Physical man-machine interaction contact safety protection method and system based on Maxwell model

Abstract

The invention discloses a physical man-machine interaction contact safety protection method and system based on a Maxwell model, and the method comprises the steps: building a human body physical model, and expressing the effective mass, elastic coefficient and maximum allowable impact force physical attributes of each part of a human body; kinematics, statics and dynamics models of the robot are established, and the relation between the joint space displacement, speed, torque and mass of the robot and the tail end speed, tail end rigidity and effective mass is expressed; a physical man-machine interaction model is established, and the relation between the joint displacement, speed and mass of the robot and the physical man-machine interaction impact force is expressed; physical man-machine interaction contact characteristics are calculated, and impact duration, the maximum impact force, a contact damping coefficient and a recovery coefficient are calculated; and 5, robot safety protection measures are formulated, and the safety of physical man-machine interaction is guaranteed. According to the method, the solution of a Hertz contact stiffness parameter is avoided, the safety of physical man-machine interaction can be evaluated through the impact duration and the maximum impact force, and a theoretical basis is provided for the design of a robot man-machine interaction system.

Description

Technical Field

[0001] The present invention relates to the field of robotics technology, and in particular to a physical human-machine interaction contact safety protection method and system based on a Maxwell model. Background Art

[0002] With the development of industries such as 3C, electric power, shipbuilding, and aerospace, flexible manufacturing cells with human-in-the-loop (HIL) have become an effective solution for high-variety, low-batch discrete manufacturing. The prerequisite for a HIL-integrated sensing-perception-control motion control strategy is the operator's safety within the HIL, specifically the safety performance of physical human-robot interaction. Furthermore, the physical contact characteristics of HIL (impact duration, maximum impact force, etc.) serve as control inputs for the motion control strategy. Therefore, the safety performance of industrial robots, especially the safety of HIL, is a key consideration in the design of HIL systems. Currently, robot safety performance evaluation metrics primarily focus on energy, distance, pressure, and force. Contact impact force is an input to compliant control algorithms. These numerical solutions typically model the robot and operator as rigid points, ignoring the operator and robot's posture, stiffness, and damping characteristics. Furthermore, they can only calculate the robot's safety performance or contact characteristics at specific postures and velocities. ISO / TS15066 discloses a simple physical human-machine interaction modeling method, but does not consider the damping and stiffness characteristics of robots and operators. Various physical human-machine interaction models based on the Hunt-Crossley model have been disclosed, but the Hertz contact stiffness parameter differs from the spring stiffness in Hooke's law. This stiffness is independent of the contact deformation and completely depends on the geometry and material properties of the contacting bodies. Humans and robots are typical nonlinear dynamic systems, making the Hertz contact stiffness difficult to confirm. Physical human-machine interaction models based on the Hunt-Crossley model struggle to accurately describe human-machine interaction contact characteristics, such as impact force and impact duration. Furthermore, how to classify robots into safety levels using physical human-machine interaction models and implement different protective measures based on safety levels has not been fully explored. Summary of the Invention

[0003] In response to the above problems, the present invention provides a physical human-computer interaction contact safety protection method and system based on the Maxwell model. By solving the vibration equation of physical human-computer interaction, the solution of Hertz contact stiffness parameters is avoided. The physical human-computer interaction model can express the relationship between the stiffness, damping, mass and impact force and impact time of the interactive system. The safety of physical human-computer interaction can be evaluated by the impact duration, maximum impact force and recovery coefficient, providing reference and basis for the design of human-computer interaction system of flexible manufacturing unit.

[0004] The technical solutions to achieve this purpose are:

[0005] In a first aspect, the present invention provides a physical human-machine interaction contact safety protection method based on the Maxwell model, comprising the following steps:

[0006] Step 1: Establish a human body physical model to describe the physical properties of each part of the human body, including effective mass, elastic coefficient, and maximum allowable impact force;

[0007] Step 2: Establish the robot's kinematic, static, and dynamic models to describe the relationship between the robot's joint spatial displacement, velocity, torque, mass, and the terminal velocity, terminal stiffness, and effective mass;

[0008] Step 3: Based on the human body physical model and the robot kinematic, static, and dynamic models, a physical human-machine interaction model based on the Maxwell model is established to describe the relationship between the robot's joint displacement, velocity, mass, and the physical human-machine interaction impact force.

[0009] Step 4: Based on the physical human-computer interaction model, calculate the physical human-computer interaction contact characteristics, including impact duration, maximum impact force, contact damping coefficient, and recovery coefficient;

[0010] Step 5: Based on the contact characteristics of physical human-machine interaction, clarify the safety factor of physical human-machine interaction, formulate robot safety protection measures, and ensure the safety of physical human-machine interaction.

[0011] Furthermore, the physical properties are determined through human body mechanics tests and prosthetic impact tests, and the human body parts include the head, neck, back and shoulders, chest, abdomen, upper arms, lower arms, hands, thighs and knees, and calves.

[0012] Furthermore, the physical human-computer interaction model based on the Maxwell model is:

[0013]

[0014] Among them, F c Indicates the physical human-computer interaction impact, k c is the contact stiffness; δ(t) is the relative contact deformation; λ c is the contact damping coefficient; is the relative collision velocity.

[0015] Furthermore, the impact duration is:

[0016]

[0017] Among them, m c represents the effective mass after the collision.

[0018] Furthermore, the maximum impact force is:

[0019] F c_max =Max.(F c ).

[0020] Furthermore, the contact damping coefficient is:

[0021]

[0022] Among them, C R is the coefficient of restitution.

[0023] Furthermore, the restitution coefficient is solved by a numerical method or an optimization method.

[0024] Furthermore, the coefficient of restitution is solved by numerical methods, specifically including:

[0025] Step 8-1: Set the equidistant recovery coefficient C R The value interval (0,1), discrete point value;

[0026] Step 8-2: Calculate the contact damping coefficient λ at discrete points of the restitution coefficient c , impact duration t max ;

[0027] Step 8-3: Set the duration of the equidistant scattered impact t max The value range and discrete point values ​​of the impact duration are calculated, and the physical human-computer interaction impact force F is calculated under the discrete points of the impact duration. c ;

[0028] Step 8-4: Draw the impact time-impact force curve and calculate the maximum impact force F at the discrete points of the recovery coefficient. c_max ;

[0029] Step 8-5, calculate t max / 2 impact time, physical human-computer interaction impact force F c (t max / 2);

[0030] Step 8-6: Calculate the physical human-computer interaction impact force F c (t max / 2) and F c_max The error rate between

[0031] Step 8-7: Select the recovery coefficient C with the smallest error rate value R is the ideal restitution coefficient value.

[0032] Furthermore, the safety factor of physical human-computer interaction is:

[0033]

[0034] Among them, F c_max is the maximum impact force at the discrete point of the restitution coefficient, F H is the maximum permissible impact force on the human body part;

[0035] When N≤1, physical human-computer interaction is inherently safe and does not require safety protection; when 1<N≤2, physical human-computer interaction is risky and protective equipment needs to be worn; when N>2, physical human-computer interaction is extremely risky and physical isolation between humans and computers is required.

[0036] In a second aspect, the present invention provides a physical human-machine interaction contact safety protection system based on the Maxwell model, comprising:

[0037] The human body physical model establishment unit is used to establish a human body physical model and describe the physical properties of each part of the human body, such as effective mass, elastic coefficient, and maximum allowable impact force;

[0038] The robot kinematics, statics and dynamics model building unit is used to build the robot kinematics, statics and dynamics models, and describe the relationship between the robot joint spatial displacement, velocity, torque, mass and the terminal velocity, terminal stiffness and effective mass;

[0039] The physical human-machine interaction model building unit is used to build a physical human-machine interaction model based on the Maxwell model to describe the relationship between the robot's joint displacement, speed, mass and the physical human-machine interaction impact force;

[0040] The physical human-computer interaction contact characteristics calculation unit is based on the physical human-computer interaction model and is used to calculate the physical human-computer interaction contact characteristics, including impact duration, maximum impact force, contact damping coefficient, and recovery coefficient;

[0041] The robot safety protection measures determination unit, based on the physical human-machine interaction contact characteristics, clarifies the physical human-machine interaction safety factor, formulates robot safety protection measures, and ensures the safety of physical human-machine interaction.

[0042] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0043] (1) The physical human-machine interaction model provided by the present invention not only takes into account the robot's posture, speed, mass, stiffness and other characteristics, but also takes into account the operator's contact parts, the mass and stiffness of the contact parts and other characteristics;

[0044] (2) The physical human-machine interaction model provided by the present invention avoids the solution of Hertz contact stiffness parameters and accurately describes the human-machine interaction contact characteristics, such as impact force and impact duration. The impact duration and maximum impact force can be used to evaluate the safety of physical human-machine interaction, providing a theoretical basis for the design of robot human-machine interaction systems.

[0045] (3) The physical human-machine interaction contact characteristics provided by the present invention can provide designers with safety system design index requirements, reducing or eliminating risks from the design source. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0047] Figure 1 1 is a flow chart of a physical human-machine interaction contact safety protection method based on the Maxwell model provided in Example 1 of the present invention;

[0048] Figure 2 The human body physical model provided in Example 1 of the present invention;

[0049] Figure 3 A schematic diagram of a physical human-computer interaction model provided in Example 1 of the present invention;

[0050] Figure 4 A schematic diagram of safety protection measures corresponding to the physical human-computer interaction safety factor provided in Example 1 of the present invention;

[0051] Figure 5 A schematic flow chart of a method for calculating the coefficient of restitution provided in Example 2 of the present invention;

[0052] Figure 6 This is a schematic diagram of the impact time-impact force curve provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0053] To facilitate understanding of the present invention, a more comprehensive description of a flow chart of a physical human-machine interaction contact safety protection method based on the Maxwell model will be given below with reference to the relevant accompanying drawings. The accompanying drawings provide a preferred embodiment of a physical human-machine interaction contact safety protection method based on the Maxwell model. However, a physical human-machine interaction contact safety protection method based on the Maxwell model can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of a physical human-machine interaction contact safety protection method based on the Maxwell model more thorough and comprehensive.

[0054] Example 1

[0055] Figure 1 The figure is a flow chart of a physical human-machine interaction contact safety protection method based on the Maxwell model of the present invention. By way of example, the physical human-machine interaction contact characteristics calculation is performed according to the present invention, and the steps are as follows:

[0056] A: Building a physical model of the human body

[0057] Figure 2 A human body model part diagram is provided, wherein the human body physical model expresses the effective mass m of each part of the human body. H , elastic coefficient k H , Maximum allowable impact force F H Physical properties: The human body parts are the head, neck, back and shoulders, chest, abdomen, upper arms, lower arms, hands, thighs and knees, and calves. The physical properties of the human body parts are determined through human body mechanics tests and prosthetic impact tests.

[0058] B: Establish the robot's kinematic, static, and dynamic models to describe the relationship between the robot's joint spatial displacement, velocity, torque, mass, and end-point velocity, end-point stiffness, and effective mass;

[0059] The robot kinematic model can describe the mapping between the robot joint velocity and the Cartesian space velocity, and its mathematical expression is:

[0060]

[0061] Where V represents the terminal velocity vector of the robot, Θ represents the joint displacement vector, and J(Θ) represents the Jacobian matrix. Represents the joint velocity vector.

[0062] The robot statics model can describe the mapping between the robot joint stiffness and the Cartesian space stiffness, and its mathematical expression is:

[0063] K(Θ)=J(Θ) -T kJ(Θ)-1

[0064] Where K represents the robot end stiffness matrix, k represents the robot joint stiffness matrix;

[0065] The robot dynamics model can describe the mapping of joint torque, mass, damping and robot effective mass and Cartesian space force, and its mathematical expression is:

[0066]

[0067] Where M(Θ) is the robot mass matrix, are the centrifugal force and Coriolis force vectors, G(Θ) is the gravity vector, τ represents the joint torque vector, τ c represents the external contact torque vector;

[0068] C: Establish a physical human-computer interaction model

[0069] The physical human-machine interaction model describes the relationship between the robot's joint displacement, velocity, mass and the physical human-machine interaction impact force; Figure 3 A schematic diagram of the physical human-computer interaction model is provided.

[0070] The mathematical expression of the physical human-computer interaction model based on the Maxwell model is:

[0071]

[0072] The modeling process is as follows:

[0073] The mathematical expression of the vibration equation corresponding to the physical human-computer interaction linear collision behavior is:

[0074]

[0075] in is the relative collision acceleration; is the relative collision velocity; δ(t) is the relative contact deformation; λ c is the contact damping coefficient;

[0076] m c It represents the effective mass after the collision, and its calculation process is:

[0077]

[0078] m R Represents the effective mass of the robot in direction u, and its calculation process is

[0079]

[0080] k c is the contact stiffness, and its calculation process is:

[0081]

[0082] k R is the end stiffness of the robot in direction u, and its calculation process is:

[0083]

[0084] The mathematical expression of the solution of the vibration equation is:

[0085]

[0086] in Represents the relative initial collision velocity. Assuming that the operator's movement speed is much smaller than the robot's movement speed, Represents the vibration frequency; ξ=λ c / (2m c ω) represents the damping of the vibration system, represents the natural frequency;

[0087] The mathematical expression of the physical human-computer interaction model is:

[0088]

[0089] D: Calculate physical human-computer interaction contact characteristics, including impact duration, maximum impact force, contact damping coefficient, and recovery coefficient.

[0090] The mathematical expression of the impact duration is:

[0091]

[0092] The mathematical expression of the maximum impact force is:

[0093] F c_max =Max.(F c )

[0094] The mathematical expression of the contact damping coefficient is:

[0095]

[0096] The restitution coefficient C R The solution is solved by numerical method or optimization method;

[0097] E: Develop robot safety protection measures

[0098] The safety protection measures can ensure the safety of physical human-computer interaction; the safety factor of physical human-computer interaction is clarified, and its mathematical expression is:

[0099]

[0100] like Figure 4 As shown, when N≤1, physical human-computer interaction is inherently safe and no safety protection is required; when 1<N≤2, physical human-computer interaction is risky and protective equipment needs to be worn; when N>2, physical human-computer interaction is extremely risky and physical isolation of humans and computers is required.

[0101] The wearable protective device provided by the present invention mainly includes a safety helmet, goggles, labor protection gloves, labor protection work clothes, etc. The human-machine physical isolation method provided by the present invention is a safety grating, a protective fence, a distance sensor, etc.

[0102] The present invention provides a physical human-machine interactive contact safety protection system based on the Maxwell model, comprising:

[0103] The human body physical model establishment unit is used to establish a human body physical model and describe the physical properties of each part of the human body, such as effective mass, elastic coefficient, and maximum allowable impact force;

[0104] The robot kinematics, statics and dynamics model building unit is used to build the robot kinematics, statics and dynamics models, and describe the relationship between the robot joint spatial displacement, velocity, torque, mass and the terminal velocity, terminal stiffness and effective mass;

[0105] The physical human-machine interaction model building unit is used to build a physical human-machine interaction model based on the Maxwell model to describe the relationship between the robot's joint displacement, speed, mass and the physical human-machine interaction impact force;

[0106] The physical human-computer interaction contact characteristics calculation unit is based on the physical human-computer interaction model and is used to calculate the physical human-computer interaction contact characteristics, including impact duration, maximum impact force, contact damping coefficient, and recovery coefficient;

[0107] The robot safety protection measures determination unit, based on the physical human-machine interaction contact characteristics, clarifies the physical human-machine interaction safety factor, formulates robot safety protection measures, and ensures the safety of physical human-machine interaction.

[0108] Example 2

[0109] like Figure 5 FIG. 1 is a flow chart of a method for calculating the coefficient of restitution according to the present invention. For example, the steps for calculating the physical human-machine interaction contact characteristics according to the present invention are as follows:

[0110] D1: Set the equidistant recovery coefficient C R The value interval of is (0,1), and the discrete point value is 9;

[0111] D2: Calculate the contact damping coefficient λ at discrete points of the restitution coefficient c , impact duration t max ;

[0112] D3: Set the duration of equidistant scattered impact t max The value range of the discrete point is 99, and the physical human-computer interaction impact force F under the discrete point of the impact duration is calculated c ;

[0113] D4: Draw Figure 6 The impact time-impact force curve is shown, and the maximum impact force F at the discrete point of the recovery coefficient is solved. c_max ;

[0114] D5: Calculate t max / 2 impact time, physical human-computer interaction impact force F c (t max / 2);

[0115] D6: Calculate the physical human-computer interaction impact force F c (t max / 2) and F c_max The error rate between

[0116] D7: Select the recovery coefficient C with the smallest error rate E value R is the ideal restitution coefficient value.

[0117] Matters not covered by this invention are known in the art. The above embodiments are intended only to illustrate the technical concepts and features of this invention. Their purpose is to enable those skilled in the art to understand the contents of this invention and implement them accordingly. They are not intended to limit the scope of protection of this invention. Any equivalent changes or modifications made in accordance with the spirit and essence of this invention are intended to be covered by the scope of protection of this invention.

Claims

1. A physical human-computer interaction contact safety protection method based on the Maxwell model, characterized in that: including: Step 1: Establish a human body physical model to describe the physical properties of the effective mass, elastic coefficient, and maximum allowable impact force of each part of the human body; Step 2: Establish a robot kinematics, statics, and dynamics model to describe the relationships between the joint space displacement, velocity, torque, mass of the robot and the end velocity, end stiffness, and effective mass; Step 3: Based on the human body physical model and the robot kinematics, statics, and dynamics models, establish a physical human-machine interaction model based on the Maxwell model to describe the relationships between the robot joint displacement, velocity, mass, and the physical human-machine interaction impact force; Step 4: Based on the physical human-machine interaction model, calculate the physical human-machine interaction contact characteristics, including impact duration, maximum impact force, contact damping coefficient, and restitution coefficient; Step 5: Based on the physical human-machine interaction contact characteristics, clarify the physical human-machine interaction safety factor, formulate robot safety protection measures, and ensure the safety of physical human-machine interaction.

2. A physical human-machine interaction contact safety protection method based on the Maxwell model according to claim 1, characterized in that: The physical properties are determined through human mechanics tests and prosthetic impact tests. The human body parts include the head, neck, back and shoulders, chest, abdomen, upper arm, lower arm, hand, thigh and knee, and calf.

3. The physical human-machine interaction contact safety protection method based on the Maxwell model according to claim 1 is characterized in that: The physical human-machine interaction model based on the Maxwell model is: Among them, F c Indicates the physical human-computer interaction impact, k c is the contact stiffness; δ(t) is the relative contact deformation; λ c is the contact damping coefficient; is the relative collision velocity.

4. A physical human-machine interaction contact safety protection method based on the Maxwell model according to claim 3, characterized in that: The impact duration is: Among them, m c represents the effective mass after the collision.

5. A physical human-machine interaction contact safety protection method based on the Maxwell model according to claim 4, characterized in that: The maximum impact force is: F c_max =Max.(F c )。 6. A physical human-machine interaction contact safety protection method based on the Maxwell model according to claim 5, characterized in that: The contact damping coefficient is: Among them, C R is the coefficient of restitution.

7. The physical human-machine interaction contact safety protection method based on the Maxwell model according to claim 1 is characterized in that: The restitution coefficient is solved by numerical methods or optimization methods.

8. The physical human-machine interaction contact safety protection method based on the Maxwell model according to claim 7 is characterized in that: The specific process of solving the restitution coefficient by numerical methods includes: Step 8-1: Set the equidistant recovery coefficient C R The value interval (0,1), discrete point value; Step 8-2: Calculate the contact damping coefficient λ at the discrete points of the restitution coefficient c , impact duration t max ; Step 8-3: Set the duration of the equidistant scattered impact t max The value range and discrete point values ​​of the impact duration are calculated, and the physical human-computer interaction impact force F is calculated under the discrete points of the impact duration. c ; Step 8-4: Draw the impact time-impact force curve and calculate the maximum impact force F at the discrete points of the recovery coefficient. c_max ; Step 8-5, calculate t max / 2 impact time, physical human-computer interaction impact force F c (t max / 2); Step 8-6: Calculate the physical human-computer interaction impact force F c (t max / 2) and F c_max The error rate between Step 8-7: Select the recovery coefficient C with the smallest error rate value R is the ideal restitution coefficient value.

9. The physical human-machine interaction contact safety protection method based on the Maxwell model according to claim 7, characterized in that: The physical human-machine interaction safety factor is: Among them, F c_max is the maximum impact force at the discrete point of the restitution coefficient, F H is the maximum permissible impact force on a part of the human body; When N ≤ 1, the physical human-machine interaction is intrinsically safe and no safety protection is required; when 1 < N ≤ 2, there are risks in the physical human-machine interaction and protective devices need to be worn; when N > 2, the risks of physical human-machine interaction are extremely high and physical isolation between humans and machines is required.

10. A physical human-machine interactive contact safety protection system for implementing the method according to any one of claims 1 to 9, characterized in that: including: A human body physical model establishment unit for establishing a human body physical model to describe the physical properties of the effective mass, elastic coefficient, and maximum allowable impact force of each part of the human body; A robot kinematics, statics, and dynamics model establishment unit for establishing a robot kinematics, statics, and dynamics model to describe the relationships between the joint space displacement, velocity, torque, mass of the robot and the end velocity, end stiffness, and effective mass; A physical human-machine interaction model establishment unit for establishing a physical human-machine interaction model based on the Maxwell model to describe the relationships between the robot joint displacement, velocity, mass, and the physical human-machine interaction impact force; A physical human-machine interaction contact characteristics calculation unit for calculating the physical human-machine interaction contact characteristics, including impact duration, maximum impact force, contact damping coefficient, and restitution coefficient, based on the physical human-machine interaction model; A robot safety protection measure determination unit for clarifying the physical human-machine interaction safety factor and formulating robot safety protection measures based on the physical human-machine interaction contact characteristics to ensure the safety of physical human-machine interaction.

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