CN113456322B

CN113456322B - Bionic knee joint based on motor drive

Info

Publication number: CN113456322B
Application number: CN202110736422.5A
Authority: CN
Inventors: 任雷; 陈魏; 梁威; 曹宇; 钱志辉; 王坤阳; 修豪华
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2021-06-30
Filing date: 2021-06-30
Publication date: 2022-09-23
Anticipated expiration: 2041-06-30
Also published as: CN113456322A

Abstract

The invention discloses a bionic knee joint based on motor driving, which comprises: a prosthesis frame; the driving motor is fixedly arranged on the artificial limb rack; the ball screw is connected with the power output shaft of the driving motor; the ball screw nut is connected to the ball screw in a matching manner; the spring seat is sleeved on the ball screw in an empty mode and is fixedly connected with the ball screw nut; the top plate and the bottom plate of the actuator frame are simultaneously sleeved on the ball screw in an empty mode; 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 spring seat; 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 receiving cavity connecting body is rotatably connected to the other end of the artificial limb rack; the two connecting rods are symmetrically arranged on two sides of the ball screw; one end of the connecting rod is hinged with the accepting cavity connecting body, and the other end of the connecting rod is hinged with the actuator frame.

Description

Bionic knee joint based on motor drive

Technical Field

The invention belongs to the technical field of active artificial limb knee joints, and particularly relates to a motor-driven bionic 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 step 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, incapability of being used for a long time, high frequency noise caused by high rotating speed of a motor and low comfort.

Disclosure of Invention

The invention provides a motor-driven bionic 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 limb knee joint.

The invention provides a motor-driven bionic knee joint, and the other purpose of the invention is to reduce the noise of the bionic knee joint and overcome the defect of high noise of the current active artificial limb 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 motor-driven biomimetic knee joint, comprising:

a prosthesis frame;

the driving motor is fixedly arranged on the artificial limb rack;

a ball screw connected to a power output shaft of the driving motor;

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

the spring seat is sleeved on the ball screw in an empty mode and is fixedly connected with the ball screw nut;

an actuator frame disposed proximate one end of the prosthesis support; 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 mode;

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

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

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

the receiving cavity connecting body is rotatably connected to the other end of the artificial limb rack;

the two connecting rods are symmetrically arranged on two sides of the ball screw; one end of the connecting rod is hinged with the accepting cavity connecting body, and the other end of the connecting rod is hinged with the actuator frame.

Preferably, the prosthesis frame is provided with a first linear slide rail along the axial direction of the ball screw, and the actuator frame is movably connected to the first linear slide rail.

Preferably, the bionic knee joint based on motor drive further comprises:

a second linear guide fixedly provided on the actuator frame and arranged in an axial direction of the ball screw;

wherein the spring seat is movably connected to the second linear guide rail.

Preferably, the ball screw is connected to the power output shaft through a coupling.

Preferably, the bionic knee joint based on motor drive further comprises:

the bearing seat is fixedly arranged on the prosthesis stand;

a bearing mounted on the bearing housing;

wherein the ball screw is rotatably supported in the bearing.

Preferably, the bearing is an angular contact bearing.

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

Preferably, the knee joint extension spring rate is 419N/mm and the knee joint flexion spring rate is 380N/mm.

Preferably, the bionic knee joint based on motor drive further comprises:

and the ankle joint connecting body is arranged at the other end of the artificial limb rack.

Preferably, the bionic knee joint based on motor drive further comprises:

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

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

the rotor magnetic ring is fixedly arranged at the hinged point of the connecting rod and the receiving cavity connecting body;

a pressure sensor disposed between the ankle joint connector and the prosthesis frame.

The beneficial effects of the invention are:

(1) the bionic knee joint based on motor driving provided by the invention is directly connected with the ball screw through the driving motor, has a compact structure and high transmission efficiency, can meet the torque requirement only through a small transmission ratio due to high torque density of the motor, and can utilize the lower limb artificial limb to swing and drag the motor to rotate to generate power in a swinging phase so as to charge a storage battery and reduce the requirement on the capacity of the storage battery.

(2) According to the bionic knee joint based on motor driving, the energy is stored through the spring, the energy consumption of the driving motor is reduced, the capacity consumption 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 motor-driven bionic knee joint, the buckling springs and the extension springs are compressed die springs, so that the high-density bionic knee joint has the advantages that the size of the knee joint can be effectively reduced, and the wearability of the knee joint is improved.

(4) According to the motor-driven bionic knee joint, the driving motor is directly connected with the ball screw, the transmission ratio is small, the rotating speed of the driving motor is effectively reduced under the condition of the same knee joint swinging angular speed, the noise of an artificial limb driving system is reduced, and the comfort is improved.

(5) According to the motor-driven bionic 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 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 general structural diagram of a motor-driven bionic knee joint according to the present invention.

Fig. 2 is a rear view of a motor-driven bionic knee joint according to the invention.

Fig. 3 is a front view of a bionic knee joint based on motor driving according to the invention.

Fig. 4 is a schematic structural view of a socket connector according to the present invention.

FIG. 5 is a schematic view showing the knee joint angle during walking on flat 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 4, the present invention provides a motor-driven bionic knee joint, which mainly comprises: the device comprises a motor encoder 1, a driving motor 2, a coupler 3, a bearing 4, a ball screw 5, a first linear sliding rail 6, a knee joint bending spring 7, a ball screw nut 8, a spring seat 9, a knee joint extension spring 10, a pressure sensor 11, an ankle joint connecting body 12, an actuator frame 13, a prosthetic framework 14, a connecting rod 15, a bearing seat 16, a bearing end cover 17, a motor seat 18, a receiving cavity connecting body 19, a rectangular pyramid connecting part 20, a second linear guide rail 21, a sliding block 22, a connecting rod lower end hinge pin 23, a connecting rod upper end hinge pin 24, a knee joint 25, a knee joint encoder 26 and a storage battery.

The prosthesis frame 14 is a frame structure and comprises two

side plates

14a and 14b and a bottom plate 14c which are symmetrically arranged at intervals; wherein the bottom plate 14c is disposed in a horizontal direction and the two

side plates

14a and 14b are disposed in a vertical direction. The drive motor 2 is located between the two

side plates

14a and 14b and is fixedly mounted on the prosthesis housing 14 via a motor mount 18. The accumulator (not shown) is mounted on the prosthesis housing 14 for supplying the drive motor 2.

The power output shaft of the driving motor 2 is connected with the fixed end (upper end) of the ball screw 5 through a coupler 3; the ball screw nut 8 is connected to the ball screw 5 in a matching manner. The spring seat 9 is sleeved on the ball screw 5 in an empty way, and the spring seat 9 is positioned below the ball screw nut 8 and is fixedly connected with the ball screw nut 8 through a screw; the ball screw nut 8 and the spring seat 9 are moved in synchronization.

The actuator frame 13 is disposed adjacent the lower end of the prosthesis frame 14; the actuator frame 13 is a rectangular frame structure formed by enclosing a top plate 13a, a bottom plate 13b and two

side plates

13c and 13 d; the actuator frame 13 has through holes opened at the centers of the top plate 13a and the bottom plate 13b, respectively, and the top plate 13a and the bottom plate 13b are simultaneously fitted over the ball screw 5 through the through holes, respectively. Wherein the ball screw nut 8 together with the spring seat 9 is located between the top plate 13a and the bottom plate 13 b; the spring seat 9 and the actuator frame 13 are respectively movable in the axial direction of the ball screw 5.

The knee joint bending spring 7 is sleeved on the ball screw 5, one end of the knee joint bending spring 7 abuts against the top plate 13a, and the other end of the knee joint bending spring 7 abuts against the ball screw nut 8; the knee joint extension spring 10 is sleeved on the ball screw 5, and one end of the knee joint extension spring 10 abuts against the bottom plate 13b, and the other end abuts against the spring seat 9. The actuator frame 13, the knee flexion spring 7 and the knee extension spring 10 constitute a serial elastic drive. Through the energy storage of the spring, the consumption of the driving motor to energy can be reduced, the requirement on 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.

The two sides of the receiving cavity connecting body 19 are respectively rotatably connected with the upper ends of the two

side plates

14a and 14b of the artificial limb rack 14 through a knee joint hinge pin 25, and the upper end of the receiving cavity connecting body 19 is fixedly provided with a rectangular pyramid connecting part 20 for connecting with an artificial limb receiving cavity at the upper part of the knee joint. Wherein the rectangular pyramid connecting part 20 is connected with the receiving cavity connecting body 19 through threads. Two connecting rod connecting parts 19a are arranged on one side of the receiving cavity connecting body 19 facing the motor; the two link connection portions 19a are symmetrically disposed at both sides of the driving motor 2. Two connecting rods 15 are symmetrically arranged on both sides of the ball screw 5. Wherein, a link connecting part 13aa is arranged on the upper side of the top plate 13a of the actuator frame 13; the two link connecting portions 13aa are located on both sides of the ball screw 5, respectively. The upper ends of the two links 15 are hinged to the corresponding link connecting portions 19a by link upper end hinge pins 24, and the lower ends of the two links 15 are hinged to the corresponding link connecting portions 13aa by link lower end hinge pins 23.

The bearing seat 16 is fixedly arranged on the prosthesis stand 14, and the bearing 4 is arranged on the bearing seat 16; a bearing end cover 17 is arranged above the bearing 4. Wherein the bearing 4 is located between the actuator frame 13 and the coupling 3. The ball screw 5 is rotatably supported in the bearing 4. Preferably, the bearing 4 is an angular contact bearing.

In the embodiment, the inner sides of the two

side plates

14a and 14b of the prosthesis frame are respectively provided with a linear slide rail 6, and the two linear slide rails 6 are respectively arranged along the axis of the ball screw 5; the two

side plates

13c, 13d of the actuator frame 13 each have a slide on their outer side and are connected to the first linear guide 6 in a displaceable manner by means of said slides. By providing the linear guide 6, the actuator frame 13 can move only linearly in the axial direction of the ball screw 5.

The rear sides of the two

side plates

13c, 13d of the actuator frame 13 are fixedly connected with second linear guides 21, respectively, and both the second linear guides 21 are disposed along the axial direction of the ball screw 5. Two sides of the spring seat 9 are respectively fixedly connected with a sliding block 22 through screws, the sliding block 22 is arranged on the second linear guide rail 21 in a matching manner, and the spring seat 9 is movably connected to the second linear guide rail 21 through the sliding block 22. By providing the second linear guide 21, the spring bearing 9 and the ball screw nut 8 can move only linearly in the axial direction of the ball screw 5.

Preferably, the knee joint bending spring 7 and the knee joint extension spring 10 both adopt die springs; the spring stiffness is matched according to the walking data of the healthy human body. Wherein the stiffness of the knee joint extension spring 10 is 419N/mm, and the stiffness of the knee joint bending spring 7 is 380N/mm. The spring stiffness is set to be corresponding to the buckling stiffness and the stretching stiffness of the knee joint of the human body, and the gait of the lower limbs of the human body when walking on the flat ground can be effectively simulated when the motor is not driven, so that the electric motor can adapt to more living scenes, and the comfort level of a user is improved.

The ankle joint connecting body 12 is fixedly arranged at the lower end of the prosthesis frame 14, and the lower end of the ankle joint connecting body 12 is provided with a rectangular pyramid connecting part for connecting an ankle joint prosthesis.

The motor encoder 1 is arranged on the driving motor 2 and used for acquiring the rotation angle of the driving motor 2; the PCB of the knee joint encoder 26 is fixedly connected on the accepting cavity connecting body 19 through screws, and the rotor magnetic ring of the knee joint encoder 26 is fixed on the knee joint hinge pin 25 through radial limit screws. The pressure sensor 11 is arranged between the ankle joint connector 12 and the artificial limb rack 14 and is used for collecting the load born by the bionic knee joint.

The knee joint is completely straightened and specified as the 0-degree position of a knee joint encoder 26, a driving motor 2 drives a ball screw 5 to drive a ball screw nut 8 to move upwards, a knee joint bending spring 7 pushes an elastic actuator frame 13 to move upwards, the elastic actuator frame 13 drives a connecting rod 15, and finally a receiving cavity connecting body 19 is pushed to rotate around a knee joint hinge pin 25, so that the bending of the knee joint is realized, and the angle of the knee joint is gradually increased; otherwise, the knee joint is stretched, and the angle of the knee joint is gradually reduced. The angular velocity of rotation of the knee joint can be determined by the first derivative of the knee joint angle with respect to time.

As shown in fig. 5, 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.

In the flat ground walking standing phase, 2701 heel contact is taken as an initial position, before heel contact is carried out, the bending angle of the knee joint is adjusted to be about 4 degrees through the driving motor 2, when data collected by the pressure sensor 11 is more than 5% of the weight of a human body, a prosthesis wearer finishes heel contact and enters the bending period of the knee contact, in the bending period of the knee contact, the driving motor 2 keeps a fixed position through position ring control, as the roller screw rod has a larger transmission ratio, the driving motor 2 only needs to provide smaller torque to realize the locking of the ball screw nut 8, and as the bending angle of the knee joint is increased, the knee joint extension spring 10 is gradually compressed, and the gravitational potential energy part of the human body is converted into the elastic potential energy of the knee joint extension spring 10; according to normal walking gait, when the angle of the knee joint reaches about 20 degrees, the knee joint finishes the ground-contacting buckling period, the angular velocity of the knee joint is changed from positive to negative, namely the angular velocity of the 2702 knee joint is less than 0 degree/second, the knee joint enters the ground-contacting stretching period, and the knee joint gradually stretches under the action of the 10 knee joint stretching spring along with the forward movement of the gravity center of the human body until the angle of the knee joint approaches 0 degree; when the knee joint bends and bends, the knee joint angular velocity is changed from negative to positive, namely the angular velocity of the 2703 knee joint is greater than 0 degree/second, the knee joint enters a pre-swing period and continues to bend, when the bending angle reaches about 20 degrees, the driving motor 2 continues to drive the knee joint to bend through speed loop control until an event 2705 occurs in toe-off, and at the moment, the data collected by the pressure sensor 11 is close to 0 Newton, so that the standing phase is completed.

When the data collected by the pressure sensor 11 is 0 newton, the event 2705 is completed, the swing phase is entered, the driving motor 2 is controlled by a rotating speed ring, when the knee joint angle reaches about 60 degrees, the rotating speed of the driving motor 2 is 0 degree/second, then the driving motor 2 rotates reversely, the angular speed value is negative, the event 2706 occurs, the swing extension phase is entered, the motor is controlled by a current ring to realize the purposes of first accelerating and then decelerating, the damping effect is realized, the impedance control is realized, part of the kinetic energy is used for compressing the knee joint bending spring 7, and finally when the flexion angle is close to 0 degree, the elastic potential energy of the knee joint bending spring 7 is transferred into the knee joint extension spring 10 through the ball screw nut 8, and the energy is stored and distributed for the 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 bionic knee joint based on motor drive is characterized by comprising:

a prosthesis frame;

the driving motor is fixedly arranged on the artificial limb rack;

the ball screw is connected with a power output shaft of the driving motor;

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

an actuator frame disposed proximate one end of the prosthesis frame; 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 mode;

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 two connecting rods are symmetrically arranged on two sides of the ball screw; one end of the connecting rod is hinged with the accepting cavity connecting body, and the other end of the connecting rod is hinged with the actuator frame;

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

2. The motor-driven biomimetic knee joint according to claim 1, wherein a first linear slide rail is disposed on the prosthesis frame along an axial direction of the ball screw, and the actuator frame is movably connected to the first linear slide rail.

3. The motor-driven biomimetic knee joint according to claim 2, further comprising:

wherein the spring seat is movably connected to the second linear guide rail.

4. The motor-driven bionic knee joint according to claim 3, wherein the ball screw is connected with the power output shaft through a coupling.

5. The motor-driven biomimetic knee joint according to claim 3 or 4, further comprising:

the bearing seat is fixedly arranged on the artificial limb rack;

a bearing mounted on the bearing housing;

wherein the ball screw is rotatably supported in the bearing.

6. The motor-driven bionic knee joint as claimed in claim 5, wherein the bearing is an angular contact bearing.

7. The motor-driven bionic knee joint according to claim 6, wherein the knee joint extension spring and the knee joint bending spring are both mold springs.

8. The motor-drive based biomimetic knee joint according to claim 7, further comprising:

9. The motor-drive based biomimetic knee joint according to claim 8, further comprising:

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

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