A non-zero-sum game-based auxiliary support control method for exo-limb robots

Abstract

The present invention discloses a non-zero-sum game-based auxiliary support control method for an exo-limb robot. The method comprises setting the parameters of the state transfer matrix and input matrix of the support control system according to the dynamics of the support control system, initializing basic parameters, and updating the state variables and state variable estimation deviations of the support control system; obtaining an estimate of the wearer's feedback gain according to the Lyapunov stability control theorem and a state observer; calculating the optimal feedback gain of the exo-limb according to the non-zero-sum control, game control, and the estimated value of the wearer's feedback gain; and achieving stable support of the exo-limb robot by adaptively adjusting the joint torque output of the exo-limb robot based on the dynamic formula of the exo-limb and the optimal feedback gain. The present invention can improve the stability and smooth interaction of the exo-limb robot during human-machine collaborative support tasks, effectively improving the success rate of overhead support operations and reducing the incidence of musculoskeletal injuries in users.

Description

Technical Field

[0001] The present invention relates to the technical field of exo-limb robots and human-machine coordinated control, and in particular to an auxiliary support control method for an exo-limb robot based on non-zero-sum game. Background Art

[0002] With the advancement of computer science, industrial production is becoming increasingly automated. However, due to limitations in process, cost, and space, many industrial production lines still require a significant number of manual tasks. However, the long-term overhead work performed by these workers can lead to low efficiency, muscle fatigue, decreased physical fitness, and even occupational musculoskeletal injuries. Therefore, to improve this situation, the use of exo-robots to assist with overhead tasks is an effective approach to mitigate occupational musculoskeletal injuries.

[0003] An exo-limb robot is a robot worn on a human body, capable of independently performing tasks using its additional arms. This is particularly true for overhead support tasks, where the exo-limb robot can replace the wearer's hands. However, because the exo-limb is worn on the wearer's body to perform overhead tasks, the rigid connection makes the exo-limb's support stability susceptible to the wearer's influence. Furthermore, because the output of the wearer and the exo-limb is difficult to coordinate, unintended forces can be applied to the wearer's shoulders, potentially leading to further injury. Summary of the Invention

[0004] The purpose of the present invention is to provide an external limb robot assisted support control method based on non-zero-sum game, which can effectively improve the stability of the external limb robot in assisting in performing overhead support tasks, and can improve the flexibility of the equipment by adaptively adjusting the feedback gain of the external limb robot, thereby reducing the reaction force on the wearer.

[0005] The present invention adopts the following technical solutions:

[0006] A non-zero-sum game-based auxiliary support control method for an external limb robot comprises the following steps:

[0007] S1. According to the dynamics of the supporting control system, set the parameters of the system's state transfer matrix A and input matrix B, and initialize the basic parameters, which include state variables and state variable estimation deviations.

[0008] S2. Update the state variables and state variable estimation deviations supporting the control system.

[0009] S3. According to Lyapunov's stability control theorem and the state observer, the estimated value of the wearer's feedback gain is obtained.

[0010] S4. Calculate the optimal feedback gain of the external limb based on the estimated values ​​of non-zero-sum control, game control, and wearer feedback gain.

[0011] S5. Based on the dynamic formula of the exo-limb and the optimal feedback gain, the joint torque output of the exo-limb robot is adaptively adjusted to achieve stable support of the exo-limb robot.

[0012] Furthermore, in step S1, the basic parameters also include the base height h of the external limb robot b , the height of the ceiling, the estimated values ​​of the system's state variables, and the mass m of the base of the external limb b , the mass of the support plate m p , mass of external limbs m s , the cost function parameter Q of the outer limb sl , the wearer's cost function parameter estimate Estimated value of wearer's feedback gain parameter The observation matrix parameter γ, the wearer feedback gain update parameter α and the lengths l1, l2, l3 of the link center of mass of the external limb to the joint.

[0013] Furthermore, in step S2, the update formula for the state variable and the state variable estimation deviation is:

[0014]

[0015]

[0016] Among them, h represents the height of the current support, Indicates the current speed of the support, h d Indicates the expected support height, represents the estimated value of the system's state variables, represents the estimated deviation of the updated state variable, and δ represents the updated state variable.

[0017] Furthermore, in step S3, updating the estimated value of the wearer feedback gain includes the following:

[0018] S301. The expression of the state observer supporting the control system is:

[0019]

[0020] in, represents the derivative of the estimated deviation of the state variable, P hl represents the wearer's feedback gain parameter, B T represents the transpose of B.

[0021] S302. The expression of Lyapunov function is:

[0022]

[0023] Where V represents the Lyapunov function, δ T represents the transpose of δ, express The transpose of , tr() represents the rank of the matrix, represents the deviation of the estimated value of the wearer's feedback gain, express The transpose of .

[0024] S303: Introducing the wearer's input gain parameter update rate The specific expression is:

[0025]

[0026] S304: Update the wearer input gain parameter. The specific calculation method is:

[0027]

[0028] in, represents the wearer input gain parameter at time t, represents the wearer input gain parameter at time t-1, and Δt represents the time interval.

[0029] S305: Calculate the estimated value of the wearer's feedback gain. The specific formula is:

[0030]

[0031] in, represents the estimated value of the wearer's feedback gain at time t.

[0032] Furthermore, in step S4, calculating the optimal feedback gain of the external limb includes the following:

[0033] When the wearer and the external limb coordinate to perform the overhead support task, the cost functions are:

[0034]

[0035]

[0036] in, represents the wearer's cost function, t0 represents the initial moment, represents the force exerted by the wearer on the movement of the support system, express The transpose of t represents the tth moment, J sl represents the cost function of the outer limb, u slrepresents the optimal output of the outer limb, Indicates u sl The transpose of .

[0037] The optimal control input of the exo-limb robot in the sense of Nash equilibrium is expressed as:

[0038] u sl =-Lδ

[0039] L=B T P sl

[0040] Where L represents the optimal feedback gain of the external limb; P sl Represents the feedback gain parameter of the robot.

[0041] P sl is the solution of the Riccati equation, and the specific expression is:

[0042]

[0043] Among them, A S represents the improved robot state transfer matrix, represents the estimated value of the wearer's feedback gain; Indicates A S The transpose of .

[0044] Furthermore, in step S5, the specific formula for adjusting the joint torque output of the external limb robot is:

[0045]

[0046] Where τ represents the joint torque output of the exo-limb robot; M() represents the stargazing matrix; θ represents the joint position of the exo-limb robot; represents the acceleration of the external limb robot joints; represents the joint velocity of the external limb robot; C() represents the vector containing the Coriolis and centripetal moments; g() represents the vector containing the gravitational moment; J represents the Jacobian matrix; J T represents the transpose of J; f represents the output force of the external limb robot, m p represents the mass of the support, and g represents the acceleration due to gravity.

[0047] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0048] 1. The method proposed in the present invention estimates the wearer's input through an observer based on the system state and the Lyapunov stability control method, which not only reduces the system's dependence on force sensors but also improves the stability of the control system.

[0049] 2. The method proposed in the present invention constructs the input force adjustment relationship between the wearer and the external limb robot through a non-cooperative game strategy, which can adjust the input force of the external limb robot according to the wearer's input feedback gain estimation, thereby improving the robot's coordination ability and flexibility.

[0050] 3. The method proposed in the present invention is applicable to the adaptive adjustment strategy of the auxiliary overhead support control task of the exo-limb robot. It can adjust the support position of the exo-limb robot according to the wearer's movements and improve the robot's stable support ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is an overall implementation flow chart of the present invention.

[0052] Figure 2 It is a scene graph of an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0054] To achieve the above objectives, the present invention proposes a non-zero-sum game-based auxiliary support control method for an external limb robot. Figure 1 The specific steps are as follows:

[0055] S1. According to the dynamics of the support control system, set the parameters of the state transfer matrix A and input matrix B of the system, and initialize the basic parameters, which include state variables, state variable estimation deviation, and the height h of the base of the external limb robot. b , the height of the ceiling, the estimated values ​​of the system's state variables, and the mass m of the base of the external limb b , the mass of the support plate m p , mass of external limbs m s , the cost function parameter Q of the outer limb sl , the wearer's cost function parameter estimate Estimated value of wearer's feedback gain parameter The observation matrix parameter γ, the wearer feedback gain update parameter α and the lengths l1, l2, l3 of the link center of mass of the external limb to the joint.

[0056] S2. Update the state variables and estimated deviations of the state variables supporting the control system. The specific formula is:

[0057]

[0058]

[0059] Among them, h represents the height of the current support, Indicates the current speed of the support, h d Indicates the expected support height, represents the estimated value of the system's state variables, represents the estimated deviation of the updated state variable, and δ represents the updated state variable.

[0060] S3. Based on Lyapunov's stability control theorem and the state observer, an estimated value of the wearer's feedback gain is obtained; the specific content is:

[0061] S301. The expression of the state observer supporting the control system is:

[0062]

[0063] in, represents the derivative of the estimated deviation of the state variable, P hl represents the wearer's feedback gain parameter, B T represents the transpose of B.

[0064] S302. The expression of Lyapunov function is:

[0065]

[0066] Where V represents the Lyapunov function, δ T represents the transpose of δ, surface

[0067] represents the transpose of δ, tr() represents the rank of the matrix, represents the deviation of the estimated value of the wearer's feedback gain, express The transpose of .

[0068] S303: In order to stabilize the system, the wearer input gain parameter update rate is introduced The specific expression is:

[0069]

[0070] S304: Update the wearer input gain parameter. The specific calculation method is:

[0071]

[0072] in, represents the wearer input gain parameter at time t, represents the wearer input gain parameter at time t-1, and Δt represents the time interval.

[0073] S305: Calculate the estimated value of the wearer's feedback gain. The specific formula is:

[0074]

[0075] in, represents the estimated value of the wearer's feedback gain at time t.

[0076] S4. Calculate the optimal feedback gain of the external limb based on the non-zero-sum control, game control, and the estimated value of the wearer's feedback gain; the specific content is:

[0077] When the wearer and the external limb coordinate to perform the overhead support task, the cost functions are:

[0078]

[0079]

[0080] in, represents the wearer's cost function, t0 represents the initial moment, represents the force exerted by the wearer on the movement of the support system, express The transpose of J sl represents the cost function of the outer limb, u sl represents the optimal output of the outer limb, Indicates u sl The transpose of .

[0081] The input of the cost function is optimal in the sense of Nash equilibrium, so the optimal control input of the exo-limb robot in the sense of Nash equilibrium is expressed as:

[0082] u sl =-Lδ

[0083] L=B T P sl

[0084] Where L represents the optimal feedback gain of the external limb; P sl Represents the feedback gain parameter of the robot.

[0085] P sl is the solution of the Riccati equation, and the specific expression is:

[0086]

[0087] Among them, A S represents the improved robot state transfer matrix, represents the estimated value of the wearer's feedback gain; Indicates AS The transpose of .

[0088] S5. Based on the exo-limb dynamics formula and optimal feedback gain, the exo-limb robot's joint torque output is adaptively adjusted to achieve stable support. The specific content is as follows:

[0089]

[0090] Where τ represents the joint torque output of the exo-limb robot; M() represents the stargazing matrix; θ represents the joint position of the exo-limb robot; represents the acceleration of the external limb robot joints; represents the joint velocity of the external limb robot; C() represents the vector containing the Coriolis and centripetal moments; g() represents the vector containing the gravitational moment; J represents the Jacobian matrix; J T represents the transpose of J; f represents the output force of the external limb robot, m p represents the mass of the support, and g represents the acceleration due to gravity.

[0091] Figure 2 (a) is a scene layout diagram of a specific implementation of the present invention, which includes a wearer, an external limb robot, an object to be supported (extruded board) and a ceiling. Figure 2 In (b), the wearer performs downward movement in the sagittal plane. At this time, the exo-limb robot performs auxiliary support control based on the detected human body movement position and speed through the proposed method. Figure 2 In (c), the wearer performs an upward movement in the sagittal plane, and the external limbs are also assisted in support control according to the proposed method. According to the example demonstration, the method proposed in the present invention can enable the external limb robot to provide stable support and reduce the reaction force on the wearer.

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A non-zero-sum game-based auxiliary support control method for an external limb robot, characterized in that: include: S1. According to the dynamics of the supporting control system, set the state transfer matrix of the system , input matrix Initialize the basic parameters, which include state variables and state variable estimation deviations; S2, updating the state variables and estimated deviations of the state variables supporting the control system; S3. According to Lyapunov's stability control theorem and the state observer, the estimated value of the wearer's feedback gain is obtained; specifically: S301. The expression of the state observer supporting the control system is: ； in, represents the derivative of the estimated deviation of the state variable, represents the wearer's feedback gain parameter, represents the observation matrix parameters, represents the estimated deviation of the updated state variable, represents the transpose of B, represents the wearer's feedback gain parameter estimate, Represents the updated state variables; S302. The expression of Lyapunov function is: ； Where V represents the Lyapunov function, express The transpose of express The transpose of represents the wearer feedback gain update parameter, tr() represents the rank of the matrix, represents the deviation of the estimated value of the wearer's feedback gain, express The transpose of S303: Introducing the wearer's input gain parameter update rate , the specific expression is: ； S304: Update the wearer input gain parameter. The specific calculation method is: ； in, represents the wearer input gain parameter at time t, represents the wearer input gain parameter at time t-1, Indicates a time interval; S305: Calculate the estimated value of the wearer's feedback gain. The specific formula is: ； in, represents the estimated value of the wearer's feedback gain at time t; S4. calculating the optimal feedback gain of the external limb based on the estimated values ​​of the non-zero-sum control, the game control, and the wearer's feedback gain; S5. Based on the dynamic formula of the exo-limb and the optimal feedback gain, the joint torque output of the exo-limb robot is adaptively adjusted to achieve stable support of the exo-limb robot.

2. The non-zero-sum game-based external limb robot auxiliary support control method according to claim 1 is characterized in that: In step S1, the basic parameters also include the base height of the external limb robot , the height of the ceiling, the estimated values ​​of the system's state variables, the mass of the exolimb base , the quality of the support plate , the quality of external limbs , the cost function parameters of the outer limb , the wearer's cost function parameter estimate , wearer's feedback gain parameter estimate , observation matrix parameters , wearer feedback gain update parameters and the length of the link center of mass of the outer limb to the joint 、 、 .

3. The non-zero-sum game-based external limb robot auxiliary support control method according to claim 1, characterized in that: In step S2, the update formula for the state variable and the state variable estimation deviation is: ； ； in, Indicates the height of the current support. Indicates the current speed of the support. Indicates the expected support height, represents the estimated value of the system's state variables, represents the estimated deviation of the updated state variable, Represents the updated state variable.

4. The non-zero-sum game-based auxiliary support control method for an external limb robot according to claim 1, characterized in that: In step S4, calculating the optimal feedback gain of the external limb includes the following: When the wearer and the external limb coordinate to perform the overhead support task, the cost functions are: ； ； in, represents the wearer’s cost function, represents the initial moment, represents the force exerted by the wearer on the movement of the support system, express The transpose of , t represents the tth moment, represents the estimated parameters of the wearer's cost function, represents the updated state variable, express The transpose of represents the cost function for the outer limb, denotes the cost function parameters of the outer limb, represents the optimal output of the outer limb, express The transpose of The optimal control input of the exo-limb robot in the sense of Nash equilibrium is expressed as: ； Where L represents the optimal feedback gain of the external limb; Represents the feedback gain parameter of the robot; represents the transpose of B; is the solution of the Riccati equation, and the specific expression is: ； in, represents the improved robot state transfer matrix, , represents the estimated value of the wearer's feedback gain; express The transpose of .

5. The non-zero-sum game-based auxiliary support control method for an external limb robot according to claim 1, characterized in that: In step S5, the specific formula for adjusting the joint torque output of the external limb robot is: ； in, represents the joint torque output of the exo-limb robot; represents the stargazing matrix; represents the joint positions of the external limb robot; represents the acceleration of the external limb robot joints; represents the joint velocity of the external limb robot; represents the vector containing the Coriolis and centripetal moments; represents the vector containing the gravitational moment; represents the Jacobian matrix; express The transpose of represents the output force of the exo-limb robot, , represents the optimal output of the outer limb, Indicates the mass of the support, Represents the acceleration due to gravity.

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