Electric screw drive knee joint for a prosthesis

Abstract

The application discloses a motor-driven screw type knee joint for a prosthesis, which comprises a thigh connecting head, a support and an ankle connecting head, the support is hinged to the thigh connecting head through a support hinge shaft, the thigh connecting head is provided with a swing hinge shaft, the swing hinge shaft is parallel to and spaced from the support hinge shaft, a motor nut is hinged to the swing hinge shaft, a machine box hinge shaft is arranged on the support, the machine box hinge shaft is parallel to the swing hinge shaft, a motor box is hinged to the machine box hinge shaft, a motor is fixedly installed in the motor box, a motor screw is coaxially arranged on an output shaft of the motor, the motor screw is in threaded connection with the motor nut, the motor drives the motor screw to rotate, axial relative displacement is generated between the motor screw and the motor nut, the distance between the swing hinge shaft and the machine box hinge shaft is changed, and the thigh connecting head is driven to perform flexion and extension movement relative to the support around the support hinge shaft. The application provides auxiliary support force for a user and reduces the dependence on active force of a residual limb.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, and in particular relates to an electric screw-type knee joint for prostheses. Background Technology

[0002] Currently, mechanically locking knee joint structures are widely used in lower limb walking aids, braces, and prostheses to ensure sufficient load-bearing capacity and stability of the knee joint during the standing phase. These mechanically locking knee joints typically lock automatically when the knee is extended to prevent accidental knee flexion during walking, thus improving safety. However, when knee flexion is required, users usually need to manually operate the unlocking mechanism to release the lock and restore knee mobility.

[0003] Existing mechanically locked knee joints, due to their mechanical locking mechanism, cannot achieve natural flexion and extension according to the human gait when locked. Users can only maintain a straight leg swing when walking, resulting in a stiff gait. This not only affects walking efficiency but also increases energy consumption. Long-term use can easily lead to compensatory movements of the hip and lower back, reducing walking comfort.

[0004] Furthermore, existing mechanical knee locks require users to manually unlock them before performing actions such as going up and down stairs, going up and down slopes, crossing obstacles, sitting down, and standing up. This process is cumbersome and inconvenient. If users forget to unlock or do not unlock in time, it may also affect the continuity of movement and the user experience, reducing the practicality of the assistive device.

[0005] Therefore, existing technologies have at least the following problems: mechanically locked knee joints can only maintain straight-leg walking when locked, and cannot achieve a natural knee-flexed gait; knee-flexion movements rely on manual unlocking, which is cumbersome; and they are not convenient for daily activities such as going up and down stairs, going up and down slopes, and sitting down, making it difficult to meet users' needs for natural, safe, and continuous walking. Since hydraulic and pneumatic knee joints are passive control mechanisms, they can only adjust the damping according to external loads and cannot actively generate driving force, thus failing to provide users with active knee extension assistance. Summary of the Invention

[0006] This invention provides an electrically powered screw-type knee joint for prostheses to solve existing technical problems.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows: An electric screw-type knee joint for prostheses includes a thigh connector, a support, and an ankle connector located at the lower end of the support. The support is hinged to the thigh connector via a support hinge shaft. The thigh connector has a swing hinge shaft, which is parallel to and spaced apart from the support hinge shaft. A motor nut is hinged to the swing hinge shaft. The support has a housing hinge shaft, which is parallel to the swing hinge shaft. A motor housing is hinged to the housing hinge shaft, and a motor is fixedly installed in the motor housing. The output shaft of the motor is connected to a coaxially arranged motor screw. The motor screw and the motor nut are threaded together. The motor drives the motor screw to rotate, causing axial relative displacement between the motor screw and the motor nut, thereby changing the distance between the swing hinge shaft and the housing hinge shaft, and thus driving the thigh connector to perform flexion and extension movements relative to the support around the support hinge shaft.

[0008] As a further improvement to the above technical solution: The bracket includes two side plates spaced apart from each other. The upper parts of the two side plates are respectively mounted to both ends of the bracket hinge shaft by bearings, and the middle parts are respectively mounted to both ends of the housing hinge shaft by bearings.

[0009] The motor box has a square prism structure and is sandwiched between two side plates.

[0010] The two side walls of the motor box are respectively attached to the inner side of the corresponding side plate.

[0011] The bracket is equipped with a battery compartment, which contains a battery that is electrically connected to the motor.

[0012] The battery compartment is located at the lower part of the bracket.

[0013] The battery compartment is formed by two side panels and a partition plate connecting the two side panels.

[0014] The motor nut is connected to a sleeve, which is hinged to the thigh connector via a swing hinge shaft.

[0015] It also includes a control system, which includes a first angle sensor, a second angle sensor, and a controller. The first angle sensor is located at the hinge axis of the support and is used to detect the relative rotation angle between the thigh connector and the support. The second angle sensor is located between the prosthesis socket and the wearer's torso and is used to detect the relative posture angle of the prosthesis socket relative to the wearer's torso. The controller is electrically connected to the first angle sensor, the second angle sensor, and the motor. The controller determines the wearer's movement state based on the detection signals from the first angle sensor and the second angle sensor and controls the motor to drive the motor screw to rotate in order to adjust the flexion and extension movement of the knee joint.

[0016] The controller identifies the current gait state based on the knee flexion and extension angles and their changes detected by the first angle sensor, and determines the wearer's movement intention by combining the relative posture angle of the prosthesis socket with the wearer's torso detected by the second angle sensor. Based on the gait state and movement intention, the controller controls the output torque of the motor so that the motor screw-type knee joint provides corresponding flexion and extension assistance force.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: Compared to existing mechanically locked knee joints, this design allows for knee flexion and extension without manual unlocking, enabling the prosthesis to achieve natural knee flexion and walking, thus improving the continuity and comfort of walking. Furthermore, compared to hydraulic or pneumatic knee joints, this design actively outputs knee extension power, providing auxiliary support for the user during actions requiring active knee extension, such as standing, climbing stairs, and going uphill. This reduces reliance on active force exertion from the residual limb, lowers energy consumption, and improves the ease of use and naturalness of gait. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of an electric screw-type knee joint used in prostheses. Figure 1 ; Figure 2 This is a schematic diagram of the structure of an electric screw-type knee joint used in prostheses. Figure 2 .

[0020] Legend: 1. Thigh connector; 11. Swing hinge shaft; 12. Motor nut; 2. Bracket; 21. Machine box hinge shaft; 22. Motor box; 23. Motor; 24. Motor screw; 25. Side plate; 26. Bearing; 27. Isolation plate; 3. Ankle connector; 4. Bracket hinge shaft; 5. Battery compartment; 6. Sleeve. Detailed Implementation

[0021] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0022] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0023] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0024] Example: Figure 1 and Figure 2 As shown, the electric screw-type knee joint for prostheses in this embodiment includes a thigh connector 1, a bracket 2, and an ankle connector 3 located at the lower end of the bracket 2. The bracket 2 is hinged to the thigh connector 1 via a bracket hinge shaft 4. The thigh connector 1 is provided with a swing hinge shaft 11, which is parallel to and spaced apart from the bracket hinge shaft 4. A motor nut 12 is hinged to the swing hinge shaft 11. The bracket 2 is provided with a housing hinge shaft 21, which is parallel to the swing hinge shaft 11. A motor housing 22 is hinged to the connecting shaft 21, and a motor 23 is fixedly installed in the motor housing 22. The output shaft of the motor 23 is connected to a coaxially arranged motor screw 24. The motor screw 24 is threadedly engaged with the motor nut 12. The motor 23 drives the motor screw 24 to rotate, causing an axial relative displacement between the motor screw 24 and the motor nut 12. This changes the distance between the swing hinge shaft 11 and the hinge shaft 21 of the housing, thereby driving the thigh connector 1 to flex and extend relative to the bracket 2 around the bracket hinge shaft 4. Compared with existing knee joints using mechanical locking structures, this embodiment eliminates the need for the user to manually release the lock before flexing the knee, allowing the prosthesis to achieve continuous and natural flexion and extension movements according to usage needs. This avoids the gait stiffness caused by only being able to swing the leg straight, improving the naturalness, comfort, and continuity of walking. Furthermore, during actions requiring knee flexion, such as going up and down stairs, going down slopes, crossing obstacles, sitting down, and standing up, no manual unlocking is required, simplifying the usage process and improving the convenience and efficiency of daily activities. Furthermore, compared to hydraulic or pneumatic knee joints that primarily rely on hydraulic or pneumatic damping for passive cushioning and resistance adjustment and cannot actively output driving force, this prosthesis uses a motor 23 to drive a motor screw 24 for lead screw transmission. This allows for the active output of knee joint extension power, providing active assistance to the user during actions requiring active knee extension, such as standing, climbing stairs, and going uphill. This reduces the user's reliance on the residual limb and other parts of the body for driving force, thus lowering physical exertion and exercise burden. Simultaneously, the lead screw transmission features high transmission efficiency, smooth movement, high positioning accuracy, and large output torque, enabling stable control of the knee joint flexion and extension angles. This makes the prosthesis movements smoother and more reliable, improving the overall user experience and the adaptability of the prosthesis.

[0025] In this embodiment, the bracket 2 includes two side plates 25 spaced apart from each other. The upper parts of the two side plates 25 are respectively mounted to both ends of the bracket hinge shaft 4 via bearings 25, and the middle parts are respectively mounted to both ends of the housing hinge shaft 21 via bearings 25. The two side plates 25 form a frame-type support structure, which can provide end support for the bracket hinge shaft 4 and the housing hinge shaft 21, respectively, thereby improving the installation stability of each rotating component. At the same time, the connection via bearings 25 can reduce rotational friction resistance, improve the rotational flexibility of each hinge part, reduce wear, and improve the smoothness and service life of the knee joint.

[0026] In this embodiment, the motor box 22 has a quadrangular prism structure and is clamped between two side plates 25. The quadrangular prism structure facilitates the installation and fixation of the motor 23 and related transmission components. Furthermore, the clamping of the motor box 22 between the two side plates 25 makes full use of the internal space of the bracket 2, making the overall structure more compact, which helps to reduce the overall volume and improve the structural integration.

[0027] In this embodiment, the two side walls of the motor box 22 are respectively abutted against the inner side surfaces of the corresponding side plates 25. By abutting the motor box 22 against the two side plates 25, the installation stability of the motor box 22 can be further improved, its lateral sway can be limited, the overall structural rigidity can be enhanced, and the transmission of the motor screw 24 driven by the motor 23 can be more stable and reliable.

[0028] In this embodiment, the bracket 2 is provided with a battery compartment 5, which contains a battery electrically connected to the motor 23. By placing the battery inside the bracket 2, the motor 23 can be directly powered without the need for an external power supply device. This allows the electric screw-type knee joint to form an integrated structure, improving ease of use and protecting the battery by reducing the risk of damage from external impacts.

[0029] In this embodiment, the battery compartment 5 is located at the lower part of the support 2. Placing the battery compartment 5 at the lower part of the support 2 makes full use of the internal space of the support 2, making the overall structural layout more reasonable; at the same time, it helps to lower the overall center of gravity of the knee joint, improve the stability after wearing, reduce the moment of inertia, and make the movement of the prosthesis more stable and natural.

[0030] In this embodiment, the battery compartment 5 is formed by two side plates 25 and an isolation plate 27 connecting the two side plates 25. By using the side plates 25 and the isolation plate 27 to form the battery compartment 5, a battery installation space can be formed without adding a separate shell, which simplifies the overall structure and improves the space utilization. At the same time, the isolation plate 27 can also limit and protect the battery, improving the stability of battery installation.

[0031] In this embodiment, the motor nut 12 is connected to a sleeve 6, which is hinged to the thigh connector 1 via a swing hinge shaft 11. The sleeve 6 serves as the connection structure between the motor nut 12 and the swing hinge shaft 11, improving the connection strength and installation reliability. Simultaneously, it allows the motor nut 12 to swing smoothly around the swing hinge shaft 11, adapting to the angular changes between the motor screw 24 and the motor nut 12 during transmission, avoiding additional stress, and improving the smoothness and reliability of the screw drive.

[0032] This embodiment also includes a control system, which comprises a first angle sensor, a second angle sensor, and a controller. The first angle sensor is located at the hinge shaft 4 of the support frame and is used to detect the relative rotation angle between the thigh connector 1 and the support frame 2. The second angle sensor is located between the prosthesis socket and the wearer's torso and is used to detect the relative posture angle of the prosthesis socket relative to the wearer's torso. The controller is electrically connected to the first angle sensor, the second angle sensor, and the motor 23. The controller determines the wearer's motion state based on the detection signals from the first and second angle sensors and controls the motor 23 to drive the motor screw 24 to rotate, thereby adjusting the knee joint flexion and extension movements. By setting the first and second angle sensors, important parameters reflecting the wearer's motion state can be obtained using only the knee joint flexion and extension angle information and the posture information of the prosthesis socket relative to the wearer's torso. This eliminates the need for additional detection elements such as plantar pressure sensors and force sensors, reducing the number of sensors, simplifying the control system structure, lowering manufacturing costs, and improving system reliability. Meanwhile, the second angle sensor can detect the relative posture changes between the wearer's torso and the prosthesis socket. Compared with the control method that only detects the knee joint angle, it can more accurately perceive the wearer's body tilt trend and movement changes, providing more effective information for subsequent movement status judgment and active assistance control, and improving the prosthesis's response time and adaptability to the wearer's movement needs.

[0033] In this embodiment, the controller identifies the current gait state based on the knee flexion and extension angles and their changes detected by the first angle sensor, and determines the wearer's movement intention by combining the relative posture angle of the prosthesis socket with the wearer's torso detected by the second angle sensor. Based on the gait state and movement intention, the controller controls the output torque of motor 23 to provide corresponding flexion and extension assistance force to the motor screw-type knee joint. By combining knee joint angle change information with torso posture information, the controller can comprehensively judge the wearer's current movement stage and trend, such as identifying different gait states like the support stage, swing stage, heel-to-ground stage, and toe-off stage. It also judges the wearer's movement intention based on torso leaning forward or backward, thereby adjusting the output torque of motor 23 in advance. During movements requiring active assistance, such as leg lifting, standing up, climbing stairs, or going uphill during the swing stage, the controller can control motor 23 to output corresponding assistance force, driving the motor screw 24 to move and achieve active knee flexion and extension assistance. During normal walking, it can adjust the knee joint movement state according to gait changes, making the prosthesis movement smoother and more natural.

[0034] Compared to existing intelligent prosthetic control methods that rely on the fusion of multiple sensors to obtain motion information, this embodiment uses dual-angle sensing information to achieve gait recognition and motion intent judgment. This reduces the number of sensors and the complexity of signal fusion, decreases the system's computational burden and power consumption, and improves the real-time performance and stability of the prosthetic control system. Furthermore, by combining the controller with an electric screw-type knee joint actuator, the prosthesis can not only achieve passive follow-up adjustment but also actively output auxiliary power according to the wearer's movement needs, improving the naturalness, continuity, and comfort of walking.

[0035] In this embodiment, the control method includes the following steps: First, the controller acquires the knee flexion-extension angle value θ1 detected by the first angle sensor and the relative posture angle θ2 of the prosthesis socket relative to the wearer's torso detected by the second angle sensor.

[0036] Among them, the knee flexion-extension angle θ1 is used to reflect the relative motion state between the thigh connector 1 and the bracket 2, and can characterize the current degree of flexion-extension and the trend of motion change of the prosthesis knee joint; the relative posture angle θ2 is used to reflect the changes in the wearer's body posture, and can characterize the tilting trend of the wearer's trunk relative to the prosthesis socket.

[0037] Subsequently, the controller identifies the wearer's current gait state based on the knee flexion-extension angle value θ1 and its changing trend. Specifically, the controller can determine whether the wearer is currently in different movement stages, such as the support phase, swing phase, heel-to-ground phase, or toe-off phase, based on changes in the knee joint angle.

[0038] Simultaneously, the controller determines the wearer's current movement intention based on the relative posture angle θ2. Specifically, the controller can determine whether the wearer has a need for forward acceleration, backward deceleration, climbing stairs, or other movements based on the posture changes of the wearer's torso relative to the prosthesis socket.

[0039] Finally, the controller controls the motor 23 to output the corresponding driving force according to the identified gait state and movement intention, so that the motor 23 drives the motor screw 24 to rotate, thereby realizing the adjustment of knee flexion and extension movements.

[0040] During movements requiring active assistance, such as leg lifting during the swing phase, standing up, climbing stairs, or going uphill, the controller controls the motor 23 to output auxiliary power, causing the motor screw 24 to drive the motor nut 12 to move, thereby providing assistance for knee flexion and extension and reducing the wearer's need for active force exertion of the residual limb; during normal walking, the controller adjusts the output of the motor 23 in real time according to changes in gait, making knee joint movement more stable and natural.

[0041] In this embodiment, by combining dual-angle sensing control with an electric screw-type knee joint, the prosthesis can actively adjust knee joint movements according to the wearer's current movement state and intentions. Compared to existing mechanical locking knee joints that can only maintain a fixed locked state and cannot achieve continuous knee flexion, and hydraulic or pneumatic knee joints that mainly rely on passive damping adjustment and cannot actively output auxiliary power, this embodiment can actively provide knee flexion and extension assistance, improving the continuity, naturalness, and comfort of the prosthesis during walking.

[0042] Meanwhile, because the second angle sensor can detect changes in the wearer's torso posture in advance, the controller can more timely judge the movement trend and adjust the motor output, improving the prosthesis control response speed and making the prosthesis movement more in line with the natural gait characteristics of the human body.

Claims

1. A power screw-type knee joint for a prosthesis, comprising a thigh connector (1), a support (2), and an ankle connector (3) located at the lower end of the support (2), wherein the support (2) is hinged to the thigh connector (1) via a support hinge shaft (4), characterized in that, The thigh connector (1) is provided with a swing hinge shaft (11), which is parallel to and spaced apart from the bracket hinge shaft (4). A motor nut (12) is hinged on the swing hinge shaft (11). The bracket (2) is provided with a housing hinge shaft (21), which is parallel to the swing hinge shaft (11). A motor housing (22) is hinged on the housing hinge shaft (21), and a motor (23) is fixedly installed in the motor housing (22). The output shaft of the motor (23) is connected to a coaxially arranged motor screw (24). The motor screw (24) is threadedly engaged with the motor nut (12). The motor (23) drives the motor screw (24) to rotate, causing an axial relative displacement between the motor screw (24) and the motor nut (12), thereby changing the distance between the swing hinge shaft (11) and the machine box hinge shaft (21), thereby driving the thigh connector (1) to flex and extend relative to the bracket (2) around the bracket hinge shaft (4).

2. The electrically driven screw-type knee joint for prostheses according to claim 1, characterized in that, The bracket (2) includes two side plates (25) spaced apart from each other. The upper parts of the two side plates (25) are respectively mounted on both ends of the bracket hinge shaft (4) by bearings (26), and the middle parts are respectively mounted on both ends of the housing hinge shaft (21) by bearings (26).

3. The electrically driven screw-type knee joint for prostheses according to claim 2, characterized in that, The motor box (22) has a quadrangular prism structure and is sandwiched between two side plates (25).

4. The electrically driven screw-type knee joint for prostheses according to claim 3, characterized in that, The two side walls of the motor box (22) are respectively attached to the inner side of the corresponding side plate (25).

5. The electrically driven screw-type knee joint for prostheses according to claim 1, characterized in that, The bracket (2) is provided with a battery compartment (5), and the battery compartment (5) contains a battery that is electrically connected to the motor (23).

6. The electrically driven screw-type knee joint for prostheses according to claim 5, characterized in that, The battery compartment (5) is located at the lower part of the bracket (2).

7. The electrically driven screw-type knee joint for prostheses according to claim 6, characterized in that, The battery compartment (5) is formed by two side panels (25) and an isolation plate (27) connecting the two side panels (25).

8. The electrically driven screw-type knee joint for prostheses according to claim 1, characterized in that, The motor nut (12) is connected to a sleeve (6), which is hinged to the thigh connector (1) via a swing hinge shaft (11).

9. The electrically driven screw-type knee joint for prostheses according to any one of claims 1-8, characterized in that, It also includes a control system, which includes a first angle sensor, a second angle sensor and a controller. The first angle sensor is located at the hinge shaft (4) of the bracket and is used to detect the relative rotation angle between the thigh connector (1) and the bracket (2). The second angle sensor is located between the prosthesis socket and the wearer's torso and is used to detect the relative posture angle of the prosthesis socket relative to the wearer's torso. The controller is electrically connected to the first angle sensor, the second angle sensor and the motor (23) respectively. The controller determines the wearer's movement state based on the detection signals of the first angle sensor and the second angle sensor and controls the motor (23) to drive the motor screw (24) to rotate in order to adjust the knee joint flexion and extension movement.

10. The electrically driven screw-type knee joint for prostheses according to claim 9, characterized in that, The controller identifies the current gait state based on the knee flexion and extension angles and their changes detected by the first angle sensor, and determines the wearer's movement intention by combining the relative posture angle of the prosthesis socket with the wearer's torso detected by the second angle sensor. Based on the gait state and movement intention, the controller controls the output torque of the motor (23) so that the motor screw knee joint provides corresponding flexion and extension assistance force.

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