CN-122008171-A - Shape memory alloy driving actuator with sectional rigidity adjustable and control method thereof

CN122008171ACN 122008171 ACN122008171 ACN 122008171ACN-122008171-A

Abstract

The invention belongs to the technical field of intelligent actuators and flexible drivers, and relates to a sectional rigidity-adjustable shape memory alloy driving actuator and a control method thereof. The actuator comprises a flexible shell, an isolation element, a shape memory alloy driving element and a phase-change stiffness regulating material, wherein the isolation element divides the flexible shell into a plurality of sections of cavity structures which are axially arranged, the phase-change stiffness regulating material is filled in each cavity, the phase-change temperature is not completely the same, and each temperature parameter and each driving force meet a preset matching relation. The control method is that the phase-change rigidity regulating material is sequentially phase-changed to realize the sequential unlocking of the equivalent rigidity of the cavity by controlling the heating temperature of the shape memory alloy driving element, and the multistage controllable equivalent rigidity regulation can be realized under a single driving source. The actuator provided by the invention has a simple structure and programmable response, and is suitable for the fields of soft robots, deformable support structures, intelligent execution systems and the like.

Inventors

WANG GANG
LI XIAN
XIAO RU
SUN HENGDA
ZHU YUWEN
ZHANG GUOQING
LIU YUEXING
ZHU MEIFANG

Assignees

东华大学
愉悦家纺有限公司

Dates

Publication Date: 20260512
Application Date: 20260410

Claims (10)

1. A segmented stiffness-adjustable shape memory alloy driven actuator, comprising: A flexible housing having a hollow cylindrical structure; The isolating element is used for dividing the hollow part of the flexible shell into at least two sections and is of a cavity structure which is sequentially arranged along the axial direction of the flexible shell; a shape memory alloy driving element penetrating all the cavity structures along the axial direction of the flexible housing; The phase-change rigidity regulating materials are respectively filled in the cavity structures, and are materials with phase-change temperature, rigidity state when the phase-change temperature is lower than the phase-change temperature and softening state when the phase-change temperature is higher than or equal to the phase-change temperature; The phase change temperatures of the phase change stiffness regulating materials in different cavity structures are not completely the same, the lowest phase change temperature is marked as T min , the highest phase change temperature is marked as T max , the austenitizing completion temperature of the shape memory alloy driving element is marked as A f , the highest stable temperature which can be reached after the shape memory alloy driving element is electrified is marked as T s , and the environmental temperature is marked as T e ,T min 、A f 、T max which is larger than T e and smaller than T s ; along a certain direction parallel to the axial direction of the flexible shell, for any two adjacent cavity structures, the phase change temperature of the phase change rigidity regulating material positioned in the former cavity structure is greater than or equal to the phase change temperature of the phase change rigidity regulating material positioned in the latter cavity structure; the driving force generated by the shape memory alloy driving element in the austenitizing process is larger than the minimum force required by the reversible deformation of the flexible shell, larger than the structural resistance when any phase change rigidity regulating material is in a softened state and smaller than the structural resistance when any phase change rigidity regulating material is in a rigid state.
2. A segmented stiffness-adjustable shape memory alloy actuation actuator according to claim 1, wherein T e <T min ≤A f ≤T max <T s .
3. The segmented stiffness-adjustable shape memory alloy actuator of claim 1, wherein the phase transition temperature of the phase transition stiffness-controlling material is 40-100 ℃.
4. The segmented stiffness-adjustable shape memory alloy actuator of claim 1, wherein the phase change stiffness-controlling material undergoes a solid-liquid phase change, a glassy-rubbery transition, a solid-solid phase change, a crystalline-melt transition, or a reversible cross-linking transition after being at or above the phase change temperature.
5. The segmented stiffness-adjustable shape memory alloy actuator of claim 4, wherein the phase-change stiffness-controlling material is a phase-change material or a phase-change composite material formed by compounding a phase-change material with a heat-conducting filler, and the phase-change material is at least one selected from the group consisting of a metal phase-change material, a metal alloy phase-change material, an organic phase-change material, an inorganic salt phase-change material, a thermoplastic polymer phase-change material, and a hydrogel phase-change material.
6. The segmented stiffness-adjustable shape memory alloy actuator of claim 1, wherein the flexible housing is in the form of a hollow cylinder, a hollow elliptical cylinder or a hollow polygonal cylinder, and is made of silicone rubber, polyurethane elastomer, thermoplastic elastomer, natural rubber or synthetic rubber.
7. The segmented stiffness-adjustable shape memory alloy actuator of claim 1, wherein the isolation element is a thermally insulating layer or a thermally resistive structure.
8. A segmented stiffness-adjustable shape memory alloy actuation actuator according to claim 1, wherein the shape memory alloy actuation element is a shape memory alloy spring or a shape memory alloy fiber.
9. The segmented stiffness-adjustable shape memory alloy actuation actuator of claim 1, further comprising: A power module for powering the shape memory alloy drive element; And the control module is used for controlling the power supply current and the power supply time of the power supply module.
10. The driving control method of the sectional rigidity-adjustable shape memory alloy driving actuator according to any one of claims 1 to 9, wherein power is continuously supplied to the shape memory alloy driving element, so that the temperature of the shape memory alloy driving element is gradually increased and sequentially reaches the phase transition temperature of the phase transition rigidity regulating material in each cavity structure, and therefore, the sequential unlocking and sectional regulation of the equivalent rigidity of each cavity structure are realized.

Description

Shape memory alloy driving actuator with sectional rigidity adjustable and control method thereof Technical Field The invention belongs to the technical field of intelligent actuators and flexible drivers, and relates to a sectional rigidity-adjustable shape memory alloy driving actuator and a control method thereof. Background The shape memory alloy actuator has the advantages of large output force and compact structure, is widely researched and applied in flexible driving fields such as soft robots, wearable rehabilitation medical devices, intelligent flexible supporting structures and the like, and is one of core components of a flexible execution system. In such application scenarios, the actuator needs to have both supporting capability and structural flexibility, and the shape memory alloy actuator with single constant equivalent stiffness cannot meet the dynamic equivalent stiffness regulation requirements of different working stages, so that the variable equivalent stiffness technology becomes the key research and development direction of the actuator, and various equivalent stiffness regulation schemes have been proposed in the prior art. Patent application CN117961967A discloses a variable equivalent stiffness flexible rod structure and an actuator, and the technology adjusts and controls modulus distribution by adjusting the quantity, the size and the arrangement mode of shape memory alloys or matching different elastic bodies, and realizes the equivalent stiffness adjustment of the flexible rod by utilizing the deformation of the shape memory alloy so as to adapt to the requirement of multiple scenes on equivalent stiffness. The technology has the obvious defects that the equivalent stiffness is regulated and controlled by a plurality of shape memory alloys to act independently, a multi-path current regulation and control system is needed to be matched, the problems of complex overall structure of an actuator, high operation energy consumption, high difficulty in cooperative control of a plurality of driving parts and high equipment operation failure rate are caused, meanwhile, the scheme realizes the equivalent stiffness regulation by means of the modulus change of an elastomer, the equivalent stiffness can only be continuously graded and has limited change amplitude, the modulus change can only be realized by a plurality of times, the locking-unlocking type equivalent stiffness step mutation can not be completed, and the application scene that the equivalent stiffness mutation has hard requirements such as a soft robot, a flexible supporting structure and the like can not be satisfied. In addition, the technology does not have the cooperative work capability of 'local compliance and integral support', and the shape memory alloy can cause the synchronous change of the integral equivalent rigidity of the flexible rod when the action of adjusting the equivalent rigidity, so that the effects of local area compliance deformation and rigid support of other areas can not be realized, and the actual requirements of soft robots, wearable equipment and the like on accurate regulation and control of the local equivalent rigidity can not be met. In the whole, the prior art related to variable equivalent stiffness of the shape memory alloy actuator realizes equivalent stiffness change by means of multi-support structure modulus distribution regulation or multi-drive control, is generally difficult to realize multi-section independent equivalent stiffness regulation under a single drive source, lacks an effective sequential and gradient equivalent stiffness regulation mechanism, has the problems of limited equivalent stiffness change range and no local equivalent stiffness accurate regulation capability, is difficult to adapt to the use requirements of scenes such as a soft robot, a wearable rehabilitation device and the like on the actuator with simple structure, sectional sequential equivalent stiffness regulation, local compliance and integral support, and needs to develop a novel shape memory alloy drive actuator to solve the problems. Disclosure of Invention The invention aims to solve the problems in the prior art and provides a sectional rigidity-adjustable shape memory alloy driving actuator and a control method thereof. In order to achieve the above purpose, the invention adopts the following technical scheme: A segmented stiffness-adjustable shape memory alloy driven actuator, comprising: A flexible housing having a hollow cylindrical structure; The isolating element is used for dividing the hollow part of the flexible shell into at least two sections and is of a cavity structure which is sequentially arranged along the axial direction of the flexible shell; a shape memory alloy driving element penetrating all the cavity structures along the axial direction of the flexible housing; The phase-change rigidity regulating materials are respectively filled in the cavity structures, and are materials wi