Flexible Wearable Knee Exoskeleton for Assisting the Elderly in Standing and Walking

Abstract

The present invention discloses a flexible wearable knee exoskeleton for assisting the elderly in standing and walking, which includes a unidirectional bending variable stiffness knee joint actuator and a motion intention detection and control system; the unidirectional bending variable stiffness knee joint actuator includes a vacuum bag with an air pipe joint and a gear group structure in the vacuum bag; the gear group structure includes a central gear, a limit gear, an interlocking gear, a transition gear, and an end gear, and adjacent gears are connected to each other by a rotating shaft and a connecting rod; bite plate layers are arranged on the inner and outer sides of the gear group structure, bite teeth are arranged on the inner side of the bite plate layer, and foam glue is filled between adjacent bite teeth; a torsion spring is installed on the gear group structure; the motion intention detection and control system includes an inertial measurement unit for obtaining the motion data of the thigh and the calf. After the data obtained by the inertial measurement unit is judged by the control chip, the vacuum pump is controlled to pump air or not to pump air, the air pressure in the vacuum bag is controlled, and the stiffness of the unidirectional bending variable stiffness knee joint actuator is controlled. The present invention is suitable for the elderly to use.

Description

Technical Field

[0001] The present invention relates to the technical field of exoskeletons, and particularly to a flexible wearable knee exoskeleton for assisting the elderly in standing and walking. Background Art

[0002] Flexible wearable exoskeletons are electromechanical systems that use flexible materials to be worn or wrapped around the human torso, aiming to assist and enhance human motor abilities in various scenarios. From providing additional power to assist the wearer's movement to assisting in exercising the wearer's muscles, etc., it covers many fields. Compared with rigid exoskeletons, it has the characteristics of high wearing comfort, light weight, and good safety, and has received extensive attention in recent years.

[0003] Flexible wearable exoskeletons are divided into two types according to the driving method: exoskeletons based on pneumatic driving methods and exoskeletons based on cable-driven driving methods. However, compared with rigid exoskeletons, both of these two types of flexible exoskeletons have problems such as relatively small output force / moment, long response time, and low control accuracy, which are related to the structural characteristics of the flexible exoskeleton itself and the immaturity of related technologies. At the same time, compared with rigid exoskeletons, due to the unclear joint positions of flexible exoskeletons and the fact that the actuators are distributed along the body, commonly used locking devices in rigid exoskeletons, from mechanical locking devices to electromagnetic brakes, cannot be directly integrated into the soft exoskeleton without affecting its wear resistance.

[0004] Pneumatic knee exoskeletons generally can use variable stiffness structures as actuators, that is, changing the pressure difference inside and outside the airbag to achieve changes in structural stiffness. The pneumatic variable stiffness joint actuator disclosed in CN114406986A can better solve the problem of variable stiffness of the actuator, but this joint actuator is bent bidirectionally in the flexible state, and the bending angle cannot be limited, which does not meet the requirement of the human knee joint bending unidirectionally at a certain angle. And there are problems that it cannot provide force / moment during the process of standing to sitting and sitting to standing, the maximum achievable stiffness is relatively small, and there is insufficient output torque, etc., which is not enough to meet the needs of assisting the elderly in movement. Summary of the Invention

[0005] The purpose of the present invention is to address the problems in the prior art, and provide a flexible wearable knee exoskeleton for assisting the elderly in standing and walking with gear meshing limit and torsion spring energy storage, which is simple to manufacture, low in cost, light in weight, ergonomic, high in wearing comfort, and its safety and comfort are suitable for the elderly population. It is a knee joint booster or equipment, which is a knee joint flexible exoskeleton that can prevent the elderly from falling when standing and walking due to knee bending, and at the same time provide auxiliary torque during the process of the elderly standing to sitting and sitting to standing, and can exercise their leg muscles to maintain or enhance walking ability.

[0006] The technical solution adopted to achieve the purpose of the present invention is as follows:

[0007] A flexible wearable knee exoskeleton for assisting the elderly in standing and walking, comprising a unidirectional bending variable stiffness knee joint driver and a motion intention detection and control system; the unidirectional bending variable stiffness knee joint driver includes a vacuum bag with a tracheal joint and a gear group structure arranged in the vacuum bag; the gear group structure includes a central gear and two groups of side gear groups located on both sides of the central gear; each group of side gear groups successively includes an engaging limit gear, an interlocking gear, a transition gear, and a terminal gear; the limit gear meshes with the central gear, and adjacent gears are connected to each other through a rotating shaft and a connecting rod; an outer engaging sheet layer and an inner engaging sheet layer are respectively arranged on the outer side and the inner side of the bending surface of the gear group structure, and a plurality of spaced engaging teeth that cooperate with the gears of the gear group structure are respectively arranged on the inner sides of the outer engaging sheet layer and the inner engaging sheet layer, and foam glue is filled between adjacent engaging teeth; a torsion spring is installed on the gear group structure for converting negative work into elastic potential energy during the movement of the lower limbs and releasing it when needed.

[0008] The motion intention detection and control system includes an inertial measurement unit. When in use, it is bound to the user through a fixing device together with the unidirectional bending variable stiffness knee joint driver, and is used to obtain the motion data of the thigh and calf when the user moves; the unidirectional bending variable stiffness knee joint driver is connected to a vacuum pump, and the motion data obtained by the two inertial measurement units is transmitted to a control chip. After the state is judged by a motion intention detection algorithm, the control data is transmitted to a motor driver to control the vacuum pump to pump air or not pump air, so as to accurately control the air pressure in the vacuum bag, thereby controlling the stiffness of the unidirectional bending variable stiffness knee joint driver.

[0009] Among them, the torsion spring is made of spring steel and is fixed and connected through the rotating shaft.

[0010] Among them, the torsion spring includes a main torsion spring and a secondary torsion spring; the main torsion spring is installed on the main rotating shaft connected to the shaft hole of the central gear, and the secondary torsion spring is installed on the secondary rotating shaft connected to the shaft hole of the interlocking gear.

[0011] Among them, the vacuum bag is sealed with a thermoplastic polyurethane material.

[0012] Among them, the central gear, limit gear, interlocking gear, transition gear, and terminal gear are made by 3D printing using a liquid photosensitive resin material.

[0013] Among them, the engaging teeth are obtained by 3D printing using a liquid photosensitive resin material.

[0014] Among them, the motor driver is powered by a lithium battery.

[0015] Among them, the unidirectional bending variable stiffness knee joint driver is fixed to the knee joint position of the user through a fixing device.

[0016] Among them, the fixing device includes an outer packaging cloth bag, a magic tape strap fixed to the outer surface of the outer packaging cloth bag, and a metal ring installed on the magic tape strap. The tightness of the unidirectional bending variable stiffness knee joint driver is adjusted by passing the magic tape strap through the metal ring and adjusting the sticking position of the magic tape; one side of the outer packaging cloth bag is open and provided with a zipper for facilitating the taking and placing of the unidirectional bending variable stiffness knee joint driver; the inertial measurement unit is fixed to the magic tape strap.

[0017] Among them, two central gear tooth grooves are arranged on the circumferential surface of the central gear, which cooperate with the central gear limit teeth of the corresponding two limit gears. The limit gear has two limit gear engaging tooth grooves that cooperate with the engaging teeth on both sides and an interlocking gear engaging tooth groove that cooperates with the limit gear of the interlocking gear; the interlocking gear has two interlocking gear engaging tooth grooves that cooperate with the engaging teeth on both sides and a transition gear engaging tooth groove that cooperates with the interlocking gear of the transition gear.

[0018] The flexible wearable knee joint exoskeleton for assisting the elderly in standing and walking of the present invention combines a torsion spring with the occlusion of a unidirectional bending negative pressure blocking structure, provides a large bending stiffness through the structure interlocking effect under negative pressure, and uses foam glue to avoid structure occlusion under normal pressure to provide a small bending stiffness, thereby increasing the stiffness change ratio. By converting the negative work in the lower limb movement process into elastic potential energy for storage and releasing it when needed, the overall energy efficiency of the exoskeleton is improved, and output force / moment is provided during the process of the elderly sitting down and standing up, enriching the application scenarios of the knee joint flexible exoskeleton.

[0019] The flexible wearable knee joint exoskeleton for assisting the elderly in standing and walking of the present invention can be customized according to specific application objects to meet different application requirements, and has good universality; its motion intention detection module can be calculated and optimized according to the gait characteristics of each person to meet the needs of different people for gait detection and improve the product recognition accuracy. The torsion spring, gear set and occluding sheet layer are based on modular design and can be optimized and customized according to different usage situations to adapt to the usage requirements under different usage environments.

[0020] The flexible wearable knee joint exoskeleton for assisting the elderly in standing and walking of the present invention has the advantages of high control accuracy, short response time, light overall weight, low energy consumption during use, and low manufacturing cost. Its safety and comfort are suitable for long-term use by the elderly population, and its simple manufacturing process and low cost will also contribute to large-scale use. Description of the Drawings

[0021] Figures 1-2 respectively show the schematic diagrams of the use of the flexible wearable knee exoskeleton according to the embodiments of the present invention;

[0022] Figure 3 show the structural schematic diagram of the unidirectional bending variable stiffness knee joint driver according to the embodiments of the present invention;

[0023] Figures 4-5 respectively show the schematic diagrams of the normal pressure state and the negative pressure state of the unidirectional bending variable stiffness knee joint driver according to the embodiments of the present invention;

[0024] Figures 6-7 respectively show the schematic diagrams of the central gear and the limit gear in the fully extended limit position and 11;

[0025] Figures 8-9 respectively show the schematic diagrams of the fixing device according to the embodiments of the present invention;

[0026] Figure 10 show the schematic diagram of the device circuit of the motion intention detection and control system according to the embodiments of the present invention;

[0027] Figure 11 show the control structure schematic diagram of the motion intention monitoring and control system according to the embodiments of the present invention;

[0028] Figure 12 show the schematic diagram of the recognition algorithm of the motion intention monitoring and control system according to the embodiments of the present invention;

[0029] Figure 13 show the control logic schematic diagram of the motion intention detection and control system according to the embodiments of the present invention.

[0030] In the figure:

[0031] 101 - vacuum bag; 102 - tracheal joint; 103 - outer occlusal sheet layer; 104 - inner occlusal sheet layer; 105 - gear group structure; 106 - main torsion spring; 107 - auxiliary torsion spring; 108 - central gear; 109 - limit gear; 110 - interlocking gear; 111 - transition gear; 112 - end gear; 113 - foam adhesive; 114 - occlusal teeth; 201 - outer packaging cloth bag; 202 - magic tape; 203 - fixing ring; 204 - zipper; 301 - inertial measurement unit; 302 - control chip; 303 - motor driver; 304 - lithium battery; 305 - vacuum pump; 306 - air duct. Detailed implementation manners

[0032] The following further describes the present invention in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] In the flexible wearable knee exoskeleton according to the embodiment of the present invention, when the pressure difference inside and outside the vacuum bag is changed, the engagement state between the gear set structure and the corresponding engagement sheet layer changes, affecting the frictional resistance between the internal components and the tensile tension of the engagement sheet layer, and controlling the bending stiffness of the actuator by adjusting the pressure difference.

[0034] The flexible wearable knee exoskeleton according to the embodiment of the present invention is provided with a unidirectional bending variable stiffness knee actuator and a torsion spring for energy storage. By controlling, it can improve the output torque of the flexible actuator and realize a predetermined unidirectional bending angle to meet the needs of the human knee joint, and can be worn by the elderly by controlling its weight and volume.

[0035] The unidirectional bending variable stiffness knee actuator based on the energy storage of the torsion spring and the engagement of the negative pressure blocking structure according to the embodiment of the present invention can convert the negative work in the lower limb movement process into elastic potential energy for storage and release when needed, thereby improving the overall energy efficiency of the exoskeleton and providing output force / torque during the process of the elderly sitting and standing up.

[0036] Reference Figures 1 to 2 As shown, a flexible wearable knee exoskeleton for assisting the elderly in standing and walking includes a motion intention monitoring system 3 based on an inertial measurement unit, a unidirectional bending variable stiffness knee actuator 1, and a corresponding fixing device 2 is provided to fix the product.

[0037] Referring to Figure 3 As shown, the unidirectional bending variable stiffness knee actuator 1 of this embodiment includes an internal structure and a vacuum bag 101 with an air pipe joint 102 left. Referring to Figure 4 And Figure 5 , the internal structure includes a gear set structure 105 and torsion springs arranged on both sides along the length direction of the gear set structure 105, and an outer engagement sheet layer 103 and an inner engagement sheet layer 104 are also provided. Among them, the outer engagement sheet layer 103 is located outside the bending surface of the gear set structure 105, and the inner engagement sheet layer is located inside the bending surface of the gear set structure 105.

[0038] Among them, the gear set structure 105 includes a central gear 108, a limit gear 109, an interlocking gear 110, a transition gear 111 and a terminal gear 112, and the torsion spring is fixed and connected through the rotating shaft of the gear set structure 105.

[0039] In some exceptions of the embodiments, the torsion spring is composed of a main torsion spring 106 and a secondary torsion spring 107.

[0040] Among them, the relative rotation range of the transition gear 111 and the terminal gear 112 is small, and the rotation limit is ignored. The small swing enables the terminal to better adapt to the leg arc while being able to engage tightly and transmit torque.

[0041] Under normal pressure, the foam adhesive 113 can keep a certain distance between the inner and outer interlocking laminates 103 and 104 and the gear set 105, preventing the rack 114 from engaging with the gear set 105, enabling the one-way bending variable stiffness knee joint actuator to bend with a smaller stiffness. The bending range is mainly determined by the relative rotation angle between the limit gear 109 and the central gear 108. At the same time, the main torsion spring 106 and the auxiliary torsion spring 107 play a certain buffering role during the bending process and store the mechanical energy as elastic potential energy.

[0042] When changing from normal pressure to negative pressure, at this time, during the process from bending to straightening, the main torsion spring 106 and the auxiliary torsion spring 107 release energy to provide an auxiliary torque. When the teeth of the limit gear 109 engage with the limit groove of the central gear 108, the final straightening state is reached. The foam adhesive 113 is compressed, and the rack 114 engages and locks with the gear set, and the stiffness of the one-way bending variable stiffness knee joint actuator 1 increases significantly, providing a larger support torque.

[0043] In some embodiments, by changing the elastic moduli of the main torsion spring 106 and the auxiliary torsion spring 107, the magnitudes of the resistance torque and the auxiliary torque in the non-negative pressure bending state can be changed. By modifying the position of the limit groove of the central gear 108 and the parameters of the corresponding engaging teeth, the one-way limit position can be changed.

[0044] Refer to Figures 6 to 7 As shown, when the central gear 108 and the limit gear 109 rotate relative to each other, there are two limit positions: straightening and bending. The straightening limit is limited by the engagement of the limit groove of the central gear 108 and the teeth of the limit gear 109, and the bending limit is limited by the interlocking of the teeth. The two limit positions determine the relative rotation range.

[0045] By modifying the shape design parameters of the central gear 108 and the limit gear 109, the limit positions of their relative rotation can be changed, thereby changing the non-interlocked low stiffness bending range of the one-way bending variable stiffness knee joint actuator 1 under normal pressure.

[0046] Refer to Figure 8 And Figure 9 As shown, the fixing device includes an outer packaging cloth bag 201 for placing the one-way bending variable stiffness knee joint actuator 1, a magic tape strap 202 connected with a fixing ring 203 and fixed to the outer surface of the outer packaging cloth bag 201 by sewing, and further includes a hidden zipper 204 arranged at the opening position on one side of the outer packaging cloth bag, located on the side close to the leg. The one-way bending variable stiffness knee joint actuator 1 and the fixing device 2 form a wearable structure of the exoskeleton system.

[0047] Refer to Figure 10As shown, the motion intention detection control system 3 is composed of two inertial measurement units 301, a control chip 302, a motor driver 303, a lithium battery 304, a vacuum air pump 305, and an air duct 306.

[0048] Reference Figure 11 As shown, when the user exercises, the movement data of the thigh and calf are respectively transmitted to the control chip 302 through the data transmission of the upper and lower inertial measurement units 301. The two inertial measurement units 301 and the control chip 302 are powered by lithium batteries 304. After the state is judged by the movement intention detection algorithm written into the control chip 302 in advance, the movement intention judgment data is transmitted to the motor driver 303. The motor driver 303 is powered by the lithium battery 304 and controls whether the vacuum air pump 305 is pumping air.

[0049] When the control chip 302 determines that the stiffness of the unidirectional bending variable stiffness knee joint driver 1 needs to be increased, it issues a vacuum command to the vacuum air pump 305, and the gas of the unidirectional bending variable stiffness knee joint driver 1 is extracted through the air duct 306, and the unidirectional bending variable stiffness knee joint driver 1 is under negative pressure, thereby providing a supporting torque.

[0050] When the control chip 302 determines that the unidirectional bending variable stiffness knee joint driver 1 needs to reduce its stiffness, it issues a command to the vacuum air pump 305 to stop pumping air, and the gas rushes into the unidirectional bending variable stiffness knee joint driver 1 through the air duct 306, and the unidirectional bending variable stiffness knee joint driver becomes normal pressure.

[0051] Reference Figure 12 As shown, in the embodiment of the present application, the motion intention detection and control system is divided into two stages in the motion intention detection and judgment stage: the walking and standing stage and the sitting and standing stage, and each stage is divided into three states:

[0052] In the walking stance phase, it is divided into the swing phase, the support phase and the standing state;

[0053] The sitting and standing up stage is divided into the sitting process, the standing up process and the sitting state.

[0054] When it is necessary to judge the motion intention, the control chip 302 obtains the characteristic values ​​obtained by the two inertial measurement units 301 within the analysis window, thereby calculating the mode characteristic value Md and the state characteristic value St at that moment.

[0055] When the characteristic value Md is less than a certain threshold, such as 2, it is judged as the walking and standing stage, otherwise it is judged as the sitting and standing stage.

[0056] During the walking and standing phases, the current state is determined by comparing the characteristic value St with the corresponding thresholds S1 and S2: when St is less than the threshold S1, it is determined to be in the stance phase state; when St is between the thresholds S1 and S2, it is determined to be in the swing phase state; when St is greater than the threshold S2, it is determined to be in the standing state.

[0057] During the sitting and standing up phases, the obtained characteristic value St is compared with the thresholds W1 and W2: when St is less than the threshold W1, it is determined to be in the standing up process state; when St is between the thresholds W1 and W2, it is determined to be in the sitting down process state; when St is greater than the threshold W2, it is determined to be in the sitting state.

[0058] Through the above judgments, the state is obtained and the control is output accordingly.

[0059] Refer to Figure 13 As shown, during the walking and standing phases, when the user is in the above-mentioned swing phase, the unidirectional bending variable stiffness knee joint actuator is in the normal pressure state. The main torsion spring 106 and the auxiliary torsion spring 107 are bent under the action of the inertia of the lower leg. At this time, the actuator does not provide a supporting torque, and the user's leg on this side can move freely.

[0060] When the user is in the above-mentioned stance phase, the unidirectional bending variable stiffness knee joint actuator is in the negative pressure state. The main torsion spring 106 and the auxiliary torsion spring 107 are extended, and the stiffness of the actuator is high. At this time, the actuator provides a supporting torque to prevent the leg from bending.

[0061] When the user is in the above-mentioned standing state, the unidirectional bending variable stiffness knee joint actuator is in the negative pressure state. The main torsion spring 106 and the auxiliary torsion spring 107 are extended, and the stiffness of the actuator is high. At this time, the unidirectional bending variable stiffness knee joint actuator can provide a supporting torque to ensure the user's stable standing.

[0062] During the sitting and standing up phases, when the user is in the above-mentioned sitting down process, the unidirectional bending variable stiffness knee joint actuator is in the normal pressure state. The main torsion spring 106 and the auxiliary torsion spring 107 are bent under the action of gravity. The torsion spring provides a buffering torque and stores energy, thereby buffering the user's sitting down process.

[0063] When the user is in the above-mentioned standing up process, the unidirectional bending variable stiffness knee joint actuator is in the normal pressure state. The main torsion spring 106 and the auxiliary torsion spring 107 release energy and provide a torque to resist gravity, thereby assisting the user's standing up process.

[0064] When the user is in the above-mentioned sitting state, the unidirectional bending variable stiffness knee joint actuator is in the negative pressure state. The torques of the main torsion spring 106 and the auxiliary torsion spring 107 are greatly reduced due to the gear blocking and structural engagement effects. At this time, the energy of the torsion spring does not change, and the effect of the torsion spring on the leg is greatly reduced.

[0065] When the device of the present application is in use, it is fixed to the upper and lower sides of the user's knee joint through two Velcro straps of the fixing device, and two inertial measurement units 301 are respectively fixed to the two Velcro straps 202 using Velcro. The one-way bending variable stiffness knee joint driver is located on the posterior side wall of the knee joint. Among them, the central gear 108 is placed at the center position of the posterior side wall of the knee joint to ensure the clear position of the corresponding joint of the exoskeleton. The control chip 302, the motor driver 303, the lithium battery 304, and the vacuum pump 305 are placed in a satchel around the waist, so as to ensure wearing comfort and reduce the pressure on the knee joint.

[0066] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A flexible wearable knee exoskeleton for assisting the elderly in standing and walking, characterized in that, It includes a unidirectional bending variable stiffness knee joint driver and a motion intention detection and control system; the unidirectional bending variable stiffness knee joint driver includes a vacuum bag with an air pipe joint and a gear set structure arranged in the vacuum bag; the gear set structure includes a central gear and two groups of side gear sets located on both sides of the central gear; each group of side gear sets successively includes an anti-backlash gear, an interlocking gear, a transition gear, and a terminal gear that are meshed with each other; the anti-backlash gear meshes with the central gear, and adjacent gears are connected to each other through a rotating shaft and a connecting rod; an outer engagement sheet layer and an inner engagement sheet layer are respectively arranged on the outer side and the inner side of the bending surface of the gear set structure, and a plurality of spaced engagement teeth that cooperate with the gears of the gear set structure are respectively arranged on the inner sides of the outer engagement sheet layer and the inner engagement sheet layer, and foam glue is filled between adjacent engagement teeth; a torsion spring is installed on the gear set structure, and the torsion spring includes a main torsion spring and a secondary torsion spring, which are used to convert negative work into elastic potential energy for storage and release when needed during the movement of the lower limb; under normal pressure, the main torsion spring and the secondary torsion spring play a buffering role during the bending process and convert mechanical energy into elastic potential energy for storage; when the normal pressure changes to a negative pressure state, the main torsion spring and the secondary torsion spring release energy to provide an auxiliary torque; when the teeth of the anti-backlash gear engage with the limit groove of the central gear to reach the straight state, the stiffness of the unidirectional bending variable stiffness knee joint driver increases to provide a support torque. The motion intention detection and control system includes an inertial measurement unit. During use, it is bound to the user through a fixing device together with the unidirectional bending variable stiffness knee joint driver and is used to obtain the motion data of the thigh and the calf when the user moves; the unidirectional bending variable stiffness knee joint driver is connected to a vacuum pump, and the motion data obtained by the two inertial measurement units are transmitted to a control chip. After the motion intention detection algorithm judges the state by obtaining the characteristic values obtained by the two inertial measurement units within the analysis window, control data is transmitted to the motor driver to control the vacuum pump to pump air or not, so as to accurately control the air pressure in the vacuum bag, thereby controlling the stiffness of the unidirectional bending variable stiffness knee joint driver. Among them, when the motion intention detection and control system makes a motion intention detection and judgment, it judges whether it is the walking and standing stage or the sitting and standing up stage by calculating the mode characteristic value, and judges the state of the walking and standing stage and the state of the sitting and standing up stage by calculating the state characteristic value. Among them, the state of the walking and standing stage is divided into a swing phase, a support phase, and a standing state; the state of the sitting and standing up stage is divided into a sitting process, a standing up process, and a sitting state.

2. The flexible wearable knee exoskeleton for assisting the elderly in standing and walking according to claim 1, characterized in that The main torsion spring and the secondary torsion spring are made of spring steel and are fixed and connected through the rotating shaft.

3. The flexible wearable knee exoskeleton for assisting the elderly in standing and walking according to claim 1, wherein The main torsion spring is installed on the main rotating shaft connected to the shaft hole of the central gear, and the secondary torsion spring is installed on the secondary rotating shaft connected to the shaft hole of the interlocking gear.

4. The flexible wearable knee exoskeleton for assisting the elderly in standing and walking according to claim 1, characterized in that, The vacuum bag is sealed with a thermoplastic polyurethane material.

5. The flexible wearable knee exoskeleton for assisting the elderly in standing and walking according to claim 1, wherein The central gear, anti-backlash gear, interlocking gear, transition gear, and terminal gear are made by 3D printing using a liquid photosensitive resin material.

6. The flexible wearable knee joint exoskeleton for assisting the elderly to stand and walk according to claim 1, wherein The engagement teeth are obtained by 3D printing using a liquid photosensitive resin material.

7. The flexible wearable knee exoskeleton for assisting the elderly in standing and walking according to claim 1, wherein The motor driver is powered by a lithium battery.

8. The flexible wearable knee exoskeleton for assisting the elderly to stand and walk according to claim 1, wherein The unidirectional bending variable stiffness knee joint driver is fixed to the knee joint position of the user through a fixing device.

9. The flexible wearable knee exoskeleton for assisting the elderly in standing and walking according to claim 1, wherein The fixing device includes an outer packaging cloth bag, a magic tape strap fixed to the outer surface of the outer packaging cloth bag, and a metal ring installed on the magic tape strap. The tightness of the unidirectional bending variable stiffness knee joint driver is adjusted by passing the magic tape strap through the metal ring and adjusting the sticking position of the magic tape; one side of the outer packaging cloth bag is open and provided with a zipper for facilitating the taking and placing of the unidirectional bending variable stiffness knee joint driver; the inertial measurement unit is fixed to the magic tape strap.

10. The flexible wearable knee exoskeleton for assisting the elderly to stand and walk according to claim 1, wherein Two central gear tooth grooves are arranged on the circumferential surface of the central gear and are engaged with the central gear limiting teeth of the corresponding two limiting gears. The limiting gear has two limiting gear engaging tooth grooves engaged with the corresponding engaging teeth on both sides and an interlocking gear engaging tooth groove engaged with the limiting gear engaging tooth of the interlocking gear; the interlocking gear has two interlocking gear engaging tooth grooves engaged with the corresponding engaging teeth on both sides and a transition gear engaging tooth groove engaged with the interlocking gear engaging tooth of the transition gear; the end gear has a transition gear engaging tooth engaged with the end gear engaging tooth groove of the transition gear.

Images