JP2011193899A - Lower-extremity orthotic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lower-extremity orthotic capable of changing the neutral swinging angle according to the state of feet during the walking motion.SOLUTION: The lower-extremity orthotic 10 includes a lower-thigh member 12, a foot member 14, a coil spring 22 and an adjusting part 20 capable of changing the neutral swinging angle of the coil spring. The adjusting part 20 changes a neutral swinging angle while the foot member 14 is grounded to a plantar flexion side from a neutral swinging angle while the foot member 14 is not grounded. The lower-extremity orthotic 10 can increase the spring restitutive force applied in the direction of suppressing the swing of the lower thigh (the direction of plantar-flexing the foot) when the lower thigh of an erected leg swings forward around the foot (when the foot is dorsiflexed) by changing the neutral swinging angle to the plantar flexion side.

Description

  The present invention relates to a lower limb orthosis that assists ankle movement.

  As an auxiliary device for a user who cannot freely move his / her foot, a lower limb orthosis (also referred to as AFO: Angle Foot Orthosis) is known. The lower limb orthosis includes a leg member fixed to the user's lower leg and a foot member fixed to the foot. As used herein, “lower leg” means a portion between a knee and an ankle. “Foot” means a portion ahead of the ankle joint. In some lower limb orthoses, a leg member is swingably connected to the lower leg member, and a spring and / or a damper is connected between the lower leg member and the foot member. Dampers and springs reduce the load on the ankle during walking. An example of a lower limb orthosis is disclosed in Patent Document 1.

Japanese Patent No. 4156909

  Since the lower limb orthosis disclosed in Patent Document 1 is adapted to individual users, the swing angle of the foot member relative to the lower leg member when the spring has a natural length can be changed. Specifically, the length of the rod connected to the end portion of the spring can be changed by a screw type adjuster at the end portion.

  Hereinafter, the angle formed by the leg member and the foot member when the spring has a natural length may be referred to as a “neutral swing angle”. Further, hereinafter, in this specification, “swing angle” is defined as follows. The “swing angle” is a leg member reference line that is perpendicular to the swing axis of the lower leg member and the foot member and extends parallel to the lower leg, and a foot member reference that is perpendicular to the swing axis and extends parallel to the sole. Represents the angle between the line. That is, the swing angle of the foot member is equivalent to the swing angle of the user's foot. Speaking flatly, the “swing angle” corresponds to an angle measured from the lower leg (shin) toward the instep. The magnitude of the swing angle is expressed as an angle from the crus member reference line toward the foot member reference line. That is, the case where the lower leg member reference line and the foot member reference line are orthogonal to each other is set to 90 degrees. When the foot swings toward the lower leg, the angle decreases from 90 degrees, and the toe swings toward the lower side. Is expressed as increasing from 90 degrees. Note that swinging of the foot in a direction in which the toes approach the lower leg is called “dorsiflexion”, and swinging of the foot so that the toes are lowered is called “bottom flexion”.

  Further, in this specification, the inclination (that is, the swing angle) of the foot member with respect to the crus member may be referred to as “the position of the foot member” for easy understanding. Further, the position of the foot member when the angle formed by the leg member and the foot member is a neutral swing angle may be referred to as a “neutral position”.

  In the case of a lower limb orthosis including a spring, when the foot member is in the neutral position, the restoring force of the spring is not applied to the foot member. On the other hand, when the foot member is in a position other than the neutral position, the restoring force of the spring is applied to the foot member in a direction to return to the neutral position. That is, when the user wearing the lower limb orthosis of Patent Document 1 loosens the force of the ankle, the foot member returns to the neutral position by the restoring force of the spring and is held at the neutral position. As described above, when the lower limb orthosis of Patent Document 1 is used, each user can manually adjust the neutral swing angle according to his / her preference or ankle structure.

  However, according to the study of the inventor, it has been found that when the state of the foot during the walking motion changes, the preferred neutral swing angle also changes. A lower limb orthosis that can change the neutral swing angle in accordance with the state of the foot during the walking motion is desired.

  As a result of the inventor's detailed analysis of the walking motion of a healthy person, it has been found that the functions required of the ankle joint differ between the swinging leg and the standing leg. In other words, the ankle joint functions to bend the foot so that the toe of the swinging foot does not contact the ground during swinging. On the other hand, when standing, the ankle joint functions to support the weight of the pedestrian and to prevent the forward movement of the body from becoming too fast, i.e., the speed at which the foot is bent back from becoming too fast. . If the ankle joint is disabled, the ankle joint cannot sufficiently perform the above functions. Therefore, the lower limb orthosis assists the dorsiflexion of the foot so that the toes are directed upward during the swinging leg, and faces the plantar flexion direction so that the dorsiflexion of the foot associated with the forward movement of the body does not become too fast during the standing leg It is preferable that the foot can be urged (resistance is added to swinging in the dorsiflexion direction of the foot).

  The technology disclosed in the present specification is embodied as a lower limb orthosis including a leg member, a foot member, an elastic body, and an adjustment unit. The lower leg member is attached to the user's lower leg. The foot member is attached to the user's foot. The foot member is pivotally connected to the crus member. The elastic body has one end connected to the crus member and the other end connected to the foot member, and applies an elastic force to the foot member according to the swing angle of the foot member with respect to the crus member. The adjustment unit can change a neutral swing angle that is a swing angle when the elastic body has a natural length. Further, the adjustment unit changes the neutral swing angle when the foot member is grounded to the buckling side with respect to the neutral swing angle when the foot member is not grounded. Here, changing the neutral rocking angle to the buckling side means changing the position of the foot member at the neutral rocking angle to the buckling side. Therefore, the function of the adjustment unit described above is expressed in more detail as follows. The adjusting unit is neutral so that the position of the foot member at the neutral swing angle when the ground contact is detected is located on the bottom flexion side with respect to the position of the foot member at the neutral swing angle when the ground contact is not detected. Change the swing angle.

  According to the above lower limb orthosis, by changing the neutral swing angle to the plantar flexion side, when the lower leg of the standing leg swings forward about the ankle (that is, when the foot is dorsiflexed), the lower leg swings. The spring restoring force applied in the restraining direction (bottom bending direction) can be increased compared to before changing the neutral swing angle. In other words, the adjustment unit described above increases a force that resists swinging in the dorsiflexion direction of the foot so that the dorsiflexion of the foot accompanying the forward movement of the body does not become too fast. On the contrary, the adjustment unit adjusts the neutral swing angle so that the foot member is positioned on the dorsiflexion side when the leg is swinging compared to when the leg is standing. At the time of a free leg, compared with the neutral position at the time of standing, the force to keep the toes from falling is increased. By adjusting the neutral swing angle described above during the walking motion, the user can perform the walking motion smoothly.

  By the way, the behavior of the foot during walking is as follows. At the time of grounding, the foot is grounded from the heel, and then the entire sole is grounded. At the time of takeoff, the foot will take off from the heel and then the toes will take off. In order to accurately distinguish the free leg and the standing leg, the foot member may include a first sensor that detects ground contact of the toe portion of the foot member and a second sensor that detects ground contact of the heel portion of the foot member. In this case, the adjustment unit determines the neutral swing angle when at least one of the first sensor and the second sensor detects grounding, and when neither the first sensor nor the second sensor detects grounding. It is better to change to the buckling side than the neutral swing angle.

  According to this configuration, the toes are floating but the heel is grounded, the entire sole is grounded, the heel is floating but the toes are grounded, and the entire sole is grounded It is possible to accurately detect each state of not being performed. That is, the free leg and the standing leg can be accurately distinguished. Therefore, the neutral swing angle can be reliably set to each angle in each case of standing and swinging. Furthermore, the adjustment unit can change the neutral position according to the ground contact state.

  The neutral swing angle when the foot member is not grounded is preferably 90 degrees or less, and the neutral swing angle when the foot member is grounded is preferably larger than 90 degrees. When analyzing the behavior of a healthy person's foot, the swing angle of the foot during swinging is approximately 90 degrees or less. By setting the neutral swing angle at the swinging leg to 90 degrees or less, the swinging angle of the foot at the swinging leg is larger than 90 degrees (that is, the toe is lower than when the swinging angle is 90 degrees). Force) to force the toes upward. On the other hand, the swing angle of the foot when the free leg lands and the sole touches the ground is approximately 90 degrees or more. By setting the neutral swing angle when standing up to a value larger than 90 degrees, a force that resists swinging in the dorsiflexion direction of the foot can be applied from an early stage after the foot has landed.

  The present specification also provides a mechanism suitable for the adjustment unit described above. The adjustment unit includes a rack gear that is slidably supported by one member of the lower leg member and the foot member, a drive gear that slides the rack gear by rotating while meshing with the rack gear, and an actuator that rotates the drive gear. There may be. In that case, the rack gear may be curved along an arc centered on the swing axis of the lower leg member and the foot member. Moreover, you may make it the edge part by the side connected with said one member among the one end and the other end of an elastic body be connected with the rack gear. According to this configuration, if a pinion is used for the drive gear and the reduction ratio between the actuator and the pinion is increased, the required torque of the actuator can be reduced, and the adjustment unit can be reduced in size and weight. In addition, if a worm gear is used as the drive gear, the reverse rotation of the actuator is unlikely to occur even when a high torque reverse input is applied to the worm gear via the rack gear.

The figure which shows typically the lower limbs orthosis of 1st Example. The figure explaining the mechanism which changes a neutral rocking angle. The figure which shows operation | movement of the lower-limbs orthosis during walking movement (at the time of a free leg). The figure which shows operation | movement of the lower-limbs orthosis during walking movement (at the time of heel contact). The figure which shows operation | movement of the lower-limbs orthosis during walking movement (at the time of plantar ground contact). The figure which shows the operation | movement of the leg brace during walking movement (at the time of toe grounding). The figure which shows operation | movement of the leg brace during walking movement (at the time of takeoff). The figure which shows typically the lower limbs orthosis of 2nd Example.

The technical features of the embodiments described below are listed.
(Embodiment 1) A coil spring is used for the elastic body.
(Mode 2) A pinion or a worm gear is used as the drive gear.
(Mode 3) The foot member includes a first sensor that detects grounding of the toe portion of the foot member and a second sensor that detects grounding of the heel portion of the foot member.
The adjustment unit sets the neutral swing angle to the first angle when neither the first sensor nor the second sensor detects grounding (that is, when the foot is not grounded). The adjustment unit (1) sets the neutral swing angle to the second angle when only the second sensor detects the grounding. (2) Both the first sensor and the second sensor detect the grounding. If it is, the neutral swing angle is set to the third angle, and (3) if only the first sensor detects grounding, the neutral swing angle is set to the fourth angle. All of the second to fourth angles are on the buckling side with respect to the first angle. That is, all the neutral positions of the foot member at the second to fourth angles are located on the bottom flexion side with respect to the neutral position of the foot member at the first angle. First angle <second angle <third angle <fourth angle. That is, the foot member at the second angle is located on the buckling side with respect to the foot member at the second angle, and is located on the dorsiflexion side with respect to the foot member at the third angle and the fourth angle. The foot member at the third angle is positioned on the buckling side with respect to the foot member at the first angle and the second angle, and is positioned on the dorsiflexion side with respect to the foot member at the fourth angle. The foot member at the fourth angle is located closer to the buckling side than the foot member at any of the first angle, the second angle, and the third angle.

(First embodiment)
A lower limb orthosis 10 of the first embodiment will be described with reference to the drawings. FIG. 1 schematically shows a lower limb orthosis 10 of the first embodiment. The lower limb orthosis 10 includes a crus member 12, a foot member 14, a joint 16, an adjustment unit 20, a first sensor 44, a second sensor 46, and a controller 50 as main components.

  The lower leg member 12 is attached to the lower leg R of the user. The foot member 14 is attached to the user's foot F. The foot member 14 is swingably connected to the crus member 12 by a disc-shaped joint 16. When the user wears the lower limb orthosis 10, the joint 16 is positioned substantially coaxially with the pitch axis of the user's ankle joint. The “pitch axis” means an axis extending in the body side direction of the user. The symbol C in the figure represents the swing axis of the joint 16. When the user swings the foot in the base bending direction (arrow A direction in FIG. 1) or the dorsiflexion direction (arrow B direction in FIG. 1), the foot member 14 swings in synchronization.

  The foot member 14 includes a toe portion 40 for placing the toe of the foot F and a base portion 42 for placing a portion other than the toe of the foot F. The toe part 40 is connected to the base part 42 by a joint 48 so as to be swingable. Note that the toe portion 40 can be swung only upward from a state where it is flush with the base portion 42 (see FIG. 7), and cannot be swung downward from the state where it is flush. Although not shown in the present embodiment, the foot member 14 may be provided with a belt member for fixing the foot F.

  Both the first sensor 44 and the second sensor 46 are sensors that detect grounding. The first sensor 44 is provided on the bottom surface of the tip (toe portion) of the toe portion 40, and the second sensor is provided on the bottom surface of the rear end (heel portion) of the base portion 42. When the first sensor 44 detects grounding, it means that the toe part 40 is grounded, and when the second sensor 46 detects grounding, it means that the base part 42 is grounded. . Further, when both the first sensor 44 and the second sensor 46 detect grounding, it means that the entire sole of the foot member 14 is grounded. On the contrary, when neither the first sensor 44 nor the second sensor 46 detects the ground contact, it means that the entire sole surface of the foot member 14 is not grounded (free leg state).

  The adjustment unit 20 includes a coil spring 22, a rack gear 24, a pinion gear 26, a spur gear 28, a motor 30, and a case 32. Each of the members 24 to 30 other than the coil spring 22 is provided in a case 32 attached to the rear end portion of the joint 16. Accordingly, the case 32 and the members 24 to 30 provided in the case 32 swing around the swing axis C together with the foot member 14.

  The rack gear 24 is curved along an arc centered on the swing axis C. Gear teeth are formed outside the curved surface of the rack gear 24. The rack gear 24 is provided in the case 32 so as to be slidable along an arc centered on the swing axis C. The pinion gear 26 is a gear that meshes with the gear teeth of the rack gear 24 and rotates. The spur gear 28 is a gear attached to the motor 30 and meshes with the pinion gear 26 to rotate. When the motor 30 is driven, the spur gear 28 rotates, the spur gear 28 rotates as the spur gear 28 rotates, and the rack gear 24 slides according to the rotation direction of the pinion gear 26. That is, by driving the motor 30 in the forward and reverse directions, the position of the rack gear 24 that meshes with the pinion gear 26 is changed. Hereinafter, the position of the rack gear 24 that meshes with the pinion gear 26 may be referred to as a “mesh position”. In this embodiment, the number of teeth of the pinion gear 26 is larger than the number of teeth of the spur gear 28, and the reduction ratio of the spur gear 28 and the pinion gear 26 is larger than 1. Thereby, the rack 24 can be driven by the small motor 30. The pinion gear 26 corresponds to an embodiment of the drive gear.

  One end of the coil spring 22 is fixed to the crus member 12 by a stopper 34, and the other end is fixed to the foot member 14. More specifically, the other end of the coil spring 22 is fixed to the end of the rack gear 24. When the rack gear 24 swings as the foot member 14 swings, the length of the coil spring 22 changes, and as a result, a restoring force for restoring the natural length is generated in the coil spring 22. This restoring force (elastic force) becomes a force that urges the foot member 14 in the bottom bending direction or the dorsiflexion direction. The swing angle of the foot member 14 when the coil spring 22 has a natural length is referred to as a “neutral swing angle”. Further, the posture of the foot member 14 at the neutral swing angle (inclination around the pitch axis with respect to the crus member 12) is referred to as a “neutral position”. That is, the position of the foot member 14 when the coil spring 22 has a natural length corresponds to the neutral position. “Neutral position” and “neutral rocking angle” are equivalent, but the expression “neutral position” is easy to get familiar with to express the posture of the foot member 14. The expression “neutral position” is used. When the position of the foot member 14 is dorsiflexed from the neutral position, a moment in the bottom bending direction acts on the foot member 14 by the restoring force of the coil spring 22. When the position of the foot member 14 is bent from the neutral position, a moment in the dorsiflexion direction acts on the foot member 14 by the restoring force of the coil spring 22. This moment assists the user's walking motion.

  In this embodiment, the neutral position of the foot member 14 can be changed by driving the motor 30 and changing the meshing position of the rack gear 24. In other words, by changing the meshing position (P1 in FIG. 1, P2 in FIG. 2), the swing angle (neutral swing angle) of the foot member 14 with respect to the lower leg member 12 when the coil spring 22 has a natural length is changed. Can be changed.

  The “swing angle” in this embodiment is an angle indicated by θ in FIG. As shown in FIG. 1, the swing angle θ is perpendicular to the swing axis C and extends in parallel to the user's lower leg R, and the crus member reference line L1 is orthogonal to the swing axis C and extends in parallel to the sole. This represents the angle formed with the foot member reference line L2. The magnitude of the swing angle θ is expressed so as to increase from the crus member reference line L1 toward the foot member reference line L2. That is, when the leg member reference line L1 and the foot member reference line L2 are orthogonal to each other (see FIG. 1), 90 degrees is set, and when the leg member 14 is bent down (see FIG. 2), the leg member reference line L1 is increased from 90 degrees. .

  In FIG. 1, the meshing position of the rack gear 24 is at the position P1. In this case, the neutral swing angle of the foot member 14 is 90 degrees. The neutral swing angle in FIG. 1 is represented by the symbol θ1 (first angle θ1), and the position (neutral position) of the foot member 14 at this time is represented by the symbol 14a. Hereinafter, the neutral position (14a) of the foot member 14 at this time may be referred to as a “90-degree position”. As will be described later, in the present embodiment, the first angle θ1 (neutral position 14a) corresponds to a neutral swing angle (neutral position of the foot member 14) during swinging.

  In FIG. 2, the meshing position of the rack gear 24 is at the position P2. As can be understood from FIG. 2, the length of the coil spring 22 is equal to that in FIG. 1, but the position of the foot member 14 is bent more than in the case of FIG. 1. In other words, the neutral swing angle (the neutral position of the foot member) is changed by the adjusting unit 20. The neutral swing angle in the case of FIG. 2 is greater than 90 degrees. The neutral swing angle at this time is represented by the second angle θ2, and the neutral position of the foot member 14 at this time is represented by reference numeral 14b. At this time, the neutral position 14b of the foot member is a position on the bottom flexion side with respect to the 90-degree position (neutral position 14a). As will be described later, in the present embodiment, the second angle θ2 (neutral position 14b) corresponds to a neutral swing angle (neutral position of the foot member 14) at the time of heel contact.

  The above-described controller 50 is mounted on the crus member 12. Control lines (not shown) of the first sensor 44, the second sensor 46, and the motor 30 are connected to the controller 50. The controller 50 controls the operation of each connected device by a built-in CPU, memory, and the like (not shown). The controller 50 also includes a battery (not shown) for supplying power to the motor 30.

  The operation of each part of the lower limb orthosis 10 (processing executed by the controller 50) when the user wearing the lower limb orthosis 10 performs a walking motion will be described with reference to FIGS. 3 to 7 show an operation for one cycle from the landing of one foot to the takeoff during the walking operation. 3 to 7, only the main part of the lower limb orthosis 10 is illustrated, and some components are not illustrated. The movement from the landing to the release of the foot while walking is in the swinging leg stage (Fig. 3), the stage from the contact of the swinging leg to the entire contact of the sole (see Figure 4), There are four stages: a stage in which the body is moved forward while grounding (see FIG. 5), and a stage in which the toes are grounded and only the toes are grounded (see FIG. 6). FIG. 7 shows a stage where the toes are released and become a free leg again (same as the free leg stage). The following processing is performed by the controller 50, but since actual physical operation is realized by the adjustment unit 20, “processing performed by the controller 50” is expressed as “processing performed by the adjustment unit 20”.

(1. Swing leg stage)
As shown in FIG. 3, the adjusting unit 20 (controller 50) sets the neutral swing angle to the first swing angle during the swing leg period, that is, when neither the first sensor 44 nor the second sensor 46 detects grounding. One angle θ1 is set. As described above, at this time, the neutral position 14a of the foot is the 90 degree position (see FIG. 1). As will be described later, the neutral position 14a of the foot at this time is the neutral position of the most dorsiflexed foot. The adjusting unit 20 adjusts the neutral position so that it is positioned on the dorsiflexion side with respect to any other case, thereby making it difficult to lower the toe during swinging. The lower limb orthosis 10 functions so as to prevent the toes from coming into contact with the ground during swinging. The user can maintain the height of the toe without applying much force to the ankle as compared with the case where the lower limb orthosis 10 is not used.

(2. Landing of heels-grounding of the entire sole)
In the case of a healthy person, after the heel touches down, the foot gradually bends, and the entire sole touches down. However, when the ankle joint is inconvenient, there is a case where the plantar swing of the foot cannot be performed well. Therefore, as shown in FIG. 4, when the second sensor 46 provided in the bag detects the grounding, the adjustment unit 20 changes the neutral swing angle from the first angle θ1 to the second angle θ2. The second angle θ2 is larger than the first angle θ1. That is, the adjustment unit 20 changes the neutral swing angle to the buckling side when the saddle contact is detected. In other words, the adjusting unit 20 determines that the position of the foot member 14 at the neutral swing angle when the heel contact is detected is greater than the position of the foot member 14 at the neutral swing angle when the ground contact is not detected. Change the neutral swing angle so that it is located on the bottom bent side.

  With the above change, the user's foot gradually bends. That is, the lower limb orthosis 10 induces the plantar flexion swing of the user's foot when the heel is touched. By such processing, the user can move his / her foot smoothly from the heel contact to the entire sole contact. As described above, the change of the neutral swing angle is realized by driving the motor 30 so that the meshing position of the rack gear 24 moves from P1 to P2 (see FIGS. 1 and 2). When the entire foot of the user lands, the first sensor 44 detects ground contact.

(3. Forward movement of body)
In the case of a healthy person, the foot gradually dorsiflexes and swings as the body moves forward after the sole touches the ground. At this time, the healthy person adjusts the force applied to the ankle so that the body does not wobble or the forward moving speed of the body does not become excessive. However, if the ankle joint is disabled, such adjustment may not be performed properly. Therefore, as shown in FIG. 5, in the stage where the body is moved forward after the entire surface of the sole is grounded, the lower limb orthosis 10 prevents the dorsiflexion swing of the foot accompanying the forward movement of the body from becoming too fast. Suppresses rocking. As shown in FIG. 5, when both the first sensor 44 and the second sensor 46 detect grounding, the adjustment unit 20 drives the motor 30 to change the neutral swing angle from the second angle θ2 to the third angle. Change to θ3. In other words, the adjustment unit 20 moves the neutral position of the foot member 14 from the neutral position 14b to the neutral position 14c. The third angle θ3 (neutral position 14c) is located closer to the buckling side than the second angle θ2 (neutral position 14b). The adjustment unit 20 changes the neutral swing angle by changing the meshing position of the rack gear 24, but the actual foot member 14 does not move from the position 14b to 14c. It should be noted that a neutral position 14c indicated by a two-dot chain line in FIG. 5 indicates a virtual foot member position.

  Since the neutral swing angle (neutral position) moves further to the bottom flexion side, the moment that the lower limb orthosis 10 urges the foot member 14 in the direction of bottom flexion swing in the state of FIG. 5 increases. That is, the lower limb orthosis 10 applies a large resistance force to the user's foot in the direction of swinging the lower leg backward. This resistance force (moment) suppresses the forward rocking speed of the lower leg. As a result, the fluctuation of the body is suppressed. When the user moves the body forward (see arrow D in FIG. 5) and then the heel is taken off, the second sensor 46 is in a non-detection state.

(4. Take off from the pass)
For a healthy person, move the body forward, lift the heel, kick the ground with the toes, and leave. When kicking the ground with your toes, your feet will bend further. However, it may be difficult for a person with an ankle joint disability to sufficiently buckle the foot. Therefore, as shown in FIG. 6, the lower limb orthosis 10 has a neutral swing angle so that the urging force toward the bottom bending direction is increased so that the foot can be bent to the maximum with the separation of the heel. change. As shown in FIG. 6, when the heel is released at the end of the stance, the second sensor 46 is in a non-detection state, and only the first sensor 44 of the toe portion 40 is in a state of detecting grounding. When the second sensor 46 of the heel does not detect grounding and the first sensor 44 of the toe detects grounding, the adjusting unit 20 drives the motor 30 to change the neutral swing angle from the third angle θ3. Change to the fourth angle θ4. The fourth angle θ4 is located further on the bottom buckling side than the third angle θ3. In other words, the adjusting unit 20 is such that the position (14d) of the foot member 14 when the neutral swing angle is the fourth angle θ4 is closer to the buckling side than the position of the foot member 14 when the third angle θ3. The neutral swing angle θ4 is changed to the fourth angle so as to be positioned. In other words, the adjustment unit 20 changes the neutral swing angle from the third angle θ3 to the fourth angle θ4, and shifts the neutral position of the foot member 14 to the buckling side.

  By changing the neutral swing angle from the third angle θ3 to the fourth angle θ4, the neutral position of the foot member 14 is further at the position 14d on the bottom side (this position may be referred to as the “maximum bottom position”). It becomes. As a result, the foot is biased in a direction that further causes the foot to bend. The biasing force at this time assists the user in kicking the toe. The symbol θa in FIG. 6 shows an example of the swing angle at the time of toe grounding. At this time, the auxiliary force that the lower limb orthosis 10 applies to the user is given by K (θ4-θa) (K is a spring constant). The fourth angle θ4 is larger than the third angle θ3. It can be understood from this formula that the force with which the lower limb orthosis 10 assists the user is increased by changing the neutral swing angle. When the user subsequently removes the toe, the first sensor 44 is also in a non-detection state.

(5. Toe off-swinging leg state)
When it becomes a free leg again (that is, when neither the first sensor 44 nor the second sensor 46 detects grounding), the adjusting unit 20 drives the motor 30 to set the neutral swing angle to the fourth angle. The angle is changed from θ4 to the first angle θ1 (FIG. 7). Reference sign θb in FIG. 7 shows an example of a swing angle at the time of a free leg. At this time, the auxiliary force that the lower limb orthosis 10 applies to the user is given by K (θb−θ1) (K is a spring constant). The first angle θ1 is smaller than the fourth angle θ4. Also from this formula, it is understood that the lower limb orthosis 10 effectively assists the toes not to fall by changing the neutral swing angle to the first angle θ1 during the swinging leg. When the user subsequently removes the toe, the first sensor 44 is also in a non-detection state.

  The lower limb orthosis 10 of the present embodiment is neutrally swayed so that the foot member 14 is located on the plantar flexion side when standing (see FIGS. 4 to 6) compared to the swinging leg (see FIGS. 3 and 7). Adjust the moving angle. By shifting the neutral position to the bottom bent side, the spring restoring force applied in the bottom bent direction at the time of ground contact can be increased compared to before shifting. That is, the force against the swinging of the foot in the dorsiflexion direction increases so that the dorsiflexion of the foot accompanying the forward movement of the body does not become too fast. On the other hand, the neutral swing angle is adjusted so that the foot member 14 is positioned on the dorsiflexion side during the swinging leg compared to the standing leg. At the time of a free leg, compared with the neutral position at the time of standing, the force to keep the toes from falling is increased.

  In the lower limb orthosis 10 of this embodiment, the foot member 14 during the walking motion is in the heel-contacting state, the sole-grounding state, the heel-off state, or the free-leg state from the detection state of the first sensor 44 and the second sensor 46. The neutral swing angle is changed according to the state of the foot member 14. By appropriately changing the neutral position of the foot member 14 according to the state of the foot member 14 during the walking motion, the user's walking motion can be effectively assisted.

  In this embodiment, the number of teeth of the pinion gear 26 is larger than the number of teeth of the spur gear 28, and the reduction ratio of the spur gear 28 and the pinion gear 26 is larger than 1. Thereby, the required torque of the motor 30 can be made small. The entire adjustment unit 20 can be reduced in size and weight.

(Second embodiment)
A second embodiment will be described with reference to the drawings. As shown in FIG. 8, the lower limb orthosis 110 of the second embodiment is different from the first embodiment using the pinion gear 26 and the spur gear 28 in that the adjustment unit 20 uses a worm gear 126. Other points are the same as in the first embodiment. As shown in FIG. 8, the adjustment unit 120 in this embodiment includes a coil spring 122, a rack gear 124, and a case 132 similar to those in the first embodiment. In this embodiment, when the worm gear 126 attached to the motor 130 is rotated, the meshing position of the helical thread provided on the worm gear 126 and the gear teeth of the rack gear 124 changes. Note that the worm gear 126 of the present example is also an example of an embodiment of the drive gear.

  In the second embodiment, a worm gear 126 is used as a mechanism for sliding the rack gear 124. Therefore, even when reverse input of high torque is applied to the worm gear 126 via the rack gear 124, the reverse rotation of the motor 130 is unlikely to occur.

Modifications of the above embodiments are listed below.
(1) The neutral swing angle set in each state of the heel contact state, the sole contact state, the heel-off state, and the free leg state is not limited to those described in the above embodiments. The neutral swing angle (first angle) of the free leg state, the neutral swing angle (second angle) of the heel-contacted state, the neutral swing angle (third angle) of the sole-grounded state, and the heel-off state If the neutral swing angle is set to increase in the order of the neutral swing angle (fourth angle), specific numerical values can be arbitrarily determined for each user. Therefore, for example, the neutral swing angle (first angle) of the free leg state is not limited to 90 degrees as described above. Preferably, the first angle is smaller than 90 degrees. Further, the second to fourth angles are not limited to the angles of the above embodiment. Preferably, the second to fourth angles are all greater than 90 degrees, and the second angle <the third angle <the fourth angle may be satisfied.
(2) In each of the above-described embodiments, the state of the foot member 14 during the walking motion is divided into four states, ie, a heel-contacting state, a sole-grounding state, a heel-off state, and a free leg state. The neutral rocking angle is set so that the foot member 14 is positioned at a predetermined neutral position depending on whether or not it is in a state. However, the state of the foot member 14 during the walking motion may be further divided and determined, and the neutral swing angle may be continuously changed according to the state of the foot member 14.
(3) In each of the above-described embodiments, the coil springs 22 and 122 are used as elastic bodies for applying a restoring force to the foot member 14. However, a damper may be used as the elastic body instead of the coil springs 22 and 122. Moreover, you may use combining a coil spring and a damper.

  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.

10: Lower limb orthosis, 12: Lower leg member, 14: Foot member, 16: Joint, 20: Adjustment part, 22: Coil spring, 24: Rack gear, 26: Pinion gear, 28: Spur gear, 30: Motor, 32: Case, 34 : Stopper, 40: Toe part, 42: Base part, 44: First sensor, 46: Second sensor, 48: Joint, 50: Controller, C: Oscillating shaft, F: Foot, R: Lower leg, P1: Engagement position

Claims (4)

A lower leg member to be worn on the user's lower leg;
A foot member that is swingably coupled to the lower leg member and is attached to a user's foot;
An elastic body having one end connected to the crus member and the other end connected to the foot member, and applying an elastic force to the foot member according to a swing angle of the foot member with respect to the crus member;
An adjustment unit capable of changing a neutral rocking angle that is the rocking angle when the elastic body has a natural length, and
The lower limb orthosis characterized in that the adjustment unit changes the neutral swing angle when the foot member is grounded to the buckling side rather than the neutral swing angle when the foot member is not grounded. The foot member includes a first sensor that detects grounding of a toe portion of the foot member, and a second sensor that detects grounding of a heel portion of the foot member,
The adjustment unit detects a neutral swing angle when at least one of the first sensor and the second sensor detects grounding, and both the first sensor and the second sensor detect grounding. The lower limb orthosis according to claim 1, wherein the lower limb orthosis is changed to the plantar flexion side with respect to the neutral swing angle when there is no.   The swing angle is expressed as an angle from a crus member reference line that extends perpendicular to the swing axis of the lower leg member and the foot member and extends parallel to the lower leg to a foot member reference line that extends perpendicular to the swing axis and parallel to the sole. The neutral swing angle when the foot member is not grounded is 90 degrees or less, and the neutral swing angle when the foot member is grounded is greater than 90 degrees. Or the lower limb orthosis of 2. The adjustment unit is
A rack gear slidably supported on one member of the lower leg member and the foot member;
A drive gear that slides the rack gear by rotating while meshing with the rack gear;
An actuator for rotating the drive gear;
The rack gear is curved along an arc centered on a swing axis of the crus member and the foot member,
4. The end portion of the elastic body on the side connected to the one member of the one end and the other end is connected to the rack gear. 5. Lower limb orthosis.

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