A leveling device with automatically adjustable left and right distance for rotary tillers and its adjustment method.

Abstract

This invention discloses a grader with automatically adjustable left and right distances for a rotary tiller and its adjustment method. The grader is installed at the rear of the rotary tiller. A locator is installed on the central axis of the rotary tiller to determine the tillage boundary and establish an absolute coordinate system. Two displacement sensors are symmetrically installed at both ends of the grader to determine the extension and retraction distances at both ends and establish a relative coordinate system with the locator as the origin. Both the locator and the displacement sensors are communicatively connected to a controller. The controller calculates the absolute coordinates of both ends of the grader based on the data in the absolute and relative coordinate systems, and controls the extension and retraction of the hydraulic cylinders connected to both ends of the grader based on the relationship between the absolute coordinates of both ends and the tillage boundary to automatically adjust the extension and retraction distances at both ends of the grader. This invention can automatically control the extension and retraction of the grader, ensuring that the field ridges are not damaged due to operator error, assisting the operator in driving, reducing the difficulty of operation, and improving the leveling effect.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery technology, specifically to a leveler for rotary tillers with automatically adjustable left and right distances and its adjustment method. Background Technology

[0002] The target of a rotary tiller grader is the tilled farmland. The complex and varied field conditions, along with the varying skill levels of operators, limit the effectiveness of rotary tiller graders. Existing rotary tiller graders require manual operation of the control panel to manage the grader's extension and retraction, as well as the distance between the grader and the field ridges to prevent it from hitting the ridges. This demands a high level of operator skill. Furthermore, environmental factors prevent straight-line movement, leading to insufficient leveling in some areas and difficulty turning, increasing work complexity, reducing efficiency, and ultimately decreasing economic benefits.

[0003] Furthermore, existing graders cannot solve the above problems. For example, during driving, when it is not possible to drive in a straight line, the leveling is insufficient; during turning, it is impossible to accurately control the distance between the grader and the field ridge, resulting in scraping the field ridge, which leads to low energy utilization efficiency and low mechanical operation efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a leveler with automatically adjustable left and right distance for rotary tillers and its adjustment method, thereby solving the above-mentioned problems.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] A leveler with automatically adjustable left and right distance for a rotary tiller, the leveler being installed at the rear of the rotary tiller;

[0007] A locator is installed on the central axis of the rotary tiller to determine the rotary tillage boundary and establish an absolute coordinate system;

[0008] Two displacement sensors are symmetrically installed at both ends of the leveler to determine the extension distance at both ends of the leveler and to establish a relative coordinate system with the locator as the origin.

[0009] Both the positioner and the displacement sensor are connected to a controller. The controller calculates the absolute coordinates of both ends of the grader based on the data in the absolute coordinate system and the relative coordinate system. Based on the relationship between the absolute coordinates of both ends of the grader and the rotary tillage boundary, the controller controls the extension and retraction of the hydraulic cylinders connected to both ends of the grader to automatically adjust the extension and retraction distance of both ends of the grader.

[0010] As a further improvement to the above technical solution:

[0011] The controller predicts the absolute coordinates (X, y, t) of the locator after time t according to the following formula. t ,Y t ), the far end of the leveler after time t (X) t1 ,Y t1 ), the near-end coordinates of the leveler after time t (X) t2 ,Y t2 ):

[0012] ψ1=ψ+Δψ

[0013]

[0014] X t =X0+R*(sin(ψ1)-sin(ψ))

[0015] Y t =Y0+R*(cos(ψ)-cos(ψ1))

[0016]

[0017]

[0018] In the above formula, t is the time required for the hydraulic cylinder to retract the distance (L3-L2), where L2 and L3 are the narrowest and widest radii of the grader, respectively, R is the radius of the travel path, v is the tractor's travel speed, and X... o and Y o Let Ψ be the absolute coordinates of the locator, Ψ be the yaw angle, Ψ1 be the predicted yaw angle after time t, and ΔΨ be the yaw angle difference. 31 y 31 (x) represents the relative coordinates of the far end of the leveler. 32 y 32 The relative coordinates of the near end of the leveler.

[0019] The controller controls the extension and retraction of the leveler according to the following rules:

[0020] When the absolute coordinates at both ends of the grader exceed the rotary tillage boundary after the predicted time t, the grader is controlled to shrink.

[0021] When one end of the grader is more than the rotary tillage boundary than the grader's widest radius L3, the controller controls the grader to retract while maintaining its maximum extension state. This is determined based on the following two driving states:

[0022] When the tractor turns, it is necessary to determine whether the center of the turning path exceeds the rotary tillage boundary. If so, it is necessary to determine the telescoping of the land leveler by predicting whether the absolute coordinates of the distal end and the proximal end of the land leveler will go outside the boundary after time t (t is the time required for the hydraulic cylinder to contract the distance (L3 - L2)). Otherwise, calculate the distance from the center of the turning path to the rotary tillage boundary to determine the telescoping of the land leveler;

[0023] When the tractor is traveling in a straight line, it is necessary to predict whether the distance from the absolute coordinates of the positioner of the rotary tiller to the rotary tillage boundary after time t is less than the distance from the distal end of the land leveler to the positioner. If so, control the land leveler to contract.

[0024] The calculation method for the distance between the absolute coordinates of the positioner after time t and the rotary tillage boundary is as follows:

[0025] Predict that the distances from the absolute coordinates of the positioner after time t to the polygonal rotary tillage boundary are T Z1 ,T Z2 ,T Z3 .......T Zn , where n is the number of boundaries, then the minimum distance T from the virtual point Z to the polygonal rotary tillage boundary Zmin is:

[0026] T Zmin =min{T Zn};

[0027] The controller automatically identifies the following three situations:

[0028] When T Zmin > D1, both ends of the land leveler remain in the maximum extended state and will not touch the ridge; where D1 is the distance from the positioner to the distal end of the land leveler;

[0029] When T Zmin < d1, the contraction of the land leveler will also touch the ridge, and a warning will be issued to stop immediately or adjust the steering wheel angle; where d1 is the radius of the positioner from the proximal end of the land leveler;

[0030] When d1 < T Zmin < D1, the land leveler needs to contract, and the contraction distance is L x =D1 - T Zmin .

[0031] When the tractor turns, the method for judging the telescoping of the land leveler is as follows:

[0032] When the center of the turning path is outside the rotary tillage boundary, calculate the distal coordinate and the proximal coordinate of the land leveler after time t, so the following three situations occur:

[0033] When it is predicted that the distal coordinate and the proximal coordinate of the land leveler after time t do not exceed the rotary tillage boundary, control the land leveler to extend;

[0034] When the distal coordinate of the land leveler after predicting for time t exceeds the rotary tillage boundary and the proximal coordinate does not exceed the rotary tillage boundary, the land leveler shrinks;

[0035] When the distal coordinate and the proximal coordinate of the land leveler after predicting for time t exceed the rotary tillage boundary, the land leveler issues a warning and immediately stops or adjusts the steering wheel angle.

[0036] When the center of the turning path is within the rotary tillage boundary, the distances from the absolute coordinate of the locator after time t to the polygonal rotary tillage boundary are T O1 , T O2 , T O3 .......T On (n is the number of boundaries), then the minimum distance T from the absolute coordinate Z of the locator after time t to the polygonal rotary tillage boundary Omin is:

[0037] T Omin = min{T On}}

[0038] Therefore, the following three situations occur:

[0039] When T Omin > D, the land leveler is controlled to extend to the maximum extension state; where D is the radius of the turning path center from the distal end of the land leveler;

[0040] When T Omin < d, the land leveler will touch the ridge when shrinking and will issue a warning and immediately stop or adjust the steering wheel angle; where d is the radius of the turning path center from the proximal end of the land leveler;

[0041] When d < T Omin < D, the land leveler needs to shrink, and the shrinkage distance is L x = D - T Omin .

[0042] The controller calculates the time for early shrinkage according to the shrinkage speed of the hydraulic cylinder and the moving distance of the land leveler;

[0043] Let the shrinkage speed of the hydraulic cylinder be v 液 , the time for the land leveler to shrink to a reasonable range is t1, D is the radius of the turning path center from the distal end of the land leveler, and D1 is the distance from the locator to the distal end of the land leveler:

[0044] When the tractor is moving straight:

[0045] D1 - T Zmin is the shrinkage distance of the land leveler;

[0046] When the tractor turns, and the center of the turning path is within the rotary tillage boundary:

[0047] DT Omin This is the leveler's retraction distance.

[0048] Based on a general inventive concept, the present invention also provides a method for adjusting the extension distance of a leveler with automatically adjustable left and right distance for a rotary tiller, comprising the following steps:

[0049] The controller determines the rotary tillage boundary and establishes an absolute coordinate system based on the signal from the locator;

[0050] The controller determines the extension distance at both ends of the leveler based on the signal from the displacement sensor and establishes a relative coordinate system with the locator as the origin.

[0051] The controller calculates the absolute coordinates of both ends of the leveler based on the data in the absolute and relative coordinate systems.

[0052] The controller determines whether the grader needs to extend or retract based on the relationship between the absolute coordinates of both ends of the grader and the rotary tillage boundary.

[0053] If the grader needs to extend or retract, the controller calculates the advance extension time based on the extension speed of the hydraulic cylinder and the extension distance of the grader, and controls the extension or retraction of the hydraulic cylinder within that time to automatically adjust the extension distance of the grader.

[0054] Compared with the prior art, the advantages of the present invention are:

[0055] 1) During the leveling operation, the grader of the present invention automatically controls the extension and retraction of the grader based on the rotary tillage boundary measured by the locator, ensuring that the grader will not damage the field ridge due to operator error. It can effectively assist the operator in driving, reduce the operator's operating difficulty, reduce time costs, and improve the leveling effect.

[0056] 2) The grader of the present invention can automatically extend and retract, which can greatly increase the flexibility of the machine, reduce the risk of accidentally hitting the field ridge when turning, adapt to more working environments, and improve work efficiency. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the working path of the present invention (showing the easily damaged area of ​​the field ridge).

[0058] Figure 2 This is a schematic diagram illustrating the working principle of the leveler of this invention.

[0059] Figure 3 This is a schematic diagram showing the distance between the absolute coordinates of the locator after time t when the tractor is traveling in a straight line and the sides of the polygonal field boundary ABCD.

[0060] Figure 4 It is a schematic diagram showing the relative coordinates of the center of the turning path and the near and far ends of the grader when the tractor turns (the center of the turning path is within the rotary tillage boundary).

[0061] Figure 5 This is a schematic diagram of the operating radius and collision recognition of the present invention.

[0062] Figure 6 It is a schematic diagram showing the relative coordinates of the center of the turning path and the near and far ends of the grader when the tractor turns (the center of the turning path is outside the rotary tillage boundary).

[0063] Figure 7 This is a schematic diagram of the hydraulic control circuit of the grader of this invention.

[0064] Legend:

[0065] 1. Positioner; 2. Displacement sensor; 3. Field ridge boundary; 4. Oil tank; 5. Filter; 6. Hydraulic pump; 7. Relief valve; 8. Throttle valve; 9. Three-position four-way directional valve; 10. Hydraulic cylinder. Detailed Implementation

[0066] The invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0067] like Figure 1 and Figure 2 As shown, this embodiment features a leveler with automatically adjustable left and right distances for a rotary tiller. The leveler is installed at the rear of the rotary tiller. A locator 1 (preferably GNSS) is installed on the central axis of the rotary tiller to determine the tillage boundary (i.e., the field ridge boundary 3) and establish a planar (X, Y) absolute coordinate system. Two displacement sensors 2 are symmetrically installed at both ends of the leveler to determine the extension / retraction distance at both ends and establish a relative xy coordinate system with the locator as the origin. Both the locator and the displacement sensors are communicatively connected to a controller. The controller calculates the absolute coordinates at both ends of the leveler based on data from the absolute and relative coordinate systems, and controls the extension / retraction of the hydraulic cylinders connected to both ends of the leveler based on the relationship between the absolute coordinates at both ends and the tillage boundary to automatically adjust the extension / retraction distance of the leveler.

[0068] In this embodiment, the specific adjustment method steps are as follows:

[0069] First, determine the vertical distance L1 between the rotary tiller's positioner and the leveler, and the extension range of the leveler (the narrowest radius is L2, and the widest radius is L3).

[0070] Secondly, during the first round of rotary tillage, GNSS is used to determine the tillage boundary and establish a planar (X, Y) absolute coordinate system. Then, during the subsequent leveling process, displacement sensors installed on the leveler are used to determine the leveler's retraction distance L.X And establish the relative coordinates (0, 0) with the locator as the origin o, the x-axis as the centerline of the leveler, and the direction of the vehicle's front as the positive direction. The absolute coordinates of the locator are (X... o ,Y o In the relative coordinate system, the coordinates of the far end of the leveler are (x...). 31 y 31 The near-end coordinates are (x 32 y 32 This allows for the prediction of the absolute coordinates (X, T) of the locator after time t. t ,Y t ), the far end of the leveler after time t (X) t1 ,Y t1 ), the near-end coordinates of the leveler after time t (X) t2 ,Y t2 From this, we can know that:

[0071] ψ1=ψ+Δψ

[0072]

[0073] X t =X0+R*(sin(ψ1)-sin(ψ))

[0074] Y t =Y0+R*(cos(ψ)-cos(ψ1))

[0075]

[0076]

[0077] When the absolute coordinates at both ends of the grader exceed the rotary tillage boundary after the predicted time t, the grader is controlled to shrink.

[0078] When the distance between one end of the grader and the rotary tillage boundary is greater than the widest radius L3 of the grader, the grader is extended.

[0079] Specifically, consider the following two driving conditions:

[0080] 1) When the tractor turns, it is necessary to determine whether the center of the turning path exceeds the rotary tillage boundary. If so, the extension or retraction of the grader is determined by predicting whether the absolute coordinates of the far end and the near end of the grader will be outside the boundary after time t. Otherwise, the extension or retraction of the grader is determined by calculating the distance from the center of the turning path to the rotary tillage boundary.

[0081] 2) When the tractor is traveling in a straight line, it is necessary to determine whether the distance from the absolute coordinate of the rotary tiller's positioner to the rotary tiller boundary after time t is less than the distance from the far end of the leveler to the positioner. If so, the leveler is controlled to retract.

[0082] The specific method is as follows:

[0083] Take the center line of the land leveler as the x-axis, with the front of the vehicle as the positive direction. Make a y-axis perpendicular to the x-axis, and take the left side of the vehicle body as the positive direction to establish a relative coordinate system.

[0084] Let the distance between the front and rear wheels of the tractor be L, the vehicle width be W, when the driving speed of the tractor is v, the radius of the driving path be R, and t be the time required for the hydraulic cylinder to contract the distance (L3 - L2). Then there is:

[0085] ω is the wheel steering angle.

[0086] When ω = 0, the tractor travels straight:

[0087] Predict the absolute coordinates of the locator after t time as Z(X Z , Y Z ):

[0088] X Z = X0 + vt * cos(ψ)

[0089] Y Z = Y0 + vt * sin(ψ)

[0090] As Figure 3 shown, the distances from the absolute coordinates Z of the locator after t time to the polygonal rotary tillage boundary are respectively T Z1 , T Z2 , T Z3 .......T Zn (n is the number of boundaries). Then the minimum distance T Zmin from the absolute coordinates Z of the locator after t time to the polygonal rotary tillage boundary is:

[0091] T Zmin = min{T Zn}

[0092] Therefore, the following three situations occur:

[0093] When T Zmin > D1, then control the land leveler to extend to the maximum extension state; where D1 is the distance from the locator to the far end of the land leveler;

[0094] When T Zmin < d1, the contraction of the land leveler will also touch the ridge, and a warning will be issued to stop immediately or adjust the steering wheel angle; where d1 is the distance from the locator to the near end of the land leveler;

[0095] When d1 < T Zmin < D1, the land leveler needs to contract, and the contraction distance is L x = D1 - T Zmin .

[0096] Basis for judgment:

[0097] like Figure 3 As shown, the distance between the locator and the far end of the leveler is D1:

[0098]

[0099] The distance between the locator and the near end of the leveler is d1:

[0100]

[0101] In this embodiment, the controller calculates the advance retraction time based on the retraction speed of the hydraulic cylinder and the moving distance of the leveler;

[0102] Let the retraction speed of the hydraulic cylinder be v_liquid, and the time for the leveler to retract to a reasonable range be t1:

[0103] D1-T Zmin This is the leveler's retraction distance.

[0104] When the tractor turns:

[0105] Using the center of the turning path as its endpoint, draw a ray in any direction (generally a horizontal ray to the right), and count the number of intersections between the ray and the polygon. If the number is odd, the center of the turning path lies within the rotary tillage boundary.

[0106] When the center of the turning path is outside the rotary tillage boundary, the far-end and near-end coordinates of the grader are calculated after time t. Therefore, the following three scenarios occur:

[0107] If the far-end coordinates and near-end coordinates of the grader after the predicted time t do not exceed the rotary tillage boundary, then control the extension of the grader.

[0108] If the far end coordinates of the grader exceed the rotary tillage boundary after the predicted time t, but the near end coordinates do not exceed the rotary tillage boundary, then the grader will shrink.

[0109] If the far-end coordinates and near-end coordinates of the grader after the predicted time t exceed the rotary tillage boundary, the grader will issue a warning and immediately stop or adjust the steering wheel angle.

[0110] When the center of the turning path is within the rotary tillage boundary, the distances from the absolute coordinates of the locator to the polygonal rotary tillage boundary after time t are respectively T O1 ,T O2 ,T O3 ......T On (where n is the number of boundaries), then the minimum distance T from the absolute coordinate Z of the locator to the polygon rotary tillage boundary after time t is... Omin for:

[0111] T Omin = min{T On}

[0112] Therefore, the following three situations occur:

[0113] When T Omin > D, the leveler is controlled to extend to the maximum extension state; where D is the radius from the center of the turning path to the distal end of the leveler;

[0114] When T Omin < d, the contraction of the leveler will also touch the ridge, and a warning will be issued to stop immediately or adjust the steering wheel angle; where d is the radius from the center of the turning path to the proximal end of the leveler;

[0115] When d < T Omin < D, the leveler needs to contract, and the contraction distance is L x = D - T Omin .

[0116] When the tractor turns right, let ω > 0, as Figure 4 shown, the relative coordinates of the center of the turning path are (x3, y3):

[0117]

[0118] In the relative coordinate system, the distal coordinate of the leveler is (x 31 , y 31 ), and the proximal coordinate is (x 32 , y 32 ),

[0119] Then there are:

[0120] (x 31 , y 31 ): (-L1, L3);

[0121] (x 32 , y 32 ): (-L1, L2).

[0122] When the tractor turns left, let ω < 0, the relative coordinates of the center of the turning path are (x4, y4)

[0123]

[0124] Therefore, the automatic telescopic distance of the leveler can be converted into the distance from the center of the turning path to the rotary tillage boundary.

[0125] Judgment basis

[0126] As Figure 5As shown, when the tractor turns, if the center of the turning path is within the rotary tillage boundary, the radius D of the turning path center from the far end of the grader is:

[0127]

[0128] The radius d of the turning path center from the near end of the leveler is:

[0129]

[0130] In this embodiment, the controller calculates the advance retraction time based on the retraction speed of the hydraulic cylinder and the moving distance of the leveler;

[0131] Let the retraction speed of the hydraulic cylinder be v_liquid, and the time for the leveler to retract to a reasonable range be t1:

[0132] DT Omin This is the leveler's retraction distance.

[0133] like Figure 6 As shown, when the tractor turns, the center of the turning path is outside the rotary tillage boundary. Then, after time t, the far end (X) of the grader... t1 ,Y t1 )for:

[0134]

[0135] The near-end coordinates (X) of the leveler after time t t2 ,Y t2 )for:

[0136]

[0137] like Figure 7 As shown, the hydraulic control in this embodiment of the invention includes two sets of three-position four-way directional valves 9 that control the inlet and outlet oil flow of the hydraulic cylinders 10 at both ends of the grader. The inlet of each three-position four-way directional valve 9 is connected to the output of the hydraulic pump 6 via a throttle valve 8 and a filter 5. The output of the hydraulic pump 6 is also connected to an overflow valve 7, and the input of the hydraulic pump 6 is connected to the oil tank 4 via the filter 5. The outlet of the three-position four-way directional valve 9 is connected to the oil tank, and the two working ports are connected to the upper and lower oil chambers of the corresponding hydraulic cylinders, respectively. During operation, the controller, through simulation and prediction, issues extension / retraction commands to control the reversing and opening adjustment of the three-position four-way directional valves, thereby controlling the direction and flow of the hydraulic oil in the corresponding hydraulic cylinders, causing the hydraulic cylinders 10 at both ends of the grader to extend and retract, thus achieving automatic extension and retraction adjustment of the left and right ends of the grader.

[0138] The above description is merely a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and modifications obtained without departing from the inventive concept should also be considered within the scope of protection of the present invention.

Claims

1. A leveler with automatically adjustable left and right distance for a rotary tiller, the leveler being installed at the rear of the rotary tiller, characterized in that: A locator is installed on the central axis of the rotary tiller to determine the rotary tillage boundary and establish an absolute coordinate system; Two displacement sensors are symmetrically installed at both ends of the leveler to determine the extension distance at both ends of the leveler and to establish a relative coordinate system with the locator as the origin. Both the positioner and the displacement sensor are connected to a controller. The controller calculates the absolute coordinates of both ends of the grader based on the data in the absolute coordinate system and the relative coordinate system. Based on the relationship between the absolute coordinates of both ends of the grader and the rotary tillage boundary, the controller controls the extension and retraction of the hydraulic cylinders connected to both ends of the grader to automatically adjust the extension and retraction distance of both ends of the grader. The controller determines the extension and retraction of the grader based on the following two driving states: When the tractor turns, it is necessary to determine whether the center of the turning path exceeds the rotary tillage boundary. If so, the extension or retraction of the grader is determined by predicting whether the absolute coordinates of the far end and the near end of the grader will be outside the boundary after time t. Otherwise, the extension or retraction of the grader is determined by calculating the distance from the center of the turning path to the rotary tillage boundary. When the tractor is traveling in a straight line, it is necessary to predict whether the distance from the absolute coordinate of the rotary tiller's positioner to the rotary tiller boundary after time t is less than the distance from the far end of the grader to the positioner. If so, the grader should be controlled to retract. When traveling in a straight line, the method for calculating the distance between the absolute coordinates of the locator and the rotary tillage boundary after time t is as follows: The distances from the absolute coordinate Z of the locator to the boundary of the polygonal rotary tillage after time t are predicted to be T. Z1 ,T Z2 ,T Z3 ......T Zn Where n is the number of boundaries, then the minimum distance T from the absolute coordinate Z of the locator after time t to the boundary of the polygonal rotary tillage is... Zmin for: T Zmin =min{T Zn }; The controller automatically identifies the following three situations: When T Zmin At time D1, both ends of the leveler are at their maximum extension and will not touch the field ridge; where D1 is the distance between the locator and the far end of the leveler. When T Zmin <is less than d1, the contraction of the land leveler will also touch the ridge, and a warning will be issued to stop immediately or adjust the steering wheel angle; where d1 is the distance between the locator and the proximal end of the land leveler. When d1 < T Zmin When <D1, the leveller needs to contract, and the contraction distance is L x = D1 - T Zmin ; The method for determining the extension / retraction of the grader when the tractor turns is as follows: When the center of the turning path is outside the rotary tillage boundary, the far-end and near-end coordinates of the grader are calculated after time t. Therefore, the following three scenarios occur: If the far-end coordinates and near-end coordinates of the grader after the predicted time t do not exceed the rotary tillage boundary, then control the extension of the grader. If the far end coordinates of the grader exceed the rotary tillage boundary after the predicted time t, but the near end coordinates do not exceed the rotary tillage boundary, then the grader will shrink. When the far-end coordinates and near-end coordinates of the grader after the predicted time t exceed the rotary tillage boundary, the grader will issue a warning and immediately stop or adjust the steering wheel angle. When the center of the turning path is within the rotary tillage boundary, the distances from the absolute coordinates of the locator to the polygonal rotary tillage boundary after time t are respectively T O1 ,T O2 ,T O3 ......T On Where n is the number of boundaries, then the minimum distance T from the absolute coordinate Z of the locator after time t to the boundary of the polygonal rotary tillage is... Omin for: T Omin =min{T On } Therefore, the following three situations may occur: When T Omin When the value is greater than D, the grader is controlled to extend to its maximum extension state; where D is the radius of the turning path center from the far end of the grader. When T Omin <is less than d, the contraction of the land leveler will also touch the ridge, and a warning will be issued to stop immediately or adjust the steering wheel angle; where d is the radius from the center of the turning path to the proximal end of the land leveler. When d < T Omin <When D, the land leveler needs to contract, and the contraction distance is L x = D - T Omin .

2. The leveler with automatically adjustable left and right distance for a rotary tiller according to claim 1, characterized in that, The controller predicts the absolute coordinates (X) of the locator after time t according to the following formula. t ,Y t The absolute coordinates (X) of the far end of the leveler after time t. t1 ,Y t1 The absolute coordinates (X) of the near end of the leveler after time t. t2 ,Y t2 ): In the above formula, t is the time required for the hydraulic cylinder to retract the distance (L3-L2), where L2 and L3 are the narrowest and widest radii of the grader, respectively, R is the radius of the travel path, v is the tractor's travel speed, and X... o and Y o Let Ψ be the absolute coordinates of the locator, Ψ be the yaw angle, Ψ1 be the predicted yaw angle after time t, and ΔΨ be the yaw angle difference. 31 y 31 (x) represents the relative coordinates of the far end of the leveler. 32 y 32 () represents the relative coordinates of the near end of the leveler.

3. The leveler with automatically adjustable left and right distance for a rotary tiller according to claim 2, characterized in that, The controller controls the extension and retraction of the leveler according to the following rules: When the absolute coordinates at both ends of the grader exceed the rotary tillage boundary after the predicted time t, the grader is controlled to shrink. When the distance between one end of the grader and the rotary tillage boundary is greater than the widest radius L3 of the grader, the grader is extended.

4. The leveler with automatically adjustable left and right distance for a rotary tiller according to claim 1, characterized in that, The controller calculates the advance retraction time based on the retraction speed of the hydraulic cylinder and the extension distance of the leveler; Let the retraction speed of the hydraulic cylinder be v. 液 The time it takes for the leveler to retract to a reasonable range is t 1: When the tractor is traveling in a straight line: D1-T Zmin This is the leveler's retraction distance; When the tractor turns, and the center of the turning path is within the rotary tillage boundary: DT Omin This is the leveler's retraction distance.

5. A method for adjusting the telescopic distance of a leveler with automatically adjustable left-right distance for a rotary tiller as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) The controller determines the rotary tillage boundary and establishes an absolute coordinate system based on the signal from the locator; (2) The controller determines the extension distance at both ends of the leveler based on the signal from the displacement sensor and establishes a relative coordinate system with the locator as the origin; (3) The controller calculates the absolute coordinates of both ends of the leveler based on the data in the absolute coordinate system and the relative coordinate system; (4) The controller determines whether the leveler needs to be extended or retracted based on the relationship between the absolute coordinates of both ends of the leveler and the rotary tillage boundary; (5) If the grader needs to extend or retract, the controller calculates the advance extension time based on the extension speed of the hydraulic cylinder and the extension distance of the grader, and controls the extension or retraction of the hydraulic cylinder within this time to automatically adjust the extension distance of the grader.

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