Control method for a robotic bilateral teleoperation system with time-varying time delay

Abstract

The application discloses a control method of a robot bilateral teleoperation system with time-varying time delay, and solves the technical problem of poor transparency and stability of the bilateral teleoperation system. The control method comprises the following steps: a master end time delay state observer outputs an estimated value of a slave robot joint position derivative affected by time-varying time delay; an integrator is used to obtain an estimated value of the slave robot joint position; a master end force estimation algorithm outputs an estimated value of the master end force; a master robot controller processes the estimated value of the slave robot joint position and the estimated value of the master end force, and obtains a control torque of the master robot controller; a slave end time delay state observer outputs an estimated value of a master robot joint position derivative affected by time-varying time delay; the integrator is used to obtain an estimated value of the master robot joint position; a slave end force estimation algorithm outputs an estimated value of the slave end force; and a slave robot controller obtains the estimated value of the master robot joint position and the estimated value of the slave end force, and processes to obtain a control torque of the slave robot controller.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of control of a robot teleoperation system, in particular to a control method of a robot bilateral teleoperation system with time-varying time delay. BACKGROUND

[0002] In a robot teleoperation system, an operator remotely operates a slave robot through a master robot to perform tasks in some special environments, such as radiation and hazardous material handling, underwater exploration, space operation and remote surgery, etc. The operator information is transmitted to the slave robot through the master robot, and the slave robot transmits the environmental information to the master robot, so that the operator obtains the interaction information of the slave robot and the remote environment. Since the information between the master and slave robots flows in both directions, this remote operation system is called a bilateral teleoperation system.

[0003] The bilateral teleoperation system requires that the slave robot can accurately track the joint position of the master robot, and the operator can truly feel the interaction force between the slave robot and the environment, so as to ensure the position tracking performance and force tracking performance of the system. Since there is inevitably a communication time delay when data is exchanged between the master and slave robots, the time delay is one of the complex practical problems that affect the tracking performance of the bilateral teleoperation system. For the teleoperation system control problem with constant time delay, scholars have conducted a lot of research, but the most common in the actual teleoperation system is not constant delay, but more is some time-varying delay. Therefore, the unknown external interaction force and the time-varying time delay are the main reasons for increasing the joint position and force tracking error between the master and slave robots, thereby reducing the transparency and stability of the teleoperation system.

[0004] In order to solve the problem of time-varying time delay of the teleoperation system, Chinese invention patent CN103831831A discloses a nonlinear teleoperation system position and force tracking control system with time-varying time delay, and discloses a position and force tracking control system with time-varying time delay to solve the problem of position and force error between the master and slave robots caused by transmission delay, but the patent has the constraint that the change rate of the time-varying time delay is less than 1, and at the same time, it is necessary to actually measure the interaction force between the operator and the master robot and the interaction force between the slave robot and the environment using a force sensor in a complex environment. SUMMARY

[0005] The main purpose of the present application is to provide a control method of a robot bilateral teleoperation system with time-varying time delay, so as to solve the technical problem that the bilateral teleoperation system in the prior art has poor system transparency and stability due to unknown external interaction force and time-varying time delay.

[0006] In order to achieve the above purpose, the present application provides a control method of a robot bilateral teleoperation system with time-varying time delay, and the technical scheme is as follows:

[0007] A control method for a robotic bilateral teleoperation system with time-varying time delay, comprising the following steps:

[0008] At the master robot side of the communication channel:

[0009] The communication channel acquires slave robot joint positions and outputs slave robot joint positions affected by time-varying time delay;

[0010] The master-side time delay state observer acquires the slave robot joint positions affected by time-varying time delay and processes to obtain an estimated value of the derivative of the slave robot joint positions affected by time-varying time delay, and then obtains an estimated value of the slave robot joint positions affected by time-varying time delay through an integrator;

[0011] The master-side force estimation algorithm processes the slave robot joint positions affected by time-varying time delay, the joint positions of the master robot, and the control torque of the master robot controller and outputs an estimated value of the master-side force;

[0012] The master robot controller acquires the estimated value of the slave robot joint positions affected by time-varying time delay, the estimated value of the master-side force, and the joint positions of the master robot and processes to obtain the control torque of the master robot controller;

[0013] The master robot acquires the master-side force and the control torque of the master robot controller and processes to obtain the joint positions of the master robot;

[0014] And / or, at the slave robot side of the communication channel:

[0015] The communication channel acquires master robot joint position transitions and outputs master robot joint positions affected by time-varying time delay;

[0016] The slave-side time delay state observer acquires the master robot joint positions affected by time-varying time delay and processes to obtain an estimated value of the derivative of the master robot joint positions affected by time-varying time delay, and then obtains an estimated value of the master robot joint positions affected by time-varying time delay through an integrator;

[0017] The slave-side force estimation algorithm processes the master robot joint positions affected by time-varying time delay, the joint positions of the slave robot, and the control torque of the slave robot controller and outputs an estimated value of the slave-side force;

[0018] The slave robot controller acquires the estimated value of the master robot joint positions affected by time-varying time delay, the estimated value of the slave-side force, and the joint positions of the slave robot and processes to obtain the control torque of the slave robot controller;

[0019] The slave robot acquires the slave-side force and the control torque of the slave robot controller and processes to obtain the joint positions of the slave robot.

[0020] On one hand, the control method of the present application can effectively estimate the interaction force of the system, instead of measuring the interaction force by the sensor, thereby avoiding the measurement noise and cost problems caused by the use of the force sensor. On the other hand, the control method of the present application does not require the constraint that the change rate of the time-varying time delay is less than 1 when ensuring the stability of the system. It can be seen that the control method of the present application can effectively solve the technical problems caused by the unknown external interaction force and the time-varying time delay in the master-slave robot, significantly improve the accuracy of the joint position and force tracking of the master-slave robot, and improve the transparency and stability of the bilateral teleoperation system. It has been verified that the control method of the present application can improve the transparency and stability of the bilateral teleoperation system to a certain extent when it is used on either the master robot side or the slave robot side of the communication channel. When the control method of the present application is used on both the master robot side and the slave robot side, the transparency and stability of the bilateral teleoperation system are the best.

[0021] The present application will be further described below in conjunction with the drawings and specific embodiments. Additional aspects and advantages of the present application will be partially given in the following description, partially become obvious from the following description, or be understood by the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which form a part of the present application, are used to help understand the present application and are incorporated in and constitute a part of the specification. The drawings provided in the accompanying drawings and the related description in the present application can be used to explain the present application, but do not constitute an improper limitation on the present application. In the drawings:

[0023] Figure 1 Structure schematic diagram of an embodiment of the control method of the bilateral teleoperation system of the robot with time-varying time delay of the present application. DETAILED DESCRIPTION

[0024] The present application will be further described below in conjunction with the drawings and specific embodiments. Additional aspects and advantages of the present application will be partially given in the following description, partially become obvious from the following description, or be understood by the practice of the present application.

[0025] The technical solutions and technical features provided in each part of the present application, including the following description, can be combined with each other without conflict.

[0026] In addition, the embodiments of the present application involved in the following description are generally only a part of the embodiments of the present application, not all the embodiments. Therefore, all other embodiments obtained by the ordinary skilled in the art based on the embodiments in the present application without making creative efforts should belong to the scope of protection of the present application.

[0027] With respect to the terms and units in the present invention. The terms "comprise", "have" and any variations thereof in the specification and claims of the present invention and related parts are intended to cover non-exclusive inclusion.

[0028] Figure 1 Structure diagram of an embodiment of the control method of the bilateral teleoperation system of the robot with time-varying time delay of the present invention.

[0029] As Figure 1 shown, the bilateral teleoperation system of the robot with time-varying time delay of the present invention is a nonlinear teleoperation system, wherein,

[0030] Master robot model:

[0031] Slave robot model:

[0032] wherein subscript m represents the master robot, subscript s represents the slave robot; q m is the joint position of the master robot, is the joint velocity of the master robot, is the joint acceleration of the master robot; q s is the joint position of the slave robot, is the joint velocity of the slave robot, is the joint acceleration of the slave robot; M m (q m ), M s (q s )∈R n×n are respectively the symmetric positive definite inertia matrices of the master robot and the slave robot; are respectively the centrifugal force and the Coriolis force of the master robot and the slave robot; G m (q m ), G s (q s )∈R n are respectively the gravity terms of the master robot teleoperation system and the slave robot teleoperation system; τ m , τ s ∈R n are respectively the control torques of the master robot controller and the slave robot controller; τ h , τ e ∈R n are respectively the master end force and the slave end force, the master end force being the interaction force between the operator and the master robot, and the slave end force being the interaction force between the slave robot and the environment; n represents the degree of freedom of the robot.

[0033] The above-mentioned embodiment of the control method of the bilateral teleoperation system is composed of the following steps:

[0034] (1) At the master robot side of the communication channel:

[0035] The communication channel obtains slave robot joint positions and outputs slave robot joint positions affected by time-varying time delay;

[0036] The master end time delay state observer obtains the slave robot joint positions affected by time-varying time delay and processes to obtain an estimated value of the derivative of the slave robot joint positions affected by time-varying time delay, and then obtains an estimated value of the slave robot joint positions affected by time-varying time delay through an integrator;

[0037] The master end force estimation algorithm processes the slave robot joint positions affected by time-varying time delay, joint positions of the master robot, and control torque of the master robot controller and outputs an estimated value of the master end force;

[0038] The master robot controller obtains the estimated value of the slave robot joint positions affected by time-varying time delay, the estimated value of the master end force, and the master robot joint positions and processes to obtain control torque of the master robot controller;

[0039] The master robot obtains the master end force and the control torque of the master robot controller and processes to obtain joint positions of the master robot;

[0040] (2) At the slave robot side of the communication channel:

[0041] The communication channel obtains master robot joint position changes and outputs master robot joint positions affected by time-varying time delay;

[0042] The slave end time delay state observer obtains the master robot joint positions affected by time-varying time delay and processes to obtain an estimated value of the derivative of the master robot joint positions affected by time-varying time delay, and then obtains an estimated value of the master robot joint positions affected by time-varying time delay through an integrator;

[0043] The slave end force estimation algorithm processes the master robot joint positions affected by time-varying time delay, joint positions of the slave robot, and control torque of the slave robot controller and outputs an estimated value of the slave end force;

[0044] The slave robot controller obtains the estimated value of the master robot joint positions affected by time-varying time delay, the estimated value of the slave end force, and the slave robot joint positions and processes to obtain control torque of the slave robot controller;

[0045] The slave robot obtains the slave end force and the control torque of the slave robot controller and processes to obtain joint positions of the slave robot.

[0046] Wherein, at the master robot side of the communication channel:

[0047] The master-side time-delay state observer is capable of estimating the slave robot position and velocity affected by time-varying time delay, and the expression is:

[0048]

[0049] The master-side force estimation algorithm is capable of estimating the master-side force, and the expression is:

[0050]

[0051] The master robot controller is:

[0052]

[0053] wherein, and are the estimations of the joint position and joint velocity of the slave robot affected by time-varying time delay respectively; χ s1 > 0 and χ s2 > 0 are constant gains of the master-side time-delay state observer; q s (t-d(t)) is the joint position of the slave robot affected by time-varying time delay; and are the derivatives of Z s1 (t) and Z s2 (t) respectively; is the estimation of the master-side force; δ is a constant; ω m is the bound of the master-side force, is the estimation of ω m , and b is a constant; α m is the auxiliary variable of the master robot; β m is the state variable of the master robot; is the derivative of the state variable; e m and are the joint position error and joint velocity error of the master robot respectively; M m -1 (q m ) is the inverse matrix of M m (q m ); P m and B m are positive definite matrices, which are the joint position gain and joint velocity gain of the master robot respectively; is the estimation of the joint position of the slave robot affected by time-varying time delay; is the estimation of the master-side force; t represents time, and d2(t) is the time-varying time delay of the slave-side communication channel.

[0054] The master robot controller can be regarded as consisting of 4 parts: the first part is Part 1 is about the joint position feedback law for the master robot to track the joint position of the slave robot Part 2 is about the joint velocity compensation Part 3 is about the master end force τ h compensation m Part 4 is about the model feedforward term of -G m (q m1 ) .

[0055] The estimated value of the joint position of the slave robot affected by the time-varying time delay in the master robot controller is updated by the master end time delay state observer is updated by the master end force estimation algorithm, which can significantly improve the accuracy of the joint position and force tracking of the master-slave robot.

[0056] On the slave robot side of the communication channel:

[0057] The slave end time delay state observer can estimate the master robot position and velocity affected by the time-varying time delay, expressed as:

[0058]

[0059] The slave end force estimation algorithm can estimate the slave end force, expressed as:

[0060]

[0061] The slave robot controller is:

[0062]

[0063] wherein, and are the estimates of the master robot joint position and joint velocity affected by the time-varying time delay; χ m1 > 0 and χ m2 > 0 are constant gains of the slave end time delay state observer; q m (t-d1(t)) is the master robot joint position affected by the time-varying time delay; and are the derivatives of Z m1 (t) and Z m2 (t), respectively; is the estimate of the slave end force; δ is a normal number; ω s is the bound of the slave end force, is the estimate of ω s , and b is a normal number; α s is the auxiliary variable of the slave robot; β sis the state variable of the slave robot, is the derivative of the state variable; e s and are the joint position error and joint velocity error of the slave robot, respectively; M s -1 (q m ) is the inverse matrix of M s (q m ); P s and B s are positive definite matrices, which are the joint position gain and joint velocity gain of the slave robot, respectively; is the estimated value of the master robot joint position affected by the time-varying time delay; is the estimated value of the slave end force; t represents time, and d1(t) is the time-varying time delay of the master end communication channel.

[0064] The slave robot controller can also be regarded as consisting of 4 parts: the first part is used as the joint position feedback law to realize the joint position tracking of the slave robot to the master robot; the second part is used to perform joint velocity compensation; the third part is used to compensate the slave end force τ e in the dynamics of the slave robot; and the fourth part is the model feedforward term with respect to G s (q s ).

[0065] The estimated value of the master robot joint position affected by the time-varying time delay in the slave robot controller is updated by the slave end time delay state observer, and the estimated value of the slave end force is updated by the slave end force estimation algorithm, so that the accuracy of the joint position and force tracking of the master-slave robot can be significantly improved.

[0066] The stability of the bilateral teleoperation system of the robot using the control method of the present application is verified by Lyapunov function as follows.

[0067] According to the above-mentioned design of the master robot controller and the slave robot controller, the Lyapunov function for the position and force tracking control research of the time-varying time delay bilateral teleoperation system based on the force estimation algorithm is selected as follows:

[0068]

[0069] Derivation is performed thereon:

[0070]

[0071] wherein q m (t) is the joint position of the master robot, q(t) is the joint velocity of the master robot s (t) is the joint position of the slave robot, q(t) is the joint velocity of the slave robot m (t), q(t) s (t) e R n D1, D2 are upper bounds of time-varying time delays d1(t), d2(t), B m -(D1+D2)I and B s -(D1+D2)I is a positive definite matrix, I is the identity matrix; Substituting the master-slave robot model and the master robot controller into the above equation, we have

[0072]

[0073] It can be shown that all the signals in V(t) are bounded, then we have q s (t) e L ∞ , Since we can get q m (t) - q s (t-d2(t)) e L ∞ , so the position tracking error between the master robot and the slave robot is bounded.

[0074] Since we have obtained where L ∞ represents a bounded function. According to the Barbalat lemma (J. J. E. Slotine, W. Li. Applied nonlinear control. Prentice-Hall, Englewood Cliffs, NJ, 1991), we have

[0075] According to the model of the bilateral teleoperation system, we have

[0076]

[0077] Therefore, is bounded.

[0078] From the obtained we can get

[0079] Substituting into the master robot model, the slave robot model, the master robot controller, and the slave robot controller, we have

[0080]

[0081] It can be seen that the control method of the application can effectively solve the influence of unknown external interaction force and time-varying time delay on system performance, so that the slave robot can accurately track the joint position of the master robot, and the operator can truly feel the interaction force between the environment and the slave robot.

[0082] The above describes the relevant content of the application. Those skilled in the art can implement the application based on the description. Based on the above content of the application, all other embodiments obtained by those skilled in the art without creative labor shall fall within the protection scope of the application.

Claims

1. A control method for a robot bilateral teleoperation system with time-varying time delay, characterized in that: Includes the following steps: On the main robot side of the communication channel: The communication channel acquires the robot joint position and outputs the robot joint position, which is affected by time-varying delay. The master delay state observer acquires the slave robot joint position affected by the time-varying delay and processes it to obtain an estimate of the derivative of the slave robot joint position affected by the time-varying delay. Then, it obtains the estimate of the slave robot joint position affected by the time-varying delay through an integrator. The master end force estimation algorithm processes the joint positions of the slave robot, the joint positions of the master robot, and the control torque of the master robot controller, which are affected by time-varying time delays, and outputs the estimated value of the master end force. The main robot controller acquires the estimated values ​​of the slave robot joint positions affected by time-varying time delay, the estimated values ​​of the master end force, and the main robot joint positions, and processes them to obtain the control torque of the main robot controller; The main robot acquires the main end force and the control torque of the main robot controller and processes them to obtain the joint position of the main robot; And / or, on the robot's side of the communication channel: The communication channel acquires the position changes of the main robot joints and outputs the main robot joint positions affected by time-varying delays. The system obtains the position of the main robot joint affected by the time-varying time delay from the end-delay state observer and processes it to obtain an estimate of the derivative of the main robot joint position affected by the time-varying time delay. Then, it obtains the estimate of the position of the main robot joint affected by the time-varying time delay through an integrator. The slave force estimation algorithm processes the master robot joint position, slave robot joint position, and slave robot controller control torque affected by time-varying time delay and outputs the estimated value of the slave force. The robot controller obtains the estimated values ​​of the master robot joint positions affected by time-varying time delay, the estimated values ​​of the slave end forces, and the slave robot joint positions, and processes them to obtain the control torque of the slave robot controller; The robot obtains the end force and the control torque of the robot controller and processes them to obtain the joint position of the robot.

2. The control method for a robot bilateral teleoperation system with time-varying delay as described in claim 1, characterized in that: A robot bilateral teleoperation system with time-varying delay is a nonlinear teleoperation system, in which... The main robot model is: From the robot model: Where the subscript m represents the master robot, and the subscript s represents the slave robot; q m The joint positions of the main robot, The joint speed of the main robot, The joint acceleration of the main robot; q s To determine the position of the robot's joints, To obtain the robot's joint speed, M is the acceleration from the robot's joints. m (q m ),M s (q s )∈R n×n These are the symmetric positive definite inertia matrices of the master robot and the slave robot, respectively. The centrifugal force and Coriolis force of the master robot and slave robot, respectively; G m (q m ),G s (q s )∈R n These are the gravity terms for the master robot teleoperation system and the slave robot teleoperation system, respectively; τ m ,τ s ∈R n These are the control torques of the master robot controller and the slave robot controller, respectively; τ h ,τ e ∈R n These are the master force and the slave force, respectively. The master force is the interaction force between the operator and the master robot, and the slave force is the interaction force between the slave robot and the environment; n represents the robot's degrees of freedom.

3. The control method for a robot bilateral teleoperation system with time-varying delay as described in claim 2, characterized in that: The master-end delay state observer is: in, and These are estimates of the joint positions and joint velocities of the robot after being affected by time-varying delays; χ s1 >0 and χ s2 >0 is the constant gain of the master-side delay state observer; q s (t-d2(t)) represents the position of the robot joint affected by time-varying time delay; and They are Z s1 (t) and Z s2 The derivative of d2(t); t represents time, and d2(t) is the time-varying delay of the slave communication channel.

4. The control method for a robot bilateral teleoperation system with time-varying delay as described in claim 2, characterized in that: The main end force estimation algorithm is as follows: in, The estimated value of the main end force; δ is a positive constant; ω m The boundary of the main force, It is ω m The estimated value, b is a positive constant; α m It is an auxiliary variable of the main robot; β m These are the state variables of the main robot; The derivative of the state variable; e m and These are the joint position error and joint velocity error of the main robot, respectively; M m -1 (q m ) is M m (q m The inverse matrix of ).

5. The control method for a robot bilateral teleoperation system with time-varying delay as described in claim 2, characterized in that: The main robot controller is: Among them, P m and B m These are positive definite matrices, and represent the joint position gain and joint velocity gain of the main robot, respectively. It is an estimate of the robot joint position after being affected by time-varying delay; The estimated value of the main end force.

6. The control method for a robot bilateral teleoperation system with time-varying delay as described in claim 2, characterized in that: The slave-end delay state observer is: in, and These are estimates of the joint positions and velocities of the main robot after being affected by time-varying delays; χ m1 >0 and χ m2 >0 is the constant gain of the slave-end delay state observer; q m (t-d1(t)) represents the position of the main robot joint affected by time-varying time delay; and They are Z m1 (t) and Z m2 The derivative of d1(t); t represents time, and d1(t) is the time-varying delay of the master-end communication channel.

7. The control method for a robot bilateral teleoperation system with time-varying delay as described in claim 2, characterized in that: The slave force estimation algorithm is as follows: in, Here is the estimated value of the end force; δ is a positive constant. ω s For the boundary of the end force, It is ω s The estimated value, b is a positive constant; α s It is an auxiliary variable from the robot; β s It comes from the robot's state variables. The derivative of the state variable; e s and These are the joint position error and joint velocity error of the robot, respectively; M s -1 (q m ) is M s (q m The inverse matrix of ).

8. The control method for a robot bilateral teleoperation system with time-varying delay as described in claim 2, characterized in that: The robot controller is: Among them, P s and B s These are positive definite matrices, representing the joint position gain and joint velocity gain of the robot, respectively; It is an estimate of the joint position of the main robot after being affected by time-varying delay; This is an estimate of the force at the end.

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