Method for assisting a coupling operation to be performed on a three-point linkage

Description

[0001] The invention relates to a method for assisting a coupling process to be carried out on a three-point power lift of an agricultural tractor, in which the three-point power lift has right and left lower links, on which tractor-side coupling points are provided for attaching an attachment interface, which can be adjusted by means of an adjusting arrangement with regard to a spread dimension, a lateral offset and / or a height position.

[0002] The routine attachment of agricultural implements to a three-point linkage requires appropriate operator experience, as the tractor-side coupling points located at the free ends of the lower links, usually catch hooks for receiving corresponding coupling balls, are generally not visible from the driver's cab of the agricultural tractor. A possible misalignment relative to the attachment-side coupling points to be attached to them is therefore not readily apparent to the operator and may require repeated exit from the driver's cab to manually correct the lower link position. A prior art method for attaching an agricultural implement is known from US 2021 / 127544 A1.

[0003] In view of this, it is the object of the present invention to develop a method of the type mentioned at the outset with regard to a convenient attachment of an attachment interface to a three-point linkage of an agricultural tractor.

[0004] This object is achieved by a method having the features of patent claim 1.

[0005] In the method according to the invention for supporting a coupling process to be carried out on a three-point power lift of an agricultural tractor, the three-point power lift has right and left lower links, on which tractor-side coupling points are provided for attaching an attachment interface of an attachment, which can be adjusted by means of an adjusting arrangement with regard to a spread dimension, a lateral offset and / or a height position.In a starting position assumed by the agricultural tractor, a control unit determines an actual spatial position of the attachment-side coupling points of the attachment interface relative to the tractor-side coupling points by means of image capture and analysis using an imaging device, wherein the agricultural tractor is moved along a predetermined trajectory into an end position intended for the attachment of the attachment and the actuating arrangement is controlled by the control unit in accordance with the course of the predetermined trajectory such that the tractor-side coupling points assume a spatial target position intended for the attachment of the attachment-side coupling points.

[0006] This relieves the operator of the need to manually adjust the lower link arms to a position suitable for attaching the attachment interface. The operator is then only responsible for specifying the direction and speed of the agricultural tractor when negotiating the curve.

[0007] The tractor-side coupling points provided at the free ends of the lower links are generally formed by catch hooks into which coupling balls encompassed by the attachment interface or the attachment-side coupling points can be engaged.

[0008] The spread describes the horizontal distance between the tractor-side coupling points, whereas the lateral offset represents the joint horizontal deflection of the tractor-side coupling points from a centered or neutral position. The height position also refers to the vertical distance between the tractor-side coupling points relative to the ground surface. To enable the appropriate adjustment of the two lower links, they are each pivoted at one end on the tractor side by means of corresponding ball joints in both horizontal and vertical directions. To change the spread and lateral offset, the adjustment arrangement includes individually length-adjustable lateral stabilizers that run between the respective lower link and a tractor-side support point and can be operated hydraulically or electrically.The change in height position, however, is carried out by means of a hydraulic lifting mechanism of standard design, which is also part of the adjustment arrangement.

[0009] The target position of the tractor-side coupling points, which the control unit transforms into corresponding values ​​for spread, lateral offset, and height position based on the assumed known geometry of the three-point power lift used, is ideally specified by the control unit in such a way that the catch hooks, in the final position of the agricultural tractor intended for attachment of the attachment, are aligned below the coupling balls of the attachment interface in such a way that the lower links only need to be raised far enough to attach the attachment interface using the hydraulic lifting gear until the coupling balls securely engage in the catch hooks. The top link of the three-point power lift is then hooked by hand into an upper coupling point of the attachment interface. This completes the coupling process and the attachment is ready for operation.

[0010] Advantageous further developments of the method according to the invention emerge from the subclaims.

[0011] To determine the actual spatial position, the control unit preferably performs a preliminary optical identification of the attachment coupling points. This can be done either by the operator by marking the attachment coupling points visualized via an operating and display unit, or automatically based on the image capture and analysis performed using a previously trained neural network, in particular a so-called convolutional neural network. For this purpose, the agricultural tractor is moved to a starting position within a permissible tolerance range for performing the coupling process.

[0012] If the starting position is outside the permissible tolerance range, which is detected by the control unit based on the actual position of the attachment-side coupling points relative to the tractor-side coupling points, as well as the assumed known adjustment range of the lateral stabilizers or the hydraulic lifting gear used, taking into account the specific kinematic model of the agricultural tractor, the coupling process can be aborted and the operator informed. Such a situation arises, for example, if the agricultural tractor is positioned at an unfavorable angle of attack and too close to the attachment, making it impossible to move it into a suitable final position for attaching the attachment without repeated maneuvering.

[0013] The imaging device used for image acquisition and analysis can be a stereo camera, an RGB camera, or a 3D laser scanner, which optically records the spatial position of the attachment-side coupling points from the agricultural tractor. In the case of a rear power lift, the imaging device is located in the rear area of ​​the agricultural tractor. The imaging device also allows optical recording of the attachment-side coupling points for visualization on the control and display unit.

[0014] At the same time, the imaging system can be used to monitor the area around the three-point linkage. Obstacles along the curve to be negotiated can be detected in a timely manner, allowing the coupling process to be aborted if necessary and the operator to be informed.

[0015] There are various options for specifying the trajectory curve.

[0016] In the case of an operator-specified setting, the control unit can dynamically adjust the target position and thus the spread, lateral offset, and / or height of the tractor-side coupling points based on the observed actual path. The actual path is derived from the operator-specified direction and speed settings and is determined by the control unit based on GPS-based position information or by recording the position of the steerable front wheels in conjunction with the travel speed of the agricultural tractor.

[0017] If the control unit determines, based on a kinematic model specific to the agricultural tractor, that the agricultural tractor cannot be moved to a suitable end position for attaching the attachment coupling points along the observed trajectory curve, the coupling process is aborted. At the same time, the operator can be informed of the abort. This is the case if the required target position cannot be set at the tractor-side coupling points, as otherwise the adjustment range of the lateral stabilizers or the hydraulic lifting gear used would be exceeded.

[0018] Alternatively, the control unit can also compute the course of the trajectory based on a kinematic model of the agricultural tractor. If the trajectory is computed, the control unit can permanently set the target position and thus the spread, lateral offset, and / or height of the tractor-side coupling points. The operator can then be guided along the trajectory using GPS, with its course, including the corresponding steering commands, being displayed cartographically on the control and display unit. Appropriate voice instructions can also be issued. Alternatively, it is also conceivable for the specified trajectory to be traversed with autonomous steering by an associated vehicle control system, while the operator still controls the travel speed.Such a vehicle control system is known under the name "AutoTrac" in agricultural tractors manufactured by John Deere.

[0019] The method according to the invention for assisting a coupling process to be performed on a three-point linkage of an agricultural tractor is described in more detail below with reference to the attached drawings. They show: Fig. 1 shows a schematically illustrated embodiment of an arrangement for carrying out the method according to the invention, Fig. 2 shows a representation of a coupling process to be carried out on a three-point power lift of an agricultural tractor, and Fig. 3 shows an embodiment of the method according to the invention shown as a flow chart.

[0020] Fig. 1shows an embodiment of an arrangement 10 for carrying out the method according to the invention for supporting a three-point linkage 12 of an agricultural tractor 14 according to Fig. 2 coupling process to be carried out.

[0021] As in Fig. 2As can be seen, the three-point linkage 12 has right and left lower links 16, 18, to which tractor-side coupling points 20, 22 are provided for attaching an attachment interface 24, which can be adjusted by means of an adjusting arrangement 26 with regard to a spread, a lateral offset and / or a height position. Furthermore, there is an upper link 28, which can be hooked into an upper coupling point 30 of the attachment interface 24. By way of example, the attachment 32 to be attached to the three-point linkage 12 is designed as a rotary rake 34, but alternatively it can also be a mounted or towed attachment of any other design.

[0022] The tractor-side coupling points 20, 22 provided at the free ends of the lower links 16, 18 are formed by catch hooks 36, 38, into which coupling balls 44, 46 encompassed by the attachment interface 24 or attachment-side coupling points 40, 42 can be engaged. The spread dimension describes a horizontal distance d between the catch hooks 36, 38, whereas the lateral offset represents a common horizontal deflection s of the catch hooks 36, 38 from a centered or neutral center position 48 (as an example in Fig. 2 a deflection s to the left is indicated, but this can just as well be in the opposite direction). The height position also refers to a vertical distance h of the catch hooks 36, 38 relative to the earth's surface 50.

[0023] The distances defined in this respect each refer to a geometric center point of the respective tractor-side coupling point 20, 22.

[0024] To enable the two lower links 16, 18 to be adjusted accordingly, they are each pivotably connected at one end on the tractor side by means of corresponding ball joints 52, 54 in both horizontal and vertical directions. To change the spread and lateral offset, the adjustment assembly 26 includes individually length-adjustable lateral stabilizers 56, 58, which extend between the respective lower link 16, 18 and a tractor-side support point 60, 62 in the area of ​​a rear axle differential housing 64 and can be actuated hydraulically in this case. The height position is changed by means of right and left lifting cylinders 66, 68 of a hydraulic lifting mechanism 70, which is also part of the adjustment assembly 26.

[0025] According to Fig. 1An electronic control unit 72 serves as a component of the arrangement 10 comprised by the agricultural tractor 14 for controlling the actuating arrangement 26, for which purpose the latter comprises a plurality of valves 74 which can be electrically actuated by the control unit 72 and which interact with a hydraulic system 76 of the agricultural tractor 14 in such a way that the hydraulic side stabilizers 56, 58 or the lifting cylinders 66, 68 assigned to the hydraulic lifting mechanism 70 can be extended and retracted in a controlled manner.

[0026] An imaging device 78 in the form of a stereo camera, an RGB camera or a 3D laser scanner communicating with the control unit 72 serves to optically record the spatial position of the attachment-side coupling points 40, 42 from the agricultural tractor 14. In the case of the Fig. 2 The imaging device 78 of the rear power lift shown is located in the rear area of ​​the agricultural tractor 14.

[0027] The attachment-side coupling points 40, 42, optically detected by the imaging device 78, are visualized, among other things, on an operating and display unit 80 connected to the control unit 72. The latter is designed as a touch-sensitive display and is located in a driver's cab 82 of the agricultural tractor 14.

[0028] In addition, the assembly 10 includes further components connected to the control unit 72. These are a navigation system 84, a voice output unit 86, and a vehicle control system 88 for autonomously steering the agricultural tractor 14. Such a vehicle control system 88 is known as "AutoTrac" in agricultural tractors manufactured by John Deere.

[0029] The functioning of the arrangement 10 will now be explained with reference to the Fig. 3shown flowchart, which represents an embodiment of the method according to the invention.

[0030] The method executed by the control unit 72 is initialized in a start step 100 upon commissioning of the agricultural tractor 14, after which a query is made in a first step 102 as to whether the operator desires to perform a coupling process between the agricultural tractor 14 and the attachment 32. If this is the case, which the operator indicates by corresponding input via the control and display unit 80, the process continues with a second step 104. Otherwise, the process returns to the first step 102.

[0031] In the second step 104, the control unit 72 first performs an environmental detection using the imaging device 78. The purpose of this is to identify the attachment interface 24 located within the detection range or the attachment-side coupling points 40, 42 encompassed by it. Identification occurs either by the operator by marking the attachment-side coupling points 40, 42 visualized via the operating and display unit 80, or automatically by means of image capture and analysis using a previously trained neural network, in particular a so-called convolutional neural network. The imaging device 78, which communicates with the control unit 72, is used to perform the image capture and analysis.

[0032] After successful identification of the attachment-side coupling points 40, 42, their actual spatial position relative to the tractor-side coupling points 20, 22 is determined in a third step 106. The actual position is determined as part of the image acquisition and analysis performed by the control unit 72 in the second step 104.

[0033] The determined actual position is used in a fourth step 108 by the control unit 72 to check whether the agricultural tractor 14 is in a starting position 90 that lies within a tolerance range permissible for carrying out the coupling process.

[0034] If the starting position 90 lies outside the permissible tolerance range, which is detected by the control unit 72 based on the determined actual position of the attachment-side coupling points 40, 42 relative to the tractor-side coupling points 20, 22, as well as the assumed known adjustment range of the lateral stabilizers 56, 58 or the hydraulic lifting gear 70 used, taking into account the specific kinematic model of the agricultural tractor 14, the coupling process is aborted, and the method returns to the first step 102. At the same time, the control unit 72 initiates the output of corresponding operator information via the operating and display unit 80 located in the driver's cab 82.Such a situation arises, for example, when the agricultural tractor 14 is at an unfavourable angle of attack at too short a distance from the attachment 32, so that it cannot be brought into an end position 92 suitable for attaching the attachment 32 without repeated maneuvering.

[0035] If, however, the control unit 72 detects in the fourth step 108 that the starting position 90 assumed by the agricultural tractor 14 lies within the permissible tolerance range, the operator is prompted in a fifth step 110 via the operating and display unit 80 to start the coupling process by moving the agricultural tractor 14 towards the attachment 32. For this purpose, the agricultural tractor 14 is moved along a predetermined trajectory curve 94 into the end position 92 intended for attaching the attachment 32, wherein the actuating arrangement 26 is controlled by the control unit 72 in accordance with the course of the predetermined trajectory curve 94 such that the tractor-side coupling points 20, 22 assume a spatial target position intended for attaching the attachment-side coupling points 40, 42. At the same time, the imaging device 78 is used to monitor the surroundings in the area of ​​the three-point linkage 12.Obstacles located along the path curve 94 to be traversed are thus detected in good time so that the coupling process can be aborted if necessary and the operator can be informed of this by appropriately controlling the operating and display unit 80.

[0036] The target position of the tractor-side coupling points 20, 22, which the control unit 72 transforms into corresponding values ​​for the spread dimension, lateral offset and height position on the basis of the geometry of the three-point power lift 12 used, which is assumed to be known, is specified by the control unit 72 in the fifth step 110 such that the catch hooks 36, 38 come to lie in alignment below the coupling balls 44, 46 of the attachment interface 24 in the end position 92 of the agricultural tractor 14 intended for attaching the attachment 32, such that the lower links 16, 18 only have to be raised by means of the hydraulic lifting gear 70 to such an extent that the coupling balls 44, 46 securely engage in the catch hooks 36, 38 in order to attach the attachment interface 24. The top link 28 of the three-point linkage 12 is then hooked by hand into the upper coupling point 30 of the attachment interface 24.This completes the coupling process and the attachment 32 is ready for operation. The process is then terminated in a final step 112.

[0037] There are various options for specifying trajectory curve 94. Operator-side specification

[0038] In the case of an operator-side specification, the control unit 72 dynamically adjusts the target position and thus the spread, the lateral offset, and / or the height position of the tractor-side coupling points 20, 22 according to an observed actual course of the trajectory curve 94. The actual course of the trajectory curve 94 results from the operator-side travel direction and travel speed specifications and is determined by the control unit 72 based on position information obtained by means of the navigation system 84 using GPS or by recording the position of the steerable front wheels in conjunction with the travel speed of the agricultural tractor 14.

[0039] If the control unit 72 determines, based on a kinematic model specific to the agricultural tractor 14, that the agricultural tractor 14 cannot be moved into the end position 92 suitable for attaching the attachment-side coupling points 40, 42 along the observed course of the trajectory curve 94, the coupling process is aborted, and the method returns to the first step 102. At the same time, the control unit 72 initiates the output of corresponding operator information via the operating and display unit 80 located in the driver's cab 82. This is the case if the setting of the required target position at the tractor-side coupling points 20, 22 is not possible, since otherwise the adjustment range of the lateral stabilizers 56, 58 used or the hydraulic lifting gear 70 would be exceeded. Calculation specification

[0040] Alternatively, the course of the trajectory curve 94 is mathematically specified by the control unit 72 based on a kinematic model of the agricultural tractor 14. If the trajectory curve 94 is mathematically specified, the control unit 72 permanently sets the target position and thus the spread, the lateral offset, and / or the height position of the tractor-side coupling points 20, 22 at the beginning of the coupling process. The operator is then guided along the trajectory curve 94 to be traversed using GPS, for which purpose its course, including corresponding steering commands, is displayed cartographically on the operating and display unit 80 at the instigation of the navigation system 84. In addition, corresponding voice instructions are output via the voice output unit 86.Alternatively, the specified trajectory curve 94 can also be traversed by the vehicle control system 88 performing the steering autonomously, while the specification of the travel speed remains left to the operator.

Claims

1. Method for assisting a coupling operation to be carried out at a three-point powerlift of an agricultural tractor, in which the three-point powerlift (12) has right and left lower links (16, 18) at which tractor-side coupling points (20, 22) for attaching an implement interface (24) of an implement (32) are provided, which coupling points can be adjusted with respect to a spreading extent (d), a lateral offset (s) and / or a height position (h) by means of an actuator arrangement (26), wherein, in a starting position (90) taken up by the agricultural tractor (14), a control unit (72) is used to determine, by image capture and analysis by means of an imaging device (78), a spatial actual position of implement-side coupling points (40, 42) of the implement interface (24) relative to the tractor-side coupling points (20, 22), wherein the agricultural tractor (14) is brought along a predetermined trajectory (94) into an end position (92) provided for the attachment of the implement (32), characterized in that the actuator arrangement (26) is activated by the control unit (72) in accordance with the course of the predetermined trajectory (94) in such a manner that the tractor-side coupling points (20, 22) take up a spatial desired position provided for attaching the implement-side coupling points (40, 42).

2. Method according to Claim 1, characterized in that, in order to determine the spatial actual position, an optical identification of the implement-side coupling points (40, 42) is carried out in advance by the control unit (72).

3. Method according to Claim 1 or 2, characterized in that the imaging device (78) used for the image capture and analysis is in the form of a stereocamera, an RGB camera or a 3D laser scanner.

4. Method according to Claim 3, characterized in that monitoring of the surroundings in the region of the three-point powerlift (12) is carried out by means of the imaging device (78).

5. Method according to at least one of Claims 1 to 4, characterized in that, in the event of an operator-side stipulation of the trajectory (94), the desired position and therefore the spreading extent (d), the lateral offset (s) and / or the height position (h) of the tractor-side coupling points (20, 22) is dynamically adapted by the control unit (72) in accordance with an observed actual course of the trajectory (94).

6. Method according to Claim 5, characterized in that the coupling operation is stopped if the control unit (72) determines on the basis of a kinematic model specific to the agricultural tractor (14) that the agricultural tractor (14) cannot be brought along the observed course of the trajectory (94) into an end position (92) suitable for attaching the implement-side coupling points (40, 42).

7. Method according to at least one of Claims 1 to 4, characterized in that the course of the trajectory (94) is predetermined computationally by the control unit (72) on the basis of a kinematic model of the agricultural tractor (14).

8. Method according to Claim 7, characterized in that, in the event of a computational stipulation of the trajectory (94), the desired position and therefore the spreading extent (d), the lateral offset (s) and / or the height position (h) of the tractor-side coupling points (20, 22) is fixedly set by the control unit (72).