Constant force structure for robot

Abstract

The invention relates to the field of constant force structures, in particular to a constant force structure for a robot. A connecting rod is arranged in a limiting shell, first elastic pieces are arranged on the two sides of the connecting rod correspondingly, the top of a second elastic piece is connected with the bottom of the connecting rod, and a connecting rope is arranged at the top of the connecting rod; in the process that the connecting rope pulls the connecting rod until the first elastic piece is horizontal, the first elastic piece continuously compresses and applies the first force to the connecting rod as downward pushing force, the second elastic piece is in a stretching state, and then the second force applied to the connecting rod as downward pulling force, so that the resultant force is not changed in a specific movement interval, and the movement speed is increased. When the connecting rope continuously pulls the connecting rod, the first force applied to the connecting rod by the first elastic pieces is gradually reduced until the first elastic pieces are horizontal and have no vertical acting force at the moment, the connecting rod is continuously pulled by the connecting rope, the first force applied to the connecting rod by the first elastic pieces on the two sides is upward pushing force, and the second force applied to the connecting rod by the second elastic pieces is downward pulling force; and the resultant force is not changed in a specific motion interval.

Description

Technical Field

[0001] The present application relates to the technical field of constant force structures, and in particular to a constant force structure for a robot. Background Art

[0002] In mechanical design and engineering applications, constant force structures have important application value in many fields, especially in situations where precise force control is required, such as precision instruments, automation equipment, medical devices, robotics, and vibration isolation systems. The core goal of constant force structures is to provide approximately constant output force within a certain displacement range, thereby ensuring the stability and predictability of the system.

[0003] Constant force structures have a wide range of applications. For example, in precision measurement and processing equipment, constant force structures can ensure that the force during the processing remains stable, thereby improving processing accuracy and repeatability; in automated assembly lines, constant force structures can be used to control the force during the assembly process to avoid assembly failure or part damage due to excessive or insufficient force; in surgical robots or rehabilitation equipment, constant force structures can ensure precise force control during operation and reduce unnecessary harm to patients; in systems that require vibration isolation, constant force structures can provide stable support force to reduce the impact of external vibrations on the system.

[0004] The Chinese Patent Network discloses "a pulling structure and a flexible surgical robot", with the announcement number CN117257448A, which records that the passive pulling unit is actively pulled by the active pulling unit, so that the driving disk is rotated correspondingly by the second passive pulling rope, and then the elastic member is compressed or actively relaxed by the first passive pulling rope transmission. The present solution sets the driving disk between the first passive pulling rope and the second passive pulling rope, and sets the connection positions of the first passive pulling rope and the second passive pulling rope on the driving disk in a special manner, that is, the driving disk has a hinge end, a first connecting end and a second connecting end distributed in a triangular shape, one end of the first passive pulling rope is connected to the side of the elastic member away from the driving disk, and the other end is connected to the first connecting end, one end of the second passive pulling rope is connected to the second connecting end, and the other end of the second passive pulling rope is connected to the corresponding part of the terminal instrument module. When the second passive pulling rope is subjected to the pulling force of the active pulling unit and pulls the driving disk to rotate, the driving disk can always be subjected to approximately constant force traction during the rotation process, that is, the pulling force of the second passive pulling rope during the traction process is relatively constant.

[0005] According to the above description, it can be further known that this is a constant force structure, where there is friction between the traction rope and the pulley, and between the slider and the chute. The friction force makes it necessary to overcome a greater force during the compression process, while a smaller driving force is provided during the return journey, resulting in different forward and backward forces. Moreover, the friction force increases the traction force required by the active traction unit, causing wear and affecting the precise control of the constant force structure. At the same time, its structure is complex, which may require a relatively high technical level during the production, manufacturing, installation and maintenance processes, increasing the production, use and maintenance costs. Summary of the Invention

[0006] This application provides a constant force structure for a robot to solve the technical problems that the inventor recognized. The friction force makes it necessary to overcome a greater force during the compression process, while a smaller driving force is provided during the return journey, resulting in different forward and backward forces. Moreover, the friction force increases the traction force required by the active traction unit, causing wear and affecting the precise control of the constant force structure. At the same time, its structure is complex, which may require a relatively high technical level during the production, manufacturing, installation and maintenance processes, increasing the production, use and maintenance costs.

[0007] This application provides a constant force structure for a robot, including a limit housing. An adjusting rod is arranged inside the limit housing. One elastic member is arranged on each side of the adjusting rod, and the other end of the elastic member is connected to the inner wall of the limit housing. A second elastic member is arranged at the bottom of the limit housing, and the top of the second elastic member is connected to the bottom of the adjusting rod. A connecting rope is arranged at the top of the adjusting rod, and the other end of the connecting rope extends outside the limit housing. The first elastic member exerts a first force on the adjusting rod, and the second elastic member exerts a second force on the adjusting rod.

[0008] In any of the above technical solutions, further, the first elastic member is wavy.

[0009] In any of the above technical solutions, further, the first elastic member is inclined relative to the adjusting rod.

[0010] In any of the above technical solutions, further, the number of the first elastic members is an integer multiple of the number of the second elastic members.

[0011] In any of the above technical solutions, further, a plurality of the first elastic members are symmetrically arranged on both sides of the adjusting rod.

[0012] In any of the above technical solutions, further, the first elastic member adopts an integrally formed structure.

[0013] In any of the above technical solutions, further, the second elastic member adopts an integrally formed structure.

[0014] In any of the above technical solutions, further, an opening is formed inside the limit housing, and the other end of the connecting rope passes through the opening.

[0015] In any of the above technical solutions, further, the material of the first elastic member is selected from any one of polylactide, nylon, ABS plastic, and PETG plastic.

[0016] In any of the above technical solutions, further, the material of the second elastic member is selected from any one of polylactide, nylon, ABS plastic, and PETG plastic.

[0017] The beneficial effects of this application are mainly as follows: In the constant force range, in the initial state, both the first elastic member and the second elastic member are in a relaxed state and do not exert force on the connecting rod. During the process of the connecting rope pulling the connecting rod until the first elastic member is in a horizontal state, the first elastic member is continuously compressed and exerts a first force on the connecting rod, which is a downward thrust. And the second elastic member is in a stretched state, and then exerts a second force on the connecting rod, which is a downward pulling force. During this process, the resultant force of the first force and the second force remains unchanged within a specific motion range. The first force exerted by the first elastic member on the connecting rod gradually becomes smaller until the first elastic member is in a horizontal state. At this time, the first elastic member has no vertical direction acting force. As the connecting rope continues to pull the connecting rod, the first force exerted by the first elastic members on both sides on the connecting rod is an upward thrust, and the second elastic member exerts a second force on the connecting rod, which is a downward pulling force. At this time, the resultant force of the first force and the second force remains unchanged within a specific motion range, thus realizing the constant force effect. Compared with the prior art, the production and maintenance costs drop significantly, and at the same time, the influence of friction on the constant force is reduced, thereby ensuring the accuracy of the device.

[0018] It should be understood that both the foregoing general description and the following detailed description are for the purpose of illustration and example only and do not necessarily limit this application. The accompanying drawings incorporated in and constituting a part of this specification illustrate the subject matter of this application. At the same time, the specification and the drawings are used to explain the principles of this application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 Schematic diagram of the constant force structure of the embodiment of this application Figure 1 ; Figure 2 Schematic diagram of the constant force structure of the embodiment of this application Figure 2 ; Figure 3 Schematic diagram of the constant force structure in the embodiment of the present application Figure 3 ; Figure 4 Experimental curve result diagram in the embodiment of the present application.

[0021] Icon: 100 - Limit housing; 101 - Connecting rod; 102 - First elastic member; 103 - Second elastic member; 104 - Connecting rope. Specific implementation manner

[0022] The technical solutions of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present application.

[0023] All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0024] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present application. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0025] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0026] Please refer to Figure 1 、 Figure 2 and Figure 3, in one or more embodiments, a constant force structure for a robot is provided, which includes a limit housing 100. A connecting rod 101 is arranged inside the limit housing 100. On both sides of the connecting rod 101, first elastic members 102 are respectively arranged. The other ends of the first elastic members 102 are connected to the inner wall of the limit housing 100. A second elastic member 103 is arranged at the bottom of the limit housing 100. The top of the second elastic member 103 is connected to the bottom of the connecting rod 101. A connecting rope 104 is arranged at the top of the connecting rod 101. The other end of the connecting rope 104 extends to the outside of the limit housing 100. The first elastic member 102 exerts a first force on the connecting rod 101, and the second elastic member 103 exerts a second force on the connecting rod 101. An opening is formed inside the limit housing 100, and the other end of the connecting rope 104 passes through the opening.

[0027] In this embodiment, within the constant force range, in the initial state, both the first elastic member 102 and the second elastic member 103 are in a relaxed state and do not exert forces on the connecting rod 101. When the connecting rope 104 pulls the connecting rod 101 until the first elastic member 102 is in a horizontal state, the first elastic member 102 is continuously compressed and exerts a first force on the connecting rod 101, which is a downward thrust. While the second elastic member 102 is in a stretched state, and thus exerts a second force on the connecting rod 102, which is a downward pulling force. During this process, the first force and the second force achieve a constant resultant force within a specific motion range. The first force exerted by the first elastic member 102 on the connecting rod 101 gradually becomes smaller until the first elastic member 102 is in a horizontal state. At this time, the first elastic member 102 has no vertical direction acting force. As the connecting rope 104 continues to pull the connecting rod 101, the first elastic members 102 on both sides exert an upward thrust on the connecting rod 101, and the second elastic member 103 exerts a second force on the connecting rod 101, which is a downward pulling force. At this time, the first force and the second force achieve a constant resultant force within a specific motion range, thereby achieving the constant force effect. Compared with the prior art, the production and maintenance costs drop significantly, and at the same time, the influence of friction on the constant force is reduced, thereby ensuring the accuracy of the device. As the connecting rope 104 continues to pull the connecting rod 101, at this time, it exceeds the constant force range, and both the first force exerted by the first elastic member 102 on the connecting rod 101 and the second force exerted by the second elastic member 103 on the connecting rod 101 are downward pulling forces. The setting of the opening reduces the friction between the limit housing 100 and the connecting rope 104, and thus reduces the influence of friction on the change of the constant force. It should be noted that in this application, the limit housing 100 is used to fix the positions of the first elastic member 102 and the second elastic member 103. In the actual use process, if necessary, the limit housing can be not used, and the first elastic member 102 and the second elastic member 103 can be installed at appropriate positions.

[0028] In this embodiment, the calculation formula in this application is as follows, where k1 is the elastic coefficient of the first elastic member, k2 is the elastic coefficient of the second elastic member, a is the horizontal distance between the two ends of the first elastic member, and b is the height difference between the two ends of the first elastic member. It is the deformation distance. It can be seen from the Matlab simulation that when k2 / k1 = 3.83, a = 30, and b = 16.3, the tensile force F is approximately constant during the range of 11.5 to 19.9.

[0029] Please refer to Figure 1 、 Figure 2 and Figure 3 In some embodiments, the first elastic member 102 is wavy, the first elastic member 102 is inclined relative to the connecting rod 101, the number of the first elastic members 102 is an integer multiple of the number of the second elastic members 103, and multiple first elastic members 102 are symmetrically arranged on both sides of the connecting rod 101.

[0030] It should be noted that Figure 4 This is the experimental curve result diagram of the device, where the x-axis is the deformation length with the unit of mm, and the y-axis is the strain force with the unit of N.

[0031] In this embodiment, the first elastic member 102 and the second elastic member 103 are parameterized to facilitate adaptation to the usage requirements in different environments. By adjusting the dimensions of the first elastic member 102 and the second elastic member 103, a constant force range that better fits the usage requirements can be achieved. At the same time, by changing the thicknesses of the first elastic member 102 and the second elastic member 103, the thrust or tensile force on the connecting rod 101 in different states can be changed. Meanwhile, the dimensions of the constant force structure are changed proportionally, and then the displacement stroke of the connecting rod 101 is changed. In the formula, a and b directly affect the inclination angle of the first elastic member 102. The constant force magnitude can be changed by changing the inclination angle of the first elastic member 102, so as to adapt to the usage requirements of different devices, and it has broad application prospects in many fields such as precision instruments, automation equipment, medical devices, vibration isolation systems, electronic devices, automotive industry, aerospace, industrial machinery, energy equipment, and scientific research experimental equipment.

[0032] Please refer to Figure 1 、 Figure 2 and Figure 3 In some embodiments, the first elastic member 102 adopts an integrally formed structure, the second elastic member 103 adopts an integrally formed structure, the material of the first elastic member 102 is selected from any one of poly(lactic acid), nylon, ABS plastic, and PETG plastic, and the material of the second elastic member 103 is selected from any one of poly(lactic acid), nylon, ABS plastic, and PETG plastic.

[0033] In this embodiment, the materials of the first elastic member 102 and the second elastic member 103 in the present application include but are not limited to the above materials. In the experiment, when the first elastic member 102 and the second elastic member 103 are made of poly(lactic acid), the force change is 5%. When the first elastic member 102 and the second elastic member 103 are made of nylon, the force change is 2%. When the first elastic member 102 and the second elastic member 103 are made of ABS plastic, the force change is 2%. When the first elastic member 102 and the second elastic member 103 are made of PETG plastic, the force change is 2%. Therefore, the first elastic member 102 and the second elastic member 103 in the present application preferably adopt poly(lactic acid) materials. It should be noted that the first elastic member 102 and the second elastic member 103 in the present application adopt an integrally formed structure, which can be 3D printed or injection molded. The constant force stroke can be changed by scaling up proportionally. There are two ways to change the constant force. One is to change the stiffness of the first elastic member 102 and the second elastic member 103, and the other is to change the overall thickness of the first elastic member 102 and the second elastic member 103. For example, when using 3D printing to change the thickness of the first elastic member 102 and the second elastic member 103, the number of printing layers is changed.

[0034] In this embodiment, the experimental printing material is PETG-CF, and the printing machine is Creality 3D K2 Plus. PETG-CF is a material composed of PETG (polyethylene terephthalate) and carbon fiber composite. During the stretching process from 9.6 to 19.5 mm, the force remains unchanged at around 18.6 N, and the force change is only 1.6%, while the effective constant force stroke is 50.8% (the calculation method is (19.5 - 9.6) / 19.5).

[0035] Specifically, the working principle of a constant force structure for a robot provided by the present application is: In the constant force range, in the initial state, both the first elastic member 102 and the second elastic member 103 are in a relaxed state and do not apply force to the connecting rod 101. When the connecting rope 104 pulls the connecting rod 101 until the first elastic member 102 is in a horizontal state, the first elastic member 102 is continuously compressed and applies a first force to the connecting rod 101, which is a downward thrust. The second elastic member 102 is in a stretched state, and then applies a second force to the connecting rod 102, which is a downward pull. During this process, the first force and the second force achieve a constant resultant force in a specific motion range. The first force applied by the first elastic member 102 to the connecting rod 101 gradually becomes smaller until the first elastic member 102 is in a horizontal state. At this time, the first elastic member 102 has no vertical direction force. As the connecting rope 104 continues to pull the connecting rod 101, the first force applied by the first elastic members 102 on both sides to the connecting rod 101 is an upward thrust, and the second elastic member 103 applies a second force to the connecting rod 101, which is a downward pull. At this time, the first force and the second force achieve a constant resultant force in a specific motion range, thus achieving the constant force effect. As the connecting rope 104 continues to pull the connecting rod 101, at this time, it exceeds the constant force range, and the first force applied by the first elastic member 102 to the connecting rod 101 and the second force applied by the second elastic member 103 to the connecting rod 101 are both downward pulling forces; The first elastic member 102 and the second elastic member 103 are parameterized to facilitate adaptation to the usage requirements in different environments. By adjusting the thickness of the first elastic member 102 and the second elastic member 103, the elastic coefficients of the first elastic member 102 and the second elastic member 103, and the inclination angle of the first elastic member 102, the magnitude of the constant force can be changed, thereby adapting to the usage requirements of different devices. It has broad application prospects in many fields such as precision instruments, automation equipment, medical devices, vibration isolation systems, electronic devices, automotive industry, aerospace, industrial machinery, energy equipment, and scientific research experimental equipment.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A constant force structure for a robot, characterized in that, It includes a limiting outer shell, inside which there is a connecting rod. On both sides of the connecting rod, there are respectively first elastic members, and the other ends of the first elastic members are connected to the inner wall of the limiting outer shell. At the bottom of the limiting outer shell, there is a second elastic member, and the top of the second elastic member is connected to the bottom of the connecting rod. At the top of the connecting rod, there is a connecting rope, and the other end of the connecting rope extends to the outside of the limiting outer shell. The first elastic member exerts a first force on the connecting rod, and the second elastic member exerts a second force on the connecting rod.

2. The constant force structure for a robot according to claim 1, wherein The first elastic member is wavy.

3. The constant force structure for a robot according to claim 1, wherein, The first elastic member is inclined relative to the connecting rod.

4. A constant force structure for a robot according to claim 1, characterized in that, The number of the first elastic members is an integer multiple of the number of the second elastic members.

5. The constant force structure for a robot according to claim 4, characterized in that A plurality of the first elastic members are symmetrically arranged on both sides of the connecting rod.

6. The constant force structure for a robot according to claim 1, characterized in that, The first elastic member adopts an integrally formed structure.

7. A constant force structure for a robot according to claim 1, characterized in that, The second elastic member adopts an integrally formed structure.

8. The constant force structure for a robot according to claim 1, wherein, There is an opening inside the limiting outer shell, and the other end of the connecting rope passes through the opening.

9. The constant force structure for a robot according to claim 1, wherein, The material of the first elastic member is selected from any one of polylactide, nylon, ABS plastic, and PETG plastic.

10. The constant force structure for a robot according to claim 1, wherein The material of the second elastic member is selected from any one of polylactide, nylon, ABS plastic, and PETG plastic.

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