Robot force control method, device and equipment based on double encoders and medium

Abstract

The invention belongs to the field of robots, and provides a robot force control method, device and equipment based on double encoders and a medium, and the method comprises the steps: arranging the double encoders on the harmonic drive of a robot joint, and constructing the total error of the harmonic drive based on the kinematic error of a speed reducer and the deformation error of a flexible gear according to the readings of the double encoders; under the condition that the robot joints are not loaded, the kinematic error of the speed reducer is calculated according to the total error calculated through reading of the double encoders; establishing a fitting relational expression between the deformation error of the flexible gear and the estimated torque; controlling the robot joint to apply an output torque to the external load, and calculating an estimated torque output by the robot joint to the external load through the fitting relational expression, the kinematic error of the speed reducer and the read current readings of the double encoders; and the output torque is regulated and controlled in real time by estimating the torque through a closed-loop control algorithm. According to the method, the output torque can be effectively and accurately estimated, accurate regulation and control of the output torque can be realized, and the safety of the robot and the load is improved.

Description

Technical Field

[0001] The present invention belongs to the field of robots and relates to robot control technology, and in particular to a robot force control method, device, equipment and medium based on dual encoders. Background Art

[0002] Collaborative robots are robots specially designed to work with humans and ensure safety. With the needs of human production and life, the requirements for collaborative robots in contact work scenarios have increased, and they are required to have certain force perception capabilities. This force perception ability plays a very important role in contact operations and human-computer interaction safety.

[0003] Existing force sensing technologies are implemented in the following ways: (1) installing torque sensors at each joint; (2) using current to estimate torque; (3) installing strain gauges on the output shaft; (4) connecting elastic actuators in series; (5) installing six-dimensional force sensors at the end of the robot. These implementation methods have the following disadvantages: Although accurate force sensing can be achieved by installing torque sensors, the price of torque sensors is expensive, which increases the cost of use; the method of using current to estimate torque is simple, but it ignores the effects of friction and transmission errors, resulting in low force sensing ability and poor accuracy; due to the complex joint structure of collaborative robots and high production and manufacturing requirements, strain gauges need to be calibrated separately after production, and there is a problem of low position control accuracy, which increases the control error; the method of installing a six-dimensional force sensor at the end of the robot only enables the end to sense force, while the main body has no force sensing ability, so it cannot provide higher safety protection for human-machine collaboration.

[0004] In general, the existing force sensing implementation methods of collaborative robots have technical problems such as high cost, low control accuracy, and difficulty in providing high safety guarantees. Summary of the invention

[0005] In order to solve the technical problems of the existing collaborative robot force sensing implementation method, such as high cost, low control accuracy, and difficulty in providing high safety assurance, the present invention discloses a robot force control method based on a dual encoder, which includes the following steps:

[0006] S1. A dual encoder is provided on the harmonic drive of the robot joint, and a total error of the harmonic drive based on the motion error of the reducer and the deformation error of the flexspline is calculated according to the readings of the dual encoder;

[0007] S2. Under the condition that the robot joint is unloaded, calculating the total error according to the collected readings of the dual encoders, and calculating the reducer motion error according to the total error;

[0008] S3, establishing a fitting relationship between the flexspline deformation error and the estimated torque through the reducer motion error and the test torque;

[0009] S4, controlling the robot joint to apply an output torque to the external load, calculating a current total error by reading the current reading of the dual encoder, and calculating an estimated torque output by the robot joint to the external load by using the fitting relationship, the reducer motion error and the current total error;

[0010] S5. Using a closed-loop control algorithm, the output torque is regulated in real time using the estimated torque.

[0011] In an optional embodiment, in the above step S1, a dual encoder is set on the harmonic drive of the robot joint, and a total error of the harmonic drive based on the reducer motion error and the flexspline deformation error is calculated according to the readings of the dual encoder, including:

[0012] S11, setting a high-speed encoder at the high-speed end of the harmonic drive, setting a low-speed encoder at the low-speed end, using a first reading read from the high-speed encoder as the angle between the input end and the output end of the harmonic drive, and using a second reading read from the low-speed encoder as the angle of the robot joint;

[0013] S12, calculating the reducer motion error by using the flexspline position parameter, the reducer transmission ratio and the first reading, and calculating the flexspline deformation error by using the second reading and the flexspline position parameter;

[0014] S13. The sum of the reducer motion error and the flexspline deformation error is taken as the total error.

[0015] In an optional embodiment, in the above step S1, the calculation formula of the reducer motion error is: The calculation formula of the flexspline deformation error is: Δθ f =θ fo -θ fi , the calculation formula of the total error is in, is the reducer motion error, θ fi is the flexspline position parameter, θ w is the first reading, θ fo is the second reading, N is the gear ratio of the reducer; Δθ f is the flexspline deformation error, and Δθ is the total error.

[0016] In an optional embodiment, in the above step S2, under the condition that the robot joint is unloaded, the total error is calculated according to the collected readings of the dual encoder, and the reducer motion error is calculated according to the total error, including:

[0017] S21, when the robot joint is unloaded, controlling the robot joint to rotate one circle clockwise through the harmonic drive, and calculating the total clockwise motion error of the harmonic drive according to the collected readings of the dual encoders;

[0018] S22, when the robot joint is unloaded, controlling the robot joint to rotate counterclockwise for one circle through the harmonic drive, and calculating the total counterclockwise motion error of the harmonic drive according to the collected readings of the dual encoders;

[0019] S23. Calculate the average value of the total clockwise motion error and the total counterclockwise motion error to obtain the reducer motion error.

[0020] In an optional embodiment, in the above step S3, establishing a fitting relationship between the flexspline deformation error and the estimated torque through the reducer motion error and the test torque includes:

[0021] S31, fixing the high-speed end of the harmonic drive, applying multiple test torques to the robot joints through the low-speed end of the harmonic drive, and collecting the readings of the dual encoders under each test torque;

[0022] S32, calculating the total test error at each test torque according to the readings of the dual encoders at each test torque, and taking the difference between the reducer motion error and the total test error at each test torque as the flexible wheel deformation error at each test torque;

[0023] S33, using a differential evolution algorithm to perform three-segment linear fitting on all the test moments and their corresponding flexible wheel deformation errors to obtain the fitting relationship.

[0024] In an optional embodiment, in the above step S4, the output torque is applied to the robot joint, the current total error is calculated by reading the current reading of the dual encoder, and the estimated torque output by the robot joint to the external load is calculated using the fitting relationship, the reducer motion error and the current total error, including:

[0025] S41, controlling the robot joint to apply output torque to an external load through the harmonic drive, collecting current readings of the dual encoders, and calculating a current total error according to the current readings;

[0026] S42. According to the fitting relationship, the estimated torque output by the robot joint to the external load is calculated by using the reducer motion error and the current total error, wherein the calculation formula of the estimated torque is:

[0027] Among them, τ f1 is the estimated torque calculated under the output torque, is the reducer motion error, θ w is the first reading taken under output torque, θ fo is the second reading under output torque, N is the transmission ratio of the reducer; Δθ is the total error calculated under output torque, θ f1 is the difference between the first readings corresponding to the inflection point moment τ1 and the inflection point moment τ2 in the fitting relationship, θ f2 It is the difference between the second readings corresponding to the inflection point moment τ1 and the inflection point moment τ2 in the fitting relationship, and K1, K2, and K3 are the stiffnesses of the three curves in the fitting relationship respectively.

[0028] In an optional embodiment, the above step S4 further includes:

[0029] S43, comparing the current total error with the reducer motion error, when the current total error is less than or equal to the reducer motion error, formula τ f1 =K1b, where b is zero. When the current total error is greater than the reducer motion error, the formula τ f1 =K1b, where b is

[0030] An embodiment of the present invention also provides a robot force control device based on dual encoders, including a harmonic transmission model building module, a reducer motion error calculation module, a fitting relationship establishment module, an estimated torque calculation module and an output torque control module.

[0031] The harmonic drive model building module is used to set a dual encoder on the harmonic drive of the robot joint, and to calculate the total error of the harmonic drive based on the reducer motion error and the flexspline deformation error according to the readings of the dual encoder;

[0032] The reducer motion error calculation module is used to calculate the total error according to the collected readings of the dual encoders under the condition that the robot joint is unloaded, and calculate the reducer motion error according to the total error;

[0033] The fitting relationship establishing module is used to establish a fitting relationship between the flexspline deformation error and the estimated torque through the reducer motion error and the test torque;

[0034] The estimated torque calculation module is used to control the robot joint to apply an output torque to the external load, calculate the current total error by reading the current reading of the dual encoder, and calculate the estimated torque output by the robot joint to the external load by using the fitting relationship, the reducer motion error and the current total error;

[0035] The output torque control module is used to control the output torque in real time through the estimated torque by means of a closed-loop control algorithm.

[0036] An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements any of the above-mentioned robot force control methods based on dual encoders when executing the computer program, so as to solve the technical problems of existing collaborative robot force perception implementation methods, such as high cost, low control accuracy, and difficulty in providing high safety assurance.

[0037] An embodiment of the present invention also provides a computer-readable storage medium, which stores a computer program for executing any of the above-mentioned dual-encoder-based robot force control methods, so as to solve technical problems such as high cost, low control accuracy, and difficulty in providing high safety guarantees in existing collaborative robot force perception implementation methods.

[0038] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of this specification include at least: the robot force control method based on dual encoders of the present invention, first, by setting a dual encoder on the harmonic drive to construct a harmonic drive model, the total error of the harmonic drive based on the reducer motion error and the flexible wheel deformation error is designed to be calculated by using the readings of the dual encoders; then, the reducer motion error is calculated under no-load conditions, and the fitting relationship between the flexible wheel deformation error and the estimated torque is constructed by the reducer motion error and the test torque; finally, in the force control process under load conditions, the estimated torque is estimated by the fitting relationship, the reducer motion error and the current reading of the dual encoder read, and the output torque is regulated by the estimated estimated torque using a closed-loop control algorithm. The present invention estimates the torque of the robot joints through the dual encoders set on the harmonic drive of each joint, so that the robot has force perception capability, which can not only be applied to scenes with contact force requirements, but also ensure the safety of human-machine collaboration. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in 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 paying creative work.

[0040] Figure 1 A flowchart of a robot force control method based on dual encoders disclosed in an embodiment of the present invention;

[0041] Figure 2A schematic diagram of a harmonic drive model established by arranging dual encoders on a harmonic drive disclosed in an embodiment of the present invention;

[0042] Figure 3 is a fitting relationship curve between the flexspline deformation error and the estimated torque disclosed in an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of a robot force control device based on dual encoders disclosed in an embodiment of the present invention;

[0044] Figure 5 A schematic diagram of a computer device disclosed in an embodiment of the present invention;

[0045] Among them, 401, harmonic transmission model building module; 402, reducer motion error calculation module; 403, fitting relationship establishment module; 404, estimated torque calculation module; 405, output torque control module; 501, memory; 502, processor. DETAILED DESCRIPTION

[0046] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0047] The following describes the implementation methods of the present application through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and the features of the embodiments can be combined with each other in the absence of conflict. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0048] The embodiment of the present invention discloses a robot force control method based on dual encoders, see Figure 1 As shown, the method comprises the following steps:

[0049] S1. A dual encoder is provided on the harmonic drive of the robot joint, and a total error of the harmonic drive based on the motion error of the reducer and the deformation error of the flexspline is calculated according to the readings of the dual encoder, wherein the dual encoder readings include the angle of the robot joint and the angle between the input end and the output end of the harmonic drive;

[0050] S2. Under the condition that the robot joint is unloaded, calculating the total error according to the collected readings of the dual encoders, and calculating the reducer motion error according to the total error;

[0051] S3, establishing a fitting relationship between the flexspline deformation error and the estimated torque through the reducer motion error and the test torque;

[0052] S4, controlling the robot joint to apply an output torque to the external load, calculating a current total error by reading the current reading of the dual encoder, and calculating an estimated torque output by the robot joint to the external load by using the fitting relationship, the reducer motion error and the current total error;

[0053] S5. Using a closed-loop control algorithm, the output torque is regulated in real time using the estimated torque.

[0054] The estimated torque of each output torque is estimated by repeating steps S4 and S5, and the output torque is regulated by the estimated torque until the operation process of the robot joint on the external load is completed.

[0055] In an optional embodiment, in the above step S1, a dual encoder is set on the harmonic drive of the robot joint, and a total error of the harmonic drive based on the reducer motion error and the flexspline deformation error is calculated according to the readings of the dual encoder, including:

[0056] S11, a high-speed encoder is set at the high-speed end of the harmonic drive, and a low-speed encoder is set at the low-speed end, the first reading read from the high-speed encoder is used as the angle between the input end and the output end of the harmonic drive, and the second reading read from the low-speed encoder is used as the angle of the robot joint. The harmonic drive model established by setting dual encoders on the harmonic drive is shown in FIG. Figure 2 As shown in the figure, harmonic drive is a high-precision mechanical transmission system, whose core components include wave generator, flexspline and rigid wheel. The wave generator generates waves through rotation, causing the flexspline to deform and mesh with the rigid wheel, thereby achieving deceleration and high torque output. It has the characteristics of high precision, gapless transmission and high torque density, and is often used in application scenarios that require high precision and high reliability, such as robots and aerospace systems. Figure 2 The left side in the middle is the high-speed end of the harmonic drive, that is, the end where the wave generator is located, which can also be understood as the input end; the right side is the low-speed end of the harmonic drive, that is, the end where the flexible wheel is located, which can also be understood as the output end.

[0057] S12, calculating the reducer motion error according to the flexspline position parameter, the reducer transmission ratio and the first reading, and calculating the flexspline deformation error according to the second reading and the flexspline position parameter.

[0058] S13. The sum of the reducer motion error and the flexspline deformation error is taken as the total error.

[0059] Through the above steps S12 and S13, a calculation method for calculating the total error through the first reading, the second reading and the reducer transmission ratio can be obtained according to the calculation method of the reducer motion error and the flexible wheel deformation error. Specifically, in the above steps S12 and S13, the calculation formula of the reducer motion error is: The calculation formula of the flexspline deformation error is: Δθ f =θ fo -θ fi , the calculation formula of the total error is in, is the reducer motion error, θ fi is the flexspline position parameter, θ w is the first reading, θ fo is the second reading, N is the gear ratio of the reducer; Δθ f is the flexspline deformation error, and Δθ is the total error.

[0060] In an optional embodiment, in the above step S2, under the condition that the robot joint is unloaded, the total error is calculated according to the collected readings of the dual encoder, and the reducer motion error is calculated according to the total error, including:

[0061] S21, when the robot joint is unloaded, controlling the robot joint to rotate one circle clockwise through the harmonic drive, and calculating the total clockwise motion error of the harmonic drive according to the collected readings of the dual encoders;

[0062] S22. When the robot joint is unloaded, the robot joint is controlled to rotate counterclockwise for one circle by the harmonic drive, and the total counterclockwise motion error of the harmonic drive is calculated according to the collected readings of the dual encoders.

[0063] S23. Calculate the average value of the total clockwise motion error and the total counterclockwise motion error to obtain the reducer motion error.

[0064] In specific implementation, according to the calculation formula of total error, the total error Δθ of counterclockwise motion is cw It can be expressed as Total error Δθ of counterclockwise motion ccw It can be expressed as Since the total error is measured under no-load conditions, the flexspline deformation error Δθ f is zero, and when rotating clockwise and counterclockwise, the counterclockwise reducer motion error and clockwise reducer motion error satisfy Therefore, it can be obtained that when there is no load, the reducer motion error is Δθ ccwand Δθ cw The average value of Δθ ccw and Δθ cw The readings of the dual encoders during clockwise and counterclockwise rotation can be used to calculate the formula The calculation results in the value of the reducer motion error.

[0065] In an optional embodiment, in the above step S3, since the stiffness of the flexible pulley increases with the increase of the torsion angle and the hysteresis behavior, in order to be closer to the flexible pulley stiffness curve, the present invention uses three straight lines to approximate the relationship between the flexible pulley deformation error and the estimated torque. Specifically, the fitting relationship between the flexible pulley deformation error and the estimated torque is established by the reducer motion error and the test torque, including:

[0066] S31, fixing the high-speed end of the harmonic drive, applying multiple test torques to the robot joints through the low-speed end of the harmonic drive, and collecting the readings of the dual encoders under each test torque;

[0067] S32, calculating the total test error at each test torque according to the readings of the dual encoders at each test torque, and taking the difference between the reducer motion error and the total test error at each test torque as the flexible wheel deformation error at each test torque;

[0068] S33, using a differential evolution algorithm to perform three-segment linear fitting on all the test moments and their corresponding flexible wheel deformation errors to obtain the fitting relationship.

[0069] When the above step S31 is implemented, the test torque can be gradually increased from 0 to the rated torque, and the readings of the dual encoders (including the first reading and the second reading) are recorded for each test torque, and the data sets {test torque 1, first reading 1, second reading 1}, {test torque 2, first reading 2, second reading 2}, ..., {test torque n, first reading n, second reading n} can be obtained.

[0070] When the above step S33 is specifically implemented, a differential evolution algorithm may be used to perform three-segment linear fitting on the data set obtained in step S31, and the expression of the fitting relationship is obtained as follows: τ f To test the torque, K1, K2, and K3 are the stiffness of the three fitted curves, τ1 and τ2 are the inflection point torques, and Δθ f is the flexspline deformation error, where the fitting relationship curve between the flexspline deformation error and the estimated torque is as follows: Figure 3 shown.

[0071] In an optional embodiment, in the above step S4, an output torque is applied to the robot joint, a current total error is calculated by reading the current reading of the dual encoder, and an estimated torque output by the robot joint to the external load is calculated using the fitting relationship, the reducer motion error and the current total error, including:

[0072] S41, under load conditions, controlling the robot joint to apply output torque to the external load through the harmonic drive, collecting current readings of the dual encoders, and calculating a current total error according to the current readings;

[0073] S42. Calculate the estimated torque output by the robot joint to the external load through the reducer motion error and the current total error according to the fitting relationship.

[0074] In specific implementation, the calculation formula for the estimated torque can be obtained by fitting the relationship and the calculation formula for the total error:

[0075] Among them, τ f1 is the estimated torque calculated under the output torque, is the reducer motion error, θ w is the first reading taken under output torque, θ fo is the second reading under output torque, N is the transmission ratio of the reducer; Δθ is the total error calculated under output torque, θ f1 is the difference between the first readings corresponding to the inflection point moment τ1 and the inflection point moment τ2 in the fitting relationship, θ f2 It is the difference between the second readings corresponding to the inflection point moment τ1 and the inflection point moment τ2 in the fitting relationship, and K1, K2, and K3 are the stiffnesses of the three curves in the fitting relationship respectively.

[0076] In an optional embodiment, the above step S4 further includes:

[0077] S43, comparing the current total error with the reducer motion error, when the current total error is less than or equal to the reducer motion error, formula τ f1 =K1b, where b is zero. When the current total error is greater than the reducer motion error, the formula τ f1 =K1b, where b is

[0078] The robot force control method based on dual encoders of the present invention, firstly, constructs a harmonic drive model by setting dual encoders on the harmonic drive, designs to use the readings of the dual encoders to calculate the total error of the harmonic drive based on the reducer motion error and the flexwheel deformation error; then, calculates the reducer motion error under no-load conditions, and constructs a fitting relationship between the flexwheel deformation error and the estimated torque through the reducer motion error and the test torque; finally, in the force control process under load conditions, estimates the estimated torque through the fitting relationship, the reducer motion error and the current readings of the read dual encoders, and uses a closed-loop control algorithm to regulate the output torque through the estimated estimated torque. The present invention estimates the torque of the robot joints through the dual encoders set on the harmonic drive of each joint, so that the robot has force perception ability, which can not only be applied to scenes with contact force requirements, but also ensure the safety of human-machine collaboration.

[0079] Based on the same inventive concept, a robot force control device based on a dual encoder is also provided in an embodiment of the present invention, as described in the following embodiment. Since the principle of solving the problem by the robot force control device based on a dual encoder is similar to the above-mentioned robot force control method based on a dual encoder, the implementation of the robot force control device can refer to the implementation of the above-mentioned robot force control method, and the repeated parts will not be repeated. As used below, the term "unit" or "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0080] Figure 4 is a structural block diagram of a robot force control device based on dual encoders disclosed in an embodiment of the present invention, such as Figure 4 As shown, the device includes: a harmonic drive model building module 401, a reducer motion error calculation module 402, a fitting relationship establishment module 403, an estimated torque calculation module 404 and an output torque control module 405. The structure is described below.

[0081] The harmonic drive model building module 401 is used to set a dual encoder on the harmonic drive of the robot joint, and to calculate the total error of the harmonic drive based on the reducer motion error and the flexspline deformation error according to the readings of the dual encoder;

[0082] The reducer motion error calculation module 402 is used to calculate the total error according to the collected readings of the dual encoders under the condition that the robot joint is unloaded, and calculate the reducer motion error according to the total error;

[0083] The fitting relationship establishing module 403 is used to establish a fitting relationship between the flexspline deformation error and the estimated torque through the reducer motion error and the test torque;

[0084] The estimated torque calculation module 404 is used to control the robot joint to apply an output torque to the external load, calculate the current total error by reading the current reading of the dual encoder, and calculate the estimated torque output by the robot joint to the external load by using the fitting relationship, the reducer motion error and the current total error;

[0085] The output torque control module 405 is used to control the output torque in real time through the estimated torque by means of a closed-loop control algorithm.

[0086] In an optional embodiment, the fitting relationship establishment module 403 is used to fix the high-speed end of the harmonic transmission, apply multiple test torques to the robot joint through the low-speed end of the harmonic transmission, and collect the readings of the dual encoders at each test torque; calculate the total test error at each test torque according to the readings of the dual encoders at each test torque, and take the difference between the reducer motion error and the total test error at each test torque as the flexible wheel deformation error at each test torque; use the differential evolution algorithm to perform three-segment linear fitting on all the test torques and their corresponding flexible wheel deformation errors to obtain the fitting relationship.

[0087] In an optional embodiment, the estimated torque calculation module 404 is used to control the robot joint to apply an output torque to an external load through the harmonic drive, collect the current reading of the dual encoder, calculate the current total error according to the current reading, and calculate the estimated torque output by the robot joint to the external load through the reducer motion error and the current total error according to the fitting relationship, wherein the calculation formula of the estimated torque is:

[0088] Among them, τ f1 is the estimated torque calculated under the output torque, is the reducer motion error, θ w is the first reading taken under output torque, θ fo is the second reading under output torque, N is the transmission ratio of the reducer; Δθ is the total error calculated under output torque, θ f1 is the difference between the first readings corresponding to the inflection point moment τ1 and the inflection point moment τ2 in the fitting relationship, θ f2 It is the difference between the second readings corresponding to the inflection point moment τ1 and the inflection point moment τ2 in the fitting relationship, and K1, K2, and K3 are the stiffnesses of the three curves in the fitting relationship respectively.

[0089] In this embodiment, a computer device is provided, such as Figure 5 As shown, it includes a memory 501, a processor 502, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, any of the above-mentioned robot force control methods based on dual encoders is implemented.

[0090] Specifically, the computer device may be a computer terminal, a server or a similar computing device.

[0091] In this embodiment, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program for executing any of the above-mentioned robot force control methods based on dual encoders.

[0092] Specifically, computer-readable storage media include permanent and non-permanent, removable and non-removable media that can be used to store information by any method or technology. Information can be computer-readable instructions, data structures, program modules or other data. Examples of computer-readable storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable storage media does not include temporary computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0093] The embodiment of the present invention further provides a collaborative robot, the collaborative robot includes a harmonic drive located on each robot joint, the height end of the harmonic drive is provided with a height encoder, the low speed end is provided with a low speed encoder, the first reading read by the height encoder is used as the angle between the input end and the output end of the harmonic drive, and the second reading read by the low speed encoder is used as the angle of the corresponding robot joint. The collaborative robot also includes the above-mentioned memory, a processor, and a computer program stored in the memory and executable on the processor, and when the processor executes the computer program, the steps of the robot force control method shown in the above embodiment are implemented.

[0094] Obviously, those skilled in the art should understand that the modules or steps of the above-mentioned embodiments of the present invention can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and optionally, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order from that here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. In this way, the embodiments of the present invention are not limited to any specific combination of hardware and software.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A robot force control method based on dual encoders, characterized in that: include: A dual encoder is provided on the harmonic drive of the robot joint, and a total error of the harmonic drive based on the motion error of the reducer and the deformation error of the flexspline is calculated according to the readings of the dual encoder; Under the condition that the robot joint is unloaded, a total error is calculated according to the collected readings of the dual encoders, and a reducer motion error is calculated according to the total error; A fitting relationship between the flexspline deformation error and the estimated torque is established through the reducer motion error and the test torque; Control the robot joint to apply an output torque to an external load, calculate a current total error by reading a current reading of the dual encoder, and calculate an estimated torque output by the robot joint to the external load by using the fitting relationship, the reducer motion error and the current total error; The output torque is regulated in real time by the estimated torque through a closed-loop control algorithm.

2. The robot force control method based on dual encoders according to claim 1 is characterized in that: The method of setting a dual encoder on the harmonic drive of the robot joint and calculating the total error of the harmonic drive based on the reducer motion error and the flexspline deformation error according to the readings of the dual encoder comprises: A high-speed encoder is provided at the high-speed end of the harmonic drive, and a low-speed encoder is provided at the low-speed end, a first reading read from the high-speed encoder is used as the angle between the input end and the output end of the harmonic drive, and a second reading read from the low-speed encoder is used as the angle of the robot joint; The reducer motion error is calculated by the flexspline position parameter, the reducer transmission ratio and the first reading, and the flexspline deformation error is calculated by the second reading and the flexspline position parameter; The sum of the reducer motion error and the flexspline deformation error is taken as the total error.

3. The robot force control method based on dual encoders according to claim 2 is characterized in that: The calculation formula of the reducer motion error is: The calculation formula of the flexspline deformation error is: Δθ f =θ fo -θ fi , the calculation formula of the total error is in, is the reducer motion error, θ fi is the flexspline position parameter, θ w is the first reading, θ fo is the second reading, N is the gear ratio of the reducer; Δθ f is the flexspline deformation error, and Δθ is the total error.

4. The robot force control method based on dual encoders according to claim 1 is characterized in that: The method of calculating the total error according to the collected readings of the dual encoders under the condition that the robot joints are unloaded, and calculating the reducer motion error according to the total error, comprises: Under the condition that the robot joint is unloaded, the robot joint is controlled to rotate one circle clockwise by the harmonic drive, and the total clockwise motion error of the harmonic drive is calculated according to the collected readings of the dual encoders; Under the condition that the robot joint is unloaded, the robot joint is controlled to rotate counterclockwise by one circle through the harmonic drive, and the total counterclockwise motion error of the harmonic drive is calculated according to the collected readings of the dual encoders; The average value of the total clockwise motion error and the total counterclockwise motion error is calculated to obtain the reducer motion error.

5. The robot force control method based on dual encoders according to claim 1 or 4, characterized in that: The fitting relationship between the flexspline deformation error and the estimated torque is established by using the reducer motion error and the test torque, including: The high-speed end of the harmonic drive is fixed, a plurality of test torques are applied to the robot joint through the low-speed end of the harmonic drive, and the reading of the dual encoder under each test torque is collected; According to the readings of the dual encoders at each test torque, the total test error at each test torque is calculated, and the difference between the reducer motion error and the total test error at each test torque is used as the flexible wheel deformation error at each test torque; A differential evolution algorithm is used to perform three-segment linear fitting on all the test moments and the corresponding flexible wheel deformation errors to obtain the fitting relationship.

6. The robot force control method based on dual encoders according to claim 5 is characterized in that: The step of applying an output torque to the robot joint, calculating a current total error by reading a current reading of the dual encoder, and calculating an estimated torque output by the robot joint to an external load by using the fitting relationship, the reducer motion error, and the current total error includes: Controlling the robot joint to apply output torque to an external load through the harmonic drive, collecting current readings of the dual encoders, and calculating a current total error based on the current readings; According to the fitting relationship, the estimated torque output by the robot joint to the external load is calculated by the reducer motion error and the current total error, wherein the calculation formula of the estimated torque is: Among them, τ f1 is the estimated torque calculated under the output torque, is the reducer motion error, θ w is the first reading taken under output torque, θ fo is the second reading under output torque, N is the transmission ratio of the reducer; Δθ is the total error calculated under output torque, θ f1 is the difference between the first readings corresponding to the inflection point moment τ1 and the inflection point moment τ2 in the fitting relationship, θ f2 It is the difference between the second readings corresponding to the inflection point moment τ1 and the inflection point moment τ2 in the fitting relationship, and K1, K2, and K3 are the stiffnesses of the three curves in the fitting relationship respectively.

7. The robot force control method based on dual encoders according to claim 6 is characterized in that: Also includes: Compare the current total error with the reducer motion error. When the current total error is less than or equal to the reducer motion error, the formula τ f1 =K1b, where b is zero. When the current total error is greater than the reducer motion error, the formula τ f1 =K1b, where b is 8. A robot force control device based on dual encoders, characterized in that: include: A harmonic drive model building module, the harmonic drive model building module is used to set a dual encoder on the harmonic drive of the robot joint, and to calculate the total error of the harmonic drive based on the reducer motion error and the flexspline deformation error according to the readings of the dual encoder; A reducer motion error calculation module, wherein the reducer motion error calculation module is used to calculate a total error according to the collected readings of the dual encoders under the condition that the robot joint is unloaded, and calculate the reducer motion error according to the total error; A fitting relationship establishment module, wherein the fitting relationship establishment module is used to establish a fitting relationship between the flexspline deformation error and the estimated torque through the reducer motion error and the test torque; An estimated torque calculation module, the estimated torque calculation module is used to control the robot joint to apply an output torque to an external load, calculate a current total error by reading the current reading of the dual encoder, and calculate an estimated torque output by the robot joint to the external load using the fitting relationship, the reducer motion error and the current total error; An output torque control module is used to control the output torque in real time through the estimated torque by means of a closed-loop control algorithm.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the robot force control method based on dual encoders described in any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program for executing the robot force control method based on dual encoders according to any one of claims 1 to 7.

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