A method and device for identifying parameters of low-speed and heavy-load friction torque of a multi-mode hydraulic motor

Abstract

The present invention discloses a method and device for identifying parameters of low-speed and heavy-load friction torque of a multi-modal hydraulic motor. The method analyzes the torque balance of the hydraulic motor, and based on the operating conditions of the hydraulic motor, establishes a low-speed and heavy-load friction torque model suitable for the hydraulic motor; designs a set of constant-pressure variable-speed sweep frequency trajectories and a set of constant-speed variable-pressure trajectories to carry out steady-state friction parameter identification; controls the variable-speed operation of the hydraulic motor, designs constant-pressure variable-speed excitation trajectories that meet continuous excitation conditions, and carries out dynamic friction parameter identification. The present invention establishes a low-speed and heavy-load friction torque model suitable for the hydraulic motor, and proposes a model parameter hybrid identification framework based on the model. The framework consists of a steady-state friction parameter identification link and a dynamic friction parameter identification link. By designing excitation trajectories under the links respectively, the friction torque parameter identification can be completed, which is more systematic and engineering-oriented than traditional methods.

Description

Technical Field

[0001] The invention belongs to the field of nonlinear dynamics and system identification, and particularly relates to a method and device for identifying parameters of low-speed and heavy-load friction torque of a multi-mode hydraulic motor. Background Art

[0002] Friction is a common phenomenon in motion machinery. It is a complex nonlinear characteristic inherent in motion systems. Quantitative and accurate description of friction characteristics is of great significance for improving the performance of motion control systems. Especially in the development of high-end equipment, the influence of friction is particularly important due to important indicators such as maneuverability, load-bearing capacity and endurance. Hydraulic motors are widely used in high-performance hydraulic servo devices. In order to improve the dynamic characteristics and control accuracy of hydraulic servo systems, it is necessary to accurately model and identify the friction torque. However, the traditional LuGre friction model is a pure speed function and is not suitable for low-speed and heavy-load conditions of hydraulic motors. At the same time, since it is in the form of a nonlinear equation group containing many parameters, it is extremely difficult to accurately identify the parameters. The traditional friction parameter identification method requires adjusting the controller parameters, and the control system generates multiple sets of limit cycle oscillation curves in the pre-slip stage. The experimental conditions are harsh and the experimental process is cumbersome, which is difficult to promote in engineering practice.

[0003] Therefore, in order to improve the performance of the hydraulic servo system, guide the design of the system's high-precision controller and carry out friction compensation, it is necessary to propose a low-speed and heavy-load friction torque parameter identification method for hydraulic motors for engineering applications.

[0004] In summary, the present invention proposes a method for identifying parameters of low-speed and heavy-load friction torque of a multi-modal hydraulic motor, which can better model and calculate the friction torque of the hydraulic motor and is easier to implement in industrial application scenarios. Summary of the invention

[0005] In view of the challenges that the current hydraulic motor friction model parameter high-precision identification is difficult to carry out and difficult to achieve in engineering, the present invention proposes a multi-modal hydraulic motor low-speed heavy-load friction torque parameter identification method and device, establishes a low-speed heavy-load friction torque model suitable for hydraulic motors and a model parameter hybrid identification framework. The friction parameters are divided into steady-state friction parameters and dynamic friction parameters, and the excitation trajectories are designed respectively, so that the friction torque parameter identification can be completed, which has good systematicity and engineering properties.

[0006] The object of the present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a method for identifying parameters of low-speed and heavy-load friction torque of a multi-mode hydraulic motor, the method comprising the following steps:

[0007] Step 1: Analyze the torque balance of the hydraulic motor, and establish a low-speed and heavy-load friction torque model suitable for the hydraulic motor based on the operating conditions of the hydraulic motor; define the parameters directly related to the steady-state friction torque in the low-speed and heavy-load friction torque model as steady-state friction parameters, and the remaining parameters to be identified are dynamic friction parameters;

[0008] Step 2: Carry out steady-state friction parameter identification, design a set of constant pressure variable speed sweep trajectories and a set of constant speed variable pressure trajectories, control the hydraulic motor to carry out friction torque test under the corresponding trajectories, and use the nonlinear least squares method to identify the steady-state friction parameters;

[0009] Step 3: Carry out dynamic friction parameter identification, control the variable speed operation of the hydraulic motor, design a constant pressure variable speed excitation trajectory that meets the continuous excitation conditions, control the hydraulic motor to work under the pre-slip condition, and combine the steady-state parameters obtained in step 2 to identify the dynamic friction parameters using the nonlinear least squares method.

[0010] Furthermore, in step 1, the torque balance of the hydraulic motor is analyzed, and the friction torque model is established based on the LuGre friction model considering the low-speed and heavy-load working characteristics of the hydraulic motor;

[0011] To pre-establish the low-speed heavy-load friction torque model of the hydraulic motor, it is first necessary to analyze its force conditions and establish the torque balance equation:

[0012]

[0013] in, is the displacement of the hydraulic motor, is the oil inlet pressure, is the oil outlet pressure, is the moment of inertia of the radial piston pump / motor, is the angular acceleration, is the load torque, is the friction torque;

[0014] Based on the LuGre friction model, combined with the working characteristics and operation principle of the hydraulic motor, the low-speed heavy-load friction torque model is established as follows:

[0015]

[0016] in, is the friction torque; w is the relative angular velocity of the contact surface; z is the state value representing the average bristle deformation, indicating the deformation amount at the microscopic level of the interface; is the bristle deformation change rate; g(w) is the Stribeck characteristic; is the bristle stiffness; is the bristle damping coefficient; is the viscous friction coefficient; is the Coulomb friction torque; is the maximum static friction torque; is the Stribeck angular velocity, represents the Coulomb friction coefficient; represents the static friction coefficient; represents the no-load Coulomb friction torque; Indicates the no-load static friction torque.

[0017] Furthermore, when the system is in a uniform speed state, the average bristle deformation z remains unchanged, so , we can get:

[0018]

[0019] Therefore, the steady-state friction torque at uniform speed is It is expressed as:

[0020]

[0021] It can be seen that the steady-state friction torque With parameters , , , , , The definition of low speed heavy load friction torque model is related to The directly related parameters are steady-state friction parameters, and the remaining parameters to be identified are dynamic friction parameters.

[0022] Furthermore, the specific process of step 2 is:

[0023] (1) Identification parameters , :Fixed pressure p, so that the angular velocity changes from the minimum angular velocity Gradually change the frequency to the maximum angular velocity. After the kth frequency change, the angular velocity signal w(k) is:

[0024]

[0025] Among them, dw is the change of the sweep frequency angular velocity. According to the angular velocity sweep frequency trajectory test in the above formula, the average friction torque at a certain angular velocity is calculated as the friction torque measured at the current angular velocity. , applying the nonlinear least squares method makes:

[0026]

[0027] Based on the steady-state friction torque formula at uniform speed, the parameters are determined and The optimal value of , where n represents the number of measurement points, represents the angular velocity of the i-th measurement point;

[0028] (2) Identification parameters , :When w=0, At different pressures Repeat the steps in (1) to determine the coefficients multiple times and draw multiple fitting curves , determine the curve Intersection with vertical axis , you can get the parameters , ;

[0029] (3) Identification parameters , :when , , at a certain speed is a constant; therefore, the angular velocity tested under different pressures at the same angular velocity Carry out different pressure tests under different conditions and design constant speed variable pressure trajectory:

[0030]

[0031] in, For current pressure; is the minimum pressure; For pressure changes;

[0032] Draw a curve ,different The lower curve results are approximately linear and nearly parallel, so after fitting The slope of the straight line is , intersection with the vertical axis , calculated from this .

[0033] Furthermore, the angular velocity frequency conversion process is as follows: In order to improve the test efficiency and consistency, it is necessary to design a minimum angular velocity under a certain pressure p. To maximum angular velocity The angular velocity sweep trajectory makes the hydraulic motor reciprocate at an increasing constant speed, that is, it rotates forward from the starting position 0 to the maximum stroke A and then immediately reverses, and the angular velocity increases after reaching the starting position, and the cycle continues.

[0034] Furthermore, in step 3, the dynamic friction parameters are pre-identified, and the hydraulic motor needs to be controlled to change speed. The low-speed heavy-load friction torque model is expressed as dynamic friction torque, angular acceleration , hydraulic motor torque loss for:

[0035]

[0036] in, It is measured experimentally, but the moment of inertia With dynamic friction Coupling needs to be identified together; therefore, the model dynamic parameters to be identified are: , , .

[0037] Furthermore, the specific process of step three is:

[0038] (1) The bristle deformation z is a microscopic quantity and cannot be directly measured. When the object is in the extremely low-speed pre-slip stage, it is approximately considered , x represents the macroscopic displacement of the hydraulic motor, Indicates the angle, represents the macro speed, represents the angular velocity, then , we can get:

[0039]

[0040] in, and All are directly measured quantities. Obtained by differentiation;

[0041] (2) The dynamic friction parameters are analyzed to be independent of the pressure p. Therefore, under a certain pressure p, the variable speed excitation trajectory is designed:

[0042]

[0043] Where m represents the order of the trajectory signal, represents the trajectory amplitude; represents the trajectory frequency; represents the trajectory phase; the number of pre-identified parameters is 3, and m=2 can be determined based on the continuous excitation PE condition and the minimum condition number; at the same time, in order to meet the low-speed pre-slip condition, the trajectory constraint conditions are designed: , ;

[0044] (3) Control the hydraulic motor to track the variable speed excitation trajectory, test and calculate the torque loss under variable speed excitation , applying the nonlinear least squares method makes:

[0045]

[0046] Thus, the dynamic parameters of the low-speed and heavy-load friction model of the hydraulic motor are obtained. , , .

[0047] In a second aspect, the present invention provides a device for identifying the parameters of a multi-modal hydraulic motor with low speed and heavy load friction torque, comprising a memory and one or more processors, wherein the memory stores executable code, and when the processor executes the executable code, it implements the method for identifying the parameters of a multi-modal hydraulic motor with low speed and heavy load friction torque.

[0048] In a third aspect, the present invention provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the method for identifying parameters of a multi-modal hydraulic motor low-speed and heavy-load friction torque.

[0049] In a fourth aspect, the present invention provides a computer program product, including a computer program, which, when executed by a processor, implements the method for identifying parameters of a multi-mode hydraulic motor low-speed and heavy-load friction torque.

[0050] Beneficial effects of the present invention:

[0051] The invention provides a method for identifying the parameters of a multi-modal hydraulic motor with low speed and heavy load friction torque, which can effectively solve the problem of difficulty in identifying the friction parameters of hydraulic motors and low identification accuracy in industrial application scenarios. The friction torque parameter identification method of the invention is systematic, simple and engineering, especially in the aspects of hydraulic motor friction torque modeling and high-precision parameter identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 A flow chart of a method for identifying parameters of low-speed and heavy-load friction torque of a multi-modal hydraulic motor provided by the present invention.

[0053] Figure 2 This is a measured diagram of the friction torque of a certain type of hydraulic motor under constant speed and variable pressure conditions.

[0054] Figure 3 This is a measured diagram of the friction torque of a certain type of hydraulic motor under constant pressure and variable speed conditions.

[0055] Figure 4 This is a flow chart of the parameter identification method.

[0056] Figure 5 This is a structural diagram of a multi-modal hydraulic motor low-speed and heavy-load friction torque parameter identification device provided by the present invention. DETAILED DESCRIPTION

[0057] The present invention is described in detail below with reference to the accompanying drawings and specific examples:

[0058] like Figure 1As shown, the present invention performs friction torque testing on a certain type of hydraulic motor to implement a method for identifying parameters of low-speed and heavy-load friction torque of a multi-modal hydraulic motor.

[0059] like Figure 2 As shown, multiple tests were carried out with variable pressure at constant speed, and the friction torque at a certain angular velocity was calculated. It was found that: at the same angular velocity, the friction torque It has a good linear relationship with pressure p. Figure 3 As shown, the friction torque under constant pressure and speed change is calculated and found that: under the same pressure, the friction torque The relationship between the angular velocity w also shows a Stribeck trend, which is consistent with the traditional LuGre model.

[0060] To pre-establish the low-speed heavy-load friction torque model of the hydraulic motor, it is first necessary to analyze its force conditions and establish the torque balance equation:

[0061]

[0062] in, is the displacement of the hydraulic motor, is the oil inlet pressure, is the oil outlet pressure, is the moment of inertia of the radial piston pump / motor, is the angular acceleration, is the load torque, is the friction torque;

[0063] Under uniform speed conditions, , the steady-state friction torque can be expressed as:

[0064]

[0065] In variable speed conditions, , the dynamic friction torque can be expressed as:

[0066]

[0067] The low-speed heavy-load friction torque model is proposed to address the application limitations of the traditional LuGre friction model in the hydraulic field. The traditional LuGre friction model is a pure speed function and is expressed as follows for the rotating system:

[0068]

[0069] in, is the friction torque; w is the relative angular velocity of the contact surface; z is the state value representing the average bristle deformation, indicating the deformation amount at the microscopic level of the interface; is the bristle deformation change rate; g(w) is the Stribeck characteristic; is the bristle stiffness; is the bristle damping coefficient; is the viscous friction coefficient; is the Coulomb friction torque; is the maximum static friction torque; is the Stribeck angular velocity.

[0070] A large number of steady-speed tests were carried out on hydraulic motors to make them run at a constant speed under different pressures and speeds, and to analyze the friction torque at a certain speed. It was found that at the same speed, the friction torque It has a good linear relationship with the pressure p; under the same pressure, the friction torque The relationship between the velocity and the velocity v also shows a Stribeck trend, which is consistent with the traditional LuGre friction model.

[0071] Consider the effect of pressure p in the LuGre friction model. Coulomb friction and maximum static friction Both are related to the interface contact state and are directly affected by pressure and lubrication state. and maximum static friction torque Corrected as a function of pressure p, and It is expressed as follows:

[0072]

[0073] in, represents the Coulomb friction coefficient; represents the static friction coefficient; represents the no-load Coulomb friction torque; Indicates the no-load static friction torque.

[0074] Based on the traditional LuGre friction model, combined with the working characteristics and operation principle of the hydraulic motor, the stress condition of the hydraulic motor is analyzed, and combined with Figure 2 , Figure 3 Based on the measured results, the low-speed and heavy-load friction torque model is established as follows:

[0075]

[0076] Among them, when the system is in a uniform speed state, the average bristle deformation z remains unchanged, so , we can get:

[0077]

[0078] like Figure 4As shown, the model parameter identification method provided by the present invention specifically consists of a static friction parameter identification link and a dynamic friction parameter identification link:

[0079] The specific process of steady-state friction parameter identification is as follows:

[0080] (1) When a certain type of hydraulic motor is controlled to run at a constant speed, its low-speed heavy-load friction torque is expressed as static friction. ;

[0081]

[0082] At this point, the model degenerates into the Stribeck model, indicating good generalization of the model. The directly related parameters are steady-state friction parameters, and the remaining parameters to be identified are dynamic friction parameters. The static model parameters that need to be identified are: , , , , , .

[0083] (2) Identification parameters , In order to improve the test efficiency and consistency, it is necessary to design a range of angular velocities from the minimum angular velocity to the maximum angular velocity ( ~ ) makes a certain type of hydraulic motor reciprocate at an increasing constant speed, that is, it rotates from the starting position 0 to the maximum stroke A and then immediately reverses, and the angular velocity increases after reaching the starting position, and so on. After the kth frequency conversion, the angular velocity change value is as follows:

[0084]

[0085] Where, dw is the change of sweep angular velocity, is the angular velocity change value. The angular velocity signal w(k) at this time is:

[0086]

[0087] According to the angular velocity sweep trajectory test of the above formula, the average friction torque at a certain angular velocity is calculated as the friction torque measured at the current angular velocity. , applying the nonlinear least squares method makes:

[0088]

[0089] Based on the steady-state friction torque formula at uniform speed, the parameters are determined and The optimal value of , where n represents the number of measurement points, Represents the angular velocity of the i-th measurement point. The specific measured results and nonlinear fitting results for a certain model of hydraulic motor are as follows: Figure 3 shown.

[0090] (3) Identification parameters , When w=0, At different pressures Repeat the steps in (2) to determine the coefficients multiple times and draw multiple fitting curves , determine the curve Intersection with vertical axis , you can get the parameters , .

[0091] (4) Identification parameters , .when , , means More than 3 times , at a certain speed is a constant. Therefore, when Different pressure tests are carried out at the same angular velocity. Design a constant speed and variable pressure trajectory for the angular velocity tested at different pressures at the same angular velocity:

[0092]

[0093] in, For current pressure; is the minimum pressure; is the pressure change. Draw a curve ,like Figure 2 As shown, different The lower curve results are approximately linear and nearly parallel, so after fitting The slope of the straight line is , intersection with the vertical axis , calculated from this The specific measured results and nonlinear fitting results for a certain type of hydraulic motor are as follows: Figure 2 shown.

[0094] The specific process of dynamic friction parameter identification is as follows:

[0095] (1) Pre-identify the dynamic parameters of the model, so that a certain type of hydraulic motor is running at variable speed, and the heavy-load lubrication LuGre model is characterized by dynamic friction , angular acceleration , its torque loss for:

[0096]

[0097] in, It is measured experimentally, but the moment of inertia With dynamic friction Coupling needs to be identified together; therefore, the model dynamic parameters to be identified are: , , .

[0098] (2) The bristle deformation z is a microscopic quantity and cannot be directly measured. When the object is in the extremely low-speed pre-slip stage, it can be considered , x represents the macroscopic displacement of the hydraulic motor, Indicates the angle, represents the macro speed, represents the angular velocity, then , we can get:

[0099]

[0100] in, and All are directly measured quantities. It can be obtained through differentiation, so the variable speed excitation trajectory can be designed to complete the dynamic parameter identification.

[0101] (3) Since the dynamic parameters are independent of the pressure p, the variable speed excitation trajectory can be designed under a certain pressure p:

[0102]

[0103] Where m represents the order of the trajectory signal, represents the trajectory amplitude; represents the trajectory frequency; represents the trajectory phase; the number of pre-identified parameters is 3, and m=2 can be determined based on the continuous excitation PE condition and the minimum condition number; at the same time, in order to meet the low-speed pre-slip condition, the trajectory constraint conditions are designed: , .

[0104] (4) Control the hydraulic motor to track the speed change excitation trajectory, test and calculate the torque loss under speed change excitation , applying the nonlinear least squares method makes:

[0105]

[0106] Thus, the dynamic parameters of the hydraulic motor low speed heavy load friction torque model are obtained , , .

[0107] Corresponding to the aforementioned embodiment of a method for identifying parameters of a multi-modal hydraulic motor at low speed and heavy load friction torque, the present invention further provides an embodiment of a device for identifying parameters of a multi-modal hydraulic motor at low speed and heavy load friction torque.

[0108] See also Figure 5 A multi-modal hydraulic motor low-speed and heavy-load friction torque parameter identification device provided in an embodiment of the present invention includes a memory and one or more processors, wherein the memory stores executable code, and when the processor executes the executable code, it is used to implement a multi-modal hydraulic motor low-speed and heavy-load friction torque parameter identification method in the above embodiment.

[0109] An embodiment of a multi-modal hydraulic motor low-speed heavy-load friction torque parameter identification device provided by the present invention can be applied to any device with data processing capabilities, and the device with data processing capabilities can be a device or apparatus such as a computer. The device embodiment can be implemented through software, or through hardware or a combination of software and hardware. Taking software implementation as an example, as a device in a logical sense, it is formed by the processor of any device with data processing capabilities in which it is located reading the corresponding computer program instructions in the non-volatile memory into the internal memory for execution. From a hardware perspective, if Figure 5 As shown in FIG. 1 , a hardware structure diagram of a multi-mode hydraulic motor low-speed heavy-load friction torque parameter identification device provided by the present invention is provided in any device with data processing capability, except Figure 5 In addition to the processor, memory, network interface, and non-volatile memory shown, any device with data processing capabilities in which the apparatus in the embodiments is located may also include other hardware, generally based on the actual functions of the device with data processing capabilities, which will not be described in detail.

[0110] The implementation process of the functions and effects of each unit in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, and will not be repeated here.

[0111] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of the present invention. Ordinary technicians in this field can understand and implement it without paying creative work.

[0112] An embodiment of the present invention further provides a computer-readable storage medium having a program stored thereon. When the program is executed by a processor, a method for identifying parameters of low-speed and heavy-load friction torque of a multi-mode hydraulic motor in the above embodiment is implemented.

[0113] The computer-readable storage medium may be an internal storage unit of any device with data processing capability described in any of the aforementioned embodiments, such as a hard disk or a memory. The computer-readable storage medium may also be an external storage device of any device with data processing capability, such as a plug-in hard disk, a smart media card (SMC), an SD card, a flash card, etc. equipped on the device. Furthermore, the computer-readable storage medium may also include both an internal storage unit and an external storage device of any device with data processing capability. The computer-readable storage medium is used to store the computer program and other programs and data required by any device with data processing capability, and may also be used to temporarily store data that has been output or is to be output.

[0114] The present invention also provides a computer program product, including a computer program. When the computer program is executed by a processor, the method for identifying parameters of low-speed and heavy-load friction torque of a multi-mode hydraulic motor is implemented.

[0115] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for identifying parameters of low-speed and heavy-load friction torque of a multi-mode hydraulic motor, characterized in that: The method comprises the following steps: Step 1: Analyze the torque balance of the hydraulic motor. Based on the operating conditions of the hydraulic motor and the low-speed and heavy-load working characteristics of the hydraulic motor, a low-speed and heavy-load friction torque model suitable for the hydraulic motor is established based on the LuGre friction model. The parameters directly related to the steady-state friction torque in the low-speed and heavy-load friction torque model are defined as steady-state friction parameters, and the remaining parameters to be identified are dynamic friction parameters; specifically: To pre-establish the low-speed heavy-load friction torque model of the hydraulic motor, it is first necessary to analyze its force conditions and establish the torque balance equation: ； in, is the displacement of the hydraulic motor, is the oil inlet pressure, is the oil outlet pressure, is the moment of inertia of the radial piston pump / motor, is the angular acceleration, is the load torque, is the friction torque; Based on the LuGre friction model, combined with the working characteristics and operation principle of the hydraulic motor, the low-speed heavy-load friction torque model is established as follows: ； in, is the friction torque; w is the relative angular velocity of the contact surface; z is the state value representing the average bristle deformation, indicating the deformation amount at the microscopic level of the interface; is the bristle deformation change rate; g(w) is the Stribeck characteristic; is the bristle stiffness; is the bristle damping coefficient; is the viscous friction coefficient; is the Coulomb friction torque; is the maximum static friction torque; is the Stribeck angular velocity, represents the Coulomb friction coefficient; represents the static friction coefficient; represents the no-load Coulomb friction torque; Indicates no-load static friction torque; Step 2: Carry out steady-state friction parameter identification, design a set of constant pressure variable speed sweep trajectories and a set of constant speed variable pressure trajectories, control the hydraulic motor to carry out friction torque test under the corresponding trajectories, and use the nonlinear least squares method to identify the steady-state friction parameters; Step 3: Carry out dynamic friction parameter identification, control the variable speed operation of the hydraulic motor, design a constant pressure variable speed excitation trajectory that meets the continuous excitation conditions, control the hydraulic motor to work under the pre-slip condition, and combine the steady-state parameters obtained in step 2 to identify the dynamic friction parameters using the nonlinear least squares method.

2. A method for identifying parameters of low-speed and heavy-load friction torque of a multi-mode hydraulic motor according to claim 1, characterized in that: When the system is in a uniform speed state, the average bristle deformation z remains unchanged, so , we can get: ； Therefore, the steady-state friction torque at uniform speed is It is expressed as: ； It can be seen that the steady-state friction torque With parameters , , , , , The definition of low speed heavy load friction torque model is related to The directly related parameters are steady-state friction parameters, and the remaining parameters to be identified are dynamic friction parameters.

3. A method for identifying parameters of low-speed and heavy-load friction torque of a multi-mode hydraulic motor according to claim 2, characterized in that: The specific process of step 2 is: (1) Identification parameters , :Fixed pressure p, so that the angular velocity changes from the minimum angular velocity Gradually change the frequency to the maximum angular velocity. After the kth frequency change, the angular velocity signal w(k) is: ； Among them, dw is the change of the sweep frequency angular velocity. According to the angular velocity sweep frequency trajectory test in the above formula, the average friction torque at a certain angular velocity is calculated as the friction torque measured at the current angular velocity. , applying the nonlinear least squares method makes: ； Based on the steady-state friction torque formula at uniform speed, the parameters are determined and The optimal value of , where n represents the number of measurement points, represents the angular velocity of the i-th measurement point; (2) Identification parameters , :When w=0, At different pressures Repeat the steps in (1) to determine the coefficients multiple times and draw multiple fitting curves , determine the curve Intersection with vertical axis , you can get the parameters , ; (3) Identification parameters , :when , , at a certain speed is a constant; therefore, the angular velocity tested under different pressures at the same angular velocity Carry out different pressure tests under different conditions and design constant speed variable pressure trajectory: ； in, For current pressure; is the minimum pressure; For pressure changes; Draw a curve ,different The lower curve results are approximately linear and nearly parallel, so after fitting The slope of the straight line is , intersection with the vertical axis , calculated from this .

4. A method for identifying parameters of low-speed and heavy-load friction torque of a multi-mode hydraulic motor according to claim 3, characterized in that: The specific process of angular velocity frequency conversion is as follows: In order to improve the test efficiency and consistency, it is necessary to design the minimum angular velocity under a certain pressure p. To maximum angular velocity The angular velocity sweep trajectory makes the hydraulic motor reciprocate at an increasing constant speed, that is, it rotates forward from the starting position 0 to the maximum stroke A and then immediately reverses, and the angular velocity increases after reaching the starting position, and the cycle continues.

5. The method for identifying parameters of low-speed and heavy-load friction torque of a multi-mode hydraulic motor according to claim 2, characterized in that: In step 3, the dynamic friction parameters are pre-identified. The hydraulic motor needs to be controlled to change speed. The low-speed heavy-load friction torque model is expressed as dynamic friction torque, angular acceleration , hydraulic motor torque loss for: ； in, It is measured experimentally, but the moment of inertia With dynamic friction Coupling needs to be identified together; therefore, the model dynamic parameters to be identified are: , , .

6. A method for identifying parameters of low-speed and heavy-load friction torque of a multi-mode hydraulic motor according to claim 5, characterized in that: The specific process of step three is: (1) The bristle deformation z is a microscopic quantity and cannot be directly measured. When the object is in the extremely low-speed pre-slip stage, it is approximately considered , x represents the macroscopic displacement of the hydraulic motor, Indicates the angle, represents the macro speed, represents the angular velocity, then , we can get: ； in, and All are directly measured quantities. Obtained by differentiation; (2) The dynamic friction parameters are analyzed to be independent of the pressure p. Therefore, under a certain pressure p, the variable speed excitation trajectory is designed: ； Where m represents the order of the trajectory signal, represents the trajectory amplitude; represents the trajectory frequency; represents the trajectory phase; the number of pre-identified parameters is 3, and m=2 can be determined based on the continuous excitation PE condition and the minimum condition number; at the same time, in order to meet the low-speed pre-slip condition, the trajectory constraint conditions are designed: , ; (3) Control the hydraulic motor to track the variable speed excitation trajectory, test and calculate the torque loss under variable speed excitation , applying the nonlinear least squares method makes: ； Thus, the dynamic parameters of the low-speed and heavy-load friction model of the hydraulic motor are obtained. , , .

7. A multi-mode hydraulic motor low-speed heavy-load friction torque parameter identification device, comprising a memory and one or more processors, wherein the memory stores executable code, characterized in that: When the processor executes the executable code, a method for identifying parameters of low-speed and heavy-load friction torque of a multi-modal hydraulic motor as described in any one of claims 1-6 is implemented.

8. A computer-readable storage medium having a program stored thereon, characterized in that: When the program is executed by a processor, a method for identifying parameters of low-speed and heavy-load friction torque of a multi-modal hydraulic motor as described in any one of claims 1 to 6 is implemented.

9. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, a method for identifying parameters of low-speed and heavy-load friction torque of a multi-modal hydraulic motor as described in any one of claims 1 to 6 is implemented.

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