WO2022179131A1

WO2022179131A1 - Torque control method and apparatus, terminal device, and storage medium

Info

Publication number: WO2022179131A1
Application number: PCT/CN2021/124622
Authority: WO
Inventors: 赵文; 赵明国; 熊友军
Original assignee: 深圳市优必选科技股份有限公司
Priority date: 2021-02-24
Filing date: 2021-10-19
Publication date: 2022-09-01
Also published as: CN112987812A; CN112987812B

Abstract

Provided are a torque control method and apparatus, a terminal device, and a storage medium. The method comprises: establishing a nominal dynamics model of a series elastic actuator (S101); obtaining a real-time disturbance quantity by means of a disturbance observer according to the nominal dynamics model, a current value input by a motor at the current time point, and an output torque of the series elastic actuator at the current time point (S102); obtaining a feedforward dynamics model by means of a feedforward compensator according to the nominal dynamics model and a scaling coefficient of rotational inertia of the motor (S103); obtaining a feedforward compensation amount according to the feedforward dynamics model and a desired output torque of the series elastic actuator (S104); and obtaining a desired current value and outputting the desired current value to the motor according to the real-time disturbance quantity, the feedforward compensation amount, and an ideal current value obtained by means of a proportional-differential controller (S105). The dynamic response performance can be improved, the control precision and the robustness of external disturbance are ensured, the stability is improved, and an algorithm is simple.

Description

A torque control method, device, terminal equipment and storage medium

This application claims the priority of the Chinese Patent Application No. 202110206469.0, filed with the Chinese Patent Office on February 24, 2021, the entire contents of which are incorporated herein by reference.

technical field

The present application belongs to the technical field of Series Elastic Actuator (SEA), and in particular, relates to a torque control method, device, terminal device and storage medium.

Background technique

The series elastic drive technology is a force-controlled joint technology. It is realized by connecting elastic elements (springs, etc.) in series between the motor and the load. When the motor drives the load to move, the elastic element will be elastically deformed to generate elastic torque. The torque drives the movement of the load, and the magnitude of the elastic torque used to drive the load can be obtained by measuring the deformation of the elastic element. The elastic element improves the flexibility and impact resistance of the load, which makes the load easy to drive back and has natural passive safety characteristics; at the same time, the elastic moment is detected by detecting the deformation amount of the elastic element whose stiffness has been calibrated, which has a higher force guarantee. In addition, the storage and release of energy can be realized through elastic elements, and the efficiency of energy use can be improved. However, the introduction of the elastic element makes the stiffness of the series elastic driver significantly decrease, so that the force control bandwidth of the series elastic driver is obviously reduced compared with that of the rigid driver. In addition, since the elastic element decouples the motor from the load, its force control algorithm is more complicated. , and the load is more susceptible to disturbance, which affects the accuracy and robustness of torque control.

technical problem

In view of this, the embodiments of the present application provide a torque control method, device, terminal device and storage medium, so as to solve the problem that the force control algorithm of the series elastic drive in the prior art is complex, the load is more easily affected by disturbance, and the torque control is affected. issues of accuracy and robustness.

technical solutions

A first aspect of the embodiments of the present application provides a torque control method, including:

Build the nominal dynamics model of the series elastic drive;

Obtain the real-time disturbance amount through the disturbance observer according to the nominal dynamic model, the current value input by the motor at the current moment, and the output torque of the series elastic driver at the current moment;

Obtaining a feedforward dynamic model according to the nominal dynamic model and the scaling factor of the moment of inertia of the motor by a feedforward compensator;

obtaining a feedforward compensation amount according to the feedforward dynamic model and the expected output torque of the series elastic driver;

According to the real-time disturbance amount, the feedforward compensation amount and the ideal current value obtained by the proportional-derivative controller, a desired current value is obtained and output to the motor.

A second aspect of the embodiments of the present application provides a torque control device, including:

A model building unit for building a nominal dynamic model of the series elastic drive;

a disturbance observation unit, configured to obtain a real-time disturbance amount through the disturbance observer according to the nominal dynamics model, the current value input by the motor at the current moment, and the output torque of the series elastic driver at the current moment;

a feed-forward compensation unit, configured to obtain a feed-forward dynamic model according to the nominal dynamic model and the scaling factor of the rotational inertia of the motor through a feed-forward compensator; according to the feed-forward dynamic model and the series connection The expected output torque of the elastic driver is obtained, and the feedforward compensation amount is obtained;

A proportional-derivative unit, configured to obtain a desired current value and output it to the motor according to the real-time disturbance amount, the feedforward compensation amount and the ideal current value obtained by the proportional-derivative controller.

A third aspect of the embodiments of the present application provides a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, and also including a series elastic driver and a load, the The series elastic driver includes a motor and an elastic element, the series elastic driver is connected with the load, and the processor implements the steps of the method according to the first aspect of the embodiments of the present application when the processor executes the computer program.

A fourth aspect of the embodiments of the present application provides a computer-readable storage medium, where the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the first aspect of the embodiments of the present application is implemented steps of the method described.

In the torque control method provided by the first aspect of the embodiments of the present application, the nominal dynamics model of the series elastic driver is established; the disturbance observer is used to determine the nominal dynamics model, the current value input by the motor at the current moment, and the series elastic driver at the current moment. The real-time disturbance amount is obtained by the output torque; the feedforward dynamic model is obtained according to the scaling factor of the nominal dynamic model and the moment of inertia of the motor through the feedforward compensator; the expected output torque is obtained according to the feedforward dynamic model and the series elastic drive , obtain the feedforward compensation amount; according to the real-time disturbance amount, the feedforward compensation amount and the ideal current value obtained by the proportional derivative controller, obtain the desired current value and output it to the motor, which can improve the dynamic response performance and ensure Control accuracy and robustness to external disturbances, achieve better control effect, improve stability and simple algorithm.

It can be understood that, for the beneficial effects of the foregoing second aspect to the fourth aspect, reference may be made to the relevant descriptions in the foregoing first aspect, and details are not described herein again.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present application more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only for the present application. In some embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

1 is a schematic flowchart of a torque control method provided by an embodiment of the present application;

2 is a schematic diagram of a mathematical model of a disturbance observer provided by an embodiment of the present application;

3 is a schematic structural diagram of a torque control device provided by an embodiment of the present application;

FIG. 4 is a schematic structural diagram of a terminal device provided by an embodiment of the present application.

Embodiments of the present invention

In the following description, for the purpose of illustration rather than limitation, specific details such as a specific system structure and technology are set forth in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be practiced in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

It is to be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described feature, integer, step, operation, element and/or component, but does not exclude one or more other The presence or addition of features, integers, steps, operations, elements, components and/or sets thereof.

It will also be understood that, as used in this specification and the appended claims, the term "and/or" refers to and including any and all possible combinations of one or more of the associated listed items.

As used in the specification of this application and the appended claims, the term "if" may be contextually interpreted as "when" or "once" or "in response to determining" or "in response to detecting ". Similarly, the phrases "if it is determined" or "if the [described condition or event] is detected" may be interpreted, depending on the context, to mean "once it is determined" or "in response to the determination" or "once the [described condition or event] is detected. ]" or "in response to detection of the [described condition or event]".

In addition, in the description of the specification of the present application and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the description, and should not be construed as indicating or implying relative importance.

References in this specification to "one embodiment" or "some embodiments" and the like mean that a particular feature, structure or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, appearances of the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in other embodiments," etc. in various places in this specification are not necessarily All refer to the same embodiment, but mean "one or more but not all embodiments" unless specifically emphasized otherwise. The terms "including", "including", "having" and their variants mean "including but not limited to" unless specifically emphasized otherwise.

The torque control method provided by the embodiments of the present application can be applied to terminal devices such as robots, robotic arms, wearable devices, vehicle-mounted devices, augmented reality (AR)/virtual reality (VR) devices, and the like. The terminal device includes a processor, a series elastic driver, and a load. The processor is used to control the series elastic driver to drive the movement of the load. The embodiment of the present application does not limit the specific type of the terminal device. The robot may specifically be a service robot, an underwater robot, an entertainment robot, a military robot, an agricultural robot, etc. The embodiments of the present application do not impose any restrictions on the specific type of the robot. Depending on the type of terminal device, the type of load is also different. For example, when the terminal device is a robot, the load can be a movable joint of the robot.

As shown in FIG. 1 , the torque control method provided by the embodiment of the present application includes the following steps S101 to S105:

Step S101, establishing a nominal dynamic model of the series elastic drive.

In the application, the series elastic drive consists of a motor and an elastic element. Since the elastic element of the series elastic drive decouples the motor from the load, the nominal dynamic model of the series elastic drive consists of the dynamic model of the motor and the dynamic model of the load. Consists of two parts.

In one embodiment, step S101 includes:

According to the dynamic model of the motor and the dynamic model of the load, the nominal dynamic model of the series elastic drive is established.

In one embodiment, the expression of the dynamic model of the motor is:

Among them, J _m represents the moment of inertia of the motor, θ _m represents the rotation angle of the motor, B _m represents the damping term of the motor, K _s represents the stiffness of the elastic element, θ _l represents the rotation angle of the load, τ _dm represents the uncertainty factor of the motor, and τ _m represents the output torque of the motor.

In application, the relationship between the motor's output torque and the motor's input current is τ _m = βi, where β is the equivalent torque coefficient of the motor. The uncertain factors of the motor include Coulomb friction and the error of the motor's dynamic model.

In one embodiment, the expression of the dynamic model of the load is:

Among them, J _l represents the moment of inertia of the load, B _l represents the damping term of the load, and τ _ext represents the moment from the external environment that the load receives.

In one embodiment, the expression of the nominal kinetic model is:

τ _s (s)=K _s Δθ

Δθ=θ _m -θ _l

Wherein, P _n (s) represents the nominal dynamic model, i(s) represents the current value input by the motor, τ _s (s) represents the output torque of the series elastic driver, and β represents the motor’s output torque. Equivalent moment coefficient, s represents the complex variable in the Laplace transform, and Δθ represents the deformation amount of the elastic element.

In application, τ _s (s)=K _s Δθ is the elastic torque generated by the elastic element, that is, the output torque of the series elastic driver. Considering the ideal situation, ignoring the disturbance of the motor τ _dm (that is, the uncertainty factor of the motor) and the external force τ _ext on the load, when the load is fixed, the dynamic model of the motor and the dynamic model of the load can take the current as a series connection The input of the elastic drive, the elastic torque is the system open-loop transfer function P _n (s) of the series elastic drive (ie, the nominal dynamic model) of the output of the serial elastic drive. The parameters used to calculate the nominal dynamic model can be identified through the motor manual or the parameter identification algorithm, and are known parameters.

Step S102: Obtain a real-time disturbance amount through the disturbance observer according to the nominal dynamics model, the current value input by the motor at the current moment, and the output torque of the series elastic driver at the current moment.

As shown in FIG. 2 , a schematic diagram of the mathematical model of the disturbance observer is exemplarily shown; wherein, _Cff is the feedforward filter, _τref is the expected output torque, and PD is the proportional-differential controller (Proportional-differential, PD). ), i is the current value input by the motor, d is the disturbance to the system, P is the actual dynamic model of the system, SEA is the series elastic drive, P _n is the nominal dynamic model, and P _n ^-1 is the nominal dynamic The inverse model of the model, Q is the low-pass filter, DOB is the disturbance observer (Disturbance OBserver, DOB), τ _s is the output torque of the series elastic driver.

In the application, since the inverse model P _n ^-1 of the nominal dynamic model cannot be realized physically, a low-pass filter Q needs to be introduced, and the low-pass filter can be a second-order Butterworth (Butterworth) )filter.

In one embodiment, step S102 includes:

The filter model of the low-pass filter is established by the nominal dynamics model;

Obtaining an inverse model of the nominal dynamic model according to the nominal dynamic model by a disturbance observer;

The real-time disturbance amount is obtained according to the inverse model of the nominal dynamic model, the current value input by the motor at the current moment, the output torque of the series elastic driver at the current moment, and the filter model.

In one embodiment, the expression of the filter model is:

Wherein, Q(s) represents the filter model, s represents the complex variable in the Laplace transform, and ω _q represents the cutoff frequency of the low-pass filter.

In application, the filter model Q(s) is the equivalent mathematical model of the low-pass filter Q shown in FIG. 2 . The value of the cut-off frequency ω _q of the low-pass filter should be greater than the upper limit value of the force control bandwidth of the series elastic driver, and at the same time, it should be avoided that the value is too high to filter high-frequency noise as much as possible, so as to eliminate the influence of high-frequency noise, that is, , the cutoff frequency should be greater than the upper limit of the force control bandwidth of the series elastic driver and less than the frequency of high frequency noise.

In one embodiment, the expression of the real-time disturbance amount is:

in,

represents the disturbance amount, Q(s) represents the filter model, i ⁰ (s) represents the current value input by the motor at the current moment,

represents the inverse model of the nominal kinetic model,

Indicates the output torque of the series elastic driver at the current moment.

In the application, the output torque τ _s of the series elastic driver can be obtained from the calibrated stiffness K _s of the elastic element and the detected deformation value Δθ of the elastic element. According to Fig. 2, the current value i input by the motor at the current moment and the current value of the current The output torque τ _s of the series elastic driver at time, the estimated value of the real-time disturbance can be obtained

In the application, the real-time disturbance estimation value is

Compensated to the input of the series elastic driver, the output torque τ _s (s) of the equivalent series elastic driver can be expressed as:

When the real-time disturbance estimate is

When the frequency is lower than the cutoff frequency of the low-pass filter Q(s), Q(s)=1, the above formula can be simplified as:

τ _s (s)=P _n (s)i(s)

That is, the model of the series elastic drive is adjusted from the actual dynamic model P(s) to the nominal dynamic model _Pn (s), which isolates the influence of the disturbance amount d(s).

Step S103 , obtaining a feedforward dynamic model according to the nominal dynamic model and the scaling factor of the moment of inertia of the motor through a feedforward compensator.

In the application, in order to improve the dynamic performance of the series elastic drive, a _feedforward ^compensator based on the nominal dynamic model is introduced. The filter Q(s) is composed. Unlike the inverse model P _n ^-1 in the disturbance observer, P _ff ^-1 (s) contains a scaling factor α of the motor's moment of inertia such that the moment of inertia in the nominal dynamic model for feedforward is αJ _m . The value of α is 0<α<1, which can be set according to actual needs. The purpose of introducing α is to reduce the overcompensation caused by the feedforward of the nominal dynamic model, and at the same time suppress the resonance phenomenon caused by the elastic element.

In one embodiment, the expression of the feedforward dynamics model is:

Among them, P _ff (s) represents the feedforward dynamic model, α represents the scaling factor of the moment of inertia of the motor, β represents the equivalent torque coefficient of the motor, K _s represents the stiffness of the elastic element, and J _m represents the The moment of inertia of the motor, s represents the complex variable in the Laplace transform, and B _m represents the damping term of the motor.

Step S104: Obtain a feedforward compensation amount according to the feedforward dynamic model and the expected output torque of the series elastic driver.

In one embodiment, step S104 includes:

A feedforward compensation amount is obtained from the feedforward dynamics model, the expected output torque of the series elastic drive, and the filter model.

In one embodiment, the expression of the feedforward compensation amount is:

Among them, C _ff (s) represents the feedforward compensation amount,

represents the inverse model of the feedforward dynamics model, Q(s) represents the filter model, and τ _ref (s) represents the desired output torque of the series elastic drive.

Step S105: Obtain a desired current value and output it to the motor according to the real-time disturbance amount, the feedforward compensation amount, and the ideal current value obtained through the proportional-derivative controller.

In the application, in the torque control of the series elastic drive, a suitable feedback controller is required to stabilize the closed-loop system, and a proportional-derivative controller as shown in Figure 2 can be used. The ideal current value is the current value calculated by the proportional-derivative controller for output to the motor.

In one embodiment, the expression of the ideal current value is:

Among them, i _PD (s) represents the ideal current value, K _P represents the coefficient of the proportional link in the proportional-derivative controller, τ _ref (s) represents the expected output torque of the series elastic driver,

represents the output torque of the series elastic driver at the current moment, K _P represents the coefficient of the differential link in the proportional-derivative controller, τ _ref '(s) represents the derivative of the expected output torque of the series elastic driver,

Indicates the inverse of the output torque of the series elastic driver at the current moment.

In one embodiment, the expression of the desired current value is:

where i ¹ (s) represents the expected current value of the motor,

represents the real-time disturbance amount, C _ff (s) represents the feedforward compensation amount, and i _PD (s) represents the ideal current value.

The torque control method provided in the embodiment of the present application can stabilize the closed-loop system of the series elastic driver by using the proportional-differential controller; since the series elastic driver system will be affected by friction and external disturbance, the series The elastic actuator is normalized, which can realize the observation and compensation of the disturbance; in order to improve the dynamic performance of the series elastic actuator system, a feedforward compensator based on the nominal dynamic model is used, and in order to avoid the feedforward of the nominal dynamic model. Over-compensation, the scaling factor of the equivalent moment of inertia is introduced into the feedforward term; the control system consisting of the proportional derivative controller, the disturbance observer and the feedforward compensator can not only improve the dynamic response performance of the terminal equipment, but also It can ensure the control accuracy and robustness to external disturbances, and the disturbance observer and feedforward compensator are located in the inner loop of the control architecture of the terminal device, so that the control algorithm of the outer loop can achieve better control effects based on it. .

Embodiments of the present application further provide a torque control device, which is used to execute the steps in the above torque control method embodiments. The torque control device can be a virtual appliance in the terminal equipment, run by the processor of the terminal equipment, or it can be the terminal equipment itself.

As shown in FIG. 3 , the torque control device provided by the embodiment of the present application includes:

a model establishment unit 101, used to establish a nominal dynamic model of the series elastic drive;

A disturbance observation unit 102, configured to obtain a real-time disturbance amount through the disturbance observer according to the nominal dynamics model, the current value input by the motor at the current moment, and the output torque of the series elastic driver at the current moment;

A feed-forward compensation unit 103 is configured to obtain a feed-forward dynamic model according to the nominal dynamic model and the scaling coefficient of the moment of inertia of the motor through a feed-forward compensator; according to the feed-forward dynamic model and the The expected output torque of the series elastic driver is obtained, and the feedforward compensation amount is obtained;

The proportional-derivative unit 104 is configured to obtain a desired current value and output it to the motor according to the real-time disturbance amount, the feed-forward compensation amount and the ideal current value obtained by the proportional-derivative controller.

In application, each unit in the torque control device may be a software program unit, or may be implemented by different logic circuits integrated in the processor, or may be implemented by multiple distributed processors.

As shown in FIG. 4 , an embodiment of the present application further provides a terminal device 200 , including: at least one processor 201 (only one processor is shown in FIG. 4 ), a memory 202 , and a terminal device 200 stored in the memory 202 and available in at least one The computer program 203 running on the processor 201 further includes a series elastic driver 204 and a load 205. When the processor 201 executes the computer program 203, the steps in the above torque control method embodiments are implemented.

In applications, end devices may include, but are not limited to, memory, processors, serial elastic drives, and loads. Those skilled in the art can understand that FIG. 4 is only an example of a terminal device, and does not constitute a limitation on the terminal device. It may include more or less components than the one shown in the figure, or combine some components, or different components, such as It may also include input and output devices, network access devices, and the like.

In an application, the processor may be a central processing unit (Central Processing Unit, CPU), and the processor may also be other general-purpose processors, digital signal processors (Digital Signal Processors, DSP), application specific integrated circuits (Application Specific Integrated Circuits) , ASIC), off-the-shelf programmable gate array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

In application, the memory may be an internal storage unit of the terminal device in some embodiments, such as a hard disk or a memory of the terminal device. In other embodiments, the memory can also be an external storage device of the terminal device, for example, a plug-in hard disk equipped on the terminal device, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash memory Card (Flash Card), etc. Further, the memory may also include both an internal storage unit of the terminal device and an external storage device. The memory is used to store an operating system, application programs, a boot loader (Boot Loader), data, and other programs, such as program codes of computer programs, and the like. The memory may also be used to temporarily store data that has been or will be output.

It should be noted that the information exchange, execution process and other contents between the above-mentioned devices/units are based on the same concept as the method embodiments of the present application. For specific functions and technical effects, please refer to the method embodiments section. It is not repeated here.

Those skilled in the art can clearly understand that, for the convenience and brevity of the description, only the division of the above functional units is used for illustration. The internal structure of the device is divided into different functional units to complete all or part of the functions described above. Each functional unit in the embodiment may be integrated in one processing unit, or each unit may exist physically alone, or two or more units may be integrated in one unit, and the above-mentioned integrated units may be implemented in the form of hardware. , and can also be implemented in the form of software functional units. In addition, the specific names of the functional units are only for the convenience of distinguishing from each other, and are not used to limit the protection scope of the present application. For the specific working process of the units in the above system, reference may be made to the corresponding process in the foregoing method embodiments, and details are not described herein again.

An embodiment of the present application provides a computer-readable storage medium, where the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, implements the torque control method of any of the foregoing embodiments.

The embodiments of the present application provide a computer program product, which, when the computer program product runs on a terminal device, enables the terminal device to execute the torque control method of any one of the foregoing embodiments.

The integrated unit, if implemented as a software functional unit and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on this understanding, the present application realizes all or part of the processes in the methods of the above-mentioned embodiments, which can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and the computer program is stored in a computer-readable storage medium. When executed by the processor, the steps of the foregoing method embodiments may be implemented. Wherein, the computer program includes computer program code, and the computer program code may be in the form of source code, object code, executable file or some intermediate forms, and the like. The computer-readable medium may include at least: any entity or device capable of carrying the computer program code to the terminal device, recording medium, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access memory) Memory), electrical carrier signals, telecommunications signals, and software distribution media. For example, U disk, mobile hard disk, disk or CD, etc.

In the foregoing embodiments, the description of each embodiment has its own emphasis. For parts that are not described or described in detail in a certain embodiment, reference may be made to the relevant descriptions of other embodiments.

Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of this application.

In the embodiments provided in this application, it should be understood that the disclosed apparatus, terminal device and method may be implemented in other manners. For example, the above-described embodiments of the apparatus and terminal device are only illustrative. For example, the division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined. Either it can be integrated into another system, or some features can be omitted, or not implemented. On the other hand, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical, mechanical or other forms.

The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The recorded technical solutions are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application, and should be included in the application. within the scope of protection.

Claims

A torque control method, comprising:

Build the nominal dynamics model of the series elastic drive;

Obtain the real-time disturbance amount through the disturbance observer according to the nominal dynamic model, the current value input by the motor at the current moment, and the output torque of the series elastic driver at the current moment;

Obtaining a feedforward dynamic model according to the nominal dynamic model and the scaling factor of the moment of inertia of the motor by a feedforward compensator;

obtaining a feedforward compensation amount according to the feedforward dynamic model and the expected output torque of the series elastic driver;

According to the real-time disturbance amount, the feedforward compensation amount and the ideal current value obtained by the proportional-derivative controller, a desired current value is obtained and output to the motor.
The torque control method according to claim 1, wherein the establishing a nominal dynamic model of the series elastic driver comprises:

According to the dynamic model of the motor and the dynamic model of the load, the nominal dynamic model of the series elastic drive is established.
The torque control method according to claim 2, wherein the expression of the dynamic model of the motor is:

Among them, J m represents the moment of inertia of the motor, θ m represents the rotation angle of the motor, B m represents the damping term of the motor, K s represents the stiffness of the elastic element, θ l represents the rotation angle of the load, τ dm represents the uncertainty factor of the motor, and τ m represents the output torque of the motor;

The expression of the dynamic model of the load is:

Wherein, J l represents the moment of inertia of the load, B l represents the damping term of the load, and τ ext represents the moment from the external environment that the load receives;

The expression of the nominal kinetic model is:

τ s (s)=K s Δθ

Δθ=θ m -θ l

Wherein, P n (s) represents the nominal dynamic model, i(s) represents the current value input by the motor, τ s (s) represents the output torque of the series elastic driver, and β represents the motor’s output torque. The equivalent moment coefficient, s represents the complex variable in the Laplace transform, and Δθ represents the deformation amount of the elastic element.
The torque control method according to claim 1, characterized in that, the disturbance observer obtains, according to the nominal dynamics model, the current value input by the motor at the current moment, and the output torque of the series elastic driver at the current moment, Real-time disturbance quantities, including:

The filter model of the low-pass filter is established by the nominal dynamics model;

Obtaining an inverse model of the nominal dynamic model according to the nominal dynamic model by a disturbance observer;

The real-time disturbance amount is obtained according to the inverse model of the nominal dynamic model, the current value input by the motor at the current moment, the output torque of the series elastic driver at the current moment, and the filter model.
The torque control method according to claim 4, wherein the expression of the filter model is:

Wherein, Q(s) represents the filter model, s represents the complex variable in the Laplace transform, and ω q represents the cutoff frequency of the low-pass filter;

The expression of the real-time disturbance amount is:

in,
represents the disturbance amount, Q(s) represents the filter model, i 0 (s) represents the current value input by the motor at the current moment,
represents the inverse model of the nominal kinetic model,
Indicates the output torque of the series elastic driver at the current moment.
The torque control method according to claim 1, wherein the expression of the feedforward dynamic model is:

Among them, P ff (s) represents the feedforward dynamic model, α represents the scaling factor of the moment of inertia of the motor, β represents the equivalent torque coefficient of the motor, K s represents the stiffness of the elastic element, and J m represents the The moment of inertia of the motor, s represents the complex variable in the Laplace transform, and B m represents the damping term of the motor.
The torque control method according to any one of claims 4 to 6, wherein the obtaining a feedforward compensation amount according to the feedforward dynamic model and the expected output torque of the series elastic driver comprises:

A feedforward compensation amount is obtained from the feedforward dynamics model, the expected output torque of the series elastic drive, and the filter model.
The torque control method according to claim 7, wherein the expression of the feedforward compensation amount is:

Among them, C ff (s) represents the feedforward compensation amount,
represents the inverse model of the feedforward dynamics model, Q(s) represents the filter model, and τ ref (s) represents the desired output torque of the series elastic drive.
The torque control method according to claim 1, wherein the expression of the desired current value is:

where i 1 (s) represents the desired current value of the motor,
represents the real-time disturbance amount, C ff (s) represents the feedforward compensation amount, and i PD (s) represents the ideal current value.
A torque control device, comprising:

A model building unit for building a nominal dynamic model of the series elastic drive;

a disturbance observation unit, configured to obtain a real-time disturbance amount through the disturbance observer according to the nominal dynamics model, the current value input by the motor at the current moment, and the output torque of the series elastic driver at the current moment;

a feed-forward compensation unit, configured to obtain a feed-forward dynamic model according to the nominal dynamic model and the scaling factor of the rotational inertia of the motor through a feed-forward compensator; according to the feed-forward dynamic model and the series connection The expected output torque of the elastic driver is obtained, and the feedforward compensation amount is obtained;

A proportional-derivative unit, configured to obtain a desired current value and output it to the motor according to the real-time disturbance amount, the feedforward compensation amount and the ideal current value obtained by the proportional-derivative controller.
A terminal device, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that it further comprises a series elastic drive connected to the processor, the series The elastic drive includes a motor and an elastic element, the series elastic drive is connected to a load, and the processor implements the steps of the method according to any one of claims 1 to 9 when executing the computer program.
A computer-readable storage medium storing a computer program, characterized in that, when the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 9 are implemented.