Topology design method for macro-micro synergy of thin-walled structures and robot lower leg structural members

Abstract

The present invention provides a topology design method for macro-micro synergy of thin-walled structures. [Solution] The method includes the steps of (1) setting the operating conditions 1 and 2, (2) combining the operating conditions 1 and 2 to design an initial lower leg model and performing finite element calculation, (3) reconstructing a lightweight lower leg model by a topology design method, (4) maintaining the thickness of the outer case of the reconstructed lightweight lower leg model at 2 mm and replacing the core part with a dot matrix structure, (5) designing a variable thickness for the case based on the finite element calculation result, (6) designing the change in the side length of the unit cell or the diameter of the rod for the dot matrix structure of the core part, and (7) dynamically repeating the result of the topology design to obtain a uniform stress field. The present invention further provides a robot lower leg model by a topology design method of macro-micro synergy of a thin-walled structure. The macro-micro synergy topology design of the present invention realizes the integration of structural members and high aesthetics, reduces the weight by 30% in total, and satisfies the strength and rigidity requirements for the use of robots.

Description

[Technical Field]

[0001] The present invention relates to the field of structural design of intelligent robots, and in particular to a topology design method for macro-micro synergy of thin-walled structures and a robot lower leg model. [Background technology]

[0002] Humanoid robots are robots developed from bionic ideas, with similar height, weight, and joint flexibility to humans. Because humans have evolved over a long period of time to form their current body structure and joint flexibility characteristics, humanoid robots have clear advantages over other types of robots in terms of movement stability and flexibility. Currently, humanoid robots can perform highly challenging movements such as running, dancing, and parkour, and can run at normal human speeds in outdoor environments such as grass and snow. They are beginning to prove their value in transportation, firefighting, and other areas. In the future, with further improvements in the performance of drive joints, force and position sensors, and control algorithms, humanoid robots may become indispensable assistant robots in living rooms.

[0003] The design principles for structural components of humanoid robots are light weight, high strength, low rotational inertia, and high aesthetics. Lighter mass can reduce the energy consumption of the robot and extend its operational time, which is significant for the future birth of humanoid robots. Higher strength can meet the kinematic requirements of the robot in each operating situation. Low rotational inertia allows the robot to complete high-speed switching of movements when moving. High aesthetics can improve the user's quality experience of the robot. Furthermore, when aesthetics reach a level that can be used as exterior components, they can replace the exterior components of the robot, thereby further reducing the overall mass of the robot.

[0004] Currently, there are not many units researching humanoid robots in China, and most structural components are still designed as traditional machined sheet or bar bodies with mechanical connections using screw threads, which involves many screws, poor aesthetics, and the screw connections are prone to breakdown during movement. Summary of the Invention [Problem to be solved by the invention]

[0005] To overcome the above problems, the present invention provides a topology design method for macro-micro synergy of thin-walled structures and a robotic lower limb model. [Means for solving the problem]

[0006] In a first aspect of the present invention, there is provided a method for topology design of macro-micro synergies for thin-walled structures, comprising: Based on the robot's motion process, two gaits are extracted as two types of motion situations. Motion situation 1 is the gait when the robot stands on one foot and the other foot touches the ground, and motion situation 2 is the gait when the robot stands up from a low position to a high position (Step (1)). Step (2) of combining the motion situation 1 and the motion situation 2 to design an initial lower leg model and perform finite element calculation; Step (3) of reconstructing a lightweight lower leg model by a topology design method based on the principles of maximum stiffness and minimum material; For the reconstructed lightweight lower leg model, the basic thickness of the outer case is maintained at 2 mm, the core part is made watermarked, and the core part is replaced with a dot matrix structure (step (4)); Step (5) designing a variable thickness for the case based on the finite element calculation results, i.e., setting a variable thickness area near the inner surface of the case, and increasing the variable thickness when the equivalent stress at that location is large, and decreasing the variable thickness when the equivalent stress is small; (6) designing the change in the side length of the unit cell or the diameter of the rods for the dot matrix structure of the core part, and setting the change in the side length of the unit cell or the diameter of the rods based on a function related to the spatial position of the side length of the unit cell or the diameter of the rods by setting parameters in a software GUI language or by editing code in programming software; and (7) dynamically iterating the topology design results to obtain a nearly uniform stress field.

[0007] Furthermore, in step (2), the input of the combined load is three times or more of the user's own weight when standing and the peak value of the torque at the knee position when standing up.

[0008] Furthermore, the reconstructed lightweight model in step (3) is a continuum, and the reconstructed lightweight lower leg model reflects the material distribution characteristics obtained by finite element simulation of the structural member.

[0009] Furthermore, in step (4), the thickness of the outer case is 2 mm, and the core portion is a dot matrix with uniform density.

[0010] Furthermore, the thin wall thickness and the dot matrix density of the core portion are mapped based on the results of stress field simulation.

[0011] Furthermore, after the first mapping is completed, the stress field of the new model is calculated and then the model parameters are iteratively optimized until the difference between the maximum stress and the minimum stress in the stress field is smaller than 50 MPa.

[0012] A second aspect of the present invention provides a robot shank model manufactured by a topology design method for thin-walled macro-micro synergy, comprising four topological shank tubes, a plurality of first short columns of the shank and second long columns of the shank connected between two adjacent topological shank tubes, the bottoms of the four topological shank tubes connected at a single point, bearing mounting surfaces connected to the tips of two of the four topological shank tubes, motor mounting plates connected to the tips of the remaining two topological shank tubes, wiring holes for the shank provided on the bearing mounting surfaces, a surface case for the shank provided on the surface of the topological shank tubes, a partial thickening area for the case connection holes provided on the surface case of the topological shank, and a core dot matrix or a variable density dot matrix provided in the core part of the topological shank tube.

[0013] The operating principle of the present invention is that the ultimate goal of lightweighting a structural component is to achieve a "uniform stress field," i.e., the difference between the maximum and minimum stresses in the structural component's stress field during application and operation is within a narrow range, resulting in a uniform stress field. To achieve this goal, a macro-micro synergistic design is required. By using a macro topology design, material can be reduced in areas with low stress and reserved in areas with high stress. Based on the macro layout, areas with relatively low internal stress can be designed as a dot matrix, and the density of the dot matrix can be adjusted according to the magnitude of the stress. This macro-micro synergistic design allows the structural component to maintain precision at the connection positions of the structural components while significantly reducing the weight of the structure. [Effects of the Invention]

[0014] The beneficial effects of this invention are that macro-topology design achieves integration and weight reduction of robot structural components. In this case, the topology design of the lower leg achieves a macro-topology structure that is 10% lighter than conventional machined structural components. By adding a micro-topology based on the macro-topology design, the core entity of the macro-topology structure is replaced by a dot matrix in the internal space, and by adjusting the partial thickness according to the stress field, the structural weight is reduced by an additional 20% compared to conventional machined components. The macro-micro synergistic topology design achieves structural integration and high aesthetic quality, while reducing the total weight by 30%. At the same time, the strength and rigidity meet the requirements for robot use. [Brief explanation of the drawings]

[0015] [Figure 1] Figure 1 shows the initial model of the topological lower leg. [Figure 2] Figure 2 is a structural diagram showing the topology shank. [Figure 3] Figure 3 is a structural diagram showing the topological lower leg watermark case. [Figure 4] FIG. 4 is a schematic diagram showing a variable thickness case. [Figure 5] FIG. 5 is a schematic diagram showing the dot matrix of the core part of the topology crus. [Figure 6] FIG. 6 is a partial enlarged view of a portion A in FIG. [Figure 7] FIG. 7 is a schematic diagram showing a variable density dot matrix. DETAILED DESCRIPTION OF THE INVENTION

[0016] The technical solution of the present invention patent will be clearly and completely described below with reference to the drawings, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Any other embodiments that a person skilled in the art can obtain based on the embodiments of the present invention without any inventive efforts fall within the protection scope of the present invention.

[0017] In describing the present invention, it should be explained that the orientations or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are orientations or positional relationships shown in the drawings, and are intended merely to facilitate and simplify the description of the present invention, and do not indicate or imply that the indicated devices or elements must necessarily have a particular orientation or be constructed or operated in a particular orientation, and therefore should not be understood as limiting the present invention. Furthermore, the terms "first," "second," and "third" are intended merely for the purpose of explanation, and should not be understood as indicating or implying relative importance.

[0018] In describing the present invention, unless otherwise clearly specified and limited, the terms "attached," "coupled," and "connected" should be understood in a broad sense, and may refer to, for example, a fixed connection, a detachable connection, or an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate element, or internal communication between two elements. Those skilled in the art can understand the specific meanings of the above terms in the present invention according to specific circumstances.

[0019] Example 1 Referring to the drawings, the topology design method for macro-micro synergy of thin-walled structures includes the following steps: In step (1), two gaits are extracted as two types of motion situations based on the robot's motion process. Motion situation 1 is a gait in which the robot stands on one foot and the other foot touches the ground. Motion situation 2 is a gait in which the robot stands up from a low position to a high position. In step (2), operation situation 1 and operation situation 2 are combined, and the combined load input is more than three times the robot's own weight when standing and the peak torque value at the knee position when standing up. The initial lower leg model shown in Figure 1 is designed and finite element calculations are performed, and the initial model can reflect the connection positions and positional accuracy between the lower leg, upper leg, foot, etc. The initial configuration of the lower leg is constructed, and this initial configuration should accurately reflect the connection positions and accuracy between the lower leg, motor, upper leg, ankle, etc., and should also ensure that no interference occurs between structural members when the robot performs any movement gait.

[0020] In step (3), a lightweight lower leg model is reconstructed using a topology design method based on the principles of maximum stiffness and minimum material, and the reconstructed lightweight lower leg model is a continuum, and the reconstructed lightweight lower leg model reflects the material distribution characteristics obtained by finite element simulation of the structural member.

[0021] In step (4), for the reconstructed lightweight lower leg model, the basic thickness of the outer case is 2 mm, the core part is made watermarked, and the core part is replaced with an equal-density dot matrix structure; In step (5), a variable thickness design is performed for the case based on the finite element calculation results, i.e., a variable thickness area is set near the inner surface of the case, and when the equivalent stress at that location is large, the variable thickness is increased, and when the equivalent stress is small, the variable thickness is decreased; In step (6), a change in the side length of the unit cell or the diameter of the rod is designed for the dot matrix structure of the core portion, and the change in the side length of the unit cell or the diameter of the rod is set based on a function related to the spatial position of the side length of the unit cell or the diameter of the rod by setting parameters in a software GUI language or by editing code in a programming software; In step (7), the topology design results are dynamically iterated to obtain a nearly uniform stress field. The thin wall thickness and the dot matrix density of the core are mapped according to the stress field simulation results. After the first mapping is completed, the stress field of the new model is calculated and then the model parameters are iteratively optimized until the difference between the maximum and minimum stresses in the stress field is less than 50 MPa.

[0022] This method can realize the design of high strength and light weight of robot structural members, and the weight reduction effect reaches almost the theoretical limit.

[0023] The operating principle of the present invention is that the ultimate goal of lightweighting a structural component is to achieve a "uniform stress field," i.e., the difference between the maximum and minimum stresses in the structural component's stress field during application and operation is within a narrow range, resulting in a uniform stress field. To achieve this goal, a macro-micro synergistic design is required. By using a macro topology design, material can be reduced in areas with low stress and reserved in areas with high stress. Based on the macro layout, areas with relatively low internal stress can be designed as a dot matrix, and the density of the dot matrix can be adjusted according to the magnitude of the stress. This macro-micro synergistic design allows the structural component to maintain precision at the connection positions of the structural components while significantly reducing the weight of the structure.

[0024] The key point of this invention is to design a robot's lower leg structure using a "variable thickness case + variable density dot matrix" design method, reducing the weight of the lower leg by 30% compared to machined components. The outer surface of the lower leg is a continuous case with variable thickness, and the thickness of the case changes according to the magnitude of stress at that point: the greater the stress, the thicker the case becomes, and the smaller the stress, the thinner the case becomes. The density of the dot matrix in the core also changes according to the magnitude of stress: the greater the stress, the denser the dot matrix. The density of the dot matrix can change depending on the size of the cells or the diameter of the rods in the cells.

[0025] Example 2 In a robot shank model manufactured by a topology design method for thin-walled macro-micro synergy, the shank model has four topology shank tubes 5, a plurality of first short columns 52 of the topology shank and second long columns 53 of the topology shank tubes 5 are connected between two adjacent topology shank tubes 5, the bottoms of the four topology shank tubes 5 are connected at a single point, a bearing mounting surface 3 is connected to the tips of two of the four topology shank tubes 5, a motor mounting plate 2 is connected to the tips of the remaining two topology shank tubes 5, a wiring hole 7 of the topology shank is provided on the bearing mounting surface 3, a surface case 8 of the topology shank is provided on the surface of the topology shank tubes 5, a partial thickened area 81 for the case connection hole is provided on the surface case 8 of the topology shank, and a core dot matrix or a variable density dot matrix 10 is provided in the core part of the topology shank tube 5.

[0026] Based on the design practice of robot structural components, this paper summarizes a method for improving the lightweight and high-strength performance of connecting components, namely, a synergistic design method using a variable density dot matrix and a variable thickness case. In this method, the macro topology layout can achieve lightweight and high aesthetics. The micro topology layout is expressed as a spatial dot matrix, and is further lightweight based on the macro topology layout.

[0027] The contents described in the examples of this specification are merely a list of ways of realizing the concept of the invention, and the scope of protection of the present invention should not be considered limited to the specific forms described in the examples. The scope of protection of the present invention also includes equivalent technical means that a person skilled in the art can come up with based on the concept of the present invention. [Explanation of symbols]

[0028] 1 Early model crural canal 2 Motor mounting plate 21 Motor removal plate 3 Bearing mounting surface 4 Wiring hole 5 Topological lower leg canal 51 Topological lower leg first long column 52 Topological first short column of the lower leg 53 Topological lower leg second long column 54 Topological lower leg crosspiece 6 Topological lower leg bottom 7 Topology lower leg wiring holes 8 Topology Lower Leg Surface Case 81 Partially thickened area of ​​case connection hole 9 Core dot matrix 10 Variable Density Dot Matrix

Claims

1. A topology design method for macro-micro synergy of a thin-walled structure, comprising steps (1) to (7): In the step (1), two gaits are extracted as two types of movement situations based on the robot's motion process, movement situation 1 is a gait in which the robot stands on one foot and the other foot touches the ground, and movement situation 2 is a gait in which the robot stands up from a low position to a high position, In the step (2), the movement situation 1 and the movement situation 2 are combined to design an initial lower leg model and perform finite element calculations; In the step (3), a lightweight lower leg model is reconstructed by a topology design method based on the principle of maximum stiffness and minimum material; In the step (4), for the reconstructed lightweight lower leg model, the basic thickness of the outer case is maintained at 2 mm, the core part is made watermarked, and the core part is replaced with a dot matrix structure; In step (5), a variable thickness design is performed on the case based on the finite element calculation result, i.e., a variable thickness area is set near the inner surface of the case, and when the equivalent stress at the variable thickness area is large, the variable thickness is increased, and when the equivalent stress is small, the variable thickness is decreased; In the step (6), a change in the side length of the unit cell or the diameter of the rod is designed for the dot matrix structure of the core portion, and the change in the diameter of the unit cell or the rod is set based on a function related to the spatial position of the side length of the unit cell or the diameter of the rod by setting parameters in a software GUI language or by editing code in a programming software; In step (7), the topology design results are dynamically iterated to obtain a nearly uniform stress field. A topology design method for macro-micro synergy of a thin-walled structure, characterized by:

2. In step (2), the input of the combined load is three times or more of the user's own weight when standing up and the peak torque value at the knee position when getting up. The topology design method for macro-micro synergy of thin-walled structures according to claim 1.

3. The reconstructed lightweight model in step (3) is a continuum, and the reconstructed lightweight lower leg model reflects the material distribution characteristics of the structural member through finite element simulation. The topology design method for macro-micro synergy of thin-walled structures according to claim 1.

4. In the step (4), the thickness of the outer case is 2 mm, and the core part is a dot matrix with equal density. The topology design method for macro-micro synergy of thin-walled structures according to claim 1.

5. The relationship between the thickness of the thin wall and the density of the dot matrix in the core is mapped based on the stress field simulation results. The topology design method for macro-micro synergy of thin-walled structures according to claim 4.

6. After the first mapping is completed, the stress field of the new model is calculated and then the model parameters are iteratively optimized until the difference between the maximum and minimum stresses in the stress field is less than 50 MPa. The topology design method for macro-micro synergy of thin-walled structures according to claim 5.

7. A robot lower leg structural member manufactured by the topology design method of macro-micro synergy for a thin-walled structure according to any one of claims 1 to 6, The device includes four topological crus tubes (5), and a plurality of first short columns (52) of the topological crus and second long columns (53) of the topological crus are connected between two adjacent topological crus tubes (5); The bottoms of the four topological crural tubes (5) are connected at one point; A bearing mounting surface (3) is connected to the tip of two of the four topology lower leg tubes (5), and a motor mounting plate (2) is connected to the tip of the remaining two topology lower leg tubes (5); The mounting surface (3) of the bearing is provided with a wiring hole (7) for the topology lower leg; A surface case (8) of the topology shank is provided on the surface of the topology shank tube (5), and a partial thickening area (81) of the case connection hole is provided in the surface case (8) of the topology shank. The core of the topology crural canal (5) is provided with a core dot matrix or a variable density dot matrix (10). A robot lower leg structural member characterized by:

Images