Active variable stiffness joint and robot based on powder electrostatic adsorption

Abstract

The present invention provides an active variable stiffness joint and robot based on electrostatic adsorption of powder, belonging to the technical field of variable stiffness joints. The problem of complex structure and low load-bearing capacity of variable stiffness joints is solved. It includes a cut-out flexible structure, charged powder, an electrostatic suction cup, an electrostatic shielding outer net, an electrostatic shielding inner net and an outer diaphragm. A boss structure is connected to each end of the cut-out flexible structure. A number of electrostatic suction cups are evenly arranged on the circumferential surface of each boss structure. An electrostatic shielding inner net is sleeved on the cut-out flexible structure, an electrostatic shielding outer net is sleeved outside the electrostatic shielding inner net, charged powder is arranged between the electrostatic shielding inner net and the electrostatic shielding outer net, and an outer diaphragm is arranged outside the electrostatic shielding outer net. The charged powder includes a number of semiconductor particles, which flow in the joint, and the electrostatic field is formed by controlling the electrostatic suction cups on both sides to change the fluidity between the semiconductor particles, thereby changing the stiffness of the joint. The present invention is suitable for robots or wearable exoskeletons.

Description

Technical Field

[0001] The invention belongs to the field of variable stiffness joint electromechanical system design, and in particular relates to an active variable stiffness joint and a robot based on powder electrostatic adsorption. Background Art

[0002] Variable stiffness joints are devices that can actively or passively adjust joint stiffness. They have high energy utilization, good environmental adaptability, and human-computer interaction safety. They are currently widely used in fields such as robots and wearable exoskeletons.

[0003] At present, the main control methods of joint stiffness can be divided into three types: mechanical control, electromagnetic control, and new material control. Mechanical control relies on sophisticated mechanical design schemes to control the internal force of the joint through springs, ropes, airbags and other components, thereby changing the stiffness characteristics of the mechanism. Electromagnetic control mostly relies on dielectric elastic materials to control joint stiffness, and new material control joints are designed based on new materials such as shape memory alloys and temperature control alloys. Different forms of variable stiffness joints vary greatly in terms of load-bearing capacity, stiffness adjustment range, structural compactness, response speed, structural life, etc., and all have defects to varying degrees. Mechanical variable stiffness joints are difficult to miniaturize due to their complex structure and poor compactness. The load-bearing material of electromagnetic variable stiffness joints is dielectric elastomer, which is a flexible material, so its load-bearing capacity is relatively weak. The technical maturity of new material variable stiffness joints is low, and their performance in terms of load-bearing capacity, response speed and structural life is relatively poor. Therefore, it is very necessary to design a new variable stiffness joint structure to solve the above problems. Summary of the invention

[0004] In view of this, the invention aims to propose an active variable stiffness joint based on powder electrostatic adsorption to solve the problem of complex structure and low load-bearing capacity of variable stiffness joints. The invention creates an active variable stiffness joint based on powder electrostatic adsorption, which uses an electrostatic field to change the agglomeration effect and fluidity between powder particles, thereby realizing active control of joint stiffness. It has the advantages of strong load-bearing capacity, large stiffness adjustment range, compact structure, fast response speed, and long life.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] An active variable stiffness joint based on electrostatic adsorption of powders, comprising a notched flexible structure, charged powders, an electrostatic suction cup, an electrostatic shielding outer net, an electrostatic shielding inner net and an outer diaphragm, wherein the notched flexible structure is a hollow cylindrical structure, a plurality of arc-shaped notches are evenly arranged on the surface of the hollow cylindrical structure, a boss structure is connected to each of the two ends of the notched flexible structure, a plurality of electrostatic suction cups are evenly arranged on the circumferential surface of each boss structure, an electrostatic shielding inner net is sleeved on the notched flexible structure, an electrostatic shielding outer net is sleeved outside the electrostatic shielding inner net, two ends of the electrostatic shielding outer net extend to the boss structures on the corresponding sides so that the electrostatic shielding outer net completely covers all the electrostatic suction cups, charged powders are arranged between the electrostatic shielding inner net and the electrostatic shielding outer net, an outer diaphragm is arranged outside the electrostatic shielding outer net, and two ends of the outer diaphragm are respectively fixed to the boss structures on both sides of the notched flexible structure;

[0007] The charged powder includes a number of semiconductor particles, which flow in the joint. The electrostatic field formed by controlling the electrostatic suction cups on both sides changes the fluidity between the semiconductor particles, thereby changing the stiffness of the joint.

[0008] Furthermore, the plurality of arc-shaped cutouts on the cutout-type flexible structure are arranged along the hollow cylindrical structure, and two adjacent arc-shaped cutouts are arranged in a staggered manner.

[0009] Furthermore, the length of each arc-shaped cutout is greater than the length of a half circumference of the cylinder at the corresponding position, and less than the circumference of the cylinder at the corresponding position.

[0010] Furthermore, the cut-out flexible structure, the electrostatic shielding inner net and the electrostatic shielding outer net are all made of elastic metal materials.

[0011] Furthermore, the outer diaphragm completely covers the electrostatic shielding outer net, and the two ends of the outer diaphragm are each fixed to the boss structure on the corresponding side by a binding belt.

[0012] Furthermore, the boss structure is a truncated cone structure.

[0013] Furthermore, the electrostatic chuck is evenly mounted on the surface of the boss structure and is arranged close to the small diameter end of the boss structure.

[0014] Furthermore, a groove cooperating with the strapping belt is provided on the circumference of the large diameter end of the boss structure.

[0015] Furthermore, the electrostatic suction cup is fixed to the boss structure by electrostatic suction cup bolts, and both ends of the cut-out flexible structure are welded to the corresponding boss structure; a number of boss fixing bolts connected to the external parts of the joint are evenly arranged on the large-diameter end surface of the boss structure.

[0016] Another object of the present invention is to provide a robot comprising a plurality of active variable stiffness joints based on electrostatic adsorption of powder as described above.

[0017] Compared with the prior art, the active variable stiffness joint based on powder electrostatic adsorption created by the present invention has the following beneficial effects:

[0018] (1) The active variable stiffness joint based on electrostatic adsorption of powders created by the present invention provides a flexible incision structure that can achieve two-degree-of-freedom bending motion of the joint;

[0019] (2) The active variable stiffness joint based on powder electrostatic adsorption created by the present invention realizes active adjustment of joint stiffness by providing an electric field and powder electrostatic adsorption by an electrostatic chuck;

[0020] (3) The present invention creates an active variable stiffness joint based on electrostatic adsorption of powder. Through a variable stiffness mechanism designed based on charged powder, the charged powder is used as a flexible joint filler with a large pressure-bearing range, which significantly improves the joint's structural compactness, load-bearing capacity and service life, and improves the stiffness adjustment range and response speed of the variable stiffness joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0022] Figure 1 This is a schematic diagram of the overall structure of an active variable stiffness joint based on electrostatic adsorption of powders according to an embodiment of the present invention;

[0023] Figure 2 A schematic diagram of the internal structure of an active variable stiffness joint based on electrostatic adsorption of powders according to an embodiment of the present invention;

[0024] Figure 3 A cross-sectional view of an active variable stiffness joint based on electrostatic adsorption of powders according to an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of the main structure of an active variable stiffness joint based on electrostatic adsorption of powders described in an embodiment of the invention;

[0026] Figure 5 A schematic diagram of a notched flexible structure in an active variable stiffness joint based on electrostatic adsorption of powders according to an embodiment of the present invention;

[0027] Figure 6A schematic diagram of a boss structure in an active variable stiffness joint based on electrostatic adsorption of powders according to an embodiment of the present invention;

[0028] Figure 7 A schematic diagram of the structure of an electrostatic shielding inner net in an active variable stiffness joint based on electrostatic adsorption of powders according to an embodiment of the present invention;

[0029] Figure 8 A schematic diagram of the structure of an electrostatic shielding outer network in an active variable stiffness joint based on electrostatic adsorption of powders according to an embodiment of the present invention;

[0030] Fig. 9 A schematic diagram of the structure of a strapping belt in an active variable stiffness joint based on electrostatic adsorption of powders according to an embodiment of the present invention;

[0031] Fig.10 This is a schematic diagram of an active variable stiffness joint based on electrostatic adsorption of powders as described in an embodiment of the present invention under the action of external forces / torques.

[0032] Description of reference numerals:

[0033] 1. Boss structure; 2. Strapping belt; 3. Outer diaphragm; 4. Electrostatic chuck; 5. Electrostatic shielding outer net; 6. Electrostatic shielding inner net; 7. Charged powder; 8. Notch-type flexible structure; 9. Boss fixing bolts; 10. Electrostatic chuck fixing bolts. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention 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 cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0036] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0037] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] like Figure 1-Figure 9 As shown, an active variable stiffness joint based on electrostatic adsorption of powders comprises a notched flexible structure 8, charged powders 7, electrostatic suction cups 4, an electrostatic shielding outer net 5, an electrostatic shielding inner net 6 and an outer diaphragm 3, wherein the notched flexible structure 8 is a hollow cylindrical structure, and a plurality of arc-shaped notches are evenly arranged on the surface of the hollow cylindrical structure, a boss structure 1 is connected to each of the two ends of the notched flexible structure 8, and a plurality of electrostatic suction cups 4 are evenly arranged on the circumferential surface of each boss structure 1, an electrostatic shielding inner net 6 is sleeved on the notched flexible structure 8, an electrostatic shielding outer net 5 is sleeved outside the electrostatic shielding inner net 6, and both ends of the electrostatic shielding outer net 5 extend to the corresponding side boss structures 1 so that the electrostatic shielding outer net 5 completely covers all the electrostatic suction cups 4, a charged powder 7 is arranged between the electrostatic shielding inner net 6 and the electrostatic shielding outer net 5, an outer diaphragm 3 is arranged outside the electrostatic shielding outer net 5, and both ends of the outer diaphragm 3 are respectively fixed to the boss structures 1 on both sides of the notched flexible structure 8;

[0039] The charged powder 7 includes a large number of semiconductor particles. The charged powder flows in the joint and fills the gap between the electrostatic shielding outer network and the electrostatic shielding inner network. The semiconductor particles are coated with a ceramic layer on the outer surface of brass, and the ceramic layer can be a silicon carbide layer or an aluminum nitride layer. The electrostatic field is formed by controlling the electrostatic suction cups 4 on both sides to change the fluidity between the semiconductor particles and thereby change the stiffness of the joint.

[0040] The internal incision-type flexible structure 8 of the present application simulates joint movement through structural deformation, ensures the basic stiffness requirements of the joint, provides support for the joint mechanism, and enables the joint to achieve two-degree-of-freedom bending movement; the charged powder inside the joint is composed of a large amount of semiconductor granular material (powder particles), and the charged powder flows in the joint to assist in load bearing; the electrostatic suction cup adjusts the "polarization" characteristics of the powder by controlling its electrode voltage, thereby changing the agglomeration effect and friction characteristics between the powder particles, and further controlling the stiffness of the mechanism.

[0041] The present application ensures the basic structural strength and stiffness of the variable stiffness joint by using a cut-out structure, and utilizes powder as a stiffness adjustment medium to improve the bearing capacity; and actively changes the stiffness of the joint by using an electrostatic suction cup to control the polarity of the charged powder, which helps to speed up the stiffness adjustment.

[0042] The plurality of arc-shaped cutouts on the cutout-type flexible structure 8 are arranged along the hollow cylindrical structure, and the adjacent arc-shaped cutouts are arranged in a staggered manner. The length of each arc-shaped cutout is greater than the length of the semicircle of the cylinder at the corresponding position, and less than the circumference of the cylinder at the corresponding position. With such an arrangement, the cutout-type structure can simulate joint motion through structural deformation, ensure the basic stiffness requirements of the joint, provide support for the mechanism, and realize two-degree-of-freedom bending motion.

[0043] The cut-out flexible structure 8, the electrostatic shielding inner net 6 and the electrostatic shielding outer net 5 are all made of elastic metal materials such as beryllium bronze and manganese steel. Such a configuration can prevent powder leakage and form an electrostatic shield.

[0044] The outer membrane 3 completely covers the electrostatic shielding outer net 5, and the two ends of the outer membrane 3 are fixed to the boss structure 1 on the corresponding side by a strapping belt 2. In this way, the variable stiffness joint is sealed, isolated from external environmental interference and does not affect the movement of the joint.

[0045] The boss structure 1 is a truncated cone structure, which is convenient for connecting with the end of the cylindrical cut-out flexible structure 8 on the one hand, and convenient for fixing the outer diaphragm 3 on the other hand, and is conducive to the installation of various components thereon. The electrostatic suction cup 4 is evenly installed on the surface of the boss structure and arranged close to the small diameter end of the boss structure 1. A groove is provided on the circumference of the large diameter end of the boss structure 1 to cooperate with the strapping belt 2. In this way, the outer diaphragm is fixed and the electrostatic suction cup is placed to realize the joint function.

[0046] The electrostatic chuck 4 is fixed to the boss structure 1 by the electrostatic chuck bolt 10, and both ends of the cut-out flexible structure 8 are welded to the corresponding boss structure 1. A number of boss fixing bolts 9 connected to the joint external parts are evenly arranged on the large-diameter end surface of the boss structure 1. Through the above arrangement, the connection between the structures is more firm and stable.

[0047] The active variable stiffness joint based on powder electrostatic adsorption of the present application uses a notched flexible structure 8 to ensure the basic structural strength and stiffness of the variable stiffness joint, and uses powder as a stiffness adjustment medium to improve the bearing capacity; the active variable stiffness joint based on powder electrostatic adsorption of the present application uses an electrostatic suction cup 4 to control the polarity of the charged powder 7 to actively change the stiffness of the joint, which helps to speed up the stiffness adjustment speed.

[0048] The active variable stiffness joint based on powder electrostatic adsorption of the present application utilizes the electrostatic field to change the agglomeration effect and fluidity between powder particles, thereby realizing active control of joint stiffness. It has the advantages of strong load-bearing capacity, large stiffness adjustment range, compact structure, fast response speed and long life.

[0049] The material of the boss structure is Q235 steel, the material of the strapping belt 2 is stainless steel, there are six electrostatic suction cups 4, twelve boss fixing bolts, twenty-four electrostatic suction cup fixing bolts, the material of the boss fixing bolts 9 is 45 steel, and the material of the electrostatic suction cup fixing bolts 10 is 45 steel.

[0050] The variable stiffness working principle of this application is as follows: Fig.10 As shown, under the action of external force / torque, the incision-type flexible structure 8 bends and deforms, and the charged powder 7 flows from the compression side to the tension side under the pressure of the joint wall. In this process, the electrostatic suction cups 4 on both sides of the joint generate voltages of opposite polarity, forming an electrostatic field, polarizing the powder, thereby increasing the attraction and friction between the powders, increasing the flow resistance, and the joint displacement will definitely decrease under the same torque, resulting in an increase in joint stiffness, and the joint stiffness increases with the increase in electric field strength. The electrostatic suction cup 4 and the powder material form an equivalent capacitor, and the capacitance is determined by the mechanism design parameters and the joint angle. Since the electrostatic induction speed is much higher than the mechanical movement speed of the joint, the joint angle can be measured based on the electricity meter connected to the electrostatic suction cup.

[0051] The working process of an active variable stiffness joint based on electrostatic adsorption of powder is as follows: under the action of external force / torque, the incision structure bends and deforms, and the powder flows from the compression side to the tension side under the pressure of the joint wall, such as Fig.10 In this process, the electrostatic suction cups on both sides of the joint generate voltages of opposite polarity, forming an electrostatic field, polarizing the powder, thereby increasing the attraction and friction between the powders. Therefore, the joint stiffness increases with the increase of the electric field strength. When in use, the electric field strength is adjusted according to the joint stiffness requirements, thereby realizing the active variable stiffness joint adjustment and use.

[0052] Another object of the present invention is to provide a robot, which includes a plurality of active variable stiffness joints based on powder electrostatic adsorption as described above. The robot of the present invention has the active variable stiffness joint structure based on powder electrostatic adsorption of the present application, so it also has the characteristics of strong load-bearing capacity, large stiffness adjustment range, compact structure, fast response speed, and long life, and can adapt to more occasions.

[0053] The active variable stiffness joint structure based on powder electrostatic adsorption of the present application can be widely used in fields such as robots and wearable exoskeletons. It has a wide range of applications and also provides a new research direction and new ideas for these two fields.

[0054] The embodiments of the invention disclosed above are only used to help illustrate the invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the invention, so that those skilled in the art can understand and use the invention well.

Claims

1. An active variable stiffness joint based on powder electrostatic adsorption, characterized in that: The invention comprises a notched flexible structure (8), charged powder (7), an electrostatic suction cup (4), an electrostatic shielding outer net (5), an electrostatic shielding inner net (6) and an outer diaphragm (3). The notched flexible structure (8) is a hollow cylindrical structure. A plurality of arc-shaped notches are evenly arranged on the surface of the hollow cylindrical structure. A boss structure (1) is connected to each of the two ends of the notched flexible structure (8). A plurality of electrostatic suction cups (4) are evenly arranged on the circumference of each boss structure (1). An electrostatic shielding inner net (6) is sleeved on the notched flexible structure (8). A net (6) is provided, an electrostatic shielding outer net (5) is sleeved outside the electrostatic shielding inner net (6), two ends of the electrostatic shielding outer net (5) extend to the boss structures (1) on the corresponding sides so that the electrostatic shielding outer net (5) completely covers all the electrostatic suction cups (4), a charged powder (7) is provided between the electrostatic shielding inner net (6) and the electrostatic shielding outer net (5), an outer diaphragm (3) is sleeved outside the electrostatic shielding outer net (5), and two ends of the outer diaphragm (3) are respectively fixed to the boss structures (1) on both sides of the cut-out flexible structure (8); The charged powder (7) includes a number of semiconductor particles, which flow in the joint. The electrostatic field formed by controlling the electrostatic suction cups (4) on both sides changes the fluidity between the semiconductor particles, thereby changing the stiffness of the joint.

2. The active variable stiffness joint based on powder electrostatic adsorption according to claim 1, characterized in that: The plurality of arc-shaped cutouts on the cutout-type flexible structure (8) are arranged along the hollow cylindrical structure, and two adjacent arc-shaped cutouts are arranged in a staggered manner.

3. The active variable stiffness joint based on powder electrostatic adsorption according to claim 2, characterized in that: The length of each arc-shaped cutout is greater than the length of the semicircle of the cylinder at the corresponding position, and less than the circumference of the cylinder at the corresponding position.

4. The active variable stiffness joint based on powder electrostatic adsorption according to claim 1, characterized in that: The incision-type flexible structure (8), the electrostatic shielding inner net (6) and the electrostatic shielding outer net (5) are all made of elastic metal material.

5. The active variable stiffness joint based on powder electrostatic adsorption according to claim 1, characterized in that: The outer diaphragm (3) completely covers the electrostatic shielding outer net (5), and the two ends of the outer diaphragm (3) are fixed to the boss structure (1) on the corresponding side by a binding belt (2).

6. The active variable stiffness joint based on powder electrostatic adsorption according to claim 1, characterized in that: The boss structure (1) is a truncated cone structure.

7. The active variable stiffness joint based on powder electrostatic adsorption according to claim 6, characterized in that: The electrostatic suction cup (4) is evenly mounted on the surface of the boss structure and is arranged close to the small diameter end of the boss structure (1).

8. The active variable stiffness joint based on powder electrostatic adsorption according to claim 6, characterized in that: A groove matching with the binding belt (2) is provided on the circumference of the large diameter end of the boss structure (1).

9. The active variable stiffness joint based on powder electrostatic adsorption according to claim 1, characterized in that: The electrostatic suction cup (4) is fixed to the boss structure (1) by means of an electrostatic suction cup bolt (10), both ends of the cut-out flexible structure (8) are welded to the corresponding boss structure (1), and a plurality of boss fixing bolts (9) connected to the external joint components are evenly arranged on the large-diameter end surface of the boss structure (1).

10. A robot, characterized in that: It comprises several active variable stiffness joints based on powder electrostatic adsorption as described in any one of claims 1-8.

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