CN113456321B

CN113456321B - Bionic active knee joint

Info

Publication number: CN113456321B
Application number: CN202110736421.0A
Authority: CN
Inventors: 任雷; 陈魏; 梁威; 宋厚楠; 钱志辉; 修豪华; 王坤阳
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2021-06-30
Filing date: 2021-06-30
Publication date: 2022-06-21
Anticipated expiration: 2041-06-30
Also published as: CN113456321A

Abstract

The invention discloses a bionic active knee joint, which comprises: two support frames; a drive motor; the ball screw is in transmission connection with a power output shaft of the driving motor; a ball screw nut; the actuator frame is a frame structure formed by enclosing a top plate, a bottom plate and two side plates; the top plate and the bottom plate are simultaneously sleeved on the ball screw in an empty way; the knee joint bending spring is sleeved on the ball screw, one end of the knee joint bending spring is abutted against the top plate, and the other end of the knee joint bending spring is abutted against the ball screw nut; the knee joint extension spring is sleeved on the ball screw, one end of the knee joint extension spring is abutted against the bottom plate, and the other end of the knee joint extension spring is abutted against the ball screw nut; the first synchronous belt wheel is simultaneously connected to the upper ends of the two support frames; the second synchronous belt wheel is simultaneously connected to the lower ends of the two support frames; a synchronous belt which is respectively meshed with the first synchronous belt wheel and the second synchronous belt wheel and is fixedly connected with the actuator frame; a socket interface coupled to the first synchronous pulley.

Description

Bionic active knee joint

Technical Field

The invention belongs to the technical field of active artificial limb knee joints, and particularly relates to a bionic active knee joint.

Background

The above knee artificial limb is used as a unique means which can restore the walking function of a thigh amputation patient and return to the society, and the performance of the above knee artificial limb is very important for the above knee amputation patient to restore the normal gait and improve the walking ability. Above knee prostheses can be largely divided into two types according to the driving style: one is a passive prosthetic knee joint, and the other is an active prosthetic knee joint. Passive prostheses can meet the basic locomotor needs of lower amputees (walking at a relatively constant speed on level ground), but with the need for improved living quality of amputees, their range of motion is expanded, and need to be able to accommodate the walking needs of pace, uphill and downhill, and uphill and downhill steps, which may result in asymmetric gait, secondary injury, and higher metabolic costs for amputees. The active artificial limb realizes the flexion of the knee joint by adopting an external power mode, not only can meet the requirements of walking on flat ground at different pace speeds, but also can meet the requirements of going upstairs, climbing and other scenes needing large torque output, but the current power artificial limb generally has the problems of large energy consumption and incapability of being used for a long time.

Disclosure of Invention

The invention provides a bionic active knee joint, and aims to reduce the energy consumption of the bionic knee joint and overcome the defect of high energy consumption of the conventional active artificial knee joint.

The invention also aims to effectively imitate the gait of the lower limb of the human body when the bionic knee joint moves, thereby adapting to more living scenes and improving the comfort level of a user.

The technical scheme provided by the invention is as follows:

a biomimetic active knee joint comprising:

two support frames symmetrically arranged at intervals;

the driving motor is fixedly arranged on the two support frames;

the ball screw is arranged between the two support frames and is in transmission connection with a power output shaft of the driving motor;

the ball screw nut is connected to the ball screw in a matching manner;

the actuator frame is a frame structure formed by enclosing a top plate, a bottom plate and two side plates; the top plate and the bottom plate are simultaneously sleeved on the ball screw in an empty way;

wherein the ball screw nut is located between the top plate and the bottom plate; the ball screw nut and the actuator frame are movable in an axial direction of the ball screw, respectively;

the knee joint bending spring is sleeved on the ball screw, one end of the knee joint bending spring is abutted against the top plate, and the other end of the knee joint bending spring is abutted against the ball screw nut;

the knee joint extension spring is sleeved on the ball screw, one end of the knee joint extension spring is abutted against the bottom plate, and the other end of the knee joint extension spring is abutted against the ball screw nut;

the first synchronous belt wheel is rotatably connected to the upper ends of the two support frames;

wherein the axis of the first synchronous pulley is perpendicular to the axis of the ball screw;

a second timing pulley provided in parallel with the first timing pulley; the supporting frames are rotatably connected to the lower ends of the two supporting frames;

a timing belt engaged with the first timing pulley and the second timing pulley, respectively, and fixedly connected to the actuator frame;

a socket interface fixedly connected with the first synchronous pulley.

Preferably, the driving motor is located at one side of the actuator frame and spaced apart from the ball screw;

the driving motor is fixedly installed on the driving motor base, and the driving motor base is simultaneously and fixedly connected to the two supporting frames.

Preferably, the bionic active knee joint further comprises:

the synchronous belt guide frame is fixedly connected to the driving motor base; the upper end and the lower end of the synchronous belt guide frame are respectively provided with a rotatable guide wheel;

wherein, driving motor is located ball screw with between the hold-in range leading truck, the hold-in range is walked around two simultaneously the leading wheel to support on two the leading wheel.

Preferably, the bionic active knee joint further comprises:

a synchronous belt connecting plate fixedly connected to the other side of the actuator frame;

the synchronous belt connecting plate comprises a first pressing plate and a second pressing plate which are symmetrically arranged, and the synchronous belt is fixedly connected between the first pressing plate and the second pressing plate.

Preferably, a power output shaft of the driving motor is arranged in parallel with the ball screw and is driven by a speed reducing synchronous belt.

Preferably, a power output shaft of the driving motor is coaxially and fixedly connected with a driving belt pulley, and the ball screw is coaxially and fixedly connected with a driven belt pulley;

the speed reducing synchronous belt is sleeved on the driving belt wheel and the driven belt wheel at the same time and is in meshing transmission with the driving belt wheel and the driven belt wheel respectively.

Preferably, the knee joint extension spring and the knee joint bending spring both adopt die springs;

wherein the stiffness of the knee joint extension spring is 419N/mm, and the stiffness of the knee joint bending spring is 380N/mm.

Preferably, the socket connector comprises:

the top seat is arranged above the first synchronous belt pulley, and a rectangular pyramid connecting piece is arranged at the top of the top seat and is used for connecting a receiving cavity;

the two connecting discs are symmetrically and fixedly arranged on two sides of the top seat;

the two connecting discs are respectively and fixedly connected with two ends of the first synchronous belt wheel.

Preferably, the bionic active knee joint further comprises:

the ankle joint connecting body is fixedly arranged at the lower end of the supporting frame; the lower end of the ankle joint connector is provided with a rectangular pyramid connector used for connecting an ankle joint prosthesis.

Preferably, the bionic active knee joint further comprises:

the driving motor encoder is arranged on the driving motor and used for acquiring the rotation angle of the driving motor;

the joint encoder comprises a PCB board and a rotor magnetic ring;

the PCB is fixedly connected to the support frame, and the rotor magnetic ring is fixedly arranged on a pulley shaft of the second synchronous pulley;

the pressure sensor is provided with a base, and the base of the pressure sensor is simultaneously and fixedly connected to the lower ends of the two support frames; and the pressure sensor is positioned between the ankle joint connector and the support frame.

The invention has the beneficial effects that:

(1) according to the bionic active knee joint provided by the invention, the knee joint is driven by the synchronous belt, a larger buckling angle of the active knee joint can be realized under the condition of meeting the compact structure, and the bionic active knee joint is suitable for more living scenes, and meanwhile, the artificial limb can be used for swinging to drive the driving motor to rotate to generate electricity in the swinging phase, so that a storage battery is charged, and the requirement on the capacity of the storage battery is reduced.

(2) According to the bionic active knee joint provided by the invention, energy is stored through the spring, the energy consumption of the driving motor is reduced, the consumption of the capacity of the storage battery is reduced, the weight of the storage battery is reduced, and the high efficiency and the light weight of the knee joint artificial limb are realized.

(3) According to the bionic active knee joint provided by the invention, the rigidity of the used spring corresponds to the bending rigidity and the stretching rigidity of the knee joint of a human body, and the gait of the lower limb of the human body when walking on the flat ground can be effectively simulated when the driving motor is not driven, so that the energy output of the hip joint is reduced, and the comfort level of a user is improved.

Drawings

Fig. 1 is a schematic view of the overall structure of the bionic active knee joint of the present invention.

FIG. 2 is a side view of a biomimetic active knee joint in accordance with the present invention.

Fig. 3 is a schematic structural diagram of the bionic active knee joint without a synchronous belt.

FIG. 4 is a rear view of the bionic active knee joint without a synchronous belt.

FIG. 5 is a side view of the bionic active knee joint without a synchronous belt.

Fig. 6 is an exploded view of a socket connector according to the present invention.

Fig. 7 is an exploded view of the driving motor and the motor base according to the present invention.

FIG. 8 is an exploded view of the first synchronous pulley assembly of the present invention.

Fig. 9 is an exploded view of a second synchronous pulley assembly according to the present invention.

FIG. 10 is a schematic view of the knee joint angle during walking on level ground.

Detailed Description

The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.

As shown in fig. 1 to 9, the present invention provides a bionic active knee joint, which mainly comprises: the device comprises a top seat 1, a connecting disc 2, a support frame 3, a ball screw 4, a synchronous belt 5, a micro linear guide rail slider 6, a ball screw nut 7, a micro linear guide rail 8, a driving motor seat 9, a bearing seat 10, a joint encoder 11, a pressure sensor base 12, a second synchronous pulley assembly 13, a lower guide wheel 14, a driving motor 15, a guide wheel support 16, an upper guide wheel 17, a driving motor encoder 18, an actuator frame 19, a linear slide rail 20, a support frame 21, a first synchronous pulley assembly 22, a linear slide rail slider 23, a knee joint bending spring 24, a first pressing plate 25, a second pressing plate 26, a knee joint extension spring 27, a driven pulley 28, a driving pulley 29, a deceleration synchronous belt 30, a driving motor shaft bearing end cover 31, a ball screw bearing end cover 32, a support bearing 33, a driving motor shaft bearing 34, an angular contact bearing 35 and a bearing positioning nut 36.

The support frames 3 and the support frames 21 are symmetrically arranged at intervals along the vertical direction. The driving motor 15 is fixedly arranged on the support frame 3 and the support frame 21 through the driving motor base 9. Two ends of the driving motor base 9 are respectively fixedly connected to the side edges of the support frame 3 and the support frame 21, the driving motor 15 is located on the front side of the support frame 3 and the front side of the support frame 21 and is close to the lower portions of the support frame 3 and the support frame 21, and a power output shaft of the driving motor 15 is arranged in the vertical direction.

The ball screw 4 is disposed between the support frame 3 and the support frame 21, and the ball screw 4 is disposed in a vertical direction (i.e., in parallel with the power output shaft of the driving motor 15). The bearing seat 10 is arranged between the support frame 3 and the support frame 21, and two ends of the bearing seat 10 are respectively fixedly connected with the support frame 3 and the support frame 21 through screws. The angular contact bearing 35 is fixedly arranged at the lower end of the ball screw 4 through a bearing positioning nut 36; the ball screw 4 is connected to the bearing block 10 via an angular contact bearing 35. The lower end of the power output shaft of the drive motor 15 is mounted in the bearing housing 10 by a drive motor shaft bearing 34. The lower side of the bearing seat 10 is provided with a driving motor shaft bearing end cap 31 and a ball screw shaft bearing end cap 32 corresponding to the driving motor shaft bearing 34 and the angular contact bearing 35, respectively.

A driving belt pulley 29 is coaxially and fixedly connected to a power output shaft of the driving motor 15, and a driven belt pulley 28 is coaxially and fixedly connected to the ball screw 4; the deceleration synchronous belt 30 is sleeved on the driving pulley 29 and the driven pulley 28 at the same time, and is in mesh transmission with the driving pulley 29 and the driven pulley 28 respectively. The driving motor 15 transmits power to the ball screw 4 through the reduction timing belt 30, thereby driving the ball screw 4 to rotate. The speed reduction and torque increase can be achieved by providing the speed reduction synchronous belt 30. Wherein the driving pulley 29 is fastened on the power output shaft of the driving motor 15 by a jackscrew.

The ball screw nut 7 is connected on the ball screw 4 in a matching way. The actuator frame 19 is arranged between the support frame 3 and the support frame 21, and the actuator frame 19 is a rectangular frame structure enclosed by a top plate 19a, a bottom plate 19b and two

side plates

19c and 19 d; the actuator frame 19 has through holes opened at the centers of the top plate 19a and the bottom plate 19b, respectively, and the top plate 19a and the bottom plate 19b are simultaneously fitted over the ball screw 4 through the through holes, respectively. Wherein the ball screw nut 7 is located between the top plate 19a and the bottom plate 19 b.

The knee joint extension spring 27 is sleeved on the ball screw 4 and is positioned below the ball screw nut 7, one end of the knee joint extension spring 27 is abutted against the bottom plate 19b, and the other end is abutted against the ball screw nut 7; the knee joint bending spring 24 is sleeved on the ball screw 4 and is positioned above the ball screw nut 7, one end of the knee joint bending spring 24 is abutted against the top plate 14b, and the other end of the knee joint bending spring is abutted against the ball screw nut 7.

Linear slide rails 20 are respectively arranged on the inner sides of the support frame 3 and the support frame 21, and the two linear slide rails 20 are respectively arranged along the axis of the ball screw 4; the outer sides of the two

side plates

19c, 19d of the actuator frame 19 are respectively provided with linear slide rail sliders 23, and are movably connected to the two linear slide rails 20 through the linear slide rail sliders 23. By providing the linear guide 20, the actuator frame 19 can move only linearly along the linear guide 20 (the axial direction of the ball screw 4).

The two

side plates

19c and 19d of the actuator frame 19 are fixedly connected with miniature linear guide rails 8 at the front sides thereof, and the two miniature linear guide rails 8 are arranged along the axial direction of the ball screw 4. The ball screw nut 7 is fastened and connected with the two micro linear guide rail sliders 6 through screws and movably connected to the micro linear guide rail 8 through the two micro linear guide rail sliders 6, so that the ball screw nut 7 can only make linear motion relative to the elastic actuator frame 19 along the micro linear guide rail 8 (the axial direction of the ball screw 4).

The first synchronous pulley assembly 22 is disposed between the support frame 3 and the support frame 21, and is rotatably coupled to upper ends of the support frame 3 and the support frame 21. The first synchronous pulley assembly 22 is mainly composed of a pulley disc 2201, a first synchronous pulley 2202, a pulley fixing pin 2203, a pulley shaft 2204 and a pulley disc 2205. The pulley shaft 2204 is connected with a pulley disc 2201 and a pulley disc 2205 through splines, and the upper side pulley 2202 is connected with the right end pulley disc on the upper side of 2201 and the left end pulley disc on the upper side of 2205 through an upper side pulley fixing pin 2203. Wherein, the axis of the first synchronous pulley 2202 is perpendicular to the axis direction of the ball screw 4.

The second synchronous pulley assembly 13 is disposed between the support frame 3 and the support frame 21, and is rotatably connected to lower ends of the support frame 3 and the support frame 21. The second timing pulley assembly 13 is mainly composed of a pulley shaft 1301, a pulley support bearing 1302, a pulley disc 1303, a pulley fastening nut 1304, a second timing pulley 1305, a pulley fixing pin 1306, and a pulley disc 1307. Wherein the second timing pulley 1305 is connected to the pulley disk 1303 and the pulley disk 1307 by a pulley fixing pin 1306; a second timing pulley 1305 is provided in parallel with the first timing pulley 2202.

The actuator frame 19 is connected to the first and second

pressing plates

25 and 26 by screws, and the timing belt 5 is installed between the first and second

pressing plates

25 and 26 such that the actuator frame 19 can drag the timing belt 5 to move. The synchronous belt 5 is simultaneously installed on the first synchronous pulley assembly 22 and the second synchronous pulley assembly 13 and is respectively meshed with the first synchronous pulley 2202 and the second synchronous pulley 1305; the movement of the timing belt 5 may rotate the first timing pulley 2202 and the second timing pulley 1305.

The socket connector comprises: a top seat 1 and two connecting discs 2; the top seat 1 is arranged above the first synchronous belt pulley assembly 22, and the top of the top seat 1 is provided with a rectangular pyramid connecting piece 1a for connecting with a receiving cavity. The two connecting discs 2 are symmetrically arranged on two sides of the top seat 1; belt pulley dish 2201 and belt pulley dish 2205 pass through the screw with respectively with two connection pads 2 fastening connection, two connection pads 2 respectively through screw and footstock 1 fastening connection, two connection pads 2 are connected with support frame 3 and support frame 21 through support bearing 33 respectively for support frame 3 and support frame 21 can rotate around connection pad 2.

The actuator frame 19, the knee extension spring 27 and the knee flexion spring 24 constitute a tandem elastic actuator. Through the spring energy storage, can reduce driving motor to the consumption of energy, reduce the demand to battery capacity, alleviate battery weight, realize knee joint artificial limb high efficiency and lightweight.

Preferably, the knee joint extension spring 27 and the knee joint bending spring 24 both adopt mould springs, and the spring stiffness is matched according to the walking data of a healthy human body; wherein the stiffness of the knee joint extension spring is 419N/mm, and the stiffness of the knee joint bending spring is 380N/mm.

The bionic active knee joint further comprises a synchronous belt guide frame. The hold-in range leading truck includes: a guide wheel bracket 16, a lower guide wheel 14 and an upper guide wheel 17; the guide wheel bracket 16 is fixedly connected to the outer side of the driving motor base 9, namely the driving motor 15 is positioned between the ball screw 4 and the guide wheel bracket 16; the lower guide wheel 14 and the upper guide wheel 17 are rotatably mounted at the upper and lower ends of the guide wheel bracket 16, respectively. The lower guide wheel 14 and the upper guide wheel 17 are supported inside the timing belt 5, and guide the timing belt 5.

The bionic active knee joint also comprises an ankle joint connector which is fixedly arranged at the lower ends of the support frame 3 and the support frame 21; the lower end of the ankle joint connector is provided with a rectangular pyramid connector used for connecting an ankle joint prosthesis.

The driving motor encoder 18 is installed on the driving motor 15, and is used for acquiring the rotation angle of the driving motor. The joint encoder 11 comprises a PCB board and a rotor magnetic ring; the PCB is fixedly connected to the support frame 3, and the rotor magnetic ring is fixedly arranged on a pulley shaft 1301 of the second synchronous pulley through a radial limiting screw. The pressure sensor 12 is integrated with a base, and the base of the pressure sensor 12 is simultaneously and fixedly connected with the lower ends of the two

support frames

3 and 21; and the pressure sensor 12 is located between the ankle joint connection and the two bracing

struts

3, 21.

As shown in fig. 10, when walking on flat ground, the knee joint motion can be divided into a stance phase and a swing phase, wherein the stance phase can be subdivided into a touchdown flexion phase, a touchdown extension phase and a pre-swing phase according to touchdown events; the swing phase can be subdivided into a swing flexion phase and a swing extension phase.

A flat ground walking standing phase takes 3701 heel touchdown as an initial position, the knee joint flexion angle is adjusted to be about 4 degrees through the driving motor 15 before the heel touchdown, when the data acquired by the base of the pressure sensor 12 is more than 5% of the body weight of a human body, the artificial limb wearer completes the heel touchdown and enters the touchdown flexion period; in the ground-contact buckling period, the driving motor 15 is controlled by a position ring to keep a fixed position, because the speed reduction and torque increase are realized by the synchronous belt and the ball screw has a larger transmission ratio, the motor can realize the locking of the ball screw nut 7 only by providing smaller torque at the moment, the knee joint extension spring 27 is gradually compressed along with the increase of the knee joint buckling angle, and the gravitational potential energy part of the human body is converted into the elastic potential energy of the knee joint extension spring 27; according to normal walking gait, when the knee joint angle reaches about 20 degrees, the knee joint finishes the ground-contacting buckling period, the knee joint angular velocity is changed from positive to negative, namely 3702 the knee joint angular velocity is less than 0 degree/second, the ground-contacting stretching period is started, and the knee joint gradually stretches under the action of the knee joint stretching spring 27 along with the forward movement of the gravity center of the human body until the knee joint angle approaches 0 degree; when the knee joint is bent and flexed, the knee joint angular velocity is changed from negative to positive, namely 3703 the knee joint angular velocity is greater than 0 degree/second, the knee joint enters a pre-swing period and continues to flex, when the flexion angle reaches about 20 degrees, the driving motor 15 continues to drive the knee joint to flex through speed loop control until an event 3705 toe-off occurs, and at the moment, data acquired by the base of the pressure sensor 12 is close to 0 Newton, and a standing phase is completed.

When the data acquired by the base of the pressure sensor 12 is 0 newton, an event 3705 is completed, a swing phase is entered, the driving motor 15 is controlled by a rotating speed ring, when the knee joint rotation angle reaches about 60 degrees, the rotating speed of the driving motor 15 is 0 degree/second, then the driving motor 15 rotates reversely, the angular speed value is negative, an event 3706 occurs, a swing extension period is entered, the driving motor 15 is controlled by a current ring to accelerate and decelerate first, a damping effect is achieved, the purpose of impedance control is achieved, a part of kinetic energy is used for compressing the knee joint bending spring 24, and finally when the flexion angle approaches 0 degree, the elastic potential energy of the knee joint bending spring 24 is transferred into the knee joint extension spring 27 through the ball screw nut 7, and energy is stored and distributed for knee joint extension in the next state period.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.

Claims

1. A biomimetic active knee joint, comprising:

two support frames symmetrically arranged at intervals;

the driving motor is fixedly arranged on the two support frames;

the ball screw nut is connected to the ball screw in a matching manner;

the second synchronous belt wheel is arranged in parallel with the first synchronous belt wheel, and is rotatably connected to the lower ends of the two support frames;

the synchronous belt connecting plate comprises a first pressing plate and a second pressing plate which are symmetrically arranged, and the synchronous belt is fixedly connected between the first pressing plate and the second pressing plate; the actuator frame is connected with the first pressing plate and the second pressing plate through screws, and the synchronous belt is arranged between the first pressing plate and the second pressing plate, so that the actuator frame can drag the synchronous belt to move;

a socket connector fixedly connected with the first synchronous pulley;

the socket interface includes:

the two connecting discs are respectively and fixedly connected with two ends of the first synchronous belt wheel; the two connecting discs are respectively connected with the two supporting frames through supporting bearings.

2. The biomimetic active knee joint according to claim 1, wherein the drive motor is located at one side of the actuator frame and spaced apart from the ball screw;

3. The biomimetic active knee joint of claim 2, further comprising:

4. The biomimetic active knee joint according to claim 3, wherein the power output shaft of the driving motor is disposed in parallel with the ball screw and is driven by a deceleration synchronous belt.

5. The bionic active knee joint as claimed in claim 4, wherein a driving pulley is coaxially and fixedly connected to a power output shaft of the driving motor, and a driven pulley is coaxially and fixedly connected to the ball screw;

6. The bionic active knee joint as claimed in claim 5, wherein the knee joint extension spring and the knee joint bending spring are both mold springs;

7. The biomimetic active knee joint of claim 6, further comprising:

8. The biomimetic active knee joint according to claim 7, further comprising:

the joint encoder comprises a PCB board and a rotor magnetic ring;