Tractor traction measuring device and measuring method

Abstract

The invention relates to a tractor traction force measuring device and method, the measuring device comprises a tractor side force transmission frame, an agricultural implement side force transmission frame, an integrated traction force sensor, a measuring host and a GNSS antenna, the integrated traction force sensor comprises a sensor body, an axial force measuring full bridge and a shearing force measuring full bridge, the sensor body is also provided with a signal conditioning module which is used for obtaining a pulling force along the axis of the sensor and a shearing force perpendicular to the axis of the sensor, and converting the pulling force and the shearing force into a traction force under a geodetic coordinate system. And the measuring host is used for acquiring the attitude information of the tractor and converting the received traction force from the signal conditioning module under the geodetic coordinate system into the real traction force under the coordinates of the tractor. According to the measuring method, the real traction force of the tractor is measured based on the measuring device. The device is simple and rapid to install, can obtain the real traction force of the tractor in real time, reduces the data processing workload of testers, and improves the measurement precision.

Description

Technical Field

[0001] This invention belongs to the field of tractor testing technology, specifically relating to a tractor traction force measuring device and measuring method. Background Technology

[0002] When a tractor is used to attach agricultural implements, it is often necessary to measure the tractor's traction force. Common traction force measuring devices typically have the following structures: Figure 1 As shown. Typically, when tractor 1 is working, it needs to connect to implement 2 via upper pull rod 3, right lower pull rod 4, and left lower pull rod 5. Therefore, it is generally necessary to install an upper pull rod tension / compression sensor 6, an upper pull rod angle sensor 7, a lower pull rod pin sensor 9, and a lower pull rod angle sensor 8. Then, all the measurement signals are transmitted to a data acquisition device to calculate the tractor 1's traction force. However, this traction force test has the following problems: 1. The upper pull rod needs to be customized, and a tension / compression sensor needs to be connected in series in the pull rod.

[0003] 2. Customized pin force sensors are required; different vehicle models require multiple different types of customized pin force sensors.

[0004] 3. The installation and debugging are complicated. A total of 3 tension and 3 angle sensors need to be connected. When the test is completed and the next vehicle is replaced for testing, it is necessary to re-adjust and recalibrate.

[0005] 4. The data processing is complex. The testers need to manually program and calculate the data obtained from the three tension and three angle sensors. Since matrix operations are involved, the testers are required to have a high level of data processing skills.

[0006] 5. Since the angle sensor can only convert the three force sensors to obtain the absolute horizontal direction, but the tractor is not in a horizontal state most of the time when it is working, the measured traction force has a large error. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a tractor traction force measuring device and method. During testing, simply attach the measuring device to the tractor, attach the agricultural implements to the measuring device, and then place the measuring host inside the vehicle to begin the test. The installation is simple and quick, and the actual tractor traction force can be obtained in real time, reducing the data processing workload of the test personnel and improving the measurement accuracy.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: a tractor traction force measuring device, comprising: Tractor side force transmission frame, used to connect the tractor; The side force transmission frame for agricultural implements is used to connect agricultural implements; An integrated traction force sensor, with its two ends fixedly connected to the tractor side force transmission frame and the implement side force transmission frame, respectively; After the measuring host is installed on the tractor, the coordinate system of the measuring host coincides with the coordinate system of the tractor. A GNSS antenna is mounted on the tractor and connected to the measurement host. The integrated traction force sensor includes a sensor body, an axial force measuring bridge, and a shear force measuring bridge. The axial force measuring bridge is arranged along the axis of the sensor body and is used to measure the tensile force along the axial direction. The shear force measuring bridge is arranged along the axis of the sensor body and is used to measure the shear force perpendicular to the axis. The sensor body is also equipped with a signal conditioning module, which is used to collect and process the signals from the axial force measuring bridge and the shear force measuring bridge to obtain the tensile force along the sensor axis and the shear force perpendicular to the sensor axis, as well as to acquire the attitude information of the integrated traction force sensor, and convert the tensile force and shear force into traction force in the geodetic coordinate system based on the attitude information. The measurement host is used to acquire the tractor's attitude information and convert the received traction force in the geodetic coordinate system from the signal conditioning module into the actual traction force in the tractor coordinate system.

[0009] Furthermore, both the tractor-side force transmission frame and the implement-side force transmission frame include a force transmission body and a shear groove and a calibration ring fixing groove disposed on the force transmission body; the calibration ring fixing groove is used to accommodate the calibration ring of the integrated traction force sensor and fix the calibration ring by a fastener to achieve axial positioning; the shear groove is used to engage with the end of the integrated traction force sensor to achieve circumferential positioning; the force transmission body is also provided with a mounting arm for connecting the tractor or implement.

[0010] Furthermore, the axial force measurement bridge includes a first axial force strain gauge, a second axial force strain gauge, a first axial force compensation strain gauge, and a second axial force compensation strain gauge disposed on the left and right sides of the sensor body; the first axial force strain gauge and the second axial force strain gauge are symmetrically installed, and the first axial force compensation strain gauge and the second axial force compensation strain gauge are symmetrically installed.

[0011] Furthermore, the shear force measurement bridge includes a first 45° shear strain gauge, a second 45° shear strain gauge, a first -45° shear strain gauge, and a second -45° shear strain gauge disposed on the left and right sides of the sensor body; the first 45° shear strain gauge and the second 45° shear strain gauge are symmetrically installed; the first -45° shear strain gauge and the second -45° shear strain gauge are symmetrically installed.

[0012] Furthermore, the signal conditioning module includes: a conditioning IMU chip, used to measure the triaxial acceleration and triaxial angular velocity of the sensor body in space in real time; The central processing unit analyzes the attitude and rotation matrix Cbn of the integrated traction force sensor based on the triaxial acceleration and triaxial angular velocity of the sensor body, and converts the tension and shear forces into traction forces in the geodetic coordinate system. The transceiver chip is used to send the rotation matrix Cbn and the traction force in the geodetic coordinate system to the measurement host.

[0013] Furthermore, the measurement host includes: a host IMU chip for acquiring the triaxial acceleration and triaxial angular velocity of the measurement host; The host central processing unit calculates the tractor's attitude and rotation matrix Cnb based on the measured three-axis acceleration and three-axis angular velocity of the host, and converts the traction force in the geodetic coordinate system into the actual traction force in the tractor coordinate system.

[0014] Furthermore, the host central processing unit is also used to read the tractor's vehicle status information through the OBD interface and CAN transceiver chip of the host measurement unit, and to obtain the tractor's position and speed information through the GNSS module of the host measurement unit, and to associate the vehicle status information, position and speed information with the actual traction force and store them in the memory of the host measurement unit.

[0015] The present invention also proposes a method for measuring tractor traction force, which uses the aforementioned tractor traction force measuring device and includes the following steps: The first step is to align the coordinate systems of the measuring host and the integrated traction sensor, and then perform attitude data fusion calibration after powering on to make the attitude data of the two consistent. The second step is to connect the two ends of the integrated traction sensor to the tractor and agricultural implements via the tractor side force transmission frame and the implement side force transmission frame, respectively. The third step involves the signal conditioning module measuring the tension F in the X direction using the axial force measurement full-bridge. x The shear force F in the Z direction was measured by shear force measurement of the entire bridge. z By adjusting the IMU chip to measure the triaxial acceleration and triaxial angular velocity of the sensor body in space, the attitude and rotation matrix Cbn of the integrated traction force sensor are calculated, and the tension F is then... x and shear force F z The tension F converted to the absolute horizontal direction in the geodetic coordinate system xh and the tension F pointing vertically towards the center of the earth zh ; Fourthly, the measuring host acquires the three-axis acceleration and three-axis angular velocity of the measuring host through the host IMU chip, calculates the tractor's attitude and rotation matrix Cnb, and then converts the received absolute horizontal tension F... xh and the tension F pointing vertically towards the center of the earth zhConverted into the actual forward traction force F of the tractor xt and downward traction force F zt .

[0016] Furthermore, before measurement, the axial force calibration coefficient of the integrated traction force sensor is obtained. The method for obtaining the coefficient is as follows: the two ends of the integrated traction force sensor are connected to the two ends of the tensile testing machine, and the tensile testing machine applies a gradually increasing tensile force along the axial direction of the sensor body until the preset target tensile force is reached. At the same time, the signal conditioning module records the axial force measurement voltage difference signal corresponding to each tensile force. Based on the multiple tensile force values ​​and their corresponding axial force measurement voltage difference signals, the axial force calibration coefficient of the integrated traction force sensor is calculated.

[0017] Furthermore, the shear calibration coefficient of the integrated traction force sensor is obtained before measurement. The method for obtaining the coefficient is as follows: the two ends of the integrated traction force sensor are connected to the upper and lower end faces of the shear force testing machine, respectively. The shear force is gradually increased by applying a shear force along the direction perpendicular to the axis of the sensor body through the shear force testing machine until the preset target shear force is reached. At the same time, the signal conditioning module records the shear force measurement voltage difference signal corresponding to each shear force. Based on the multiple shear force values ​​and their corresponding shear force measurement voltage difference signals, the shear force calibration coefficient of the integrated traction force sensor is calculated.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention uses an integrated traction force sensor to replace the dispersed upper tie rod sensor, lower tie rod pin sensor, and multiple angle sensors in the traditional solution. The sensor body integrates a full bridge for axial force and shear force measurement and a signal conditioning module, realizing synchronous in-situ acquisition of force and attitude information, eliminating the need for customized tie rods and multiple pin sensors, and greatly reducing the hardware complexity, manufacturing cost, and maintenance cost of the system.

[0019] 2. During testing, the device of this invention only needs to be connected in series between the tractor and the implement using a standardized force transmission frame, and the measuring host is fixed in the cab. After a simple system installation and calibration during the initial use, when testing with different tractor models, there is no need to repeatedly disassemble and reassemble multiple sensors or perform complex on-site calibration, truly achieving "install and test immediately." This solves the problems of cumbersome installation, long debugging cycle, and poor compatibility with different models in existing technologies, greatly improving testing efficiency.

[0020] 3. This invention, through a signal conditioning module and a measurement host, automatically completes the entire process from raw signal acquisition, calibration coefficient conversion, attitude fusion, two-level coordinate transformation to the final calculation of the actual traction force. Test personnel do not need to manually program and process multi-channel sensor signals, nor do they need to perform complex spatial matrix operations. The system runs automatically after startup, outputting results in real time, completely freeing test personnel from tedious data processing work and reducing reliance on the professional skills of the testing personnel.

[0021] 4. The measurement host in this invention not only processes traction force data, but also simultaneously collects vehicle operating parameters such as engine speed, fuel consumption, and gear position via the OBD / CAN bus, and obtains precise position, speed, and heading information through the GNSS module. The system associates and stores all data with a unified timestamp, achieving a strict one-to-one correspondence between traction force, vehicle status, and geographic information. This provides a complete and reliable data foundation for subsequent tractor performance analysis, operational quality assessment, and precision agriculture applications.

[0022] 5. This invention significantly improves measurement accuracy and reliability, reflecting real-world working conditions. First, the sensor body and strain gauges are made of nickel-chromium alloy with the same coefficient of thermal expansion, suppressing temperature drift at its source and ensuring long-term stability. Second, and most importantly, this invention creatively proposes a two-level coordinate transformation method. By separately measuring the real-time attitude of the sensor and the tractor body (rather than assuming they are in a horizontal state), the measured force values ​​are sequentially transformed to the geographic horizontal coordinate system and the tractor body coordinate system. This fundamentally eliminates measurement errors caused by the tilt of the tractor body and suspension mechanism when operating on slopes or uneven surfaces. Therefore, it can accurately measure the true tractor traction force that does not change with the vehicle body attitude, and the measurement results are closer to the actual force conditions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a tractor traction force testing device in the prior art; Figure 2 This is a schematic diagram of the tractor traction force measuring device in this invention; Figure 3 This is a schematic diagram of the tractor-side force transmission frame in this invention; Figure 4 This is a schematic diagram of the integrated traction force sensor in this invention; Figure 5 This is a schematic diagram of the signal conditioning module in this invention; Figure 6 This is a schematic diagram illustrating the connection method between the axial force measurement full-bridge and the signal conditioning module in this invention; Figure 7 This is a schematic diagram illustrating the connection method between the shear force measurement full-bridge and the signal conditioning module in this invention; Figure 8 This is a schematic diagram of the structure of the measuring host in this invention; Figure 9 This is a schematic diagram illustrating the acquisition of the actual load of the tractor in this invention; Markings in the diagram: 1. Tractor; 2. Agricultural implement; 3. Upper pull rod; 4. Right lower pull rod; 5. Left lower pull rod; 6. Upper pull rod tension / compression sensor; 7. Upper pull rod angle sensor; 8. Lower pull rod angle sensor; 9. Lower pull rod pin sensor; 10. Tractor side force transmission frame; 11. Agricultural implement side force transmission frame; 12. Integrated traction force sensor; 13. GNSS antenna; 14. Measurement host; 15. Tractor side mounting arm; 16. Force transmission body; 17. Shear groove; 18. Calibration ring fixing groove; 19. Fixing pin; 20. Sensor body; 21. First axial force strain gauge; 22. Second axial force strain gauge; 23. First axial force compensation strain gauge; 24. Second axial force compensation strain gauge; 25. First 45° shear force strain gauge; 26. Second 45° shear force strain gauge. 27. First -45° shear strain gauge; 28. Second -45° shear strain gauge; 29. ​​Signal conditioning module; 30. Tractor side calibration ring; 31. Implement side calibration ring; 32. Axial force strain connection terminal; 33. Shear strain connection terminal; 34. Amplifier circuit; 35. ADC acquisition chip; 36. Reference voltage unit; 37. Conditioning central processing unit; 38. Power supply unit; 39. Conditioning IMU chip; 40. Transceiver chip; 41. Output connection terminal; 42. Power supply connection terminal; 43. Input connection terminal; 44. OBD interface; 45. CAN transceiver chip; 46. Main unit central processing unit; 47. Main unit IMU chip; 48. GNSS antenna connection terminal; 49. GNSS module; 50. Grounding terminal. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the embodiments, but this should not be construed as limiting the invention in any way.

[0025] like Figure 2 As shown, the tractor traction force measuring device of the present invention includes a tractor-side force transmission frame 10, an implement-side force transmission frame 11, an integrated traction force sensor 12, a measuring host 14, and a GNSS antenna. The measuring host 14 has a coordinate system marked on its casing. After the measuring host 14 is installed on the tractor 1, it coincides with the tractor's coordinate system, i.e., the X-axis points in the tractor's forward direction, the Z-axis is vertically downwards perpendicular to the X-axis, and the Y-axis is perpendicular to the XZ plane and points to the right. The two ends of the integrated traction force sensor 12 are connected to the tractor-side force transmission frame 10 and the implement-side force transmission frame 11, respectively. The tractor-side force transmission frame 10 is connected to the tractor 1 being measured, and the implement-side force transmission frame 11 is connected to the implement 2 attached to the tractor 1.

[0026] The tractor side force transmission frame 10 and the implement side force transmission frame 11 have the same structure, which will be described below in conjunction with... Figure 3 Taking the tractor-side force transmission frame 10 as an example, its structural composition is described below. The tractor-side force transmission frame 10 mainly consists of a tractor-side mounting arm 15, a force transmission body 16, a shear groove 17, a calibration ring fixing groove 18, and a fixing pin 19, wherein the force transmission body 16 is the main part of its structure. The tractor-side mounting arm 15 is connected to the force transmission body 16, and there are three tractor-side mounting arms 15, which are respectively used to connect with the upper pull rod 3, the right lower pull rod 4, and the left lower pull rod 5 on the tractor 1. The force transmission body 16 is provided with a calibration ring fixing groove 18 and a fixing pin hole perpendicular to it, which is used to accommodate and lock the calibration ring at the end of the integrated traction force sensor 12. The shear groove 17 is opened on the side of the force transmission body 16, which is used to form a snap-fit ​​engagement with the end of the sensor body 20. During assembly, the tractor-side calibration rings 30 and implement-side calibration rings 31 at both ends of the integrated traction force sensor 12 are aligned with and inserted into the calibration ring fixing slots 18 on the tractor-side force transmission frame 10 and implement-side force transmission frame 11, respectively. Then, fixing pins 19 are inserted from the side into fixing pin holes to secure the tractor-side calibration rings 30 and implement-side calibration rings 31, preventing axial movement of the integrated traction force sensor 12. Simultaneously, the end of the integrated traction force sensor 12 can be engaged in the shear groove 17, effectively limiting the circumferential rotation of the integrated traction force sensor 12 caused by force during testing. Therefore, the main functions of the force transmission body 16 and the shear groove 17 are to balance the torque applied to the integrated traction force sensor by the tractor-side mounting arm 15, limit the relative displacement of the integrated traction force sensor 12 during testing, and transmit shear force to the integrated traction force sensor 12.

[0027] The integrated traction sensor 12 is the core measuring component of this device, and its structure is as follows: Figure 4 As shown, the sensor includes a sensor body 20, preferably made of a nickel-chromium alloy (80Ni-20Cr). Two sets of measuring full-bridges are disposed at specific locations on the surface of the sensor body 20: one for axial force measurement and the other for shear force measurement, both arranged along the sensor's axis. Furthermore, both the axial force and shear force measuring full-bridges are composed of strain gauges bonded to the surface of the sensor body 20.

[0028] Specifically, such as Figure 4As shown, in the axial force measurement full-bridge, the first axial force strain gauge 21 and the first axial force compensation strain gauge 23 are installed near the center of the right side surface of the sensor body 20, and the second axial force strain gauge 22 and the second axial force compensation strain gauge 24 are installed near the center of the left side surface of the sensor body 20. Furthermore, the first axial force strain gauge 21 and the second axial force strain gauge 22 are installed symmetrically, and the first axial force compensation strain gauge 23 and the second axial force compensation strain gauge 24 are installed symmetrically. The connection method between the axial force measurement full-bridge and the signal conditioning module 29 is as follows: Figure 6 As shown: After the current exits the reference voltage unit 36, it splits into two paths. One path passes through the first axial force strain gauge 21 and the second axial force compensation strain gauge 24, returning to the ground terminal 50. The other path passes through the first axial force compensation strain gauge 23 and the second axial force strain gauge 22, returning to the ground terminal 50. One end of the axial force strain gauge connection terminal 32 is connected between the first axial force strain gauge 21 and the second axial force compensation strain gauge 24, and the other end is connected between the first axial force compensation strain gauge 23 and the second axial force strain gauge 22. The voltage difference between the two ends can be collected. After the voltage difference is amplified by the amplifier circuit 34, it enters the ADC acquisition chip 35 for sampling and is finally transmitted to the conditioning central processing unit 37. The conditioning central processing unit 37 multiplies the voltage difference by the axial force calibration coefficient to obtain the tensile force F. x .

[0029] Continue to refer to Figure 4 As shown, for the shear force measurement full-bridge, the first 45° shear strain gauge 25 and the first -45° shear strain gauge 27 are installed on the right side surface of the sensor body 20 near both ends, and the second 45° shear strain gauge 26 and the second -45° shear strain gauge 28 are installed on the left side surface of the sensor body near both ends. During installation, the first 45° shear strain gauge 25 and the second 45° shear strain gauge 26 are installed symmetrically; the first -45° shear strain gauge 27 and the second -45° shear strain gauge 28 are installed symmetrically. The connection method between the shear force measurement full-bridge and the signal conditioning module 29 is as follows: Figure 7 As shown: After the current exits the reference voltage unit 36, it splits into two paths. One path returns to the ground terminal 50 via the first 45° shear strain gauge 25 and the second -45° shear strain gauge 28; the other path returns to the ground terminal 50 via the first -45° shear strain gauge 27 and the second 45° shear strain gauge 26. One end of the shear strain connection terminal 33 is connected between the first 45° shear strain gauge 25 and the second -45° shear strain gauge 28, and the other end is connected between the first -45° shear strain gauge 27 and the second 45° shear strain gauge 26. The voltage difference between the two ends can be collected. After the voltage difference is amplified by the amplifier circuit 34, it enters the ADC acquisition chip 35 for sampling and is finally transmitted to the conditioning central processing unit 37. The conditioning central processing unit 37 multiplies the voltage difference by the shear force calibration coefficient to obtain the shear force F. z .

[0030] All strain gauges are preferably made of nickel-chromium alloy to ensure that their coefficient of thermal expansion is consistent with that of the sensor body 20, thereby eliminating the influence of ambient temperature changes on measurement accuracy.

[0031] In this invention, the integrated traction sensor 12 integrates a signal conditioning module 29. For example... Figure 5 As shown, the signal conditioning module 29 includes an axial strain connection terminal 32, a shear strain connection terminal 33, an amplifier circuit 34, an ADC acquisition chip 35, a reference voltage unit 36, a conditioning central processing unit 37, a power supply unit 38, a conditioning IMU chip 39, a transceiver chip 40, an output connection terminal 41, and a power supply connection terminal 42. The conditioning IMU chip 39 serves as the first attitude measurement unit, used to measure the triaxial acceleration and triaxial angular velocity of the sensor body 20 in space in real time, and transmits the signals to the conditioning central processing unit 37 to analyze the attitude and rotation matrix of the integrated traction sensor 12. A coordinate system is marked on the outer casing of the signal conditioning module 29, and the definition of the coordinate system is as follows: Figure 4 As shown, its X-axis is parallel to the sensor axis and points in the direction of the tractor's forward movement (i.e., the direction of traction force), its Z-axis is perpendicular to the X-axis and points vertically downward, and its Y-axis is perpendicular to the XZ plane and points to the right.

[0032] In this invention, the structure of the measuring host 14 is as follows: Figure 8 As shown, the system includes a power supply unit 38, a transceiver chip 40, a power supply connection terminal 42, an input connection terminal 43, an OBD interface 44, a CAN transceiver chip 45, a host central processing unit 46, a host IMU chip 47, a GNSS antenna connection terminal 48, and a GNSS module 49. The host IMU chip 47 serves as a second attitude measurement unit, used to measure the tractor's attitude (i.e., three-axis acceleration and three-axis angular velocity) in real time after installation. The GNSS module 49 receives satellite signals and analyzes the tractor's real-time position, speed, and heading information. The OBD interface 44 and the CAN transceiver chip 45 are used to access the tractor's onboard network and read vehicle status parameters such as engine speed, fuel consumption, throttle opening, and gear position.

[0033] This embodiment provides a method for measuring tractor traction force. The method uses the measuring device described in Embodiment 1 and converts the force value directly measured by the sensor into the actual traction force in the tractor body coordinate system through two-level coordinate transformation.

[0034] Before measuring the tractor traction force, the axial force calibration coefficient and shear force calibration coefficient of the integrated traction force sensor 12 should be calibrated in advance, and only need to be calibrated once before leaving the factory. The calibration coefficients are stored in the signal conditioning module 29 and are subsequently used to obtain the axial force and shear force.

[0035] The method for obtaining the axial force calibration coefficient of the integrated traction sensor 12 is as follows: Step 1: Power on the signal conditioning module 29 and power on the integrated traction sensor 12 in a free state.

[0036] Step 2: Connect the tractor-side calibration ring 30 and implement-side calibration ring 31 in the integrated traction sensor 12 to both ends of the tensile testing machine.

[0037] Step 3: Apply a tensile force every 500N until the tensile force reaches 8000N, and read the axial force measurement voltage difference corresponding to each force. Use the force / axial force measurement voltage difference to obtain the axial force calibration coefficient.

[0038] The method for obtaining the shear force calibration coefficient of the integrated traction force sensor 12 is as follows: Step 1: Power on the signal conditioning module 29 and power on the integrated traction sensor 12 in a free state.

[0039] Step 2: Connect the tractor-side calibration ring 30 and implement-side calibration ring 31 in the integrated traction force sensor 12 to the upper and lower end faces of the shear force testing machine.

[0040] Step 3: Apply a tensile force every 500N until the tensile force reaches 8000N, and read the shear force measurement voltage difference corresponding to each force. Use the force / shear force measurement voltage difference to obtain the shear force calibration coefficient.

[0041] After the integrated traction sensor 12 is calibrated, the traction force of the tractor is measured using the measuring device of Embodiment 1. The specific steps are as follows: Step 1: Place the measuring host 14 on the top surface of the integrated traction sensor 12, so that the X, Y, and Z axes on the measuring host 14 coincide with the X, Y, and Z axes on the signal conditioning module 29.

[0042] Step two: Power on the measurement host 14 and signal conditioning module 29, enter the system and select "Installation and Calibration". At this time, the conditioning IMU chip 39 on the signal conditioning module 29 will measure the acceleration and angular velocity on the three coordinate axes of the integrated traction sensor 12, and transmit the signals to the conditioning central processing unit 37 to analyze the attitude and rotation matrix of the integrated traction sensor 12. The rotation matrix data is sent to the input connection terminal 43 of the measurement host 14 through the transceiver chip 40 and the output connection terminal 41 of the signal conditioning module 29, and then enters the host central processing unit 46 through the transceiver chip 40 of the measurement host 14. The host central processing unit 46 will predict the X, Y, and Z axis accelerations of the measurement host 14 based on the transmitted rotation matrix data. The host central processing unit 46 also collects the acceleration and angular velocity on the three coordinate axes of the measurement host 14 through the host IMU chip 47, and fuses the collected three accelerations with the predicted three axis accelerations, and saves the error data to the memory in the host central processing unit 46, so that the signal conditioning module 29 and the measurement host 14 have the same attitude data, and completes the installation and calibration of the system.

[0043] Step 3, according to Figure 2-4 As shown, the upper pull rod 3, right lower pull rod 4, and left lower pull rod 5 of tractor 1 are connected to the tractor side attachment arm 15 in the tractor side force transmission frame 10. The attachment arm of agricultural implement 2 is connected to the agricultural implement side force transmission frame 11.

[0044] The tractor-side calibration ring 30 and implement-side calibration ring 31 of the integrated traction force sensor 12 are inserted into the calibration ring fixing grooves 18 in the tractor-side force transmission frame 10 and implement-side force transmission frame 11, respectively, and fixed with fixing pins 19.

[0045] The measuring host 14 is securely fixed inside the tractor 1, and no relative movement of the measuring host 14 is permitted during testing. After installation, the coordinate system of the measuring host 14 coincides with the coordinate system of the tractor 1, i.e., the X-axis points in the direction of vehicle movement, the Z-axis is vertically downwards perpendicular to the X-axis, and the Y-axis is perpendicular to the XZ plane and points to the right. Finally, the GNSS antenna 12 is connected to the GNSS antenna connection terminal 48 of the measuring host 14 to complete the installation of the equipment.

[0046] Step four, as Figure 9 As shown, after the test begins, the conditioning central processing unit 37 in the signal conditioning module 29 measures the tension along the sensor axis, i.e., the tension F in the X direction, from the axial force measuring bridge. x The shear force perpendicular to the axis, i.e., the shear force F in the Z direction, is measured from the shear force measurement of the entire bridge. zThe conditioning central processing unit 37 acquires three accelerations and three angular velocities on the three coordinate axes of the integrated traction sensor 12 from the conditioning IMU chip 39, and fuses them using a Kalman filter algorithm to obtain the attitude and rotation matrix Cbn of the integrated traction sensor 12 (representing the rotation from the sensor coordinate system to the ground coordinate system). Then, the conditioning central processing unit 37 processes the measured axial force F... x and shear force F z Multiplying by the rotation matrix Cbn yields the tension F in the absolute horizontal direction. xh and the tension F pointing vertically towards the center of the earth zh The conditioning central processing unit 37 will process the calculated rotation matrix Cbn and tension F. xh Tension F zh The data is transmitted to the measurement host 14 via the transceiver chip 40 and the output connection terminal 41.

[0047] Step 5, as Figure 9 As shown, the measuring host 14 receives the tension F in the absolute horizontal direction through the input connection terminal 43 and the transceiver chip 40. xh A pulling force F perpendicular to the center of the earth zh The central processing unit 46 collects the three accelerations and three angular velocities on the three coordinate axes of the main unit 14 from the main unit IMU chip 47, and calculates the attitude and rotation matrix of the main unit 14, that is, the attitude and rotation matrix Cnb of the tractor 1 (representing the rotation from the geodetic coordinate system to the tractor coordinate system). The central processing unit 46 then processes the pulling force F... xh Tension F zh Multiplying the force by the rotation matrix Cnb allows you to calculate the actual forward traction force F of the tractor. xt and downward traction force F zt .

[0048] Step six: The measurement host 14 reads the vehicle's speed, fuel consumption, throttle opening, and gear signal through the OBD interface 44 and CAN transceiver chip 45, and extracts the tractor 1's actual speed, heading angle, and position from the GNSS module 49, and packages the forward traction force F. xt and downward traction force F zt The data is stored together in the built-in memory, which enables a one-to-one correspondence between traction force and vehicle status, allowing test personnel to view the actual traction force data at any time.

[0049] In the above-mentioned Cbn, "b" represents the Body Frame, which in this case refers to the coordinate system of the integrated traction sensor 12, and also the coordinate system of the conditioning module 29; "n" represents the Navigation Frame, i.e., the geodetic coordinate system; therefore, the rotation matrix Cbn is used to represent the rotation from the sensor coordinate system to the geodetic coordinate system. In the above-mentioned Cnb, "b" refers to the coordinate system of the measuring host 14, i.e., the tractor's coordinate system; therefore, the rotation matrix Cnb is used to represent the rotation from the geodetic coordinate system to the tractor's coordinate system.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the specific implementation of the present invention with reference to the above embodiments. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the protection scope of the pending claims.

Claims

1. A tractor traction force measuring device, characterized in that, include: Tractor side force transmission frame (10) is used to connect the tractor; The implement side force transmission frame (11) is used to connect agricultural implements; An integrated traction force sensor (12) is fixedly connected at both ends to the tractor side force transmission frame (10) and the implement side force transmission frame (11), respectively. After the measuring host (14) is installed on the tractor (1), the coordinate system of the measuring host (14) coincides with the coordinate system of the tractor; A GNSS antenna (13) is mounted on the tractor (1) and connected to the measurement host (14); The integrated traction sensor (12) includes a sensor body (20) and an axial force measuring bridge and a shear force measuring bridge. The axial force measuring bridge is arranged along the axis of the sensor body (20) and is used to measure the tensile force along the axial direction. The shear force measuring bridge is arranged along the axis of the sensor body (20) and is used to measure the shear force perpendicular to the axis. The sensor body (20) is also provided with a signal conditioning module (29). The signal conditioning module (29) is used to collect and process the signals of the axial force measuring bridge and the shear force measuring bridge to obtain the tensile force along the sensor axis and the shear force perpendicular to the sensor axis, as well as to obtain the attitude information of the integrated traction sensor (12) and convert the tensile force and shear force into traction force in the geodetic coordinate system based on the attitude information. The measurement host (14) is used to acquire the attitude information of the tractor (1) and convert the traction force received from the signal conditioning module (29) in the geodetic coordinate system into the actual traction force in the tractor coordinate system.

2. The tractor traction force measuring device according to claim 1, characterized in that, Both the tractor-side force transmission frame (10) and the implement-side force transmission frame (11) include a force transmission body (16) and a shear groove (17) and a calibration ring fixing groove (18) provided on the force transmission body (16); the calibration ring fixing groove (18) is used to accommodate the calibration ring of the integrated traction force sensor (20) and fix the calibration ring by a fastener to achieve axial positioning; the shear groove (17) is used to engage with the end of the integrated traction force sensor (12) to achieve circumferential positioning; the force transmission body (16) is also provided with a hook arm for connecting the tractor (1) or the implement (2).

3. The tractor traction force measuring device according to claim 1, characterized in that, The axial force measurement bridge includes a first axial force strain gauge (21), a second axial force strain gauge (22), a first axial force compensation strain gauge (23), and a second axial force compensation strain gauge (24) disposed on the left and right sides of the sensor body (20); the first axial force strain gauge (21) and the second axial force strain gauge (22) are symmetrically installed, and the first axial force compensation strain gauge (23) and the second axial force compensation strain gauge (24) are symmetrically installed.

4. The tractor traction force measuring device according to claim 1, characterized in that, The shear force measurement bridge includes a first 45° shear strain gauge (25), a second 45° shear strain gauge (26), a first -45° shear strain gauge (27), and a second -45° shear strain gauge (28) disposed on the left and right sides of the sensor body (20); the first 45° shear strain gauge (25) and the second 45° shear strain gauge (26) are symmetrically installed; the first -45° shear strain gauge (27) and the second -45° shear strain gauge (28) are symmetrically installed.

5. The tractor traction force measuring device according to claim 1, characterized in that, The signal conditioning module (29) includes: a conditioning IMU chip (39) for real-time measurement of the triaxial acceleration and triaxial angular velocity of the sensor body (20) in space; The central processing unit (37) analyzes the attitude and rotation matrix Cbn of the integrated traction force sensor (12) based on the triaxial acceleration and triaxial angular velocity of the sensor body (20), and converts the tension and shear forces into traction forces in the geodetic coordinate system. A transceiver chip (40) is used to send the rotation matrix Cbn and the traction force in the geodetic coordinate system to the measurement host (14).

6. The tractor traction force measuring device according to claim 1, characterized in that, The measurement host (14) includes: a host IMU chip (47) for acquiring the triaxial acceleration and triaxial angular velocity of the measurement host (14); The host central processing unit (46) calculates the attitude and rotation matrix Cnb of the tractor (1) based on the three-axis acceleration and three-axis angular velocity of the host (14), and converts the traction force in the geodetic coordinate system into the actual traction force in the tractor coordinate system.

7. The tractor traction force measuring device according to claim 6, characterized in that, The host central processing unit (46) is also used to read the vehicle status information of the tractor (1) through the OBD interface (44) and CAN transceiver chip (45) of the host (14), and to obtain the position and speed information of the tractor (1) through the GNSS module (49) of the host (14), and to associate the vehicle status information, position and speed information with the actual traction force and store them in the memory of the host (14).

8. A method for measuring tractor traction force, characterized in that, This method uses the tractor traction force measuring device according to any one of claims 1-7, and includes the following steps: The first step is to align the coordinate systems of the measuring host (14) and the integrated traction sensor (12), and perform attitude data fusion calibration after powering on to make the attitude data of the two consistent. The second step is to connect the two ends of the integrated traction sensor (12) to the tractor (1) and the agricultural implement (2) respectively through the tractor side transmission frame (10) and the agricultural implement side transmission frame (11); The third step is for the signal conditioning module (29) to measure the tension F in the X direction using the axial force measurement bridge. x The shear force F in the Z direction was measured by shear force measurement of the entire bridge. z ; and by conditioning the IMU chip (39) to measure the triaxial acceleration and triaxial angular velocity of the sensor body (20) in space, the attitude and rotation matrix Cbn of the integrated traction sensor (12) are calculated, and the tension F is calculated. x and shear force F z The tension F converted to the absolute horizontal direction in the geodetic coordinate system xh and the tension F pointing vertically towards the center of the earth zh ; In the fourth step, the measuring host (14) acquires the triaxial acceleration and triaxial angular velocity of the measuring host (14) through the host IMU chip (47), and calculates the attitude and rotation matrix Cnb of the tractor (1), and then transmits the received absolute horizontal tension F xh and the tension F pointing vertically towards the center of the earth zh Converted into the actual forward traction force F of the tractor xt and downward traction force F zt .

9. The tractor traction force measurement method according to claim 1, characterized in that, Before measurement, the axial force calibration coefficient of the integrated traction force sensor (12) is obtained. The method for obtaining the coefficient is as follows: the two ends of the integrated traction force sensor (12) are connected to the two ends of the tensile testing machine respectively. The tensile testing machine applies a gradually increasing tensile force along the axial direction of the sensor body (20) until the preset target tensile force is reached. At the same time, the signal conditioning module (29) records the axial force measurement voltage difference signal corresponding to each tensile force. Based on the multiple tensile force values ​​and their corresponding axial force measurement voltage difference signals, the axial force calibration coefficient of the integrated traction force sensor (12) is calculated.

10. The tractor traction force measurement method according to claim 1, characterized in that, Before measurement, the shear calibration coefficient of the integrated traction force sensor (12) is obtained. The method for obtaining the coefficient is as follows: the two ends of the integrated traction force sensor (12) are connected to the upper and lower end faces of the shear force testing machine, respectively. The shear force is gradually increased by applying the shear force along the direction perpendicular to the axis of the sensor body (20) until the preset target shear force is reached. At the same time, the signal conditioning module (29) records the shear force measurement voltage difference signal corresponding to each shear force. Based on the multiple shear force values ​​and their corresponding shear force measurement voltage difference signals, the shear calibration coefficient of the integrated traction force sensor (12) is calculated.

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