CN111823218A - A variable stiffness knee exoskeleton robot based on shape memory alloy - Google Patents

Abstract

Translated fromChinese

一种基于形状记忆合金的变刚度膝关节外骨骼机器人，属于人机融合领域，包括大腿支件、小腿支件、轴承座支撑座、膝关节传动件、膝关节电机、变刚度模块。变刚度模块固定在小腿支件一侧，上部通过膝关节传动件与膝关节法兰座相连，变刚度模块内部记忆合金可实现刚度调节。膝关节电机与大腿支件固连，提供动力。大腿支件与小腿支件保持平行关系。轴承座支撑座上端与大腿支件底部固连，利用内部轴承实现膝关节的回转功能。轴承座输出端片与小腿支件固连，用于带动小腿支件运动。本发明以形状记忆合金作为驱动原理，提升外骨骼整体的机动性能；变刚度外骨骼膝关节可以有效辅助穿戴者行走；材料均采用美铝合金，可有效承载外界力，保护穿戴者。

A variable-stiffness knee joint exoskeleton robot based on shape memory alloy belongs to the field of human-machine fusion, and includes a thigh support, a calf support, a bearing seat support, a knee joint transmission, a knee joint motor, and a variable stiffness module. The variable stiffness module is fixed on one side of the calf support, the upper part is connected with the knee joint flange seat through the knee joint transmission member, and the internal memory alloy of the variable stiffness module can realize the stiffness adjustment. The knee joint motor is fixedly connected with the thigh support to provide power. The thigh support is in a parallel relationship with the calf support. The upper end of the bearing seat support seat is fixedly connected with the bottom of the thigh support, and the internal bearing is used to realize the rotation function of the knee joint. The output end piece of the bearing seat is fixedly connected with the calf support and is used to drive the movement of the calf support. The invention uses the shape memory alloy as the driving principle to improve the overall mobility of the exoskeleton; the variable stiffness exoskeleton knee joint can effectively assist the wearer to walk; the material is made of aluminum alloy, which can effectively carry external forces and protect the wearer.

Description

Translated fromChinese

一种基于形状记忆合金的变刚度膝关节外骨骼机器人A variable stiffness knee exoskeleton robot based on shape memory alloy

技术领域technical field

本发明属于人机融合领域，具体涉及一种变刚度膝关节外骨骼机器人。The invention belongs to the field of human-machine fusion, and in particular relates to a variable stiffness knee joint exoskeleton robot.

背景技术Background technique

随着现代战争、医疗对增强、恢复受试群体运动能力的需求不断提升，膝关节外骨骼逐渐成为研究热点。膝关节助力外骨骼机器人是一种可穿戴在操作者身体外部的机械装置，它可以给穿戴者提供支撑、辅助，增强、恢复其运动功能，所以研制膝关节外骨骼机器人具备极大的现实意义。With the increasing demands of modern warfare and medical treatment to enhance and restore the exercise ability of the test group, the knee joint exoskeleton has gradually become a research hotspot. Knee-assisted exoskeleton robot is a mechanical device that can be worn outside the operator's body. It can provide support, assistance, enhancement and recovery to the wearer's movement function. Therefore, the development of a knee-joint exoskeleton robot has great practical significance. .

传统变刚度外骨骼机器人，虽然可以隔离本体与周围环境的接触碰撞，保护受试者安全，适应不同精度、速度、负载需求。但变刚度单元均采用机械结构进行驱动，其结构复杂。导致外骨骼系统体积、重量过大，不能有效应用于外骨骼设备。Although the traditional variable stiffness exoskeleton robot can isolate the contact and collision between the body and the surrounding environment, protect the safety of the subjects, and adapt to different precision, speed, and load requirements. However, the variable stiffness units are driven by mechanical structures, and their structures are complex. As a result, the volume and weight of the exoskeleton system are too large and cannot be effectively applied to exoskeleton equipment.

发明内容SUMMARY OF THE INVENTION

考虑到这种技术背景，为减轻其重量，增强系统机动性能，开发基于形状记忆合金的变刚度下肢外骨骼机器人，其主要原理为将智能材料的材料科学特性与人体下肢运动科学相结合，通过利用智能材料相变过程中输出的力与位移代替传统电机结构驱动变刚度单元，结合传统电机驱动膝关节外骨骼设备。在满足战争、医疗对外骨骼设备需求的基础上，减轻外骨骼自重，增强外骨骼灵活性。Considering this technical background, in order to reduce its weight and enhance the maneuverability of the system, a variable-stiffness lower limb exoskeleton robot based on shape memory alloys was developed. The force and displacement output during the phase transition of the smart material are used to replace the traditional motor structure to drive the variable stiffness unit, and the knee joint exoskeleton device is driven by the traditional motor. On the basis of meeting the needs of war and medical exoskeleton equipment, the weight of the exoskeleton is reduced and the flexibility of the exoskeleton is enhanced.

为了达到上述目的，本发明的技术方案如下：In order to achieve the above object, technical scheme of the present invention is as follows:

一种基于形状记忆合金的变刚度膝关节外骨骼机器人，其结构紧凑简洁，重心布置合理，运动平稳可靠。所述变刚度膝关节外骨骼机器人包括大腿支件1，小腿支件6，轴承座支撑座10，轴承座输出端片9，膝关节法兰座4，膝关节传动件8，膝关节电机3，电机辅助支撑板2，大腿腿部绑缚板11，小腿腿部绑缚板7，变刚度模块5。A variable stiffness knee exoskeleton robot based on shape memory alloy has a compact and simple structure, reasonable center of gravity arrangement, and stable and reliable movement. The variable stiffness knee exoskeleton robot includes athigh support 1, acalf support 6, abearing seat support 10, a bearing seatoutput end piece 9, a knee joint flange seat 4, a kneejoint transmission member 8, and aknee joint motor 3 , the motorauxiliary support plate 2, the thighleg binding plate 11, the calfleg binding plate 7, and thevariable stiffness module 5.

所述变刚度模块5底部固定在小腿支件6一侧，与小腿支件6保持平行，上部通过膝关节传动件8与膝关节法兰座4相连，能够传递膝关节电机3的力矩，利用弹簧压缩实现双向柔性输出，变刚度模块5内部记忆合金可实现刚度调节；所述膝关节电机3通过电机辅助支撑板2与大腿支件1固连，并保持与大腿支件1垂直关系，输出转矩通过膝关节法兰座4和膝关节传动件8传递给变刚度模块5，为外骨骼机器人提供动力；所述大腿支件1与小腿支件6保持平行关系；所述大腿腿部绑缚板11安装在大腿支件1中部，小腿腿部绑缚板7安装在小腿支件6中部，用于人体穿戴时的绑缚固定；所述轴承座支撑座10与轴承座输出端片9通过轴配合相连，上端与大腿支件1底部固连，可以利用内部轴承实现膝关节的回转功能；所述轴承座输出端片9下端与小腿支件6上端固连，用于带动小腿支件6运动。The bottom of thevariable stiffness module 5 is fixed on one side of thecalf support 6, and is kept parallel to thecalf support 6, and the upper part is connected to the knee joint flange seat 4 through the kneejoint transmission member 8, which can transmit the torque of the kneejoint motor 3, using The spring compression realizes bidirectional flexible output, and the internal memory alloy of thevariable stiffness module 5 can realize stiffness adjustment; theknee joint motor 3 is fixedly connected to thethigh support 1 through the motorauxiliary support plate 2, and maintains a vertical relationship with thethigh support 1, and the output The torque is transmitted to thevariable stiffness module 5 through the knee joint flange seat 4 and the kneejoint transmission member 8 to provide power for the exoskeleton robot; thethigh support 1 and thecalf support 6 maintain a parallel relationship; the thigh legs are tied Thebinding plate 11 is installed in the middle of thethigh support 1, and the calfleg binding plate 7 is installed in the middle of thecalf support 6 for binding and fixing when the human body is worn; the bearingseat support seat 10 and the bearing seatoutput end piece 9 The upper end is connected with the bottom of thethigh support 1 through the shaft, and the rotation function of the knee joint can be realized by using the internal bearing; 6 Movement.

进一步的，所述变刚度模块5包括导向装配件501，拉伸弹簧保护导向件502，导向板503，导向套筒504，无油衬套505，保护外壳506，连接扣507，底板508，安装板510，直线位移传感器509，直线位移传感器固定件511和512，直线位移传感器连接件513，记忆合金丝顶部固定件514，导向连接轴515，弹簧516，记忆合金丝518，记忆合金丝绑缚件517，记忆合金丝底部固定件519。所述导向装配件501底部与拉伸弹簧保护导向件502固连，顶部与膝关节传动件8相连，可以将膝关节电机3输出的力矩传递给变刚度模块5。所述拉伸弹簧保护导向件502通过导向连接轴515与导向板503相连，可以沿导向板503中部槽上下移动，导向板503底部与导向套筒504相连。所述导向套筒504通过无油衬套505与保护外壳506配合，用于弹簧的导向，连接扣507连接保护外壳506与底板508，保护外壳506用于保护弹簧内部结构。所述安装板510一侧与小腿支件6固连，与其小腿支件6保持平行，上部连接底板508，起到支承变刚度模块5的作用；所述直线位移传感器509下端通过直线位移传感器固定件511和512安装在保护外壳506外侧，上端通过直线位移传感器连接件513安装在导向套筒504上侧；所述变刚度模块5只具有单向压缩功能，通过两侧对称结构实现变刚度主动元双向柔性设计。当穿戴者出现腿部骤停等特殊情况时，系统由单侧变刚度单元吸收电机3运动力矩。所述弹簧516安装在导向套筒504和保护外壳506内部，其拉伸与压缩变化可以调节变刚度模块5的刚度；所述记忆合金丝顶部固定件514以及记忆合金丝底部固定件519保持平行关系，用于预紧记忆合金丝518；所述记忆合金丝518利用记忆合金丝绑缚件517构成多根并行结构，可以同时增大其收缩力与收缩位移，当温度升高时，记忆合金可以有效收缩，并且交叉绑缚形状记忆合金，可以有效提升变刚度主动单元的输出力与位移。输入承受力单元侧装有热电偶，以此检测形状记忆合金温度，实现对其相变的实时控制，以此调节收缩力和位移。变刚度模块5安装于外骨骼的两侧，与传统电机配合实现外骨骼的变刚度功能。Further, thevariable stiffness module 5 includes aguide assembly 501, a tensionspring protection guide 502, aguide plate 503, aguide sleeve 504, an oil-free bushing 505, aprotective shell 506, aconnection buckle 507, abottom plate 508, and amounting Plate 510,Linear Displacement Sensor 509, LinearDisplacement Sensor Fixtures 511 and 512, Linear DisplacementSensor Connecting Piece 513, Memory Alloy WireTop Fixing 514,Guide Connecting Shaft 515,Spring 516,Memory Alloy Wire 518, Memory AlloyWire Binding Piece 517, memory alloy wirebottom fixing piece 519. The bottom of theguide assembly 501 is fixedly connected with the extensionspring protection guide 502 , and the top is connected with the kneejoint transmission member 8 , which can transmit the torque output by the kneejoint motor 3 to thevariable stiffness module 5 . The extensionspring protection guide 502 is connected with theguide plate 503 through theguide connecting shaft 515 , and can move up and down along the middle groove of theguide plate 503 , and the bottom of theguide plate 503 is connected with theguide sleeve 504 . Theguide sleeve 504 cooperates with theprotective casing 506 through the oil-free bushing 505 for guiding the spring. The connectingbuckle 507 connects theprotective casing 506 and thebottom plate 508, and theprotective casing 506 is used to protect the internal structure of the spring. One side of themounting plate 510 is fixedly connected with thecalf support 6 and is kept parallel to thecalf support 6, and the upper part is connected to thebottom plate 508 to support thevariable stiffness module 5; the lower end of thelinear displacement sensor 509 is fixed by the linear displacement sensor Thecomponents 511 and 512 are installed on the outer side of theprotective casing 506, and the upper end is installed on the upper side of theguide sleeve 504 through the linear displacementsensor connecting piece 513; thevariable stiffness module 5 only has a one-way compression function, and the variable stiffness active through the symmetrical structure on both sides is realized Meta two-way flexible design. When the wearer has a special situation such as sudden leg stop, the system absorbs the motion torque of themotor 3 by the unilateral variable stiffness unit. Thespring 516 is installed inside theguide sleeve 504 and theprotective casing 506, and its tension and compression changes can adjust the stiffness of thevariable stiffness module 5; the memory alloy wiretop fixing member 514 and the memory alloy wirebottom fixing member 519 are kept parallel. Thememory alloy wire 518 is used to pre-tighten thememory alloy wire 518; thememory alloy wire 518 uses the memory alloywire binding member 517 to form a plurality of parallel structures, which can increase its shrinkage force and shrinkage displacement at the same time. It can be effectively contracted and cross-bound shape memory alloy, which can effectively improve the output force and displacement of the variable stiffness active unit. A thermocouple is installed on the side of the input bearing unit to detect the temperature of the shape memory alloy and realize real-time control of its phase transformation, thereby adjusting the shrinkage force and displacement. Thevariable stiffness module 5 is installed on both sides of the exoskeleton, and cooperates with the traditional motor to realize the variable stiffness function of the exoskeleton.

与现有技术相比，本发明的有益效果为：Compared with the prior art, the beneficial effects of the present invention are:

(1)以形状记忆合金作为驱动的新原理，其重量轻，体积小，提升外骨骼整体的机动性能。(1) A new principle driven by shape memory alloys, which is light in weight and small in size, improves the overall mobility of the exoskeleton.

(2)设计了变刚度外骨骼膝关节，可以有效辅助穿戴者行走，具有变刚度功能，在高机动性需求下，具备更好的驱动效果。(2) The variable stiffness exoskeleton knee joint is designed, which can effectively assist the wearer to walk, has the function of variable stiffness, and has a better driving effect under high mobility requirements.

(3)材料均采用美铝合金，其质量轻，强度高，可以有效承载外界力，保护穿戴者。(3) The materials are all made of American aluminum alloy, which is light in weight and high in strength, which can effectively carry external forces and protect the wearer.

附图说明Description of drawings

图1是本发明实例中所用变刚度膝关节外骨骼机器人的整体结构图。FIG. 1 is an overall structural diagram of the variable stiffness knee exoskeleton robot used in the example of the present invention.

图2是本发明实例中所用变刚度膝关节外骨骼机器人的变刚度主动单元模块结构图。FIG. 2 is a structural diagram of the variable stiffness active unit module of the variable stiffness knee exoskeleton robot used in the example of the present invention.

图3是本发明实例中所用变刚度膝关节外骨骼机器人的变刚度主动单元内部记忆合金丝布置形式结构图。3 is a structural diagram of the arrangement of memory alloy wires in the variable stiffness active unit of the variable stiffness knee exoskeleton robot used in the example of the present invention.

图中：1大腿支件，2电机辅助支撑板，3膝关节电机，4膝关节法兰座，5变刚度模块，6小腿支件，7小腿腿部绑缚板，8膝关节传动件，9轴承座输出端片，10轴承座支撑座，11大腿腿部绑缚板；In the picture: 1 thigh support, 2 motor auxiliary support plate, 3 knee joint motor, 4 knee joint flange seat, 5 variable stiffness module, 6 lower leg support, 7 lower leg leg binding plate, 8 knee joint transmission parts, 9 bearing seat output end piece, 10 bearing seat support seat, 11 thigh leg binding plate;

501导向装配件，502拉伸弹簧保护导向件，503导向板，504导向套筒，505无油衬套，506保护外壳，507连接扣，508底板，509直线位移传感器，510安装板，511和512直线位移传感器固定件，513直线位移传感器连接件，514记忆合金丝顶部固定件，515导向连接轴，516弹簧，517记忆合金丝绑缚件，518记忆合金丝，519记忆合金丝底部固定件。501 Guide Assembly, 502 Tension Spring Protection Guide, 503 Guide Plate, 504 Guide Sleeve, 505 Oil-Free Bushing, 506 Protective Housing, 507 Connection Buckle, 508 Base Plate, 509 Linear Displacement Sensor, 510 Mounting Plate, 511 and 512 linear displacement sensor fixing parts, 513 linear displacement sensor connecting parts, 514 memory alloy wire top fixing parts, 515 guide connecting shaft, 516 spring, 517 memory alloy wire binding parts, 518 memory alloy wire, 519 memory alloy wire bottom fixing parts .

具体实施方式Detailed ways

下面结合附图和实例对本发明作进一步说明。The present invention will be further described below in conjunction with the accompanying drawings and examples.

如图1所示，一种变刚度膝关节外骨骼机器人包括大腿支件1，小腿支件6，轴承座支撑座10，轴承座输出端片9，膝关节法兰座4，膝关节传动件8，膝关节电机3，电机辅助支撑板2，大腿腿部绑缚板11，小腿腿部绑缚板7，变刚度模块5。变刚度模块5底部固定在小腿支件6一侧，与小腿支件6保持平行，上部通过膝关节传动件8与膝关节法兰座4相连；膝关节电机3通过电机辅助支撑板2与大腿支件1固连，输出转矩通过膝关节法兰座4和膝关节传动件8传递给变刚度模块5；大腿支件1与小腿支件6保持平行关系；大腿腿部绑缚板11安装在大腿支件1中部，小腿腿部绑缚板7安装在小腿支件6中部；轴承座支撑座10与轴承座输出端片9通过轴配合相连，上端与大腿支件1底部固连；轴承座输出端片9下端与小腿支件6上端固连。As shown in Figure 1, a variable stiffness knee exoskeleton robot includes athigh support 1, acalf support 6, abearing seat support 10, a bearing seatoutput end piece 9, a knee joint flange seat 4, and a kneejoint transmission member 8. Kneejoint motor 3 , motorauxiliary support plate 2 , thigh legbinding plate 11 , calf legbinding plate 7 ,variable stiffness module 5 . The bottom of thevariable stiffness module 5 is fixed on the side of thecalf support 6 and is kept parallel to thecalf support 6, and the upper part is connected to the knee joint flange seat 4 through the kneejoint transmission member 8; theknee joint motor 3 is connected to the thigh through the motorauxiliary support plate 2 Thesupport 1 is fixedly connected, and the output torque is transmitted to thevariable stiffness module 5 through the knee joint flange seat 4 and the kneejoint transmission member 8; thethigh support 1 and thecalf support 6 maintain a parallel relationship; the thighleg binding plate 11 is installed In the middle of thethigh support 1, the calfleg binding plate 7 is installed in the middle of thecalf support 6; the bearingseat support seat 10 is connected with the bearing seatoutput end piece 9 through shaft fitting, and the upper end is fixedly connected with the bottom of thethigh support 1; The lower end of the seatoutput end piece 9 is fixedly connected with the upper end of thecalf support 6 .

如图2和图3所示，一种变刚度膝关节外骨骼机器人，其变刚度模块5还包括导向装配件501，拉伸弹簧保护导向件502，导向板503，导向套筒504，无油衬套505，保护外壳506，连接扣507，底板508，安装板510，直线位移传感器509，直线位移传感器固定件511和512，直线位移传感器连接件513，记忆合金丝顶部固定件514，导向连接轴515，弹簧516，记忆合金丝518，记忆合金丝绑缚件517，记忆合金丝底部固定件519。导向装配件501底部与拉伸弹簧保护导向件502固连，顶部与膝关节传动件8相连；拉伸弹簧保护导向件502通过导向连接轴515与导向板503相连，导向板503底部与导向套筒504相连；导向套筒504通过无油衬套505与保护外壳506配合，连接扣507连接保护外壳506与底板508。安装板510一侧与小腿支件6固连，与小腿支件6保持垂直关系，上部连接底板508；直线位移传感器509下端通过直线位移传感器固定件511和512安装在保护外壳506外侧，上端通过直线位移传感器连接件513安装在导向套筒504上侧；弹簧516安装在导向套筒504和保护外壳506内部；记忆合金丝顶部固定件514以及记忆合金丝底部固定件519保持平行关系；记忆合金丝518利用记忆合金丝绑缚件517构成多根并行结构。As shown in Figures 2 and 3, a variable stiffness knee exoskeleton robot, thevariable stiffness module 5 further includes aguide assembly 501, a tensionspring protection guide 502, aguide plate 503, aguide sleeve 504, and nooil Bushing 505,protective shell 506, connectingbuckle 507,bottom plate 508,mounting plate 510,linear displacement sensor 509, linear displacementsensor fixing parts 511 and 512, linear displacementsensor connecting part 513, memory alloy wiretop fixing part 514, guide connection Shaft 515,spring 516,memory alloy wire 518, memory alloywire binding member 517, memory alloy wirebottom fixing member 519. The bottom of theguide assembly 501 is fixedly connected with the extensionspring protection guide 502, and the top is connected with the kneejoint transmission member 8; the extensionspring protection guide 502 is connected with theguide plate 503 through theguide connecting shaft 515, and the bottom of theguide plate 503 is connected with the guide sleeve Thebarrel 504 is connected; theguide sleeve 504 is matched with theprotective shell 506 through the oil-free bushing 505 , and theconnection buckle 507 connects theprotective shell 506 and thebottom plate 508 . One side of themounting plate 510 is fixedly connected with thecalf support 6, maintains a vertical relationship with thecalf support 6, and the upper part is connected to thebottom plate 508; The lineardisplacement sensor connector 513 is installed on the upper side of theguide sleeve 504; thespring 516 is installed inside theguide sleeve 504 and theprotective casing 506; the memory alloy wiretop fixing member 514 and the memory alloy wirebottom fixing member 519 maintain a parallel relationship; Thewires 518 use memory alloywire binding members 517 to form a plurality of parallel structures.

虽然上文中已经结合附图和实例对本发明进行了描述，然而在不脱离本发明范围的情况下，可对其进行各种改进，且可以用等效物替换其中的部件。因此，本发明并不局限于文中公开的特定实施例，而是包括落入权利要求范围内的所有技术方案。While the invention has been described above with reference to the accompanying drawings and examples, various modifications may be made and equivalents may be substituted for parts thereof without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

以上所述实施例仅表达本发明的实施方式，但并不能因此而理解为对本发明专利的范围的限制，应当指出，对于本领域的技术人员来说，在不脱离本发明构思的前提下，还可以做出若干变形和改进，这些均属于本发明的保护范围。The above-mentioned embodiments only represent the embodiments of the present invention, but should not be construed as a limitation on the scope of the present invention. It should be pointed out that for those skilled in the art, without departing from the concept of the present invention, Several modifications and improvements can also be made, which all belong to the protection scope of the present invention.

Claims (1)

1. The variable-rigidity knee joint exoskeleton robot is characterized by comprising thigh supporting pieces (1), a shank supporting piece (6), a bearing seat supporting seat (10), a bearing seat output end piece (9), a knee joint flange seat (4), a knee joint driving piece (8), a knee joint motor (3), a motor auxiliary supporting plate (2), a thigh leg binding plate (11), a shank leg binding plate (7) and a variable-rigidity module (5);

the bottom of the variable stiffness module (5) is fixed on one side of the shank support piece (6) and is parallel to the shank support piece (6), the upper part of the variable stiffness module is connected with the knee joint flange seat (4) through a knee joint transmission piece (8) and is used for transmitting the moment of the knee joint motor (3), bidirectional flexible output is realized by utilizing spring compression, and stiffness adjustment can be realized by memory alloy in the variable stiffness module (5); the knee joint motor (3) is fixedly connected with the thigh supporting piece (1) through the motor auxiliary supporting plate (2) and keeps a vertical relation with the thigh supporting piece (1), and output torque is transmitted to the variable stiffness module (5) through the knee joint flange seat (4) and the knee joint transmission piece (8) to provide power for the exoskeleton robot; the thigh support (1) and the shank support (6) are kept in parallel; the thigh and leg binding plate (11) is arranged in the middle of the thigh support (1), and the shank and leg binding plate (7) is arranged in the middle of the shank support (6) and used for binding and fixing when a human body wears; the bearing seat supporting seat (10) is connected with the bearing seat output end sheet (9) in a matched mode through a shaft, the upper end of the bearing seat supporting seat is fixedly connected with the bottom of the thigh supporting piece (1), and the rotation function of the knee joint is realized by utilizing an internal bearing; the lower end of the output end piece (9) of the bearing seat is fixedly connected with the upper end of the shank support (6) and is used for driving the shank support (6) to move;

the rigidity-variable module (5) comprises a guide assembly part (501), a tension spring protection guide part (502), a guide plate (503), a guide sleeve (504), an oilless bushing (505), a protection shell (506), a connecting buckle (507), a bottom plate (508), a mounting plate (510), a linear displacement sensor (509), a linear displacement sensor connecting part (513), a memory alloy wire top fixing part (514), a guide connecting shaft (515), a spring (516), a memory alloy wire (518), a memory alloy wire binding part (517) and a memory alloy wire bottom fixing part (519); the variable stiffness module (5) only has a one-way compression function, and realizes the two-way flexible design of the variable stiffness driving element through a symmetrical structure on two sides;

the bottom of the guide assembly part (501) is fixedly connected with the extension spring protection guide part (502), and the top of the guide assembly part is connected with the knee joint transmission part (8) to transmit the torque output by the knee joint motor (3) to the variable stiffness module (5); the extension spring protection guide piece (502) is connected with a guide plate (503) through a guide connecting shaft (515) and can move up and down along a middle groove of the guide plate (503), and the bottom of the guide plate (503) is connected with a guide sleeve (504); the guide sleeve (504) is matched with the protective shell (506) through an oilless bushing (505) and used for guiding the spring, and the connecting buckle (507) is connected with the protective shell (506) and the bottom plate (508); one side of the mounting plate (510) is fixedly connected with the lower leg support (6) and is parallel to the lower leg support (6), and the upper part of the mounting plate is connected with a bottom plate (508) for supporting the variable stiffness module (5); the lower end of the linear displacement sensor (509) is arranged on the outer side of the protective shell (506) through a linear displacement sensor fixing piece, and the upper end of the linear displacement sensor (509) is arranged on the upper side of the guide sleeve (504) through a linear displacement sensor connecting piece (513); the spring (516) is arranged inside the guide sleeve (504) and the protective shell (506), and the stretching and compression changes of the spring can adjust the rigidity of the rigidity changing module (5); the memory alloy wire top fixing piece (514) and the memory alloy wire bottom fixing piece (519) keep a parallel relation and are used for pre-tightening the memory alloy wire (518); the memory alloy wire (518) forms a plurality of parallel structures by utilizing the memory alloy wire binding pieces (517), the contraction force and the contraction displacement of the memory alloy wire can be increased simultaneously, when the temperature rises, the memory alloy contracts effectively, and the shape memory alloy is bound in a crossed mode, so that the output force and the displacement of the variable-stiffness active unit are improved; the thermocouple is arranged on the input bearing force unit side and used for detecting the temperature of the shape memory alloy, realizing the real-time control of the phase change of the shape memory alloy and further adjusting the contraction force and the displacement.

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