Multi-stable-state self-locking rotating joint and use method

Abstract

The invention provides a multi-stable-state self-locking rotating joint and a using method. The rotating joint comprises a second hinge connecting rod, a first hinge connecting rod, a flower-shaped cam, a flexible energy storage and self-locking component and a driver. The second hinge connecting rod can rotate around the first hinge connecting rod; the flower-shaped cam is used for driving the flexible energy storage and self-locking component to move in the axial direction, and the outer contour of the flower-shaped cam forms a plurality of wave crests and wave troughs. The adjacent wave troughs are connected through wave crests; the first hinge connecting rod is fixedly arranged, and a flexible energy storage and self-locking component is arranged on the first hinge connecting rod; the flexible energy storage and self-locking component can form a self-locking state and an unlocking state of the flower-shaped cam and comprises a transverse flexible locking mechanism and an axial flexible guide mechanism; flexible connection is formed between the flexible locking mechanism and the rigid frame in the axial direction and the transverse direction, and flexible connection is formed between the flexible guiding mechanism and the rigid frame in the transverse direction and the axial direction. The driver is used for driving the transverse flexible locking mechanism to generate transverse displacement. According to the invention, multistable positioning and self-locking can be realized at the same time, and a novel solution is provided for construction of a multistable variant / folding and unfolding structure and a multistable deformation robot.

Description

Technical Field

[0001] The present invention belongs to the field of multi-stable morphology realization and non-energy-consuming self-preserving morphology technology in the field of robots, and in particular relates to a multi-stable and self-locking rotating joint and a use method thereof. Background Art

[0002] Rotary joints are widely used in robotic systems and adaptive aerospace structures. The overall shape of the robot or deformable structure can be changed by changing the position of the hinge. However, if you want to achieve precise position control and position locking, so as to realize the load-carrying task operation of the entire system, you need to add a complex position feedback control system and a mechanical locking mechanism to the hinge. In some fields with strict design space and important requirements, the large-scale use of such rotary joints is difficult to meet the system's requirements for simplicity, reliability, design space, weight cost, etc.

[0003] Therefore, in order to solve this problem, scholars have proposed some bistable rolling joints for constructing multistable deformation systems. 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 proposed a bistable rolling joint based on modifying the geometry of the rolling hinge.

[0004] However, existing revolute joints are difficult to achieve multiple stable positions and cannot achieve self-locking of stable positions. This means that the deformable system constructed using them can achieve fewer stable states and is difficult to use under heavy load conditions. Summary of the invention

[0005] The purpose of the present invention is to provide a multi-stable and self-locking rotary joint and a method of use, which can achieve multiple stable positions, specifically a stable self-locking function and a locking release function. The technical solution adopted is as follows:

[0006] The present invention aims at the problem that hinges are difficult to achieve multiple stable positions, stable self-locking function, and the locking and releasing mechanism is complicated, and provides a novel multi-stable self-locking rotating joint based on a flexible flower-shaped cam and a flexible mechanism with energy storage and locking functions. The joint can achieve multiple stable positions, stable self-locking function, and locking and releasing function.

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

[0008] The rigid flower shape is used to drive the flexible energy storage and self-locking components to generate energy storage and energy release movements, thereby forming multiple steady-state positions (positions where energy minima are located).

[0009] In addition, there is a "self-locking" flexible component inside the flexible energy storage and self-locking component that can hinder the movement of the flexible component, and 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 produce relative movement.

[0011] A multi-stable and self-locking rotating joint comprises two articulated connecting rods, a flower-shaped cam, a flexible energy storage and self-locking component (flexible component for short), and a driver.

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

[0013] The flexible component is fixedly connected to another connecting rod, and comprises a symmetrical flexible parallelogram guide mechanism arranged laterally along the connecting rod. The motion output push rod contacts the cam, and energy absorption and release are generated when the cam moves, thereby realizing multi-stability.

[0014] The flexible component also includes a flexible locking mechanism arranged along the axial center of the connecting rod, on which a tip is pressed against the guide mechanism, and its own large axial rigidity is used to hinder its movement, thereby realizing 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 output end of the guide mechanism movement.

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

[0017] The second hinged link 11 and the first hinged link 5, the second hinged link 11 can rotate around the first hinged link 5; the flower-shaped cam 9 and the first hinged link 5 are located on different sides of the second hinged link 11; the flower-shaped cam 9 is used to drive the flexible energy storage and self-locking component to move axially, which is fixed to the first hinged link 5 and rotatably arranged on the second hinged link 11; the outer contour of the flower-shaped cam 9 forms a plurality of peaks and troughs; adjacent troughs are connected by peaks;

[0018] The first hinged connecting rod 5 is fixedly arranged, and a flexible energy storage and self-locking component is arranged 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, and includes: a transverse flexible locking mechanism 7 and an axial flexible guiding mechanism 8; a flexible connection is formed between the transverse flexible locking mechanism 7 and the rigid frame 6 in the axial direction, and a flexible connection is formed between the axial flexible guiding mechanism 8 and the rigid frame 6 in the transverse direction; the rigid frame 6 is arranged on the first hinge connecting rod 5;

[0020] The axial flexible guiding 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 transverse flexible locking mechanism 7 abuts against the end surface of the axial flexible guiding mechanism 8 to form a self-locking state, and releases the axial constraint on the axial flexible guiding mechanism 8 to form an unlocking state when the transverse flexible locking mechanism 7 generates a transverse displacement;

[0022] The driver is used to drive the transverse flexible locking mechanism 7 to generate a transverse displacement, so that the flower-shaped cam 9 switches between a self-locking state and an unlocking state, and is arranged on the first articulated connecting rod 5.

[0023] Preferably, the axially flexible guiding mechanism 8 comprises:

[0024] The second flexible beam 8-3, the second moving platform 8-1 and the second tip 8-2 are connected in sequence;

[0025] The No. 2 moving platform 8-1 is used to drive the No. 2 tip 8-2 to move axially; a locking release groove is provided on the end face of the No. 2 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 No. 1 tip 7-2 of the transverse flexible locking mechanism 7 are at different heights in the transverse direction.

[0026] Preferably, the transverse flexible locking mechanism 7 comprises:

[0027] A number one flexible beam 7-2, a number one moving platform 7-1 and the number one tip 7-2 are connected in sequence;

[0028] The moving platform No. 1 7-1 is used to drive the tip No. 1 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 moving platform No. 1 7-1. The line segment between the transmission line 2-1 and the moving platform No. 1 7-1 extends laterally to cause the moving platform No. 1 7-1 to produce a lateral displacement.

[0029] Preferably, the driver comprises:

[0030] 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 in the transverse direction;

[0031] The actuator 3 is used to drive the No. 1 tip 7 - 2 to undergo lateral displacement and to make the No. 1 tip 7 - 2 point to the locking release slot to form an unlocked state. The actuator 3 is disposed on the No. 1 hinge link 5 .

[0032] Preferably, the brake actuator 3 is made of shape memory alloy.

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

[0034] A method for using a multi-stable and self-locking rotary joint, based on the multi-stable and self-locking rotary joint, comprises the following steps:

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

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

[0037] The flower-shaped cam 9 rotates, pushing the second tip 8-2 toward the first tip 7-2 and moving along the axial direction;

[0038] When the flower-shaped cam 9 runs to the point where its wave crest abuts against the No. 2 tip 8-2, the locking release groove is locked at the No. 1 tip 7-2;

[0039] The flower-shaped cam 9 continues to rotate, and the No. 2 tip 8-2 moves in the direction away from the No. 1 tip 7-2. At this time, the actuator removes the driving force, and the No. 1 tip 7-2 will return to its locked position, pointing to the center of the No. 2 moving platform 8-1 and contacting it to hinder its movement, and enter the self-locking state again.

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

[0041] 1. It can realize multiple steady states of the rotating hinge (avoiding the use of complex control systems to achieve precise position control), and the required torque for steady state switching can be designed according to the cam shape.

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

[0043] 3. It only relies on a flexible component (flexible energy storage and self-locking component) and a rigid component (flower-shaped cam) to complete functional operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural diagram of a multi-stable and self-locking revolute joint;

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

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

[0047] Figure 4 It is a three-dimensional diagram of the flexible energy storage and self-locking component;

[0048] Figure 5 It is a three-dimensional diagram of the flower-shaped cam.

[0049] Among them, 1- pulley shaft;

[0050] 2-transmission device, 2-1-transmission line, 2-2-guide device;

[0051] 3-actuator, 4-mounting shaft, 5-hinged connecting rod No. 1;

[0052] 6- Rigid frame;

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

[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-transmission shaft, 11-No. 2 articulated connecting rod. DETAILED DESCRIPTION

[0056] The following will be described in more detail with reference to the schematic diagram of the multi-stable and self-locking rotary joint and the method of use of the present invention, wherein the preferred embodiment of the present invention is shown, and it should be understood that the present invention described herein can be modified by a person skilled in the art, while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as being widely known to a person skilled in the art, and not as a limitation of the present invention.

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

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

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

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

[0061] The rigid frame 6 is fixed to the first hinge connecting rod 5, and a hole is provided on the frame for the transmission line 2-1 of the driver to pass through; the transmission line 2-1 is connected to the transverse flexible locking mechanism 7, and the other end is connected to the actuator 3 of the driver.

[0062] The transverse flexible locking mechanism 7 and the axial flexible guiding mechanism 8 are both arranged on the rigid frame 6, and the axial flexible guiding mechanism 8 is 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 guiding mechanism 8 to form an unlocked state when the lateral displacement occurs; in the self-locking state, the lateral flexible locking mechanism 7 abuts against the end surface of the axial flexible guiding mechanism 8, and includes:

[0064] A number one flexible beam 7-2, a number one moving platform 7-1 and a number one tip 7-2 are connected in sequence;

[0065] The moving platform No. 1 7-1 is used to drive the tip No. 1 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 moving platform No. 1 7-1. The line segment between the transmission line 2-1 and the moving platform No. 1 7-1 extends laterally to cause the moving platform No. 1 7-1 to produce a lateral displacement.

[0066] Among them, the structure involved in “the line segment between the transmission line 2-1 and the first moving platform 7-1 extends in the horizontal direction” is:

[0067] The hole reserved on the rigid frame 6 is located directly above the first moving platform 7 - 1 in the horizontal direction. A groove extending in the axial direction is provided on the rigid frame 6 for placing the transmission line.

[0068] The No. 1 flexible beam 7-2 is used to generate deformation to allow the No. 1 platform 7-1 to generate lateral displacement. Its end away from the No. 1 dynamic platform 7-1 is fixed to the rigid frame 6; in the self-locking state, it extends axially (that is, the No. 1 flexible beam 7-2 is not deformed).

[0069] Tip No. 1 7-2, when flexible beam No. 1 7-2 extends axially, it abuts against the end face of movable platform No. 2 8-2 of the axial flexible guide mechanism 8 to form a self-locking state. When flexible beam No. 1 7-2 is deformed, it separates from the end face of movable platform No. 2 8-2 and points to the locking release groove on movable platform No. 2 8-2 to form an unlocking state.

[0070] That is, the starting point of the "unlocked state" is when the end surface of the No. 1 tip 7-2 is separated from the end surface of the No. 2 moving platform 8-2.

[0071] The axially flexible guiding mechanism 8, which abuts against the outer contour of the flower-shaped cam 9 (forming an elastic force closed cam), comprises:

[0072] The second flexible beam 8-3, the second moving platform 8-1 and the second tip 8-2 are connected in sequence;

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

[0074] Specifically, the locking release groove is offset to the upper side (or lower side) of the left center of the moving platform, its depth is greater than or equal to the maximum stroke of the flower-shaped cam 9 (moving platform No. 2 8-1), and its width is greater than or equal to the width of the tip No. 1 7-2.

[0075] The No. 2 flexible beam 8-3 is used to generate deformation to allow the No. 2 platform 8-1 to generate axial displacement. It connects the rigid frame 6 and the No. 2 moving platform 8-1, and its end away from the No. 2 moving platform 8-1 is fixed to the rigid frame 6; it extends laterally in the self-locking state; the number of No. 2 flexible beams 8-3 is several, and they are arranged in parallel and symmetrically.

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

[0077] The driver is used to drive the lateral flexible locking mechanism 7 to produce lateral displacement, so that the flower-shaped cam 9 switches between the self-locking state and the unlocking state. The driver is arranged on the first articulated connecting rod 5, and includes:

[0078] The transmission line 2-1 is wound around the guide device 2-2; the transmission line 2-1 is selected from steel wire ropes, Kevlar fiber ropes, fishing lines and other ropes with a certain strength.

[0079] The guide device 2-2 rotates the pulley shaft 1 disposed on the first hinge connecting rod 5. In other embodiments, the guide device 2-2 can also be a guide groove opened on the rigid frame 6.

[0080] The actuator 3 is used to drive the first tip 7-2 to move laterally and point the first tip 7-2 to the locking release slot to form an unlocked state. The actuator 3 is arranged on the first hinge connecting rod 5. Specifically, the actuator 3 is connected to the first hinge connecting rod 5 through the mounting shaft 4.

[0081] Specifically, the actuator 3 is a small, light-weight electromagnetic, hydraulic, or pneumatic actuator or an actuator based on smart materials, such as shape memory alloy or artificial muscle. In this embodiment, the actuator is a shape memory alloy.

[0082] Among them, shape memory alloy wire or shape memory alloy spring can shrink after being energized / heated to generate driving displacement. However, it usually needs to be pulled by external force after power is turned off to restore its original length.

[0083] Therefore, preferably, another memory alloy spring is arranged for restoring the locked position.

[0084] The second articulated link 11 is connected to the flower-shaped cam 9 via a transmission shaft 10 . The transmission shaft 10 passes through the second articulated link 11 and is rotationally connected to the first articulated link 5 .

[0085] Specifically, the transmission shaft 10 is key-connected with the flower-shaped cam 9 , and the transmission shaft 10 is fixed to the second hinge connecting rod 11 .

[0086] The flower-shaped cam 9 is a driven member, which can rotate under the drive of the second hinge connecting rod 11 in the unlocked state, and its outer contour has multiple up and down fluctuations, forming multiple peaks and troughs.

[0087] The flower-shaped cam 9 is used to drive the flexible energy storage and self-locking components to generate energy storage and energy release movements, thereby forming a plurality of steady-state positions (positions where energy minimum values ​​are located).

[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 its profile is always in contact with the tip of the axial flexible guide mechanism 8 during the rotation process (that is, 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 articulated connecting rod 5 .

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

[0092] Working principle of a multi-stable and self-locking revolute 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 guiding mechanism 8, and can rely on its own large axial rigidity to hinder the movement of the second moving platform 8-1, so that the rotating joint as a whole can be self-locking. At this time, the second tip 8-2 abuts against the trough.

[0094] The actuator 3 generates a driving force to drive the first tip 7-2 to move laterally and point its position to the locking release slot, at which time the joint loses the locking ability and enters the unlocking state. Since the first tip 7-2 only moves laterally, it is located outside the locking release slot at this time.

[0095] At this time, the transverse flexible locking mechanism 7 will not hinder the movement of the second movable platform 8-1 on the axial flexible guiding mechanism 8. When the second hinged connecting rod 11 of the joint is driven by external force, the two connecting rods can rotate relative to each other, and at this time, the second hinged connecting rod 11 drives the flower-shaped cam 9 to start rotating.

[0096] The flower-shaped cam 9 rotates, and due to the structural setting of the outer contour (transition from wave trough to wave peak), it pushes the second tip 8-2 toward the first tip 7-2 and moves along the axial direction.

[0097] like Figure 3 As shown, when the flower-shaped cam 9 runs to the point where its wave crest abuts against the No. 2 tip 8-2, the locking release groove is clamped on the No. 1 tip 7-2.

[0098] The flower-shaped cam 9 continues to rotate (the direction of rotation is the same as or opposite to the original direction of rotation). Due to the structural setting of the outer contour (transition from the crest to the trough) and the elastic deformation of the second flexible beam 8-2 (such as Figure 3 As shown), the No. 2 tip 8-2 moves in the direction away from the No. 1 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 against the No. 2 tip 8-2, the No. 1 tip 7-2 returns to its locked position, pointing to the center of the No. 2 moving platform 8-1 and contacting it to hinder its movement, causing the joint to self-lock. That is, at this time, the external force on the No. 2 articulated link 11 cannot continue to drive the No. 2 articulated link 11 to rotate around the No. 1 articulated link.

[0099] From the above, when the flower-shaped cam 9 rotates, the flower-shaped cam 9 will drive the second tip 8-2 to perform axial reciprocating motion, and the second flexible beam 8-2 of the axial flexible guide mechanism 8 can store and release energy, thereby realizing the adjustment of multiple stable positions (the position where the energy minimum is located, i.e., the trough). Moreover, in the stable position, the non-energy-consuming self-locking of the joint can be realized.

[0100] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A multi-stable and self-locking revolute joint, characterized in that: include: A second articulated connecting rod (11), a first articulated connecting rod (5), a flower-shaped cam (9), a flexible energy storage and self-locking component, and a driver; The second hinged link (11) and the first hinged link (5), the second hinged link (11) can rotate around the first hinged link (5); the flower-shaped cam (9) and the first hinged link (5) are located on different sides of the second hinged link (11); the flower-shaped cam (9) is used to drive the flexible energy storage and self-locking component to move along the axial direction, and is fixed to the first hinged link (5) and rotatably arranged on the second hinged link (11); the outer contour of the flower-shaped cam (9) forms a plurality of wave crests and wave troughs; adjacent wave troughs are connected by wave crests; The first hinged connecting rod (5) is fixedly arranged, and a flexible energy storage and self-locking component is arranged 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), and comprises: a transverse flexible locking mechanism (7) and an axial flexible guiding mechanism (8); A flexible connection is formed between the lateral flexible locking mechanism (7) and the rigid frame (6) in the axial direction, and a flexible connection is formed between the axial flexible guiding mechanism (8) and the rigid frame (6) in the lateral direction; the rigid frame (6) is arranged on the first hinge connecting rod (5); The axially flexible guiding mechanism (8) is located between the transversely flexible locking mechanism (7) and the flower-shaped cam (9), and abuts against the outer contour of the flower-shaped cam (9); The transverse flexible locking mechanism (7) abuts against the end surface of the axial flexible guiding mechanism (8) to form a self-locking state, and releases the axial constraint on the axial flexible guiding mechanism (8) to form an unlocking state when the transverse flexible locking mechanism (7) produces a transverse displacement; The driver is used to drive the transverse flexible locking mechanism (7) to generate a transverse displacement, thereby switching the flower-shaped cam (9) between a self-locking state and an unlocking state, and is arranged on the first hinge connecting rod (5).

2. The multi-stable and self-locking revolute joint according to claim 1, characterized in that: The axially flexible guiding mechanism (8) comprises: A second flexible beam (8-3), a second moving platform (8-1) and a second tip (8-2) are connected in sequence; The second movable platform (8-1) is used to drive the second tip (8-2) to move axially; a locking release groove is provided on the end surface of the second movable 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.

3. The multi-stable and self-locking revolute joint according to claim 2, characterized in that: The transverse flexible locking mechanism (7) comprises: A No. 1 flexible beam (7-2), a No. 1 moving platform (7-1) and the No. 1 tip (7-2) are connected in sequence; The first moving platform (7-1) is used to drive the first tip (7-2) to move in a lateral direction, and is connected to a transmission line (2-1). The transmission line passes through a hole in 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 in a lateral direction so that the first moving platform (7-1) generates a lateral displacement.

4. The multi-stable and self-locking revolute joint according to claim 3, characterized in that: The driver comprises: A transmission line (2-1) connects the actuator (3) and the first moving platform (7-1), and a line segment between the transmission line (2-1) and the first moving platform (7-1) extends in a transverse direction; The actuator (3) is used to drive the No. 1 tip (7-2) to undergo lateral displacement and to make the No. 1 tip (7-2) point to the locking release slot to form an unlocked state. The actuator (3) is arranged on the No. 1 hinge connecting rod (5).

5. The multi-stable and self-locking revolute joint according to claim 4, characterized in that: The brake actuator (3) is a shape memory alloy.

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

7. A method for using a multi-stable and self-locking rotary joint, based on the multi-stable and self-locking rotary joint according to claims 3-6, characterized in that: The following steps are involved: The driver drives the first tip (7-2) to move laterally and point it to the locking release slot, thus entering an unlocking state; At this time, the transverse flexible locking mechanism (7) cannot hinder the movement of the second movable platform (8-1) on the axial flexible guiding mechanism (8). When the second hinged connecting rod (11) is driven by an external force, it rotates around the first hinged connecting rod (5) and drives the flower-shaped cam (9) to start rotating. The flower-shaped cam (9) rotates, pushing the second tip (8-2) toward the first tip (7-2) and moving along the axial direction; When the flower-shaped cam (9) runs until its wave crest abuts against the No. 2 tip (8-2), the locking release groove is clamped on the No. 1 tip (7-2); The flower-shaped cam (9) continues to rotate, and the second tip (8-2) moves in a direction 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, and enters the self-locking state again.

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