JP2012235882A - Leg-mounted device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leg-mounted device that has a good weight balance when viewed from in a roll direction, and prevents a leg from deviating inward when the leg is gotten up.SOLUTION: The leg-mounted device 100 is used for rocking the leg of a user. The device 100 includes a thigh link 2 and a lower thigh link 12, which are mounted to the thigh and lower thigh of the user, respectively. The lower thigh link 12 is connected rockably to the thigh link 2. A motor 3, which is arranged on a lateral outside of the leg for rocking the lower thigh link 12, is attached to the thigh link 2. A counter weight 30 is attached to a lateral inside of the leg of the lower thigh link 12. The counter weight 30 offsets a moment MT1 of the leg-mounted device, the moment being generated due to the weight of the motor 3 around a roll axis at a groin.

Description

  The present invention relates to a leg brace that assists the movement of a user's leg.

  In addition to the conventionally known long leg braces, leg braces that actively move the lower leg with an actuator have been studied in recent years. Leg braces having actuators have various names such as “powered suit” and “walking assist (support) device”. In this specification, such devices will be collectively referred to as “leg braces”.

  An example of a leg brace provided with an actuator is disclosed in Patent Document 1. In the device, a motor applies torque to the leg joint to support leg movement. The motor is positioned on the side of the user's hip joint and knee joint when the user wears the leg brace (in the lateral direction of the user and laterally outward with respect to the knee joint).

  Here, terms relating to coordinate axes used in this specification will be described. The pitch axis means an axis that faces the body side direction (lateral direction) of the user. The roll axis means an axis that faces in the front-rear direction when the user takes an upright posture. The yaw axis means an axis that faces the longitudinal direction of the user's trunk when the user takes an upright posture. In other words, the yaw axis means the axis that faces in the vertical direction. The “pitch axis”, “roll axis”, and “yaw axis” are defined with reference to a coordinate system fixed to the user. For example, the yaw axis of the lower leg corresponds to a center line extending in the longitudinal direction of the lower leg. The yaw axis of the foot is orthogonal to the sole of the foot and corresponds to a straight line passing through the rotation axis of the ankle joint. In this specification, the roll axis, pitch axis, and yaw axis based on the user wearing the leg brace are referred to as the roll axis, pitch axis, and yaw axis of the leg brace. As used herein, the terms “pitch axis”, “roll axis”, and “yaw axis” are used interchangeably with terms commonly used in robotics.

JP 2002-301124 A

  When the motor which increases in weight is disposed on the side of the leg, the weight balance of the leg brace when viewed from the roll direction (front of the user) is poor. In particular, when a heavy object such as an actuator is disposed on the laterally outer side of the leg, when the foot is lifted, the tip of the foot is moved inward due to the weight of the actuator or the like. If the tip of the free leg during walking approaches the inside, there is a risk of being caught by the other leg. The present specification provides a leg brace that has a good weight balance when viewed from the roll direction (in front of the user), and that prevents the foot from moving inward when the foot is lifted.

  The leg orthosis disclosed in this specification includes a thigh link, a crus link, and an actuator. The thigh link is attached to the user's thigh. The lower leg link is swingably connected to the thigh link and is attached to the user's lower leg. The actuator is disposed laterally outside the leg. The actuator swings the lower leg link. The leg brace further comprises balance means for canceling out the moment around the roll axis at the base of the leg due to the weight of the actuator.

  One aspect of the balancing means is a counterweight attached to the thigh link or the lower leg link on the inner side in the lateral direction of the user's leg. The counterweight may be a simple weight, but it is preferable to use a controller that controls the actuator and / or a battery that supplies power to the actuator as the counterweight.

  The balance means may be realized by a component called a counterweight, but can also be realized by devising the structure of the thigh link or the thigh link itself. That is, one of the thigh link and the crus link has a frame extending along the leg on the inner side and the outer side in the lateral direction of the leg, and the balance means is made by making the weight of the inner frame heavier than the outer frame. Can also be realized. To make the weight of the inner frame heavier than the weight of the outer frame, the inner frame may be made larger (thicker) than the outer frame. This may be realized by using a material having a density higher than that of the frame. For example, a titanium alloy having a low density may be used for the outer frame, and stainless steel or iron having a higher density than the titanium alloy may be used for the inner frame. Alternatively, it is also preferable to use CFRP (carbon fiber reinforced plastic) as a low density material.

  The above method is to adjust the balance of moments around the roll axis at the base of the leg. In addition to such a method, it is also preferable that the balancing means is realized by a support member that suspends the actuator from the user's waist. This approach has the advantage of no special weight gain for balancing.

It is a perspective view of the leg orthosis of 1st Example. It is a front view of the leg orthosis of 1st Example. It is a front view of the leg orthosis of 2nd Example. It is a front view of the leg orthosis of 3rd Example.

  A leg brace 100 of the first embodiment will be described with reference to the drawings. FIG. 1 is a schematic perspective view of a leg brace 100 worn by the user H. FIG. 2 shows a front view of the leg brace 100 worn by the user H. FIG. In this embodiment, the leg brace 100 is attached to the right leg of the user H. The leg brace 100 assists the walking motion by applying torque to the user's right knee joint. The leg brace 100 has a multi-link structure constituted by the thigh link 2, the crus link 12, and the foot link 22.

  The coordinate system shown in the figure will be described. In the XYZ coordinate system shown in the figure, the X axis corresponds to the roll axis, the Y axis corresponds to the pitch axis, and the Z axis corresponds to the yaw axis. The roll axis (X axis) corresponds to the front-rear direction when the user H takes an upright posture, the pitch axis (Y axis) corresponds to the lateral direction (side) of the user, and the yaw axis (Z axis). Corresponds to a vertical direction (vertical direction) when the user H takes an upright posture. The method of taking this coordinate system is common to all the subsequent drawings.

  The thigh link 2 is attached to the thigh of the user H. A motor 3 is attached to the thigh link 2. Note that a controller unit 4 for controlling the motor 3 and a sensor for measuring a rotation angle of the lower leg link are also arranged in the cover of the motor 3. The motor 3 is fixed to the thigh link 2 so as to be positioned on the outer side in the lateral direction of the leg.

  The lower leg link 12 is disposed along the lower leg of the user H. The lower leg link 12 includes main frames 13a and 13b located on both lateral sides of the lower leg of the user H, and a connecting bar 11 that connects the left and right main frames. A counterweight 30 is attached with bolts 31 to the main frame 13a located inside the legs. The counterweight 30 is attached to cancel the moment generated around the roll axis at the base of the leg due to the weight of the motor 3. The counterweight 30 will be described in detail later.

  The lower leg link 12 is connected to the thigh link 2 so as to be swingable by knee joints 5a and 5b. The knee joints 5a and 5b are positioned coaxially with the rotation axis that faces the pitch axis (Y-axis in the figure) direction of the knee joint of the user H.

  The motor 3 is connected to a knee joint 5b located outside the user's right knee side. By driving the motor 3, the crus link 12 swings around the pitch axis with respect to the thigh link 2. The leg brace 100 swings the crus link 12 around the pitch axis in accordance with the walking motion, applies torque to the right knee joint of the user H, and assists the walking motion. The motor 3 is controlled by a controller unit 4 disposed in the case. The controller unit 4 controls the swinging of the crus link 12 so as to synchronize with the user's walking motion. A description of the control algorithm for walking support is omitted.

  The foot link 22 is fixed to the foot of the user H. The foot link 22 has a sole 26 fixed to the sole of the user and frames 24 a and 24 b extending from both sides of the sole 26. Although illustration is omitted, shoes are attached on the sole 26, and the foot link 22 is fixed to the user's feet by the shoes.

  The foot link 22 is connected to the crus link 12 through a pair of ankle joints 28a and 28b. Specifically, the frame 24a of the foot link 22 is connected to the main frame 13a of the crus link 12 through the ankle joint 28a inside the user's ankle. The frame 24b of the foot link 22 is connected to the main frame 13b of the crus link 12 via the ankle joint 28b outside the ankle. The ankle joints 28a and 28b allow the foot link 22 to rotate around the pitch axis with respect to the crus link 12. The ankle joint 28b located outside the ankle incorporates an angle sensor that measures the angle of the foot link 22 with respect to the crus link 12.

  FIG. 2 is a view of the leg brace 100 attached to the right leg HR of the user H as seen from the roll axis direction (front of the user). The straight line indicated by the reference sign CL is the center line of the right leg when viewed from the roll axis direction. The symbol MP is the center of rotation around the roll axis of the leg at the base of the leg. Symbols MT1 and MT2 represent moment components around the rotation center MP that the leg orthosis 100 exerts on the leg. MT1 indicates a moment component caused by the motor 3, and MT2 indicates a moment component caused by the counterweight 30.

  As shown in FIG. 2, the motor 3 protrudes outward in the lateral direction of the leg. The motor 3 is heavy. Due to the weight of the motor 3, a moment MT1 counterclockwise on the roll axis is generated at the base MP of the leg. On the other hand, the counterweight 30 is disposed inside the legs in the lateral direction. The direction of the moment MT2 about the roll axis of the leg base MP due to the weight of the counterweight 30 is clockwise. The weight of the counterweight 30 is selected so that the moment MT2 cancels the moment MT1. Therefore, the leg brace 100 generates almost no moment around the leg root MP roll axis. Therefore, even when the user raises the right leg, the toes do not come to the left or right. The leg brace 100 has a good balance when viewed from the roll axis direction, and the leg brace 100 does not swing the toe left or right when the user raises the foot. Therefore, the user can walk smoothly while wearing the leg brace 100.

  The counterweight 30 may be a lump of metal, but may include a controller that controls the motor 3 and sensors and / or a battery that supplies power to the motor 3.

In FIG. 3, the front view of the leg orthosis 200 of 2nd Example is shown. Unlike the leg brace 100 of the first embodiment, the leg brace 200 of the second embodiment does not include a counterweight. Instead, in the leg brace 200, the main frame 213a on the inner side of the lower leg link 212 is made of a material different from that of the outer main frame 213b. The outer main frame 213b is made of CFRP (carbon fiber reinforced plastic), and the inner main frame 213a is made of stainless steel. In FIG. 3, the gray hatching attached to the inner main frame 213a represents a difference in material from the outer main frame 213b. The density of CFRP is approximately 1.5 to 1.7 g / cm ³ . On the other hand, the density of stainless steel is approximately 7.7 to 7.9 g / cm ³ . Since the density is greatly different, the inner main frame 213a is much heavier than the outer main frame 213b even if the sizes are almost the same. This difference in weight generates a moment MT2 in the clockwise direction of the roll axis of the leg base MP. This moment MT2 cancels out the moment MT1 caused by the weight of the motor 3. As a result, the leg brace 200 according to the second embodiment has a good balance when viewed from the roll axis direction, as in the leg brace 100 according to the first embodiment. Or do not shake to the right.

  In the second embodiment, a material having a higher density than the material of the outer main frame 213b was selected as the material of the crus link inner main frame 213a. The inner main frame may be heavier than the outer main frame without changing the density. For example, the inner main frame can be made heavier than the outer main frame by making the inner main frame thicker than the outer main frame.

  In FIG. 4, the front view of the leg orthosis 300 of 3rd Example is shown. The leg brace 300 of the third embodiment does not include the counterweight 30 of the leg brace 100 of the first embodiment. Others include all the parts of the leg brace 100 of the first embodiment. The leg brace 300 of the third embodiment further includes a waist belt 40 to be worn on the user's waist and a suspension belt 42 extending from the waist belt 40. The lower end of the suspension belt 42 is connected to the motor 3. The suspension belt 42 suspends and supports the motor 3 including the controller unit 4 from the waist. Since the motor 3 which is heavy is supported by the suspension belt 42, no moment is generated around the base MP of the leg. The leg brace 300 of the third embodiment balances moments around the roll axis of the leg root MP by means (suspending belt 42) different from the leg braces of the first and second embodiments. Similarly to the leg orthosis of the first and second embodiments, the leg orthosis 300 of the third embodiment has a good balance when viewed from the roll axis direction, and the leg orthosis 100 moves the foot to the left when the user raises the foot. Or do not shake to the right.

  Since the motor 3 is located outside the knee joint, when the right leg is swung, the motor 3 draws an arc around the pitch axis with the upper end of the suspension belt 42 as the center. Therefore, the suspension belt 42 does not loosen even during a leg swing, and always supports the motor 3.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Thigh link 3: Motor 4: Controller 5a, 5b: Knee joint 11: Connection bar 12: Lower leg link 13a, 12b: Main frame 22: Foot link 24a, 24b: Frame 26: Sole 28a, 28b: Ankle joint 30: Counterweight 40: waist belt 42: suspension belts 100, 200, 300: leg brace 212: lower leg links 213a, 212b: main frame

Claims (6)

Leg brace that swings the user's leg,
A thigh link attached to the user's thigh;
A thigh link that is swingably connected to the thigh link and is attached to the user's thigh,
An actuator that is arranged laterally outside the leg and swings the lower leg link;
A balancing means for canceling the moment generated around the roll axis at the base of the leg due to the weight of the actuator;
A leg brace characterized by comprising:   The leg brace according to claim 1, wherein the balance means is a counterweight attached to the thigh link or the lower thigh link on the inner side in the lateral direction of the user's leg.   The leg weight according to claim 2, wherein the counterweight includes a controller that controls the actuator and / or a battery that supplies electric power to the actuator.   One of the thigh link and the lower thigh link has a frame extending along the leg on the inner side and the outer side in the lateral direction of the leg, and the weight of the inner frame is heavier than the weight of the outer frame. The leg orthosis according to claim 1.   The leg brace according to claim 4, wherein the density of the material of the inner frame is higher than the density of the outer frame.   The leg brace according to claim 1, wherein the balance means is a support member that suspends the actuator from the waist of the user.

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