CN103271783B - Artificial limb knee joint with assistance function - Google Patents

Abstract

The invention belongs to the technical field of biomedical engineering and rehabilitation aids, in particular to a prosthetic knee joint with assist function. The upper end of the prosthetic knee joint is connected to the prosthetic receiving cavity, and the lower end is connected to the foot plate through the lower leg connecting rod, the ankle joint and the foot plate. There are three parts: the opening degree control mechanism of the cylinder throttle valve, and the knee joint assisted extension drive mechanism as the active energy supply component of the prosthetic joint. In terms of function, the present invention can realize intelligent active control, good stability, low noise, can adapt to more terrain features, can help amputee patients to sit up autonomously, and independently alternately go up and down stairs, etc., taking into account both passive and active prosthetic knee joints Functional advantage.

Description

A prosthetic knee joint with assist function

technical field

The invention belongs to the technical field of biomedical engineering and rehabilitation aids, and relates to a prosthetic knee joint, in particular to a prosthetic knee joint with power-assisted function driven by a motor to drive a screw and a spring to push a cylinder piston.

Background technique

Thigh prostheses can be divided into two types according to the driving method: one is a passive thigh prosthesis powered by the stump of an amputee patient, and the other is an active thigh prosthesis driven by an external power source for joint flexion and extension. At present, most thigh prostheses on the market are passive, and passive thigh prostheses can be divided into two types: common type and intelligent type. The damping moment of the knee joint of ordinary passive thigh prosthesis is set during installation, and it is difficult to adapt to changes in the external environment such as pace. The intelligent passive thigh prosthesis uses a damper with an adaptive function. When the external environment such as the pace changes, the dynamic adjustment of the damping torque of the prosthetic joint enables the prosthetic side to quickly respond to changes in the gait of the healthy side and the external environment, and has good dynamic performance. Following and gait symmetry. The active thigh prosthesis uses an external power source to provide a stretching moment for the knee joint of the prosthesis to control the flexion and extension of the knee joint of the prosthesis, thus achieving functions that are difficult to achieve with a passive thigh prosthesis, such as being able to stand up without the help of other forces and go up stairs with alternating steps.

Patent US6764520B2 invented a magnetorheological intelligent passive lower limb prosthesis, the core technology of which is the magnetorheological fluid prosthetic knee joint. The joint uses magnetorheological fluid to control the viscosity of the liquid by adjusting the size of the electromagnetic field to achieve adaptive control of the damping torque of the prosthetic knee joint. Patent US201100873391A1 invented a hydraulic cylinder-type intelligent passive lower limb prosthetic knee joint, which uses a micro-motor to adjust the opening size of the hydraulic throttle valve to achieve adaptive control of the damping torque of the prosthetic knee joint. Patent CN101336849A invents a cylinder-fixed four-bar mechanism prosthetic knee joint, which realizes adaptive control of the damping torque of the prosthetic knee joint by adjusting the opening size of the throttle valve through a micro linear motor. Because gas is more compressible than liquid, the prosthetic knee joint of the air cylinder can only control the gait in the swing phase, while the prosthetic knee joint of the hydraulic cylinder can control the gait in the swing phase and the support phase. Patent US20100312363A1 invented an active lower limb prosthetic knee joint with antagonistic and anti-antagonistic muscle functions. The prosthetic knee joint is controlled by two motors to flex and extend the knee joint, which can provide power for the joint movement and realize alternate steps to climb stairs, etc. Function.

In summary, the passive intelligent thigh prosthesis has better gait followability and symmetry when walking on flat ground, and its volume and noise are very small. Active thigh prosthetic joints have a large battery and noise due to the high power of the drive motor.

Contents of the invention

Aiming at the deficiencies in the prior art, the present invention proposes a prosthetic knee joint with power-assisted function, which not only has good gait symmetry and gait followability when the passive intelligent thigh prosthesis walks on flat ground, but also has active prosthetic knee joints. The advantage of being able to alternate between going up stairs and standing up unaided. The invention takes into account the functional advantages of both passive and active prosthetic knee joints, and overcomes the disadvantages of the active thigh prosthesis, such as high energy consumption and high noise.

In order to achieve the above purpose, the technical scheme adopted is:

The upper end of the prosthetic knee joint is connected to the prosthesis receiving cavity, and the lower end is connected to the foot plate through the lower leg connecting rod and the ankle joint. most;

The fixed-cylinder multi-axis prosthetic knee assembly consists of an upper joint body, joint forearm, joint rear arm, cylinder and related parts; the upper joint body is connected to the prosthesis receiving cavity, and the joint , cylinder connection, together form a hinge multi-rod mechanism; a piston and a compressible spring are arranged in the cylinder, and the output end of the piston is a piston pillar, which is connected and fixed with the upper joint body through threads; the piston reciprocates in the cylinder, and then pushes the upper joint body to flex and extend Movement, the piston moves downward, the compressible spring is compressed, storing energy, the piston moves upward, the compressed compressible spring is released, releasing energy, the joint rotates and drives the joint to change from a flexed state to an extended state; the compressible spring is in the The prosthetic component acts as a booster spring;

The opening control mechanism of the throttle valve of the cylinder is composed of a linear motor and a throttle valve; the throttle valve is a needle type throttle valve with a conical valve head inserted into the air inlet of the cylinder; the linear motor pushes the throttle valve to Linear reciprocating motion, the depth of the valve head inserted into the air inlet of the cylinder changes reciprocally, so that the degree of opening and closing of the air inlet changes continuously, and then the damping of the gas is adjusted; the degree of gas damping is related to the opening and closing of the air inlet (outlet) of the cylinder, The larger the opening, the less gas damping, and the smaller the opening, the more gas damping.

The knee joint power-assisted extension driving mechanism includes a DC brushless motor, a gear transmission assembly, a lead screw, and a lower end cover of the cylinder. connected to the output end of the motor to convert the rotational motion of the motor into linear reciprocating motion; the screw nut is connected with the lower end cover of the cylinder through the guide rod. When the brushless DC motor rotates, the screw nut pushes the lower end cover of the cylinder to compress the cylinder A compressible spring, the compressible spring pushes the piston to do linear reciprocating motion in the cylinder, and pushes the upper joint body to move.

The DC brushless motor of the knee joint power-assisted extension drive mechanism adopts Maxon EC30 high-power DC brushless motor.

The piston in the fixed cylinder multi-axis prosthetic knee joint assembly is composed of a piston body, a sealing ring, a piston pillar, a straight piston rod and a bent piston rod; the straight piston rod and the bent piston rod are fixed as a whole through threaded connection or interference fit, The upper end of the piston bent rod is hingedly connected with the piston support.

The beneficial effects of the present invention are:

In the present invention, the fixed cylinder multi-axis prosthetic knee joint assembly is a functional assembly of the prosthetic joint, the air cylinder throttle valve opening control mechanism assembly is an intelligent assembly of the prosthetic joint, and the knee joint assisted extension drive mechanism assembly is an active energy supply assembly for the prosthetic joint. The prosthetic knee joint has distinctive features and complete functions. In terms of function, it can realize intelligent active control, good stability, low noise, and can adapt to more terrain characteristics. It can help amputees sit up autonomously, and alternately go up and down stairs independently. Functional advantages of passive and active prosthetic knee joints.

Description of drawings

Figure 1(a) and Figure 1(b) are respectively the axonometric view and the appearance schematic diagram of the prosthesis of the present invention;

Fig. 2 (a) and Fig. 2 (b) are the front view and side view of the present invention;

Figure 3 is an exploded view of the multi-axis knee joint and related parts of the cylinder;

Figure 4(a) and Figure 4(b) are schematic diagrams of special angles of prosthetic joints;

Fig. 5 is a blast view of the cylinder and its related components;

Figure 6(a) and Figure 6(b) are schematic diagrams of the cylinder throttle valve opening control mechanism components and a partial enlarged view of area A in the figure;

Figure 7(a) and Figure 7(b) are the sectional view and blast view of the drive mechanism assembly of the knee joint assisted extension, respectively;

Explanation of reference signs:

1-Multi-axis knee joint; 2-Cylinder; 3-Joint flexion and extension assist component; 4-Calf end cover component; 5-Cylinder throttle valve opening control mechanism component; 6-Prosthesis receiving cavity; 7-Calf connecting rod; 8 -ankle joint; 9-foot plate; 11-upper joint body; 12-joint forearm; 13-joint rear arm; 14-piston strut; 15-piston bent rod; 16-piston straight rod; Cylinder upper cover; 23-piston; 24-compressible spring; 25-air hole plug; 31-calf chamber; 32-extension motor; Round nut; 37-screw shaft deep groove ball bearing; 41-shank end cover; 42-screw end gear; 43-intermediate wheel; 44-motor end gear; 45-small shaft; 46-gear shaft deep groove ball bearing ;47-Calf end cover bolt; 51-Needle valve; 52-Linear motor; 111-Forearm upper hinge shaft assembly; 112-Rear arm upper hinge shaft assembly; 121-Joint forearm bolt; 141-Piston pillar fixing bolt; Pin shaft; 151-piston bent rod bearing; 211-forearm lower hinge shaft assembly; 212-rear arm lower hinge shaft assembly; 213-end cover positioning bolt; 231-piston bottom bolt; 232-piston X-shaped sealing ring; Piston guide ring; 331-end cover X-shaped sealing ring; 332-end cover guide ring.

Detailed ways

The present invention provides a prosthetic knee joint with power-assisted function. The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The overall structure of the present invention is shown in Figure 1(a) and Figure 1(b), consisting of a multi-axis knee joint 1, a cylinder 2, a joint flexion and extension assist assembly 3, a calf end cover assembly 4, and a cylinder throttle valve opening control mechanism The component 5, the prosthesis receiving chamber 6, the lower leg connecting rod 7, the ankle joint 8 and the foot plate 9 are assembled. Wherein the multi-axis knee joint 1 and the cylinder 2 constitute a fixed-cylinder multi-axis prosthetic knee joint assembly.

Combining Figure 2(a) and Figure 2(b), the upper joint body 11 and the receiving cavity 6 of the prosthesis are fixed together through standard parts, and the receiving cavity is used to be worn on the stump of an amputee patient. and size. The calf end cover 41 is fixedly connected with the calf connecting rod 7 through a specific joint, and the calf connecting rod 7 and the foot plate 9 are hinged together to form the ankle joint 8 . The present invention only provides a schematic view of the receiving cavity 6, the shank connecting rod 7, the ankle joint 8 and the foot plate 9, and the specific structure is not discussed in detail.

The structure of the normal knee joint and leg of the human body is complex. One of the design goals of the prosthesis is to simulate the gait characteristics of the normal joint more realistically. The first condition is to simulate the instantaneous center of motion of the joint. Therefore, the present invention uses a fixed-cylinder multi-axis prosthetic knee joint assembly to realize this function, so that the gait of the prosthesis is closer to the normal gait. The fixed-cylinder multi-axis prosthetic knee joint assembly consists of a multi-axis knee joint 1, a cylinder and its related parts 2.

Compared with the single-axis knee joint, the instantaneous center of motion of the multi-axis knee joint changes in real time. Through this feature, the present invention designs the length of the rod so that it can more realistically simulate the motion of the normal human knee joint. The angle change range of the knee joint of the four-bar mechanism in the present invention is 0°-135°. The height of the instantaneous center of motion is the same as that of the normal knee joint. The multi-axis knee joint 1 (such as a four-bar mechanism knee joint) is mainly composed of an upper joint body 11 , a joint forearm 12 , a joint rear arm 13 and a cylinder block 21 . The upper articulated body 11 and the articulated forearm 12 form a hinge through the forearm upper hinge shaft assembly 111 (a combination of a hollow shaft and a needle bearing), and the articulated forearm bolt 121 passes through the hinge shaft to prevent the articulated forearm from being disengaged from the upper articulated body. The upper articulated body 11 and the articulated rear arm 13 form another hinge of the four-bar mechanism through the upper hinge shaft assembly 112 of the rear arm. The articulated forearm 12 and the articulated rear arm 13 respectively form a hinge with the cylinder block 21 through the lower hinge shaft assembly 211 of the forearm and the lower hinge shaft assembly 212 of the rear arm. The prime mover of the four-bar mechanism is the upper joint body 11, which is connected to the piston assembly in the cylinder through the piston strut 14 fixed on the upper joint body 11 with the piston strut bolt 141. Piston strut 14 and piston bent rod 15 form a hinge by pin shaft 142 and piston bent rod bearing 151, and simultaneously, piston bent rod 15 and piston straight rod 16 also form a hinge by pin shaft 142 and piston bent rod bearing 151. The lower end of the piston straight rod 16 passes through the upper end cover 22 of the cylinder with a circular sealing ring, and is fixedly connected with the piston 23 through the piston bottom bolt 231 . Through the above connection, when the piston 23 moves in the cylinder, it can push the upper joint body 11 to rotate around the hinge, and the cylinder body 21 becomes the frame of the four-bar mechanism, and the upper joint body 11 is the driving element.

The end cover positioning bolt 213 fixes the cylinder upper end cover 22 on the cylinder wall. Use ○-shaped sealing ring for sealing. The piston assembly formed by the fixed connection of the piston 23 and the piston straight rod 16 passes through the central hole of the upper end cover 22 of the cylinder. The compressible spring 24 is placed under the piston 23. In the support phase, the spring compresses and stores energy to maintain the stability of the support phase, and stretches at the end of the support phase to release energy, which plays a power-assisted function in the present invention. Figure 1(b), Figure 4(a) and Figure 4(b) show the schematic diagrams of three special positions of the knee joint rotation: the knee joint angle (the angle between the thigh and the calf) 0°, 90° Schematic diagram of the position at 135° and 135°.

The piston 23 and the cylinder lower end cover 33 need to move in the cylinder, so guidance and dynamic sealing are required. The present invention uses piston X-shaped seal ring 232 for dynamic sealing, piston guide ring 233 for guidance, and air hole plug for sealing the gas path.

An air inlet and an air outlet are respectively arranged on the cylinder wall of the cylinder. Both the air inlet hole and the air outlet hole are elongated small holes, which are designed as through holes in the present invention for the convenience of processing. The hole communicated with the outside world is blocked and sealed with an air hole plug 25 .

A gait cycle can be divided into two phases, the stance phase and the swing phase. The support phase is the process of the foot in contact with the ground, and the swing phase is the process of the calf swinging freely. The support phase is about the first 60% of the entire gait cycle, and the swing phase is the last 40% of the gait cycle. Due to the synergistic effect of multiple groups of muscles in the calf and calf, the rotation of the calf around the thigh is not free rotation, but turns according to a certain law of motion. In order to simulate this special law of motion, the invention realizes the healthy side gait following function through an adjustable gas damping air cylinder throttle valve opening control mechanism assembly. The size of gas damping is related to the degree of opening and closing of the air inlet (outlet) port of the cylinder. The larger the opening, the smaller the gas damping, and the smaller the opening, the greater the gas damping. Figure 5 is an exploded view of the cylinder and its related parts; Figure 6(a) and Figure 6(b) are the schematic diagram of the components of the throttle valve opening control mechanism of the cylinder and the partial enlarged view of area A in the figure. The cylinder throttle valve opening degree control mechanism assembly is composed of a needle valve 51 and a linear motor 52 . The linear motor 52 is screwed into the threaded hole on one side of the cylinder block in the joint assembly by its own thread. The main shaft of the linear motor 52 and the needle valve 51 are fixedly connected together through a formed connection. The partially enlarged sectional view A in FIG. 6 shows the relative positional relationship between the needle valve and the air hole. The linear motor 52 pushes the needle valve 51 forward, the throttle area gradually decreases, and the damping of the cylinder in the joint assembly gradually increases to provide sufficient support force. Cooperating with the position characteristics of the instantaneous center of the multi-axis joint in the joint assembly, the support phase is guaranteed. stability. After the support phase ends, the gait cycle enters the swing phase, the linear motor 52 drives the needle valve 51 to retreat, the throttle area gradually increases, and the damping of the cylinder in the joint assembly gradually decreases, making the knee joint more flexible to rotate. The damping of the knee joint can be adjusted in real time according to the different periods of the stance phase and the swing phase. And the linear motor 52 can adjust the air pressure of the upper and lower chambers of the cylinder in the joint assembly according to the change of walking speed and joint angle. Gradually decrease, that is, when the pace is slow, the linear motor advances, the throttle area gradually decreases, and the damping of the cylinder in the joint assembly gradually increases, so that the knee joint damping can be adjusted in real time according to the pace change to adapt to different speeds. The requirements of the damping force of the knee joint can realize the following function of the healthy side gait.

There are many kinds of human lower limb movements, such as walking on flat ground, going up and down stairs, going up and down ramps, crossing obstacles, sitting up and so on. In order to complete the above-mentioned lower limb movements, the musculoskeletal system of the upper and lower legs needs to provide a certain amount of joint torque and energy for the joints. Due to limb disability, the lower limbs of patients with thigh amputation cannot normally provide joint torque and energy for lower limb movement. During level ground walking, disabled persons wearing the present invention can provide level ground walking gait through lower limb stumps, that is, the lower limb movement of level ground walking can be realized through the prosthetic gait support phase stability component and the prosthetic gait following component. According to the gait analysis of normal people, when the lower limbs complete the movements of going up and down stairs and sitting up without external force, the driving torque and energy required by the joints are far greater than those required for walking on flat ground. At this time, the force provided by the prosthetic gait support phase stability component, the prosthetic gait following component and the stump of the amputee cannot complete the actions of going up and down stairs and sitting up. Therefore, the present invention uses the joint flexion and extension assisting component to provide the extension assisting moment for the prosthesis. The joint flexion and extension assisting component 3 uses an extension assisting motor (brushless DC motor) to indirectly push the piston to realize the assisting function. The extension motor converts the rotary motion into linear motion with the help of the lead screw. The lead screw nut is fixedly connected with the lower end cover of the cylinder, and the upward movement of the spring and the piston can play the role of assisting stretching. For example, when an amputee wears the present invention and sits on a chair, the angle of the knee joint is 90 degrees, and the piston is at the bottom of the cylinder. The upward movement of the cover indirectly pushes the piston upward. Due to the setting of the rod length of the four-bar mechanism, the knee joint angle trajectory will gradually change from 90 degrees to 0 degrees. When the knee joint angle becomes 0 degrees, the amputee will be in a standing state , the motor reverses, and the lower cover of the cylinder returns to its original position. When going up and down stairs alternately, the method of assisting stretching is the same as sitting up, so I won’t repeat it here.

As shown in Fig. 7(a) and Fig. 7(b), the output shaft of the extension-assist motor 32 with its own reducer and the gear 44 at the motor end are fixedly connected together through a formed connection and threaded pins. The intermediate wheel 43 and the shank end cover 41 are connected together by the gear deep groove ball bearing 46 and the small shaft 45, and the intermediate wheel 43 is meshed with the motor end gear 44. The lead screw 34 and the lead screw end gear 42 are fixedly connected together by forming connection, and mesh with the intermediate wheel 43 . The top of the leading screw 34 is connected to the top of the shank chamber 31 by the deep groove ball bearing 37 of the leading screw shaft, and three of the gears are gears of the same specification. The round nut 36 is sleeved on the lead screw, and through the 120° evenly distributed lead screw guide rod 35, passes through the smooth small hole at the upper end of the calf cavity 31 and is fixedly connected with the lower end cover 33 of the cylinder, and the DC brushless motor drives the lead screw 34 to rotate, Lead screw 34 just drives round nut 36 and cylinder lower end cover 33 to form slide block, linear reciprocating motion in the cylinder in joint assembly, promotes the piston 23 in joint assembly to move up and down, realizes the prosthetic extension assisting function. Since the stretching assisting component is only used for stretching assisting and does not work continuously, it has the advantages of low energy consumption and low noise.

The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Those of ordinary skill in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all Equivalent technical solutions also belong to the category of the present invention, and the scope of patent protection of the present invention should be defined by the claims.

Claims (3)

1. one kind has the artificial limb knee-joint of assist function, upper end is connected with artificial limb reception cavity, lower end is connected with sole by shank connecting rod, ankle joint, it is characterized in that, comprise fixing cylinder multiaxis artificial limb knee-joint assembly, cylinder throttle valve opening controlling organization, knee joint power-assisted stretching, extension driving mechanism three parts;

Described fixing cylinder multiaxis artificial limb knee-joint assembly is made up of upper joint body, joint forearm, rear joint arm, cylinder and related components; Upper joint body is connected with artificial limb reception cavity, and joint forearm and rear joint arm are connected with upper joint body, cylinder respectively, common composition hinge multi-bar linkage; Arrange piston and compressible spring in cylinder, the outfan of piston is piston pillar, is connected and fixed by screw thread and upper joint body; Piston moves back and forth in the cylinder, and then promotes upper joint body flexion and extension, and piston moves downward, compressible spring is compressed, storage power, piston upwards, compacted compressible spring is released, and releases energy, and articulation is also with movable joint to become extended configuration from flexion;

Described cylinder throttle valve opening controlling organization is made up of linear electric motors and choke valve; Choke valve is needle-type throttle valve, and its head portion is conical, inserts in cylinder air inlet; Linear electric motors promote choke valve and carry out straight reciprocating motion, and the degree of depth that valve head inserts cylinder air inlet back and forth changes, and the folding degree of air inlet is constantly changed, and then the damping size of adjustments of gas;

Described knee joint power-assisted stretches driving mechanism and comprises DC brushless motor, gear-driven assembly, leading screw, cylinder bottom end cover, and knee joint power-assisted is stretched driving mechanism lower end and is connected with shank connecting rod, for artificial limb provides external force by shank end-cap assembly; Leading screw is connected with the outfan of DC brushless motor, and the rotary motion of motor is converted to straight reciprocating motion; Feed screw nut is connected as a single entity by guide post and cylinder bottom end cover, when DC brushless motor, feed screw nut promotes cylinder bottom end cover, and then the compressible spring in compression cylinder, compressible spring promotes piston and does straight reciprocating motion in the cylinder, promotes upper joint body motion.

2. a kind of artificial limb knee-joint with assist function according to claim 1, is characterized in that, the DC brushless motor that described knee joint power-assisted stretches driving mechanism adopts Maxon EC30 high power DC brushless motor.

3. a kind of artificial limb knee-joint with assist function according to claim 1, is characterized in that, the piston in described fixing cylinder multiaxis artificial limb knee-joint assembly is made up of piston body, sealing ring, piston pillar, straight rod piston and piston knee; Straight rod piston and piston knee are threaded connection or interference fit is fixed as one, and upper end and the piston support column type of piston knee are in the hinge connection.