detailed Implementation

[0033] The application will be further described below in connection with the embodiments shown in the accompanying drawings.

[0034] The application comprises the following steps:

[0035] Step 1: mapping the mole forepaw soil-throwing trajectory to a bionic subsoiling trajectory;

[0036] In the step 1 (see Figure 1 , the soil part is shown in gray), the mole forepaw soil-throwing trajectory is a closed figure, which is connected by a plane segment and several curved segments with different curvatures; the plane segment (i.e. the return segment in Figure 2 ) is perpendicular to the ground; and the plane segment in the bionic subsoiling trajectory needs to be realized in a plane parallel to the ground, so the mole forepaw soil-throwing trajectory is first flipped until the plane segment is exposed to the ground and parallel to the ground. In addition, since the subsoiling tillage requires breaking the plow pan below 25 cm from the ground surface, the bionic subsoiling trajectory is enlarged according to the ratio between the subsoiling depth and the actual soil-throwing depth of the mole forepaw, and the obtained bionic subsoiling trajectory (see Figure 2 , where the horizontal line through point A represents the ground surface) has an entry segment (AB) corresponding to the subsoiling shovel driven into the soil, a soil-penetrating segment (BC) corresponding to the subsoiling shovel breaking the plow pan soil, an exit segment (CD) corresponding to the subsoiling shovel leaving the soil, and a return segment (DA) corresponding to the subsoiling shovel returning to the entry position for the next soil-throwing cycle.

[0037] Step 2: improving the bionic subsoiling trajectory in combination with the subsoiling agronomic requirements, and taking the improved bionic subsoiling trajectory as the target trajectory;

[0038] In the step 2, the outward convex shape of the original bionic subsoiling trajectory in the exit segment will cause the subsoiling mechanism reproducing the trajectory to cause a large disturbance to the shallow soil, while the conservation tillage requires the subsoiling implement to disturb the shallow soil as little as possible to ensure the flatness of the surface soil layer, thereby improving the problems of surface runoff and soil erosion, etc.; therefore, in combination with the subsoiling agronomic requirements, the exit segment (between points C and D) of the original bionic trajectory is improved in an inward concave manner (see Figure 3 ), so that the subsoiling mechanism reproducing the improved bionic subsoiling trajectory immediately withdraws from the shallow soil after disturbing the bottom soil, avoiding a large area of lifting and turning of the shallow soil.

[0039] Step 3: discretizing the continuous target trajectory with 16 points (see Figure 3 ) as target trajectory points; after dispersing the 16 type value points to the target trajectory, the coordinates of the target trajectory points are:

[0040]

[0041] Step 4: Express the position function of the trajectory generating point of Stephenson Ⅲ six-bar mechanism;

[0042] The improved bionic trajectory shape is singular, and has an inflection point with large curvature. The six-bar mechanism has the advantages of high precision and large solution domain when guiding the singular trajectory of super majority target trajectory points, which is beneficial to find a solution mechanism with high replication precision and meeting the actual installation conditions. In addition, the six-bar mechanism is more stable and has stronger bearing capacity, and is more suitable for the working condition of deep soil, so Stephenson Ⅲ six-bar mechanism is selected to replicate the improved bionic trajectory.

[0043] In the fourth step, the Stephenson Ⅲ six-bar mechanism diagram (see Figure 4 and Figure 5 ), r1, r2, r3, r4, r5, r6, r7, s respectively represent the lengths of the first rack rod AD, the input crank AB, the first connecting rod BC, the first output rod CD, the second connecting rod EF, and the second rocker FG, the second rack rod AG, and the distance from point E to point G; θ0 is the included angle between the first rack rod and the X axis, θ1 is the included angle between the first rack rod and the second rack rod, θ2 is the included angle between the input crank and the first rack rod, which is defined as the input angle, γ is the included angle between the first connecting rod and the first rack rod, ψ is the acute angle between the first connecting rod and the horizontal direction, α is the acute angle between the second connecting rod and the horizontal direction, ζ is the included angle between the second rocker and the line GE, and η is the included angle between the line GE and the X axis; p1 and q1 are the position vectors of point E on the first connecting rod, and p2 and q2 are the position vectors of point P on the second connecting rod.

[0044] Since Figure 4 the part of the dashed line in the figure coincides with the solid line, for the sake of clarity, these coinciding thin dashed lines (the dashed line overlapping with r1, the position vectors p1 and q1 of point E on the first connecting rod, and the position vectors p2 and q2 of point P on the second connecting rod) are shown by Figure 5 .

[0045] The position of point P on the second connecting rod is expected to achieve the target trajectory, i.e. the trajectory generating point. The position function of the trajectory generating point of Stephenson Ⅲ six-bar mechanism is expressed as follows.

[0046] The position equations of points B and D are respectively:

[0047] x B =x A +r2·cos(θ2+θ0)

[0048] y B =y A +r2·sin(θ2+θ0)

[0049] x D =x A+ r1 cos θ0

[0050] y D = y A + r1 sin θ0

[0051] The closed loop equation of Grashof four-bar mechanism ABCD is:

[0052]

[0053] From Euler formula, we have:

[0054] r2 cos θ2 + r3 cos γ - r4 sin θ3 - r1 = 0

[0055] r2 sin θ2 + r3 sin γ - r4 sin θ3 = 0

[0056] Solving the equation set, we have:

[0057]

[0058] Wherein:

[0059] K1' = 2a' r3, K2' = 2b' r3,

[0060] a' = r2 cos θ2 - r1

[0061] b' = r2 sin θ2

[0062] Thus, the position of point E on the connecting rod in Grashof four-bar mechanism can be determined:

[0063]

[0064]

[0065] Wherein,

[0066]

[0067] x C = x B + r3 cos (θ0 + γ)

[0068] y C = y B + r3 sin (θ0 + γ)

[0069] The distance s from point E to point G is:

[0070]

[0071] Wherein,

[0072] xDA = x D - x A

[0073] y DA = y D - y A

[0074] x GD = x G - x D

[0075] y GD = y G - y D

[0076] x G = x A + r7*cos(θ0+θ1)

[0077] y G = y A + r7*sin(θ0+θ1)

[0078] The position of the F point can be determined as follows:

[0079] x F = x A + x DA + x GD + r6*cos(η-ζ)

[0080] y F = y A + y DA + y GD + r6*sin(η-ζ)

[0081] wherein,

[0082]

[0083]

[0084] The position function of the trajectory generating point P of the Stephenson III type six-bar mechanism can be finally obtained as follows:

[0085]

[0086]

[0087] wherein,

[0088] Step 5: Establish the optimization model of the trajectory generation synthesis task of the Stephenson III type six-bar mechanism.

[0089] In the fifth step, in order to make a certain point on the second connecting rod of the Stephenson type Ⅲ six-bar mechanism pass through 16 target trajectory points in turn, the target trajectory points and the corresponding P points with timing rules are used to calculate the sum of squares of horizontal and vertical coordinate deviations between the target trajectory points and the P points, and the sum of squares is taken as the target function:

[0090]

[0091] wherein N=16 represents the number of ideal target trajectory points, and the target function f obj contains all design variables, and a vector X composed of the design variables is as follows:

[0092]

[0093] The target function includes the following constraint conditions:

[0094] (1) Grashof condition for ensuring that the crank can rotate a full circle:

[0095] [Max(r1, r2, r3, r4) + Min(r1, r2, r3, r4)] ≤ {Sum(r1, r2, r3, r4) - [Max(r1, r2, r3, r4) + Min(r1, r2, r3, r4)]}

[0096] (2) Condition for the input angle θ2 to increase or decrease in order:

[0097] When ,

[0098] or, when ,

[0099] (3) Always-assemble condition for the second rocker and the second connecting rod:

[0100] max(s) ≤ r5 + r6

[0101] min(s) ≥ |r5 - r6|

[0102] (4) Range of the parameters to be solved:

[0103] In order to facilitate assembly, θ0 is limited to the interval Considering that the overall structure should not be too large, all the rod length parameters are limited to the interval (0, 500), and the remaining parameters are continuously adjusted and selected within a reasonable range.

[0104] The conditions (1), (2) and (3) are added to the target function as penalty functions, and an optimization model is established with the minimum target function value:

[0105]

[0106] Wherein, h1(X) takes 0 when the solution vector satisfies the Grashof condition, otherwise takes 1; h2(X) takes 0 when θ2 is arranged in ascending or descending power, otherwise takes 1; h3(X) takes 0 when the condition (3) is satisfied, otherwise takes 1; M is the penalty coefficient, which takes 100.

[0107] Step 6: using the improved differential algorithm to solve the optimization model of the trajectory generation synthesis task of the Stephenson III type six-bar mechanism established in the fifth step,

[0108] The principle of the improved differential algorithm is: randomly generate an initial population composed of design variables within the constraint condition range, and perform cyclic mutation, crossover and selection processing on the initial population, until the target function converges, the appearance of the optimal solution makes the algorithm terminate, at this time the optimal solution obtained is the mechanism parameter group that meets the target trajectory requirements. For specific steps, refer to the published document CN113761730A.

[0109] The optimal solution size of the mechanism parameters is:

[0110] r1=415.97mm,r2=100.27mm,r3=266.18mm,r4=269.29mm,

[0111] r5=412.64mm,r6=500.05mm,r7=417.21mm,x0=331.13mm,

[0112] y0=705.62mm,p1=243.67mm,q1=-411.23m,p2=-547.18mm,

[0113] q2=-588.89mm,θ0=178.85°,θ1=8.60°.

[0114] The solution mechanism diagram is shown in Figure 6 , Figure 7 The comparison diagram between the target trajectory points and the trajectory of the solution mechanism is shown in

[0115] Step 7: according to the solution mechanism in the sixth step, a Stephenson III type six-bar deep loosening mechanism is designed (see Figure 8 ). The distance between the two hinge points in each rod is: the rack rod is r1, the crank is r2, the three auxiliary rods are r3, the first rocker is r4, the second rocker is r6, and the execution rod is r5; the deep loosening shovel is a length-adjustable rod.

Claims

1. A method for creating a six-pole deep-plowing mechanism for hilly fields based on mole-inspired design and agronomy, comprising the following steps: Step 1: Map the mole's forefoot digging trajectory to a biomimetic deep-loosening trajectory; Step 2: Based on the requirements of deep tillage agronomy, the biomimetic deep tillage trajectory is improved to minimize the disturbance of the shallow soil. The improved biomimetic deep tillage trajectory is used as the target trajectory. Step 3: Select 16 model points to discretize the continuous target trajectory and use them as target trajectory points; Step 4: Taking the Stephenson III six-bar linkage as an example, write out the position function of the trajectory occurrence point; Step 5: Establish an optimization model for the comprehensive task of generating the trajectory of the Stephenson Type III six-bar linkage; Step 6: Use the improved finite difference algorithm to solve the optimization model established in Step 5 to obtain the optimal solution for the mechanism parameters; Step 7: Based on the optimal solution obtained in Step 6, design a Stephenson III type six-bar deep loosening mechanism that can reproduce the target trajectory; The discretization process in step 3 involves distributing the 16 model points onto the target trajectory, with the ratio of the distances between two adjacent points being less than 2. In step 4, in the Stephenson III six-bar linkage, the second link... EF On P The point location is expected to achieve the target trajectory, i.e., the trajectory occurrence point; trajectory occurrence point P The position function is: in: For the second link EF The angle between the acute angle and the horizontal direction For the first link BC The angle between the acute angle and the horizontal direction p 1 and q 1 To determine the position vector of point E in the first link, p 2 and q 2 To determine P The position vector of point A on the second connecting rod is given. Points A and B are the axis of rotation and the point of oscillation of the crank, respectively. Point A also serves as the origin of the coordinate system. x B , y B Here are the coordinates of point B; In step 5, the optimized model for the Stephenson III six-bar linkage trajectory generation task is as follows: In the formula: Represents the coordinates of the target trajectory point. The coordinates of the trajectory points representing events that occur according to a certain sequential pattern; X It is a vector consisting of all design variables; N =16, representing the number of ideal target trajectory points; The value is 0 if the solution vector satisfies the Glasov condition, and 1 otherwise. exist Take 0 when arranged in ascending or descending order of power; otherwise take 1. The value is 0 when condition (3) is met, and 1 otherwise; M is the penalty coefficient, which is 100. The angle between the input crank and the first frame rod is defined as the input angle. Condition (3) is the condition under which the second rocker and the second link can always be assembled: ； in: For the second link EF Length, For the second joystick FG The length.

2. The method for creating a six-pole deep tillage mechanism for hilly fields based on mole-like behavior and agronomy, as described in claim 1, is characterized in that: In step 1, since the plane segment of the mole's forefoot digging trajectory is perpendicular to the ground, and the deep loosening mechanism needs to achieve soil loosening movement on a plane parallel to the ground, the mole's forefoot digging trajectory is flipped so that the plane segment is exposed on the ground and parallel to the ground; and the biomimetic deep loosening trajectory is obtained by analogy and enlargement according to the ratio of deep loosening depth to the actual digging depth of the mole's forefoot.

3. The method for creating a six-pole deep tillage mechanism for hilly fields based on mole-like models and agronomy, as described in claim 2, is characterized in that: In step 2, in accordance with the requirements of deep tillage agronomy, the soil exit section of the original biomimetic trajectory is modified to be concave, so that after the deep tillage mechanism that reproduces the improved biomimetic deep tillage trajectory disturbs the bottom soil, it immediately extracts the shallow soil to avoid causing large-scale disturbance to the shallow soil.

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