Exoskeleton device

Abstract

Described is an exoskeleton device for assisted movement of a body member. The exoskeleton is for assisted movement of a member comprising a plurality of joints. The exoskeleton includes a first rigid section and a second rigid section positioned at respectively opposite ends of the member and an intermediate rigid section between the first and second rigid sections and positioned between the joints in the member. The exoskeleton also includes a repeating M structure comprising a plurality of length segments, each length segment extending between a respective pair of said rigid sections, and a drive spring extending at least from the first rigid section to the second rigid section, along an external region of the repeating M-structure, the drive spring between extendable and retractable to actuate the exoskeleton. A stiffness of each length segment is selected based on an amount of force to be applied to the member.

Description

[0001] EXOSKELETON DEVICE

[0002] Technical Field

[0003] The present invention relates, in general terms, to an exoskeleton device for assisted movement of a member of the body (e.g. the upper or lower extremities, particularly the hand or fingers). More particularly, the present invention relates to, but is not limited to, flexible accordion-like structures for facilitating curved motions.

[0004] Background

[0005] This background is provided for generally presenting the context of the disclosure. Contents of this background section are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0006] Loss of bodily function particularly in the upper or lower extremities, such as the hand or fingers - whether due to neurological injury, muscular degeneration, age-related conditions or post-surgical recovery, can severely impact an individual's ability to perform essential daily tasks. Gripping, pinching and manipulating objects require coordinated finger flexion and extension (straightening from a condition of flexion), movements often compromised in patients with impaired motor control or muscular weakness in the hand.

[0007] Current assistive devices, for example for hand rehabilitation and functional support, range from passive splints to powered exoskeletons and orthoses. While some existing exoskeletons provide powered assistance, many are bulky, rigid or limited in adaptability to the user's hand anatomy. Soft robotic approaches have also emerged as a promising alternative. However, most rely on complex cable systems (e.g. ironHand, Kang et al., 2019), pneumatic or fluid-driven actuation (e.g., Yap et al., 2015, Polygerinos et aL, 2015) or a three-layered sliding spring mechanism (e.g. U.S. Pat. No. 10,028,880B2, US 2023 / 0157922A1), which may introduce challenges in assembly, portability, maintenance and precision control. These soft robotic approaches offer improved conformity to human anatomy and greater comfort during extended use. However, many of these systems lack the structural integrity to provide effective force transmission for dynamic finger movements. Moreover, few solutions provide a balance between mechanical robustness and flexibility, particularly for users requiring both therapeutic and functional support.

[0008] There remains a need for a hand exoskeleton that is compact, lightweight, and capable of providing controlled assistance in both flexion and extension of the fingers, while maintaining comfort and adaptability for the user.

[0009] Summary

[0010] The present invention relates to a customizable soft accordion-like structured exoskeleton device and a sliding spring, also referred to as a driving spring blade, to facilitate flexion, extension, and / or bending. As a primary application, it is implemented in the context of a hand exoskeleton to assist finger flexion and extension.

[0011] Described herein is an exoskeleton for assisted movement of a member comprising a plurality of joints, comprising: a plurality of rigid sections including a first rigid section and a second rigid section positioned at respectively opposite ends of the member and at least one intermediate rigid section between the first and second rigid sections and positioned between neighbouring ones of said joints in the member; a repeating M structure comprising a plurality of length segments, each length segment extending between a respective pair of said rigid sections; and a driving spring blade extending at least from the first rigid section to the second rigid section, along an external region of the repeating M-structure.

[0012] Another aspect of the present invention provides a robotic gripper comprising an end effector (e.g., in the form of an industrial robot arm, or a prosthetic socket) and the exoskeleton device, attached to the end effector to assist prehension of objects or interaction with the environment.

[0013] Brief description of the drawings

[0014] Embodiments of the present invention will now be described, by way of nonlimiting example, with reference to the drawings in which :

[0015] Figure la depicts an exoskeleton device for assisted movement of a member comprising a plurality of joints, according to various embodiments of the present invention.

[0016] Figure lb depicts an exploded view of the exoskeleton device for assisted movement of a member comprising a plurality of joints, according to various embodiments of the present invention.

[0017] Figure 2 illustrates an example application of the exoskeleton device as a finger component of a hand exoskeleton, according to various embodiments of the present invention.

[0018] Figure 3 shows a photographic example of the exoskeleton device, used in a collection to form an exoskeleton assembly, demonstrating its application in assisting finger flexion and extension, according to various embodiments of the present invention.

[0019] Detailed description

[0020] Various embodiments of the present invention provide an exoskeleton device for assisted movement of a member of the body (e.g. the upper or lower extremities, particularly the hand or fingers). Disclosed herein is a soft, compliant, and mechanically simple device designed to facilitate curved motion. The device features a modular and customizable outer frame or external region that translates linear input into controlled bending. The accordion-like geometry, achieved using a series of interconnected M-shaped structures, of the device enables precise control over flexion and extension behaviours, including adjustment of maximum bending angles and alignment of the centre of rotation for each individualized bending segment or length segment.

[0021] As a preferred embodiment of the invention, this design offers an effective and versatile solution for supporting finger joint flexion and extension, with potential applicability to other anatomical areas such as the wrist or elbow. The device is optimized for portability, featuring a compact, lightweight and fully wearable form factor. The mechanical simplicity, consisting mainly of hinge-like mechanisms along the outer region and a single spring blade (or, in some embodiments, multiple embedded spring blades) for motion transmission, improves both reliability and operational ease. The spring blade is internal of the structure of the exoskeleton (e.g., within slots), though it is on an external side of the repeating M-structure - i.e., the repeating M-structure is between the spring blade and the member (e.g., finger).

[0022] The present invention discloses an exoskeleton device for assisted movement of a member of the body comprising a plurality of joints. According to Figure la, the exoskeleton device (100) comprises a plurality of rigid sections including a first rigid section (102) and a second rigid section (104) positioned at respectively opposite ends of the member, and at least one intermediate rigid section (106) between the first and second rigid sections. Presently, there are two such intermediate sections (106), indicating suitability for use on a finger - since fingers, as opposed to thumbs, comprise a middle phalanx between distal and proximal phalanxes. The intermediate sections (106) are positioned between neighbouring ones of said joints in the member - e.g., joints of a finger. The exoskeleton device (100) further comprises a repeating M-structure (108) comprising a plurality of length segments (110). Each length segment (110) extends between a respective pair of said rigid sections (i.e. between the first rigid (102) section and a neighbouring intermediate rigid section (106), between neighbouring intermediate rigid sections (106) and, between the second rigid section (104) and a neighbouring intermediate rigid section (106)).

[0023] A torsional and transverse stiffness of each length segment may be set through the dimensions and thickness of said segment as well as the dimensions and thickness(es) of the M segment, in order to set the amount of force to be applied to the member. The member may comprise a finger of a hand and the plurality of rigid sections including one rigid section between neighbouring joints in the finger. It can be useful for such an exoskeleton device to be positioned on each finger and, potentially, also the thumb - the thumb would require only a single intermediate section (106). A collection of such exoskeleton devices forms an exoskeleton assembly.

[0024] As used hereinafter, the term "external region" denotes the outer frame or surface of the repeating M-structure (108) that is oriented away from the bodycontacting surface or opposite of the body-contacting surface. Thus, the member is on an internal side of the repeating M-structure, and the driving spring blade is on an external side of the repeating M-structure.

[0025] The exoskeleton device (100) further comprises a driving spring blade (112) which extends at least from the first rigid section (102) to the second rigid section (104), along an external region or side of the repeating M-structure (108). The driving spring blade (112) therefore passes through each intermediate section. The driving spring blade is driven by a motor (not shown). Where an exoskeleton assembly is used and is intended to apply considerable force - e.g., for object lifting tasks - it can be useful for all exoskeletons to be operated in unison. To that end a single motor may drive multiple driving spring blades of the exoskeleton devices. In other embodiments, where fine movements are desired - e.g., in artistic painting, writing or hand gesture creation - each driving spring blade may be driven by a separate motor.

[0026] Figure lb depicts an exploded view (100b) of the exoskeleton device showing main components of the device such as the repeating M-structure (108), one sliding spring or driving spring blade (112) and a screw (114) that connects the driving spring blade (112) to the structure. In particular, the distal end of the driving spring blade (being at the distal end of the member) is fixed to the first rigid section (102).

[0027] The driving spring blade (112) is extendable and retractable to actuate the exoskeleton. The driving spring blade extends through a plurality of individual slots or apertures formed along the external region of the repeating M-structure (108). These slots are configured to guide the blade (112), allowing it to slide, while also ensuring that the bend in the repeating M-structure (108) conforms to the bend of the driving spring blade (112). As the blade (112) advances, it enables controlled curvature of the exoskeleton device, thereby facilitating its flexion.

[0028] The term "repeating M-structure" can interchangeably be referred to as an M- lattice structure unless context dictates otherwise. The structure comprises a series of "M" shapes or "M" segments with a depth sufficient to resist bending transverse to the longitudinal direction.

[0029] The repeating M-structure (108) of the preferred embodiment is a structural lattice comprising a single layer of serially connected "M" shapes or "M" segments arranged in a horizontal orientation. In some embodiments, multiple layers may be used with the driving spring blade being external of all layers, or being positioned between layers. The "M" shape can be viewed as such from a side view depicted in Figure 2. Each "M" shape or "M" segment includes two angled V-shaped members, forming a continuous wave-like profile along the length of the lattice. The two angled members of the "M" segment, each have an extension (221 - in the exploded portion of Figure 2, also referred to as extension limiters as shown in exploded section 109a of Figure la) projecting externally of the M-shaped lattice structure. Each extension has a slot or aperture for receiving the driving spring blade (112) and guiding movement of the driving spring blade (112). Each extension 221 is shaped at its external end (the internal end being connected to the apex of the V-shaped angle structure of each M-shape) to provide a predetermined gap, which may be no gap, when the member is in an hyperextended position. The shape may result in a T- shaped extension when viewed from the side, as shown in Figure 2. Where there is no gap between the extensions when the member is hyperextended, the extensions resist further bending of the M-shaped lattice structure if an attempt is made to further withdraw or shorten the driving spring blade (112). This prevents excessive hyperextension of the joints of the member. Conversely, the opposite ends of the V-shaped structures are shaped so that the gap between neighbouring said opposite ends of the V-shaped structures limits the amount of flexion that can be applied (these ends, shown in exploded section 109b in Figure la, may also be referred to as flexion limiters). Thus, the shape of the exoskeleton device (100), and thus of the member to which it is attached, when in each of a position of maximum flexion and maximum extension is predetermined by the M-shaped lattice structure and extensions (221). In some embodiments, the gap between neighbouring ends of V-shaped structures differs between length segments, thereby allowing a joint to have a greater degree of flexion than another joint.

[0030] As shown in Figure la, a hinge-like mechanism may be implemented through flexible segments of the repeating M-structure (108) i.e. length segments (110), along dotted line (111). The M-shapes are connected in series such that the angles in the structure can increase and decrease - if the angles between legs of the M-shape increase on one side (internal or external) of each M-shape, then the angles between the legs, on the other side, necessarily decrease. The hingelike mechanism is configured to allow relative rotational movement between connected "M" segments. Moreover, while the angles in the M-shapes may vary, the length along an approximate midline of the repeating M-structure remains substantially unchanged.

[0031] The stiffness of each length segment (110) may be adjusted by selecting the type of material and dimensions. One length segment (110) may be formed from a different material from another length segment(s). This would allow for preferential flexion of one length segment relative to another length segment - i.e. a less stiff length segment will bend first, or to a greater degree, than a more stiff length segment. A similar effect can be achieved by varying the dimensions - e.g., the thickness - of M-shapes in one length segment relative to another length segment.

[0032] Along the dotted line (111), the length segments (110) should be flexible enough to allow rotational movement between connected "M" segments but should not be stretchable or compressible so to retain its original length. The structure should restrict linear elongation. This hinge-like mechanism or configuration allows the M lattice to bend and translates linear input through the driving spring blade (112) into controlled bending while preserving structural integrity and maintaining its overall length.

[0033] The repeating M structure (108) extends in a longitudinal direction over the joint and possesses a depth sufficient to resist bending in the traverse direction, adding to stability and control. At the same time, it is narrow enough along its length in the longitudinal direction, to allow and facilitate bending during flexion. For example, each exoskeleton device may be thinner in the transverse direction that the member to which it is attached.

[0034] The soft, compliant, accordion-like external region is the mechanical backbone, allowing the sliding spring or driving spring blade (112) to transfer linear motion into a flexion-like movement pattern. Extension and flexion limiters, as shown in Figure la (see exploded sections 109a, 109b), are integrated along both the external and internal regions of the length segments (110) respectively. As discussed above, the flexion limiters on the internal region prevents overbending or excess flexion of the "M"-lattice. The extension limiters on the external region prevent excessive hyperextension of the member. The "internal region" denotes the body- or member-contacting surface of the device.

[0035] In the context of the primary finger exoskeleton application, the sliding spring or driving spring blade (112) slides through the slots (at the external region) and pushes the first rigid section (102) of the finger exoskeleton. During this, the 'M' segments of repeating M-structure (108) maintain a constant linear length. Their geometry, however, allows for flexion and extension in the X-Y plane shown in Figure 2 while inhibiting flexion on the Z-direction. Due to the placement of the driving spring blade (112), as it is pushed through, the furthest surface from the human finger (external region) lengthens while the closest counterpart remains a constant length. This creates a natural, bio-mimetic, curvature in the structure, while maintaining sufficient elasticity to adapt to the shape of grasped objects.

[0036] The structure's parameters of the device may be fully tailored based on userspecific anatomical data including but not limited to finger length, phalangeal segment dimensions, and finger width. Such customization facilitates accurate alignment of the exoskeleton joints with the corresponding anatomical joints, thereby enhancing the effectiveness of assistive force transmission and mitigating the occurrence of parasitic forces resulting from misalignment. The respective density, thickness, angle, widths, heights and / or material (all of which control the stiffness) of the 'M' segments allow for the control of defining the maximum range of motion of each respective segment. The structure configuration inherently restricts linear elongation, a characteristic necessary to convert the linear translation of the spring into a corresponding bending motion. This induced bending translates into a torque applied to the respective joints to facilitate flexing of the attached human finger.

[0037] The accordion-like structure was developed so that its features are modular and adjustable. The 'M' segments or length segment (110) are connected with rigid sections (102, 104, 106) that overlay each respective phalange of the human finger. Each rigid section (with exception of the second rigid section) may comprise a strap - e.g. a hook and loop fastener - extendable around the member, to secure the rigid section to the member. This can adjust the flexion behaviour at independent joints (i.e., the distal interphalangeal joint (DIP joint), proximal interphalangeal joint (PIP joint), and metacarpophalangeal joint (MCP joint)). Placement of the length segment (110) and plurality of rigid sections (102, 104, 106) can therefore be predetermined or selected to determine flexion behaviour (e.g., force required for flexion, limit of flexion and / or extension, and so on). Manufacturing was also considered when designing the structure, resulting in a single component which can either be 3D printed or moulded.

[0038] Figure 2 illustrates an example application of the exoskeleton device as a finger component of a hand exoskeleton. From right to left, the customizable repeating "M" shapes (e.g. one "M" shape (220) is depicted in bold) of the repeating M- structure are mounted on an index finger, along the metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joint segments, respectively. The joint centres (218) are represented by black dots.

[0039] As shown in Figure 2, joint centres (218) are located between a respective pair of rigid sections (i.e. between the first rigid section (202) and a neighbouring intermediate rigid section (206), or between two neighbouring intermediate rigid sections (206) or between the second rigid section (204) and a neighbouring intermediate rigid section (206)). The rigid sections may align with bones of the index finger or the member. Similarly, rigid sections (202, 204, 206) are positioned between neighbouring joints in the members to which the exoskeleton is attached. Neighbouring joints are those that, when travelling along the repeating M structure from one end of the member to the opposite end of the member, are encountered with no other intervening joints. For example, for the joint between the metacarpal bone and proximal phalange of the index finger, a neighbouring joint would be between the proximal and middle phalanges of the index finger, but not between the middle and distal phalanges. Similarly, for the joint between the middle and distal phalanges, the neighbouring joint would be that between the proximal and middle phalanges.

[0040] The driving spring blade (112) is a cold-rolled stainless steel spring blade (or equivalent flexible material), which provides the requisite strength and stiffness to convert a longitudinal input force— such as that generated by a linear actuator, rack-and-pinion mechanism, or equivalent motor-driven system— into a transverse grasping force. This force enables flexion of the finger for grasping and lifting objects. The mechanical properties of the spring blade (112) are imperative for the design of the present invention. On the one hand, the spring blade (112) must be stiff enough to provide adequate resistance when the system is flexed and to transmit sufficient force for bending. On the other hand, the entire system is designed to be soft and compliant, so when the exoskeletal finger is extended, it should not be restrictive. In other words, the spring must be stiff in one direction (to allow force transmission - e.g., in the longitudinal direction along which it is extended and retracted) and elastic in the other (to allow bending - e.g., the direction extending perpendicular to the longitudinal direction and towards the member). Embodiments of the presented invention introduce simplicity, only requiring a single spring to allow bending in a 2D plane.

[0041] In a preferred embodiment, multiple driving spring blades (112) - e.g., of multiple exoskeleton devices - are driven by a single linear motor. In a hand exoskeleton example, four driving spring blades (112) are driven by a single linear motor, particularly for heavy tasks where all fingers are manipulated the same way at the same time. In another embodiment, each driving spring blade (112) is driven by a separate driving motor. In a hand exoskeleton example, four driving spring blades (112) are driven by different motors, particularly for fine finger movements where fingers need to move relative to each other to produce an action or gesture. The thumb may also have an exoskeleton device that is driven either in unison with the other exoskeleton devices in a hand exoskeleton (e.g., using a single motor for the entire hand exoskeleton, including the four finger exoskeleton devices), or may be driven by a separate motor.

[0042] With different applications of the technology, multiple layers of springs can be added to increase output strength, range of motion, and / or control (e.g., multiple degrees of freedom).

[0043] Various additional mechanisms can be added within the rigid sections (102, 104, 106) to supplement the bending mechanism. These include but are not limited to attachment points (e.g., to connect the exoskeleton finger to a human finger as shown in photographic example of Figure 3, sensors (e.g., to measure contact forces or to serve as intention detection strategies), and varying contact surfaces (e.g., adding silicone to increase grip).

[0044] The proposed structure can be used to build a hand exoskeleton supporting finger flexion and extension motion in a natural manner. It can then serve as an assistive device to support activities of daily living and / or as a rehabilitative (therapy) device. The design of the accordion-like structure is not limited to the fingers of a hand exoskeleton. Other possible applications include providing assistance to the wrist, elbow, back, knee, ankle, or any joint of the human body. Such applications may include both rehabilitation (e.g., after traumatic or neurological injuries) or pre-rehabilitation (e.g., as a supportive structure to prevent injuries). The proposed structure may be applied as well for flexible structures in various applications, e.g. endoscopy. The proposed structure can be utilized as a soft robotic gripper for various industrial applications such as automation (e.g., a pick and place robot), or as assistive technology (e.g., prosthesis). This may be achieved using a robotic hand that is actuated using the present exoskeleton devices.

[0045] The present concept offers several advantages over existing bending mechanisms used in finger exoskeleton designs, particularly those that are tailorable but often cumbersome to assemble due to the large number of individual components required. In contrast, soft hand exoskeletons, while easier to fabricate, typically lack precise control over joint bending because of the inherent limitations in their mechanisms. The design described here strikes a balance by maintaining a soft and compliant structure while introducing an added layer of control. It enables modulation of bending properties at each joint segment. The use of 'M' segments allows the system to remain flexible yet structurally integrated, achieved through a single, 3D-printed part. This not only simplifies fabrication and assembly but also improves the interface between the exoskeleton and the human finger.

[0046] It will be appreciated that many further modifications and permutations of various aspects of the described embodiments are possible. Accordingly, the described aspects are intended to embrace all such alterations, modifications, and variations that fall within the spirit and scope of the appended claims.

[0047] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0048] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Claims

Claims1. An exoskeleton device for assisted movement of a member comprising a plurality of joints, comprising: a plurality of rigid sections including a first rigid section and a second rigid section positioned at respectively opposite ends of the member and at least one intermediate rigid section between the first and second rigid sections and positioned between neighbouring ones of said joints in the member; a repeating M structure comprising a plurality of length segments, each length segment extending between a respective pair of said rigid sections; and a driving spring blade extending at least from the first rigid section to the second rigid section, along an external region of the repeating M- structure, the driving spring blade being extendable and retractable to actuate the exoskeleton device.

2. The exoskeleton device of claim 1, comprising a said rigid section between neighbouring ones of said joints.

3. The exoskeleton device of claims 1 or 2, wherein the repeating M structure extends in a longitudinal direction over the joint and has a depth sufficient to resist bending transverse to the longitudinal direction, and a width, in the longitudinal direction, that facilitates bending.

4. The exoskeleton device of claims 1 or 2, wherein the member comprises a hand and the plurality of rigid sections comprise a rigid section between neighbouring ones of said joints.

5. The exoskeleton device of any one of claims 1 to 4, wherein the rigid sections align with bones of the member.

6. The exoskeleton device according to any one of claims 1 to 5, whereinone of the first rigid section and second rigid section is a distal rigid section with respect to the member, and the driving spring blade actuates the exoskeleton by sliding through a plurality of the rigid sections and applying a push or pull force to the distal rigid section.

7. The exoskeleton device of any one of claims 1 to 6, wherein the driving spring blade is arranged, relative to the repeating M structure, to convert a linear force into a bending movement.

8. The exoskeleton device of any one of claims 1 to 7, wherein the line of symmetry of the repeating M structure is configured to maintain constant length during actuation.

9. The exoskeleton device of any one of claims 1 to 8, wherein at least one of a density, thickness, angle, width, height and material of each M segment of the repeated M structure is selected to define a range of motion, as well as torsional and transverse stiffness during actuation.

10. The exoskeleton device of any one of claims 1 to 9, wherein the driving spring blade comprises cold-rolled stainless steel, or other flexible material.

11. The exoskeleton device of any one of claims 1 to 10, further comprising one or more attachment points to attaching the exoskeleton to the member.

12. The exoskeleton device of any one of claims 1 to 11, further comprising one or more sensors and a controller, each sensor providing a control signal to the controller for controlling extension or retraction of the drive spring blade.

13. The exoskeleton device of claim 12, wherein at least one sensor is a force sensor for providing a control signal corresponding to an intended force to be applied through the member.

14. The exoskeleton device of claim 1, wherein the member is one of an elbow, wrist, back, knee, and ankle.

15. A robotic gripper comprising an end effector and an exoskeleton device, according to any one of claims 1 to 14, attached to the end effector to assist prehension of objects or interaction with the environment.

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