Assistive force generating mechanism for generating an assistive force of an assistive device, and assistive device

Abstract

To meet a request to change assistance force of assistance equipment according to intended use.SOLUTION: An assistance force generation mechanism 100 includes: a first energizing part 104 and a second energizing part 108 disposed side by side with each other; a slider 110 provided movably between the first energizing part 104 and the second energizing part 108; and a lock part 112 movable between an engagement position to engage with the slider 110 to prohibit movement of the slider 110 and a non-engagement position to release the engagement and permit the movement of the slider. The assistance force generation mechanism 100 generates assistance force by the action of the first energizing part 104 when the lock part 112 is disposed at the engagement position, and generates assistance force by the action of the first energizing part 104 and the second energizing part 108 when the lock part 112 is disposed at the non-engagement position.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to an assistive force generating mechanism that generates an assistive force for an assistive device that assists bending and stretching movements of the body, and the assistive device itself. [Background technology]

[0002] BACKGROUND ART Assistive devices that assist bending and stretching movements of the human body are known (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-120936 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for the assistive force of an assistive device to be able to be changed depending on the application. [Means for solving the problem]

[0005] In one aspect of the present disclosure, an assistive force generation mechanism for generating an assistive force of an assistive orthosis that assists in bending and stretching movements of the body includes a first biasing portion and a second biasing portion arranged side by side, a slider movably provided between the first biasing portion and the second biasing portion, and a locking portion that engages with the slider and is movable between an engaged position that prohibits movement of the slider relative to the second biasing portion and a disengaged position that disengages and allows movement of the slider. The assistive force generation mechanism is configured to generate an assistive force by the action of the first biasing portion when the locking portion is arranged in the engaged position, and to generate an assistive force by the action of the first biasing portion and the second biasing portion when the locking portion is arranged in the disengaged position. [Brief explanation of the drawings]

[0006] [Figure 1]FIG. 1 is a diagram showing an assistive device according to one embodiment, showing the body in an upright position. [Figure 2] 2 shows the lower arm shown in FIG. 1. [Figure 3] 2 shows the upper arm shown in FIG. 1. [Figure 4] The link portion shown in Figure 1 is shown. [Figure 5] FIG. 2 is an enlarged view of the assist force generation mechanism shown in FIG. [Figure 6] 6 is a perspective view of the assist force generation mechanism shown in FIG. 5, showing a state in which a locking portion is placed in a non-engaged position. FIG. [Figure 7] FIG. 7 is a cross-sectional view of the assist force generation mechanism shown in FIG. 6. [Figure 8] 6 is a perspective view of the assist force generation mechanism shown in FIG. 5, showing a state in which a locking portion is placed at an engagement position. FIG. [Figure 9] FIG. 9 is a cross-sectional view of the assist force generation mechanism shown in FIG. 8. [Figure 10] 6 shows the power section of the actuator shown in FIG. 5. [Figure 11] This shows a state in which the power unit shown in FIG. 10 has rotated the rotating unit. [Figure 12] This shows the assistive device when the body is in a crouching position. [Figure 13] 10 shows a state in which the assist force generating mechanism generates an assist force when the locking portion is disposed in the engagement position. [Figure 14] 10 shows a state in which the assist force generating mechanism generates an assist force when the locking portion is disposed in the disengaged position. [Figure 15] 10 shows a mechanism of an assistive device according to another embodiment. [Figure 16] FIG. 16 shows a block diagram of the auxiliary orthosis shown in FIG. [Figure 17] This shows a state in which a person wearing the assistive device shown in Figure 15 on his legs is walking down a slope. [Figure 18] This shows a state in which a person wearing the assistive device shown in Figure 15 on his legs is crossing a slope. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the various embodiments described below, like elements will be designated by like reference numerals, and redundant description will be omitted. In the following description, directions will be referenced to an orthogonal coordinate system C in the drawings, and for convenience, the positive direction of the x-axis of the coordinate system C will be referred to as forward, the positive direction of the y-axis of the coordinate system C will be referred to as leftward, and the positive direction of the z-axis will be referred to as upward.

[0008] First, an assistive orthosis 10 according to one embodiment will be described with reference to Fig. 1. The assistive orthosis 10 is intended to assist in the bending and stretching movements of the thighs B1 and shins B2 (i.e., knee bending and stretching movements) of a body B. The thighs B1 and shins B2 are connected via a knee joint B3, and the body B performs knee bending and stretching movements by bending and stretching the thighs B1 and shins B2 at the knee joint B3.

[0009] The assistive orthosis 10 comprises a mechanism 12 and attachment bands 14 and 16. Each of the attachment bands 14 and 16 is made of, for example, natural or synthetic fiber cloth, rubber, resin, or a combination of these, and has high flexibility and stretchability so as to fit the body B. In this embodiment, the attachment band 14 is attached by wrapping it around the shin B2, while the attachment band 16 is attached by wrapping it around the thigh B1.

[0010] The mechanical unit 12 is disposed between the attachment bands 14 and 16. The mechanical unit 12 will be described below with reference to Figs. 1 to 5. The mechanical unit 12 has arms 18 and 20, a link unit 22, and an assist force generating mechanism 100. The arm 18 is attached to the attachment band 14, and is attached to the shin B2 via the attachment band 14.

[0011] 2, the arm 18 is a flat, unitary member made of a metal such as aluminum, and includes a main body 26, a gear portion 28, and an extension portion 30. The main body 26 has an upper end 32 and a lower end 34 opposite the upper end 32, and extends from the upper end 32 to the lower end 34 along an axis A1.

[0012] More specifically, the main body 26 has a rectangular first portion 36 extending straight along the axis A1 and a generally sector-shaped second portion 38 extending upward from the upper end of the first portion 36. The first portion 36 defines a lower end 34, while the second portion 38 defines an upper end 32. The first portion 36 is attached to the mounting band 14 (FIG. 1). The second portion 38 widens as it extends upward from the upper end of the first portion 36.

[0013] A shaft 40 is provided at the upper end portion 32. The shaft 40 is, for example, cylindrical and is formed integrally with the upper end portion 32 so as to extend rightward from the upper end portion 32. The upper end portion 32 also has an arc-shaped outer peripheral surface 42. The outer peripheral surface 42 is disposed approximately coaxially with the shaft 40.

[0014] The gear portion 28 has a predetermined diameter R1 (e.g., a pitch diameter) and is formed integrally with the upper end portion 32. More specifically, the gear portion 28 has a plurality of teeth 28a aligned in the circumferential direction of an outer circumferential surface 42 of the upper end portion 32. Each tooth 28a is formed integrally with the outer circumferential surface 42 so as to protrude radially outward from the outer circumferential surface 42.

[0015] The extension portion 30 is formed integrally with the upper end portion 32 of the main body portion 26 so as to extend outward from the upper end portion 32. More specifically, the extension portion 30 is disposed adjacent to the front side of the gear portion 28 at the upper end portion 32 and extends straight from the upper end portion 32 along an axis A2. The axis A2 is inclined at an angle θ1 with respect to the axis A1 of the main body portion 26. In this embodiment, the angle θ1 is an acute angle (for example, θ1 = 10° to 60°).

[0016] 3, arm 20 is a flat, unitary member made of a metal such as aluminum, and has a main body 44 and a gear part 46. Main body 44 has an upper end 48 and a lower end 50 opposite to upper end 48, and extends straight from upper end 48 to lower end 50 along axis A3.

[0017] A shaft 52 is provided at the lower end portion 50. The shaft 52 is, for example, cylindrical and is integrally formed with the lower end portion 50 so as to extend rightward from the lower end portion 50. Further, the lower end portion 50 has an arcuate outer peripheral surface 54. The outer peripheral surface 54 is disposed substantially coaxially with the shaft 52.

[0018] The gear portion 46 has a predetermined diameter R2 (for example, pitch diameter) and is integrally formed with the lower end portion 50. More specifically, the gear portion 46 has a plurality of tooth portions 46a aligned in the circumferential direction of the outer peripheral surface 54 of the lower end portion 50. Each tooth portion 46a is integrally formed with the outer peripheral surface 54 so as to project radially outward from the outer peripheral surface 54.

[0019] The tooth portion 46a engages with the tooth portion 28a (FIG. 2) of the gear portion 28. In the present embodiment, the diameter R2 of the gear portion 46 is different from the diameter R1 of the gear portion 28. More specifically, the diameter R2 of the gear portion 46 is smaller than the diameter R1 of the gear portion 28 (R2 < R1), and the ratio of the diameter R2 to the diameter R1 is set, for example, at R2:R1 = 12:17.

[0020] Referring to FIG. 4, the link portion 22 is an integrally formed flat plate member made of a metal such as aluminum and has a main body portion 56 and a lever portion 58. The main body portion 56 extends straight along the axis A4, and its lower end portion 56a is rotatably connected to the arm 18, and its upper end portion 56b is rotatably connected to the arm 20. More specifically, a through hole 60 is formed in the lower end portion 56a of the main body portion 56, while a through hole 62 is formed in the upper end portion 56b of the main body portion 56.

[0021] The shaft 40 (FIGS. 1 and 2) of the arm 18 is rotatably inserted into the through hole 60 of the main body portion 56, and a fastening tool (not shown) such as a bolt is fastened to the shaft 40. Thereby, the upper end portion 32 of the arm 18 is connected to the lower end portion 56a of the main body portion 56 so as to be relatively rotatable about the central axis of the shaft 40.

[0022] Meanwhile, the shaft 52 (FIGS. 1 and 3) of the arm 20 is rotatably inserted into the through-hole 62 of the main body 56, and a fastener (not shown) such as a bolt is fastened to the shaft 52. As a result, the lower end 50 of the arm 20 is connected to the upper end 56b of the main body 56 so as to be relatively rotatable about the central axis of the shaft 52.

[0023] The lever portion 58 is formed integrally with the lower end portion 56a of the main body portion 56 so as to extend from the lower end portion 56a along the axis A5. The axis A5 is inclined at an angle θ2 with respect to the axis A4. In this embodiment, the angle θ2 is an acute angle (for example, θ2 = 30° to 80°).

[0024] Lever portion 58 has a curved side surface 58a. Side surface 58a extends in a curved manner so as to bulge outward from its base end toward its tip. Side surface 58a may be an arcuate surface having a predetermined radius of curvature, or may be a combination of multiple arcuate surfaces each having multiple radii of curvature.

[0025] The assistive force generation mechanism 100 generates an assistive force Fa for the assistive orthosis 10. In this embodiment, the assistive force generation mechanism 100 is provided on the extension part 30 of the arm 18, as shown in FIG. 1. The assistive force generation mechanism 100 will be described below with reference to FIGS. 5 to 7. The assistive force generation mechanism 100 includes a fixed shaft 102, a first biasing part 104, a housing 106, a second biasing part 108 (FIG. 7), a slider 110, a locking part 112, and an actuator 114.

[0026] The fixed shaft 102 has a shaft portion 102a that extends straight along an axis A6, and a flange portion 102b that protrudes outward from the upper end of the shaft portion 102a and is fixed to the extension portion 30 of the arm 18. The axis A6 may be arranged to be parallel to the axis A2 of the extension portion 30 (FIGS. 1 and 2).

[0027] The first biasing portion 104 is inserted between the slider 110 and the flange portion 102b. In the present embodiment, the first biasing portion 104 is a compression coil spring having a first spring constant k1, and expands and contracts in the direction of the axis A6. The first biasing portion 104 is positioned so as to extend in the direction of the axis A6 by inserting the shaft portion 102a therethrough. When the first biasing portion 104 is compressed by a displacement amount x in the direction of the axis A6, a biasing force F1 (= k1·x) is generated as its reaction force.

[0028] The housing 106 is hollow and receives a part of the shaft portion 102a and the slider 110. Specifically, the housing 106 has a substantially rectangular bottom portion 106a, a cylindrical side wall portion 106b extending from the bottom portion 106a, and a flange portion 106c extending outward from the upper end of the side wall portion 106b. The side wall portion 106b has a rectangular outer shape and, together with the bottom portion 106a, defines a quadrangular prism-shaped internal space S.

[0029] As shown in FIG. 7, the second biasing portion 108 is housed in the internal space S of the housing 106 and is inserted between the slider 110 and the bottom portion 106a. In the present embodiment, the second biasing portion 108 is a compression coil spring having a second spring constant k2 (≠ k1) different from the above-described first spring constant k1, and expands and contracts in the direction of the axis A6. The second biasing portion 108 is positioned so as to extend in the direction of the axis A6 by inserting the shaft portion 102a therethrough. Thus, the first biasing portion 104 and the second biasing portion 108 are arranged so as to be aligned with each other in the direction of the axis A6.

[0030] When the second biasing portion 108 is compressed by a displacement amount x in the direction of the axis A6, a biasing force F2 (= k2·x) is generated as its reaction force. Here, in the present embodiment, the second spring constant k2 is smaller than the above-described first spring constant k1 (k2 < k1). Therefore, when the first biasing portion 104 and the second biasing portion 108 are compressed by a displacement amount x in the direction of the axis A6, biasing forces F1 and F2 having different magnitudes are generated respectively (specifically, F1 > F2).

[0031] The slider 110 is provided between the first biasing portion 104 and the second biasing portion 108 so as to be movable along the axis A6. Specifically, the slider 110 has a slider body 110a and a plurality of claw portions 110b. The slider body 110a has a substantially rectangular outer shape, and a through-hole 110c (FIG. 7) is formed in the center thereof, penetrating the slider body 110a in the direction of the axis A6.

[0032] A portion of the slider body 110a is received in the internal space S of the housing 106 so as to be movable in the direction of the axis A6. In this embodiment, the slider body 110a and the internal space S (i.e., the inner surface of the side wall portion 106b) have corresponding rectangular outer shapes. With this configuration, the slider body 110a is restricted from rotating about the axis A6 relative to the housing 106, while its movement in the direction of the axis A6 is guided by the side wall portion 106b.

[0033] The shaft portion 102a is inserted into the through-hole 110c so as to be relatively slidable, thereby allowing the slider 110 to slide on the shaft portion 102a in the direction of the axis A6. In addition, a ring-shaped flange portion 110d (FIG. 6) protruding outward from the upper end portion is integrally formed on the upper end portion of the slider body 110a.

[0034] The first biasing portion 104 has an upper end that abuts against the flange portion 102b of the fixed shaft 102, and a lower end that abuts against the flange portion 110d of the slider 110. The second biasing portion 108 has an upper end that abuts against the lower end surface of the slider main body 110a, and a lower end that abuts against the bottom portion 106a of the housing 106.

[0035] Each of the claws 110b is integrally formed with the flange 110d of the slider body 110a so as to protrude outward from the flange 110d. In this embodiment, a total of four claws 110b are arranged at approximately equal intervals around the circumferential direction of the flange 110d.

[0036] The locking portion 112 is disposed adjacent to the upper side of the flange portion 106c of the housing 106 so as to be rotatable about the axis A6. Specifically, the locking portion 112 has a ring portion 112a, a plurality of grooves 112b, and an engaging portion 112c. The ring portion 112a is a substantially cylindrical member and is provided so as to be rotatable about the axis A6 so as to surround the slider main body 110a.

[0037] Each of the grooves 112b is formed in the ring portion 112a so as to extend parallel to the direction of the axis A6 (i.e., the moving direction of the slider 110). In this embodiment, a total of four grooves 112b are arranged at approximately equal intervals in the circumferential direction of the ring portion 112a so as to correspond to the positions of the claws 110b of the slider 110. Each of the grooves 112b opens upward at the upper end of the ring portion 112a so as to be able to receive the corresponding claw 110b therein. The engagement portion 112c has a substantially U-shaped outer shape when viewed from above, and is formed integrally with the ring portion 112a so as to protrude outward from the lower end of the ring portion 112a.

[0038] The locking portion 112 (i.e., the ring portion 112a) rotates around the axis A6 between an engagement position P1 and a disengagement position P2. Figures 6 and 7 show the locking portion 112 in the disengagement position P2. When the locking portion 112 is in the disengagement position P2, the groove 112b of the locking portion 112 and the corresponding claw portion 110b are aligned in the direction of the axis A6.

[0039] 8 and 9 show the state in which the locking portion 112 is disposed in the engagement position P1. When disposed in the non-engagement position P2, the grooves 112b of the locking portion 112 are shifted in the circumferential direction from the corresponding claws 110b. As a result, each claw 110b faces the upper end surface of the ring portion 112a.

[0040] The actuator 114 drives the locking portion 112 between an engaged position P1 and a disengaged position P2. Specifically, the actuator 114 has an actuator housing 116, a rotating portion 118, and a power portion 120 (FIG. 10). The actuator housing 116 is hollow and is fixed to the housing 106 via a mounting fixture 122. The actuator housing 116 accommodates the power portion 120, which will be described later, inside it.

[0041] The rotating part 118 is a rod-shaped member that extends linearly, and is provided in the actuator housing 116 so as to be rotatable about an axis A7 that is perpendicular to the axis A6. The upper end of the rotating part 118 is inserted into the engaging part 112c of the locking part 112, thereby engaging with the engaging part 112c.

[0042] The power unit 120 rotates the rotating unit 118, thereby rotating the lock unit 112 between an engaged position P1 and a disengaged position P2 via the rotating unit 118. More specifically, as shown in Fig. 10, the power unit 120 has a lever unit 124, a base unit 126, a spring 128, and a pair of shape memory alloys (SMAs) 130a and 130b.

[0043] Lever portion 124 is fixed integrally to pivot portion 118 and pivots about axis A7 together with pivot portion 118. Base portion 126 is disposed opposite lever portion 124 so as to move toward and away from lever portion 124. Spring 128 is interposed between lever portion 124 (or pivot portion 118) and base portion 126 and biases lever portion 124 and base portion 126 so as to maintain a constant distance between lever portion 124 and base portion 126.

[0044] The pair of SMAs 130a and 130b are stretched between the lever portion 124 and the base portion 126. The upper ends of the SMAs 130a and 130b are connected to the rotating portion 118 via the lever portion 124. When an electric current is applied to each of the SMAs 130a and 130b, the SMAs 130a and 130b contract in the longitudinal direction, and when the electric current is stopped, the SMAs 130a and 130b extend to their original length.

[0045] Power unit 120 utilizes the elasticity of SMAs 130a and 130b to generate power that rotates rotating unit 118. For example, from the state shown in Fig. 10, an electric current is applied to the right SMA 130b of the pair of SMAs 130a and 130b. This causes SMA 130b to contract, and applies torque to rotating unit 118 via lever unit 124 in the clockwise direction as viewed from the front side of the paper in Fig. 10.

[0046] As a result, the rotating part 118 rotates about the axis A7 by a predetermined angle θ3 (for example, θ3 ≈ 30°) from the initial position P3 shown in Fig. 10, and is disposed at the rotation position P4 shown in Fig. 11. At this time, tension is applied to the left SMA 130a, and the SMA 130a is pulled in its length direction and slightly stretched.

[0047] On the other hand, when the current to SMA 130b is stopped, SMA 130b gradually expands in its longitudinal direction, while SMA 130a is released from the tension and contracts due to its restoring force. As a result, rotating portion 118 rotates counterclockwise around axis A7 and returns from rotation position P4 shown in FIG. 11 to initial position P3 shown in FIG. 10. Spring 128 maintains the distance between lever portion 124 and base portion 126, thereby preventing overload from being applied to SMAs 130a and 130b, which expand and contract in this manner. This prevents damage to SMAs 130a and 130b.

[0048] As the rotating part 118 rotates between the initial position P3 and the rotation position P4 due to the action of the power part 120, the locking part 112 rotates between the engagement position P1 (FIG. 6) and the disengagement position P2 (FIG. 8). Note that in FIGS. 10 and 11, the rotating part 118 is shown by dotted lines for ease of understanding.

[0049] Next, the function of the assistive orthosis 10 will be described. Fig. 1 shows an upright posture in which the thigh B1 and shin B2 are extended and upright. In this upright posture, the arms 18 and 20 are placed in the extended position shown in Fig. 1. When placed in the extended position, the axis A1 of the arm 18, the axis A3 of the arm 20, and the axis A4 of the main body 56 of the link portion 22 are approximately parallel to one another.

[0050] Furthermore, the lever portion 58 is disposed at a first relative position RP1 with respect to the arm 18. At this time, the first biasing portion 104 and the second biasing portion 108 of the assistive force generation mechanism 100 are maintained in an extended state, and the assistive force generation mechanism 100 does not generate the assistive force Fa. In the upright posture shown in FIG. 1, the body B faces forward.

[0051] On the other hand, Figure 12 shows a crouching posture in which the thigh B1 and shin B2 are bent at the knee joint B3. Note that in Figure 12, the attachment bands 14 and 16 are shown with dotted lines for ease of understanding. In the crouching posture shown in Figure 12, the arms 18 and 20 are positioned in a bent position. When positioned in the bent position, the axis A1 of the arm 18, the axis A3 of the arm 20, and the axis A4 of the main body 56 of the link portion 22 are non-parallel to each other, and the axes A1 and A3 form an acute angle. Furthermore, the lever portion 58 is positioned at a second relative position RP2 with respect to the arm 18.

[0052] 1 to the crouching position shown in Fig. 12, the arm 20 rotates relative to the link portion 22 about the central axis of the shaft 52 in a counterclockwise direction as viewed from the right side, while the arm 18 rotates relative to the link portion 22 about the central axis of the shaft 40 in a clockwise direction as viewed from the right side. As a result, the arms 18 and 20 bend from an extended position to a bent position.

[0053] This bending movement of the arms 18 and 20 is guided by the engagement between the gear portion 28 of the arm 18 and the gear portion 46 of the arm 20, and by the link portion 22 that connects the arms 18 and 20 so that they can rotate relative to one another. As a result, during the bending movement of the arms 18 and 20, the lower end portion 50 of the arm 20 is guided so as to revolve around the shaft 40 disposed in the arm 18 in a counterclockwise direction when viewed from the right side.

[0054] On the other hand, as the arms 18 and 20 bend from the extended position to the bent position, the lever portion 58 rotates relative to the arm 18 from a first relative position RP1 to a second relative position RP2 around the central axis of the shaft 40 in the counterclockwise direction as viewed from the right side. As the lever portion 58 rotates relative to the arm 18 in this manner, the side surface 58a of the lever portion 58 slides on the bottom portion 106a of the housing 106 of the assistive force generation mechanism 100, and pushes the bottom portion 106a in the first direction D1 of the axis A6 (i.e., the axis A2).

[0055] As a result, the housing 106 of the assistive force generation mechanism 100 is displaced in the first direction D1. Assume that the locking portion 112 (ring portion 112a) is located at the engagement position P1 (FIGS. 8 and 9) at this time. In this case, the housing 106 is pushed in the first direction D1 by the lever portion 58, and is displaced in the first direction D1 together with the locking portion 112.

[0056] However, the upper end surface of the ring portion 112a, which is positioned at the engagement position P1, engages with the claw portion 110b of the slider 110, thereby prohibiting relative movement of the slider 110 with respect to the housing 106, the second biasing portion 108, and the locking portion 112. Therefore, in this case, the second biasing portion 108 is not substantially compressed in the first direction D1.

[0057] In this state, when the housing 106 is further pushed in the first direction D1 by the lever portion 58, the housing 106, the second biasing portion 108, the locking portion 112, and the slider 110 are displaced together in the first direction D1, compressing the first biasing portion 104 in the first direction D1, as shown in FIG. 13.

[0058] As a reaction force, the first biasing portion 104 applies a biasing force F1 acting in a second direction D2 opposite to the first direction D1 to the lever portion 58 via the slider 110, the locking portion 112, and the housing 106. The biasing force F1 thus applied to the lever portion 58 by the action of the first biasing portion 104 becomes an assisting force Fa1 of the assist orthosis 10 that assists the flexion and extension movement of the thigh B1 and the shin B2. In other words, when the locking portion 112 is disposed in the engagement position P1, the assisting force Fa1 becomes the biasing force F1 generated by the action of the first biasing portion 104.

[0059] Meanwhile, suppose that the locking portion 112 (ring portion 112a) is disposed at the disengagement position P2 (FIGS. 6 and 7). In this case, the housing 106, which is pushed in the first direction D1 by the lever portion 58, is displaced in the first direction D1 together with the locking portion 112. At this time, because the locking portion 112 is disposed at the disengagement position P2, the claw portion 110b of the slider 110 relatively enters the groove portion 112b formed in the locking portion 112, which moves in the first direction D1 together with the housing 106.

[0060] This allows the slider 110 to move relative to the housing 106, the second biasing portion 108, and the locking portion 112. As a result, the housing 106 and the locking portion 112 move relative to the slider 110 in the first direction D1, and this causes the second biasing portion 108 (FIG. 14) interposed between the slider 110 and the bottom portion 106a inside the housing 106 to be compressed in the first direction D1.

[0061] In this state, when the housing 106 is further pushed in the first direction D1 by the lever portion 58, the second biasing portion 108 is further compressed, and the housing 106, the slider 110, and the locking portion 112 are displaced in the first direction D1. As a result, as shown in FIG. 14 , the first biasing portion 104 is also compressed in the first direction D1.

[0062] Thus, when the first biasing portion 104 is compressed, the first biasing portion 104 applies a biasing force F1 acting in the second direction D2 to the lever portion 58 via the slider 110, the second biasing portion 108, and the housing 106, according to its displacement amount x. Also, the second biasing portion 108 applies a biasing force F2 acting in the second direction D2 to the lever portion 58 via the housing 106, according to its displacement amount x.

[0063] The biasing force F12 applied to the lever portion 58 by the actions of the first biasing portion 104 and the second biasing portion 108 is equivalent to the biasing force generated by the action of the combined spring SR of the first biasing portion 104 and the second biasing portion 108 connected in series to each other, and is the assisting force Fa of the assist device 10 that assists the flexion and extension movements of the thigh portion B1 and the shin portion B2. 12 That is, when the locking portion 112 is disposed at the non-engagement position P2, the assisting force Fa 12 becomes the biasing force F12 generated by the actions of the first biasing portion 104 and the second biasing portion 108 (i.e., the combined spring RS).

[0064] Since the spring constant k12 of this combined spring SR is k12 = k1·k2 / (k1 + k2) < k1, the assisting force Fa generated by the combined spring SR 12 can be smaller than the above-described assisting force Fa1 (Fa 12 > Fa1). Thus, in the present embodiment, the actuator 114 selectively disposes the locking portion 112 at the engagement position P1 or the non-engagement position P2, so that the assisting force Fa generated as the assisting force generation mechanism 100 can be switched between the assisting force Fa1 and the assisting force Fa 12 and.

[0065] Conversely, when the body B transitions from the squatting posture shown in FIG. 12 to the upright posture shown in FIG. 1, the arm 20 relatively rotates clockwise around the central axis of the shaft 52 with respect to the link portion 22, while the arm 18 relatively rotates counterclockwise around the central axis of the shaft 40 with respect to the link portion 22, as viewed from the right side. As a result, the arms 18 and 20 extend from the bent position to the extended position.

[0066] This extension movement of arms 18 and 20 is guided by the engagement of gear units 28 and 46 and link unit 22. As a result, during the extension movement of arms 18 and 20, lower end 50 of arm 20 is guided to revolve around shaft 40 provided on arm 18 in a clockwise direction when viewed from the right side. In this way, link unit 22 connects arms 18 and 20 so that they can be bent and extended between an extended position and a bent position, and gear units 28 and 46, together with link unit 22, guide the bending and extension movement of arms 18 and 20.

[0067] As the arms 18 and 20 extend from the bent position to the extended position, the lever portion 58 rotates relative to the arm 18 around the central axis of the shaft 40 in the clockwise direction as viewed from the right side, from the second relative position RP2 to the first relative position RP1. Here, in this embodiment, as described above, the assisting force generation mechanism 100 generates the assisting force Fa (specifically, the assisting force Fa1 or Fa2) to the lever portion 58 disposed at the second relative position RP2. 12 ) is added.

[0068] As a result, the lever portion 58 is urged from the second relative position RP2 toward the first relative position RP1, and as a result, the lower end portion 50 of the arm 20 is urged to revolve clockwise around the central axis of the shaft 40 via the link portion 22 as viewed from the right side. In this way, the assist force generation mechanism 100 applies the assist force Fa to the lever portion 58, thereby urging the arms 18 and 20 from the bent position toward the extended position.

[0069] In this way, the assistive orthosis 10 can assist the body B in standing up from a crouching position to an upright position by using the assistive force Fa generated by the assistive force generation mechanism 100. As a result, the body B can stand up more easily. Then, the body B transitions to the upright position shown in FIG. 1, and the arms 18 and 20 return to the extended positions.

[0070] As described above, in this embodiment, the assist force generation mechanism 100 includes the first biasing portion 104 and the second biasing portion 108 arranged side by side, the slider 110 movably provided between the first biasing portion 104 and the second biasing portion 108, and the locking portion 112 movable between an engagement position P1 that engages with the slider 110 and prohibits movement of the slider 110 relative to the second biasing portion 108, and a non-engagement position P2 that releases the engagement and allows the movement of the slider 110.

[0071] When the locking portion 112 is disposed in the engagement position P1, the assisting force generating mechanism 100 generates an assisting force Fa1 by the action of the first biasing portion 104 (FIG. 13). On the other hand, when the locking portion 112 is disposed in the disengagement position P2, the assisting force generating mechanism 100 generates an assisting force Fa2 by the action of the first biasing portion 104 and the second biasing portion 108. 12 (Figure 14)

[0072] According to this configuration, by selectively disposing the locking portion 112 at the engagement position P1 or the non-engagement position P2, the auxiliary force Fa generated by the auxiliary force generating mechanism 100 is divided into the auxiliary force Fa1 and the auxiliary force Fa 12 This allows the assist force Fa to be varied depending on the application.

[0073] In this embodiment, the assist force generating mechanism 100 further includes an actuator 114 that drives the locking part 112 between the engagement position P1 and the non-engagement position P2. According to this configuration, the locking part 112 is placed at the engagement position P1 or the non-engagement position P2 by the operation of the actuator 114, and the assist force Fa is divided into the assist force Fa1 and the assist force Fa2. 12 You can switch between

[0074] In this embodiment, the locking portion 112 is provided to be rotatable about an axis A6 that is parallel to the moving direction of the slider 110 between an engagement position P1 and a disengagement position P2. The actuator 114 is provided to be rotatable about an axis A7 that is perpendicular to the axis A6, and includes a rotating portion 118 that engages with the locking portion 112 (specifically, the engaging portion 112c), and a power unit 120 that rotates the rotating portion 118 to rotate the locking portion 112 between the engagement position P1 and the disengagement position P2 via the rotating portion 118.

[0075] According to this configuration, the actuator 114 can place the locking part 112 at the engagement position P1 or the disengagement position P2 by rotating the rotating part 118 using the power part 120. This allows the locking part 112 to be moved to the engagement position P1 or the disengagement position P2 with a relatively small driving force, and the configuration of the rotating part 118 and the locking part 112 can be made compact.

[0076] Furthermore, in this embodiment, the power unit 120 has shape memory alloys 130a and 130b that are connected to the rotating unit 118 and expand and contract in response to an electric current, thereby rotating the rotating unit 118. Here, the shape memory alloys 130a and 130b are relatively lightweight and can generate a driving force that rotates the rotating unit 118 without generating noise. Therefore, the weight of the assisting force generation mechanism 100 can be reduced, and the operation of the assisting force generation mechanism 100 can be made quieter.

[0077] In this embodiment, the slider 110 has a slider body 110a and a claw portion 110b protruding outward from the slider body 110a. The locking portion 112 has a ring portion 112a that surrounds the slider body 110a and is rotatable between an engagement position P1 and a disengagement position P1, and a groove portion 112b formed in the ring portion 112a so as to extend parallel to the movement direction of the slider 110 (i.e., the axis A6).

[0078] When the ring portion 112a is positioned at the engagement position P1, the claw portion 110b engages with the ring portion 112a of the lock portion 112, thereby prohibiting movement of the slider 110 relative to the second biasing portion 108. On the other hand, when the ring portion 112a is positioned at the non-engagement position P2, the claw portion 110b enters the groove portion 112b, thereby permitting the movement of the slider 110. With this configuration, the lock portion 112 can prohibit or permit movement of the slider 110 with a relatively simple configuration. Therefore, the lock portion 112 can make the configuration of the slider 110 compact.

[0079] Furthermore, in this embodiment, the first biasing unit 104 includes a spring having a first spring constant k1, and the second biasing unit includes a spring having a second spring constant k2 (≠k1) that is different from the first spring constant k1. With this configuration, by using two springs with different spring constants, it is possible to easily configure the first biasing unit 104 and the second biasing unit 108 that can generate forces of different magnitudes. Therefore, the manufacturing cost of the assist force generation mechanism 100 can be reduced.

[0080] Furthermore, in this embodiment, the first biasing portion 104 can generate a biasing force F1 (>F2) greater than that of the second biasing portion 108. More specifically, by setting the first spring constant k1 of the first biasing portion 104 to a value greater than the second spring constant k2 of the second biasing portion 108, the biasing force F1 (=k1·x) of the first biasing portion 104 can be made greater than the biasing force F2 (=k2·x) of the second biasing portion 108. According to this configuration, by selectively disposing the locking portion 112 at the engagement position P1 or the non-engagement position P2 depending on the application, the auxiliary force Fa can be set to either an auxiliary force Fa1 or an auxiliary force Fa2 that is significantly smaller than the auxiliary force Fa1. 12 You can switch between

[0081] Furthermore, in this embodiment, the assistive orthosis 10 includes an arm 18 attached to a part B2 (specifically, the shin) of the body B, an arm 20 attached to a part B1 (specifically, the thigh) of the body B, a link part 22 that connects the arms 18 and 20 so that they can be bent and extended between an extended position and a bent position, and an assistive force generation mechanism 100 that applies an assistive force Fa to the link part 22 (specifically, the lever part 58) to urge the arms 18 and 20 from the bent position toward the extended position. With this configuration, it is possible to realize an assistive orthosis 10 that can switch the assistive force Fa depending on the application, as described above.

[0082] The actuator 114 may have an operation unit (for example, a switch, a push button, or a touch panel) that turns the current to the SMA 130b on or off, and the user of the assistive device 10 may manually operate the operation unit to turn the current to the SMA 130b on or off. In this case, the user can manually operate the actuator 114 to arbitrarily position the locking unit 112 at the engaged position P1 or the disengaged position P2.

[0083] In this embodiment, the power unit 120 (FIG. 10) has been described as having a pair of SMAs 130a and 130b. However, this is not limiting, and the power unit 120 may have, for example, an elastic filament (e.g., a rubber band) instead of the SMA 130a. Even in this case, the power unit 120 can achieve the rotational movement of the rotation unit 118 as shown in FIGS. 10 and 11.

[0084] A sliding material with a low coefficient of friction (e.g., resin) may be provided at the contact portion between side surface 58a of lever portion 58 and bottom portion 106a of housing 106. With this configuration, side surface 58a of lever portion 58 can slide more smoothly on bottom portion 106a when arms 18 and 20 bend and stretch between the bent position and the extended position.

[0085] Furthermore, while the arms 18 and 20 move from the extended position to the bent position, the side surface 58a abuts against the bottom portion 106a while sliding against it, and the curved shape of the side surface 58a may be determined so that the normal direction of the side surface 58a at the point of abutment between the side surface 58a and the bottom portion 106a is approximately parallel to the axis A2 (or A6).

[0086] According to this configuration, the side surface 58a can constantly and effectively apply a force to the bottom portion 106a in the first direction D1 while the arms 18 and 20 move from the extended position to the bent position. This effectively compresses the first biasing portion 104 and the second biasing portion 108. Meanwhile, the first biasing portion 104 and the second biasing portion 108 can apply a force to the side surface 58a of the lever portion 58 in the second direction D2 that is parallel to the normal direction of the side surface 58a, thereby effectively biasing the lever portion 58 toward the first relative position RP1.

[0087] The assistive orthosis 10 may have a pair of mechanical units 12, one of which may be disposed on the left side of the thigh B1, shin B2, and knee joint B3, while the other of which may be disposed on the right side of the thigh B1, shin B2, and knee joint B3. In this case, the pair of mechanical units 12 may have a bilaterally symmetrical structure.

[0088] Furthermore, the configuration of the assistive force generation mechanism 100 described above is one example, and various modifications can be made. For example, the actuator 114 may be omitted from the assistive force generation mechanism 100, and the user may manually place the locking part 112 in the engaged position P1 or the disengaged position P2. Furthermore, the actuator 114 may have a motor (for example, a micromotor) that rotates the rotating part 118, instead of the SMAs 130a and 130b.

[0089] Also, the locking portion 112 is not limited to a form having a ring portion 112a and a groove portion 112b. For example, the locking portion 112 may have a pin that moves forward and backward in the radial direction with respect to the slider 110 and is detachably engaged with an engagement hole formed in the slider 110, or may have any other structure capable of prohibiting the movement of the slider 110 with respect to the second biasing portion 108 (or the housing 106).

[0090] In the above-described embodiment, the case where the first biasing portion 104 can generate a biasing force F1 (> F2) larger than that of the second biasing portion 108 has been described. However, the present invention is not limited to this, and the first biasing portion 104 may be configured to generate the same biasing force F1 (= F2) as that of the second biasing portion 108, or a biasing force F1 (< F2) smaller than that of the second biasing portion 108 with respect to a common displacement amount x.

[0091] In this case, the first spring constant k1 may be set to the same value as the second spring constant k2 or a value smaller than the second spring constant k2. Note that at least one of the first biasing portion 104 and the second biasing portion 108 is not limited to a spring, and may have any structure capable of generating a biasing force acting in the second direction D2, such as a pneumatic cylinder or a pair of magnets repelling each other.

[0092] Next, referring to FIGS. 15 and 16, an auxiliary device 70 according to another embodiment will be described. The auxiliary device 70 is different in that it further includes a control unit 72, a sensor 74 (FIG. 16), and a power source 76 in addition to the above-described auxiliary device 10. In FIG. 15, the mounting bands 14 and 16 are not shown for ease of understanding. The power source 76 is fixed to the arm 18 (specifically, the second portion 38 of the main body portion 26) and supplies power to the control unit 72 and the power unit 120 (specifically, the SMA 130b) of the actuator 114. For example, the power source 76 may have a dry battery.

[0093] The sensor 74 detects the posture of the body B. Here, as shown in Fig. 17, when the body B walks up a slope, the right leg B11 and the left leg B12 are alternately extended forward on the slope (i.e., upward on the slope). Fig. 17 shows a posture in which the right leg B11 is extended forward on the slope.

[0094] In this posture, the flexion angle between the thigh B1 and shin B2 of the right leg B11 is smaller than the flexion angle between the thigh B1 and shin B2 of the left leg B12, and the thigh B1 and shin B2 of the right leg B11 are bent more deeply, while the thigh B1 and shin B2 of the left leg B12 are substantially extended.

[0095] In this embodiment, the sensor 74 detects the posture of the leg B11 according to the degree of bending. As an example, the sensor 74 has a pressure sensor 74A provided on the sole B4 of the leg B11. Here, when the body B is walking on a slope, the pressure applied to the sole B4 changes depending on whether the leg B11 is positioned in the front of the slope (i.e., when the thigh B1 and shin B2 of the leg B11 are deeply bent) or when the leg B11 is positioned in the rear of the slope (i.e., when the thigh B1 and shin B2 of the leg B11 are extended). The pressure sensor 74A detects the pressure that changes in accordance with the posture of the leg B11 as detection data α.

[0096] As another example, the sensor 74 has a gyro sensor 74B provided on the instep B5 of the leg B11. When the body B is walking on a slope and the leg B11 moves back and forth on the slope, the inclination angle of the instep B5 changes accordingly. The gyro sensor 74B detects the inclination angle that changes in accordance with the posture of the leg B11 as detection data α.

[0097] As yet another example, the sensor 74 includes an angle sensor 74C that measures the flexion angle of the knee joint B3 or the ankle B6 of the leg B11. When the body B is walking on a slope, the flexion angle of the knee joint B3 or the ankle B6 changes depending on whether the leg B11 is positioned at the front or rear of the slope. The angle sensor 74C detects this flexion angle, which changes depending on the posture of the leg B11, as detection data α.

[0098] As yet another example, the sensor 74 includes motion capture devices 74D provided on at least two of the thigh B1, shin B2, knee joint B3, sole B4, instep B5, and ankle B6 of the leg B11. The motion capture devices 74D detect the posture of the leg B11 as detection data α.

[0099] In this way, the sensors 74 (e.g., pressure sensor 74A, gyro sensor 74B, angle sensor 74C, motion capture 74D) detect the posture of the body B (specifically, leg B11) as detection data α (e.g., pressure, tilt angle, flexion angle, posture data) and supply the detection data α to the control unit 72.

[0100] The control unit 72 has, for example, a processor (CPU, GPU, etc.) and memory (RAM, ROM, etc.), and is fixed to the arm 18 (specifically, the second part 38 of the main body 26). The control unit 72 controls the actuator 114 to move the locking part 112 between the engagement position P1 and the disengagement position P2 based on the detection data α of the sensor 74. A control method of the actuator 114 executed by the control unit 72 will be described below.

[0101] The control unit 72 determines whether the leg B11 has moved forward or backward on the slope based on the detection data α of the sensor 74. For example, the control unit 72 determines whether the leg B11 has moved forward or backward on the slope based on the detection data α and the threshold value α th By comparing this threshold value α with the threshold value α , it is determined whether the leg B11 has moved forward or backward on the slope. this determined in advance by a method such as an experiment or a simulation as a value corresponding to the detection data α detected by the sensor 74 when the leg B11 moves forward or backward on the slope.

[0102] When the control unit 72 determines that the leg B11 has moved forward on the slope, it operates the power unit 120 of the actuator 114 (specifically, applies a current from the power supply 76 to the SMA 130b) to place the lock unit 112 in the disengagement position P2. As a result, when the leg B11 is extended forward on the slope as shown in FIG. 17, the assist force generation mechanism 100 generates the assist force Fa 12 The assistive device 10 generates the assistive force Fa 12 This assists the bending and stretching of the leg B11 during walking.

[0103] On the other hand, when the control unit 72 determines that the leg B11 has moved backward on the slope (see leg B12 in FIG. 17), it operates the power unit 120 of the actuator 114 to place the lock unit 112 at the engagement position P1. As a result, when the leg B11 is at the rear of the slope, the assist force generation mechanism 100 generates an assist force Fa1 by the action of the first biasing unit 104, and the assist orthosis 10 uses this assist force Fa1 to assist the bending and stretching movement of the leg B11 while walking. In this way, the control unit 72 controls the assist force Fa according to the posture of the leg B11 walking on the slope (specifically, the degree of bending of the leg B11). 12 and the assist force Fa1.

[0104] As described above, in this embodiment, the assistive device 70 includes the control unit 72 that controls the operation of the actuator 114 that drives the locking portion 112 between the engagement position P1 and the disengagement position P2. According to this configuration, the assistive force Fa generated by the assistive force generation mechanism 100 is 12 and the auxiliary force Fa1.

[0105] In this embodiment, the assistive orthosis 70 further includes a sensor 74 that detects the posture of the body B (specifically, the leg L1). The control unit 72 controls the actuator 114 to move the locking unit 112 between the engagement position P1 and the disengagement position P2 based on the detection data α of the sensor 74 (for example, data on pressure, tilt angle, bending angle, and posture).

[0106] According to this configuration, the assist force Fa generated by the assist force generation mechanism 100 is adjusted to the assist force Fa 12 Specifically, as described above, when the leg B11 is in the front of the slope (in other words, when the thigh B1 and the shin B2 of the leg B11 are deeply bent), a smaller assist force Fa 12 The assist force generating mechanism 100 generates a larger assist force Fa1. This allows the deeply bent leg B11 to be flexibly supported. On the other hand, when the leg B11 is at the rear of the slope (in other words, when the thigh B1 and shin B2 of the leg B11 are extended), the assist force generating mechanism 100 generates a larger assist force Fa1. This allows the leg B11 to be firmly supported.

[0107] In this embodiment, the function of the assistive orthosis 70 attached to the right leg B11 has been described, but it should be understood that two assistive orthosis 70 may be attached to the left leg B11 and the right leg B12, respectively. In this case, the mechanism unit 12 of the assistive orthosis 70 attached to the left leg B12 and the mechanism unit 12 of the assistive orthosis 70 attached to the right leg B11 may have structures that are bilaterally symmetrical to each other.

[0108] In addition, when the control unit 72 determines that the leg B11 has moved forward on the slope, it may operate the actuator 114 to place the locking unit 112 in the engagement position P1, and when it determines that the leg B11 has moved backward on the slope, it may operate the actuator 114 to place the locking unit 112 in the non-engagement position P2.

[0109] 18, even when the body B is walking across a slope, the control unit 72 may control the actuator 114 to move the locking unit 112 between the engagement position P1 and the disengagement position P2 based on the detection data α of the sensor 74. For example, the control unit 72 determines whether the right leg B11 is on the lower side or the upper side of the slope based on the detection data α.

[0110] 18, the right leg B11 is on the lower side of the slope. In this case, the control unit 72 of the assistive orthosis 70A attached to the right leg B11 determines that the leg B11 is on the lower side of the slope based on the detection data α, and controls the actuator 114 to place the locking unit 112 of the assistive orthosis 70A at the engagement position P1. In this way, when the leg B11 is on the lower side of the slope, the assistive force generating mechanism 100 of the assistive orthosis 70A generates an assistive force Fa1 through the action of the first biasing unit 104, and the assistive orthosis 70A uses this assistive force Fa1 to assist the bending and stretching movement of the leg B11 during walking.

[0111] Conversely, when the control unit 72 of the assistive orthosis 70A determines based on the detection data α that the leg B11 is on the upper side of the slope, it controls the actuator 114 to place the locking unit 112 of the assistive orthosis 70A in the non-engagement position P2. In this way, when the leg B11 is on the upper side of the slope, the assistive force generating mechanism 100 of the assistive orthosis 70A generates the assistive force Fa 12 The auxiliary device 70A generates the auxiliary force Fa 12 This assists the bending and stretching of the leg B11 during walking.

[0112] 18, when the leg B11 is on the lower side of the slope, the thigh B1 and shin B2 of the leg B11 are in a relatively extended state. In this case, the assistive orthosis 70A causes the assistive force generating mechanism 100 to generate a larger assistive force Fa1, thereby enabling the assistive orthosis 70A to firmly support the extended leg B11.

[0113] On the other hand, when the leg B11 is on the upper side of the slope, the thigh B1 and the shin B2 of the leg B11 are bent relatively deeply. In this case, the assisting device 70A applies a smaller assisting force Fa 12 The assist force generating mechanism 100 generates the assist force, which enables the bent leg B11 to be flexibly supported.

[0114] In addition, the control unit 72 of the assistive device 70B attached to the left leg B12 may also control the actuator 114 based on the detection data α of the sensor 74 to position the locking unit 112 at the engagement position P1 when the leg B12 is on the lower side of the slope, and to position the locking unit 112 at the non-engagement position P2 when the leg B12 is on the upper side of the slope, as shown in Figure 18.

[0115] In the above-described embodiment, the control unit 72 and the power source 76 are fixed to the arm 18 (second part 38). However, this is not limiting, and at least one of the control unit 72 and the power source 76 may be fixed to the arm 20 or the link part 22, or may be held by the user without being fixed to the mechanism part 12.

[0116] In the above-described embodiments, the assistive devices 10 and 70 are described as being attached to the thigh B1 and shin B2 to assist in the flexion and extension movements of the thigh B1 and shin B2. However, this is not limiting, and the assistive devices 10 and 70 may be attached to the forearm and upper arm of human body B, for example, to assist in the flexion and extension movements of the forearm and upper arm. While the present disclosure has been described above through the embodiments, the above-described embodiments do not limit the invention according to the claims. [Explanation of symbols]

[0117] 10,70,70A,70B Assistive devices 12 Mechanism 14,16 Wearing band 18,20 Arm 22 Link section 72 Control Unit 74 Sensors 100 Auxiliary force generation mechanism 104 first biasing portion 108 second biasing portion 110 Slider 110a Slider body 110b Claw part 112 Rock Club 112a Ring section 112b Groove 114 Actuator 118 Rotating part 120 Power section 130a,130b Shape memory alloy (SMA)

Claims

1. An assist force generating mechanism that generates an assist force for an assist device that assists bending and stretching movements of the body, a first biasing portion and a second biasing portion arranged side by side; a slider movably provided between the first biasing portion and the second biasing portion; a locking portion that is movable between an engagement position that engages with the slider and prohibits movement of the slider relative to the second biasing portion and a non-engagement position that releases the engagement and allows movement of the slider, an auxiliary force generating mechanism that generates the auxiliary force by the action of the first biasing portion when the locking portion is disposed in the engaged position, and generates the auxiliary force by the action of the first biasing portion and the second biasing portion when the locking portion is disposed in the disengaged position.

2. The assist force generating mechanism according to claim 1 , further comprising an actuator that drives the locking portion between the engaged position and the disengaged position.

3. the locking portion is provided rotatable about a first axis parallel to a moving direction of the slider between the engagement position and the disengagement position, The actuator is a rotating portion that is provided rotatably about a second axis that is perpendicular to the first axis and that engages with the locking portion; The assist force generating mechanism according to claim 2 , further comprising: a power unit that rotates the rotation unit to rotate the lock unit between the engaged position and the disengaged position via the rotation unit.

4. 4. The assist force generation mechanism according to claim 3, wherein the power unit has a shape memory alloy connected to the rotating unit and expanding and contracting in response to an electric current to rotate the rotating unit.

5. The slider has a slider body and a claw portion protruding outward from the slider body, The locking portion is a ring portion that surrounds the slider body and is rotatable between the engagement position and the disengagement position; and a groove portion that is formed in the ring portion so as to extend parallel to the movement direction of the slider, 2. The assist force generation mechanism according to claim 1, wherein when the ring portion is disposed at the engagement position, the claw portion engages with the ring portion to prohibit movement of the slider, whereas when the ring portion is disposed at the disengagement position, the claw portion enters the groove portion to allow movement of the slider.

6. the first biasing portion includes a spring having a first spring constant; The assist force generating mechanism according to claim 1 , wherein the second biasing portion includes a spring having a second spring constant different from the first spring constant.

7. The assist force generation mechanism according to claim 1 , wherein the first biasing portion is capable of generating a biasing force greater than that of the second biasing portion.

8. An assistive orthosis that assists in bending and stretching movements of a first part and a second part of a body that are connected via a joint, a first arm attached to the first portion and a second arm attached to the second portion; a link portion that connects the first arm and the second arm so as to be bendable between an extended position and a bent position; an assistive force generating mechanism according to claim 1 that applies an assistive force to the link portion to urge the first arm and the second arm from the bent position toward the extended position.

9. 9. The assistive device of claim 8, further comprising a controller that controls operation of an actuator that drives the locking portion between the engaged and disengaged positions.

10. Further comprising a sensor for detecting the posture of the body; The assistive device according to claim 9 , wherein the control unit controls the actuator to move the locking portion between the engaged position and the disengaged position based on detection data from the sensor.

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