Shape memory alloy and soft composite structure hybrid driver, hand exoskeleton and method

Abstract

The invention relates to a shape memory alloy and soft composite structure hybrid driver, a hand exoskeleton and a method. The hybrid driver comprises a flexible driving unit and an SMA spring unit, and the flexible driving unit comprises a silica gel air bag piece, an elastic air guide base and non-woven fabric; the silica gel air bag pieces are fixed to the elastic air guide base, the silica gel air bag pieces are parallel to one another and distributed at equal intervals, air cavities are formed in the silica gel air bag pieces, an air guide channel is formed in the elastic air guide base, and the non-woven fabric is fixed to the side, away from the silica gel air bag pieces, of the elastic air guide base. A spring silica gel fixing seat is arranged on the side, away from the silica gel air bag pieces, of the elastic air guide base, the SMA spring unit is fixed to the spring silica gel fixing seat, and the axial direction of the spring silica gel fixing seat is parallel to the distribution direction of the silica gel air bag pieces. Compared with the prior art, the device has the advantages of being simple and portable in structure, large in force-to-weight ratio, rapid in response and the like.

Description

Technical Field

[0001] This invention relates to the field of rehabilitation robot technology, and in particular to a hybrid actuator of shape memory alloy and soft composite structure, a hand exoskeleton, and a method thereof. Background Technology

[0002] In recent years, flexible actuator technology has received widespread attention, especially in the field of robotics. Its lightweight, portable characteristics and flexible combination capabilities have great potential for application in complex, unstructured scenarios. Currently, commercially available rehabilitation hand exoskeletons employ various drive technologies. Rigid hand exoskeletons typically use motor drives, while flexible hand exoskeletons often use pneumatic, rope-driven, and smart material-based drive technologies.

[0003] Rigid hand exoskeletons commonly found on the market, driven by motors, generally suffer from problems such as large mass, bulky size, and poor flexibility, making them difficult to meet the rehabilitation needs of most patients and limiting their applicability in home settings. While flexible hand exoskeletons are lightweight, portable, and flexible, able to adapt to dynamic changes and complex deformation applications, their flexible structures often struggle to guarantee high motion precision, making accurate control difficult.

[0004] These types of hand exoskeletons typically employ pneumatic, rope-driven, hydraulic, or smart material-driven actuation methods. Pneumatic systems require auxiliary systems such as air pumps and air circuits, which not only increases system complexity but also significantly raises manufacturing costs. Furthermore, pneumatic systems place extremely high demands on the sealing performance of the modules. While rope-driven systems offer good flexibility, they require an additional driving force source and suffer from uneven force distribution and low force transmission efficiency. Hydraulic systems offer high torque and precise control, but the hydraulic lines and storage devices occupy a large space. Among smart materials, shape memory alloys stand out for their performance, characterized by light weight, small size, and high output force, but they suffer from low cooling efficiency.

[0005] Currently, hand exoskeletons that combine rigid and flexible modules are beginning to be used. The key feature of this type of drive system is that it combines the advantages of both rigid and flexible modules to address specific challenges. The rigid module can be controlled by a motor, providing greater output force, and through sensor detection, it can achieve more precise control. The flexible module improves compliance, giving patients a better interactive experience.

[0006] For example, the invention disclosed in CN119770306A discloses a hybrid-driven hand function rehabilitation device. The five finger bending components are linear in the non-inflated state and arc-shaped in the inflated state, bending towards the glove side. The pneumatic drive is used to control the inflation and deflation of the finger bending components. The finger components include a delay control structure and at least two connected pneumatic components. The delay control structure is connected to each pneumatic component and is used to control each pneumatic bending component to be inflated and bent sequentially from the base of the finger to the fingertip.

[0007] For example, the invention disclosed in CN115463006A discloses a flexible rehabilitation glove based on a hybrid actuator, which includes five hybrid actuators and a control box for the actuators; the hybrid actuator includes a hybrid actuator end mounting base, a flexible actuator, a TPFE water pipe, a flexible actuator front mounting base, a flexible actuator air pipe, an air pipe connector two, an SMA spring actuator, an air pipe connector one, and a cooling water pipe. The control box contains an air pump, a filter, a water pump and a water tank, a proportional valve, and a control circuit board. The filter is connected to the air pump and the electric proportional valve respectively. The control box includes an actuator control box body, a control box cover, a main switch, a button, and a voltage display.

[0008] However, the aforementioned hybrid actuators still have much room for improvement in terms of integration, lightweighting, and miniaturization, making them unsuitable for complex everyday applications. Therefore, there is a need for a hybrid actuator combining shape memory alloys and soft composite structures, a hand exoskeleton, and a method that offers a relatively large driving stroke, rapid response, and convenient structure. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the existing technology, such as the limited output torque and poor response speed of pneumatic actuators with complex systems and small volume, and to provide a hybrid actuator of shape memory alloy and soft composite structure, a hand exoskeleton and method.

[0010] The objective of this invention can be achieved through the following technical solutions:

[0011] This solution provides a hybrid actuator of shape memory alloy and soft composite structure, including a flexible drive unit and an SMA spring unit. The flexible drive unit includes a silicone airbag sheet, an elastic air-conducting base and a non-woven fabric.

[0012] The silicone airbag is fixed on the elastic air-guiding base. There are multiple silicone airbags, which are parallel to each other and evenly spaced. Each silicone airbag has an air cavity, and the elastic air-guiding base has an air-guiding channel. The non-woven fabric is fixed on the side of the elastic air-guiding base away from the silicone airbag.

[0013] The elastic air-conducting base has a spring silicone fixing seat on the side away from the silicone airbag sheet. The SMA spring unit is fixed on the spring silicone fixing seat, and the axial direction of the spring silicone fixing seat is parallel to the distribution direction of the silicone airbag sheet.

[0014] Preferably, the nonwoven fabric includes a first sub-nonwoven fabric, a second sub-nonwoven fabric, and a third sub-nonwoven fabric that are distributed at intervals in sequence, and the first sub-nonwoven fabric and the third sub-nonwoven fabric are symmetrically distributed at both ends of the elastic air-conducting base.

[0015] The first and third sub-nonwoven fabrics are sheet-like structures. The second sub-nonwoven fabric includes multiple filamentous nonwoven fabric units, which are evenly spaced and perpendicular to the SMA spring units.

[0016] Preferably, the SMA spring unit includes a first spring and a second spring, which are symmetrically mounted at both ends of the spring silicone mounting base, and are connected in series by a wire.

[0017] Preferably, there are multiple spring silicone fixing seats, and the spring silicone fixing seats are distributed at equal intervals.

[0018] Preferably, there is a gap between the SMA spring unit and the lower surface of the elastic air guide base.

[0019] Preferably, the bottom of the silicone airbag is provided with a bending sensor for detecting the bending speed of the elastic air-conducting base.

[0020] This solution also provides a hand exoskeleton, including a hybrid actuator of shape memory alloy and soft composite structure, a glove, a solenoid valve, an air pump and a power supply. There are multiple hybrid actuators. Each hybrid actuator is provided at the corresponding finger joint on the glove. Each hybrid actuator is connected to the air pump through a solenoid valve. The power supply is connected to an SMA spring unit.

[0021] Preferably, the hand exoskeleton also includes a pressure sensor, and the air pump includes an inflation pump and a deflation pump, which are respectively connected to a solenoid valve via the pressure sensor; when the air pressure in the air circuit is higher than the permissible value, the inflation pump is turned off and the deflation pump is turned on.

[0022] Preferably, the glove is provided with an insulating heat strip, and the hybrid actuator is fixed on the insulating heat strip to insulate against the high temperature generated when the SMA spring unit is working.

[0023] This solution also provides a torque verification method for a hybrid actuator, based on a hybrid actuator of shape memory alloy and soft composite structure, the method comprising the following steps:

[0024] Determine the relationship between the input pressure and the expansion angle of the square air cavity inside the silicone airbag;

[0025] Calculate the bending angle formed by the expansion of the air cavity of a single silicone airbag, and further calculate the bending angle formed by the expansion of the air cavities of all silicone airbags.

[0026] Calculate the expansion force generated by the contact of a single silicone airbag cavity;

[0027] Calculate and sum the driving torque generated by the silicone airbag on the fixed point, the torque of the input air pressure on the elastic air guide base, and the torque generated by the SMA spring on the fixed end to obtain the total torque of the driver on the fixed end. Compare the total torque with the preset torque to determine whether it meets the requirements.

[0028] The expression for the total torque of the actuator about the fixed end is:

[0029]

[0030] In the formula: Δb is the difference in width between the expanded air cavity and the initial state, a is the width of the air cavity, b is the side length of the inner square air cavity, t is the wall thickness of the axial surface of the air cavity, L is the length of the airway between adjacent air cavities, w is the width of the square airway, e is the thickness of the silicone at the top of the airway, f is the thickness of the silicone at the bottom of the airway, d is the interval between air cavities, R is the radius of the air cavity circle, r is the radius of the contact surface circle between adjacent air cavities, C1 and C2 are the parameters of the silicone constitutive model, n is the number of air cavities, G is the SMA shear modulus, N is the effective number of spring coils, d is the spring wire diameter, D is the spring diameter, λ is the initial length of the spring, and θ is the bending angle formed by the inflation of all air bladders.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) In this design, an airbag is installed at the upper end of the elastic air-conducting base to extend the upper surface, while a non-woven fabric is installed at the lower end to restrict the extension of the lower surface. This, combined with the contraction of the SMA spring unit, further increases the deformation difference between the two surfaces of the elastic air-conducting base, thereby accelerating the bending motion of the actuator, generating a greater output force, and improving the response speed of the actuator. Compared with the existing structure that only uses airbag distribution to bend the actuator, this design can improve the deformation capability of the flexible actuator while keeping the flexible actuator small in volume. This is beneficial for optimizing the volume and weight of the hand exoskeleton and promotes the structural optimization of the hand exoskeleton.

[0033] (2) This solution sets two sheet-like non-woven fabrics and a middle filament-like non-woven fabric on the lower surface of the elastic air-conducting base. The sheet-like non-woven fabrics on both sides will restrict the radial and axial stretching effect of the bottom silicone, while the filament-like non-woven fabric will restrict the radial stretching of the middle silicone at the bottom of the airbag, so that the middle silicone can stretch axially and achieve a certain length compensation for finger joint bending.

[0034] (3) In this design, the SMA spring is installed at the lower end of the elastic air-conducting base, which assists the actuator in bending after being powered on. Compared with the existing structure that mounts the shape memory alloy spring as a whole on top of the flexible unit and uses water channels to regulate the spring temperature to make the spring bend, the hybrid actuator of this application simplifies the overall structure of the actuator, reduces the weight of the hand exoskeleton, and makes it easier to carry. Moreover, each joint is equipped with an independent actuator, making the adjustment of the hand exoskeleton more flexible. Attached Figure Description

[0035] Figure 1 A schematic diagram of the hand exoskeleton provided by the present invention;

[0036] Figure 2 A schematic diagram of the structure of the hybrid driver provided by the present invention;

[0037] Figure 3 This is a schematic diagram of the nonwoven fabric arrangement provided by the present invention;

[0038] Figure 4 A schematic diagram of the bottom structure of the hybrid driver provided by the present invention;

[0039] Figure 5 This is a schematic diagram of the structure of the bending sensor provided by the present invention;

[0040] Figure 6 A schematic diagram of the internal dimensions and structure of the air cavity provided by the present invention;

[0041] Figure 7 A schematic diagram of the dimensions and structure of the airbag after inflation of the air chamber provided by the present invention;

[0042] Figure 8 This is a schematic diagram of the single-cavity motion angle provided by the present invention;

[0043] Figure 9 A schematic diagram of the dimensions and structure of the airbag in contact state provided by the present invention;

[0044] In the diagram: 1. Flexible drive unit; 2. SMA spring unit; 3. Glove; 4. Solenoid valve; 5. Hybrid actuator; 6. Pressure sensor; 7. Inflation pump; 8. Suction pump; 11. Silicone airbag sheet; 12. Elastic air guide base; 13. Air chamber; 14. Air guide channel; 15. Spring silicone fixing seat; 16. First sub-nonwoven fabric; 17. Second sub-nonwoven fabric; 18. Third sub-nonwoven fabric; 19. Bending sensor; 20. Air inlet; 21. First spring; 22. Second spring. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0047] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0048] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed during use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0049] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0050] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0051] Example 1

[0052] like Figures 2 to 4 As shown, a hybrid actuator combining shape memory alloy and soft composite structure includes a flexible drive unit 1 and an SMA spring unit 2. The flexible drive unit 1 includes a silicone airbag sheet 11, an elastic air-conducting base 12, and a non-woven fabric.

[0053] The silicone airbag 11 is fixed on the elastic air-guiding base 12. There are multiple silicone airbags 11, and each silicone airbag 11 is parallel to each other and distributed at equal intervals. The silicone airbag 11 has an air cavity 13. The elastic air-guiding base 12 has an air-guiding channel 14. The non-woven fabric is fixed on the side of the elastic air-guiding base 12 away from the silicone airbag 11.

[0054] The elastic air-conducting base 12 is provided with a spring silicone fixing seat 15 on the side away from the silicone airbag sheet 11. The SMA spring unit 2 is fixed on the spring silicone fixing seat 15, and the axial direction of the spring silicone fixing seat 15 is parallel to the distribution direction of the silicone airbag sheet 11.

[0055] Working principle: Air is pumped into the air channel 14 inside the elastic air-conducting base 12, thereby pressurizing the air chamber 13. The silicone air bladder 11 expands, causing the upper surface of the elastic air-conducting base 12 to extend. However, the smaller surface of the elastic air-conducting base 12 does not extend due to the limitation of the non-woven fabric, causing the elastic air-conducting base 12 to bend downwards. At the same time, the SMA spring unit 2 at the lower end of the elastic air-conducting base 12 is heated and contracts, which, together with the spring silicone fixing seat 15, causes the lower surface of the elastic air-conducting base 12 to contract and bend.

[0056] The upper end of the elastic air-conducting base 12 is equipped with an airbag that drives the upper surface to extend, while the lower end is equipped with non-woven fabric to restrict the extension of the lower surface. This, combined with the contraction of the SMA spring unit 2, further increases the deformation difference between the two surfaces of the elastic air-conducting base 12, thereby accelerating the bending motion of the actuator, generating a greater output force, and improving the actuator's response speed. Compared to existing structures that only rely on airbag distribution to bend the actuator, this solution can improve the deformability of the flexible actuator while maintaining a small volume. This is beneficial for optimizing the volume and weight of the hand exoskeleton and promotes structural optimization of the hand exoskeleton.

[0057] Specifically, the upper part of the hybrid actuator's airbag is connected to the airway 20 via an air tube; the lower shape memory alloy springs are arranged side by side at the bottom of the airbag, and the shape memory alloy springs are connected in series via wires; when the hybrid actuator is driven, the upper airbag is inflated through the air tube connected to the air pump. Since the bottom non-woven fabric restricts the extension of the bottom of the airbag as a whole, after the inner wall of the air chamber is inflated, the air chamber expands and interacts, and the airbag will bend towards the bottom.

[0058] Preferred implementation methods, such as Figure 3 As shown, the nonwoven fabric includes a first sub-nonwoven fabric 16, a second sub-nonwoven fabric 17 and a third sub-nonwoven fabric 18 that are distributed sequentially at intervals. The first sub-nonwoven fabric 16 and the third sub-nonwoven fabric 18 are symmetrically distributed at both ends of the elastic air-conducting base 12.

[0059] Furthermore, the first sub-nonwoven fabric 16 and the third sub-nonwoven fabric 18 are sheet-like structures, and the second sub-nonwoven fabric 17 includes multiple filamentous nonwoven fabric units, each filamentous nonwoven fabric unit is evenly distributed and is perpendicular to the SMA spring unit 2.

[0060] By setting two sheet-like nonwoven fabrics and a middle filament-like nonwoven fabric on the lower surface of the elastic air-conducting base 12, the sheet-like nonwoven fabrics on both sides will restrict the radial and axial stretching effect of the bottom silicone, while the filament-like nonwoven fabric will restrict the radial stretching of the middle silicone at the bottom of the airbag, so that the middle silicone can stretch axially and achieve a certain length compensation for finger joint bending.

[0061] In this embodiment, as Figure 4 As shown, the SMA spring unit 2 includes a first spring 21 and a second spring 22, which are symmetrically mounted at both ends of the spring silicone mounting base 15. The first spring 21 and the second spring 22 are connected in series via wires. During the driving of the shape memory alloy spring, the shape memory alloy spring is subjected to constant temperature control.

[0062] Specifically, there are multiple spring silicone mounting bases 15, all evenly spaced. A gap is provided between the SMA spring unit 2 and the lower surface of the elastic air-conducting base 12, preventing the shape memory alloy spring from contacting the base plate. Optionally, the SMA spring unit 2 in this invention can be not only a spring-shaped shape memory alloy, but also a sheet-like or wire-like shape memory alloy. It mainly utilizes the characteristic of shape memory alloy to shrink when heated by electricity, providing driving force for the shrinkage of the lower surface of the elastic air-conducting base 12.

[0063] Specifically, multiple shape memory alloy springs are placed side by side at the bottom of the airbag and are tightly fixed to the bottom of the airbag by multiple silicone bases, and the springs do not contact the bottom surface of the airbag. The shape memory alloy springs are connected in series with each other by wires. Utilizing the shape memory effect of the shape memory alloy, the shape memory alloy springs are heated by electric drive, causing the shape memory alloy springs to heat up and generate axial contraction movement, which in turn causes the bottom of the airbag to bend.

[0064] In this embodiment, as Figure 5 As shown, a bending sensor 19 is provided at the bottom of the silicone airbag sheet 11 to detect the bending speed of the elastic air-conducting base 12. Optionally, the silicone airbag sheet 11 in this embodiment can adopt other elastic forms, so that the silicone airbag sheet 11 deforms after the air cavity is inflated, providing a driving force for stretching the upper surface of the elastic air-conducting base 12.

[0065] Specifically, in the combined drive process of the airbag and shape memory alloy spring, the current passing through the shape memory alloy spring is controlled by a bending sensor at the bottom of the airbag, ensuring that the spring contracts faster than the airbag inflates and bends, thus guaranteeing the synergy of the combined drive.

[0066] This invention addresses the issues of large size and low output force in pneumatic hand exoskeletons by designing a hand exoskeleton driven by a combination of silicone airbags and SMA springs. This design meets the requirements of small size and high output force, facilitating rapid driving of bending movements of each finger joint.

[0067] Example 2

[0068] like Figure 1 As shown, this embodiment provides a hand exoskeleton, including a hybrid actuator of shape memory alloy and soft composite structure provided in the embodiment. The hand exoskeleton also includes a glove 3, a solenoid valve 4, an air pump and a power supply. There are multiple hybrid actuators 5. Each finger joint on the glove 3 is provided with a hybrid actuator 5. Each hybrid actuator 5 is connected to the air pump through the solenoid valve 4 and the power supply is connected to the SMA spring unit 2.

[0069] The aforementioned hand exoskeleton also includes a pressure sensor 6, and the air pump includes an inflation pump 7 and a de-inflation pump 8. The inflation pump 7 and the de-inflation pump 8 are respectively connected to a solenoid valve through the pressure sensor 6. When the air pressure in the air circuit is higher than the permissible value, the inflation pump 7 is turned off and the de-inflation pump 8 is turned on.

[0070] The glove 3 is equipped with an insulating heat strip, on which the hybrid actuator is fixed to isolate the high temperatures generated by the SMA spring unit 2 during operation. This prevents hand injury and ensures user safety. It also rapidly reduces the air pressure in the finger air passages to a suitable level, ensuring safety while preventing damage to the airbag structure.

[0071] Specifically, the soft hand exoskeleton includes 14 hybrid actuators driven by a combination of shape memory alloy springs and airbags, multiple inflation pumps, multiple deflation pumps, and solenoid valves. The hybrid actuators are fixed to the outer glove of the pneumatic hand exoskeleton by elastic bands, with the installation positions corresponding to the joints of each finger. Except for the thumb, which has two actuators, each finger has three actuators.

[0072] The specific workflow of this hand exoskeleton is as follows:

[0073] (1) Activate the pneumatic exoskeleton, set the target position, and the system begins to read the set position and the current position;

[0074] (2) When starting, first start the air pump, and then drive the corresponding hybrid actuator by controlling the switching of each solenoid valve through the circuit, thereby realizing the corresponding joint movement;

[0075] (3) When the air pressure sensor detects that the air pressure inside the airbag of the hybrid actuator has reached the target value, in the gripping mode, if you want to maintain the joint position, close the solenoid valve of the actuator that has reached the air pressure target value; in the rehabilitation mode, if you want the joint to reciprocate, close the inflation pump and open the depressurization pump to quickly reduce the air pressure in the air circuit. Then, according to the air pressure value in the air circuit, after reaching the inflation target value, close the depressurization pump and open the inflation pump at the same time, repeating the cycle to achieve hand joint rehabilitation training.

[0076] This hand exoskeleton can control the joints of the five fingers to remain at any position within the range of human hand movement. It uses air pressure sensors to ensure user safety, and the use of motor-controlled air pumps and air pumps greatly improves driving efficiency, simplifies the size and weight of the exoskeleton structure, and enhances the portability of the hand exoskeleton.

[0077] Example 3

[0078] This embodiment is basically the same as Embodiment 1, except that, as Figures 6 to 9 As shown, this embodiment provides a torque verification method based on the hybrid actuator in Embodiment 1. The modeling and analysis steps are as follows:

[0079] Parameter description: Let Δb be the width difference between the expanded air cavity and the initial state, a be the width of the air cavity, b be the side length of the inner square air cavity, t be the wall thickness of the axial surface of the air cavity, L be the length of the air passage between adjacent air cavities, w be the width of the square air passage, e be the thickness of the silicone at the top of the air passage, f be the thickness of the silicone at the bottom of the air passage, d be the spacing between air cavities, R be the radius of the air cavity circle, r be the radius of the contact surface circle between adjacent air cavities, C1 and C2 be the parameters of the constitutive model, n be the number of air cavities, G be the SMA shear modulus, N be the effective number of spring coils, d be the spring wire diameter, D be the spring diameter, and λ be the initial length of the spring. In the modeling, θ is... 气腔 Abbreviated as θ.

[0080] The relationship between input pressure p and the expansion angle of the internal square air cavity:

[0081]

[0082] The bending angle formed by the expansion of a single air cavity:

[0083]

[0084] The bending angle formed by the inflation of the entire airbag:

[0085]

[0086] Expansion force is generated by single-cavity contact:

[0087]

[0088] The total bending moment M generated by the composite actuator on the fixed end 总 :

[0089] M 总 =M 气腔 +M 气道 +M sma

[0090] Assuming the distance from lever arm l to the contact force F of the air chamber is fixed and equal to the distance from the center of the square air chamber to the bottom neutral axis, the driving torque M generated by the airbag on the fixed end point 气腔 (n is the number of air chambers):

[0091]

[0092] Let the input air pressure p represent the bending moment generated on the support:

[0093]

[0094] The torque M generated by the SMA spring on the fixed end sma (λ is the distance from the SMA spring to the neutral axis):

[0095]

[0096] The total bending moment M generated by the obtained composite actuator at the fixed end 总 By comparing with actual requirements, the torque of the complete drive can be verified.

[0097] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A hybrid actuator combining shape memory alloy and soft composite structure, characterized in that, It includes a flexible drive unit (1) and an SMA spring unit (2). The flexible drive unit (1) includes a silicone airbag sheet (11), an elastic air-conducting base (12), and a non-woven fabric. The silicone airbag sheet (11) is fixed on the elastic air-guiding base (12). There are multiple silicone airbag sheets (11), and each silicone airbag sheet (11) is parallel to each other and distributed at equal intervals. The silicone airbag sheet (11) is provided with an air cavity (13). The elastic air-guiding base (12) is provided with an air-guiding channel (14). The non-woven fabric is fixed on the side of the elastic air-guiding base (12) away from the silicone airbag sheet (11). The elastic air-conducting base (12) is provided with a spring silicone fixing seat (15) on the side away from the silicone airbag sheet (11). The SMA spring unit (2) is fixed on the spring silicone fixing seat (15), and the axial direction of the spring silicone fixing seat (15) is parallel to the distribution direction of the silicone airbag sheet (11).

2. The hybrid actuator of shape memory alloy and soft composite structure according to claim 1, characterized in that, The nonwoven fabric includes a first sub-nonwoven fabric (16), a second sub-nonwoven fabric (17) and a third sub-nonwoven fabric (18) that are distributed at intervals in sequence. The first sub-nonwoven fabric (16) and the third sub-nonwoven fabric (18) are symmetrically distributed at both ends of the elastic air-conducting base (12). The first sub-nonwoven fabric (16) and the third sub-nonwoven fabric (18) are sheet-like structures. The second sub-nonwoven fabric (17) includes multiple filamentous nonwoven fabric units, each filamentous nonwoven fabric unit is evenly distributed and is perpendicular to the SMA spring unit (2).

3. The hybrid actuator of shape memory alloy and soft composite structure according to claim 1, characterized in that, The SMA spring unit (2) includes a first spring (21) and a second spring (22). The first spring (21) and the second spring (22) are symmetrically installed at both ends of the spring silicone mounting base (15). The first spring (21) and the second spring (22) are connected in series by a wire.

4. The hybrid actuator of shape memory alloy and soft composite structure according to claim 3, characterized in that, The number of spring silicone fixing seats (15) is multiple, and each spring silicone fixing seat (15) is distributed at equal intervals.

5. The hybrid actuator of shape memory alloy and soft composite structure according to claim 1, characterized in that, A gap is provided between the SMA spring unit (2) and the lower surface of the elastic air guide base (12).

6. The hybrid actuator of shape memory alloy and soft composite structure according to claim 1, characterized in that, The bottom of the silicone airbag sheet (11) is provided with a bending sensor (19) for detecting the bending speed of the elastic air guide base (12).

7. A hand exoskeleton, characterized in that, The hand exoskeleton includes a shape memory alloy and soft composite structure hybrid actuator as described in any one of claims 1-6. The hand exoskeleton also includes a glove (3), a solenoid valve (4), an air pump and a power supply. The number of hybrid actuators (5) is multiple. Each finger joint on the glove (3) is provided with a hybrid actuator (5). Each hybrid actuator (5) is connected to the air pump through the solenoid valve (4). The power supply is connected to the SMA spring unit (2).

8. A hand exoskeleton according to claim 7, characterized in that, It also includes a pressure sensor (6), and the air pump includes an inflation pump (7) and a depressurization pump (8). The inflation pump (7) and the depressurization pump (8) are respectively connected to a solenoid valve through the pressure sensor (6); when the air pressure in the air circuit is higher than the permissible value, the inflation pump (7) is turned off and the depressurization pump (8) is turned on.

9. A hand exoskeleton according to claim 7, characterized in that, The glove (3) is provided with an insulating heat strip, and the hybrid driver is fixed on the insulating heat strip to insulate the heat generated when the SMA spring unit (2) is working.

10. A torque verification method for a hybrid actuator, characterized in that, Based on a hybrid actuator of shape memory alloy and soft composite structure according to any one of claims 1-6, the method includes the following steps: Determine the relationship between the input pressure and the expansion angle of the square air cavity inside the silicone airbag; Calculate the bending angle formed by the expansion of the air cavity of a single silicone airbag, and further calculate the bending angle formed by the expansion of the air cavities of all silicone airbags. Calculate the expansion force generated by the contact of a single silicone airbag cavity; Calculate and sum the driving torque generated by the silicone airbag on the fixed point, the torque of the input air pressure on the elastic air guide base, and the torque generated by the SMA spring on the fixed end to obtain the total torque of the actuator on the fixed end. Compare the total torque with the preset torque to determine whether it meets the requirements. The expression for the total torque of the actuator about the fixed end is: In the formula: Δb is the difference in width between the expanded air cavity and the initial state, a is the width of the air cavity, b is the side length of the inner square air cavity, t is the wall thickness of the axial surface of the air cavity, L is the length of the airway between adjacent air cavities, w is the width of the square airway, e is the thickness of the silicone at the top of the airway, f is the thickness of the silicone at the bottom of the airway, d is the interval between air cavities, R is the radius of the air cavity circle, r is the radius of the contact surface circle between adjacent air cavities, C1 and C2 are the parameters of the silicone constitutive model, n is the number of air cavities, G is the SMA shear modulus, N is the effective number of spring coils, d is the spring wire diameter, D is the spring diameter, λ is the initial length of the spring, and θ is the bending angle formed by the inflation of all air bladders.

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