Multi-steady and self-locking rotary joints and their usage

Abstract

This invention proposes a multi-stable and self-locking rotary joint and its usage method. The rotary joint includes: a second hinge link, a first hinge link, a flower-shaped cam, a flexible energy storage and self-locking component, and a driver; the second hinge link and the first hinge link are rotatable around the first hinge link; the flower-shaped cam is used to drive the flexible energy storage and self-locking component to move axially, and its outer contour forms multiple peaks and troughs; adjacent troughs are connected by peaks; the first hinge link is fixedly installed, and the flexible energy storage and self-locking component is installed on it; the flexible energy storage and self-locking component can form a self-locking state and an unlocking state of the flower-shaped cam, and includes: a lateral flexible locking mechanism and an axial flexible guiding mechanism; along the axial direction, a flexible connection is formed between the lateral flexible locking mechanism and the rigid frame, and along the lateral direction, a flexible connection is formed between the axial flexible guiding mechanism and the rigid frame; the driver is used to drive the lateral flexible locking mechanism to generate lateral displacement. This invention can simultaneously achieve multi-stable positioning and self-locking, providing a novel solution for the construction of multi-stable variant / folding structures and multi-stable deformable robots.

Description

Technical Field

[0001] This invention belongs to the field of multistable mode realization and non-energy-consuming self-protecting mode technology in the field of robotics, and particularly relates to a multistable and self-locking rotary joint and its usage method. Background Technology

[0002] Rotary joints are widely used in robotic systems and adaptive aerospace structures, allowing for changes in the overall shape of robots or deformable structures through hinge position transformations. However, achieving precise position control and locking for load-bearing tasks requires adding complex position feedback control systems and mechanical locking mechanisms to the hinges. In some fields with limited design space and stringent requirements, the extensive use of rotary joints struggles to meet the system's demands for simplicity, reliability, design space, and weight reduction.

[0003] Therefore, scholars have proposed some bistable rolling joints to construct multistable deformable systems in response to this problem. For example, the paper "A bistable rolling joint for multistable structures" (DOI: 10.1016 / j.mechrescom.2016.11.003) in the journal Mechanics Research Communications proposes a bistable rolling joint based on modifying the geometry of the rolling hinge.

[0004] However, existing rotary joints struggle to achieve multiple stable positions and cannot achieve self-locking of the stable position. This means that deformable systems built using them can only achieve a limited number of stable shapes and are difficult to use under heavy loads. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-stable and self-locking rotary joint and its method of use. This joint can achieve multiple steady-state positions, specifically with steady-state self-locking and locking / releasing functions. The technical solution adopted is as follows:

[0006] This invention addresses the challenges of achieving multiple stable positions, implementing steady-state self-locking functions, and the complexity of locking and releasing mechanisms in hinges. It provides a novel multi-stable self-locking rotary joint based on a flexible flower-shaped cam and a flexible mechanism with energy storage and locking functions. This joint can achieve multiple stable positions, steady-state self-locking functions, and locking and releasing functions.

[0007] Basic principle: This invention is mainly based on two components, namely a rigid flower-shaped cam and a flexible component with energy storage and self-locking "dual function".

[0008] Rigid floral patterns are used to drive flexible energy storage and self-locking components to generate energy storage and release movements, thereby forming multiple steady-state positions (the positions where the energy is at its minimum).

[0009] In addition, the flexible energy storage and self-locking components also contain a "self-locking" flexible component that can impede the movement of the flexible components. Its normal position is the locked position.

[0010] When the joint needs to be released, it needs to be switched in position by a driver so that the cam and the flexible component can generate relative movement.

[0011] A multi-stable and self-locking rotary joint includes two articulated links, a flower-shaped cam, a flexible energy storage and self-locking component (hereinafter referred to as the flexible component), and an actuator.

[0012] The flower-shaped cam is fixedly connected to the rotation center of one of the connecting rods.

[0013] The flexible component is fixed to another link and includes a symmetrical flexible parallelogram guide mechanism arranged laterally along the link. The motion output push rod contacts the cam. When the cam moves, it absorbs and releases energy to achieve multiple stable states.

[0014] The flexible component also includes a flexible locking mechanism arranged along the axial center of the connecting rod, which has a tip that abuts against the guide mechanism and uses its own high axial stiffness to hinder its movement, thereby achieving self-locking of the mechanism.

[0015] When the joint needs to be released, the driver drives the tip of the locking mechanism to the release notch on the motion output end of the guide mechanism.

[0016] A multi-stable and self-locking rotary joint includes: a second hinge link 11, a first hinge link 5, a flower-shaped cam 9, a flexible energy storage and self-locking component, and a driver.

[0017] The second hinge link 11 and the first hinge link 5 are mentioned, with the second hinge link 11 being rotatable around the first hinge link 5; the flower-shaped cam 9 and the first hinge link 5 are located on different sides of the second hinge link 11; the flower-shaped cam 9 is used to drive the flexible energy storage and self-locking component to move axially, and it is fixed to the first hinge link 5 and rotatably set on the second hinge link 11; the outer contour of the flower-shaped cam 9 forms multiple peaks and troughs; adjacent troughs are connected by peaks;

[0018] The first hinged connecting rod 5 is fixedly installed, and a flexible energy storage and self-locking component is installed on it.

[0019] The flexible energy storage and self-locking component can form a self-locking state and an unlocking state of the flower-shaped cam 9. It includes: a transverse flexible locking mechanism 7 and an axial flexible guiding mechanism 8; along the axial direction, a flexible connection is formed between the transverse flexible locking mechanism 7 and the rigid frame 6, and along the transverse direction, a flexible connection is formed between the axial flexible guiding mechanism 8 and the rigid frame 6; the rigid frame 6 is set on the first hinge link 5.

[0020] The axial flexible guide mechanism 8 is located between the transverse flexible locking mechanism 7 and the flower-shaped cam 9, and abuts against the outer contour of the flower-shaped cam 9;

[0021] The lateral flexible locking mechanism 7 abuts against the end face of the axial flexible guide mechanism 8 to form a self-locking state. When it generates lateral displacement, it releases the axial constraint on the axial flexible guide mechanism 8 to form an unlocked state.

[0022] The driver is used to drive the lateral flexible locking mechanism 7 to generate lateral displacement, thereby enabling the flower-shaped cam 9 to switch between a self-locking state and an unlocking state. It is set on the first hinge link 5.

[0023] Preferably, the axial flexible guide mechanism 8 includes:

[0024] The No. 2 flexible beam 8-3, the No. 2 moving platform 8-1, and the No. 2 tip 8-2 are connected in sequence;

[0025] The second moving platform 8-1 is used to drive the second tip 8-2 to move axially; a locking release groove is opened on the end face of the second moving platform 8-1 facing the transverse flexible locking mechanism 7. In the self-locking state, the center line of the locking release groove and the center line of the first tip 7-2 of the transverse flexible locking mechanism 7 are at different heights in the transverse direction.

[0026] Preferably, the lateral flexible locking mechanism 7 includes:

[0027] The No. 1 flexible beam 7-2, the No. 1 moving platform 7-1, and the No. 1 tip 7-2 are connected in sequence;

[0028] The first moving platform 7-1 is used to drive the first tip 7-2 to move laterally. It is connected to the transmission line 2-1. The transmission line passes through the hole of the rigid frame 6 and is fixedly connected to the first moving platform 7-1. The line segment between the transmission line 2-1 and the first moving platform 7-1 extends laterally so that the first moving platform 7-1 can generate lateral displacement.

[0029] Preferably, the driver comprises:

[0030] Transmission line 2-1 connects actuator 3 and moving platform 7-1. The line segment between transmission line 2-1 and moving platform 7-1 extends laterally.

[0031] Actuator 3 is used to drive the first tip 7-2 to move laterally and to make the first tip 7-2 point to the locking release groove to form an unlocked state. Actuator 3 is disposed on the first hinge link 5.

[0032] Preferably, the actuator 3 is a shape memory alloy.

[0033] Preferably, the transmission line 2-1 is any one of steel wire rope, Kevlar fiber rope or fishing line.

[0034] A method of using a multistable and self-locking rotary joint, based on the aforementioned multistable and self-locking rotary joint, includes the following steps:

[0035] The driver drives the first tip 7-2 to move laterally and position it toward the locking release slot, thus entering the unlocked state;

[0036] At this time, the transverse flexible locking mechanism 7 cannot hinder the movement of the second moving platform 8-1 on the axial flexible guide mechanism 8. When the second hinge link 11 is driven by an external force, it rotates around the first hinge link 5 and drives the flower-shaped cam 9 to start rotating.

[0037] The flower-shaped cam 9 rotates, which pushes the second tip 8-2 toward the first tip 7-2 and moves it axially.

[0038] When the flower-shaped cam 9 runs to the point where its crest abuts against the second tip 8-2, the locking release groove is engaged at the first tip 7-2.

[0039] As the flower-shaped cam 9 continues to rotate, the second tip 8-2 moves away from the first tip 7-2. At this time, the actuator removes the driving force, and the first tip 7-2 returns to its locked position, pointing to the center of the second moving platform 8-1 and contacting it to hinder its movement, thus entering the self-locking state again.

[0040] Compared with the prior art, the advantages of the present invention are:

[0041] 1. It can achieve multiple steady states of the rotating hinge (achieving precise position control without the need for a complex control system), and the torque required for steady state switching can be designed according to the cam shape.

[0042] 2. It can achieve non-energy-consuming self-locking in steady state, and the joint has a locking and releasing function.

[0043] 3. It relies on only one flexible component (flexible energy storage and self-locking component) and one rigid component (flower-shaped cam) to complete the functional operation. Attached Figure Description

[0044] Figure 1 This is a structural diagram of a multistable and self-locking rotary joint;

[0045] Figure 2 A schematic diagram showing the relative positions of the flower-shaped cam, flexible energy storage and self-locking component, actuator, and transmission device in the self-locking state;

[0046] Figure 3 A schematic diagram showing the relative positions of the flower-shaped cam, flexible energy storage and self-locking component, actuator and transmission device when switching steady-state positions in the unlocked state;

[0047] Figure 4 A 3D view of flexible energy storage and self-locking components;

[0048] Figure 5 This is a three-dimensional view of a flower-shaped cam.

[0049] Wherein, 1-pulley shaft;

[0050] 2-Transmission device, 2-1-Transmission line, 2-2-Guiding device;

[0051] 3-Actuator, 4-Mounting shaft, 5-No. 1 hinge link;

[0052] 6- Rigid frame;

[0053] 7- Lateral flexible locking mechanism, 7-1- No. 1 moving platform, 7-2- No. 1 tip, 7-3- No. 1 flexible beam;

[0054] 8-Axial flexible guide mechanism, 8-1-Moving platform No. 2, 8-2-Tip No. 2, 8-3-Flexible beam No. 2;

[0055] 9-Flower-shaped cam, 10-Drive shaft, 11-Second hinge link. Detailed Implementation

[0056] The multistable and self-locking rotary joint of the present invention and its method of use will be described in more detail below with reference to the schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0057] like Figures 1-5 A multi-stable and self-locking rotary joint includes: a second hinge link 11, a first hinge link 5, a flower-shaped cam 9, a flexible energy storage and self-locking component, and a driver.

[0058] When the second hinge link 11 and the first hinge link 5 are in an unlocked state under the action of an external torque, the second hinge link 11 can rotate around the first hinge link 5; the flower-shaped cam 9 and the first hinge link 5 are located on different sides of the second hinge link 11.

[0059] The first hinged link 5 is fixedly installed, and a flexible energy storage and self-locking component is installed on it.

[0060] The flexible energy storage and self-locking component can form the self-locking and unlocking states of the flower-shaped cam 9, and includes: a rigid frame 6, a transverse flexible locking mechanism 7 and an axial flexible guiding mechanism 8.

[0061] A rigid frame 6 is fixed to a first hinged link 5, and a hole is opened on it for the drive line 2-1 of the actuator to pass through; the drive line 2-1 is connected to the transverse flexible locking mechanism 7, and the other end is connected to the actuator 3 of the actuator.

[0062] Both the transverse flexible locking mechanism 7 and the axial flexible guiding mechanism 8 are mounted on the rigid frame 6, with the axial flexible guiding mechanism 8 located between the transverse flexible locking mechanism 7 and the flower-shaped cam 9.

[0063] The lateral flexible locking mechanism 7 releases the axial constraint on the axial flexible guide mechanism 8 to form an unlocked state when lateral displacement occurs; in the self-locking state, it abuts against the end face of the axial flexible guide mechanism 8, and includes:

[0064] The No. 1 flexible beam 7-2, the No. 1 moving platform 7-1, and the No. 1 tip 7-2 are connected in sequence;

[0065] The first moving platform 7-1 is used to drive the first tip 7-2 to move laterally. It is connected to the transmission line 2-1. The transmission line passes through the hole of the rigid frame 6 and is fixedly connected to the first moving platform 7-1. The line segment between the transmission line 2-1 and the first moving platform 7-1 extends laterally so that the first moving platform 7-1 can generate lateral displacement.

[0066] The structure involved in "the line segment between transmission line 2-1 and moving platform 7-1 extending laterally" is as follows:

[0067] The holes pre-drilled on the rigid frame 6 are located directly above the first moving platform 7-1 in the transverse direction. The rigid frame 6 has slots extending axially to accommodate the transmission line.

[0068] The first flexible beam 7-2 is used to generate deformation to allow the first platform 7-1 to generate lateral displacement. Its end away from the first moving platform 7-1 is fixed to the rigid frame 6; in the self-locking state, it extends axially (i.e., the first flexible beam 7-2 is not deformed).

[0069] When the first flexible beam 7-2 extends axially, it abuts against the end face of the second moving platform 8-2 of the axial flexible guide mechanism 8 to form a self-locking state. When the first flexible beam 7-2 deforms, it separates from the end face of the second moving platform 8-2 and points to the locking release groove on the second moving platform 8-2 to form an unlocked state.

[0070] That is, the starting point of the "unlocked state" is the separation of the end face of tip 7-2 and moving platform 8-2.

[0071] An axially flexible guide mechanism 8 abuts against the outer contour of a flower-shaped cam 9 (forming an elastically closed cam), comprising:

[0072] The No. 2 flexible beam 8-3, the No. 2 moving platform 8-1, and the No. 2 tip 8-2 are connected in sequence;

[0073] The second moving platform 8-1 is used to drive the second tip 8-2 to move axially; a locking release groove is opened on the end face of the second moving platform 8-1 facing the transverse flexible locking mechanism 7, and it is offset on the end face.

[0074] Specifically, the locking release groove is offset on the upper (or lower) side of the center of the left side of the moving platform, with a depth greater than or equal to the maximum stroke of the flower-shaped cam 9 (moving platform 8-1 of the second stage), and a width greater than or equal to the width of the tip 7-2 of the first stage.

[0075] The second flexible beam 8-3 is used to generate deformation to allow the second platform 8-1 to generate axial displacement. It connects the rigid frame 6 and the second moving platform 8-1. The end of it away from the second moving platform 8-1 is fixed to the rigid frame 6. In the self-locking state, it extends laterally. There are several second flexible beams 8-3, which are arranged in parallel and symmetrically.

[0076] The second tip 8-2 contacts the outer contour of the flower-shaped cam 9 and points towards the center of the flower-shaped cam 9. Under the elastic force of the axial flexible guide mechanism 8, the second tip 8-2 is always in contact with the outer contour surface of the flower-shaped cam. When the second tip 8-2 contacts the base circle of the cam, the second flexible beam 8-3 does not deform, that is, the second flexible beam 8-3 extends laterally.

[0077] A driver, used to drive the lateral flexible locking mechanism 7 to generate lateral displacement, thereby causing the flower-shaped cam 9 to switch between a self-locking state and an unlocking state, is disposed on the first hinge link 5 and includes:

[0078] The transmission line 2-1 is wound around the guide device 2-2; the transmission line 2-1 is made of steel wire rope, Kevlar fiber rope, fishing line or other ropes with a certain strength.

[0079] The guide device 2-2 is rotatably mounted on the pulley shaft 1 on the first hinge link 5. In other embodiments, the guide device 2-2 may also be a guide groove opened on the rigid frame 6.

[0080] Actuator 3, which drives the first tip 7-2 to undergo lateral displacement and points the first tip 7-2 toward the locking release slot to form an unlocked state, is disposed on the first hinge link 5. Specifically, actuator 3 is connected to the first hinge link 5 via mounting shaft 4.

[0081] Specifically, actuator 3 is selected as a small, lightweight electromagnetic, hydraulic, or pneumatic actuator, or an actuator based on smart materials, such as shape memory alloys or artificial muscles. In this embodiment, a shape memory alloy is used.

[0082] Among them, shape memory alloy wires or shape memory alloy springs can contract when energized / heated, generating driving displacement. However, they generally need to be pulled by external force after the power is turned off to return to their original length.

[0083] Therefore, preferably, another shape memory alloy spring is arranged to restore the locked position.

[0084] The second hinge link 11 is connected to the flower-shaped cam 9 via the drive shaft 10. The drive shaft 10 passes through the second hinge link 11 and is rotatably connected to the first hinge link 5.

[0085] Specifically, the drive shaft 10 is keyed to the flower-shaped cam 9, and the drive shaft 10 is fixed to the second hinged connecting rod 11.

[0086] The flower-shaped cam 9 is a follower. In the unlocked state, it can rotate under the drive of the second hinge link 11. Its outer contour has multiple up and down fluctuations, forming multiple peaks and troughs.

[0087] Flower-shaped cam 9 is used to drive flexible energy storage and self-locking components to generate energy storage and release motion, thereby forming multiple steady-state positions (the positions where the energy is at its minimum).

[0088] In the self-locking state, the axial flexible guide mechanism 8 abuts against the trough on the flower-shaped cam 9.

[0089] In the unlocked state, the flower-shaped cam 9 can rotate, and during the rotation, its contour is always in contact with the tip of the axial flexible guide mechanism 8 (i.e., the cam is an elastic force closed cam).

[0090] The rotation center of the flower-shaped cam 9 is the same as the rotation center of the first hinge link 5.

[0091] The flower-shaped cam 9 has a working curve (outer contour) that encloses between the cam base circle and the maximum outer envelope circle. This curve has multiple up-and-down fluctuations, forming multiple peaks and troughs. The bottom of the trough is tangent to the base circle.

[0092] The working principle of a multistable and self-locking rotary joint:

[0093] like Figure 2As shown, when the transverse flexible locking mechanism 7 is not deformed, its first tip 7-2 contacts the axial flexible guide mechanism 8. It can rely on its own high axial stiffness to hinder the movement of the second moving platform 8-1, thus enabling the entire rotating joint to self-lock. At this time, the second tip 8-2 abuts against the trough.

[0094] Actuator 3 generates a driving force to cause the first tip 7-2 to move laterally, positioning it towards the locking release slot. At this point, the joint loses its locking capability and enters the unlocked state. Since the first tip 7-2 only undergoes lateral displacement, it is currently located outside the locking release slot.

[0095] At this time, the transverse flexible locking mechanism 7 will not be able to hinder the movement of the second moving platform 8-1 on the axial flexible guide mechanism 8. When the second hinge link 11 of this joint is driven by an external force, the two links can rotate relative to each other. At this time, the second hinge link 11 drives the flower-shaped cam 9 to start rotating.

[0096] As the flower-shaped cam 9 rotates, due to the structural setting of its outer contour (transitioning from trough to crest), it pushes the second tip 8-2 toward the first tip 7-2 and moves axially.

[0097] like Figure 3 As shown, when the flower-shaped cam 9 runs to the point where its crest abuts against the second tip 8-2, the locking release groove is engaged at the first tip 7-2.

[0098] The flower-shaped cam 9 continues to rotate (in the same or opposite direction as before), due to the structural design of the outer contour (transition from crest to trough) and the elastic deformation already generated by the second flexible beam 8-2 (such as... Figure 3 As shown, tip 8-2 moves away from tip 7-2. At this time, the actuator removes the driving force, or another actuator drives to generate a reverse driving force. When the flower-shaped cam 9 runs to the point where its trough abuts tip 8-2, tip 7-2 returns to its locked position, pointing to the center of moving platform 8-1 and contacting it to hinder its movement, thus locking the joint. That is, at this time, the external force on hinge link 11 can no longer drive hinge link 11 to rotate around hinge link 1.

[0099] As described above, when the flower-shaped cam 9 rotates, it drives the second tip 8-2 to perform axial reciprocating motion. Through the second flexible beam 8-2 of the axial flexible guide mechanism 8, energy is stored and released, thereby achieving adjustment of the multi-steady-state position (the position where the energy minimum value is located, i.e., the trough). Furthermore, in the steady-state position, the joint can achieve non-energy-consuming self-locking.

[0100] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A multi-stable and self-locking rotary joint, characterized in that, include: Second hinge link (11), first hinge link (5), flower-shaped cam (9), flexible energy storage and self-locking component, driver; The second hinge link (11) and the first hinge link (5) are connected, with the second hinge link (11) rotating around the first hinge link (5); the flower-shaped cam (9) and the first hinge link (5) are located on different sides of the second hinge link (11); the flower-shaped cam (9) is used to drive the flexible energy storage and self-locking component to move axially, and the flexible energy storage and self-locking component is fixed to the first hinge link (5); the outer contour of the flower-shaped cam (9) forms multiple peaks and valleys; adjacent valleys are connected by peaks; The first hinged connecting rod (5) is fixedly installed, and a flexible energy storage and self-locking component is installed on it; The flexible energy storage and self-locking component can form a self-locking state and an unlocking state of the flower-shaped cam (9), which includes: a transverse flexible locking mechanism (7) and an axial flexible guiding mechanism (8). Along the axial direction, a flexible connection is formed between the transverse flexible locking mechanism (7) and the rigid frame (6), and along the transverse direction, a flexible connection is formed between the axial flexible guiding mechanism (8) and the rigid frame (6); the rigid frame (6) is set on the first hinge link (5). The axial flexible guide mechanism (8) is located between the transverse flexible locking mechanism (7) and the flower-shaped cam (9), and abuts against the outer contour of the flower-shaped cam (9); The lateral flexible locking mechanism (7) abuts against the end face of the axial flexible guide mechanism (8) to form a self-locking state. When it generates lateral displacement, it releases the axial constraint on the axial flexible guide mechanism (8) to form an unlocked state. The driver is used to drive the lateral flexible locking mechanism (7) to generate lateral displacement, thereby enabling the flower-shaped cam (9) to switch between a self-locking state and an unlocking state, and is set on the first hinge link (5).

2. The multistable and self-locking rotary joint according to claim 1, characterized in that, The axial flexible guide mechanism (8) includes: The No. 2 flexible beam (8-3), the No. 2 moving platform (8-1), and the No. 2 tip (8-2) are connected in sequence; The second moving platform (8-1) is used to drive the second tip (8-2) to move axially; the second moving platform (8-1) has a locking release groove on its end face facing the transverse flexible locking mechanism (7). In the self-locking state, the center line of the locking release groove and the center line of the first tip (7-2) of the transverse flexible locking mechanism (7) are at different heights in the transverse direction.

3. The multistable and self-locking rotary joint according to claim 2, characterized in that, The lateral flexible locking mechanism (7) includes: The first flexible beam (7-3), the first moving platform (7-1), and the first tip (7-2) are connected in sequence; The first moving platform (7-1) is used to drive the first tip (7-2) to move laterally. It is connected to the transmission line (2-1). The transmission line passes through the hole of the rigid frame (6) and is fixedly connected to the first moving platform (7-1). The line segment between the transmission line (2-1) and the first moving platform (7-1) extends laterally so that the first moving platform (7-1) can generate lateral displacement.

4. The multistable and self-locking rotary joint according to claim 3, characterized in that, The driver includes: The transmission line (2-1) connects the actuator (3) and the first moving platform (7-1), and the line segment between the transmission line (2-1) and the first moving platform (7-1) extends laterally; Actuator (3) is used to drive the first tip (7-2) to make a lateral displacement and to make the first tip (7-2) point to the locking release groove to form an unlocked state. Actuator (3) is set on the first hinge link (5).

5. The multistable and self-locking rotary joint according to claim 4, characterized in that, The actuator (3) is a shape memory alloy.

6. The multistable and self-locking rotary joint according to claim 4, characterized in that, The transmission line (2-1) is any one of steel wire rope, Kevlar fiber rope or fishing line.

7. A method of using a multistable and self-locking rotary joint, based on the multistable and self-locking rotary joint according to any one of claims 3-6, characterized in that, Includes the following steps: The driver drives the first tip (7-2) to move laterally and position it toward the locking release slot, thus entering the unlocked state; At this time, the transverse flexible locking mechanism (7) cannot hinder the movement of the second moving platform (8-1) on the axial flexible guide mechanism (8). When the second hinge link (11) is driven by an external force, it rotates around the first hinge link (5) and drives the flower-shaped cam (9) to start rotating. The flower-shaped cam (9) rotates, which pushes the second tip (8-2) toward the first tip (7-2) and moves axially; When the flower-shaped cam (9) runs to the point where its crest abuts against the second tip (8-2), the locking release groove is engaged at the first tip (7-2). As the flower-shaped cam (9) continues to rotate, the second tip (8-2) moves away from the first tip (7-2). At this time, the actuator removes the driving force, and the first tip (7-2) returns to its locked position, pointing to the center of the second moving platform (8-1) and contacting it to hinder its movement, thus entering the self-locking state again.

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