A self-adaptive alignment mechanism for a powered exoskeleton human knee joint

Abstract

The application discloses a kind of power-assisted exoskeleton human knee joint adaptive alignment mechanism, based on the mechanism of Schmidt coupling principle, can be automatically adaptive alignment with knee joint rotation center in normal flexion and extension movement of human knee joint, the mechanism of Schmidt coupling principle uses passive three-phase symmetrical multi-link structure, including: for installing the input shaft of motor, for self-alignment intermediate link and the output end connected with knee joint support by power-assisted exoskeleton, and power-assisted exoskeleton human knee joint adaptive alignment mechanism uses three-disc structure, including: input disc, intermediate disc, output disc, each disc is connected by link with bearing, can withstand larger shaft deviation.The application is intrinsically safe and reliable: using passive (passive) design, with intrinsic safety;Avoid the complexity of active scheme, high reliability, suitable for healthy aging scenarios.

Description

Technical Field

[0001] This invention relates to the field of wearable exoskeleton robot technology, specifically an adaptive alignment mechanism for the human knee joint of an assistive exoskeleton. Background Technology

[0002] Existing technologies have the following main problems in providing effective physical support for the human knee joint to perform daily activities:

[0003] Most designs use a fixed single-degree-of-freedom (DoF) articulated structure to simulate knee joint movement, but they cannot precisely align with the knee joint's center of rotation during rotation. This is because the knee joint is a multi-center motion structure, and its center of motion dynamically shifts relative to the exoskeleton as the knee rotates. The trajectory of the instantaneous center of rotation (ICR) of the knee joint is an "inverted J-shape" (e.g., ...). Figure 6 As shown in the figure, the size and specific shape of the trajectory vary from person to person. During the flexion and extension of the knee joint, the J-shaped trajectory mainly manifests as horizontal displacement and small vertical displacement.

[0004] Some mechanical structures attempt to simulate the multi-center motion characteristics of the knee joint through various linkage mechanisms. Although they can match basic dynamic changes, they cannot adjust the instantaneous rotation center or adapt to the different trajectories of different individuals, and the alignment deviation problem still exists.

[0005] Alignment deviations between the instantaneous rotation center of the human knee joint and the rotation center of the exoskeleton can generate unnecessary lateral forces in the knee joint, causing discomfort and pain; prolonged wear may even lead to injury. This discomfort limits the exoskeleton's usability to short periods, severely restricting its practical applications and currently preventing its long-term wear to support daily life.

[0006] As long-wearable exoskeletons designed for healthy aging continue to develop, there is an urgent need for more efficient designs to improve the comfort of wearing exoskeletons and extend their wear time. Summary of the Invention

[0007] The purpose of this invention is to provide an adaptive alignment mechanism for the human knee joint of an exoskeleton, in order to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] An adaptive alignment mechanism for the human knee joint of a assisted exoskeleton, based on the Schmidt coupling principle, can automatically and adaptively align with the center of rotation of the knee joint during normal flexion and extension movements. The Schmidt coupling principle mechanism employs a passive three-phase symmetrical multi-link structure, including: an input shaft for mounting a motor, an intermediate connecting rod for self-alignment, and an output end that connects and supports the assisted exoskeleton to the knee joint. The adaptive alignment mechanism also adopts a three-disc structure, including: an input disc, an intermediate disc, and an output disc, with each disc connected by a bearing-bearing connecting rod, capable of withstanding significant inter-axis misalignment. The three-disc structure comprises an input end, an intermediate section, an output end, a first connecting rod transmission mechanism, a second connecting rod transmission mechanism, a motor, a motor cover, a safety cover, bearings, an exoskeleton thigh section, and an exoskeleton calf section.

[0010] As a further aspect of the present invention: the input end adopts a three-arm symmetrical structure, with a pin assembly integrated at the end of each arm. The pin is inserted into the inner ring of the bearing at one end of the linkage transmission mechanism to form a rotating pair, thereby achieving the hinge connection between the intermediate disk and the first linkage transmission mechanism. Six through holes are provided at the center position, and the motor can be rigidly fixed to the thigh section of the assistive exoskeleton as the power input end of the mechanism by screws.

[0011] As a further aspect of the present invention: the middle section is the core adaptive mechanism for offset compensation and alignment, which also adopts a three-arm symmetrical structure. The three arms are radially distributed, and each arm integrates a pin assembly at its end. The pin pitch circle is consistent with the input disk, and the pin end is provided with a boss structure for bearing positioning. The two ends of the pin extend out of the arm body to form the connection interface between the middle disk and the linkage assembly. The input end pin is inserted into the bearing of the first linkage transmission mechanism, and the output end pin is inserted into the bearing of the second linkage transmission mechanism, both forming a rotating pair, realizing the hinge connection between the middle section and the two sets of linkage mechanisms, and coordinating the movement with the input end and the output end.

[0012] As a further embodiment of the present invention: the output end is the output side of the mechanism, which also adopts a three-arm symmetrical structure. Each arm end integrates a pin assembly. The pin pitch circle is consistent with the input side. Each pin is inserted into the inner ring of the bearing at the two ends of the linkage transmission mechanism to form a rotating pair, thereby realizing the hinge connection between the middle section and the second linkage transmission mechanism. The output end is connected to the exoskeleton leg section to complete the torque transmission path.

[0013] As a further embodiment of the present invention: the first linkage transmission mechanism, as a torque transmission component, is made of three aluminum alloy linkages. Each linkage has an interference fit bearing at both ends and is axially positioned by a snap ring and a shoulder. The instantaneous rotation center trajectory of the vertically arranged knee joint hinge is located 60mm laterally from the midpoint of the knee joint, with a trajectory length of 28mm. Based on this, the linkage length is selected as 14mm, which can provide sufficient offset compensation range for the mechanism. The second linkage transmission mechanism is a torque transmission component with the same structure and specifications as the first linkage transmission mechanism. It adopts the same linkage design and assembly method, forming a closed torque transmission chain with the former.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] 1. Instantaneous rotation center automatically and adaptively aligns with the human knee joint rotation center: Unlike fixed hinge structures (which cannot compensate for offset) or traditional four-bar structures (which only provide fixed offset matching and cannot adapt to individual differences), this design can be personalized within a set range to meet the specific needs of different individuals;

[0016] 2. Intrinsically safe and reliable: It adopts a passive design and has intrinsic safety; it avoids the complexity of active solutions, has high reliability, and is suitable for healthy aging scenarios;

[0017] 3. Lightweight and compact structure: The self-aligning mechanism weighs ≤300g, can support users weighing up to 100kg, and can withstand a torque of 100N·m;

[0018] 4. Simple structure and controllable cost: The mechanism is easy to process and manufacture, suitable for various general-purpose assistive exoskeletons, and has an affordable cost;

[0019] 5. Provides more effective physical support for daily knee joint movements: Traditional four-bar linkages have a theoretical power transmission efficiency of only 85%, and the actual torque transmission efficiency is even lower due to individual differences. The new knee joint mechanism can adapt and maintain alignment, significantly improving torque transmission efficiency. Attached Figure Description

[0020] Figure 1 A front view of the knee joint assembly integrated into the assistive exoskeleton.

[0021] Figure 2 A side view of the knee joint assembly integrated into the assistive exoskeleton.

[0022] Figure 3 Exploded view of the structure of the human knee joint adaptive alignment mechanism for exoskeletons.

[0023] Figure 4 A frontal view of the human body in an exoskeleton-based human knee joint adaptive alignment mechanism.

[0024] Figure 5 A side view of the human body in an exoskeleton-based adaptive alignment mechanism for the human knee joint.

[0025] Figure 6 This is a typical trajectory diagram of the center of rotation of the knee joint under normal movement conditions.

[0026] Figure 7 Detailed diagram of the Schmidt coupling mechanism in the human knee joint adaptive alignment mechanism of the exoskeleton.

[0027] Figure 8 A schematic diagram of the self-alignment drive output shaft principle in the human knee joint adaptive alignment mechanism of the exoskeleton.

[0028] Figure 9 This is a schematic diagram of the motion of the passive mechanism in an exoskeleton.

[0029] In the diagram: 1-Input end, 2-Intermediate section, 3-Output end, 4-Linkage transmission mechanism one, 5-Linkage transmission mechanism two, 6-Motor, 7-Motor cover, 8-Safety cover, 9-Bearing, 10-Exoskeleton thigh section, 11-Exoskeleton lower leg section. Detailed Implementation

[0030] Various exemplary embodiments, features, and aspects of this application will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0031] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0032] Furthermore, to better illustrate this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In some instances, methods, means, and elements well-known to those skilled in the art have not been described in detail in order to highlight the main points of this application.

[0033] Example 1

[0034] Please see Figure 1-9A self-adaptive alignment mechanism for the human knee joint using an assistive exoskeleton, based on the Schmidt coupling principle, can automatically and adaptively align with the knee joint's rotation center during normal knee flexion and extension movements. The mechanism, characterized by its passive three-phase symmetrical multi-link structure, includes: an input shaft for mounting a motor 6, an intermediate link for self-alignment, and an output end connected and supported by the assistive exoskeleton to the knee joint. Details of the mechanism are as follows... Figure 7 As shown: the input end is purple, the output shaft is green, the intermediate connecting rod is yellow, and the connecting rod is black. In this design, the rotation is around the Z-axis, and the alignment deviation between the input shaft and the output shaft occurs in the XY plane. Figure 8 The demonstration showed how the mechanism, when rotating at the input end, compensates for alignment deviations between the input and output axes (X-axis, Y-axis, X+Y-axis) through self-alignment, thereby driving the output shaft. This self-alignment capability lays the foundation for the application of this mechanism in assistive exoskeleton knee joints. Through a combination of translation of the intermediate link and swinging of the connecting link, the mechanism can track and adapt to the dynamic instantaneous rotation center (ICR) of the human knee joint for different individuals. The effective range of self-alignment is twice the length of the connecting link, which provides a basis for link length design. The assistive exoskeleton's self-aligning mechanism for the human knee joint adopts a three-disc structure, including an input disc, a middle disc, and an output disc. These discs are connected by connecting rods with bearings 9, allowing for significant inter-axis misalignment. The three-disc structure comprises an input end 1, a middle section 2, an output end 3, a first connecting rod transmission mechanism 4, a second connecting rod transmission mechanism 5, a motor 6, a motor cover 7, a safety cover 8, bearings 9, an exoskeleton thigh section 10, and an exoskeleton lower leg section 11. The motor 6 is the power source for the mechanism; the motor rotor is connected to the input side center hole, and the motor stator is connected to the assistive exoskeleton thigh section 10. The motor cover 7 protects the motor 6. The safety cover 8 provides protection for the rotating knee joint self-aligning mechanism and provides sufficient clearance to accommodate the mechanism's range of motion. Bearings 9 are installed at both ends of the three transmission connecting rods to ensure smooth power transmission within the mechanism. The exoskeleton thigh section 10 is the thigh portion of the exoskeleton and provides a mounting base for the motor stator. The exoskeleton lower leg segment 11 is the lower leg part of the exoskeleton, which is connected to the motor rotor through a novel self-aligning mechanism.

[0035] Preferably, the input end 1 adopts a three-arm symmetrical structure, with a pin assembly integrated at the end of each arm. The pin is inserted into the inner ring of the bearing 9 at the end of the linkage transmission mechanism 4 to form a rotating pair, thereby realizing the hinge connection between the intermediate disk and the linkage transmission mechanism 4. There are 6 through holes at the center position, and the motor 6 can be rigidly fixed to the thigh section 10 of the assistive exoskeleton as the power input end of the mechanism by screws.

[0036] Preferably, the middle section 2 is the core adaptive mechanism for offset compensation and alignment. It also adopts a three-arm symmetrical structure with the three arms radially distributed. Each arm has a pin assembly integrated at its end. The pin pitch circle is consistent with the input disk. The pin end has a boss structure for positioning the bearing 9. The two ends of the pin extend out of the arm body to form the connection interface between the middle disk and the linkage assembly. The input end pin is inserted into the bearing 9 of the linkage transmission mechanism 1 4, and the output end pin is inserted into the bearing 9 of the linkage transmission mechanism 2 5, both forming a rotating pair to realize the hinge connection between the middle section and the two sets of linkage mechanisms, and to move in coordination with the input end 1 and the output end 3.

[0037] Preferably, the output end 3 is the output side of the mechanism, which also adopts a three-arm symmetrical structure. Each arm end integrates a pin assembly. The pin pitch circle is consistent with the input side. Each pin is inserted into the inner ring of the bearing 9 at the end of the second link transmission mechanism 5 to form a rotating pair, realizing the hinge connection between the middle section and the second link transmission mechanism 5. The output end 3 is connected to the exoskeleton leg section 11 to complete the torque transmission path.

[0038] Preferably, the first linkage transmission mechanism 4 serves as a torque transmission component, consisting of three aluminum alloy linkages. Each linkage has an interference fit bearing 9 at both ends, and is axially positioned using a snap ring and a shoulder. The instantaneous rotation center trajectory of the vertically arranged knee joint hinge is located 60mm laterally from the midpoint of the knee joint, with a trajectory length of 28mm. Based on this, the linkage length is selected as 14mm, which provides sufficient offset compensation range for the mechanism. The second linkage transmission mechanism 5 is also a torque transmission component, with the same structure and specifications as the first linkage transmission mechanism 4. It adopts the same linkage design and assembly method, forming a closed torque transmission chain with the former.

[0039] It should be specifically noted that the self-alignment mechanism unit has a compact structure that can be easily embedded into the knee joint of the assistive exoskeleton and connected to the thigh segment 10 and the lower leg segment 11 of the exoskeleton, and can be driven on demand to support most of the movements required by the human body.

[0040] The adaptive principle of self-alignment mechanisms in motion: To explain the working principle of self-alignment mechanisms. Figure 9 By simplifying the thigh and lower leg components in the diagram, the movement of an imaginary point on the lower leg is shown, highlighting how this point follows the instantaneous rotation center (ICR) curve of the knee joint to maintain alignment during lower leg rotation.

[0041] When the lower leg flexes backward from 0° to 120°, the red reference point on the lower leg always coincides with the J-shaped instantaneous rotation center (ICR) trajectory, indicating that the mechanism can accurately track the instantaneous rotation center of the human knee joint.

[0042] During the movement, the motor drives the input end, and the output end rotates synchronously with the input end. When the human knee joint moves, the middle section performs planar translation, and the three transmission links swing in coordination. This composite motion enables the mechanism to dynamically track the instantaneous rotation center trajectory of the knee joint, ensuring that the exoskeleton's rotation center remains aligned with the center of the human knee joint throughout the entire movement.

[0043] The self-alignment mechanism has a compensation range of twice the length of the three transmission links, with a design margin to accommodate differences in individual anatomical structures and installation tolerances. This mechanism eliminates additional forces and discomfort caused by misalignment, improving the wearing comfort of the assistive exoskeleton and thus expanding its practical application value in everyday life scenarios.

[0044] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0045] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A self-adaptive alignment mechanism for the human knee joint of an assisted exoskeleton, based on the Schmidt coupling principle, which can automatically and adaptively align with the center of rotation of the knee joint during normal flexion and extension movements of the human knee joint, characterized in that... The Schmidt coupling principle mechanism adopts a passive three-phase symmetrical multi-link structure, including: an input shaft for mounting the motor (6), an intermediate link for self-alignment, and an output end that is supported by the connection between the assisted exoskeleton and the knee joint. The assisted exoskeleton human knee joint adaptive alignment mechanism adopts a three-disc structure, including: an input disc, an intermediate disc, and an output disc. The discs are connected by a link with a bearing (9), which can withstand large inter-axis offset. The assisted exoskeleton human knee joint adaptive alignment mechanism adopts a three-disc structure consisting of an input end (1), an intermediate section (2), an output end (3), a link transmission mechanism one (4), a link transmission mechanism two (5), a motor (6), a motor cover (7), a safety cover (8), a bearing (9), an exoskeleton thigh section (10), and an exoskeleton calf section (11).

2. The adaptive alignment mechanism for the human knee joint of the assisted exoskeleton according to claim 1, characterized in that, The input end (1) adopts a three-arm symmetrical structure. Each arm end integrates a pin assembly. The pin is inserted into the inner ring of the bearing (9) at the end of the linkage transmission mechanism (4) to form a rotating pair, realizing the hinge between the intermediate disk and the linkage transmission mechanism (4). There are 6 through holes in the center position, and the motor (6) can be rigidly fixed to the thigh section (10) of the assistive exoskeleton by screws as the power input end of the mechanism.

3. The adaptive alignment mechanism for the human knee joint of the assisted exoskeleton according to claim 1, characterized in that, The middle section (2) is the core adaptive mechanism for offset compensation and alignment. It also adopts a three-arm symmetrical structure with the three arms arranged radially. Each arm has a pin assembly at the end. The pin pitch circle is consistent with the input disk. The pin end has a boss structure for bearing (9) positioning. The two ends of the pin extend out of the arm body to form the connection interface between the middle disk and the linkage assembly. The input end pin is inserted into the bearing (9) of the first linkage transmission mechanism (4), and the output end pin is inserted into the bearing (9) of the second linkage transmission mechanism (5). Both form a rotating pair to realize the hinge between the middle section and the two sets of linkage mechanisms, and move in coordination with the input end (1) and the output end (3).

4. The adaptive alignment mechanism for the human knee joint of the assisted exoskeleton according to claim 1, characterized in that, The output end (3) is the output side of the mechanism. It also adopts a three-arm symmetrical structure. Each arm end integrates a pin assembly. The pin pitch circle is consistent with the input side. Each pin is inserted into the inner ring of the bearing (9) at the end of the second link transmission mechanism (5) to form a rotating pair, realizing the hinge between the middle section and the second link transmission mechanism (5). The output end (3) is connected to the exoskeleton leg section (11) to complete the torque transmission path.

5. The adaptive alignment mechanism for the human knee joint of the assisted exoskeleton according to claim 1, characterized in that, The first link transmission mechanism (4) is a torque transmission component, made of 3 aluminum alloy links. Each link has an interference fit bearing (9) at both ends and is axially positioned by a snap ring and a shoulder. The instantaneous rotation center trajectory of the vertically arranged knee joint hinge is located 60mm laterally from the midpoint of the knee joint, with a trajectory length of 28mm. Based on this, the link length is selected as 14mm, which can provide sufficient offset compensation range for the mechanism. The second link transmission mechanism (5) is a torque transmission component, with the same structure and specifications as the first link transmission mechanism (4). It adopts the same link design and assembly method, forming a closed torque transmission chain with the former.

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