Wheel loader operation load spectrum analysis method and system

Abstract

The invention provides a wheel loader operation load spectrum analysis method and system, and relates to the field of loader design, and the method comprises the steps: S1, obtaining the extension of a tipping bucket cylinder, the extension of a movable arm cylinder, the pressure of the tipping bucket cylinder, the pressure of the movable arm cylinder, the rotating speed of a motor, and the torque of the motor; s2, the mass center position, the rotation angle and the hinge point position of each component of the working device of the wheel loader are calculated; s3, calculating the vehicle speed and the traction force of the whole vehicle; s4, when the pressure of the tipping bucket cylinder exceeds a set threshold value, the acting force of the tipping bucket cylinder is corrected; and S5, constructing a dynamic algorithm model, calculating the acting force of each hinged part in the operation process and the operation load acting on the bucket, and obtaining an operation load spectrum based on the operation load. On the premise of not obviously increasing the test cost, the loading machine operation load spectrum can be conveniently and accurately obtained, and the method can be applied to analysis and evaluation of the loading machine structure reliability.

Description

Technical Field

[0001] The present invention relates to the field of loader design, and in particular to a method and system for analyzing an operating load spectrum of a wheel loader. Background Art

[0002] The reliability of loader working devices has long been a concern of manufacturers and users. The premise for calculating its reliability is to obtain the stress conditions of each component during operation, that is, the operating load spectrum.

[0003] Conventional technology uses a pin sensor to measure the pin force at a specific hinge location, then calculates the pin forces at other hinge locations based on force and torque balance relationships. Pin sensors must be customized based on the pin type of the test vehicle, making them difficult to reuse on other models. Furthermore, the installation process is time-consuming and labor-intensive, and the equipment is expensive, resulting in high testing costs.

[0004] In addition, existing techniques use rigid-discrete co-simulation to capture the forces acting on a loader during operation. This involves installing displacement sensors on the actual vehicle to measure the hydraulic cylinder's motion and collecting vehicle location information using GPS. This data is then fed into a co-simulation model to drive the movement of a virtual loader model, allowing the software to extract the pin forces at each articulated joint during operation. The difficulty with this method lies in the need to calibrate the stockpile for different operating environments.

[0005] In summary, a new force calculation method needs to be provided to solve the above problems. Summary of the Invention

[0006] In order to address the deficiencies of the above-mentioned prior art, the present invention provides a method and system for analyzing the operating load spectrum of a wheel loader, which can conveniently and accurately obtain the operating load spectrum of the loader without increasing the testing cost, and analyze the reliability of the loader structure based on the operating load spectrum.

[0007] To achieve the above objectives, the present invention discloses the following technical solutions:

[0008] In a first aspect, the present invention provides a method for analyzing an operating load spectrum of a wheel loader, comprising:

[0009] S1. Obtain the bucket cylinder extension, boom cylinder extension, bucket cylinder pressure, boom cylinder pressure, motor speed, and motor torque;

[0010] S2. Based on the kinematic model of the loader's working linkage mechanism and the acquired bucket cylinder extensions and boom cylinder extensions, calculate the center of mass position and rotation angle of each component of the wheel loader's working device, as well as the positions of each hinge point;

[0011] S3. Obtain tire size and calculate vehicle speed and vehicle traction based on motor speed and motor torque;

[0012] S4. Calculate the bucket cylinder force and the boom cylinder force based on the bucket cylinder pressure and the boom cylinder pressure. When the bucket cylinder pressure exceeds the set threshold, correct the bucket cylinder force:

[0013]

[0014] Among them, F FDG is the force of the modified dump cylinder, m i is the mass of component i; g is the acceleration due to gravity; L mi is the horizontal distance between the center of mass of component i and the hinge position between the boom and the front frame; L1 is the force arm of the boom cylinder force at the hinge position between the boom and the front frame; L2 is the horizontal distance between the center of mass of the load and the hinge position between the boom and the front frame; L3 is the force arm of the dump cylinder force at the hinge position between the boom and the front frame; r is the force transmission ratio of the dump mechanism; F DBG is the force of the boom cylinder.

[0015] S5. Construct a dynamic algorithm model and input the calculated center of mass position and rotation angle of each component of the working device, vehicle speed, vehicle traction, bucket cylinder force, and boom cylinder force into the dynamic algorithm model. Calculate the forces acting at each articulation during the operation and the operating load acting on the bucket, and obtain the operating load spectrum based on the operating load.

[0016] Preferably, the method for obtaining the tire size in step S3 specifically includes the following sub-steps: S31, measuring the bridge loads of the front drive axle and the rear drive axle and the corresponding tire radius using a fixed mass weight, and obtaining the tire size under multiple sets of bridge load data;

[0017] S32. Based on the center of mass positions of the various components of the working device and the entire vehicle as the research object, the bridge loads of the front drive axle and the rear drive axle are calculated according to the force balance and torque balance relationships; S33. Based on the calculated bridge loads of the front drive axle and the rear drive axle, the tire size is obtained by interpolation.

[0018] Preferably, step S3 specifically includes the following sub-steps: In step S32, the equations for solving the bridge loads of the front drive axle and the rear drive axle are as follows:

[0019]

[0020] Where mi is the mass of component i; Ff and Fr are the bridge loads of the front drive axle and rear drive axle respectively; Li_r is the horizontal distance from the center of mass of component i to the rear drive axle; Lf_r is the horizontal distance from the front drive axle to the rear drive axle.

[0021] Preferably, step S3 specifically includes the following sub-steps: The method for obtaining the tire size by interpolation in step S33 is as follows:

[0022]

[0023] Where Rf and Rr are the tire sizes of the front drive axle and rear drive axle respectively; Qiaohe Front drive axle tire size below; Qiaohe The rear drive axle tire size is as follows.

[0024] Preferably, step S5 specifically includes the following sub-steps:

[0025] S51, calculating the translational acceleration and rotational angular acceleration of each component based on the component's center of mass position, rotation angle, and vehicle speed;

[0026] S52. Constructing a dynamic algorithm model based on the Newton-Euler method according to the connection relationship between the components;

[0027] S53. Solve the dynamic algorithm model to obtain the forces acting on each hinge during the operation and the operating load acting on the bucket.

[0028] Preferably, the dynamic algorithm model constructed in step S52 is specifically:

[0029] AX=B

[0030] Where A is:

[0031]

[0032] Where n is the number of components, m is the number of hinges, the submatrix aij represents the contribution of the force at the j-th hinge to the force balance and moment balance of the i-th component, and the submatrix ai(m+1) represents the contribution of the operating load to the force balance and moment balance of the i-th component;

[0033] In the dynamics algorithm model, X is:

[0034]

[0035] Where, F Mj_x 、F Mj_y represents the force at the hinge point Mj; Fx, Fy, and Tz are the operating loads acting on the bucket;

[0036] In the dynamics algorithm model, B is:

[0037] B=B inertial +B external

[0038] Among them, Binertial is the inertia force matrix; Bextermal is the matrix composed of known external forces such as the bucket cylinder force and the boom cylinder force.

[0039] Preferably, when the extension of the dump cylinder and the boom cylinder cannot be obtained, the boom angle sensor and the rocker arm angle sensor are used to collect the rotation angle of the boom relative to the front frame and the rotation angle of the rocker arm relative to the boom, and based on the motion model of the loader working linkage mechanism, the center of mass position and rotation angle of each component of the working device of the wheel loader and the position of each hinge point are calculated.

[0040] Preferably, in step S1 , the elongation of the bucket cylinder, the elongation of the boom cylinder, the pressure of the bucket cylinder, and the pressure of the boom cylinder are acquired through CAN acquisition, and the motor speed and the motor torque are measured by sensors.

[0041] In a second aspect, the present invention provides a wheel loader reliability analysis system for a wheel loader operating load spectrum analysis method, which includes: a data acquisition module for obtaining the elongation of the bucket cylinder, the elongation of the boom cylinder, the bucket cylinder pressure, the boom cylinder pressure, the motor speed and the motor torque; a kinematic calculation module for calculating the center of mass position and rotation angle of each component of the working device and the position of each hinge point; a tire size calculation module for calculating the tire size by an interpolation method; a bucket cylinder force correction module for correcting the bucket cylinder force; and a dynamics calculation module for calculating the force at each hinge during the operation and the operating load acting on the bucket, that is, the operating load spectrum.

[0042] Preferably, a storage module is further included to store the operation load spectra of different loaders to obtain an operation load spectrum database for subsequent analysis.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The wheel loader operating load spectrum analysis method of the present invention obtains the wheel loader operating load spectrum by obtaining the bucket cylinder extension, boom cylinder extension, bucket cylinder pressure, boom cylinder pressure, motor speed and motor torque in combination with a dynamic model. Based on existing measurement means, the loader operating load spectrum can be conveniently and accurately obtained without significantly increasing the test cost. It can be applied to the analysis and evaluation of the loader structure reliability or other applications.

[0045] (2) The wheel loader operating load spectrum analysis method of the present invention calculates the bucket cylinder force and the boom cylinder force based on the bucket cylinder pressure and the boom cylinder pressure. When the bucket cylinder pressure exceeds a set threshold, the bucket cylinder force is corrected to ensure the accuracy of the final result.

[0046] (3) The present invention provides a wheel loader operating load spectrum analysis system, which can calculate the forces acting on each articulation during the operation and the operating load acting on the bucket through a dynamic calculation module, that is, the operating load spectrum, thereby increasing the engineering application of the operating load spectrum. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Schematic diagram of a method for analyzing a wheel loader operating load spectrum according to an embodiment of the present invention;

[0048] Figure 2 A schematic diagram of a wheel loader operating load spectrum calculation system according to an embodiment of the present invention;

[0049] Figure 3 A schematic diagram of a working linkage mechanism of a loader according to an embodiment of the present invention;

[0050] Figure 4 This is a comparison chart of the calculation results of the operating load spectrum method of the present invention and the test results of the pin sensor;

[0051] Figure 5 The second figure compares the calculation results of the operating load spectrum method of the present invention with the test results of the pin shaft sensor. DETAILED DESCRIPTION

[0052] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0053] In one aspect, the present invention provides a method for analyzing a wheel loader operating load spectrum, comprising the following steps:

[0054] S1. Obtain the bucket cylinder extension, boom cylinder extension, bucket cylinder pressure, boom cylinder pressure, motor speed, and motor torque. The bucket cylinder extension, boom cylinder extension, bucket cylinder pressure, and boom cylinder pressure are measured by sensors, and the motor speed and motor torque are collected via CAN.

[0055] S2. Based on the kinematic model of the loader's working linkage mechanism and the acquired bucket cylinder and boom cylinder extensions, calculate the center of mass and rotation angles of each working device component, as well as the locations of each hinge point. The hinge point locations can be determined by constructing a kinematic model of the linkage mechanism. Specifically, the following steps are included:

[0056] S21, according to Figure 3 The schematic diagram of the loader working linkage mechanism is shown in Figure 1, with the length of the bucket cylinder L EG and boom cylinder length L FH As input, calculate the rotation angle θ1 of the boom relative to the frame, the rotation angle θ2 of the rocker arm relative to the boom, the rotation angle θ3 of the drawbar relative to the rocker arm, and the rotation angle θ4 of the bucket relative to the boom:

[0057]

[0058] θ1=∠FIH-∠FIH init

[0059] ∠DIG=∠DIG init +θ1

[0060]

[0061] ∠EDI=∠EDG+∠GDI

[0062] ∠ADC=∠ADI-∠CDE+∠EDI

[0063] θ2=∠ADC-∠ADC init

[0064]

[0065] ∠BAD=∠BAC-∠CAD

[0066]

[0067] θ3=∠BCD-∠BCD init

[0068] ∠BAF=∠BAD+∠DAF

[0069] θ4=∠BAF-∠BAF init +θ1.

[0070] S22. Based on the calculated boom-to-frame rotation angle θ1, rocker arm rotation angle θ2, drawbar rotation angle θ3, and bucket rotation angle θ4, the center of mass and hinge positions of the various components of the working device are calculated using the DH method. Take the calculation of the coordinates of the articulation center A between the bucket and boom as an example:

[0071]

[0072] Where, They are the initial coordinates of the articulation center A between the bucket and the boom, and the intersection center I between the boom and the frame.

[0073] S3. Obtain tire size and, combined with motor speed and motor torque, calculate vehicle speed and vehicle traction. Vehicle speed is equal to the product of motor speed and tire size. Vehicle traction is equal to the sum of the traction of each drive wheel. The traction of each drive wheel is equal to the product of its motor torque and tire size. The tire size acquisition method specifically includes the following sub-steps:

[0074] S31. Measure the axle loads and corresponding tire radii of the front and rear drive axles using a fixed-mass weight block to obtain tire dimensions under multiple sets of axle load data.

[0075] S32. Based on the center of mass position of each component of the working device and the entire vehicle as the research object, the following equations are written based on the force balance and torque balance relationships. By solving these equations, the bridge loads of the front and rear drive axles are obtained:

[0076]

[0077] Where m i is the mass of component i; F f 、F r are the bridge loads of the front drive axle and the rear drive axle respectively; L i_r L is the horizontal distance from the center of mass of component i to the rear drive axle; f_r It is the horizontal distance from the front drive axle to the rear drive axle.

[0078] S33. Based on the calculated axle loads of the front drive axle and the rear drive axle, the tire size is obtained by interpolation:

[0079]

[0080] Where R f 、R r These are the tire sizes for the front and rear drive axles respectively; Qiaohe For the tire size of the front drive axle below; Qiaohe For the rear drive axle tire size below.

[0081] S4. Calculate the bucket cylinder force and the boom cylinder force based on the bucket cylinder pressure and the boom cylinder pressure. When the bucket cylinder pressure exceeds the set threshold, correct the bucket cylinder force:

[0082]

[0083] Among them, F FDG is the force acting on the rear dump cylinder, m i is the mass of component i; g is the acceleration due to gravity; L mi is the horizontal distance between the center of mass of component i and the hinge position between the boom and the front frame; L1 is the force arm of the boom cylinder force at the hinge position between the boom and the front frame; L2 is the horizontal distance between the center of mass of the load and the hinge position between the boom and the front frame; L3 is the force arm of the dump cylinder force at the hinge position between the boom and the front frame; r is the force transmission ratio of the dump mechanism; F DBG is the force of the boom cylinder. The threshold is generally determined based on historical data.

[0084] S5. Construct a dynamic algorithm model and input the calculated center of mass position and rotation angle of each component of the working device, vehicle speed, vehicle traction, bucket cylinder force, and boom cylinder force into the dynamic algorithm model. Calculate the forces acting at each articulation during the operation and the operating load acting on the bucket, and obtain the operating load spectrum based on the operating load.

[0085] Step S5 specifically includes the following sub-steps:

[0086] S51. Calculate the translational acceleration and rotational angular acceleration of each component according to the component's center of mass position, rotation angle, and vehicle speed.

[0087] S52, constructing a dynamic algorithm model based on the Newton-Euler method according to the connection relationship between the components. The dynamic algorithm model constructed in step S52 is specifically:

[0088] AX=B

[0089] Where A is:

[0090]

[0091] Where n is the number of components, m is the number of hinge points, and submatrix a ij Represents the contribution of the force at the j-th joint to the force balance and moment balance of the i-th component, submatrix a i(m+1) It represents the contribution of the operating load to the force balance and moment balance of the i-th component.

[0092] In the dynamics algorithm model, X is:

[0093]

[0094] Where, F Mj_x 、F Mj_y Represents the hinge point M j The force at x 、F y 、T z is the operating load acting on the bucket.

[0095] In the dynamics algorithm model, B is:

[0096] B=B inertial +B external

[0097] Among them, B inertial is the inertia force matrix; B extermal It is a matrix composed of known external forces such as the bucket cylinder force and the boom cylinder force.

[0098] S53. By solving the dynamic algorithm model, the forces acting on each joint and the operating load acting on the bucket during the operation are obtained. Based on the obtained operating load, an operating load spectrum is obtained and used for subsequent analysis.

[0099] In other embodiments, the obtained operation load spectrum may be stored to obtain an operation load spectrum database for subsequent analysis. For example, the operation load spectrum database may be used to extract the operation load spectrum to analyze the structural reliability of various components of the loader.

[0100] This embodiment provides a method for analyzing the load spectrum of a wheel loader operation. The flow chart is as follows: Figure 1 Specifically, the wheel loader operation load spectrum analysis method includes the following steps:

[0101] S1. Obtaining the bucket cylinder extension, boom cylinder extension, bucket cylinder pressure, boom cylinder pressure, motor speed, and motor torque. In this embodiment, sensors measure the bucket cylinder extension, boom cylinder extension, bucket cylinder pressure, boom cylinder pressure, motor speed, and motor torque, respectively, and store them.

[0102] S2. Based on the kinematic model of the loader's working linkage, calculate the center of mass, rotation angle, and hinge locations of each working device component based on the bucket cylinder and boom cylinder extensions. Construct a kinematic model of the loader's working linkage, calculate the center of mass, rotation angle, and hinge locations of each working device component, and save the results for subsequent calculations.

[0103] S3. Calculate tire size using an interpolation method and, in combination with the motor speed and torque, calculate vehicle speed and vehicle traction. This specifically includes the following steps: Shovel a fixed mass block, measure the axle loads of the front and rear drive axles and the corresponding tire radius, and thereby obtain tire size under multiple sets of axle load data; calculate the axle loads of the front and rear drive axles based on the center of mass positions of the working device components and the vehicle as a whole, according to force and torque balance relationships; and interpolate tire size based on the calculated axle loads of the front and rear drive axles. Finally, calculate vehicle speed and vehicle traction using the calculated tire size in combination with the motor speed and torque.

[0104] S4. Calculate the bucket cylinder force and the boom cylinder force based on the bucket cylinder pressure and boom cylinder pressure, combined with the structural dimensions of the hydraulic cylinder, and determine whether the bucket cylinder pressure exceeds a set threshold. The bucket cylinder force correction method includes:

[0105] Based on the acquired bucket cylinder extension, boom cylinder extension, bucket cylinder pressure, boom cylinder pressure, motor speed and torque, and according to the characteristics of different operation stages, a completed operation cycle is divided into stages such as no-load forward, digging, full-load transportation, boom lifting, unloading, and boom falling.

[0106] The calculated vehicle traction force, bucket cylinder force, and boom cylinder force are divided into different operation phases. The data in different operation phases are processed using corresponding methods, including: fully loaded transportation and boom raising phases. When the bucket cylinder pressure exceeds the set threshold, the bucket cylinder force is corrected based on the boom cylinder force:

[0107]

[0108] Among them, F FDG is the force acting on the rear dump cylinder, m i is the mass of component i; g is the acceleration due to gravity; L mi is the horizontal distance between the center of mass of component i and the hinge position between the boom and the front frame; L1 is the force arm of the boom cylinder force at the hinge position between the boom and the front frame; L2 is the horizontal distance between the center of mass of the load and the hinge position between the boom and the front frame; L3 is the force arm of the dump cylinder force at the hinge position between the boom and the front frame; r is the force transmission ratio of the dump mechanism; F DBG is the force of the boom cylinder.

[0109] S5. Input the calculated center of mass position and rotation angle of each component of the working device, vehicle speed, vehicle traction, bucket cylinder force, and boom cylinder force into a pre-established dynamics algorithm model to calculate the forces acting at each joint and the load acting on the bucket during operation. This step specifically includes the following sub-steps:

[0110] First, the translational acceleration and angular acceleration of the component are calculated based on the component's center of mass position, rotation angle, and vehicle speed. Second, the dynamic equation is constructed based on the Newton-Euler method according to the connection relationship between the components:

[0111] AX=B

[0112] Where A is:

[0113]

[0114] Where n is the number of components, m is the number of hinge points, and submatrix a ij Represents the contribution of the force at the j-th joint to the force balance and moment balance of the i-th component, submatrix a i(m+1) represents the contribution of the operating load to the force balance and moment balance of the i-th component;

[0115] X is:

[0116]

[0117] Where, F Mj_x 、F Mj_y represents the force at the hinge point Mj; F x 、Fy 、T z is the operating load acting on the bucket;

[0118] B is:

[0119] B=B inertial +B external

[0120] Among them, B inertial is the inertia force matrix; B extermal It is a matrix composed of known external forces such as the bucket cylinder force and the boom cylinder force.

[0121] Finally, the dynamic equations are solved to obtain the forces acting on each joint during the operation and the operating load acting on the bucket, and the operating load spectrum is obtained using the operating load.

[0122] This embodiment compares the load spectrum calculated by the above method with the test results of the pin sensor. The results are as follows: Figure 4 and Figure 5 As shown, it can be seen that the calculation method in the embodiment of the present invention is more accurate.

[0123] On the other hand, Figure 2 As shown, the present invention also provides a wheel loader reliability analysis system for a wheel loader operating load spectrum analysis method, which includes: a data acquisition module for obtaining the bucket cylinder extension, boom cylinder extension, bucket cylinder pressure, boom cylinder pressure, motor speed, and motor torque; a kinematic calculation module for calculating the center of mass position and rotation angle of each component of the working device and the position of each hinge point; a tire size calculation module for calculating tire size through interpolation; a bucket cylinder force correction module for correcting the bucket cylinder force; and a dynamic calculation module for calculating the forces at each hinge during operation and the operating load acting on the bucket, i.e., the operating load spectrum. In other embodiments, a reliability analysis module may also be provided for analyzing the structural reliability of each loader component using the operating load spectrum.

[0124] In some specific embodiments, a storage medium and a processor are further included; the storage medium is used to store instructions; and the processor is used to operate according to the instructions to execute the above-mentioned calculation method.

[0125] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0126] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0127] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0128] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0129] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for analyzing a wheel loader operating load spectrum, characterized by: It includes the following steps: S1. Obtain the bucket cylinder extension, boom cylinder extension, bucket cylinder pressure, boom cylinder pressure, motor speed, and motor torque; S2. Based on the kinematic model of the loader's working linkage mechanism and the acquired bucket cylinder extensions and boom cylinder extensions, calculate the center of mass position and rotation angle of each component of the wheel loader's working device, as well as the positions of each hinge point; S3. Obtain tire size and calculate vehicle speed and vehicle traction based on motor speed and motor torque; S4. Calculate the bucket cylinder force and the boom cylinder force based on the bucket cylinder pressure and the boom cylinder pressure. When the bucket cylinder pressure exceeds the set threshold, correct the bucket cylinder force: Among them, F FDG is the force of the modified dump cylinder, m i is the mass of component i; g is the acceleration due to gravity; L mi is the horizontal distance between the center of mass of component i and the hinge position between the boom and the front frame; L1 is the force arm of the boom cylinder force at the hinge position between the boom and the front frame; L2 is the horizontal distance between the center of mass of the load and the hinge position between the boom and the front frame; L3 is the force arm of the dump cylinder force at the hinge position between the boom and the front frame; r is the force transmission ratio of the dump mechanism; F DBG is the force of the boom cylinder; S5. Construct a dynamic algorithm model and input the calculated center of mass position and rotation angle of each component of the working device, vehicle speed, vehicle traction, bucket cylinder force, and boom cylinder force into the dynamic algorithm model. Calculate the forces acting at each articulation during the operation and the operating load acting on the bucket, and obtain the operating load spectrum based on the operating load.

2. The method for analyzing the operating load spectrum of a wheel loader according to claim 1, wherein: The method for obtaining the tire size in step S3 specifically includes the following sub-steps: S31. According to a fixed-mass weight block, the bridge loads of the front drive axle and the rear drive axle and the corresponding tire radius are measured to obtain the tire size under multiple sets of bridge load data; S32. According to the center of mass position of each component of the working device, the whole vehicle is taken as the research object, and the bridge loads of the front drive axle and the rear drive axle are calculated according to the force balance and torque balance relationship; S33. Based on the calculated bridge loads of the front drive axle and the rear drive axle, the tire size is obtained by interpolation method.

3. The method for analyzing the operating load spectrum of a wheel loader according to claim 2, wherein: Step S3 specifically includes the following sub-steps: In step S32, the equations for solving the bridge loads of the front drive axle and the rear drive axle are as follows: Among them, m i is the mass of component i; F f 、F r are the bridge loads of the front drive axle and the rear drive axle respectively; L i_r L is the horizontal distance from the center of mass of component i to the rear drive axle; f_r It is the horizontal distance from the front drive axle to the rear drive axle.

4. The method for analyzing the operating load spectrum of a wheel loader according to claim 3, wherein: Step S3 specifically includes the following sub-steps: The method for obtaining the tire size by interpolation in step S33 is as follows: Among them, R f 、R r These are the sizes of the front drive axle tires and the rear drive axle tires respectively; Qiaohe Front drive axle tire size below; Qiaohe The rear drive axle tire size is as follows.

5. The method for analyzing the operating load spectrum of a wheel loader according to claim 1, wherein: Step S5 specifically includes the following sub-steps: S51, calculating the translational acceleration and rotational angular acceleration of each component based on the component's center of mass position, rotation angle, and vehicle speed; S52. Constructing a dynamic algorithm model based on the Newton-Euler method according to the connection relationship between the components; S53. Solve the dynamic algorithm model to obtain the forces acting on each hinge during the operation and the operating load acting on the bucket.

6. The method for analyzing the operating load spectrum of a wheel loader according to claim 3, wherein: The dynamic algorithm model constructed in step S52 is specifically: AX=B Where A is: Where n is the number of components, m is the number of hinge points, and submatrix a ij Represents the contribution of the force at the j-th joint to the force balance and moment balance of the i-th component, submatrix a i(m+1) represents the contribution of the operating load to the force balance and moment balance of the i-th component; X is: Where, F Mj_x 、F Mj_y Represents the hinge point M j The force at x 、F y 、T z is the operating load acting on the bucket; B is: B=B inertial +B external Among them, B inertial is the inertia force matrix; B extermal It is a matrix composed of known external forces such as the bucket cylinder force and the boom cylinder force.

7. The method for analyzing the operating load spectrum of a wheel loader according to claim 1, wherein: When the extension of the dump cylinder and the boom cylinder cannot be obtained, the boom angle sensor and the rocker arm angle sensor are used to collect the rotation angle of the boom relative to the front frame and the rotation angle of the rocker arm relative to the boom. Based on the motion model of the loader's working linkage mechanism, the center of mass position and rotation angle of each component of the wheel loader's working device and the position of each hinge point are calculated.

8. The method for analyzing the operating load spectrum of a wheel loader according to claim 1, wherein: In step S1, the elongation of the bucket cylinder, the elongation of the boom cylinder, the pressure of the bucket cylinder, and the pressure of the boom cylinder are measured by sensors, as well as the motor speed and motor torque.

9. A wheel loader reliability analysis system for use with the wheel loader load spectrum analysis method according to any one of claims 1 to 8, characterized in that: It includes: A data acquisition module is used to obtain the extension of the bucket cylinder, the extension of the boom cylinder, the pressure of the bucket cylinder, the pressure of the boom cylinder, the motor speed and the motor torque; Kinematics calculation module, used to calculate the center of mass position and rotation angle of each component of the working device and the position of each hinge point; The tire size calculation module is used to calculate tire size through interpolation method; the bucket cylinder force correction module is used to correct the bucket cylinder force; the dynamics calculation module is used to calculate the forces at each articulation point during the operation and the operating load acting on the bucket, that is, the operating load spectrum.

10. The wheel loader reliability analysis system according to claim 9, characterized in that: It also includes a storage module for storing the operation load spectra of different loaders to obtain an operation load spectrum database for subsequent analysis.

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