Preparation method of multi-stage helical structure polymer fiber artificial muscle

Abstract

The invention discloses a preparation method of polymer fiber artificial muscle with a multistage spiral structure, and relates to the technical field of polymer fiber artificial muscle. The method comprises the following steps: firstly, applying a torque combined load to polymer fibers for twisting, stopping twisting when the polymer fibers are self-wound to form a stable primary spiral structure, and then winding an obtained primary spiral structure polymer fiber matrix on a rigid mandrel to form a secondary spiral structure; or winding the polymer fiber matrix with the first-stage spiral structure on a spring mandrel to form a third-stage spiral structure, so as to obtain a polymer fiber material with a third-stage spiral structure; and annealing and training to obtain the multistage helical structure polymer fiber artificial muscle. The driving performance of the artificial muscle is improved through the synergistic effect between layers of the multi-stage spiral structure, meanwhile, the characteristics that materials are easy to obtain and the preparation process is simple are achieved, and further development of twisted and rolled artificial muscle research and application is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of polymer fiber artificial muscles, in particular to a method for preparing a multi-level helical structure polymer fiber artificial muscle. Background Art

[0002] As the core actuator in the field of soft robots, artificial muscles can achieve reversible contraction, bending and rotational deformation under multi-physical field excitation, providing soft robots with high degrees of freedom, low noise and lightweight driving force. This unique performance makes it one of the important research directions in the field of smart materials. However, although traditional artificial muscle technologies such as shape memory alloys, dielectric elastomers, pneumatic artificial muscles and ionic polymers have made significant progress, there are still many limitations that restrict their further development in practical applications. Taking shape memory alloys as an example, although they have high driving force and energy density, their stroke is small and the hysteresis effect is obvious, which makes it difficult to meet the needs of efficient driving; dielectric elastomers require high voltage drive and rely on pre-stretched fixed structures to maintain stability, which not only increases the complexity of the system, but also weakens its inherent flexibility advantage. In contrast, although pneumatic artificial muscles can provide a large driving force, their dependence on external air sources makes the entire system bulky and poorly portable. In addition, although ionic polymers can achieve rapid response and fine control, their sensitivity to humidity environments and low load capacity limit their application scenarios.

[0003] Among these traditional artificial muscle technologies, conductive polymer artificial muscles stand out due to their low driving voltage and excellent conductive properties, showing broad application prospects in the fields of medical health monitoring, smart fabrics and human-computer interaction. However, the research on conductive polymer artificial muscles is still in its initial stage, and its structural design is relatively simple, resulting in limited driving ability and unable to fully meet high-performance requirements. Therefore, the development of artificial muscles with new structures to improve their driving performance has become one of the key issues that need to be solved urgently. This breakthrough will not only promote the practical application of artificial muscle technology, but also lay a solid foundation for the diversified application of soft robots, thereby promoting the deep integration and development of intelligent materials and robotics technology.

[0004] In summary, the research and development of artificial muscles is not only an important topic in the field of soft robotics, but also an indispensable part of realizing the future intelligent society. Through innovative material design and optimized structural process, it is expected to overcome the bottleneck of existing technology and promote artificial muscle technology to a more mature and widely used stage. However, despite this, there are few technical studies on conductive polymer artificial muscles, and there are problems of complex preparation process and high cost. In order to improve the performance of the actuator, it is usually necessary to rely on chemical reagents to modify or treat the materials, which not only increases the difficulty of the process, but also limits the possibility of large-scale application. At present, there is no report on the research on improving the driving performance of polymer fiber artificial muscles by changing the physical structure. Based on the above technical background, the present invention provides a polymer fiber artificial muscle based on a multi-level spiral structure, which will provide a new idea for the development of technology in the field of soft robotics, and is expected to break through the bottleneck of existing technology and promote the development of artificial muscle technology in a more efficient and low-cost direction. Summary of the invention

[0005] The present invention aims to propose a method for preparing an artificial muscle of a multi-level helical structure polymer fiber, so as to effectively solve the problems of complex preparation and high cost in the prior art. The present invention successfully constructs an artificial muscle with a multi-level helical structure by adopting a unique process of twisting first and then winding. This method not only has simple and easy material selection, but also a simple and efficient preparation process, which significantly reduces the difficulty and cost of production. In addition, the prepared artificial muscle exhibits excellent driving performance and mechanical properties, which opens up a new path for the research and practical application of twisted artificial muscles, and is expected to promote this field to a deeper level.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a method for preparing a multi-level helical polymer fiber artificial muscle, comprising the following steps:

[0008] Step 1: Preparation of primary helical polymer fiber matrix

[0009] One end of the polymer fiber is connected to a motor, and a load is hung on the other end and a lightweight anti-untwisting device is fixed. The motor applies a torque composite load to the polymer fiber, and the twisting is stopped when the polymer fiber is completely self-wound to form a stable primary helical structure, thereby obtaining a polymer fiber matrix with a primary helical structure;

[0010] or,

[0011] Applying a torque composite load to the polymer fiber to twist it, stopping the twisting before the polymer fiber self-winds, and then winding it on a rigid core shaft to form a primary helical structure, thereby obtaining a primary helical structure polymer fiber material;

[0012] Step 2: Formation of secondary or tertiary helical structure

[0013] Formation of secondary helical structure:

[0014] The primary helical structure polymer fiber matrix is ​​uniformly wound on the surface of a rigid core shaft by a winding machine to form a secondary helical structure, and the coil spacing is always kept constant during the winding process to obtain a secondary helical structure polymer fiber material;

[0015] Or, forming a tertiary helical structure:

[0016] The spring mandrel is stretched into a straight line for easy winding, and then the primary helical structure polymer fiber matrix is ​​evenly wound on the stretched spring mandrel by a winding machine to form a secondary helical structure (the number of winding turns is at least 2), and then the spring mandrel is retracted (retraction rate ≥ 70%) to obtain a tertiary helical structure polymer fiber material;

[0017] Alternatively, the primary helical structure polymer fiber matrix is ​​wound on a rigid core shaft to form a secondary helical structure, thereby obtaining a secondary helical structure polymer fiber material; the secondary helical structure polymer fiber material is again wound on a rigid core shaft to form a tertiary helical structure, thereby obtaining a tertiary helical structure polymer fiber material.

[0018] Step 3: Annealing and post-processing

[0019] a. placing the secondary helical structure polymer fiber material or the tertiary helical structure polymer fiber material obtained after winding in a vacuum oven and performing annealing treatment at a constant temperature to eliminate residual stress.

[0020] The annealing temperature range is preferably 70-95% of the melting point of the polymer fiber material, and the annealing time is preferably 60-150 min, which can be calculated based on the annealing temperature and the time-temperature equivalence principle.

[0021] b. After annealing, the secondary helical structure polymer fiber material or the tertiary helical structure polymer fiber material is removed from the mandrel and subjected to electrothermal cycle training.

[0022] c. The secondary helical structure polymer fiber material or the tertiary helical structure polymer fiber material obtained in step b is allowed to stand for 12 hours to prepare a multi-level helical structure polymer fiber artificial muscle with a stable initial pitch, namely, a secondary helical structure polymer fiber artificial muscle or a tertiary helical structure polymer fiber artificial muscle.

[0023] As a further preferred embodiment of the present invention, the temperature of the electrothermal cycle training is 80-220° C.; more preferably, the number of cycles of the electrothermal cycle training is ≥5 times; and even more preferably, 5 times ≤ the number of cycles ≤30 times.

[0024] As a further preferred embodiment of the present invention, the polymer fiber can be a single-strand silver-plated nylon 66 sewing thread.

[0025] The present invention provides a method for preparing an artificial muscle with a multi-level helical structure mainly composed of polymer fibers. The prepared multi-level helical structure leads to significantly improved driving performance and load capacity of the artificial muscle.

[0026] The two methods of forming the triple helical structure polymer fiber material of the present invention have equivalent technical effects, which will not be described in detail here.

[0027] The present invention improves the high driving performance of polymer fibers based on the following mechanism:

[0028] 1. Deformation superposition mechanism: The multi-level spiral structure is composed of multiple spiral levels, and the spirals of each level will produce independent deformation during the driving process. Due to the interaction and superposition effect between these spiral structures, when the spiral fibers of different levels are deformed at the same time, their deformations will be superimposed step by step, thereby greatly increasing the overall deformation. For example, based on the deformation of the first-level spiral, the second and third-level spirals are further deformed, and these deformations are cumulative, allowing the artificial muscle to achieve a larger overall deformation in a smaller space.

[0029] 2. Stress dispersion mechanism: The multi-level spiral transmits and disperses the external load to different spiral levels through the hierarchical nested geometric design. This hierarchical load-bearing method effectively avoids the problem of local stress concentration in the single spiral structure and significantly reduces the strain peak under high load. For example, the secondary spiral structure can disperse the stress to the spiral interface of the two levels under load, delaying the yield or fracture of the material, thereby improving the overall load capacity.

[0030] 3. Enhanced structural elasticity: Multi-level helices achieve greater deformation capacity through elastic coupling between levels without relying on high material elasticity. The deformation of a single helix is ​​limited by the geometric constraints of a single level, while multi-level helices can add deformation through the cooperative deformation of secondary helices (such as untwisting and unfolding).

[0031] 4. Influence of initial pitch: The hierarchical design of the multi-stage helix allows for more flexible regulation of the initial pitch. The pitch of a single helix is ​​limited by the mandrel size and annealing process, while the multi-stage helix can introduce additional pitch freedom through secondary winding. For example, through the synergy of the mandrel and self-winding, the initial pitch of the secondary helix structure can be significantly improved, thereby achieving an actuation stroke close to the theoretical limit when unloaded and maintaining a high stroke under load.

[0032] 5. Improved energy density and efficiency: The compact structure of the multi-level spiral improves the energy storage and release efficiency per unit volume. The synergistic deformation between the levels reduces energy loss (such as frictional heat and plastic deformation), and at the same time efficiently converts input energy (such as electric heat and temperature difference) into mechanical work through the geometric amplification effect.

[0033] The present invention discloses the following technical effects:

[0034] The preparation process of the multi-stage helical structure polymer fiber artificial muscle of the present invention is simple and does not require complicated instruments and equipment. The prepared artificial muscle has a stable structure and can be driven directly in the air, which helps to promote the further development of artificial muscle research and application and has broad application prospects in the fields of medicine, intelligent fabrics and soft robots.

[0035] The present invention increases the driving performance of artificial muscles through the synergistic effect between the levels of the multi-level spiral structure. It has material universality and can be applied to a variety of polymer fiber materials to meet different production needs. At the same time, it has the characteristics of easy availability of materials and simple preparation process. The prepared artificial muscles have good driving performance and mechanical properties, which will help promote the further development of research and application of twisted artificial muscles. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 This is a schematic diagram of the preparation process of the primary helical structure polymer fiber artificial muscle prepared in Example 1 of the present invention;

[0038] Figure 2 The schematic diagram (a) and the actual picture (b) of the primary helical structure polymer fiber artificial muscle prepared in Example 1 of the present invention;

[0039] Figure 3 This is a schematic diagram of the preparation process of the secondary helical structure polymer fiber artificial muscle prepared in Example 2 of the present invention;

[0040] Figure 4 The schematic diagram (a) and the actual picture (b) of the artificial muscle structure of the polymer fiber with a secondary helical structure prepared in Example 2 of the present invention;

[0041] Figure 5 This is a schematic diagram of the preparation process of the triple helical polymer fiber artificial muscle prepared in Example 3 of the present invention;

[0042] Figure 6 Schematic diagram (a) and actual picture (b) of the triple helical polymer fiber artificial muscle prepared in Example 3 of the present invention.

[0043] Figure 7 This is a graph showing the effect of annealing temperature on the performance of artificial muscle of secondary helical structure polymer fiber in Example 2 of the present invention.

[0044] Figure 8 This is a graph showing the effect of annealing time on the performance of artificial muscle of secondary helical structure polymer fiber in Example 2 of the present invention.

[0045] Fig. 9 This is a graph showing the effect of load weight on the performance of the secondary helical structure polymer fiber artificial muscle in the preparation of the primary helical structure polymer fiber matrix in Example 2 of the present invention.

[0046] Fig.10 This is a performance comparison diagram of the secondary helical structure polymer fiber artificial muscle of Example 2 of the present invention before and after electrothermal cycling at different temperatures.

[0047] Fig.11 This is a diagram of the oven heating drive test experimental device of the present invention.

[0048] Fig.12 This is a diagram of the electrothermal circulation training device of the present invention.

[0049] Fig.13 A comparison chart of the oven heating drive test results of the artificial muscles prepared in Examples 1-3 of the present invention (the primary helical structure polymer fiber artificial muscle is marked as the primary artificial muscle; the secondary helical structure polymer fiber artificial muscle is marked as the secondary artificial muscle; the tertiary helical structure polymer fiber artificial muscle is marked as the tertiary artificial muscle);

[0050] Fig.14 This is a comparison chart of the load limit results of the artificial muscles prepared in Examples 1-3 of the present invention (the primary helical structure polymer fiber artificial muscle is marked as the primary artificial muscle; the secondary helical structure polymer fiber artificial muscle is marked as the secondary artificial muscle; the tertiary helical structure polymer fiber artificial muscle is marked as the tertiary artificial muscle). DETAILED DESCRIPTION

[0051] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0052] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0053] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0054] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0055] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0056] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in the art and are not the focus of the present invention.

[0057] The polymer fiber used in the following examples of the present invention is a single-strand silver-plated nylon 66 sewing thread purchased from Shieldex, Germany, and has a melting point of 264° C. In the present invention, the room temperature referred to is 25° C.

[0058] Example 1

[0059] Figure 1 This is a schematic diagram of the preparation process of the primary helical structure polymer fiber artificial muscle according to Example 1 of the present invention.

[0060] (1) Preparation of primary helical structure polymer fiber materials

[0061] One end of the polymer fiber is connected to the motor, and a load (load weight is 200g) is hung on the other end. At the same time, a slider (lightweight anti-untwisting device) weighing 10g is hung to prevent untwisting during the winding process of the polymer fiber, and the polymer fiber is twisted by the motor. When twisted to a certain extent, the polymer fiber will begin to self-wind and form a tiny spiral structure. The state when self-winding does not occur is regarded as the end of twisting. The twisted polymer fiber is taken off and wound using a winder. One end is fixed to one side of the mandrel (the mandrel is a smooth metal wire) to obtain a primary spiral structure polymer fiber material.

[0062] (2) Annealing and post-treatment

[0063] a. Fix the two ends of the primary helical polymer fiber material and place it in a constant temperature box for annealing at a temperature of 220°C for 150 min;

[0064] b. The annealed primary helical structure polymer fiber material is electrically heated to 220°C, and then naturally cooled to room temperature, and the process is repeated 5 times, that is, 5 electric heating cycle trainings are completed;

[0065] c. The primary helical structure polymer fiber material obtained in step b was allowed to stand at room temperature for 12 hours to obtain a primary helical structure polymer fiber artificial muscle.

[0066] Figure 2 Schematic diagram (a) and actual picture (b) of the primary helical structure polymer fiber artificial muscle prepared in Example 1 of the present invention.

[0067] Example 2

[0068] Figure 3 This is a schematic diagram of the preparation process of the secondary helical structure polymer fiber artificial muscle of Example 2 of the present invention.

[0069] (1) Preparation of primary helical structure polymer fiber matrix

[0070] One end of the polymer fiber is connected to the motor, and a load (load weight of 200g) is hung on the other end. At the same time, a slider (lightweight anti-untwisting device) weighing 10g is hung to prevent the polymer fiber from untwisting during the winding process. The motor is used to twist the polymer fiber. When twisted to a certain extent, the polymer fiber begins to self-wind and form a tiny spiral structure. When the entire length range of the polymer fiber is self-winding, the process ends and a primary spiral structure polymer fiber matrix is ​​obtained.

[0071] (2) Formation of secondary helical structure

[0072] The primary helical polymer fiber matrix is ​​removed and wound using a winding machine, with one end fixed to one side of a core shaft, and the core shaft is made of smooth metal wire. During the winding process, a load of the same weight as before is hung on the other end of the fiber, and there is no gap between the coils during winding, thus obtaining a secondary helical polymer fiber material.

[0073] (3) Annealing and post-treatment

[0074] a. Fix the two ends of the secondary helical structure polymer fiber material and place it in a constant temperature box for annealing at a temperature of 220°C for 80 min;

[0075] b. The annealed secondary helical structure polymer fiber material is removed from the mandrel, electrically heated to 100°C, and then naturally cooled to room temperature. The process is repeated 5 times, that is, 5 electric heating cycle trainings are completed;

[0076] c. The secondary helical structure polymer fiber material obtained in step b was allowed to stand at room temperature for 12 hours to prepare a secondary helical structure polymer fiber artificial muscle.

[0077] Figure 4 The schematic diagram (a) and the actual picture (b) of the artificial muscle of the polymer fiber with a secondary helical structure prepared in Example 2 of the present invention are shown.

[0078] Example 3

[0079] Figure 5 This is a schematic diagram of the preparation process of the triple helical polymer fiber artificial muscle of Example 3 of the present invention.

[0080] (1) Preparation of primary helical structure polymer fiber matrix

[0081] One end of the polymer fiber is connected to the motor, and a load (load weight of 200g) is hung on the other end. At the same time, a slider (lightweight anti-untwisting device) weighing 10g is hung to prevent the polymer fiber from untwisting during the winding process. The motor is used to twist the polymer fiber. When twisted to a certain extent, the polymer fiber begins to self-wind and form a tiny spiral structure. When the entire length range of the polymer fiber is self-winding, the process ends, and a primary spiral structure polymer fiber matrix is ​​prepared.

[0082] (2) Formation of a triple helical structure

[0083] The mandrel uses a spring mandrel. First, the spring mandrel is straightened by horizontal stretching by a motor. Then the primary helical structure polymer fiber matrix is ​​removed, one end is fixed to one side of the mandrel, and a winding machine is used to wind it on the straightened spring mandrel. After the winding is completed and the spring is released, the spring retracts 75%. During the winding process, a load of the same weight as before is hung on the other end of the fiber. There is no gap between the coils during winding, and a three-level helical structure polymer fiber material is obtained.

[0084] (3) Annealing and post-treatment

[0085] a. Fix the two ends of the three-level helical structure polymer fiber material and place it in a constant temperature box for annealing. The annealing temperature is 220°C and the annealing time is 80 min;

[0086] b. The annealed three-level helical structure polymer fiber material is removed from the mandrel, electrically heated to 120°C, and then naturally cooled to room temperature. The process is repeated 5 times, that is, 5 electric heating cycle trainings are completed;

[0087] c. The triple helical structure polymer fiber material treated in step b was allowed to stand at room temperature for 12 hours to prepare a triple helical structure polymer fiber artificial muscle.

[0088] Figure 6 The schematic diagram (a) and the actual picture (b) of the artificial muscle of triple helical polymer fiber prepared in Example 3 of the present invention are shown.

[0089] Figure 7 This is a graph showing the effect of annealing temperature on the performance of artificial muscle of secondary helical structure polymer fiber in Example 2 of the present invention.

[0090] Figure 8 This is a graph showing the effect of annealing time on the performance of artificial muscle of secondary helical structure polymer fiber in Example 2 of the present invention.

[0091] Fig. 9 This is a graph showing the effect of load weight on the performance of the secondary helical structure polymer fiber artificial muscle in the preparation of the primary helical structure polymer fiber matrix in Example 2 of the present invention.

[0092] Fig.10 This is a performance comparison diagram of the secondary helical structure polymer fiber artificial muscle of Example 2 before and after electrothermal cycling at different temperatures.

[0093] Fig.11This is a diagram of the experimental setup for the oven heating drive test. Oven heating drive test process: In order to measure the tensile strain caused by oven heating, the artificial muscle with a weight hanging at the end is placed in a high temperature test chamber (DHG-9425A, Shanghai Yiheng Scientific Instrument Co., Ltd.), and a thermocouple thermometer (UT320XD, UNIT) is used to monitor the ambient temperature near the artificial muscle. A ruler is used for displacement measurement, and a pointer is used to indicate the ruler position, while preventing the artificial muscle from untwisting. The experimental temperature range is 40-160°C, and 10°C is used as the heating step. At each target temperature, wait for 1 minute to ensure that the temperature in the oven reaches a steady state. Subsequently, the contraction displacement of the artificial muscle is recorded, and the value of the tensile strain is obtained by dividing the contraction displacement variable by the initial length of the artificial muscle.

[0094] Fig.12 The figure shows the experimental device of electrothermal cycle training. Electrothermal cycle training process: hang the artificial muscle with a lightweight anti-untwisting device and weights at the end vertically on the test bench, use a laser displacement sensor (PDL-030-485) to monitor the displacement of the lightweight anti-untwisting device, and record the signal through a computer. Use an infrared camera to monitor and record the temperature of the artificial muscle. When the temperature of the artificial muscle reaches the target temperature, stop the power supply, and wait for it to cool naturally to room temperature for one cycle.

[0095] Load limit test process: The experimental setting is the same as the oven heating drive test. The weight of the end weight is changed to repeat the experiment. When the weight of the weight reaches the load limit, the artificial muscle will untwist during the heating process and cannot produce normal contraction. The load weight at this time is the load limit of this type of artificial muscle.

[0096] Fig.13 A comparison chart of the oven heating drive test results of the artificial muscles prepared in Examples 1-3 (the primary helical structure polymer fiber artificial muscle is marked as the primary artificial muscle; the secondary helical structure polymer fiber artificial muscle is marked as the secondary artificial muscle; the tertiary helical structure polymer fiber artificial muscle is marked as the tertiary artificial muscle); Fig.13 It can be seen that with the increase of the number of spirals, the strain of the artificial muscle under the same load and temperature is also increased.

[0097] Fig.14 The load limit results comparison diagram of the artificial muscles prepared in Examples 1-3 (the primary helical structure polymer fiber artificial muscle is marked as the primary artificial muscle; the secondary helical structure polymer fiber artificial muscle is marked as the secondary artificial muscle; the tertiary helical structure polymer fiber artificial muscle is marked as the tertiary artificial muscle). Fig.14 It can be seen that with the increase of the number of spiral series of artificial muscles, the ultimate load is also improved and the load capacity becomes stronger.

[0098] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a multi-level helical polymer fiber artificial muscle, characterized in that: The following steps are involved: Step 1: Preparation of primary helical polymer fiber matrix Applying a torque composite load to the polymer fiber to twist it, and stopping the twisting when the polymer fiber is completely self-wound to form a stable primary helical structure, thereby obtaining the primary helical structure polymer fiber matrix; or, Applying a torque composite load to the polymer fiber to twist it, stopping the twisting before the polymer fiber self-winds, and then winding it on a rigid core shaft to form a primary helical structure, thereby obtaining a primary helical structure polymer fiber material; Step 2: Formation of secondary or tertiary helical structures Winding the primary helical structure polymer fiber matrix on a rigid core shaft to form a secondary helical structure, thereby obtaining a secondary helical structure polymer fiber material; or, The spring mandrel is stretched into a straight line for easy winding, and then the primary helical structure polymer fiber matrix is ​​wound on the stretched spring mandrel to form a secondary helical structure, and then the spring mandrel is retracted to form a tertiary helical structure to obtain a tertiary helical structure polymer fiber material; or, Winding the primary helical structure polymer fiber matrix on a rigid core shaft to form a secondary helical structure, thereby obtaining a secondary helical structure polymer fiber material; Winding the secondary helical structure polymer fiber material again on a rigid core shaft to form a tertiary helical structure, thereby obtaining a tertiary helical structure polymer fiber material; Step 3: Annealing and post-processing The secondary helical structure polymer fiber material or the tertiary helical structure polymer fiber material is annealed and then subjected to electrothermal cycle training to obtain a secondary helical structure polymer fiber artificial muscle or a tertiary helical structure polymer fiber artificial muscle, thereby completing the preparation of the multi-level helical structure polymer fiber artificial muscle.

2. The method for preparing multi-stage helical polymer fiber artificial muscle according to claim 1, characterized in that: The temperature of the annealing treatment is 70-95% of the melting point of the polymer fiber; the time of the annealing treatment is 60-150 minutes.

3. The method for preparing multi-stage helical polymer fiber artificial muscle according to claim 1, characterized in that: The electrothermal circuit training also includes a resting step.

4. The method for preparing a multi-stage helical polymer fiber artificial muscle according to claim 1, characterized in that: The temperature of the electrothermal cycle training is 80-220°C.

5. The method for preparing multi-stage helical polymer fiber artificial muscle according to claim 4, characterized in that: The number of cycles of the electrothermal cycle training is ≥5 times and ≤30 times.

6. An artificial muscle of a multi-stage helical polymer fiber prepared by the method for preparing an artificial muscle of a multi-stage helical polymer fiber as claimed in any one of claims 1 to 5.

7. The multi-stage helical polymer fiber artificial muscle according to claim 6, characterized in that: It includes a secondary helical structure polymer fiber artificial muscle or a tertiary helical structure polymer fiber artificial muscle.

8. Application of the multi-level helical structure polymer fiber artificial muscle as claimed in claim 7 in the field of soft robots.

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