Three-degree-of-freedom ankle prosthesis with gear mechanism

Abstract

The application discloses a three-degree-of-freedom ankle prosthesis with a gear mechanism. The three-degree-of-freedom ankle prosthesis with the gear mechanism comprises a prosthesis sleeve, a driving device assembly arranged in and connected with the prosthesis sleeve, a gear motion assembly arranged in the prosthesis sleeve and engaged with the driving device assembly, and a magnetic damping connecting device with one end connected with the prosthesis sleeve. A prosthesis foot is connected with the other end of the magnetic damping connecting device. The driving device assembly is used for driving the gear motion assembly to move, so that the three-degree-of-freedom ankle prosthesis with the gear mechanism has three active degrees of freedom. The magnetic damping connecting device provides different damping forces by changing the current size, and is used for supporting and keeping balance. Through cooperation of the driving device assembly, the gear motion assembly and the magnetic damping connecting device, the three active degrees of freedom can be realized, so that the motion controllability and compliance of the prosthesis system are improved.

Description

Technical Field

[0001] The present application relates to the technical field of prosthetic limbs, and in particular to a three-degree-of-freedom ankle joint prosthesis with a gear mechanism. Background Art

[0002] Currently, ankle prostheses on the market mostly have a single active degree of freedom in the sagittal plane and two active degrees of freedom in the sagittal and coronal planes. Usually, the internal rotation and external rotation degrees of freedom in the horizontal plane are used as passive degrees of freedom or fixed. Internal and external rotation of the ankle joint are essential for maintaining proper gait, balance and functional activities. For example, when walking, internal rotation enables the foot to adapt to uneven ground. During weight-bearing activities, external rotation helps stabilize the ankle. Therefore, compared with the natural ankle joint, the range of motion of the ankle prostheses currently on the market is limited, and they cannot adapt to complex terrain and changing gaits. Due to the lack of freedom of the ankle prosthesis, it will also cause instability when the patient walks or performs other exercises, increase the risk of the patient falling, and pose a safety hazard.

[0003] The rigid structure of the prosthesis makes patients more prone to fatigue, especially when walking or standing for long periods of time.

[0004] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned deficiencies of the prior art.

[0005] Application Contents

[0006] The purpose of the present application is to provide a three-degree-of-freedom ankle prosthesis with a gear mechanism to overcome or at least alleviate at least one of the above-mentioned defects of the prior art.

[0007] To achieve the above objectives, the present application provides a three-degree-of-freedom ankle prosthesis with a gear mechanism, wherein the three-degree-of-freedom ankle prosthesis with a gear mechanism comprises:

[0008] prosthetic sleeves;

[0009] a drive assembly disposed within the prosthetic sleeve and connected to the prosthetic sleeve;

[0010] a gear motion assembly, the gear motion assembly being disposed within the prosthetic sleeve and meshing with the drive assembly;

[0011] a magnetic damping connection device, one end of which is connected to the prosthetic sleeve;

[0012] A prosthetic foot connected to the other end of the magnetic damping connection device; wherein,

[0013] The driving device assembly is used to drive the gear motion assembly to move, so that the three-degree-of-freedom ankle joint prosthesis with the gear mechanism has three active degrees of freedom of movement;

[0014] The magnetic damping connection device is used to provide different damping forces by changing the current size, and achieve motion matching with the gear motion component through logical control, thereby providing variable support force to the three-degree-of-freedom ankle joint prosthesis with a gear mechanism.

[0015] Optionally, there are two drive device assemblies, each of which includes:

[0016] a driving device body connected to the prosthetic sleeve;

[0017] A special-shaped gear is connected to the driving device body and is engaged with the gear motion assembly.

[0018] Optionally, the driving device body includes a motor assembly, a small helical gear, a large helical gear, an inner worm gear, a small gear, a connecting shaft, a bearing, a small support rod, a support shaft, and a support seat; wherein,

[0019] The motor assembly is connected to the prosthetic sleeve;

[0020] The output shaft of the motor assembly is connected to the small helical gear;

[0021] The small helical gear meshes with the large helical gear;

[0022] The supporting shaft is threadedly connected to the connecting shaft;

[0023] The special-shaped gear is arranged on the connecting shaft and can rotate around the connecting shaft;

[0024] The bearing is installed inside the special-shaped gear;

[0025] The support shaft is threadedly connected to the tail end of the small support rod;

[0026] The front section of the inner worm gear meshes with the pinion;

[0027] The small diameter section of the support shaft is used to support the large helical gear;

[0028] The supporting shaft is connected to the prosthesis sleeve through a supporting seat.

[0029] Optionally, the gear motion assembly includes a spherical gear and an output rod, wherein the cross section of the spherical gear is the profile of an involute gear, the gear module is 2, and the number of teeth is 22; one end of the output rod is connected to the spherical gear, and the other end is connected to the prosthetic foot;

[0030] The cross section of the special-shaped gear for meshing with the spherical gear is the profile of an involute gear, the gear module is 2, the number of gear teeth is 11, which is the same as the cross-sectional gear profile module of the spherical gear, the tooth profile angle is equal, and the transmission ratio is 2:1.

[0031] Optionally, the prosthetic foot comprises:

[0032] A tray, wherein the magnetic damping connection device is provided on one surface of the tray; and the output rod is connected to the tray;

[0033] a keel connected to the other surface of the tray;

[0034] An elastic foot blade connected to the keel;

[0035] A lower blade is connected to the keel.

[0036] The prosthetic foot further comprises:

[0037] A plantar pressure sensor is provided on the contact portion between the elastic foot blade and the ground.

[0038] Optionally, a receiving groove is provided on the keel;

[0039] an inertial measurement unit, the inertial measurement unit being disposed in the accommodating groove;

[0040] A gyroscope is arranged at the rear end surface of the keel.

[0041] Optionally, a through hole is provided below the prosthetic sleeve;

[0042] The bottom end plane of the prosthetic sleeve is threadedly connected to six connecting posts;

[0043] The internal thread of the connecting column is connected to the thread of the ball seat, and the ball seat is hinged to the ball head rod.

[0044] Optionally, the magnetic damping connection device includes a magnetic conductive layer, a steel cylinder, a magnetic base, a spiral coil, a linear bearing, a conductor layer, a ball head rod, a ball head cover, a ball seat, and a connecting column; wherein,

[0045] The magnetic conductive layer is threadedly connected to the inner wall of the steel cylinder, the magnetic base is threadedly connected to the inner wall of the steel cylinder, the spiral coil is stuck in the groove of the magnetic base, the two ends of the magnetic base are gaskets and linear bearings, the conductor layer is threadedly connected to the ball head rod, and the ball head rod drives the conductor layer to move in the steel cylinder; the right end of the steel cylinder is screwed to the ball head cover, the ball head of the ball head cover is hinged to the ball seat, and the ball seat is threadedly connected to the tray through a connecting column.

[0046] Optionally, the two special-shaped gears are distributed inside the prosthesis sleeve at an angle of 60° to each other, and the meshing planes of the two special-shaped gears and the ball gear are also correspondingly at an angle of 60°.

[0047] The three-degree-of-freedom ankle prosthesis with a gear mechanism of the present application can achieve three-degree-of-freedom movement through the cooperation of the drive device assembly and the gear motion assembly. The three-degree-of-freedom ankle prosthesis can improve the motion controllability and motion flexibility of the prosthetic system through independent and coupled control of the three degrees of freedom of the ankle joint, improve the flexibility of the prosthetic system, improve the adaptability to different terrains and gaits, and improve the quality of life of amputees. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 4 is a system schematic diagram of a three-degree-of-freedom ankle prosthesis with a gear mechanism according to an embodiment of the present application.

[0049] Figure 2 yes Figure 1 The diagram shows the structure of the special-shaped gears and ball gears in the three-degree-of-freedom ankle joint prosthesis with a gear mechanism.

[0050] Figure 3 yes Figure 1 The internal structure diagram of the drive device in the three-degree-of-freedom ankle joint prosthesis with a gear mechanism is shown.

[0051] Figure 4 yes Figure 1 The internal structure diagram of the magnetic damper in the three-degree-of-freedom ankle prosthesis with a gear mechanism is shown.

[0052] Figure 5 yes Figure 1 The structure diagram of the prosthetic foot in a three-degree-of-freedom ankle prosthesis with a gear mechanism is shown.

[0053] Figure 6 yes Figure 1 Schematic diagram of the movement of a single special-shaped gear and a ball gear in a three-degree-of-freedom ankle joint prosthesis with a gear mechanism.

[0054] Figure 7 yes Figure 1 Schematic diagram of the kinematic joint of two special-shaped gears and a ball gear in a three-degree-of-freedom ankle joint prosthesis with a gear mechanism.

[0055] Figure 8 yes Figure 1 The diagram shown is a diagram of the equivalent connecting rod model of the special-shaped gear and ball gear of the three-degree-of-freedom ankle joint prosthesis with a gear mechanism.

[0056] Figure 9 yes Figure 1 Schematic diagram of the forward kinematics model of two special-shaped gears and a ball gear in a three-degree-of-freedom ankle joint prosthesis with a gear mechanism.

[0057] Figure 10 yes Figure 1 The equivalent model diagram of the ankle joint with a damper is shown.

[0058] Figure 11 yes Figure 1 Schematic diagram of the ankle joint damper posture.

[0059] Figure 12 yes Figure 1 The plan view of the hinge position of the dynamic platform of the ankle joint damper is shown.

[0060] Figure 13 yes Figure 1 The diagram shows a plan view of the hinge point position of the ankle joint damper fixed platform.

[0061] Figure 14 yes Figure 1 The overall internal structure diagram of the three-degree-of-freedom ankle prosthesis with a gear mechanism is shown.

[0062] Reference numerals

[0063] 1 ball gear 2 Special-shaped gears 3 motor 4 Small helical gear 5 Large helical gear 6 Support shaft 7 Internal worm gear 8 connecting shaft 9 bearings 10 gasket 11 Small gear 12 Small support rod 13 Support seat 14 Prosthetic sleeve 15 Connecting column 16 tee 17 club head 18 Magnetic layer 19 steel cylinder 20 Magnetic base 21 Linear bearings 22 Conductor layer 23 ball head cover 24 Prosthetic foot 25 tray 26 keel 27 Elastic foot blades 28 Elastic foot blades 29 Solenoid 30 Top shoulder 31 stopper 32 Stepped gasket 33 Motor support 34 Drive device 35 Magnetic damper 36 Inertial Measurement Unit 37 gyroscope 38 output rod 39 Plantar pressure sensor 101 Driver module DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be understood as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0065] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as limiting the scope of protection of this application.

[0066] like Figures 1 to 7The three-degree-of-freedom ankle prosthesis with a gear mechanism shown includes a prosthetic sleeve, a drive assembly, a gear motion assembly, a magnetic damping connection device, and a prosthetic foot, wherein:

[0067] The drive device assembly is disposed in the prosthetic sleeve and connected to the prosthetic sleeve;

[0068] A gear motion assembly is disposed within the prosthetic sleeve, and the gear motion assembly is engaged with the drive device assembly;

[0069] One end of the magnetic damping connection device is connected to the prosthetic sleeve;

[0070] The prosthetic foot is connected to the other end of the magnetic damping connection device; wherein,

[0071] The driving device assembly is used to drive the gear motion assembly to move, so that the three-degree-of-freedom ankle joint prosthesis with the gear mechanism has three active degrees of freedom of movement;

[0072] The magnetic damping connection device is used to provide different damping forces by changing the current size, and achieve motion matching with the gear motion component through logical control, thereby providing variable support force to the three-degree-of-freedom ankle joint prosthesis with a gear mechanism.

[0073] The three-degree-of-freedom ankle prosthesis with a gear mechanism of the present application can achieve three-degree-of-freedom movement through the cooperation of the drive device assembly and the gear motion assembly. The three-degree-of-freedom ankle prosthesis can improve the motion controllability and motion flexibility of the prosthetic system through independent and coupled control of the three degrees of freedom of the ankle joint, improve the adaptability to different terrains and gaits, and improve the quality of life of amputees.

[0074] In this embodiment, the three degrees of freedom of movement are plantar flexion / dorsiflexion in the sagittal plane, inversion / eversion in the coronal plane, and internal rotation / external rotation in the horizontal plane.

[0075] In this embodiment, there are two drive device assemblies, each of which includes a drive device body and a special-shaped gear 2. The drive device body is connected to the prosthetic sleeve; the special-shaped gear is connected to the drive device body, and the special-shaped gear is engaged with the gear motion assembly.

[0076] In this embodiment, the driving device body includes a motor assembly 3, a small bevel gear 4, a large bevel gear 5, an inner worm gear 7, a small gear 11, a connecting shaft 8, a bearing 9, a small support rod 12, a support shaft 6, and a support seat 13; wherein, the motor assembly 3 is connected to the prosthetic sleeve 14; the output shaft of the motor assembly 3 is connected to the small bevel gear 4; the small bevel gear 4 is meshed with the large bevel gear 5; the support shaft 6 is threadedly connected to the connecting shaft 8; the special-shaped gear 2 is arranged on the connecting shaft 8 and can rotate around the fixed axis of the connecting shaft 8; the bearing 9 is installed inside the special-shaped gear 2; the support shaft 6 is threadedly connected to the tail end of the small support rod 12; the front section of the inner worm gear 7 is meshed with the small gear 11; wherein, the small shaft diameter section of the support shaft 6 is used to support the large bevel gear 5; the support shaft 6 is connected to the prosthetic sleeve 14 through the support seat 13.

[0077] More specifically, see Figure 3 and Figure 12 The motor 3 is connected to the threaded hole of the prosthetic sleeve 14 through the motor support seat 33. The output shaft of the motor 3 is directly connected to the small bevel gear 4. The normal module of the small bevel gear 4 and the large bevel gear 5 is 1.5, the normal pressure angle is 20°, the spiral angles are equal in size and opposite in direction, and the meshing conditions are met. The large diameter section of the support shaft 6 is slotted and the two side planes are milled. It is threadedly connected to the connecting shaft 8. The special-shaped gear 2 can rotate around the connecting shaft 8. The bearing 9 is installed inside the special-shaped gear 2 and is positioned by the top shoulder 30 and the gasket 10. The bearing 9 can reduce the friction between the special-shaped gear 2 and the connecting shaft when it is meshed and rotated. The slot in the middle diameter section of the support shaft 6 leaves enough room for the small gear 11 to move. There is a positioning hole at the bottom end of the slot, which is threadedly connected to the tail end of the small support rod 12. The small support rod 12 passes through the center hole of the small gear 11 to ensure the position accuracy of the small gear 11. The front section of the inner worm gear 7 is developed into a spiral internal tooth surface, forming a meshing motion relationship with the small gear 11. The rear section of the inner worm gear 7 is provided with a through hole, which is interference fit with the middle diameter section of the support shaft 6. When the small gear 11 meshes and rotates with the inner worm gear 7, the inner worm gear 7 can rotate around the fixed axis of the support shaft 6. The small diameter section of the support shaft 6 is used to support the large helical gear 5. There is a block 31 between the two large helical gears 5 to ensure the movement space of the two small helical gears 4. The large helical gear 5 that rotates around the fixed axis of the support shaft has a bearing inside. The stepped gasket 32 ​​can reduce the friction between the large helical gear 5 and the block 31 and the support shaft 6, and can also serve as a top shoulder of the bearing. Another large helical gear 5 is fixedly connected to the support shaft 6 and rotates together. The support shaft 6 is connected to the through-hole bolt on the prosthetic sleeve 14 through the support seat 13.

[0078] In this embodiment, the gear motion assembly includes a spherical gear 1 and an output rod 38. The cross-section of the spherical gear is the profile of an involute gear, the gear module is 2, and the number of teeth is 22. One end of the output rod 38 is connected to the spherical gear, and the other end is connected to the prosthetic foot.

[0079] The cross section of the special-shaped gear 2 used for meshing with the spherical gear is the profile of an involute gear, the gear module is 2, the number of gear teeth is 11, which is the same as the cross-sectional gear profile module of the spherical gear, the tooth profile angle is equal, and the transmission ratio is 2:1.

[0080] In this embodiment, the prosthetic foot includes a tray 25, a keel 26, an elastic upper foot blade 27 and a lower blade 28, wherein the magnetic damping connection device is arranged on one surface of the tray 25; the output rod 38 is connected to the tray 25; the keel 26 is connected to the other surface of the tray 25; the elastic upper foot blade 27 is connected to the keel 26; and the lower blade 28 is connected to the keel 26.

[0081] The prosthetic foot further comprises a plantar pressure sensor 39, which is arranged at the contact portion between the elastic foot blade and the ground.

[0082] In this embodiment, a receiving groove is provided on the keel 26;

[0083] The prosthetic foot further includes an inertial measurement unit 36, which is disposed in the receiving groove; and a gyroscope 37, which is disposed at the rear end surface of the keel.

[0084] More specifically, the prosthetic foot 24's tray 25 is screwed to the top of the keel 26. An output rod 38 is fixed to the ball gear 1 at one end and to the tray 25 at the other. The upper and lower blades 27 and 28 of the elastic foot are bolted to the keel 26, providing support for the prosthesis. An inertial measurement unit (IMU) is placed in a groove at the front end of the keel 26 and is responsible for measuring the angular acceleration of the prosthetic foot 24 in the sagittal and coronal planes in real time. A gyroscope 37 is screwed to the rear end of the keel and measures the angular acceleration of the prosthetic foot 24 in the horizontal plane, enabling the recognition of human motion intentions and the real-time control of the trajectory of the output rod 38.

[0085] See also Figure 5 as well as Figure 12 In this embodiment, a through hole is formed below the prosthetic sleeve 14 to facilitate the mating of the ball gear 1 with the special-shaped gear 2. The bottom flat surface of the sleeve 14 is threadedly connected to six connecting posts 15. The internal threads of the connecting posts are threadedly connected to the ball seat 16, which is hingedly connected to the ball rod 17.

[0086] In this embodiment, the magnetic damping connection device includes a magnetic conductive layer 18, a steel cylinder 19, a magnetic base 20, a spiral coil 29, a linear bearing 21, a conductor layer 22, a ball head rod 17, a ball head cover 23, a ball seat 16, and a connecting column 15; wherein,

[0087] The magnetic conductive layer 18 is threadedly connected to the inner wall of the steel cylinder 19, the magnetic base 20 is threadedly connected to the inner wall of the steel cylinder 19, the spiral coil 29 is stuck in the groove of the magnetic base 20, and the two ends of the magnetic base 20 are gaskets 10 and linear bearings 21. The conductor layer 22 is threadedly connected to the ball head rod 17, and the ball head rod 17 drives the conductor layer 22 to move in the steel cylinder 19; the right end of the steel cylinder 19 is screwed to the ball head cover 23, the ball head of the ball head cover 23 is hinged to the ball seat 16, and the ball seat 16 is threadedly connected to the tray 25 through the connecting column 15.

[0088] In this embodiment, the two special-shaped gears 2 are distributed inside the prosthetic sleeve 14 at an angle of 60° to each other, and the meshing planes of the two special-shaped gears 2 and the ball gear 1 are also at an angle of 60°.

[0089] The present application is further described in detail below by way of examples. It should be understood that the examples do not constitute any limitation to the present application.

[0090] See also Figure 2 In this embodiment, ball gear 1 is machined on a spherical surface. The cross-section of ball gear 1 resembles the profile of a conventional involute gear, with a module of 2 and 22 teeth. Rotational cutting is performed around the x- and y-axes, preserving the gear profile in any plane within the rotational circle, resulting in a spherical gear structure.

[0091] See also Figure 2 In this embodiment, profiled gear 2 is fabricated using a process similar to hobbing. The profiled gear's cross-section resembles the profile of a standard involute gear, with a module of 2 and 11 teeth. These are identical to the module of the cross-sectional profile of ball gear 1, and the tooth profile angles are equal, satisfying meshing conditions and resulting in a 2:1 transmission ratio. As the spur gear profiles of ball gear 1 and profiled gear 2 mesh, ball gear 1 acts as a tool to cut profiled gear 2, generating the profiled gear's tooth surfaces.

[0092] See also Figure 3In this embodiment, the motor 3 is connected to the threaded hole of the prosthetic sleeve 14 through the motor support seat 33. The shaft of the motor 3 is directly connected to the small helical gear 4. The normal module of the small helical gear 4 and the large helical gear 5 is 1.5, the normal pressure angle is 20°, the spiral angles are equal in size and opposite in direction, and the meshing conditions are met. The large diameter section of the support shaft 6 is slotted and the two side planes are milled. It is fixedly connected to the connecting shaft 8. The special-shaped gear 2 can rotate around the connecting shaft 8. The bearing 9 is installed inside the special-shaped gear 2 and is positioned by the top shoulder 30 and the gasket 10. The bearing 9 can reduce the friction between the special-shaped gear 2 and the connecting shaft when the meshing rotation is carried out. The slot in the middle diameter section of the support shaft 6 leaves enough room for the small gear 11 to move. There is a positioning hole at the bottom end of the slot, which is threadedly connected to the tail end of the small support rod 12. The small support rod 12 passes through the center hole of the small gear 11 to ensure the position accuracy of the small gear 11. The front section of the inner worm gear 7 is developed into a spiral internal tooth surface, forming a meshing motion relationship with the small gear 11. The rear section of the inner worm gear 7 is provided with a through hole, which is convenient for being put on the middle diameter section of the support shaft 6. When the small gear 11 meshes and rotates with the inner worm gear 7, the inner worm gear 7 can rotate around the fixed axis of the support shaft 6. The small diameter section of the support shaft 6 is used to support the large bevel gear 5. There is a block 31 between the two large bevel gears 5 to ensure the movement space of the two small bevel gears 4. The large bevel gear 5 that rotates around the fixed axis of the support shaft has a bearing inside. The stepped gasket 32 ​​can reduce the friction between the large bevel gear 5 and the block 31 and the support shaft 6, and can also serve as a top shoulder of the bearing. Another large bevel gear 5 is fixedly connected to the support shaft 6 and rotates together. The support shaft 6 is connected to the through-hole bolt on the prosthetic sleeve 14 through the support seat 13.

[0093] See also Figure 1 、 Figure 4 and Figure 14 In this embodiment, a through hole is provided at the bottom of the prosthetic sleeve 14 to facilitate the mating of the ball gear 1 and the special-shaped gear 2. The bottom plane of the sleeve 14 is threadedly connected to the six connecting columns 15. The internal thread of the connecting column is threadedly connected to the ball seat 16, and the ball seat 16 is hinged to the ball head rod 17. The magnetic conductive layer 18 is threadedly connected to the inner wall of the steel cylinder 19, and the magnetic base 20 is threadedly connected to the inner wall of the steel cylinder 19. The spiral coil 29 is stuck in the groove of the magnetic base 20. The two ends of the magnetic base 20 are gaskets 10 and linear bearings 21 to reduce friction. The conductive layer 22 is threadedly connected to the ball head rod 17, and the ball head rod 17 drives the conductive layer 22 to move in the steel cylinder 19, thereby generating a damping force. The right end of the steel cylinder 19 is screwed to the ball head cover 23. The ball head of the ball head cover 23 is hinged to the ball seat 16. The ball seat 16 is threadedly connected to the tray 25 above the prosthetic foot 24 through the connecting column 15.

[0094] See also Figure 5In this embodiment, the prosthetic foot 24's tray 25 is screwed to the top of the keel 26. An output rod 38 is fixedly connected to the ball gear 1 at one end and to the tray 25 at the other. The upper and lower blades 27 and 28 of the elastic foot are bolted to the keel 26, providing support for the prosthesis. An inertial measurement unit 36, placed in a groove at the front end of the keel 26, measures the angular acceleration of the prosthetic foot 24 in the sagittal and coronal planes in real time. A gyroscope 37, screwed to the rear end of the keel, measures the angular acceleration of the prosthetic foot 24 in the horizontal plane, enabling monitoring of the prosthetic foot's motion state and identifying human motion intentions, thereby controlling the trajectory of the output rod 38 in real time.

[0095] See also Figure 6 In actual operation, the interaction between the ball gear 1 and the special-shaped gear 2 produces three kinds of motion: transmission, rolling and sliding motion, and the transmission ratio of the special-shaped gear 2 to the ball gear 1 is 2 to 1. For a single driving special-shaped gear, when the special-shaped gear 2 rotates around the vertical center axis by -2θ N1 When the angle is θ, the ball gear rotates N1 Angle, the teeth of the special-shaped gear 2 mesh with the teeth of the ball gear 1, and the driving force is transmitted from the special-shaped gear 2 to the ball gear 1. When the special-shaped gear 2 rotates around the horizontal axis θ G1 Angle, the ball gear rolls accordingly θ G1 Angle, through the rolling rotation of the special-shaped gear 2, the driving force is transmitted, thereby driving the rolling rotation of the ball gear 1. When the special-shaped gear 2 rotates around the structural axis of the ball gear 1 by θ H1 When the angle is θ, the rotation of ball gear 1 and the tooth surface of profile gear 2 form a passive sliding, and no driving force is transmitted. When the position of profile gear 2 is fixed, the interaction of these three motions will interfere and is not completely independent. A single profile gear 2 can only actively drive two of the three rotational degrees of freedom of ball gear 1, namely the fixed axis rotation θ around the vertical center axis. N1 Angle and horizontal axis fixed axis rotation θ G1 The passive sliding motion is driven by another special-shaped gear 2 or by both special-shaped gears 2. Inside the prosthetic sleeve 14, the drive motor 3 drives the meshing motion of the front small helical gear 4 and the large helical gear 5. The large helical gear 5 rotates relative to the support shaft 6. The large helical gear 5 transmits the driving force to the inner worm gear 7, driving the meshing motion between the small gear 11 and the special-shaped gear 2, and the meshing rotation of the ball gear 1. The drive motor drives the meshing motion of the rear small helical gear 4 and the large helical gear 5. The large helical gear 5 rotates together with the support shaft 6. The support shaft 6 converts the driving force into rolling motion of the special-shaped gear 2 and the ball gear 1 through the support rod 8.

[0096] See also Figure 7 and Figure 8Since a single special-shaped gear 2 and ball gear 1 generate three types of motion, they can be equivalent to three joints: a rolling joint, a meshing joint, and a sliding joint. The rolling and meshing joints are active, while the sliding joints are passive. The rolling joint G1 of the first special-shaped gear 2 is connected to the meshing joint N1 via a spherical link a1, while the meshing joint N1 is connected to the sliding joint H1 via a spherical link a2. Link a0 serves as the fixed support for the drive gear. The rolling joint G2 of the second special-shaped gear 2 is connected to the meshing joint N2 via a spherical link b1, while the meshing joint N2 is connected to the sliding joint H2 via a spherical link b2. Link b0 serves as the fixed support for the drive gear. When ball gear 1 is driven by a single special-shaped gear, the mechanism can be equivalent to a two-link tandem arm with a passive sliding joint as the end effector. Because the links are spherical, the end effector has two sliding degrees of freedom on the sphere, centered at the center of ball gear 1. Therefore, when two special-shaped gears 2 drive ball gear 1, it can be equivalent to being driven by two tandem arms in parallel. Since each arm is connected to the ball gear through a passive joint and all joints are orthogonal, the output link obtains three rotational degrees of freedom. According to the equivalent link model, the degrees of freedom can be obtained from the Gruebler equation:

[0097]

[0098] Where N is the number of links, J is the number of joints, and f i is the degree of freedom of the i-th joint, and the degree of freedom of the equivalent linkage mechanism is 3.

[0099] See also Figure 8 and Figure 9 , the two special-shaped gears 2 and the corresponding drive devices are distributed inside the prosthetic sleeve 14 at an angle of 60°, and the meshing planes of the two special-shaped gears 2 and the ball gear 1 are also 60°. The three degrees of freedom of the ball gear 1 are realized by the coupled motion of the four active joints G1, N1, G2, and N2 of the two special-shaped gears 2, so they can be regarded as three independent active joints G1, N1, and G2 and a subordinate active joint N2. The equivalent joints of the special-shaped gears are connected to the ball gears through equivalent connecting rods, and the rotation angles of the ball gears in three directions can be obtained by the rotation coordinate transformation between the connecting rods. Let the world coordinate system fixed on the bracket (prosthetic sleeve 14) be O, and the coordinate system of the connecting rod a0 coincide with the world coordinate system. The local coordinate system fixed on the ball gear is O A , the coordinate transformation of ball gear and special-shaped gear is expressed as O q C and O q Bi (i=1, 2):

[0100] O q C =R(θ S ,θC ,θ P ), Where θ S is the sagittal rotation angle of ball gear 1, θ C is the crown rotation angle of ball gear 1, θ P is the horizontal rotation angle of ball gear 1, θ Gi is the rolling rotation angle of the i-th special-shaped gear 2, θ Ni is the meshing rotation angle of the i-th special-shaped gear 2, θ Hi is the passive sliding angle of the i-th special-shaped gear 2.

[0101] The relationship between the ball gear and the rotation angle of the two drive modules is as follows:

[0102] θ S1 =θ G1 ,θ S2 =θ G2 ,θ C1 = -2θ N1 ,θ C2 = -2θ N2

[0103] Through the kinematic model, the rotation matrix transformation is performed:

[0104] a0 R a1 =R x (θ G1 ), a1 R a2 =R y (θ N1 ), a2 R C =R x (θ H1 )

[0105] b0 R b1 =R x (θ G2 ), b1 R b2 =R y (θ N2 ), b2 R C =R x (θ H2 )R z (-π / 2), a0 R b0 =R z (β)

[0106]

[0107] Where β is the angle between the meshing planes of the two special-shaped gears 2 and the ball gear 1.

[0108] Due to closed circularity:

[0109] a0 R a1 a1 R a2 a2 R C = a0 R b0 b0 R b1 b1 R b2 b2 R C

[0110] Right now:

[0111]

[0112] The calculation can obtain the slave active joint angle N2, the passive sliding angle H1 and the rotation angles on the three surfaces of the ball gear.

[0113]

[0114]

[0115] θ S =arcsin(sinθ N1 (-cosθ G1 cosθ N1 sinθ G2 +cosθ N1 cosθ G2 sinθ G1 cosβ+sinθ N1 cosθ G2 sinβ))

[0116]

[0117] See also Figure 4 and Figure 14 According to the principle of electromagnetic induction, when the magnetic flux lines generated by the energized solenoid coil 29 are cut by the moving conductor, the moving conductor layer 22 generates an induced electromotive force, which forms eddy currents in the conductor layer 22. These eddy currents stimulate a damping force that hinders the relative motion between the conductor and the magnetic field. When the prosthetic foot 24 moves, the six magnetic dampers 35 extend and retract, generating a supporting force.

[0118] See also Figure 10 and Figure 11The rotation angles of the ball gear 1 in three directions can be known to obtain the end position of the prosthetic foot 24, and thus the analytical expression of the length change of the magnetic damper 35 can be obtained. The hinge point R of the ball joint connecting the bottom plane of the prosthetic sleeve 14 and the prosthetic foot tray 25 is i 、r i (i=1,2,...,6) are connected to form symmetrical hexagons. The bottom plane of the prosthetic sleeve 14 is regarded as the fixed platform, and the top plane of the prosthetic foot tray 25 is regarded as the moving platform. A fixed coordinate system O fixed to the fixed platform is established at the geometric center E of the fixed platform. E , establish a moving coordinate system O fixed to the moving platform at the geometric center D of the moving platform D The radius of the fixed platform is the hinge point R i The distance R to the center point E E , the radius of the moving platform is the hinge point r i The distance R to the center point D D When the platform is in the initial static state, the geometric center D of the moving platform is directly above the geometric center E of the fixed platform.

[0119] See also Figure 12 , hinge point r i In the moving coordinate system O D The position vector in is:

[0120]

[0121] Where φ represents the angle between two adjacent hinge points of the moving platform.

[0122] See also Figure 13 , the position vector of the hinge point Ri in the fixed coordinate system OE can be expressed as:

[0123]

[0124] Where γ represents the angle between two adjacent hinge points of the moving platform.

[0125] Since the geometric center E of the fixed platform coincides with the geometric center C of the ball gear, the coordinate system of the fixed platform is the same as the world coordinate system fixed to the bracket (prosthetic sleeve 14), and the prosthetic foot tray 25 and the ball gear 1 are fixedly connected to the geometric center of the moving platform via the output rod 38, the rotation transformation matrix of the moving platform relative to the fixed platform is equal to the rotation transformation matrix of the ball gear 1 relative to the world coordinate system:

[0126]

[0127] The vector l of the i-th magnetic damper 35 i It can be expressed as:

[0128] l i = E RD D r i +t- E R i (i=1,2,...,6)

[0129] in, E R D Represents the rotation matrix of the moving platform relative to the fixed coordinate system, where l i represents the vector of the magnetic damper 35, i.e., the vector of the connection point between the magnetic damper 35 and the fixed and movable platforms. t represents the translation vector of the geometric center point of the fixed and movable platforms, i.e., the translation vector of the output rod 38.

[0130] The length of the i-th magnetic damper 35 is l i for:

[0131]

[0132] The expansion and contraction variation of the magnetic damper 35 can be expressed as:

[0133] Δl i =l i -l0

[0134] Where l0 is the original magnetic damper length.

[0135] See also Figure 1 and Figure 14 In daily walking tasks, the algorithm is designed to plan the trajectory using the data from the electromyographic signal sensor, the inertial measurement unit 36, the gyroscope 37, and the plantar pressure sensor 39, and to generate a trajectory function for the ball gear 1 moving along the path. O q C (t), the rotation angle θ of the two special-shaped gears 2 can be obtained by matrix inverse transformation N1 ,θ N2 ,θ G1 ,θ G2 The rotation angle of motor 3 that drives the meshing motion of the special-shaped gear 2 on the left and right sides is generated by the inverse kinematics calculation of motor 3-special-shaped gear 2. and the rotation angle of the motor 3 driving the rolling motion of the special-shaped gear 2

[0136] Where i n 、i g is the transmission ratio from motor 3 to special-shaped gear 2.

[0137] While the four motors 3 drive the ball gear 1 synchronously, the magnetic damper 35 performs passive telescopic motion accordingly. O q C (t) The expansion and contraction variation of the magnetic damper 35 obtained by inverse solution Δli As well as the real-time measurement of the position, velocity, acceleration and other motion parameters of the moving platform, the current size is dynamically adjusted to change the magnetic field strength of the magnetic damper, thereby adjusting the damping force in real time to provide support, so that the prosthetic foot 24 can move stably according to the planned trajectory.

[0138] This application has the following advantages:

[0139] 1. The transmission route of motor-helical gear set-internal worm gear-pinion gear-special-shaped gear-ball gear-output end is adopted to make the drive device compact and save space.

[0140] 2. The application of the ball gear and two special-shaped gears realizes three active degrees of freedom of rotation of the prosthetic foot and simplifies the structure of the drive device.

[0141] 3. The magnetic damper can provide different damping forces by changing the current, providing the device with a support force with variable amplitude and direction, thereby achieving stable movement of the prosthetic foot.

[0142] 4. Considering human-computer interaction, the prosthetic sleeve fully considers human comfort.

[0143] 5. The control of three active degrees of freedom combined with sensing technology can achieve real-time adjustment of the prosthetic foot posture, improve the adaptability of the ankle joint prosthesis to different terrains, and enhance system safety.

[0144] 6. Through the coordinated control of three degrees of freedom, the movement of the human natural ankle joint is more accurately simulated, the gait adaptability of the prosthesis is improved, the walking coordination ability of amputees is improved, and the comfort of the human body is improved.

[0145] 7. The magnetic damper platform provides passive damping force to help control the movement of the prosthesis, reduce vibration and impact of the prosthetic foot, and reduce user discomfort.

[0146] 8. The active control of the ball gear combined with the passive damping force of the magnetic damper can meet the damping adjustment requirements of different users to achieve the best gait and comfort.

[0147] Although the present application is disclosed as above with reference to preferred embodiments, it is not intended to limit the present application. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims of the present application.

[0148] Finally, it should be pointed out that the above embodiments are intended only to illustrate the technical solutions of this application and are not intended to limit them. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they may modify the technical solutions described in the above embodiments or replace some of the technical features therein with equivalents; and such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A three-degree-of-freedom ankle prosthesis with a gear mechanism, characterized in that: The three-degree-of-freedom ankle prosthesis with a gear mechanism comprises: prosthetic sleeves; a drive assembly disposed within the prosthetic sleeve and connected to the prosthetic sleeve; a gear motion assembly, the gear motion assembly being disposed within the prosthetic sleeve and meshing with the drive assembly; a magnetic damping connection device, one end of which is connected to the prosthetic sleeve; A prosthetic foot connected to the other end of the magnetic damping connection device; wherein, The driving device assembly is used to drive the gear motion assembly to move, so that the three-degree-of-freedom ankle joint prosthesis with the gear mechanism has three active degrees of freedom of movement; The magnetic damping connection device provides different damping forces by changing the magnitude of the current, thereby providing variable support force to the three-degree-of-freedom ankle joint prosthesis with a gear mechanism; the number of the drive device components is two, and each drive device component includes: a driving device body connected to the prosthetic sleeve; A special-shaped gear (2), the special-shaped gear is connected to the driving device body, and the special-shaped gear is meshed with the gear motion assembly; the driving device body includes a motor assembly (3), a small helical gear (4), a large helical gear (5), an inner worm gear (7), a small gear (11), a connecting shaft (8), a bearing (9), a small support rod (12), a support shaft (6), and a support seat (13); wherein, The motor assembly (3) is connected to the prosthetic sleeve (14); The output shaft of the motor assembly (3) is connected to the small helical gear (4); The small helical gear (4) meshes with the large helical gear (5); The supporting shaft (6) is fixedly connected to the connecting shaft (8); The special-shaped gear (2) is arranged on the connecting shaft (8) and is capable of rotating around the connecting shaft (8); The bearing (9) is installed inside the special-shaped gear (2); The support shaft (6) is threadedly connected to the tail end of the small support rod (12); The front section of the inner worm gear (7) is meshed with the pinion gear (11); wherein, The small diameter section of the support shaft (6) is used to support the large helical gear (5); The support shaft (6) is connected to the prosthetic sleeve (14) through the support seat (13); the gear motion assembly includes a spherical gear (1) and an output rod (38); the cross section of the spherical gear is the profile of an involute gear, the gear module is 2, and the number of teeth is 22; one end of the output rod (38) is connected to the spherical gear, and the other end is connected to the prosthetic foot; The cross section of the special-shaped gear (2) for meshing with the spherical gear is the profile of an involute gear, the gear module is 2, the number of gear teeth is 11, the gear profile module is the same as the cross section of the spherical gear, the tooth angle is equal, and the transmission ratio is 2:1; The prosthetic foot comprises: The tray (25) is provided with the magnetic damping connection device on one surface of the tray (25); and the output rod (38) is threadedly connected to the tray (25).

2. The three-degree-of-freedom ankle prosthesis with a gear mechanism according to claim 1, wherein: The prosthetic foot further comprises: A keel (26), the keel (26) being connected to the other surface of the tray (25); An elastic foot blade (27), wherein the elastic foot blade (27) is connected to the keel (26); An elastic foot lower blade (28), wherein the elastic foot lower blade (28) is connected to the keel (26); A plantar pressure sensor (39) is provided on a portion where the lower blade (28) of the elastic foot contacts the ground.

3. The three-degree-of-freedom ankle prosthesis with a gear mechanism according to claim 2, wherein: The keel (26) is provided with a receiving groove; The prosthetic foot further comprises: an inertial measurement unit (36), the inertial measurement unit (36) being disposed in the accommodating groove; A gyroscope (37) is provided at the rear end surface of the keel.

4. The three-degree-of-freedom ankle prosthesis with a gear mechanism according to claim 3, wherein: A through hole is formed below the prosthetic sleeve (14); The bottom plane of the prosthetic sleeve (14) is threadedly connected to six connecting columns (15); The internal thread of the connecting column is threadedly connected to the ball seat (16), and the ball seat (16) is hinged to the ball head rod (17).

5. The three-degree-of-freedom ankle prosthesis with a gear mechanism according to claim 4, wherein: The magnetic damping connection device comprises a magnetic conductive layer (18), a steel cylinder (19), a magnetic base (20), a spiral coil (29), a linear bearing (21), a conductor layer (22), a ball head rod (17), a ball head cover (23), a ball seat (16), and a connecting column (15); wherein, The magnetic conductive layer (18) is threadedly connected to the inner wall of the steel cylinder (19), the magnetic base (20) is threadedly connected to the inner wall of the steel cylinder (19), the spiral coil (29) is stuck in the groove of the magnetic base (20), the two ends of the magnetic base (20) are gaskets (10) and linear bearings (21), the conductor layer (22) is threadedly connected to the ball head rod (17), and the ball head rod (17) drives the conductor layer (22) to move in the steel cylinder (19); the right end of the steel cylinder (19) is screwed to the ball head cover (23), the ball head of the ball head cover (23) is hinged to the ball seat (16), and the ball seat (16) is threadedly connected to the tray (25) through the connecting column (15).

6. The three-degree-of-freedom ankle prosthesis with a gear mechanism according to claim 5, wherein: The two special-shaped gears (2) are distributed inside the prosthetic sleeve (14) at an angle of 60° to each other, and the meshing planes of the two special-shaped gears (2) and the spherical gear (1) are also at an angle of 60°.

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