A method for adjusting the depth of furrow of a hilly land seeder

Abstract

The application provides a hilly land seeder furrowing depth adjusting method, including the following steps: step 1, installing a position sensor on a seeder frame to obtain the slope, fluctuation and distance from the ground of the ploughed ground; step 2, according to the obtained ground slope, fluctuation and distance from the ground, the profiled position of the parallel four-bar linkage of the seeder is actively adjusted through a driver 4 to ensure that the disc furrower reaches the specified depth; step 3, when the depth limiting wheel fully contacts the ground, whether the pressure reaches the preset value is detected through a force sensor, if the preset value is not reached, the position of the parallel four-bar linkage is adjusted until the pressure reaches the preset value and then furrowing operation is carried out.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of agricultural production, and particularly relates to a method for adjusting the furrowing depth of a seeding machine in hilly land. BACKGROUND

[0002] At present, seeding machines are widely used in relatively flat farmland in plain areas, and the furrowing depth adjustment is mainly achieved by parallel four-bar profiling, mechanical spring depression and depth limiting wheel ground contact to ensure the consistency of the furrowing depth. However, the existing seeding machines cannot adapt to the terrain characteristics of large ground slope and frequent changes in hilly and mountainous areas. In actual operation, there are problems such as serious inconsistency of furrowing depth and seed bareness, which seriously affect the quality of seeding operation and the final crop yield. Therefore, it is urgent to develop a furrowing depth control technology for hilly and mountainous areas to achieve consistent furrowing depth. According to the terrain characteristics of hilly and mountainous areas, the present application provides a method for adjusting the furrowing depth of a seeding machine suitable for hilly and mountainous areas, which provides theoretical guidance for the development of seeding machines in hilly and mountainous areas and ultimately improves the level of seeding mechanization in hilly and mountainous areas. SUMMARY

[0003] The purpose of the present application is to provide a method for adjusting the furrowing depth of a seeding machine in hilly land, which comprises the following steps:

[0004] Step 1: Install a position sensor on the seeding machine frame to obtain the slope, fluctuation and distance from the ground of the farmland ground;

[0005] Step 2: According to the obtained ground slope, fluctuation and distance from the ground data, actively adjust the profiling position of the parallel four-bar linkage of the seeding machine through the driver 4 to ensure that the disc furrower reaches the specified depth;

[0006] Step 3: When the depth limiting wheel fully contacts the ground, detect whether the pressure reaches the preset value through the force sensor. If the preset value is not reached, adjust the position of the parallel four-bar linkage until the pressure reaches the preset value and then perform the furrowing operation.

[0007] Further, step 1 comprises the following steps:

[0008] According to the structure and function of the seeding machine, select the appropriate type of position sensor;

[0009] Determine the installation position and direction of the position sensor, select appropriate mounting brackets and fixing parts according to the shape and size of the seeding machine frame, and fix the position sensor on the seeding machine frame so that it can effectively detect the changes of the farmland ground;

[0010] Connect the power supply and signal lines of the position sensor to the power supply and controller or display of the seeding machine according to the output mode and wiring mode of the position sensor;

[0011] Adjust the sensitivity and detection range of the position sensor according to the type and characteristics of the position sensor, and set the sensitivity and detection range of the position sensor to accurately obtain the slope, undulation and distance from the ground of the cultivated land surface.

[0012] Further, the position sensor selects an inertial measurement unit integrating a three-axis accelerometer and a three-axis gyroscope.

[0013] Further, the specific steps of obtaining the slope, undulation and distance from the ground of the cultivated land surface are:

[0014] An adaptive calibration method is used to calibrate the data of the position sensor to eliminate or reduce the influence of errors and improve the accuracy and reliability of the data.

[0015] Using the calibrated data of the position sensor, the attitude angle of the seeding machine, i.e. the pitch angle, roll angle and yaw angle, is calculated through the attitude solving algorithm, and using the attitude angle and acceleration data, the position coordinates of the seeding machine, i.e. the x and y coordinates in the horizontal direction and the z coordinate in the vertical direction, are calculated through integral operation.

[0016] The slope, undulation and distance from the ground of the cultivated land surface are calculated using the attitude angle and position coordinates of the seeding machine through geometric relationships, and the calculation formula of the slope is:

[0017] Where S is the slope, θ is the pitch angle, and φ is the roll angle.

[0018] The calculation formula of the undulation is: Where R is the undulation, (x1, y1, z1) and (x2, y2, z2) are two adjacent position coordinates.

[0019] The calculation formula of the distance from the ground is D=z, where D is the distance from the ground and z is the position coordinate in the vertical direction.

[0020] Further, step 2 includes the following steps:

[0021] The slope, undulation and distance from the ground of the cultivated land surface obtained by the position sensor are transmitted to the controller of the seeding machine.

[0022] Adaptive control is used to calculate the profile position of the parallel four-bar linkage, i.e. the angle and length of the upper and lower pull rods, which need to be adjusted;

[0023] According to the calculated profile position, the angle and length of the upper and lower pull rods are actively adjusted by the driver 4 to make the profile position of the parallel four-bar linkage adapt to the ups and downs of the ground, so as to ensure that the disc opener reaches the specified depth.

[0024] Further, the specific steps for calculating the profile position of the parallel four-bar linkage that needs to be adjusted by adaptive control are as follows:

[0025] According to the geometric structure and motion characteristics of the parallel four-bar linkage, the motion equation and constraint equation of the parallel four-bar linkage are established to describe the relationship between the angle and length of the upper and lower pull rods of the parallel four-bar linkage and the position and attitude of the disc opener;

[0026] According to the principle and method of adaptive control, a suitable adaptive controller is designed, which can calculate the angle and length of the upper and lower pull rods of the parallel four-bar linkage that need to be adjusted in real time according to the slope, ups and downs of the cultivated land and the distance data from the ground;

[0027] According to the design of the adaptive controller, it is realized on the controller or display of the seeding machine and connected with the position sensor and the driver to form a closed-loop control system, which receives the data of the position sensor in real time, compares it with the set value, calculates the deviation signal, generates control input through the adaptive controller, drives the actuator to adjust the position of the parallel four-bar linkage, makes the disc opener reach the specified depth, and at the same time detects the pressure of the depth limiting wheel on the ground through the force sensor, if there is deviation, fine-tune until satisfactory results are achieved.

[0028] Further, the design of the adaptive controller includes the following steps:

[0029] According to the expected position and attitude of the disc opener, a reference model is designed as the target output of the adaptive controller;

[0030] According to the motion equation and constraint equation of the parallel four-bar linkage, a control law is designed, which can calculate the control input, i.e. the angle and length of the upper and lower pull rods of the parallel four-bar linkage, according to the output of the reference model and the actual output of the parallel four-bar linkage;

[0031] According to the motion equation and constraint equation of the parallel four-bar linkage, an adaptive law is designed, which can update the parameter estimation value in real time according to the actual output and control input of the parallel four-bar linkage to reduce the parameter estimation error.

[0032] Further, the motion equation and constraint equation of the parallel four-bar linkage are derived by the following method:

[0033] Suppose the coordinates of the four rotating pairs of the parallel four-bar are A(x1, y1), B(x2, y2), C(x3, y3), D(x4, y4), wherein A and C are fixed shafts, and B and D are movable shafts;

[0034] Suppose the lengths of the four members of the parallel four-bar are l1, l2, l3, l4, wherein l1 = l3, l2 = l4;

[0035] Suppose the angles of the four members of the parallel four-bar are θ1, θ2, θ3, θ4, wherein θ1 = θ3, θ2 = θ4;

[0036] According to the geometric relationship, the following four motion equations are obtained:

[0037] x2 - x1 = l1 cos θ1

[0038] y2 - y1 = l1 sin θ1

[0039] x4 - x3 = l3 cos θ3

[0040] y4 - y3 = l3 sin θ3

[0041] According to the constraint of the invariable length of the members, the following two constraint equations are obtained:

[0042]

[0043]

[0044] Substituting the motion equations into the constraint equations, x2, y2, x4, y4 can be eliminated, and the following two equations about θ1 and θ3 are obtained:

[0045]

[0046]

[0047] Subtracting the above two equations, the following equation about θ1 and θ3 is obtained:

[0048]

[0049] Dividing both sides of the above equation by 4l1l3, the following equation about θ1 and θ3 is obtained, which is the motion equation of the parallel four-bar:

[0050]

[0051] Further, step 3 comprises the following steps:

[0052] According to different soil types and crop categories, select the appropriate preset pressure value to ensure that the disc opener can reach the specified depth;

[0053] Start the seeder, make the depth wheel contact the ground, monitor the pressure of the depth wheel and the ground in real time through the force sensor, and transmit the pressure data to the controller of the seeder;

[0054] Compare the pressure data and the preset value, if the pressure data is less than the preset value, it means that the contact of the depth wheel and the ground is not tight enough, the position of the parallel four bar needs to be adjusted to make the depth wheel descend and increase the pressure with the ground; if the pressure data is greater than the preset value, it means that the contact of the depth wheel and the ground is too tight, the position of the parallel four bar needs to be adjusted to make the depth wheel ascend and reduce the pressure with the ground;

[0055] Repeat the above steps until the pressure data and the preset value are equal or close, at this time it means that the contact of the depth wheel and the ground has reached the best state, and the ditching operation can be carried out.

[0056] Compared with the prior art, the present application has the following beneficial effects:

[0057] 1) The present application proposes a ditching depth adjustment method suitable for hilly and mountainous areas, based on the topographic characteristics of hilly and mountainous areas, the ditching depth is quickly adjusted according to the ground slope and fluctuation, greatly reducing the instability in the ditching operation process, and a ditching depth adjustment method suitable for hilly and mountainous area seeder is invented;

[0058] 2) The present application creatively transfers the consistency problem of the ditching depth of the hilly and mountainous area seeder from how to passively profile the hilly and mountainous terrain to how to actively adjust the seeder ditching operation parameters, greatly reducing the implementation difficulty and improving the consistency and stability of the ditching depth of the seeder. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 It is a flow chart of a hilly and mountainous area seeder ditching depth adjustment method;

[0060] Figure 2 It is a schematic diagram of hilly and mountainous area seeder ditching operation;

[0061] Figure 3 It is a schematic diagram of typical hilly and mountainous terrain.

[0062] The reference signs in the figure are:

[0063] 1 - tractor, 2 - parallel four bar, 3 - position sensor, 4 - driver, 5 - seeder, 6 - depth wheel, 7 - disc opener, 8 - seeder frame, 9 - force sensor. DETAILED DESCRIPTION

[0064] For the purposes of making the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the drawings in the embodiments of the present application. Identical or similar reference numerals in the drawings represent identical or similar elements or elements having identical or similar functions throughout. The described embodiments are part of the embodiments of the present application, but not all the embodiments.

[0065] All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts fall within the scope of protection of the present application.

[0066] The embodiments described below with reference to the drawings and the directional words are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application.

[0067] In a broad embodiment of the present application, a method for adjusting the furrowing depth of a hilly land seeder includes the following steps:

[0068] Step 1: Install a position sensor on the seeder frame to obtain the slope, undulation and distance from the ground of the ploughed ground;

[0069] Step 2: According to the obtained ground slope, undulation and distance from the ground data, actively adjust the profiling position of the parallel four-bar linkage of the seeder through the driver 4 to ensure that the disc furrower reaches the specified depth;

[0070] Step 3: When the depth limiting wheel is in full contact with the ground, detect whether the pressure reaches the preset value through the force sensor, if not, adjust the position of the parallel four-bar linkage until the pressure reaches the preset value and then perform the furrowing operation.

[0071] Further, step 1 includes the following steps:

[0072] According to the structure and function of the seeder, select the appropriate type of position sensor;

[0073] Determine the installation position and direction of the position sensor, select appropriate mounting brackets and fixing parts according to the shape and size of the seeder frame, and fix the position sensor on the seeder frame so that it can effectively detect the changes in the ploughed ground;

[0074] Connect the power supply and signal line of the position sensor, according to the output mode and wiring mode of the position sensor, connect the power supply line of the position sensor to the power supply of the seeder, and connect the signal line of the position sensor to the controller or display of the seeder;

[0075] The sensitivity and detection range of the position sensor are adjusted according to the type and characteristics of the position sensor, so that the slope, undulation and distance from the ground of the farmland ground can be accurately obtained.

[0076] Further, the position sensor selects an inertial measurement unit integrating a three-axis accelerometer and a three-axis gyroscope.

[0077] Further, the specific steps of obtaining the slope, undulation and distance from the ground of the farmland ground are:

[0078] An adaptive calibration method is used to calibrate the data of the position sensor to eliminate or reduce the influence of errors and improve the accuracy and reliability of the data.

[0079] Using the calibrated data of the position sensor, the attitude angle of the seeding machine, i.e. the pitch angle, roll angle and yaw angle, is calculated through an attitude solving algorithm, and using the attitude angle and acceleration data, the position coordinates of the seeding machine, i.e. the x and y coordinates in the horizontal direction and the z coordinate in the vertical direction, are calculated through integral operation.

[0080] The slope, undulation and distance from the ground of the farmland ground are calculated using the attitude angle and position coordinates of the seeding machine through geometric relationships, and the calculation formula of the slope is:

[0081] Where S is the slope, θ is the pitch angle, and φ is the roll angle.

[0082] The calculation formula of the undulation is: Where R is the undulation, (x1, y1, z1) and (x2, y2, z2) are two adjacent position coordinates.

[0083] The calculation formula of the distance from the ground is D=z, where D is the distance from the ground and z is the position coordinate in the vertical direction.

[0084] Further, step 2 includes the following steps:

[0085] The slope, undulation and distance from the ground of the farmland ground obtained by the position sensor are transmitted to the controller of the seeding machine.

[0086] The profiled position of the parallel four-bar linkage that needs to be adjusted, i.e. the angle and length of the upper and lower pull rods, is calculated using adaptive control.

[0087] According to the calculated profiled position, the angle and length of the upper and lower pull rods are actively adjusted by the driver 4 to make the profiled position of the parallel four-bar linkage adapt to the undulation of the ground, so as to ensure that the disc opener reaches the specified depth.

[0088] Further, the specific steps for calculating the profiled position of the parallel four-bar linkage that needs to be adjusted by adaptive control are as follows:

[0089] According to the geometric structure and motion characteristics of the parallel four-bar linkage, the motion equation and constraint equation of the parallel four-bar linkage are established to describe the relationship between the angles and lengths of the upper and lower pull rods and the position and attitude of the disc opener;

[0090] According to the principle and method of adaptive control, a suitable adaptive controller is designed, which can calculate the angles and lengths of the upper and lower pull rods of the parallel four-bar linkage that need to be adjusted in real time according to the slope, undulation and distance from the ground of the cultivated ground;

[0091] According to the design of the adaptive controller, it is realized on the controller or display of the seeder, connected with the position sensor and the driver, forming a closed-loop control system, which receives the data of the position sensor in real time, compares it with the set value, calculates the deviation signal, generates the control input through the adaptive controller, drives the actuator to adjust the position of the parallel four-bar linkage, so that the disc opener reaches the specified depth, and at the same time detects the pressure of the depth limiting wheel on the ground through the force sensor, and if there is deviation, it will be fine-tuned until the desired effect is achieved.

[0092] Further, the design of the adaptive controller includes the following steps:

[0093] According to the expected position and attitude of the disc opener, a reference model is designed as the target output of the adaptive controller;

[0094] According to the motion equation and constraint equation of the parallel four-bar linkage, a control law is designed, which can calculate the control input, i.e. the angles and lengths of the upper and lower pull rods of the parallel four-bar linkage, according to the output of the reference model and the actual output of the parallel four-bar linkage;

[0095] According to the motion equation and constraint equation of the parallel four-bar linkage, an adaptive law is designed, which can update the parameter estimation value in real time according to the actual output and control input of the parallel four-bar linkage, so as to reduce the parameter estimation error.

[0096] Further, the motion equation and constraint equation of the parallel four-bar linkage are derived by the following method:

[0097] Assume that the coordinates of the four rotating pairs of the parallel four-bar linkage are A(x1, y1), B(x2, y2), C(x3, y3), and D(x4, y4), where A and C are fixed axes, and B and D are movable axes;

[0098] Assume that the lengths of the four members of the parallel four-bar linkage are l1, l2, l3 and l4, where l1 = l3 and l2 = l4;

[0099] Suppose the angles of the four members of the parallel four-bar are θ1, θ2, θ3, θ4, where θ1 = θ3, θ2 = θ4;

[0100] According to the geometric relationship, the following four motion equations are obtained:

[0101] x2-x1 = l1cosθ1

[0102] y2-y1 = l1sinθ1

[0103] x4-x3 = l3cosθ3

[0104] y4-y3 = l3sinθ3

[0105] According to the constraint of the invariable length of the members, the following two constraint equations are obtained:

[0106]

[0107]

[0108] Substituting the motion equations into the constraint equations, x2, y2, x4, y4 can be eliminated, and the following two equations about θ1 and θ3 are obtained:

[0109]

[0110]

[0111] Subtracting the above two equations, the following equation about θ1 and θ3 is obtained:

[0112]

[0113] Dividing both sides of the above equation by 4l1l3, the following equation about θ1 and θ3 is obtained, which is the motion equation of the parallel four-bar:

[0114]

[0115] Further, step 3 comprises the following steps:

[0116] According to different soil types and crop categories, select the appropriate preset pressure value to ensure that the disc opener can reach the specified depth;

[0117] Start the seeding machine, make the depth limiting wheel contact the ground, monitor the pressure of the depth limiting wheel and the ground in real time through the force sensor, and transmit the pressure data to the controller of the seeding machine;

[0118] Compare the pressure data with the preset value. If the pressure data is less than the preset value, it means that the depth limiting wheel is not in close contact with the ground. The position of the parallel four rods needs to be adjusted to lower the depth limiting wheel and increase the pressure with the ground. If the pressure data is greater than the preset value, it means that the depth limiting wheel is in close contact with the ground. The position of the parallel four rods needs to be adjusted to raise the depth limiting wheel and reduce the pressure with the ground.

[0119] Repeat the above steps until the pressure data is equal to or close to the preset value. At this point, it indicates that the contact between the depth limiting wheel and the ground has reached the optimal state, and trenching operations can be carried out.

[0120] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, and the present invention will be further described in detail.

[0121] like Figures 1-3 As shown, this implementation uses a seeder 5 as the main body. The components of the seeder 5 are mounted on the seeder frame 8, and the tractor 1 pulls the seeder for operation. The process for adjusting the furrow depth is as follows: Figure 1 As shown, the furrowing depth adjustment components of the seeder include: a parallel four-bar linkage 2, a driver 4, a depth limiting wheel 6, a disc furrow opener 7, a position sensor 3, and a force sensor 9. When performing sowing and furrowing operations in hilly and mountainous areas, the position sensor 3 installed on the seeder 5 detects the ground slope and undulation data, and controls the driver 4 to drive the parallel four-bar linkage 2 to move to the set position, pushing the disc furrow opener 7 into the soil. The force sensor 9 installed on the depth limiting wheel 6 detects the pressure, and furrowing is completed when the set pressure is reached. The sowing and furrowing operations are repeated to complete the operation.

[0122] The method for adjusting the furrowing depth of a seeder in hilly and mountainous areas described in this invention is a fundamental method for automating the sowing machinery in hilly and mountainous areas. The seeder 5 is an exemplary general term for various types of sowing machinery and does not specifically refer to any one type of seeder, including but not limited to mechanical spring type, hydraulic drive type, ultrasonic identification type and infrared identification type seeders.

[0123] The position sensor 3 described in this invention refers to an exemplary general term for various position recognition technologies, including but not limited to visual recognition, laser recognition, ultrasonic recognition, and infrared recognition.

[0124] The force sensor 9 described in this invention refers to a general term encompassing various force recognition technologies, including but not limited to: strain gauge force sensors, capacitive force sensors, resistance strain gauge force sensors, piezoelectric force sensors, and micro-strain sensors.

[0125] The driver 4 mentioned in this invention refers to an exemplary general term for various driving technologies, including but not limited to electric drive, hydraulic drive, pneumatic drive, etc.

[0126] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the same. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of adjusting the depth of furrow of a hill planter, comprising: The method comprises the following steps: Step 1: installing a position sensor on the seeding machine frame to obtain the slope, undulation and distance from the ground of the ploughed land; Step 2: actively adjusting the profiling position of the parallel four-bar linkage of the seeding machine through the driver (4) according to the obtained ground slope, undulation and distance from the ground to ensure that the disc opener reaches the specified depth; Step 3: detecting whether the pressure reaches the preset value through the force sensor when the depth limiting wheel fully contacts the ground, and if not, adjusting the position of the parallel four-bar linkage until the pressure reaches the preset value and then performing the ditching operation; Step 2 comprises the following steps: transmitting the slope, undulation and distance from the ground of the ploughed land obtained by the position sensor to the controller of the seeding machine; calculating the profiling position of the parallel four-bar linkage, i.e. the angle and length of the upper and lower pull rods, through adaptive control; and actively adjusting the angle and length of the upper and lower pull rods through the driver (4) according to the calculated profiling position, so that the profiling position of the parallel four-bar linkage adapts to the undulation of the ground to ensure that the disc opener reaches the specified depth; The specific steps of calculating the profiling position of the parallel four-bar linkage through adaptive control are as follows: establishing the motion equation and constraint equation of the parallel four-bar linkage according to its geometric structure and motion characteristics to describe the relationship between the angle and length of the upper and lower pull rods and the position and posture of the disc opener; designing a suitable adaptive controller according to the principle and method of adaptive control, so that it can calculate the angle and length of the upper and lower pull rods of the parallel four-bar linkage in real time according to the slope, undulation and distance from the ground of the ploughed land; and realizing the adaptive controller in the controller or display of the seeding machine, connecting it with the position sensor and the driver to form a closed-loop control system, receiving the data of the position sensor in real time, comparing it with the set value, calculating the deviation signal, generating the control input through the adaptive controller, driving the exciter to adjust the position of the parallel four-bar linkage, so that the disc opener reaches the specified depth, and at the same time detecting the pressure of the depth limiting wheel on the ground through the force sensor, and if there is a deviation, fine-tuning is performed until a satisfactory result is achieved.

2. The method of adjusting the depth of furrow of a hill planter according to claim 1, wherein, Step 1 comprises the following steps: According to the structure and function of the seeding machine, selecting a suitable type of position sensor; Determining the installation position and direction of the position sensor, selecting suitable mounting brackets and fixing parts according to the shape and size of the seeding machine frame, and fixing the position sensor on the seeding machine frame so that it can effectively detect the changes of the ploughed land; Connecting the power supply and signal lines of the position sensor, connecting the power supply line of the position sensor to the power supply of the seeding machine and connecting the signal line of the position sensor to the controller or display of the seeding machine according to the output mode and wiring mode of the position sensor; Adjusting the sensitivity and detection range of the position sensor, setting the sensitivity and detection range of the position sensor according to its type and characteristics so that it can accurately obtain the slope, undulation and distance from the ground of the ploughed land.

3. The method of claim 2, wherein, The position sensor selects an inertial measurement unit integrating a three-axis accelerometer and a three-axis gyroscope.

4. The method of claim 1, wherein, The specific steps for acquiring the slope, undulation and distance from the ground of the cultivated land surface are as follows: An adaptive calibration method is adopted to calibrate the data of the position sensor, so as to eliminate or reduce the influence of errors and improve the accuracy and reliability of the data; By using the calibrated data of the position sensor, the attitude angles of the seeding machine, i.e. the pitch angle, the roll angle and the yaw angle, are calculated through an attitude solution algorithm, and by using the attitude angles and the acceleration data, the position coordinates of the seeding machine, i.e. the x and y coordinates in the horizontal direction and the z coordinate in the vertical direction, are calculated through integral operation. The slope, the fluctuation and the distance data of the ground of the cultivated land are calculated by using the attitude angle and the position coordinate of the seeding machine, and the slope is calculated by the following formula: Wherein, S is the slope, θ is the pitch angle, and φ is the roll angle; the fluctuation is calculated by the following formula: Wherein, R is the fluctuation, (x1, y1, z1) and (x2, y2, z2) are two adjacent position coordinates. The calculation formula of the distance from the ground is D = z, wherein D is the distance from the ground and z is the position coordinate in the vertical direction.

5. The method of claim 1, wherein, The design of the adaptive controller includes the following steps: According to the expected position and attitude of the disc opener, a reference model is designed as the target output of the adaptive controller; According to the motion equation and constraint equation of the parallel four-bar linkage, a control law is designed, which can calculate the control input, i.e. the angles and lengths of the upper and lower pull rods of the parallel four-bar linkage, according to the output of the reference model and the actual output of the parallel four-bar linkage; According to the motion equation and constraint equation of the parallel four-bar linkage, an adaptive law is designed, which can update the parameter estimation value in real time according to the actual output and the control input of the parallel four-bar linkage, so as to reduce the parameter estimation error.

6. The method of adjusting the depth of opening of a hillside seeder according to claim 1, wherein The motion equation and constraint equation of the parallel four-bar linkage are derived by the following method: Assume that the coordinates of the four rotating pairs of the parallel four-bar linkage are A(x1, y1), B(x2, y2), C(x3, y3) and D(x4, y4), wherein A and C are fixed shafts and B and D are movable shafts; Assume that the lengths of the four members of the parallel four-bar linkage are l1, l2, l3 and l4, wherein l1 = l3 and l2 = l4; Assume that the angles of the four members of the parallel four-bar linkage are θ1, θ2, θ3 and θ4, wherein θ1 = θ3 and θ2 = θ4; According to the geometric relationship, the following four motion equations are obtained: x2-x1 = l1cosθ1 y2-y1 = l1sinθ1 x4-x3 = l3cosθ3 y4-y3 = l3sinθ3 According to the constraint of constant member length, the following two constraint equations are obtained: Substituting the motion equations into the constraint equations can eliminate x2, y2, x4 and y4, and the following two equations about θ1 and θ3 are obtained: Subtracting the above two equations can obtain the following equation about θ1 and θ3: Dividing both sides of the above equation by 4l1l3 can obtain the following equation about θ1 and θ3, which is the motion equation of the parallel four-bar linkage:

7. The method of adjusting the depth of opening of a hillside seeder according to claim 1, wherein According to different soil types and crop species, select the appropriate preset pressure value to ensure that the disc opener can reach the specified depth; Start the seeding machine, make the depth limiting wheel contact the ground, monitor the pressure between the depth limiting wheel and the ground in real time through the force sensor, and transmit the pressure data to the controller of the seeding machine. Compare the pressure data with the preset value. If the pressure data is less than the preset value, it means that the contact between the depth limiting wheel and the ground is not tight enough, and the position of the parallel four-bar linkage needs to be adjusted to make the depth limiting wheel descend and increase the pressure on the ground. If the pressure data is greater than the preset value, it means that the contact between the depth limiting wheel and the ground is too tight, and the position of the parallel four-bar linkage needs to be adjusted to make the depth limiting wheel ascend and reduce the pressure on the ground. Repeat the above steps until the pressure data is equal to or close to the preset value, at which point the contact between the depth limiting wheel and the ground has reached the optimal state, and the trenching operation can be performed.

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