Articulated robot control method and system and articulated robot

Abstract

An articulated robot control method and system and an articulated robot. The control method comprises: establishing a single-articulated impedance control model on the basis of a dynamics model of a robot; determining a stiffness range of a single articulation on the basis of the single-articulated impedance control model, the cut-off frequency of a robot control system, and a critical damping condition; using the stiffness range to determine the maximum stiffness value of the single articulation and a corresponding damping value; establishing a multi-articulated impedance control model and a Cartesian impedance model on the basis of the dynamics model; obtaining an articulation control law on the basis of the multi-articulated impedance control model and the Cartesian impedance model; and on the basis of the articulation control law, using the maximum stiffness value of the single articulation and the corresponding damping value to perform optimal impedance control. Thus, the technical problem in the prior art that the accuracy is low when dynamic performance control is performed on a robot by using an impedance control method is solved, and the technical effect of improving the accuracy of controlling the robot is achieved.

Description

Multi-joint robot control method, system and multi-joint robot

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 4, 2024, with application number 202410240238.5. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to the field of robot control technology, and in particular to a multi-joint robot control method, system and multi-joint robot. Background Art

[0003] Currently, position-controlled robots are the most widely used. To meet the stringent compliance and safety requirements of collaborative robots and service robots, force-controlled robots have garnered significant attention. Force-controlled robots are more complex to control and exhibit high levels of nonlinearity. Currently, active compliance control technologies are relatively mature, with impedance / admittance control and force / position hybrid control being the most widely used.

[0004] Among force control algorithms, impedance control offers excellent compliance and is suitable for interactive situations. Impedance control is a strategy that adjusts the robot's impedance parameters to control its dynamic performance, thereby improving its performance and adaptability. In practical engineering, constant parameter adjustments are often necessary to achieve a working state. Therefore, determining the optimal stiffness and damping for impedance control becomes crucial for precise robot control.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a multi-joint robot control method, system and multi-joint robot, which solve the technical problem of low accuracy in the prior art when using impedance control method to control the dynamic performance of the robot.

[0007] The present invention provides a control method for a multi-joint robot, which is applied to a robot control system. The control method includes:

[0008] Establishing a single-joint impedance control model based on the robot dynamics model, wherein the single-joint impedance control model is used to characterize the relationship between joint angle error, moment of inertia, damping, stiffness, and torque in a joint of the robot;

[0009] Determining a stiffness range of a single joint based on the single joint impedance control model, a cutoff frequency of the robot control system, and a critical damping condition, wherein the critical damping condition refers to a damping ratio of 1;

[0010] Determining the maximum stiffness of a single joint and the corresponding damping value using the stiffness range;

[0011] A multi-joint impedance control model and a Cartesian impedance model are established based on the dynamic model, wherein the multi-joint impedance control model is used to characterize the relationship between joint angle errors, moment of inertia matrices, damping matrices, stiffness matrices, and torque vectors in multiple joints of the robot;

[0012] Obtaining a joint control law based on the multi-joint impedance control model and the Cartesian impedance model;

[0013] Based on the joint control law, optimal impedance control is performed using the maximum stiffness of a single joint and the corresponding damping value.

[0014] Furthermore, determining the stiffness range of a single joint based on the single joint impedance control model, the cutoff frequency of the robot control system, and the critical damping condition includes:

[0015] Determining a first relationship between the cutoff frequency and damping and stiffness based on the single-joint impedance control model, the cutoff frequency of the robot control system, and the critical damping condition;

[0016] The stiffness range of the single joint is determined based on the principle that the cutoff frequency is less than half of the sampling frequency and the first relationship.

[0017] Furthermore, determining a first relationship between the cutoff frequency and damping and stiffness based on the single-joint impedance control model, the cutoff frequency of the robot control system, and the critical damping condition includes:

[0018] Based on the single joint impedance control model, the cutoff frequency of the robot control system And the critical damping condition ζ=1 determines the first relationship between the cutoff frequency and stiffness Among them, w b is the cutoff frequency, the natural frequency Damping ratio D is the damping, K is the stiffness, and M is the moment of inertia.

[0019] Furthermore, determining the stiffness range of a single joint based on the principle that the cutoff frequency is less than half of the sampling frequency and the first relationship includes:

[0020] Get the delay time T of the robot control system 延迟 =T;

[0021] Using T 采样 =2T sample hold instead of T 延迟 =T delay link;

[0022] Based on the principle that the cutoff frequency is less than half of the sampling frequency, the second relationship between the cutoff frequency and the sampling frequency is determined as follows:

[0023] The stiffness range of a single joint is determined by using the second relationship and the first relationship as follows:

[0024] Furthermore, before establishing the single-joint impedance control model based on the robot dynamics model, the control method further includes:

[0025] Building a robot dynamics model Where q represents the joint angle vector, represents the joint angular velocity vector, represents the joint angular acceleration vector, M(q) represents the inertia matrix, represents the centrifugal force matrix, g(q) represents the gravity torque vector, τ represents the joint torque vector, τ ext represents the external torque vector.

[0026] Furthermore, establishing a single joint impedance control model based on the robot dynamics model includes:

[0027] The single-joint impedance control model is established based on the robot dynamics model: Where i is the joint number, represents the joint angle error, represents the joint angular velocity error, represents the joint angular acceleration error, M represents the moment of inertia, D represents the damping, and K represents the stiffness.

[0028] Furthermore, establishing a multi-joint impedance control model and a Cartesian impedance model based on the dynamic model includes:

[0029] A multi-joint impedance control model is established based on the dynamic model: in, represents the joint angle error vector, represents the joint angular velocity error vector, represents the joint angular acceleration error vector, M 矩阵 =diag(M1, ..., M n ), D 矩阵 =diag(D1, ..., D n ), K 矩阵 =diag(K1, ..., K n ), n is the total number of joints;

[0030] A Cartesian impedance model is established based on the dynamic model: in, represents the Cartesian pose error, J represents the Jacobian matrix, Λ(x)=J -T M 矩阵 (p)J -1 , D(x)=J -T D 矩阵 J -1 , represents the derivative of the Jacobian matrix, q represents the joint angle vector, represents the joint angular velocity, K(x)=J -T K 矩阵 J -1 , F ext Denotes the Cartesian external force vector, F ext =J -T τ ext .

[0031] Furthermore, obtaining a joint control law based on the multi-joint impedance control model and the Cartesian impedance model includes:

[0032] The joint control law is obtained based on the multi-joint impedance control model and the Cartesian impedance model: Among them, x d Represents the desired Cartesian pose.

[0033] The present application also provides a multi-joint robot control system, the control system comprising:

[0034] A single-joint model building unit, configured to build a single-joint impedance control model based on the robot dynamics model, wherein the single-joint impedance control model is used to characterize the relationship between joint angle error, moment of inertia, damping, stiffness, and torque in a joint of the robot;

[0035] a first parameter determination unit, configured to determine a stiffness range of a single joint based on the single joint impedance control model, a cutoff frequency of the robot control system, and a critical damping condition, wherein the critical damping condition refers to a damping ratio of 1;

[0036] a second parameter determination unit, configured to determine a maximum stiffness value of a single joint and a corresponding damping value using the stiffness range;

[0037] A multi-joint model establishment unit, configured to establish a multi-joint impedance control model and a Cartesian impedance model based on the dynamic model, wherein the multi-joint impedance control model is used to characterize the relationship between the joint angle error vector, the moment of inertia matrix, the damping matrix, the stiffness matrix, and the corresponding torque vector in multiple joints of the robot;

[0038] a control relationship determining unit, configured to obtain a joint control law based on the multi-joint impedance control model and the Cartesian impedance model;

[0039] The impedance control unit is used to perform optimal impedance control based on the joint control law and using the maximum stiffness of the single joint and the corresponding damping value.

[0040] An embodiment of the present application also provides a multi-joint robot, which includes the multi-joint robot control system described in any of the above embodiments.

[0041] The embodiments of the present application disclose a multi-joint robot control method, system and multi-joint robot. The control method includes establishing a single-joint impedance control model based on the robot dynamic model; determining the stiffness range of the single joint based on the single-joint impedance control model, the cutoff frequency of the robot control system and the critical damping condition; using the stiffness range to determine the maximum stiffness of the single joint and the corresponding damping value; establishing a multi-joint impedance control model and a Cartesian impedance model based on the dynamic model; obtaining a joint control law based on the multi-joint impedance control model and the Cartesian impedance model; based on the joint control law, performing optimal impedance control using the maximum stiffness of the single joint and the corresponding damping value, thereby solving the technical problem of low accuracy in the prior art when using the impedance control method to control the dynamic performance of the robot, and achieving the technical effect of improving the control accuracy of the robot.

[0042] This application analyzes the mass damping stiffness second-order system equivalent to impedance control to determine the stiffness and damping of the optimal impedance control under different working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG1 is a flow chart of a control method for a multi-joint robot provided in an embodiment of the present application;

[0044] FIG2 is a structural diagram of a multi-joint robot control system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the present application and are not intended to limit the present application. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions of the present application, not all of the structures.

[0046] It should be noted that the terms "first," "second," and so on in the specification, claims, and drawings of this application are used to distinguish different objects, rather than to limit a specific order. The following embodiments of this application can be implemented independently or in combination with each other, and this embodiment of the application does not impose specific limitations on this.

[0047] FIG1 is a flow chart of a control method for a multi-joint robot provided in an embodiment of the present application. The control method for the multi-joint robot is applied to a robot control system. As shown in FIG1 , the control method for the multi-joint robot specifically includes the following steps:

[0048] S101, establishing a single-joint impedance control model based on the robot dynamics model, wherein the single-joint impedance control model is used to characterize the relationship between the joint angle error, moment of inertia, damping, stiffness and corresponding torque in a joint of the robot.

[0049] Optionally, before establishing a single-joint impedance control model based on the robot dynamics model in S101, the control method further includes:

[0050] Building a robot dynamics model Where q represents the joint angle vector, represents the joint angular velocity vector, represents the joint angular acceleration vector, M(q) represents the inertia matrix, represents the centrifugal force matrix, g(q) represents the gravity torque vector, τ represents the joint torque vector, τ ext represents the external torque vector.

[0051] Optionally, S101, establishing a single-joint impedance control model based on the robot dynamics model specifically includes:

[0052] Establish a single joint impedance control model based on the robot dynamics model: Where i is the joint number, represents the joint angle error, represents the joint angular velocity error, represents the joint angular acceleration error, M represents the moment of inertia, D represents the damping, and K represents the stiffness.

[0053] S102 , determining a stiffness range of a single joint based on a single joint impedance control model, a cutoff frequency of a robot control system, and a critical damping condition, wherein the critical damping condition refers to a damping ratio of 1.

[0054] Specifically, for impedance control, when the damping ratio is less than 0, the system is unstable. When the damping ratio is greater than 0 and less than 1, the system overshoots. When the damping ratio is greater than 1, the system does not overshoot, but the larger the damping ratio, the slower the response. Therefore, to ensure that the system does not become unstable and overshoot, and still responds quickly, it is necessary to select a damping ratio of 1.

[0055] Optionally, S102, determining the stiffness range of a single joint based on the single joint impedance control model, the cutoff frequency of the robot control system, and the critical damping condition specifically includes:

[0056] Determining a first relationship between the cutoff frequency and damping and stiffness based on a single-joint impedance control model, a cutoff frequency of the robot control system, and a critical damping condition;

[0057] The stiffness range of a single joint is determined based on the principle that the cutoff frequency is less than half of the sampling frequency and the first relationship.

[0058] Specifically, determining the first relationship between the cutoff frequency and the damping and stiffness based on the single-joint impedance control model, the cutoff frequency of the robot control system, and the critical damping condition includes:

[0059] Based on the single joint impedance control model, the cutoff frequency of the robot control system And the critical damping condition ζ = 1 determines the first relationship between the cutoff frequency and damping and stiffness Among them, w b is the cutoff frequency, the natural frequency Damping ratio D is damping, K is stiffness, and M is moment of inertia.

[0060] in, Used to calculate the closed-loop cutoff frequency of the second-order mass-damping-stiffness system equivalent to impedance control. Since when the damping ratio ζ = 1, the second-order mass-damping-stiffness system (i.e., the above-mentioned robot control system) is in a critical damping state, overshoot will occur when ζ is less than 1, so ζ = 1 is taken as the critical damping condition, and the cutoff frequency w is used. b The calculation formula is used to calculate the first relationship between the cutoff frequency and damping and stiffness.

[0061] Specifically, based on the principle that the cutoff frequency is less than half of the sampling frequency and the first relationship, the stiffness range of a single joint is determined as follows:

[0062] Get the delay time T of the robot control system 延迟 =T; using T 采样 =2T sample hold instead of T 延 迟=T delay link; based on the principle that the cutoff frequency is less than half of the sampling frequency, the second relationship between the cutoff frequency and the sampling frequency is determined as follows: The stiffness range of a single joint is determined by using the second relationship and the first relationship:

[0063] Among them, for the robot control system, the transfer function of its delay link is: F 延迟 (s)=0dB∠(-360°fT 延迟 ), the sample-hold transfer function is: F S-H (s)≈0dB∠(-180°fT 采样 ); The approximation above is almost exact. In fact, its phase is accurate, but the gain deviates slightly at high frequencies. However, this deviation is usually small, only a few dB, and it is no longer necessary to analyze the system in order to obtain better accuracy at high frequencies. Therefore, T is used. 采样 =2T sample hold instead of T 延 迟 =T delay link, the impedance parameters are designed based on the principle that the cutoff frequency of the system is less than 1 / 2 of the sampling frequency, and the second relationship between the cutoff frequency and the sampling frequency is obtained as follows: Then the stiffness range of a single joint is obtained as:

[0064] S103, determining the maximum stiffness of a single joint and the corresponding damping value using the stiffness range;

[0065] Specifically, in order to keep the system stable and prevent overshoot, it is necessary to ensure that the damping ratio ζ is 1, then:

[0066] Therefore, the maximum stiffness and the corresponding damping value are:

[0067] S104, establishing a multi-joint impedance control model and a Cartesian impedance model based on the dynamic model, wherein the multi-joint impedance control model is used to characterize the relationship between the joint angle error, moment of inertia matrix, damping matrix, stiffness matrix and corresponding torque vector in multiple joints of the robot.

[0068] Optionally, S104, establishing a multi-joint impedance control model and a Cartesian impedance model based on the dynamic model specifically includes:

[0069] Establish a multi-joint impedance control model based on the dynamic model: in, represents the joint angle error vector, represents the joint angular velocity error vector, represents the joint angular acceleration error vector, M 矩阵 =diag(M1, ..., M n ), D 矩阵 =diag(D1, ..., D n ), K 矩阵 =diag(K1, ..., K n ), n is the total number of joints;

[0070] Establish a Cartesian impedance model based on the dynamic model: in, represents the Cartesian pose error, J represents the Jacobian matrix, Λ(x)=J -T M 矩阵 (p)J -1 , D(x)=J -T D 矩阵 J -1 , represents the derivative of the Jacobian matrix, q represents the joint angle vector, represents the joint angular velocity, K(x)=J -T K 矩阵 J -1 , F ext Denotes the Cartesian external force vector, F ext =J -T τ ext .

[0071] S105 , obtaining a joint control law based on the multi-joint impedance control model and the Cartesian impedance model.

[0072] Optionally, in S105, obtaining the joint control law based on the multi-joint impedance control model and the Cartesian impedance model specifically includes:

[0073] The joint control law is obtained based on the multi-joint impedance control model and the Cartesian impedance model: Among them, x d Represents the desired Cartesian pose.

[0074] S106 , based on the joint control law, optimal impedance control is performed using the maximum stiffness of a single joint and the corresponding damping value.

[0075] Specifically, after obtaining the joint control law, the maximum stiffness and corresponding damping value of each joint are used to control the robot's various joints to perform the corresponding movements. Since the maximum stiffness and corresponding damping values ​​are determined by the robot's control system under the current state, the maximum stiffness and corresponding damping values ​​ultimately obtained based on different working conditions can achieve optimal impedance control performance.

[0076] This application analyzes the second-order mass-damping-stiffness system equivalent to impedance control, determines the stiffness and damping of the optimal impedance control under different working conditions, and then performs optimal impedance control on the robot. It solves the technical problem of low accuracy in the existing technology when using the impedance control method to control the dynamic performance of the robot, and achieves the technical effect of improving the control accuracy of the robot.

[0077] FIG2 is a structural diagram of a multi-joint robot control system provided in an embodiment of the present application.

[0078] As shown in Figure 2, the multi-joint robot control system specifically includes:

[0079] A single-joint model building unit 21 is used to build a single-joint impedance control model based on the robot dynamics model, wherein the single-joint impedance control model is used to characterize the relationship between the joint angle error, moment of inertia, damping, stiffness and corresponding torque in a joint of the robot;

[0080] a first parameter determination unit 22 for determining a stiffness range of a single joint based on a single joint impedance control model, a cutoff frequency of a robot control system, and a critical damping condition, wherein the critical damping condition refers to a damping ratio of 1;

[0081] A second parameter determination unit 23 is used to determine the maximum stiffness of a single joint and the corresponding damping value using the stiffness range;

[0082] A multi-joint model building unit 24 is used to establish a multi-joint impedance control model and a Cartesian impedance model based on the dynamic model, wherein the multi-joint impedance control model is used to characterize the relationship between the joint angle error vector, the moment of inertia matrix, the damping matrix, the stiffness matrix and the corresponding torque vector in multiple joints of the robot;

[0083] a control relationship determination unit 25, configured to obtain a joint control law based on a multi-joint impedance control model and a Cartesian impedance model;

[0084] The impedance control unit 26 is used to perform optimal impedance control based on the joint control law and using the maximum stiffness of a single joint and the corresponding damping value.

[0085] Optionally, the first parameter determination unit 22 includes:

[0086] a relationship determination subunit, configured to determine a first relationship between the cutoff frequency and the damping and stiffness based on a single-joint impedance control model, a cutoff frequency of the robot control system, and a critical damping condition;

[0087] The stiffness range determination subunit is used to determine the stiffness range of a single joint based on the principle that the cutoff frequency is less than half of the sampling frequency and the first relationship.

[0088] Optionally, the relationship determination subunit is specifically configured to:

[0089] Based on the single joint impedance control model, the cutoff frequency of the robot control system And the critical damping condition ζ = 1 determines the first relationship between the cutoff frequency and damping and stiffness Among them, w b is the cutoff frequency, the natural frequency Damping ratio D is damping, K is stiffness, and M is moment of inertia.

[0090] Optionally, the stiffness range determination subunit is specifically configured to:

[0091] Get the delay time T of the robot control system 延迟 =T;

[0092] Using T 采样 =2T sample hold instead of T 延迟 =T delay link;

[0093] Based on the principle that the cutoff frequency is less than half of the sampling frequency, the second relationship between the cutoff frequency and the sampling frequency is determined as follows:

[0094] The stiffness range of a single joint is determined by using the second relationship and the first relationship:

[0095] Optionally, before the single-joint model building unit 21 builds the single-joint impedance control model based on the robot dynamics model, the control device further includes:

[0096] Dynamic model building unit, used to build the robot dynamic model Where q represents the joint angle vector, represents the joint angular velocity vector, represents the joint angular acceleration vector, M(q) represents the inertia matrix, represents the centrifugal force matrix, g(q) represents the gravity torque vector, τ represents the joint torque vector, τ ext represents the external torque vector.

[0097] Optionally, the single joint model building unit 21 is specifically configured to:

[0098] Establish a single joint impedance control model based on the robot dynamics model: Where i is the joint number, represents the joint angle error, represents the joint angular velocity error, represents the joint angular acceleration error, M represents the moment of inertia, D represents the damping, and K represents the stiffness.

[0099] Optionally, the multi-joint model building unit 24 is specifically configured to:

[0100] A multi-joint impedance control model is established based on the dynamic model: in, represents the joint angle error vector, represents the joint angular velocity error vector, represents the joint angular acceleration error vector, M 矩阵 =diag(M1, ..., M n ), D 矩阵 =diag(D1, ..., D n ), K 矩阵 =diag(K1, ..., K n ), n is the total number of joints;

[0101] A Cartesian impedance model is established based on the dynamic model: in, represents the Cartesian pose error, J represents the Jacobian matrix, Λ(x)=J -T M 矩阵 (p)J -1 , D(x)=J -T D 矩阵 J -1 , represents the derivative of the Jacobian matrix, q represents the joint angle vector, represents the joint angular velocity, K(x)=J -T K 矩阵 J -1 , F ext Denotes the Cartesian external force vector, F ext =J -T τ ext .

[0102] Optionally, the control relationship determining unit 25 is specifically configured to:

[0103] The joint control law is obtained based on the multi-joint impedance control model and the Cartesian impedance model: Among them, x d Represents the desired Cartesian pose.

[0104] The multi-joint robot control system provided in the embodiments of the present application can execute the control method of the multi-joint robot provided in any embodiment of the present application, and has functional modules and beneficial effects corresponding to the execution method.

[0105] An embodiment of the present application also provides a multi-joint robot, which includes the multi-joint robot control system in any of the above embodiments.

[0106] The multi-joint robot provided in the embodiment of the present application includes the multi-joint robot control system in the above embodiment. Therefore, the multi-joint robot provided in the embodiment of the present application also has the beneficial effects described in the above embodiment, which will not be repeated here.

[0107] In the description of the embodiments of this application, unless otherwise specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0108] Finally, it should be noted that the above are only preferred embodiments of the present application and the technical principles employed. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present application. Therefore, although the present application has been described in more detail through the above embodiments, the present application is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present application. The scope of the present application is determined by the scope of the appended claims.

Claims

1. A control method for a multi-joint robot, applied to a robot control system, the control method comprising: Establishing a single-joint impedance control model based on the robot dynamics model, wherein the single-joint impedance control model is used to characterize the relationship between joint angle error, moment of inertia, damping, stiffness, and corresponding torque in a joint of the robot; Determining a stiffness range of a single joint based on the single joint impedance control model, a cutoff frequency of the robot control system, and a critical damping condition, wherein the critical damping condition refers to a damping ratio of 1; Determining the maximum stiffness of a single joint and the corresponding damping value using the stiffness range; A multi-joint impedance control model and a Cartesian impedance model are established based on the dynamic model, wherein the multi-joint impedance control model is used to characterize the relationship between the joint angle error vector, the moment of inertia matrix, the damping matrix, the stiffness matrix and the corresponding torque vector in multiple joints of the robot; Obtaining a joint control law based on the multi-joint impedance control model and the Cartesian impedance model; Based on the joint control law, optimal impedance control is performed using the maximum stiffness of a single joint and the corresponding damping value.

2. The control method of the multi-joint robot according to claim 1, wherein: Determining the stiffness range of a single joint based on the single joint impedance control model, the cutoff frequency of the robot control system, and the critical damping condition includes: Determining a first relationship between the cutoff frequency and damping and stiffness based on the single-joint impedance control model, the cutoff frequency of the robot control system, and the critical damping condition; The stiffness range of the single joint is determined based on the principle that the cutoff frequency is less than half of the sampling frequency and the first relationship.

3. The control method of the multi-joint robot according to claim 2, wherein: Determining a first relationship between the cutoff frequency and damping and stiffness based on the single-joint impedance control model, the cutoff frequency of the robot control system, and the critical damping condition includes: Based on the single joint impedance control model, the cutoff frequency of the robot control system And the critical damping condition ζ=1 determines the first relationship between the cutoff frequency and stiffness Among them, w b is the cutoff frequency, the natural frequency Damping ratio D is the damping, K is the stiffness, and M is the moment of inertia.

4. The control method of the multi-joint robot according to claim 3, wherein: Determining the stiffness range of a single joint based on the principle that the cutoff frequency is less than half of the sampling frequency and the first relationship includes: Get the delay time T of the robot control system 延迟 =T; Using T 采样 =2T sample hold instead of T 延迟 =T delay link; Based on the principle that the cutoff frequency is less than half of the sampling frequency, the second relationship between the cutoff frequency and the sampling frequency is determined as follows: The stiffness range of a single joint is determined by using the second relationship and the first relationship as follows:

5. The control method of the multi-joint robot according to claim 1, before establishing the single-joint impedance control model based on the robot dynamics model, further comprising: Building a robot dynamics model Where q represents the joint angle vector, represents the joint angular velocity vector, represents the joint angular acceleration vector, M(q) represents the inertia matrix, represents the centrifugal force matrix, g(q) represents the gravity torque vector, τ represents the joint torque vector, τ ext represents the external torque vector.

6. The control method of the multi-joint robot according to claim 5, wherein: The single-joint impedance control model based on the robot dynamics model includes: The single-joint impedance control model is established based on the robot dynamics model: Where i is the joint number, represents the joint angle error, represents the joint angular velocity error, represents the joint angular acceleration error, M represents the moment of inertia, D represents the damping, and K represents the stiffness.

7. The control method of the multi-joint robot according to claim 6, wherein: Establishing a multi-joint impedance control model and a Cartesian impedance model based on the dynamic model includes: A multi-joint impedance control model is established based on the dynamic model: in, represents the joint angle error vector, represents the joint angular velocity error vector, represents the joint angular acceleration error vector, M 矩阵 =diag(M1, ..., M n ), D 矩阵 =diag(D1, ..., D n ), K 矩阵 =diag(K1, ..., K n ), n is the total number of joints; A Cartesian impedance model is established based on the dynamic model: in, represents the Cartesian pose error, J represents the Jacobian matrix, Λ(x)=J -T M 矩阵 (p)J -1 , D(x)=J -T D 矩阵 J -1 , represents the derivative of the Jacobian matrix, q represents the joint angle vector, represents the joint angular velocity, K(x)=J -T K 矩阵 J -1 , F ext Denotes the Cartesian external force vector, F ext =J -T τ ext .

8. The control method of the multi-joint robot according to claim 7, wherein: The joint control law obtained based on the multi-joint impedance control model and the Cartesian impedance model includes: The joint control law is obtained based on the multi-joint impedance control model and the Cartesian impedance model: Among them, x d Represents the desired Cartesian pose.

9. A multi-joint robot control system comprising: a single-joint model building unit, configured to build a single-joint impedance control model based on a robot dynamics model, wherein the single-joint impedance control model is used to characterize the relationship between joint angle error, moment of inertia, damping, stiffness, and torque in a joint of the robot; a first parameter determination unit configured to determine a stiffness range of a single joint based on the single joint impedance control model, a cutoff frequency of the robot control system, and a critical damping condition, wherein the critical damping condition refers to a damping ratio of 1; a second parameter determination unit, configured to determine a maximum stiffness value of a single joint and a corresponding damping value using the stiffness range; a multi-joint model establishment unit, configured to establish a multi-joint impedance control model and a Cartesian impedance model based on the dynamic model, wherein the multi-joint impedance control model is used to characterize the relationship between the joint angle error vector, the moment of inertia matrix, the damping matrix, the stiffness matrix and the torque vector in multiple joints of the robot; a control relationship determining unit, configured to obtain a joint control law based on the multi-joint impedance control model and the Cartesian impedance model; The impedance control unit is configured to perform optimal impedance control based on the joint control law and using the maximum stiffness of a single joint and the corresponding damping value.

10. A multi-joint robot comprising the multi-joint robot control system according to claim 9.

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