Electric cylinder friction force parameter and state simultaneous estimation method and device and medium thereof

Abstract

The invention discloses an electric cylinder friction force parameter and state simultaneous estimation method and device and a medium. Aiming at the stick-slip phenomenon and the oscillation phenomenon caused by friction force in low-speed movement, the friction force model of the servo electric cylinder is constructed by combining a traditional static friction force model and a dynamic LuGre friction force model. And on the basis, according to a moment balance equation, a dynamic model of the servo electric cylinder is established. A motion state predictor of the servo electric cylinder is designed by means of a kinetic model and a friction force model of the servo electric cylinder. And updating a friction force state estimation error by using the motion state prediction error, designing a friction force state observer, and estimating the friction force state. In combination with the estimation of the friction force state, the self-adaptive law of the friction force model parameters is constructed, and the friction force model parameters are estimated online, so that the precise estimation of the friction force borne by the servo electric cylinder is realized, and the precise compensation effect of the servo electric cylinder system on the friction force is realized.

Description

Technical Field

[0001] The invention relates to the technical field of control engineering, and in particular to a method for simultaneously estimating friction parameters and states of an electric cylinder, and a device and medium thereof. Background Art

[0002] The servo electric cylinder is a common servo system. It is widely used in six-degree-of-freedom motion platforms. The parallel platform is suitable for motion simulation and motion compensation in multiple industrial fields due to its high rigidity, strong load-bearing capacity, and high motion accuracy. The servo electric cylinder uses a ball screw to convert the rotational motion of the servo motor into the linear motion of the inertial load. However, the transmission method of the ball screw rotation will cause nonlinear friction between the ball screw and the nut, which affects the motion performance of the servo electric cylinder. In order to make the motion control of the servo electric cylinder have higher accuracy, it is necessary to design a compensation method for nonlinear friction.

[0003] Compensation for nonlinear friction is usually performed through a friction model. Since the traditional static friction model has a poor fitting effect on nonlinear friction, modelers in related technologies mainly use dynamic friction models to model nonlinear friction in servo electric cylinder models. In the process of modeling the dynamic friction model, some unknown parameters and states need to be identified by modelers. However, most solutions assume that some parameters in the dynamic friction model are known, but the state is unknown, and only the friction state is estimated. This leads to deficiencies in the modeling of the friction model and the identification of friction parameters, and the model effect is extremely dependent on the assumed model parameters, resulting in certain limitations in the estimation and compensation of friction, and greatly affecting the control accuracy and motion performance of the servo electric cylinder system. Summary of the invention

[0004] In view of this, an embodiment of the present invention provides a method for simultaneously estimating friction parameters and states of an electric cylinder, and a device and medium thereof.

[0005] A first aspect of the present invention provides a method for simultaneously estimating friction parameters and states of an electric cylinder, comprising a linear system parameter estimation part and a friction state estimation and parameter estimation part;

[0006] The linear system parameter estimation part includes the following steps:

[0007] Establishing a dynamic model of the servo electric cylinder system according to its dynamic characteristics, and designing a motion state predictor based on the electric cylinder system model;

[0008] The motion state of the servo electric cylinder system is measured by a photoelectric encoder to obtain a motion state measurement value, and a motion state prediction value is obtained by means of the motion state predictor;

[0009] Subtracting the motion state measurement value from the motion state prediction value to obtain a motion state prediction error;

[0010] Designing a linear system parameter adaptive law in combination with the motion state prediction value and the motion state prediction error to obtain a linear system parameter estimation value;

[0011] The friction state estimation and parameter estimation part includes the following steps:

[0012] Decomposing the electric cylinder system model to obtain a friction model, and designing a friction state observer based on the friction model;

[0013] Inputting the motion state prediction value into the friction state observer to obtain a friction state estimation value;

[0014] Designing a friction state estimation error update law in combination with the motion state prediction error to obtain a friction state estimation error;

[0015] A friction parameter adaptive law is designed in combination with the friction force state estimation value and the friction force state estimation error to obtain the friction force parameter estimation value.

[0016] Further, the electric cylinder system model includes a friction model and an electric cylinder dynamics model;

[0017] Wherein, the friction force model includes a static friction force model and a dynamic friction force model;

[0018] The static friction model includes the following formula:

[0019] F f1 =F c sgn(w)+F v w;

[0020] Among them, F c represents the steady-state value associated with the friction state z, F v represents the steady-state value associated with the viscous friction coefficient α'2, and w represents the speed of the servo electric cylinder motor;

[0021] The dynamic friction model is obtained by improving the static friction model based on the LuGre friction model; the LuGre friction model includes the following formula:

[0022]

[0023] Among them, σ0 represents the bristle stiffness of the servo electric cylinder, which is abstracted from the LuGre friction model, σ1 represents the damping coefficient of the servo electric cylinder, which is abstracted from the LuGre friction model, α'2 represents the viscous friction coefficient of the servo electric cylinder, which is abstracted from the LuGre friction model, z represents the friction state of the servo electric cylinder, which is abstracted from the LuGre friction model, β0 represents the friction parameter of the servo electric cylinder, σ0α0 represents the Coulomb friction of the servo electric cylinder, σ0(α0+α1) represents the static friction of the servo electric cylinder, which is abstracted from the LuGre friction model, v s Indicates the stribeck speed;

[0024] Introducing a switching function s(|w|) into the LuGre friction model to obtain the dynamic friction model;

[0025] The switching function s(|w|) is expressed in the following form:

[0026]

[0027] Among them, g1 represents the upper threshold, and g2 represents the lower threshold;

[0028] The dynamic friction model is expressed as:

[0029]

[0030] The electric cylinder dynamics model is established according to the torque balance equation of the servo electric cylinder. The torque balance equation is as follows:

[0031]

[0032] Where J represents the moment of inertia of the servo electric cylinder, θ represents the rotation angle of the servo electric cylinder motor, the superscript “·” represents the derivative, the superscript “··” represents the second-order derivative, T e Indicates the electromagnetic torque of the servo electric cylinder motor, F f Indicates the friction torque of the servo electric cylinder motor, T l Indicates the load force of the servo electric cylinder motor;

[0033] T r =K h T l , P represents the lead of the servo electric cylinder;

[0034] Define x1 = θ, which represents the rotation angle of the servo electric cylinder motor. represents the speed of the servo electric cylinder motor; then the torque balance equation of the servo electric cylinder can be expressed as:

[0035]

[0036] Among them, K p represents the input torque ratio, u represents the given current signal input,

[0037] The rotation angle x1 of the servo electric cylinder motor is directly proportional to the lead P of the servo electric cylinder:

[0038] y=Px1;

[0039] because Therefore, the electric cylinder system model is expressed as:

[0040]

[0041] make Then the electric cylinder system model is simplified as:

[0042]

[0043] Furthermore, the motion state predictor is expressed in the following form:

[0044]

[0045] Wherein, λ represents the design parameter of the motion state predictor, λ>0; the superscript “^” represents an estimated value, and the superscript “~” represents an error value;

[0046] Then the motion state prediction error is:

[0047]

[0048] ε represents the sliding mode function, which is expressed in the following form:

[0049]

[0050] Further, the linear system parameters include γ1, γ5 and γ7;

[0051] The linear system parameter adaptation law is expressed in the following form:

[0052]

[0053] Among them, η1>0, η5>0, η7>0, k1>0, k5>0, k7>0 are all adaptive gains.

[0054] Furthermore, the friction state observer is a dual observer structure, which observes the friction state z in the friction model and obtains z0 and z1 as respective friction state estimation values; the friction state observer is expressed by the following formula:

[0055]

[0056] Wherein, r1 and r2 represent the design parameters of the friction state observer, r1>0, r2>0;

[0057] l1 and l2 are robust terms, expressed in the following form:

[0058]

[0059] The superscript “^” indicates an estimated value, and the superscript “~” indicates an error value;

[0060] is the estimated value of the friction parameter β0.

[0061] Furthermore, the friction state estimation error includes:

[0062]

[0063] The friction state estimation error update law is expressed as follows:

[0064]

[0065] Further, the friction force parameters include γ2, γ3, γ2, γ6 and β0;

[0066] The friction force parameter adaptive law is expressed in the following form:

[0067]

[0068] Among them, η2>0, η3>0, η4>0, η6>0, η8>0, k2>0, k3>0, k4>0, k6>0, k8>0 are all adaptive gains.

[0069] Furthermore, the method further comprises the following steps:

[0070] Adaptively optimizing the friction state observer using the friction parameter estimate;

[0071] The motion state predictor is adaptively optimized using the linear system parameter estimation value, the friction state estimation value and the friction parameter estimation value.

[0072] A second aspect of the present invention discloses an electronic device, including a processor and a memory;

[0073] The memory is used to store programs;

[0074] The processor executes the program to implement the method for simultaneously estimating the friction force parameters and state of an electric cylinder.

[0075] A third aspect of the present invention discloses a computer-readable storage medium, wherein the storage medium stores a program, and the program is executed by a processor to implement the method for simultaneously estimating the friction force parameters and state of an electric cylinder.

[0076] The embodiment of the present invention also discloses a computer program product or a computer program, which includes a computer instruction stored in a computer-readable storage medium. A processor of a computer device can read the computer instruction from the computer-readable storage medium, and the processor executes the computer instruction, so that the computer device executes the above method.

[0077] The embodiments of the present invention have the following beneficial effects: The present invention aims at the stick-slip phenomenon and oscillation phenomenon caused by friction in low-speed motion, combines the traditional static friction model with the dynamic LuGre friction model, and constructs a friction model of the servo electric cylinder. On this basis, according to the torque balance equation, a dynamic model of the servo electric cylinder is established. With the help of the dynamic model and friction model of the servo electric cylinder, its motion state predictor is designed. The friction state estimation error is updated using the motion state prediction error, and a friction state observer is designed to estimate the friction state. In combination with the estimation of the friction state, an adaptive law of the friction model parameters is constructed, and the friction model parameters are estimated online. The present invention can effectively estimate the friction state and friction parameters of the servo electric cylinder at the same time, and effectively reduce the estimation error of the servo electric cylinder system; thereby achieving accurate estimation of the friction force exerted on the servo electric cylinder, so as to achieve accurate compensation effect of the servo electric cylinder system on the friction force.

[0078] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0080] Figure 1 It is a schematic diagram of the physical structure of the servo electric cylinder system.

[0081] Figure 2 It is a main implementation flow chart of a method for simultaneously estimating friction parameters and states of an electric cylinder according to the present invention.

[0082] Figure 3 It is a schematic diagram of the structural principle of a method for simultaneously estimating friction force parameters and states of an electric cylinder of the present invention.

[0083] Figure 4 It is a comparison curve diagram of the motion state measurement value and the motion state prediction value of the servo electric cylinder system in the embodiment of the present invention.

[0084] Figure 5 It is a comparison diagram of the friction state z0 estimation curve and the actual curve of the servo electric cylinder system through the friction model in the embodiment of the present invention.

[0085] Figure 6 It is a comparison diagram between an estimated curve and an actual curve of the friction state z1 of the servo electric cylinder system through a friction model in an embodiment of the present invention.

[0086] Figure 7 It is a comparison diagram between the estimated curve and the actual curve of the friction state β0 of the servo electric cylinder system through the friction model in the embodiment of the present invention.

[0087] Figure 8 It is a structural schematic diagram of an electronic device of the present invention.

[0088] Fig. 9 It is a schematic diagram of the structure of a computer-readable storage medium of the present invention.

[0089] Figure markings: 1-servo motor, 2-rear base plate, 3-synchronous wheel, 4-synchronous belt, 5-synchronous wheel, 6-rear fork hinge, 7-pulley cover, 8-rolling bearing, 9-screw nut, 10-ball screw, 11-piston rod, 12-cylinder body, 13-sliding bearing, 14-front end cover, 15-front fork hinge. DETAILED DESCRIPTION

[0090] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0091] The servo electric cylinder system consists of a servo motor, a lead screw nut, a screw, a ball screw, a piston rod, etc. The structural diagram is shown in the figure. Figure 1As shown. The servo electric cylinder system will have complex nonlinear friction during the movement process, which will affect the accuracy and stability of the servo electric cylinder system to a certain extent. Therefore, it is necessary to deal with this nonlinear friction. The commonly used method is to offset the influence of nonlinear friction on the servo electric cylinder by accurately compensating for the nonlinear friction. Due to the characteristics and complexity of the friction model, how to obtain the unknown nonlinear friction state and friction parameters has always been a very challenging task.

[0092] With the research on friction models in recent years, most researchers use the LuGre dynamic friction model to model the nonlinear friction in the servo electric cylinder model. The LuGre dynamic friction model simulates the friction phenomenon as the interaction between the bristles on the contact surface. The bottom bristles are fixed and the upper bristles are elastic. When the tangential force acts on the bristles, the bristles will generate deformation force like a spring. When the deformation is large enough, the bristles will begin to slip. The parameters involved in the LuGre dynamic friction model include bristle stiffness, damping coefficient, viscous friction coefficient, etc. By repeatedly optimizing these parameters, the effect of the LuGre dynamic friction model is close to the friction effect of the actual servo electric cylinder. However, there are unknown friction parameters and friction states in the established LuGre friction model, and the problem of how to identify the unknown parameters and states in the LuGre friction model has not been well solved. At present, most of the existing research methods on the problem of LuGre model identification assume that some parameters in the friction model are known, but the state is unknown, and only estimate the friction state, which causes certain deficiencies in the modeling and identification of the LuGre friction model and will greatly reduce the control accuracy of the servo electric cylinder system.

[0093] In order to overcome the problem of LuGre model identification, the first embodiment of the present invention provides a method for simultaneously estimating the friction force parameters and state of an electric cylinder, wherein the implementation process of the scheme is as follows: Figure 2 As shown, the structural principle is as follows Figure 3 The method of the embodiment of the present invention includes a linear system parameter estimation part and a friction state estimation and parameter estimation part.

[0094] The linear system parameter estimation part includes the following steps:

[0095] According to the dynamic characteristics of the servo electric cylinder system, its dynamic model is established, and the motion state predictor is designed based on the electric cylinder system model;

[0096] The motion state of the servo electric cylinder system is measured by a photoelectric encoder to obtain a motion state measurement value, and a motion state prediction value is obtained by means of a motion state predictor;

[0097] Subtract the motion state measurement value from the motion state prediction value to obtain the motion state prediction error;

[0098] The linear system parameter adaptive law is designed by combining the motion state prediction value and the motion state prediction error to obtain the linear system parameter estimation value.

[0099] The friction state estimation and parameter estimation part includes the following steps:

[0100] The friction model is decomposed from the electric cylinder system model, and the friction state observer is designed based on the friction model;

[0101] The motion state prediction value is input into the friction state observer to obtain the friction state estimation value;

[0102] The friction state estimation error update law is designed in combination with the motion state prediction error to obtain the friction state estimation error.

[0103] The friction parameter adaptive law is designed based on the friction state estimation value and the friction state estimation error to obtain the friction parameter estimation value.

[0104] The embodiment of the present invention not only proposes a new method for simultaneously estimating friction state and parameters for key parameters and unknown friction state in the dynamic friction model. At the same time, the system parameters of the servo electric cylinder are also estimated by an adaptive parameter identification method. In short, this method can estimate the system parameters, motion state, friction state and friction key parameters by constructing an observer and designing an adaptive estimation law only through the input and output states of the servo electric cylinder system. It is a method for simultaneously estimating states and parameters.

[0105] The embodiment of the present invention calculates the motion state prediction error and the friction state estimation error based on the system input and the motor angle, motor speed, friction state and the motor angle, motor speed and friction state obtained by the system observer, and constructs an observer based on the motion state prediction error and the friction state estimation error to perform adaptive parameter identification processing on the system parameters, friction parameters and friction state. The friction state and friction parameters can be effectively estimated at the same time, effectively reducing the estimation error of the servo electric cylinder system.

[0106] The method of the embodiment of the present invention can be applied to a terminal, or to a server, or can be software running in a terminal or a server. The terminal can be a tablet computer, a laptop computer, a desktop computer, etc., but is not limited thereto. The server can be an independent physical server, or a server cluster or a distributed system composed of multiple physical servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms.

[0107] In the embodiment of the present invention, the electric cylinder system model includes a friction model and an electric cylinder dynamics model. As a more specific embodiment, the modeling process of the electric cylinder system model of the present invention is described below:

[0108] (1) Friction model:

[0109] The friction model includes static friction model and dynamic friction model.

[0110] The static friction model includes the following equation:

[0111] F f1 =F c sgn(w)+F v w;

[0112] Among them, F c represents the steady-state value associated with the friction state z, F v represents the steady-state value associated with the viscous friction coefficient α'2, and w represents the speed of the servo electric cylinder motor.

[0113] The dynamic friction model is obtained by improving the static friction model based on the LuGre friction model; the LuGre friction model includes the following formulas:

[0114]

[0115] Among them, σ0 represents the bristle stiffness of the servo electric cylinder, which is abstracted from the LuGre friction model, σ1 represents the damping coefficient of the servo electric cylinder, which is abstracted from the LuGre friction model, α'2 represents the viscous friction coefficient of the servo electric cylinder, which is abstracted from the LuGre friction model, z represents the friction state of the servo electric cylinder, which is abstracted from the LuGre friction model, β0 represents the friction parameter of the servo electric cylinder, σ0α0 represents the Coulomb friction of the servo electric cylinder, σ0(α0+α1) represents the static friction of the servo electric cylinder, which is abstracted from the LuGre friction model, vs Indicates the stribeck speed;

[0116] As a preferred embodiment, a switching function s(|w|) is introduced into the LuGre dynamic friction model, so that the LuGre dynamic friction model and the traditional static friction model can be converted to each other according to the different states of the motor speed w.

[0117] The switching function s(|w|) is expressed as follows:

[0118]

[0119] Among them, g1 represents the upper threshold, and g2 represents the lower threshold;

[0120] The dynamic friction model is expressed as:

[0121]

[0122] (2) Dynamic model of electric cylinder:

[0123] Based on Newton's second law, the dynamic model of the electric cylinder is established according to the torque balance equation of the servo electric cylinder. The torque balance equation is as follows:

[0124]

[0125] Where J represents the moment of inertia of the servo electric cylinder, θ represents the rotation angle of the servo electric cylinder motor, the superscript “·” represents the derivative, the superscript “··” represents the second-order derivative, T e Indicates the electromagnetic torque of the servo electric cylinder motor, F f Indicates the friction torque of the servo electric cylinder motor, T l Indicates the load force of the servo electric cylinder motor;

[0126] T r =K h T l , P represents the lead of the servo electric cylinder.

[0127] Define x1 = θ, which represents the rotation angle of the servo electric cylinder motor. represents the speed of the servo electric cylinder motor; then the torque balance equation of the servo electric cylinder can be expressed as:

[0128]

[0129] Among them, K p represents the input torque ratio, and u represents the given current signal input.

[0130] The rotation angle x1 of the servo electric cylinder motor is directly proportional to the lead P of the servo electric cylinder:

[0131] y=Px1; therefore, the embodiment of the present invention can represent the trajectory state of the electric cylinder through x1 without observing the lead of the electric cylinder.

[0132] because Therefore, the electric cylinder system model is expressed as:

[0133]

[0134] make The electric cylinder system model is simplified to:

[0135]

[0136] Next, the observer design process of the present invention is described:

[0137] (1) Motion State Predictor

[0138] The motion state predictor is expressed as follows:

[0139]

[0140] Where λ represents the design parameter of the motion state predictor, λ>0; the superscript “^” represents the estimated value, and the superscript “~” represents the error value; therefore is the estimate of x1, is an estimate of x2.

[0141] Then the motion state prediction error is:

[0142]

[0143] ε represents the sliding mode function, which is expressed in the following form:

[0144]

[0145] (2) Friction state observer

[0146] The friction state observer in the embodiment of the present invention is a dual observer structure, which observes the friction state z in the friction model and obtains z0 and z1 as respective friction state estimation values; the friction state observer is expressed by the following formula:

[0147]

[0148] Among them, r1 and r2 represent the design parameters of the friction state observer, r1>0, r2>0;

[0149] l1 and l2 are robust terms, expressed in the following form:

[0150]

[0151] The superscript “^” indicates an estimated value, and the superscript “~” indicates an error value;

[0152] is the estimated value of the friction parameter β0.

[0153] The friction state estimation error includes:

[0154]

[0155] The friction state estimation error update law is expressed as follows:

[0156]

[0157] Then the parameter estimation part of the present invention is explained: the adaptive estimation of linear system parameters, friction parameters and friction state in the embodiment of the present invention is divided into two parts, the first part is the adaptive processing of linear system parameters; the second part is the adaptive estimation of friction parameters.

[0158] (1) Linear system parameter estimation

[0159] In the embodiment of the present invention, the linear system parameters include γ1, γ5 and γ7. By introducing the motion state prediction value and the motion state prediction error, the linear system parameter adaptive law can be designed to be expressed in the following form:

[0160]

[0161]

[0162] Among them, η1>0, η5>0, η7>0, k1>0, k5>0, k7>0 are all adaptive gains.

[0163] (2) Friction parameter estimation

[0164] In the embodiment of the present invention, the friction parameters determined include γ2, γ3, γ2, γ6 and β0; by introducing the motion state prediction error, the friction state estimation value and the friction state estimation error, the friction parameter adaptive law can be designed to be expressed in the following form:

[0165]

[0166] Among them, η2>0, η3>0, η4>0, η6>0, η8>0, k2>0, k3>0, k4>0, k6>0, k8>0 are all adaptive gains.

[0167] Finally, the friction state observer is adaptively optimized using the friction parameter estimation value; the motion state predictor is adaptively optimized using the linear system parameter estimation value, the friction state estimation value and the friction parameter estimation value. This makes the estimation of the linear system parameters, friction parameters and friction state in the embodiment of the present invention close to the actual friction effect of the servo electric cylinder.

[0168] As a more specific example, according to the formulas in the above steps, the servo electric cylinder system, LuGre dynamic friction model, electric cylinder dynamics model, motion state predictor, friction state observer, and the above parameter adaptive law and state estimation law are installed in Simulink software. The servo electric cylinder system and the motion state predictor have the same input sinusoidal current signal, the input of the dynamic friction model is the output of the motion state predictor, and the parameters used in the observer model are The friction state and friction parameters in the friction state observer model are also obtained by the adaptive estimation law and the parameter adaptive law. Comparing the motion state prediction value output by the motion state predictor with the motion state measurement value output by the actual servo electric cylinder system model, a curve diagram of the predicted motion state and the actual motion state can be obtained as shown in the figure below: Figure 4 As shown. It can be found Figure 4 The predicted motion state and the actual motion state are highly consistent, achieving a good fitting effect. The comparison between the observed friction states z0, z1 and β0 and the actual friction states is as follows Figure 5-7 As shown. Figure 5-7 The simulation results show that the friction force estimation value of the friction force model of the embodiment of the present invention gradually approaches the actual friction force value of the servo electric cylinder system in the continuous adaptive optimization. It can be seen that the unknown friction force state and parameters in the electric cylinder model can be estimated based on the method of the embodiment of the present invention, thereby realizing accurate prediction of the motion state of the servo electric cylinder with nonlinear friction and realizing accurate nonlinear friction compensation.

[0169] Simulation parameter setting reference: adaptive rate gain η1=0.1, η2=0.1, η3=1, η4=1, η5=2, η6=1, η7=4, η8=0.12, k1=1, k2=1, k3=0.1, k4=1, k5=1, k6=1, k7=1.5, k=99999, simulation system input reference: u=0.2sin(2πt)A.

[0170] The present invention discloses a method for simultaneously estimating the friction parameters and state of an electric cylinder, wherein the method comprises improving a traditional LuGre friction model to construct a dynamic friction model; using the dynamic friction model in combination with an electric cylinder dynamics model to simulate a servo electric cylinder system model; constructing a motion state predictor to predict the motion state of the servo electric cylinder system (including a motor angle and a motor speed), constructing a friction state observer to estimate the friction state of the servo electric cylinder system, and simultaneously adaptively processing the linear system parameters and friction parameters in the observer model, thereby realizing simultaneous estimation of the linear system parameters, friction parameters and friction state, and can be widely used in the field of engineering technology.

[0171] Figure 8 It is a schematic diagram of the structure of the electronic device proposed in the second embodiment of the present invention. The memory of this embodiment stores program instructions for implementing the method for simultaneously estimating the friction parameters and states of the electric cylinder of any of the above embodiments. The processor is used to execute the program instructions stored in the memory to simultaneously estimate the friction parameters and states of the electric cylinder. Among them, the processor can also be called CPU (Central Processing Unit). The processor may be an integrated circuit chip with signal processing capabilities. The processor can also be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc.

[0172] The contents of the method in the first embodiment of the present invention are all applicable to the electronic device embodiment. The functions specifically implemented by the electronic device embodiment are the same as those of the above method embodiment, and the beneficial effects achieved are also the same as those achieved by the above method.

[0173] Fig. 9It is a schematic diagram of the structure of the computer-readable storage medium of the third embodiment of the present invention. The computer-readable storage medium of the fourth embodiment of the present invention stores program instructions that can implement the above-mentioned method for simultaneously estimating the friction force parameters and state of the electric cylinder, wherein the program instructions can be stored in the above-mentioned storage medium in the form of a software product, including a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) or a processor (processor) to execute all or part of the steps of the methods of various embodiments of the present invention. The aforementioned computer-readable storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks or optical disks, or terminal devices such as computers, servers, mobile phones, and tablets.

[0174] The contents of the method in the first embodiment of the present invention are all applicable to the computer-readable storage medium embodiment. The functions specifically implemented by the computer-readable storage medium embodiment are the same as those of the above method embodiment, and the beneficial effects achieved are also the same as those achieved by the above method.

[0175] This embodiment also provides a computer program product. When the computer program product is run on a computer, the computer is caused to execute the above-mentioned related steps to implement the method for simultaneously estimating the friction force parameters and state of the electric cylinder provided in the above-mentioned embodiment.

[0176] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in the embodiments of the present invention are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data need to comply with the relevant laws, regulations and standards of relevant countries and regions, and provide corresponding operation entrances for users to choose to authorize or refuse.

[0177] Those skilled in the art will appreciate that the modules in the devices in the embodiments of the present invention may be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments of the present invention may be combined into one module or unit or component, and in addition they may be divided into a plurality of submodules or subunits or subcomponents. Except that at least some of such features and / or processes or units are mutually exclusive, all features disclosed in this specification (including corresponding claims, abstracts and drawings) and all processes or units of any method or device disclosed in this manner may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including corresponding claims, abstracts and drawings) may be replaced by an alternative feature providing the same, equivalent or similar purpose.

[0178] Through the description of the above implementation methods, technical personnel in the relevant field can understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0179] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0180] In addition, each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. In particular, for embodiments such as devices and equipment, since they are basically similar to method embodiments, the relevant parts can refer to the partial description of the method embodiments. The embodiments of the devices and equipment described above are merely schematic, wherein the modules, units, etc. described as separate components may or may not be physically separated, that is, they may be located in one place, or they may be distributed in multiple places, such as nodes of a system network. Specifically, some or all of the modules and units may be selected according to actual needs to achieve the purpose of the above-mentioned embodiment scheme. Those skilled in the art can understand and implement it without paying creative labor.

[0181] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0182] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0183] In addition, the terms "first", "second", etc. used in the embodiments of the present invention are only used for descriptive purposes and should not be understood as indicating or implying relative importance, or implicitly indicating the number of technical features indicated in the present embodiment. Therefore, the features defined by the terms "first", "second", etc. in the embodiments of the present invention can explicitly or implicitly indicate that the embodiment includes at least one of the features. In the description of the present invention, the word "multiple" means at least two or two or more, such as two, three, four, etc., unless otherwise clearly and specifically defined in the embodiments.

[0184] In the embodiments of the present invention, the terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element. In addition, components, features, and elements with the same name in different embodiments of the present invention may have the same meaning or different meanings, and their specific meanings need to be determined by their explanation in the specific embodiment or further combined with the context in the specific embodiment.

[0185] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and cannot be construed as limitations of the present invention, and those of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present invention. Those skilled in the art will readily come to think of other embodiments of the present invention after considering the specification and practicing the present invention. This application is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art that are not disclosed in the present invention. The specification and embodiments are intended to be exemplary only, and the true scope and spirit of the present invention are indicated by the following claims.

Claims

1. A method for simultaneously estimating friction parameters and states of an electric cylinder, characterized in that: It includes linear system parameter estimation part and friction state estimation and parameter estimation part; The linear system parameter estimation part includes the following steps: Establishing a dynamic model of the servo electric cylinder system according to its dynamic characteristics, and designing a motion state predictor based on the electric cylinder system model; The motion state of the servo electric cylinder system is measured by a photoelectric encoder to obtain a motion state measurement value, and a motion state prediction value is obtained by means of the motion state predictor; Subtracting the motion state measurement value from the motion state prediction value to obtain a motion state prediction error; Designing a linear system parameter adaptive law in combination with the motion state prediction value and the motion state prediction error to obtain a linear system parameter estimation value; The friction state estimation and parameter estimation part includes the following steps: Decomposing the electric cylinder system model to obtain a friction model, and designing a friction state observer based on the friction model; Inputting the motion state prediction value into the friction state observer to obtain a friction state estimation value; Designing a friction state estimation error update law in combination with the motion state prediction error to obtain a friction state estimation error; A friction parameter adaptive law is designed in combination with the friction force state estimation value and the friction force state estimation error to obtain the friction force parameter estimation value.

2. The method for simultaneously estimating friction parameters and states of an electric cylinder according to claim 1, characterized in that: The electric cylinder system model includes a friction model and an electric cylinder dynamics model; Wherein, the friction force model includes a static friction force model and a dynamic friction force model; The static friction model includes the following formula: F f1 =F c sgn(w)+F v w; Among them, F c represents the steady-state value associated with the friction state z, F v represents the steady-state value associated with the viscous friction coefficient α'2, and w represents the speed of the servo electric cylinder motor; The dynamic friction model is obtained by improving the static friction model based on the LuGre friction model; the LuGre friction model includes the following formula: Among them, σ0 represents the bristle stiffness of the servo electric cylinder, which is abstracted from the LuGre friction model, σ1 represents the damping coefficient of the servo electric cylinder, which is abstracted from the LuGre friction model, α'2 represents the viscous friction coefficient of the servo electric cylinder, which is abstracted from the LuGre friction model, z represents the friction state of the servo electric cylinder, which is abstracted from the LuGre friction model, β0 represents the friction parameter of the servo electric cylinder, σ0α0 represents the Coulomb friction of the servo electric cylinder, σ0(α0+α1) represents the static friction of the servo electric cylinder, which is abstracted from the LuGre friction model, v s Indicates the stribeck speed; Introducing a switching function s(|w|) into the LuGre friction model to obtain the dynamic friction model; The switching function s(|w|) is expressed in the following form: Among them, g1 represents the upper threshold, and g2 represents the lower threshold; The dynamic friction model is expressed as: The electric cylinder dynamics model is established according to the torque balance equation of the servo electric cylinder. The torque balance equation is as follows: Where J represents the moment of inertia of the servo electric cylinder, θ represents the rotation angle of the servo electric cylinder motor, the superscript "·" represents the derivative, the superscript "··" represents the second-order derivative, T e Indicates the electromagnetic torque of the servo electric cylinder motor, F f Indicates the friction torque of the servo electric cylinder motor, T l Indicates the load force of the servo electric cylinder motor; T r =K h T l , P represents the lead of the servo electric cylinder; Define x1 = θ, which represents the rotation angle of the servo electric cylinder motor. represents the speed of the servo electric cylinder motor; then the torque balance equation of the servo electric cylinder can be expressed as: Among them, K p represents the input torque ratio, u represents the given current signal input, The rotation angle x1 of the servo electric cylinder motor is directly proportional to the lead P of the servo electric cylinder: y=Px1; because Therefore, the electric cylinder system model is expressed as: make Then the electric cylinder system model is simplified as:

3. The method for simultaneously estimating friction parameters and states of an electric cylinder according to claim 2, characterized in that: The motion state predictor is expressed in the following form: Wherein, λ represents the design parameter of the motion state predictor, λ>0; the superscript "^" represents the estimated value, and the superscript "~" represents the error value; Then the motion state prediction error is: ε represents the sliding mode function, which is expressed in the following form:

4. A method for simultaneously estimating friction parameters and states of an electric cylinder according to claim 3, characterized in that: The linear system parameters include γ1, γ5 and γ7; The linear system parameter adaptation law is expressed in the following form: Among them, η1>0, η5>0, η7>0, k1>0, k5>0, k7>0 are all adaptive gains.

5. The method for simultaneously estimating friction parameters and states of an electric cylinder according to claim 2, characterized in that: The friction state observer is a dual observer structure, which observes the friction state z in the friction model and obtains z0 and z1 as the respective friction state estimation values; the friction state observer is expressed by the following formula: Wherein, r1 and r2 represent the design parameters of the friction state observer, r1>0, r2>0; l1 and l2 are robust terms, expressed in the following form: The superscript "^" indicates an estimated value, and the superscript "~" indicates an error value; is the estimated value of the friction parameter β0.

6. The method for simultaneously estimating friction parameters and states of an electric cylinder according to claim 5, characterized in that: The friction state estimation error includes: The friction state estimation error update law is expressed as follows:

7. A method for simultaneously estimating friction parameters and states of an electric cylinder according to claim 6, characterized in that: The friction force parameters include γ2, γ3, γ2, γ6 and β0; The friction force parameter adaptive law is expressed in the following form: Among them, η2>0, η3>0, η4>0, η6>0, η8>0, k2>0, k3>0, k4>0, k6>0, k8>0 are all adaptive gains.

8. The method for simultaneously estimating friction parameters and states of an electric cylinder according to claim 1, characterized in that: The following steps are also included: Adaptively optimizing the friction state observer using the friction parameter estimate; The motion state predictor is adaptively optimized using the linear system parameter estimation value, the friction state estimation value and the friction parameter estimation value.

9. An electronic device, characterized in that: including a processor and a memory; The memory is used to store programs; The processor executes the program to implement a method for simultaneously estimating friction parameters and states of an electric cylinder as described in any one of claims 1-8.

10. A computer-readable storage medium, characterized in that: The storage medium stores a program, and the program is executed by a processor to implement a method for simultaneously estimating friction parameters and states of an electric cylinder according to any one of claims 1 to 8.

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