JP2021029596A - Knee joint assist device - Google Patents

Abstract

To provide a knee joint assist device which is light-weight and can be applied for various uses while being well compatible to the roll back motion of a knee joint.SOLUTION: A knee joint assist device 10 comprises: a body 12, 14; a fixed gear 24 including a linear gear portion 26 extending along a straight line and a sector gear portion 28 extending along a circular arc in contact with the straight line; a moving gear 20 engaged with the fixed gear; a first arm member 16 which is attached to the moving gear and moves with the moving gear along the fixed gear; and a second arm member 18 fixed to the body. The first arm member is fixed to a thigh of a wearing person, and the second arm member is fixed to a cruris of the wearing person.SELECTED DRAWING: Figure 1

Description

The present invention relates to a knee joint assisting device that assists human walking and knee flexion / extension movements.

Various knee joint assist devices have been developed to assist the wearer in walking and bending / stretching exercises during daily or rehabilitation. For example, in Patent Document 1, an upper arm and a lower arm that are relatively rotatably supported around a support shaft are attached to the thigh and lower leg of the wearer, and the upper arm is swiveled beyond a predetermined angle position. A knee wearer with a stopper on the lower arm to prevent movement is described. The knee fitting of Patent Document 1 cannot follow the sliding or rolling motion or rollback motion of the knee joint (see, for example, Non-Patent Document 2), and hinders the walking motion or the bending and stretching motion.

In this regard, Patent Document 2 describes a knee joint exercise assisting device suitable for the sliding and rolling motion of the knee joint so that the knee joint side end portion of the lower leg mounting portion can slide in the anteroposterior direction. However, the knee joint movement assisting device of Patent Document 2 is provided with a power transmission device including a motor as a power source, spur gears and immediate bevel gears, and a battery, and the device has to be heavy, and rehabilitation support is provided. , Assistance work support, nursing work support, agricultural work support, etc. There is a problem that it is difficult to apply it to people with severe disabilities.

Non-Patent Document 1 discloses a knee joint assist orthosis for walking rehabilitation using an electromagnetic motor, a non-circular gear, and a groove cam. The knee joint assist orthosis of Non-Patent Document 1 is also suitable for the sliding or rolling motion of the knee joint, but it is equipped with a heavy object such as an electromagnetic motor or a battery, and the orthosis itself is heavy. As in the case, there is a problem that it is difficult to apply it to various uses, especially to a person with severe disability.

Japanese Unexamined Patent Publication No. 2008-272312 Japanese Unexamined Patent Publication No. 2010-063581

Terada H. et al .: Development of a knee motion assist mechanism for wearable robot with a non-circular gear and grooved cams, Mechanisms, Transmissions and Applications: Mechanism and Machine Science, 3, Springer, pp. 68, 2012. Functional evaluation of living knee joints in squat motion using X-ray motion image simulation based on CT images, Proceedings of the Japan Society of Mechanical Engineers (C) Vol. 77, No. 782, pp.219-227, 2011

An object of the present invention is to solve the problems of the prior art, and to provide a lightweight knee joint assisting device that can be applied to various applications while better adapting to the rollback movement of the knee joint. It is said.

According to the present invention, a fixed gear having a main body, a linear gear portion extending along a straight line, and a sector gear portion extending along an arc in contact with the straight line, and a fixed gear arranged in the main body, and the inside of the main body. A moving gear that is disposed in and engages with the fixed gear, a first arm member that is attached to the moving gear and moves with the moving gear along the fixed gear, and a second arm member fixed to the main body. The knee joint assisting device is provided with the above-mentioned arm member, the first arm member is fixed to the wearer's thigh, and the second arm member is fixed to the wearer's lower leg. Provided.

The present invention can be applied to a wide variety of applications due to its simple structure and light weight, while being able to reproduce a motion very similar to the rollback motion of a human knee joint.

It is a schematic schematic diagram of the knee joint assist device according to the preferred embodiment of the present invention. It is a schematic diagram which shows the knee joint assisting device of FIG. 1 attached to the knee joint of the user together with the user. It is a schematic diagram which shows the guide groove of the knee joint assist device of FIG. It is a side view for demonstrating the operation position of the 1st arm member with respect to the main body of the knee joint assisting device of FIG. It is a side view for demonstrating the operation position of the 1st arm member with respect to the main body of the knee joint assisting device of FIG. It is a side view for demonstrating the operation position of the 1st arm member with respect to the main body of the knee joint assisting device of FIG. Based on the measurement result of the displacement of the rotation axis of the joint assist device produced by the present invention, the movement of the center of the knee is performed based on the analysis result of the movement of the knee joint when the wearer (subject) squats by the X-ray image. It is a graph which shows together with the knee joint motion model created by linear approximation. It is a schematic diagram which shows the motion model of the knee joint assist device of FIG.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
In FIG. 1, the knee joint assisting device 10 according to the present embodiment has a main body portion 12 and 14 composed of two plate-shaped members arranged in parallel and a fixed gear 24 fixed between the main body portions 12 and 14. A moving gear 20 that engages with the fixed gear 24, a torsion coil spring or torsion spring 32 as an urging means arranged between the main bodies 12 and 14, and a rotating shaft 22 of the moving gear 20. A first arm member 16 and a second arm member 18 fixed to the main body portions 12 and 14 are provided as main components. Guide grooves 12a and 14a are formed in the main bodies 12 and 14.

As shown in FIG. 2, the knee joint assisting device 10 includes an upper thigh fitting 40 attached to the first arm member 16 and a lower leg fitting 42 attached to the second arm member 18. Have. The upper leg fitting 40 can be formed of an elastomer, plastic, leather, cloth, or the like that is compatible with the surface of the human thigh, and the upper leg fitting 40 can be attached to the outer side surface of the human thigh. It has a band 40a to be fixed. The lower leg fitting 42 can be formed of an elastomer, plastic, leather, cloth, or the like that is compatible with the surface of the human lower leg, and the lower leg fitting 42 can be attached to the outer side surface of the human lower leg. It has a band 42a to be fixed.

The knee joint assisting device 10 is mounted on the outer side surface of the wearer's knee joint so that the rotation axis 22 of the moving gear 20 substantially coincides with the rotation axis of the wearer's knee joint in the standing posture. At this time, the first arm member 16 projects upward, the second arm member 18 projects downward, and preferably the first and second arm members 16 and 18 are arranged in a straight line. The main bodies 12 and 14 of the knee joint assisting device 10 themselves are not fixed to the wearer's knee joint.

The fixed gear 24 has a main body portion 24a made of a rectangular plate-shaped member. The main body portion 24a has a fan-shaped portion 24b that bulges from one of the measuring edges of the main body portion 24a. The fixed gear 24 has teeth along the outer peripheral surface of the fan-shaped portion 24b so as to connect the linear gear portion 26 geared along the upper edge portion of the main body portion 24a in the tangential direction from one end of the linear gear portion 26. It has a cut sector gear portion 28. More specifically, the linear gear portion 26 and the sector gear portion 28 are arranged so that the pitch line of the linear gear portion 26 is in contact with the pitch circle of the sector gear portion 28. When the knee joint assisting device 10 is attached to the lateral side surface of the knee joint of a user in an upright posture, the pitch line of the linear gear portion 26 extends substantially in the horizontal direction. Further, the sector gear portion 28 is arranged so as to face the rear of the user when the knee joint assisting device 10 is attached to the knee joint of the user.

The guide grooves 12a and 14a formed in each of the plate members forming the main bodies 12 and 14 are formed along the circumference of at least the center Os of the pitch circle of the sector gear portion 28 of the fixed gear 24. , 14b and straight portions 12c and 14c extending parallel to the pitch line of the linear gear portion 26 of the fixed gear 24 from the upper ends of the arc portions 12b and 14b.

The moving gear 20 has teeth that engage with the teeth of the linear gear portion 26 and the sector gear portion 28 of the fixed gear 24. The moving gear 20 can be a circular gear like a normal spur gear, but the portion engaged with the linear gear portion 26 of the fixed gear 24 and the portion engaged with the sector gear portion 28 have different radii. May be good. The moving gear 20 rotates about a rotation shaft 22 extending perpendicularly to the plate members forming the main bodies 12 and 14. The moving gear 20 is rotatable together with the rotating shaft 22 or relative to the rotating shaft 22. Rollers or followers 22a that engage with the guide grooves 12a and 14a can be attached to both ends of the rotating shaft 22. In this way, the moving gear 20 can move along the guide grooves 12a and 14a while rotating around the rotating shaft 22.

The torsion spring 32 is attached to a boss portion 30 as a torsion spring attachment portion fixed to the inner surfaces of the main body portions 12 and 14. The torsion spring 32 has first and second legs 32a and 32b. When the torsion spring 32 is attached to the boss portion 30, the first leg portion 32a engages with the rotating shaft 22 of the moving gear 20 or the roller or follower 22a attached to the rotating shaft 22. The second leg portion 32b is fixed to the torsion spring mooring portion 34 arranged in the vicinity of the second arm member 18.

As shown in FIG. 3, the first arm member 16 is located at a position (0 ° position) at which the central axis Om of the first arm member 16 is substantially aligned with the central axis O of the second arm member 18. ) To the position where the central axis Om makes an angle of 90 ° with respect to the central axis O (FIG. 4), and the position where the central axis Om makes an angle of 150 ° with respect to the central axis O (FIG. 5). It can be moved with respect to the main bodies 12 and 14.

During this time, the torsion spring 32 urges the rotating shaft 22 of the moving gear 20 in the direction of returning to the 0 ° position. The urging force from the torsion spring 32 to the rotating shaft 22 gradually increases as the angle increases. That is, the urging force from the torsion spring 32 to the rotation shaft 22 is greatest when the wearer wearing the knee joint assisting device 10 bends the deepest, and when the knee is extended from such a posture, the wearer's knee It is possible to assist the extension movement satisfactorily.

FIG. 6 shows a linear approximation of the movement of the center of the knee based on the analysis result of the movement of the knee joint when the wearer (subject) squats by the X-ray image of the knee joint performed by Yoshitaka Shiraishi and others. The created knee joint movement model is shown. Knee flexion / extension movement, also called rollback motion, is a combined movement of rolling and sliding movements of the femur on the tibia, and the femur is in contact with the tibia from the fully extended position to the initial stage of flexion. It is only a rolling motion that rotates, but a sliding motion is gradually added, and finally it becomes only a sliding motion.

In the present embodiment, the dimensions of the knee joint assisting device 10 are determined so that the rotating shaft 22 of the moving gear 20 can move along the model of FIG. 6 as much as possible. With reference to FIG. 7, a motion model of the knee joint assisting device 10 is shown. In FIG. 7, the movement of the rotating shaft 22 is indicated by an alternate long and short dash line. Further, in FIG. 7, the X-axis is the front-rear direction (the left side is the front of the wearer), and the Z-axis is the up-down direction.

r1 is the radius of the portion 1 of the moving gear 20 that engages the linear gear portion 26 (2 in FIG. 7) of the fixed gear 24, and r2 is the radius of the portion 3 that engages the sector gear portion 28 (4 in FIG. 7). It is a radius, and r3 is the radius of the sector gear portion 4. θ1 is the center angle of the portion 1 with respect to the center Omg of the rotating shaft 22 of the moving gear 20, and θ2 is the center angle of the portion 2 with respect to the center Omg of the rotating shaft 22 of the moving gear 20.

The knee joint assisting device 10 was actually manufactured with r1 = r2 = 12 mm, r3 = 8 mm, θ1 = 30 °, and θ2 = 120, and the operation of the rotating shaft 22 was measured. The measurement result is shown by a alternate long and short dash line in FIG. As can be understood from FIG. 6, the knee joint assisting device 10 according to the present embodiment can reproduce a movement very close to the rollback movement of the human knee joint shown by the solid line.

10 Knee joint assist device 12 Main body 12a Guide groove 12b Arc part 12c Straight part 14 Main body 14a Guide groove 14b Arc part 14c Straight part 16 First arm member 18 Second arm member 20 Moving gear 22 Rotating shaft 22a Follower 24 Fixed gear 24a Main body part 24b Fan-shaped part 26 Straight gear part 28 Sector gear part 30 Boss part 32a First leg part 32b Second leg part 34 Mooring part 40 Upper leg attachment 40a Band 42 Lower leg attachment 42a Band

Claims (5)

With the main body
A fixed gear having a linear gear portion extending along a straight line and a sector gear portion extending along an arc in contact with the straight line, and a fixed gear arranged in the main body.
A moving gear disposed in the main body and engaged with the fixed gear,
A first arm member attached to the moving gear and moving along with the moving gear along the fixed gear.
A second arm member fixed to the main body is provided.
A knee joint assisting device in which the first arm member is fixed to the thigh of the wearer and the second arm member is fixed to the lower leg of the wearer. The main body is formed with a guide groove that guides the rotation axis of the moving gear in a direction parallel to the linear gear portion of the fixed gear and along an arc centered on the center of the sector gear portion. Item 1. The knee joint assisting device according to item 1. The knee joint assisting device according to claim 2, further comprising an urging means for urging the rotating shaft of the moving gear toward a straight portion of the guide groove. The knee joint assisting device according to claim 3, wherein the urging means is a torsion spring having a leg portion that engages with the rotating shaft of the moving gear. The upper leg fitting attached to the first arm member and the lower leg fitting attached to the second arm member are further provided, and the upper leg fitting 40 is of the wearer. The knee joint assisting device according to claim 4, wherein the lower leg attachment is fixed to the outer side surface of the thigh and is fixed to the outer side surface of the wearer's lower leg.

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