Motion assistance device

Abstract

This motion assistance device comprises: a base body; a drive unit connected to the base body; and a conversion mechanism that is attachable to and detachable from a target finger and is configured to be capable of receiving a driving force from the drive unit and converting rotational motion about an axis intersecting the long axis of the finger into motion including flexion and extension of the finger.

Description

Movement support device

[0001] The present invention relates to a motion assistance device. The present invention claims priority to U.S. Provisional Application No. 63 / 688,872, filed in the United States on August 30, 2024, the contents of which are incorporated herein by reference.

[0002] In recent years, devices for assisting finger movement have been increasingly introduced for finger rehabilitation. Examples of such devices include Patent Documents 1 to 5. The upper limb finger rehabilitation system disclosed in Patent Document 1 includes a movement detection device attached to the healthy upper limb finger and detecting changing joint angles, a control device that receives joint angle data and generates control data, and a rehabilitation training device that passively moves the affected upper limb finger based on the control data. The rehabilitation support device disclosed in Patent Document 2 includes a voice input means for inputting the trainee's voice, a finger exercise means that causes the trainee's fingers to perform rehabilitation exercises, and a control means that controls the rehabilitation exercises. Patent Document 3 discloses a finger assist actuator that includes multiple twisted string actuators, a finger cot member attached to cover the tip of the finger, and multiple ring members attached near the finger joints. The hand rehabilitation device disclosed in Patent Document 4 includes an orthosis attached to partially cover the patient's hand and forearm, a flexible rod with a combination of exercises that can be freely set by the operator, an element for sliding and supporting the flexible rod, finger socks with thimbles, a fixed rod fixed to the thimble and hingedly connected to the flexible rod, a control unit with means for moving the flexible rod, means for adjusting the tension of the rod, and means for adjusting the rehabilitation device to fit the anatomical characteristics of the hand.The finger joint rehabilitation device disclosed in Patent Document 5 includes a bellows, a bottomed cylindrical body that is arranged across the finger joints along the side of the finger in the extension direction and is flexible in the axial direction and flexible in the bending direction, a pipe communicating with the bellows, and an internal pressure adjustment unit that discharges working fluid from the bellows through the pipe to create a negative internal pressure in the bellows, causing the bellows to contract and generate a force to support the finger joint extension movement.

[0003] Japanese Patent Laid-Open No. 2004-267254 Japanese Patent Laid-Open No. 2010-17349 Japanese Patent Laid-Open No. 2010-82342 Japanese Patent Laid-Open No. 2013-529937 Japanese Patent Laid-Open No. 2015-171446

[0004] However, the devices disclosed in Patent Documents 1 to 5 have a problem in that the configuration for assisting the movement of fingers, which have a complex structure, is complicated.

[0005] Therefore, an object of the present invention is to simplify the motion support device.

[0006] As a means for solving the above problems, an aspect of the present disclosure has the following configuration: (1) A movement assistance device according to an aspect of the present disclosure includes a base body, a drive unit connected to the base body, and a conversion mechanism that is detachable from a target finger and configured to receive a driving force from the drive unit and convert a rotational movement about an axis intersecting the long axis of the finger into a movement including flexion and extension of the finger.

[0007] (2) In the motion assistance device described in (1) above, the base may be disposed on the palm side of the hand holding the fingers.

[0008] (3) In the motion assistance device described in (1) or (2) above, the conversion mechanism may include a rotating member including at least one extension portion extending along the long axis of the finger and configured to enable the rotational movement, at least one connecting member configured to be detachable from the finger, and at least one moving member to which the connecting member is connected and configured to be movable along the extension portion.

[0009] (4) In the motion assistance device described in (3) above, the connecting member may be rotatably connected to the moving member so as to convert the rotational movement of the rotating member into a movement including flexion and extension of the finger.

[0010] (5) In the motion support device described in (3) above, each of the at least one extension portion, the at least one connecting member, and the at least one moving member may be provided on a finger other than the thumb, and may be provided to correspond to the index finger, middle finger, ring finger, and little finger.

[0011] According to the above aspect, simplification can be achieved.

[0012] 1 is a plan view of a motion support device according to an embodiment; FIG. 2 is a side view taken along arrow II in FIG. 1; FIG. 3 is a plan view taken along arrow III in FIG. 2; FIG. 4 is a side view taken along arrow IV in FIG. 3; FIG. 5 is a side view taken along arrow V in FIG. 3; FIG. 6 is a side view taken along arrow VI in FIG. 3; FIG. 7 is a perspective view of a 3D model of a motion support device according to an embodiment; FIG. 8 is a diagram showing the movement of the motion support device according to an embodiment during flexion; FIG. 9 is a diagram showing the experimental setup of an embodiment; FIG. 10 is a diagram showing the joint drive range of an embodiment; FIG. 11 is a diagram showing displacement during flexion at a joint angle (subject 1) during flexion and extension in an embodiment; FIG. 12 is a diagram showing displacement during extension at a joint angle (subject 1) during flexion and extension in an embodiment.

[0013] An embodiment of the present invention will be described below with reference to the drawings. In the following description, a motion assistance device constituting a robot for hand rehabilitation will be described as an example of a motion assistance device. This motion assistance device is used, for example, to restore motor function after cerebrovascular disease or the like.

[0014] In the following description, expressions indicating relative or absolute arrangements, such as "parallel," "orthogonal," "center," and "coaxial," do not only mean such arrangements or states in the strict sense, but also include arrangements or states in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. In the drawings used in the following description, the scale of each component may be changed as appropriate to make each component recognizable.

[0015] <Movement Support Device> Fig. 1 is a plan view of a movement support device 1 according to an embodiment. Fig. 2 is a side view taken along arrow II in Fig. 1. Fig. 3 is a plan view taken along arrow III in Fig. 2. Fig. 4 is a side view taken along arrow IV in Fig. 3. Fig. 5 is a side view taken along arrow V in Fig. 3. Fig. 6 is a side view taken along arrow VI in Fig. 3. Referring to Figs. 1 to 6 together, the movement support device 1 comprises a base 2, a drive unit 3, and a conversion mechanism 4.

[0016] <Base> The base 2 is a base portion of the motion assistance device 1. In this embodiment, the base 2 is placed on the palm side of the hand holding the fingers. The base 2 is formed to a size that can fit within the palm of the user's hand, for example.

[0017] The base body 2 comprises a rectangular parallelepiped base body 20, a first arm portion 21 provided at one longitudinal end of the base body 20, a second arm portion 22 provided at the other longitudinal end of the base body 20, and a drive side support portion 23 provided at one longitudinal end of the base body 20.

[0018] The base body 20 is the base portion of the base 2. The base body 20 is placed on the palm side of the hand holding the fingers. The base body 20 is formed to a size that fits within the palm of the user's hand, for example. The base body 20 may be configured to be fixed to the user's hand or arm with, for example, a band or the like.

[0019] The first arm 21 and the second arm 22 have the function of rotatably supporting the conversion mechanism 4 (base-side connecting shaft 42). The first arm 21 and the second arm 22 are, for example, arranged parallel to each other. When the base body 20 is placed on the palm side of the user, each of the first arm 21 and the second arm 22 extends in a direction intersecting (for example, perpendicular to) the longitudinal direction of the base body 20 so as to face the tip of the hand.

[0020] The drive-side support portion 23 is a portion that supports the drive unit 3. The portion of the drive-side support portion 23 opposite to the drive unit 3 is connected to the first arm portion 21. The drive-side support portion 23 is provided so as to bridge between the first arm portion 21 and the drive unit 3.

[0021] <Drive Unit> The drive unit 3 includes an actuator such as a motor. The drive unit 3 is connected to the base 2. The drive unit 3 is arranged on the side of the first arm. The drive unit 3 is linked to the drive-side support unit 23. The drive unit 3 is connected to the conversion mechanism 4 (base-side connecting shaft 42) via, for example, the output shaft of the motor. The drive unit 3 is arranged, for example, on the little finger side of the user. Alternatively, the drive unit 3 may be arranged in a position other than the little finger (for example, on the thumb side).

[0022] <Conversion Mechanism> The conversion mechanism 4 is detachable from the target finger. The conversion mechanism 4 is configured to receive a driving force from the drive unit 3 and convert a rotational movement about an axis intersecting the long axis of the finger into a movement including flexion and extension of the finger.

[0023] The conversion mechanism 4 includes a rotating member 40, at least one connecting member 45A, 45B, 45C, and 45D, and at least one moving member 46A, 46B, 46C, and 46D.

[0024] The rotating member 40 is configured to be capable of rotational movement relative to the base body 2. The rotating member 40 includes at least one extending portion 41A, 41B, 41C, 41D extending along the longitudinal axis of the finger. When the base body 2 is placed on the palm side of a user, the rotating member 40 extends in a direction intersecting (e.g., perpendicular to) the longitudinal direction of the base body 2, from the base side of the hand toward beyond the tips of the extended fingers (forward of the fingertip positions when the user extends the fingers straight).

[0025] The connecting members 45A, 45B, 45C, and 45D are configured to be detachable from the fingers. The connecting members 45A, 45B, 45C, and 45D are attached to the fingers with, for example, a rubber band or tape. The connecting members 45A, 45B, 45C, and 45D may be formed in a shape that allows the fingers to be inserted (e.g., a cylindrical shape), or a shape that allows the fingers to be pinched. Note that various methods can be used to connect the fingertips to the conversion mechanism 4, such as a button attachment via a glove, a hook-and-loop fastener, or a loose restraint using a relatively viscous material.

[0026] The connecting members 45A, 45B, 45C, and 45D each include a portion (e.g., a flat plate-shaped portion) that can be attached to and detached from the finger, and a portion that protrudes from the tip of the flat plate-shaped portion. The connecting members 45A, 45B, 45C, and 45D are rotatably connected to the moving members 46A, 46B, 46C, and 46D so that the rotational movement of the rotating member 40 can be converted into movements including flexion and extension of the finger. When the base body 20 is positioned on the palm side, the tip portions (protruding portions located in front of the finger tips) of the connecting members 45A, 45B, 45C, and 45D and the rear end portions (portions toward the finger tips) of the moving members 46A, 46B, 46C, and 46D are rotatably connected around an axis that intersects the long axis of the finger. The connection portions between the tip ends of the connecting members 45A, 45B, 45C, and 45D and the rear ends of the moving members 46A, 46B, 46C, and 46D constitute rotary joints RJ.

[0027] The moving members 46A, 46B, 46C, and 46D are connected to the connecting members 45A, 45B, 45C, and 45D and are configured to be movable along the extending portions 41A, 41B, 41C, and 41D. The moving members 46A, 46B, 46C, and 46D include a portion shaped (e.g., a pair of walls) to which the connecting members 45A, 45B, 45C, and 45D can be connected, and a portion shaped (e.g., a cylindrical shape) that can move along the extending portions 41A, 41B, 41C, and 41D. The pair of wall-shaped portions of the moving members 46A, 46B, 46C, and 46D are connected to the protruding portions of the connecting members 45A, 45B, 45C, and 45D so as to be rotatable about an axis that intersects the long axis of the finger, thereby forming a rotary joint RJ.

[0028] In the embodiment, at least one extension portion 41A, 41B, 41C, 41D, at least one connection member 45A, 45B, 45C, 45D, and at least one moving member 46A, 46B, 46C, 46D are provided on fingers other than the thumb, corresponding to the index finger, middle finger, ring finger, and little finger. In the embodiment, the device is configured to be able to assist movements including flexion and extension of at least one of the three joints of the fingers for the four fingers excluding the thumb.

[0029] The three joints of the fingers include the distal interphalangeal joint (DIP), which is the joint closest to the tip of the finger, the proximal interphalangeal joint (PIP), which is the joint second closest to the tip of the finger, and the metacarpophalangeal joint (MCP), which is the joint at the base of the finger.

[0030] Specifically, the rotating member 40 includes four extension portions 41A, 41B, 41C, and 41D, a base-side connecting shaft portion 42 that connects the base portions (portions on the base 2 side) of the four extension portions 41A, 41B, 41C, and 41D together, and a tip-side connecting shaft portion 43 that connects the tip portions (portions on the opposite side from the base 2 side) of the four extension portions 41A, 41B, 41C, and 41D together.

[0031] The four extensions 41A, 41B, 41C, and 41D are provided to correspond to the index finger, middle finger, ring finger, and little finger. The extensions 41A, 41B, 41C, and 41D are formed in a shape (e.g., a cylindrical shape) that follows the long axis of the finger. The four extensions 41A, 41B, 41C, and 41D are arranged at intervals from one another in a planar view. The four extensions 41A, 41B, 41C, and 41D are arranged parallel to one another in a planar view.

[0032] The base-side connecting shaft 42 extends in a direction intersecting the long axis of the finger. In plan view, the base-side connecting shaft 42 is formed in a shape (e.g., a cylindrical shape) that extends in a direction intersecting (e.g., perpendicular to) the extending portions 41A, 41B, 41C, and 41D. The outer longitudinal end of the base-side connecting shaft 42 is rotatably supported with respect to each of the arms 21 and 22.

[0033] The tip-side connecting shaft 43 extends in a direction intersecting the long axis of the finger. In plan view, the tip-side connecting shaft 43 is formed in a shape (e.g., a cylindrical shape) that extends in a direction intersecting (e.g., perpendicular to) the extending portions 41A, 41B, 41C, and 41D. In plan view, the tip-side connecting shaft 43 is arranged parallel to the base-side connecting shaft 42. When the movement assistance device 1 is in use, the tip-side connecting shaft 43 is arranged forward of the fingertip position when the user extends the finger straight.

[0034] Four connecting members 45A, 45B, 45C, and 45D are provided corresponding to the index finger, middle finger, ring finger, and little finger. Four moving members 46A, 46B, 46C, and 46D are provided corresponding to the index finger, middle finger, ring finger, and little finger. The four connecting members 45A, 45B, 45C, and 45D are provided corresponding to the four moving members 46A, 46B, 46C, and 46D. The four moving members 46A, 46B, 46C, and 46D are provided corresponding to the four extending portions 41A, 41B, 41C, and 41D.

[0035] The four connecting members 45A, 45B, 45C, and 45D are connected to the corresponding moving members 46A, 46B, 46C, and 46D by rotary joints RJ, and are configured to be able to independently convert the rotational movement of the rotating member 40 into movements including flexion and extension of the fingers. The four moving members 46A, 46B, 46C, and 46D are connected to the corresponding extending portions 41A, 41B, 41C, and 41D, respectively, so as to be able to move (for example, linearly along the longitudinal direction of the extending portions 41A, 41B, 41C, and 41D, and circumferentially around the longitudinal direction of the extending portions 41A, 41B, 41C, and 41D), and are configured to be able to independently displace.

[0036] <Example of Operation> For example, first, the base 2 is placed on the palm side of the user's hand, and the rotating member 40 is placed along the long axis of the finger. The finger tips are fixed to the connecting members 45A, 45B, 45C, and 45D, which are connected to the moving members 46A, 46B, 46C, and 46D via the rotary joint RJ. Next, the rotating member 40 is rotated by the drive unit 3, whose output shaft (rotating shaft) is connected to the base-side connecting shaft 42 that intersects (e.g., perpendicular to) the extending portions 41A, 41B, 41C, and 41D placed on the palm side, thereby assisting movements including flexion and extension of the three joints of the finger (DIP, PIP, and MCP).

[0037] For example, when assisting a movement including flexion of the three finger joints (DIP, PIP, MCP), the output shaft (rotation shaft) is rotated in one direction by the drive unit 3 while the finger is extended. For example, when assisting a movement including extension of the three finger joints (DIP, PIP, MCP), the output shaft (rotation shaft) is rotated in the other direction (the opposite direction to when assisting a movement including finger flexion) by the drive unit 3 while the finger is flexed. Note that when performing a movement that alternately repeats flexion and extension of the three finger joints (DIP, PIP, MCP), the drive unit 3 may alternately rotate the output shaft (rotation shaft) in one direction and the other direction.

[0038] <Effects> As described above, the movement assistance device 1 of the above embodiment includes the base 2, the drive unit 3 connected to the base 2, and the conversion mechanism 4 that is detachable from the target finger and configured to receive a driving force from the drive unit 3 and convert a rotational movement about an axis intersecting the long axis of the finger into a movement including flexion and extension of the finger. With this configuration, movement including flexion and extension of the finger can be assisted with a simple configuration including the base 2, the drive unit 3, and the conversion mechanism 4. Therefore, the movement assistance device 1 can be simplified.

[0039] In the above embodiment, the base body 2 is placed on the palm side of the hand holding the fingers. This configuration allows the base body 2 to fit within the palm, making it smaller and lighter, and easier to attach and detach. Furthermore, compared to when the base body 2 is placed on the back of the hand, it is easier to support movements including flexion and extension of the fingers.

[0040] In the above embodiment, the conversion mechanism 4 includes a rotating member 40 including at least one extending portion 41A, 41B, 41C, 41D extending along the longitudinal axis of the finger and configured to be capable of rotational movement, at least one connecting member 45A, 45B, 45C, 45D configured to be detachable from the finger, and at least one moving member 46A, 46B, 46C, 46D to which the connecting member 45A, 45B, 45C, 45D is connected and configured to be movable along the extending portion 41A, 41B, 41C, 41D. With this configuration, by arranging the extending portion 41A, 41B, 41C, 41D of the rotating member 40 in the palm along the longitudinal axis of the finger and attaching the connecting member 45A, 45B, 45C, 45D to the finger, the conversion mechanism 4 can be accommodated in the palm, thereby achieving a reduction in size and weight and enabling easy attachment and detachment. Furthermore, by applying a driving force from the drive unit 3 to the conversion mechanism 4 while the conversion mechanism 4 is held in the palm as described above, the moving members 46A, 46B, 46C, and 46D move along the extension portions 41A, 41B, 41C, and 41D, thereby assisting movements including flexion and extension of the three joints of the fingers (DIP, PIP, and MCP).

[0041] In the above embodiment, the connecting members 45A, 45B, 45C, and 45D are rotatably connected to the moving members 46A, 46B, 46C, and 46D so that the rotational movement of the rotating member 40 can be converted into movements including flexion and extension of the fingers. With this configuration, compared to when the connecting members 45A, 45B, 45C, and 45D are non-rotatably connected to the moving members 46A, 46B, 46C, and 46D (fixed in place), movements including flexion and extension of the three joints of the fingers (DIP, PIP, and MCP) can be more smoothly assisted.

[0042] In the above embodiment, at least one extension portion 41A, 41B, 41C, 41D, at least one connection member 45A, 45B, 45C, 45D, and at least one moving member 46A, 46B, 46C, 46D are provided for fingers other than the thumb, corresponding to the index finger, middle finger, ring finger, and little finger. With this configuration, it is possible to assist the movements of the four fingers excluding the thumb, including flexion and extension of the three joints of the fingers (DIP, PIP, MCP).

[0043] <Modifications> In the above embodiment, the base body is disposed on the palm side of the hand holding the fingers, but this is not limiting. For example, the base body may be disposed on the back side of the hand. The arrangement of the base body relative to the hand can be changed according to design specifications.

[0044] In the above embodiment, the conversion mechanism includes at least one extending portion extending along the long axis of the finger and a rotating member configured to be capable of rotational movement, at least one connecting member configured to be detachable from the finger, and at least one moving member connected to the connecting member and configured to be movable along the extending portion. However, this is not limited to this. For example, the conversion mechanism may not include the connecting member. For example, the moving member may include a portion configured to be detachable from the finger. The conversion mechanism may be configured to receive a driving force from the driving unit and convert rotational movement about an axis intersecting the long axis of the finger into movement including flexion and extension of the finger. The configuration of the conversion mechanism can be changed according to design specifications.

[0045] In the above embodiment, the connecting member is rotatably connected to the moving member so that the rotational movement of the rotating member can be converted into a movement including flexion and extension of the finger. However, this is not limited to this. For example, the connecting member may be non-rotatably connected to the moving member (fixed in a fixed position). The connection mode of the connecting member to the moving member can be changed according to the design specifications.

[0046] In the above embodiment, at least one extension portion, at least one connection member, and at least one moving member are provided on fingers other than the thumb, corresponding to the index finger, middle finger, ring finger, and little finger. While the above description is given by way of example, the present invention is not limited to this. For example, the extension portion, connection member, and moving member may be provided on the thumb. The manner in which the extension portion, connection member, and moving member are provided on the target fingers can be changed according to design specifications.

[0047] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and additions, omissions, substitutions, and other modifications to the configuration are possible within the scope of the spirit of the present invention, and the above-described embodiments can also be combined as appropriate.

[0048] The motion support device according to the above embodiment of the present invention will be specifically described below by showing examples. Note that the following examples are specific examples to which the present invention is applied, and are not intended to limit the present invention.

[0049] <Hand Exoskeleton Mechanism for Post-Stroke Rehabilitation> 15 million people worldwide suffer from stroke each year. Up to 88% of acute stroke patients experience hemiplegia. This paper introduces a novel hand rehabilitation device that uses a finger slider to convert rotational finger motion into linear finger motion. The mechanism is designed to effectively convert motor-driven single-degree-of-freedom motion into natural finger flexion and extension. This paper describes the concept design, prototype implementation, and preliminary evaluation.

[0050] 1. Introduction Globally, stroke is the second and third leading cause of death and disability (Reference [1]). Of the 15 million stroke patients per year (Reference [2]), 88% experience hemiplegia (Reference [3]). Of those with hemiplegia, 28% experience hand dysfunction (Reference [4]). In stroke rehabilitation, various treatments are designed to meet the individual needs of patients to restore motor function (Reference [5]). Currently, most rehabilitation training programs for upper limb hemiplegia require rehabilitation therapists to assist patients in voluntary movement. However, due to a shortage of rehabilitation therapists and available services, the majority of patients cannot receive the necessary treatment (Reference [6]).

[0051] Robot-assisted rehabilitation is widely recognized as a desirable solution to this problem. Hand rehabilitation robots are classified into three categories: end-effectors, rigid exoskeletons, and compliant exoskeletons. End-effectors control fingertip movement to flex and extend the fingers but are not portable. Exoskeletons are wearable and portable, flexing and extending all finger joints. End-effectors and rigid exoskeletons precisely control finger movement but are bulky and expensive, limiting training intensity and accessibility. Compliant exoskeletons can reduce weight and cost by using flexible materials and inflatable actuators. However, they have limited range of motion (ROM), and their soft structure prevents measurement of the patient's intentional movement and the implementation of feedback control.

[0052] Previous studies have either been too large and complex in their mechanical designs or have limited ROM and movement measurement capabilities.To address these issues, this study designed, prototyped, and evaluated a new hand rehabilitation device that employs a simple mechanism that can assist natural finger flexion and extension, is compact, lightweight, has a relatively wide range of motion, and can measure the patient's intentional movements.

[0053] <2. Mechanism> To develop a hand rehabilitation device that is compact, simple, capable of measuring the patient's intentional movements, and has a relatively wide range of motion, we designed a new mechanism using a finger slider that effectively converts the rotational movement of the hand driven by a motor into natural flexion and extension movements of the fingers.

[0054] 2.1 Concept Fingers have a complex structure, with three joints—the DIP joint, the PIP joint, and the MCP joint—connected in a continuous fashion for flexion and extension. Figure 7 is a perspective view of a 3D model of an example motion assist device. In the proposed design (see Figure 7), four fingers (from the index finger to the little finger, excluding the thumb) can be flexed and extended by a single motor positioned perpendicular to the fingers on the palm side. Figure 8 illustrates the motion of the example motion assist device during flexion. The fingertips are attached to a passive linear slider carriage via a rotational joint, enabling natural flexion and extension of each joint in accordance with the motor-induced motion (see Figure 8). This design is inspired by the fact that the three finger joints flex and extend when the fingers are relaxed and pushed or pulled along the fingers. The motion support device of the embodiment includes a base (corresponding to base body 2 in the embodiment), a servo motor (corresponding to drive unit 3 in the embodiment), four linear sliders (corresponding to extension units 41A, 41B, 41C, and 41D in the embodiment), four connectors (corresponding to connecting members 45A, 45B, 45C, and 45D in the embodiment), and four carriages (corresponding to moving members 46A, 46B, 46C, and 46D in the embodiment), and the four connectors are each connected to the corresponding carriage by a rotational joint (corresponding to rotary joint RJ in the embodiment).

[0055] 2.2 Prototype Implementation The implemented prototype is shown in Figure 9. Figure 9 illustrates the experimental setup for this example. The user's fingertips are fixed to the connector with medical tape. The connector is connected to a linear slider, and each finger can perform passive linear motion via a carriage. The linear slider is connected to a servo motor, which rotates the linear slider around an axis perpendicular to the long axis of the finger. The carriage slides freely on the linear slider, allowing it to slide independently in accordance with the rotational motion of the four fingers. This allows natural flexion and extension of the DIP, PIP, and MCP joints of the fingers. The linear slider allows the device to be easily attached to hands of various sizes. As described in the concept section, all mechanical parts are located on the palm side, making attachment and detachment simple and quick. The motor shaft is close to the fingers, minimizing the risk of interference between the device and the fingers.

[0056] The prototype was fabricated using a 3D printer (F170, Stratasys, USA). The spacing of each slide rail was determined based on the fingertip width of an average Japanese male (Reference [7]). The motor output specifications were carefully determined based on previous research on finger joint stiffness in stroke patients without severe spasticity. The study showed that a torque of 0.25 Nm was sufficient to extend the MCP joints of all four fingers to 0 degrees (Reference [8]), which applies to more than 95% of all stroke patients (Reference [4]). Accordingly, a servo motor (SEA410, NEWTC, Korea) with a torque output of 3.4 Nm and a weight of 40 g was selected. The prototype weighed 95.4 g, excluding the motor controller and cable.

[0057] <3. Experiment> To confirm that this device can provide natural flexion and extension movements of the fingers, a prototype was worn by a healthy subject and an evaluation was carried out.

[0058] 3.1 Methods Four healthy male subjects (ages 23-25) were recruited to evaluate the range of motion achievable with this device. Visual markers for motion capture were attached to the tip of the index finger, the palm, the DIP joint, the PIP joint, and the MCP joint (see Figure 9). The marker trajectories were recorded with a video camera (HDRCX680, Sony, Japan). During the experiment, the subjects wore the device and relaxed their fingers, allowing the device to flex and extend them. After the measurements, motion analysis was performed using Kinovea (Reference [9]) to obtain joint angles (DIP joint, PIP joint, and MCP joint).

[0059] 3.2 Results Figure 10 is a diagram showing the joint drive range of the example. Figure 10 shows the range of motion of each joint of all participants and the average. The motion analysis results of one participant are shown in Figures 11 and 12. Figure 11 is a diagram showing the displacement during flexion at the joint angle (subject 1) in flexion and extension in the example. Figure 12 is a diagram showing the displacement during extension at the joint angle (subject 1) in flexion and extension in the example. All joints show simultaneous and smooth flexion and extension.

[0060] 4. Conclusions This paper describes the design and evaluation of a handheld exoskeleton mechanism for post-stroke rehabilitation. Preliminary evaluation showed promising results. The advantages of the proposed device are its compact size, light weight, and ease of donning and doffing. We will continue to evaluate and refine the device design with the aim of developing it into a home rehabilitation device.

[0061] In addition to stroke, impaired finger motor function can also occur due to brain tumors, head trauma, spinal cord diseases, etc. Similarly, cases in which impaired finger flexion and extension occur are not limited to hemiplegia of the upper limbs. The movement assistance device disclosed herein can also be applied to rehabilitation for conditions other than hemiplegia of the upper limbs.

[0062] <References> [1] S. C. Cramer, et al.: “Stroke recovery and rehabilitation research: issues, opportunities, and the National Institutes of Health StrokeNet”, Stroke, vol. 48, no. 3, pp. 813-819, 2017. [2] “Stroke, Cerebrovascular accident”, https: / / www.emro.who.int / health-topics / stroke-cerebrovascular-accident / index.html [3] M. A. Foulkes, et al.: “The Stroke Data Bank: design, methods, and baseline characteristics”, Stroke, vol. 19, no. 5, pp.547-554, 1988. [4] D. K. Sommerfeld, et al.: “Spasticity after stroke: its occurrence and association with motor impairments and activity limitations”, Stroke, vol. 35, no. 1, pp. 134-139, 2004. [5] “Post-Stroke Rehabilitation”, https: / / www.stroke.org / en / life-after-stroke / stroke-rehab / post-stroke-rehabilitation [6] F. Gimigliano, et al.: “The World Health Organization" rehabilitation 2030: a call for action”, European Journal of Physical and Rehabilitation Medicine, vol. 53, no. 2, pp. 155-168, 2017. [7] “AIST Japanese hand dimension data”, https: / / www.airc.aist.go.jp / dhrt / hand / data / list.html [8] DG Kamper., et al.: “Quantitative features of the stretch response of extrinsic finger muscles in hemiparetic stroke”, Muscle & Nerve: Official Journal of the American Association of Electrodiagnostic Medicine, vol. 23, no. 6, pp. 954-961, 2000. [9] “Kinovea”, https: / / www.kinovea.org / .

[0063] REFERENCE SIGNS LIST 1 Motion support device 2 Base body 20 Base main body 21 First arm section 22 Second arm section 23 Drive side support section 3 Drive section 4 Conversion mechanism 40 Rotation member 41A, 41B, 41C, 41D Extension section 42 Base side connecting shaft section 43 Tip side connecting shaft section 45A, 45B, 45C, 45D Connection member 46A, 46B, 46C, 46D Moving member RJ Rotation joint

Claims

1. A movement assistance device comprising: a base; a drive unit connected to the base; and a conversion mechanism that is detachable from a target finger and configured to receive a driving force from the drive unit and convert rotational movement around an axis that intersects the long axis of the finger into movement including flexion and extension of the finger.

2. The movement assistance device according to claim 1, wherein the base is placed on the palm side of the hand holding the fingers.

3. The motion assistance device according to claim 1 or 2, wherein the conversion mechanism comprises: a rotating member including at least one extension portion extending along the long axis of the finger and configured to enable the rotational movement; at least one connecting member configured to be attachable to and detachable from the finger; and at least one moving member to which the connecting member is connected and configured to be movable along the extension portion.

4. The movement assist device according to claim 3, wherein the connecting member is rotatably connected to the moving member so as to be able to convert the rotational movement of the rotating member into a movement including flexion and extension of the finger.

5. The movement assistance device according to claim 3, wherein each of the at least one extension portion, the at least one connecting member, and the at least one moving member is provided on a finger other than the thumb, corresponding to the index finger, middle finger, ring finger, and little finger.

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