Motorized upper prosthetic limb with optimized construction configuration

Abstract

Motorized upper prosthetic limb (A) comprising a hand (1) with fingers (5), a first elastically flexurally deformable element onboard each finger, wherein the first element is elastically flexurally deformable in a transverse direction (X1, X2, X3, Z1) with respect to the extension direction of each finger, a forearm (2) comprising a connection interface (4) that can be releasably attached to a user's body, and a second elastically flexurally deformable element in a transverse direction (X4, Z2) relative to the extension direction of the forearm (2), with the second elastically deformable element being interposed between the hand and the forearm to movably connect the hand to the forearm. The prosthetic limb also includes a plurality of electromechanical rotary actuators arranged on the forearm (2), and a plurality of strings, each having a first end connected to an actuator and a second end, longitudinally opposite to the first, rigidly and individually connected to one of the first or second elastically deformable elements.

Description

[0001] MOTORIZED UPPER PROSTHETIC LIMB WITH OPTIMIZED CONSTRUCTION

[0002] CONFIGURATION

[0003] DESCRIPTION

[0004] TECHNICAL FIELD

[0005] The present invention pertains to the field of robotic limbs, particularly to a motorized upper prosthetic limb comprising a plurality of electromechanical rotary actuators and a plurality of strings connected to them.

[0006] STATE OF THE ART

[0007] In the field of medical robotics, and particularly in robotic prosthetic limbs, devices have been developed and made commercially available over the years, designed to be connected, preferably in a releasable manner, to the amputated portion of a user's body. Once connected to the user's body, these devices can reproduce the movements of the missing limb, such as closing the fingers of a hand to grasp an object. However, current commercially available robotic prosthetic limbs present numerous disadvantages. For example, they are fragile, bulky, and have high production costs, making these devices economically inaccessible to much of the global population. Specifically, commercially available robotic upper prosthetic limbs have a complex construction configuration, featuring numerous mechanical components, e.g., gears, pulleys, bearings, etc., used to transmit motion between the parts of the robotic prosthetic limb to perform the desired movement by the user. However, while the presence of a large number of mechanical components allows existing solutions to have a degree of freedom comparable to that of a human limb, it also makes these solutions bulky, heavy, and unreliable, and difficult to adapt / scale according to the user's body type. Therefore, there is a longstanding need to develop simple and compact robotic upper prosthetic limbs from a construction standpoint, minimizing the number of mechanical components to reduce the overall weight of the prosthetic limb while simultaneously increasing reliability without compromising performance or limiting movements to a reduced number of degrees of freedom.

[0008] OBJECT AND SUMMARY OF THE INVENTION

[0009] The present invention aims to address at least some of the above-mentioned needs, with this goal being achieved through a motorized upper prosthetic limb, according to claim 1. According to a preferred embodiment of the present invention, a motorized upper prosthetic limb is presented, releasably attachable to an amputated or limb-deficient end of a patient, wherein the limb has a simplified construction configuration that minimizes the presence of onboard mechanical components used to actuate the movements of the limb. Advantageously, by featuring a reduced number of mechanical components, the overall weight and bulkiness of the prosthetic limb are significantly reduced, thereby enhancing its ease of maneuverability and reducing user fatigue when the prosthetic limb is connected to their body. Additionally, thanks to the simplified construction configuration, the motorized upper prosthetic limb offers significantly lower production costs compared to existing solutions, increased reliability, and reduced maintenance intervals, i.e., the reduced number of mechanical components lowers the risk of, e.g., component breakages, gear jamming, etc. Specifically, to achieve this result, the motorized upper prosthetic limb features a hand comprising fingers, each equipped with at least one first elastically flexurally deformable element in a transverse direction relative to the extension direction of each finger. For example, to replicate the movements of the fingers of a human hand, each finger of the motorized upper prosthetic limb may feature longitudinal sections, each representing a phalanx of a human finger, wherein these longitudinal sections are serially connected and rotatably mobile by means of a first elastically flexurally deformable element. Specifically, this first elastically flexurally deformable element has a construction geometry that allows it to flex in a transverse direction to the desired finger extension under the application of a load. In this way, deformation of the first elastically deformable element causes relative rotation between two longitudinal sections of the finger, reproducing a movement comparable to that of a human phalanx, e.g., a rotation towards the palm or back of the hand. Additionally, the motorized upper prosthetic limb includes a forearm with a connection interface that can be releasably attached to the user's body, e.g., shaped to adhere to the amputated or limbdeficient end and attachable to it via straps and / or belts, for example. Preferably, if the amputated or limb-deficient end is on the user's arm, the prosthetic limb may include an arm portion connected to the forearm in a rotatable manner. According to another aspect of the present invention, the prosthetic limb includes a second elastically flexurally deformable element in a transverse direction relative to the extension direction of the forearm, wherein this second elastically deformable element is interposed between the hand and the forearm to rotatably connect the hand to the forearm. In this way, through the second elastically flexurally deformable element, movements comparable to those of a human wrist can be reproduced. For example, this second elastically flexurally deformable element has a construction geometry that allows it to flex in a transverse direction to the desired extension of the finger under the application of a load, thereby rotating the hand. According to another aspect of the present invention, to actuate the movement of the fingers or hand of the motorized upper prosthetic limb, the latter includes a plurality of electromechanical rotary actuators arranged on board the forearm, e.g., fixed to a supporting structure of the forearm, and a plurality of strings, each having a first end connected to an actuator and a second end, longitudinally opposite the first, rigidly connected to one of the first or second elastically flexurally deformable elements. For example, the actuators are battery-powered and can be arranged circumferentially on the forearm, with the strings extending substantially parallel to the hand. Specifically, each finger is at least partially hollow to house the at least one first elastically deformable element and the corresponding string that connects it to a rotary actuator. According to another aspect of the present invention, the end of each string connected to one of the first or second elastically deformable elements, i.e., the one longitudinally opposite the actuator, is arranged to exert a pulling force on the same, causing a flexion of the element to which it is connected, which in turn causes a movement of the finger or hand towards the palm or back of the hand. To achieve this result without having to include mechanical transmission components on board the prosthetic limb, e.g., gears, pulleys, etc., the motorized upper prosthetic limb also includes an electronic control unit, preferably onboard the forearm, and connected in data exchange with each electromechanical actuator. Specifically, the electronic control unit is programmed to receive a signal representing a desired movement of the prosthetic limb and process the signal to actuate an actuator so that a rotation of the actuator causes a reduction in the length of the string by twisting the string itself connected to it, flexing the first or second elastically deformable element to which the string is connected towards the palm or back of the hand to perform the desired movement. For example, to perform a movement, e.g., closing / opening the fingers of the hand to grasp an object, the electronic control unit is programmed to receive a signal representing a desired movement and process the signal to selectively actuate one or more actuators to perform the movement. To do this, for example, using a widely used technique in these applications, such as electromyography (EMS), electrodes are placed on the amputated or limb-deficient end of the user's body so that the electrodes are near the user's residual muscles. These electrodes are connected in data exchange with the electronic control unit and are configured to generate electrical signals representing a muscle contraction of the residual muscles on the amputated or limb-deficient end of the body. Based on the received signal, the control unit is programmed to process the signal to actuate a corresponding actuator to perform the desired movement of the upper prosthetic limb. For example, the pulling force acting on a string, as well as the rotation speed of the electromechanical rotary actuators, can be set to be proportional to the intensity of the signal representing the user's muscle contraction.

[0010] DESCRIPTION OF THE DRAWINGS

[0011] The constructive and functional features of the motorized upper prosthetic limb can be better understood from the following detailed description, which refers to the attached figures that represent a preferred and non-limiting embodiment thereof, wherein:

[0012] Fig.l shows a view of a motorized upper prosthetic limb according to a first embodiment of the present invention;

[0013] Figs. 2 and 3 each show a view of the finger with the onboard first elastically flexurally deformable elements and the corresponding strings according to the embodiment of Fig.l;

[0014] Figs. 4a, 4b, 4c show detailed views of the first elastically flexurally deformable element;

[0015] Fig.5 shows a schematic view of the actuation of the finger movements according to the preferred embodiment of Fig.l;

[0016] Fig.6 shows a detailed view of the second elastically flexurally deformable element onboard the prosthetic limb of Fig.l;

[0017] Figs. 7a, 7b each show a detailed view of the second elastically flexurally deformable element.

[0018] DETAILED DESCRIPTION OF THE INVENTION

[0019] According to a preferred embodiment of the present invention, Fig.l shows an overall view of a motorized upper prosthetic limb A comprising a hand 1, a forearm 2 connected to the hand, and preferably, but not limited to, an arm portion 3 connected to the forearm. Specifically, depending on the area of amputation or limb deficiency of the user, the prosthetic limb may include the arm portion 3 if the user has an arm portion without a forearm, while if the user has a complete arm and a forearm portion, the motorized upper prosthetic limb may be without the arm portion 3. In both cases, the motorized upper prosthetic limb A has a connection interface 4 that can be releasably attached to the user's body so that the user can remove the prosthetic limb when desired, e.g., for resting, sleeping, etc. For example, the connection interface may have a shape made based on a 3D scan of the user's body end to which the motorized upper prosthetic limb is to be attached, e.g., a residual portion of the amputated limb.

[0020] Once applied to the user's body, the connection interface 4 can be secured in various ways, for example, by removing the air trapped in the interface area to create a vacuum, adhering the interface to the surface of the user's body. Preferably, to prevent detachment due to pressure loss in the case of vacuum attachment, additional connection elements such as straps and / or belts may be provided onboard the prosthetic limb so that they can be used in operation to keep the limb connected to the user's body, thus enhancing user safety during the use of the prosthetic limb. According to a first aspect of the present invention, and as shown in Figs. 1 and 2, the hand 1 comprises fingers 5, each equipped with at least one first elastically flexurally deformable element 6a, 6b, 6c in a transverse direction and preferably perpendicular direction to the extension direction of each finger. Specifically, this first elastically flexurally deformable element is configured to achieve movement between two portions of the finger connected to it by deforming the material from which it is made. Preferably, this first elastically deformable element is manufactured using additive printing techniques, e.g., in plastic materials characterized by a high ratio of yield stress to modulus, or ferrous materials such as spring steels.

[0021] In this way, the first elastically flexurally deformable element 6a, 6b, 6c is used to provide one or more degrees of freedom to the corresponding finger in which it is placed. As shown in Figs. 2 and 3, to replicate the movements of each finger 5 in a manner comparable to the movements of the phalanges of a human hand, each finger has a first longitudinal section Tl, e.g., representing the first phalanx of the human hand, connected to the remaining portion of the hand in a rotatable manner with respect to a first and a second rotational axis XI, Zl, transversal and preferably perpendicular to each other, wherein rotation with respect to the first axis XI causes the first longitudinal section Tl to move closer to or farther from the palm of the hand, while rotation with respect to the second axis Zl causes a finger 5 to move closer to or farther from the adjacent finger. Each finger also has a second longitudinal section T2, e.g., representing the second phalanx of the human hand, connected to the first longitudinal section Tl in a rotatable manner with respect to an axis X2, preferably parallel to the axis XI, and a third longitudinal section T3, e.g., representing the third phalanx of the human hand, connected to the second longitudinal section T2 in a rotatable manner with respect to a fourth axis X3, also preferably parallel to the axis XI.

[0022] Therefore, based on this construction configuration, each finger 5 is configured to perform rotational movements comparable to those a human hand's finger can perform. Specifically, to perform these movements, a first elastically flexurally deformable element of the first phalanx 6a is placed in a first housing Cl made longitudinally between the finger portion protruding from the palm of the hand and the first longitudinal section Tl, a first elastically flexurally deformable element of the second phalanx 6b is placed in a second housing C2 made longitudinally between the first longitudinal section Tl and the second longitudinal section T2, and a first elastically flexurally deformable element of the third phalanx 6c is placed in a third housing C3 made longitudinally between the second longitudinal section T2 and the third longitudinal section T3. Additionally, these housings Cl, C2, and C3 are longitudinally connected by openings made between one housing and the next. According to another aspect of the present invention, to enable rotational movements with respect to the aforementioned axes, each first elastically flexurally deformable element 6a, 6b, 6c has a construction configuration that promotes its deformation in one of the above-mentioned transverse directions when a load is applied to the finger.

[0023] Specifically, Figs. 4a, 4b, and 4c show detailed views of a generic first elastically flexurally deformable element placed onboard each finger, where the one in Fig. 4a is elastically deformable with respect to a first direction X2, X3, while the one in Fig. 4b is a variant of the first elastically flexurally deformable element of Fig. 4a that is elastically deformable with respect to a first direction XI but also with respect to a second direction Zl. In both figures, the first elastically flexurally deformable element has a first and a second body 7, 8, each having a first and a second base 7a, 8a, preferably flat, arranged longitudinally spaced from each other parallel to an axis Y1 so as to have base surfaces 7b, 8b facing each other. Additionally, these first and second bases 7a, 8a have a first and a second support 9, 10, respectively, extending parallel to axis Y1 from each respective base surface so as to have longitudinally opposite ends 11, 12 to said base surfaces and shaped convexly. Specifically, ends 11, 12 are in use facing each other and at least partially in contact and angularly spaced by a first angle Bl. According to another aspect of the present invention, this construction configuration allows for the relative rotational movement between the first and second bases 7 a, 8a with respect to a transverse and preferably perpendicular axis to the axis Yl, e.g., the axis X2 or the axis X3, depending on the corresponding first elastically flexurally deformable element under examination.

[0024] Specifically, the convex shape of the ends 11, 12, e.g., arched, can be used to rotate one of the first and second bodies 7, 8 or both with respect to the transverse axis so that the perimeter surface of the support of one of these bodies being rotated advances on the perimeter surface of the support of the other body. In this way, the first and second bodies become angularly closer together, defining a second angle B2 smaller than the first angle Bl. To rotate the first and second bodies 7, 8 so that they are again angularly spaced by the first angle Bl, the such first elastically flexurally deformable element has projections 13 rigidly connected cantilevered to the first and second supports 9, 10, respectively, so as to extend preferably parallel to the transverse axis, e.g., axis X2 or axis X3 of the first elastically deformable element under examination. Specifically, these projections 13 are arranged vertically spaced from each other and preferably symmetrically with respect to axis Yl to define a plurality of layers between the first and second bodies 7, 8. Preferably, each projection 13 is a flat element with surfaces facing the projection above and / or below it. Additionally, the first elastically flexurally deformable element 6b, 6c shown in Fig. 4a, i.e., the one with one degree of freedom, includes flexible connectors 14 extended longitudinally and configured to connect the first and second bodies 7, 8.

[0025] To do this, these connectors have a first end 14a rigidly connected to a portion of a projection spaced from axis X2, X3, preferably the perimeter edge, and a second end 14b, longitudinally opposite the first end, rigidly connected to a portion of another projection arranged above or below, and in which this second end 14b is positioned opposite to the first end 14a with respect to axis X2, X3. In this way, the first elastically flexurally deformable element has a construction configuration in which the flexible connectors 14 extend obliquely from the edge of one projection towards the opposite edge with respect to axis X2, X3 of the projection above and / or below. Preferably, multiple flexible connectors 14 may extend from a projection 13, for example, along the edge of the projection parallel to axis X2, X3. Additionally, these connectors are arranged to also connect a projection 13 facing the first or second body 7, 8 so that the first end 14a is rigidly connected to a portion of a projection spaced from axis X2, X3, and the second end 14b is rigidly connected to a portion of one of the base surfaces 7b, 8b to which the projection faces, so that the second end 14b is positioned opposite to the first end 14a with respect to axis X2, X3. Therefore, when the first and / or second body 7, 8 is rotated under the application of a load, the flexible connectors 14 flex, in turn, exerting an elastic reaction force that opposes the direction of the applied load, so that when the load application is interrupted, these flexible connectors 14 unload, returning the body to which the load was applied to a position such that it is again angularly spaced from the other body by the first angle Bl. The first elastically flexurally deformable element 6a shown in Fig. 4b, on the other hand, has two degrees of freedom, i.e., rotation with respect to axis XI and rotation with respect to axis Zl. To do this, this first elastically flexurally deformable element includes a third body 50 facing the second body 8 and longitudinally spaced from it. AgainAlso in this case, a third and fourth support 51, 52 extend longitudinally from the second and third bodies, with convex ends at least partially in contact, e.g., arched, so that the third and fourth bodies 51, 52 are relatively rotatable with respect to the transverse and preferably perpendicular axis Zl and preferably perpendicular to axis XI. To connect the second and third bodies 8, 50, this first elastically flexurally deformable element 6a includes additional flexible connectors 53 extended longitudinally, connecting a portion of the second body's end to a portion of the third body's end positioned opposite to axis Zl. Based on this construction configuration, when the third and / or fourth body 8, 50 is rotated under the application of a load, the flexible connectors 53 flex, in turn, exerting an elastic reaction force that opposes the direction of the applied load, so that when the load application is interrupted, these flexible connectors 53 unload, returning the body to which the load was applied to an undeformed position. For example, Fig. 4c shows the first elastically flexurally deformable element 6a in a deformed condition under the application of a first load Fl that causes rotation of the first element with respect to axis Z1 and a second load F2 that causes rotation with respect to axis XI. Therefore, by exploiting the construction geometry of the first elastically flexurally deformable element, it is possible to actuate the movement of each finger of the hand 1 of the motorized upper prosthetic limb A. To achieve this result and as shown in Figs. 2 and 3, each finger 5 features the first elastically flexurally deformable element, so that the first and second bodies 7, 8, for the elements with one degree of freedom, have their respective first and second bases 7a, 8a constrained to the walls of the respective housing C2, C3 so as to be arranged parallel to the extension of the finger, while the elements with two degrees of freedom have the first and third bodies 8, 50 constrained at the ends to the walls of the housing Cl. In this way, by rotating one of the first, second, or third bodies 7, 8, 50 or both of each elastically flexurally deformable element 6a, 6b, 6c, it is possible to selectively rotate the parts of the finger with respect to the desired rotational axis. According to another aspect of the present invention, to actuate the rotation of at least one part of each finger 5, it is necessary to deform the first elastically flexurally deformable element in a transverse direction relative to the extension direction of each finger. As shown in the schematic view in Fig.l, to achieve this result, the motorized upper prosthetic limb A comprises a plurality of strings and a plurality of electromechanical rotary actuators arranged on the forearm 2, e.g., circumferentially fixed to a supporting structure of the forearm (not shown in the figure). Specifically, each string has a first end connected to an actuator and a second end, longitudinally opposite to the first end, rigidly connected to a first elastically deformable element. Additionally, to connect a string to an actuator on one side and to a first elastically flexurally deformable element 6a, 6b, 6c on the other, each string extends from the respective actuator parallel to the extension of the forearm 2 and at least partially along the palm of the hand 1 to reach the finger that carries the respective first elastically flexurally deformable element to which each string is connected. Furthermore, the motorized upper prosthetic limb A comprises a string spacer 40 rigidly connected to the supporting structure of the forearm and extending from the end of the forearm towards the hand longitudinally along at least a section of the forearm towards the actuators. Specifically, this string spacer 40 has a plurality of longitudinal grooves 40a made circumferentially and substantially parallel to the extension of the forearm, with these grooves configured to guide each string longitudinally towards the hand 1. In this way, it is also possible to prevent a string from coming into contact with adjacent ones, as the forearm has a longitudinal profile preferably converging towards the hand, and such to causecausing a reduction in the radial distance between the strings as they approach the wrist compared to the radial distance between the strings at the end connected to the respective actuator. Additionally, according to a preferred variant shown in Fig. 6, the string spacer 40 comprises a plurality of shuttles 41, each at least partially engaged within each groove so as to be translatable along the respective groove in which it is engaged. Furthermore, each shuttle 41 features onboard anchors 42, preferably pairs of anchors, arranged in series parallel to the longitudinal extension of the groove. Moreover, these anchors extend radially from each shuttle, with longitudinally opposite ends to those fixed to the shuttle extending at least partially cantilevered parallel to the groove relative to the remaining portion of the anchor. Advantageously, each anchor is used to avoid the need for a single string to connect an actuator to a first deformable element onboard the finger, thereby reducing assembly complexity and increasing reliability and ease of maintenance of the prosthetic limb. Specifically, to connect an actuator to a first deformable element onboard the finger, an arm string 17a is provided, with one end connected to an actuator and the longitudinally opposite end connected to a first anchor 42a, and a hand string 17b, with one end connected to a second anchor 42b arranged on the shuttle 41 along with the first anchor, and the longitudinally opposite end connected to a first elastically flexurally deformable element 6a, 6b, 6c. For example, to secure the respective ends of the arm and hand strings 17a, 17b to a respective anchor 42a, 42b, each string has looped ends to be releasably engaged with a pair of anchors onboard a shuttle. To do this, the anchors are elastically flexible to be flexed longitudinally to be looped by the looped end of the string, so that when they are released from a flexed position to an undeformed one with the looped ends engaged on them, the longitudinal distance between the cantilevered ends of each pair of anchors increases, thereby generating a tension on the looped string end that counteracts any radial movement of the looped string end to escape from the anchors, where such a radial movement is, in any case, blocked by the presence of the cantilevered ends of the anchors that prevent the extraction of the looped end from the anchors.

[0026] As shown in the schematic view of Fig.5, to actuate the movement of each finger 5, the motorized upper prosthetic limb A features a first group of strings and actuators Gl, comprising a first and second actuator 16a, 16b, and a first and second string 15a, 15b configured to actuate a movement representative of the movement of the first phalanx of a human hand. Specifically, each of these second strings has the first end connected to the first and second actuator, respectively, with these first and second strings extending along a section of the first housing Cl from the palm side of the hand 1, i.e., under the first elastically deformable element of the first phalanx 6a. Specifically, these first and second strings have their second ends rigidly fixed to the finger on the tip side of the finger relative to the first elastically deformable element of the first phalanx 6a, e.g., fixed to a first locking element 19 preferably arranged in a fourth housing C4 made longitudinally between the first and second housing Cl, C2. Furthermore, the second ends of the strings 15a, 15b are rigidly fixed to the finger in a longitudinally opposite position relative to the second axis Zl. Additionally, this first group of hand strings and actuators includes a third actuator 16c and a third string 15c configured to actuate a movement representative of the movement of the second phalanx of a human hand.

[0027] Specifically, the third string 15c has the first end connected to the third actuator 16c, with this third string extending along the first housing Cl on the longitudinally opposite side to the first and second strings 15a, 15b with respect to the first elastically deformable element of the first phalanx 6a, i.e., on the back of the hand, and at least partially along the second housing C2 on the palm side of the hand, i.e., under the first elastically deformable element of the second phalanx 6b, passing through the fourth housing C4. Again, the third string 15c is rigidly fixed to the finger, e.g., to a second locking element 20 preferably arranged at least partially within a fifth housing C5 made longitudinally between the second and third housing C2, C3. Moreover, this first group of hand strings and actuators G1 includes a fourth actuator 16d and a fourth string 15d configured to actuate a movement representative of the movement of the third phalanx of a human hand. Specifically, the fourth string 15d has the first end connected to the fourth actuator 16d and extends along the finger on the back of the hand to the third longitudinal section T3, i.e., placed above the first elastically deformable elements of the first, second, and third phalanges 6a, 6b, 6c. Furthermore, the second end of this fourth string 15d is rigidly fixed to the finger, e.g., in a seat 21 made in a portion of the third longitudinal section T3. Therefore, to perform a desired movement of a finger 5 according to the construction configuration described above, the motorized upper prosthetic limb A further includes an electronic control unit onboard the forearm 2 and connected in data exchange with each electromechanical actuator of the fingers. Specifically, this electronic control unit is programmed to receive a signal representing a desired movement of the prosthetic limb and process the signal to actuate an actuator so that a rotation of the actuator causes a reduction in the length of the string by twisting the string itself connected to it. Specifically, since the second end of each string is fixed to a portion of the finger, when an actuator is actuated, not only is the length of the string reduced, but a pulling force is also generated that acts on this portion of the finger. Specifically, the generation of a pulling force on the end of a string is transmitted to the first elastically deformable element to which the string is connected. Therefore, as the point of application of this pulling force is longitudinally shifted with respect to the point of contact between the first and second body 7, 8 or between the first and third body 50 of the first elastically flexurally deformable element to which the string is connected, i.e., shifted towards the fingertip, an angular moment is generated that causes a deformation of this first elastically flexurally deformable element towards the palm or back of the hand to perform the desired movement.

[0028] Specifically, the actuation of the first and second actuators 16a, 16b in a concordant rotational direction causes flexion of the first elastically flexurally deformable element of the first phalanx 6a towards the palm or back of the hand 1, i.e., a rotation of the first longitudinal section T1 with respect to the first axis XI, while the actuation of the first and second actuators 16a, 16b in a discordant rotational direction causes flexion of the first elastically flexurally deformable element of the first phalanx 6a towards the adjacent fingers, i.e., a rotation of the first longitudinal section T1 with respect to the second axis Zl.

[0029] Similarly, the actuation of the third actuator 16c causes flexion of the first elastically flexurally deformable element of the second phalanx 6b towards the palm or back of the hand 1, i.e., a rotation of the first longitudinal section T1 with respect to the third axis X2, while the actuation of the fourth actuator 16d causes flexion of the first elastically flexurally deformable element of the third phalanx 6c towards the back of the hand 1. Advantageously, when an actuator is actuated, the corresponding string generates a pulling force on the anchors so that the shuttle is actuated to translate towards the actuators, thus advancing the other string that connects the hand to an anchor to actuate the deformation of the first elastically flexurally deformable element towards the palm or back of the hand 1. Moreover, each first elastically deformable element 6a, 6b, 6c stores elastic energy when the string to which it is connected shortens due to the actuation of a corresponding rotary actuator, causing deformation of the element. However, when actuator actuation is interrupted, the elastic energy stored by the first elastically flexurally deformable element is released, favoring the return of the element to an undeformed position. Specifically, due to the resistant torque exerted by the rotary actuator when it is not actuated, the elastic energy stored by the first elastically flexurally deformable element may not be sufficient, so the actuator can be reactuated by rotating in the opposite direction to help the first elastically flexurally deformable element return to an undeformed condition, i.e., to extend the finger again. Therefore, as can be understood, the energy required by a rotary actuator is greater when the finger needs to be closed than when it is reopened, as the first elastically flexurally deformable element exerts an elastic reaction force that opposes the pulling force of the string.

[0030] Preferably, each finger 5 includes a support string 15e with one end rigidly connected to the finger, e.g., to a third locking element 22 preferably arranged in the fourth housing C4 and a second end, longitudinally opposite the first, rigidly fixed to a portion of the third longitudinal section T3. Specifically, this support string extends from the third locking element 22 towards the fingertip, positioned above the first elastically deformable element of the second phalanx 6b, and passing through the fifth housing C5, it is deflected to be positioned longitudinally under the first elastically deformable element of the third phalanx 6c, i.e., on the palm side of the hand. The arrangement of the support string 15e is exploited so that when the third actuator 16c is actuated to rotate the second longitudinal section T2, i.e., to replicate the movement of the second phalanx of the human hand, a pulling force is exerted on the first elastically deformable element of the second phalanx 6b such that its deformation generates a further pulling force on the support string 15e, which in turn rotates the third longitudinal section T3 towards the palm of the hand without the need for an actuator to which the support string must be connected. Therefore, as can be understood from the schematic view in Fig.5, each finger preferably has four degrees of freedom actuated by five strings, four of which are actuated by a corresponding actuator.

[0031] According to another aspect of the present invention, the hand 1 is connected to the forearm 2 in a rotatable manner to perform movements comparable to those executed by the wrist of a human limb. Specifically, Fig. 7 shows a view of a second elastically flexurally deformable element 23 interposed between the forearm 2 and the hand 1 to rotatably connect the latter to the forearm and in a transverse direction relative to the extension direction of the forearm. Specifically, this second elastically flexurally deformable element 23 is configured to replicate movements comparable to those of a human wrist, e.g., making the hand 1 rotatable with respect to a fifth and sixth axis X4, Z2, transverse and preferably perpendicular to each other. For example, rotation of the hand 1 with respect to the fifth axis X4 causes a movement of the hand towards the wrist or back, while rotation with respect to the sixth axis Z2 causes a lateral movement of the hand.

[0032] To achieve this result, as shown in Fig.6, the motorized upper prosthetic limb A includes a second group of actuators and strings G2 [, comprising a fifth, sixth, seventh, and eighth actuator 24, 25, 26, 27 arranged on the forearm 2, i.e., fixed to the supporting structure together with the first group of actuators G1 of the hand 1, to which a respective fifth, sixth, seventh, and eighth string 28, 29, 30, 31 is connected. These strings are arranged to have a first end connected to a respective actuator extending substantially parallel to the extension of the arm and preferably passing each string through the string spacer 40 to avoid contact with adjacent ones. Furthermore, these strings have a second end longitudinally opposite the first end, connected to the second elastically flexurally deformable element 23. Specifically, the second elastically flexurally deformable element 23 has a construction configuration comparable to that of the first elastically flexurally deformable element 6a of the first phalanx, with parts common to the first elastically deformable element 6a retaining the same numbering with an added 100. Specifically, to actuate the wrist movements along the above- mentioned axes, the fifth and sixth strings 28, 29 extend from their respective actuator towards the hand in a longitudinally opposite manner to the second elastically flexurally deformable element 23 and are arranged so that one end is longitudinally opposite to that constrained to the actuator, positioned one on the palm side and one on the back of the hand 1. In this way, when an actuator of the fifth or sixth string 28, 29 is actuated, a force is exerted on the end of the string on the hand, generating an angular moment that, in turn, causes a deformation of the second elastically deformable element relative to axis X4. Therefore, a flexion or extension movement comparable to that of the human wrist can be performed. Additionally, the seventh and eighth strings 30, 31 extend from their respective actuator towards the hand in a longitudinally opposite manner to the second elastically flexurally deformable element 23 and are arranged so that one end is longitudinally opposite to that constrained to the actuator, positioned laterally, one on the thumb side and the other on the pinky side of the hand 1. In this way, when an actuator of the seventh or eighth string 30, 31 is actuated, a force is exerted on the end of the string on the hand, generating an angular moment that, in turn, causes a deformation of the second elastically deformable element relative to axis Z2.

[0033] Therefore, as described for the first group of finger actuators and strings Gl, each electromechanical actuator of the wrist is connected in data exchange to the electronic control unit. Again, this electronic control unit is programmed to receive a signal representing a desired movement of the hand 1 and process the signal to actuate an actuator so that a rotation of the actuator causes a reduction in the length of the string by twisting the string itself connected to it. Specifically, since the second end of each string is connected to the second elastically flexurally deformable element 23, when an actuator is actuated, not only is the length of the string reduced, but a pulling force is also generated that acts on this second deformable element.

[0034] Preferably, as described for the first group of hand strings and actuators Gl, the construction configuration with shuttles 41 and anchors onboard the string spacer 40 can be used to avoid the need for a single string to connect an actuator to a first deformable element onboard the finger, thereby reducing assembly complexity and increasing reliability and ease of maintenance of the prosthetic limb. In this way, when an actuator is actuated, the corresponding string generates a pulling force on the anchors so that the shuttle is actuated to translate towards the actuators, thus advancing the other string that connects the hand to an anchor to actuate the deformation of the second elastically flexurally deformable element. Fig. 7b shows a deformed condition of the second elastically flexurally deformable element under the application of loads that cause rotation relative to the fourth and fifth axis X4, Z2.

[0035] Preferably, if the motorized upper prosthetic limb A includes an arm portion 3, an additional actuator 32 may be provided onboard the forearm 2, connected to a string 33 extending from the actuator towards the arm portion to make the forearm rotatable relative to the arm portion 3, i.e., to replicate a movement comparable to the elbow movement of a human limb. To achieve this result, the prosthetic limb includes a third elastically flexurally deformable element relative to a seventh axis X5, and having a construction configuration comparable to the first or second elastically deformable element, but with larger dimensions to connect the arm to the forearm and support the weight of the latter. Specifically, to actuate the arm movement relative to axis X5, a string is provided, constrained at one end to a rotary actuator onboard the arm 3, and constrained at the longitudinally opposite end to a portion of forearm 2. In this way, when the rotary actuator is actuated, the string shortens, generating a pulling force on the forearm, which in turn rotates relative to axis X5. To extend the forearm again, it is sufficient to interrupt the actuation of the actuator so that the arm extends due to gravity.

[0036] To protect the various components described above and at the same time to cover the motorized upper prosthetic limb A, a covering made of a material with rigidity characteristics similar to human skin may be provided, so that this covering wraps around each finger 5 and the remaining portion of the hand, as well as the forearm 2 and the arm portion 3 if present. Preferably, this covering may include onboard sensors connected in data exchange with the electronic control unit so that the intensity and direction of contact forces between the soft covering and the objects being grasped (possibly also the distribution of these forces, i.e., the pressure profile) can be measured in real-time.

[0037] To power the electromechanical rotary actuators, the motorized upper prosthetic limb A includes batteries preferably housed inside the arm 3, if present, so that each is electrically connected to an actuator. Preferably, to reduce the overall weight of the prosthetic limb A, the electronic control unit and the batteries 32 may be placed outside the forearm 2, e.g., inside a portable container such as a backpack, and configured to be electrically connected to the actuators onboard the forearm 2.

[0038] Additionally, to perform a movement, e.g., closing / opening the fingers of the hand 1 to grasp an object or moving the hand itself to keep an object vertical, the electronic control unit is programmed to receive at least one signal representing a desired movement and to process the signal to generate a control signal to selectively actuate one or more actuators to perform the movement. To do this, for example, a widely used technique in this type of application, such as electromyography (EMS), can be used, where electrodes (not shown in the figure) can be placed on the amputated or limb-deficient end of the body so that these electrodes are close to the user's residual muscles. Specifically, these electrodes are connected in data exchange with the electronic control unit and are configured to generate electrical signals representing a muscle contraction of the residual muscles on the amputated or limbdeficient end of the body. Based on the received signal, the control unit is then programmed to process the signal to generate the control signal to actuate a corresponding actuator and perform the desired movement of the upper prosthetic limb.

[0039] For example, the pulling force acting on a string, as well as the rotation speed of the electromechanical rotary actuators, can be set to be proportional to the intensity of the signal representing the user's muscle contraction. Alternatively, actuator actuation to perform a desired movement can be based on using neural signals from the user's brain or nerves as input to the control unit.

[0040] Preferably, each finger 5 of the hand can be manufactured as a single piece, e.g., using additive manufacturing processes. Alternatively, each component can be produced individually, e.g., using additive manufacturing processes, and then assembled with minimal use of connecting elements to avoid increasing the overall weight of the prosthetic limb, e.g., assembling the components by interference. Preferably, the first and second elastically flexurally deformable elements are made using materials that maximize the ratio of Young's modulus to yield stress. For example, plastic materials such as Nylon can be used for the first and second elastically deformable elements, while TPU can be used for the prosthetic limb covering, or Nylon can be used for both components.

Claims

CLAIMS1. Motorized upper prosthetic limb (A) comprising:— a hand (1) comprising fingers (5)— a first elastically flexurally deformable element (6a, 6b, 6c) onboard each finger, wherein said first element is elastically flexurally deformable in a transverse direction (XI, X2, X3, Zl) with respect to the extension direction of each finger— a forearm (2) comprising a connection interface (4) releasably attachable to a user's body— a second flexurally elastically deformable element (23) in a transverse direction (X4, Z2) with respect to the direction of extension of the forearm (2), such a second elastically deformable element being placed between the hand and the forearm so as to movably connect to rotation the hand to the forearm— a plurality of electromechanical rotary actuators (16a, 16b, 16c, 16d) arranged onboard the forearm (2)— a plurality of strings each having a first end connected to one of said actuators and a second end, longitudinally opposite to the first end, rigidly and individually connected to one of the first and second elastically deformable element; wherein when an actuator (16a, 16b, 16c, 16d) is actuated, the rotation of such an actuator causes a reduction in the length of the string by twisting the string itself connected thereon by bending the first or second elastically deformable element (6a, 6b , 6c; 23) to which such a string is connected towards the palm or back of the hand (1) to perform a desired movement.

2. Prosthetic limb (A) according to claim 1, wherein each finger (5) comprises a first, a second and a third longitudinal section (Tl, T2, T3), wherein the first longitudinal section (Tl) is movably connected to rotation to the remaining portion of the hand (1) with respect to a first and a second axis (XI, Zl) transversal to each other through a firstelastically deformable element (6a) of the first phalanx, the second longitudinal section (T2) is movably connected to rotation to the first section (Tl) with respect to a third axis (X2) through a first elastically deformable element (6b) of the second phalanx, and the third longitudinal section (T3) is movably connected to rotation to the second section (T2) with respect to a fourth axis (X3) through a first elastically deformable element (6c) of the third phalanx.

3. Prosthetic limb (A) according to claim 2, comprising a first group of actuators and strings (Gl) between said plurality of actuators and said plurality of strings, comprising a first and a second string (15a, 15b) and a first and a second actuator (16a, fob) to which such strings are connected respectively, and such strings extending at least partly along each finger (5) from the side of the palm of the hand (1) in a manner opposite to a longitudinal axis of the finger, and said first and second strings (15a, 15b) being rigidly connected to one end of the first elastically deformable element of the first phalanx (6a) on the side of the tip of the finger, so that a rotation in the same direction of said first and second actuators (16a, fob) causes a rotation of the first longitudinal section (Tl) with respect to the first axis (XI), while a rotation in opposite directions of such actuators causes a rotation of such a first longitudinal section with respect to the second axis (Zl) towards the finger next to.

4. Prosthetic limb (A) according to claims 2 and 3, wherein the first group of actuators and strings (Gl) comprises a third string (15c) and a third actuator (16c) to which such a string is connected, and extending such a string at least partly along each finger (5) from the back of the hand (1) in a manner opposite to the first and second string with respect to the first elastically flexurally deformable element of the first phalanx (6a), and further extending such a third string towards the tip of the finger deviating from the side of the palm of the hand (1) so as to be rigidly connected to one end of the first elasticallydeformable element of the second phalanx (6b) from the side of the tip of the finger so that a rotation of the third actuator (15c) causes a rotation of the second longitudinal section (T2) with respect to the third axis (X2).

5. Prosthetic limb (A) according to claims 2 to 4, wherein the first group of actuators (16) and strings (15) comprises a fourth string (15d) and a fourth actuator (15d) to which such a string is connected, and extending such a string along each finger (5) on the side of the back of the hand (1) so as to be rigidly connected to the first elastically deformable element of the third phalanx (6c) on the side of the tip of the finger so that a rotation of the fourth actuator causes a rotation of the third longitudinal section (T3) with respect to the fourth axis (X3) .

6. Prosthetic limb (A) according to claims 2 to 5, comprising a support string (15e) having a first end rigidly connected to the end of the first flexurally elastically deformable element of the second phalanx (6b) on the forearm side (2 ), and extending such a support string from the side of the back of the hand (1) deviating from the side of the palm of the hand so as to have a second end longitudinally opposite to the first end, rigidly connected to the first elastically deformable element of the third phalanx (6c) to the side of the fingertip; wherein when the third string (15c) apply a pulling force on the first elastically deformable element of the second phalanx (6b) so as to implement the rotation of the second longitudinal section (T2) towards the palm of the hand (1), the deformation of such a first deformable element (6b) generates a further pulling force on the support string (15e) so as to rotate the third longitudinal section (T3) towards the palm of the hand.

7. Prosthetic limb (A) according to any of the preceding claims, wherein the first elastically deformable element (6a, 6b, 6c) comprises a first and a second body (7, 8) having respectively a first and a second base between them facing each other, and a first and asecond support (9, 10) which extend longitudinally respectively from said first and second base so as to have convex ends (11, 12) facing and at least partly in contact, and further comprising said first and second body projections (13) and flexible connecting elements (14), wherein such projections are longitudinally interposed and spaced between the first and second base, extending transversally cantilevered from the supports (9, 10), and the flexible connecting elements (14) presenting a first end rigidly connected to a first projection and a second end longitudinally opposite to the first end, rigidly connected to a second projection facing the first support in an opposite manner with respect to a transversal axis (XI, X2, X3) to the extension direction of the supports, and the first and second body (7, 8) being movable between a first position wherein such first and second body are angularly spaced apart by a first angle (Bl) and the flexible connecting elements (14) are unloaded, and a second position wherein such first and second body are rotated with respect to the axis (XI, X2, X3) so as to be angularly spaced apart by a second angle (B2) lower than the first angle (Bl) and the flexible connecting elements are loaded so as to generate an elastic reaction force to bring such first and second body back to the first position.

8. Prosthetic limb (A) according to any of the preceding claims, comprising a second group of actuators and strings (G2) between said plurality of actuators and said plurality of strings, comprising a fifth, sixth, seventh and eighth string (28 , 29, 30, 31) and a fifth, sixth, seventh and eighth actuator (24, 25, 26, 27) to which respectively such strings are connected, and such strings extending in a manner substantially parallel to the extension of the forearm towards the hand (1) so that the fifth and sixth strings are connected to the second elastically flexurally deformable element (23) so as to have an end longitudinally opposite to that constrained to the actuator arranged one on the palm side and one end on the back side of the hand (1), and the seventh and eighth so as to havean end longitudinally opposite to that constrained to the actuator, arranged laterally, one on the thumb side and the other on the little finger side of the hand; and, when implemented, the fifth and sixth strings generate a first torque to deform the second flexurally elastically deformable element with respect to an axis (X4), and the seventh and eighth strings generate a second torque to deform the second elastically deformable element bending with respect to the axis (Z2).

9. Actuation method of a motorized upper prosthetic limb (A) comprising the steps of:— Providing a prosthetic limb in accordance with one or more of the preceding claims 1 to 10:— Providing at least one sensor for detecting a signal representative of a desired movement of said limb, said at least one sensor being preferably of the type for detecting electromyographic or neural signals that can be positioned on the end of the user's body without a human limb— Providing an electronic control unit connected or connectable in data exchange with such plurality of sensors and with each electromechanical rotary actuator, wherein such an electronic control unit is programmed to:— receiving a signal representative of a desired movement of the prosthetic limb (A) from the plurality of sensors arranged on the extremity of the user's body— processing this signal to actuate an actuator so that a rotation of this actuator causes a reduction in the length of the string by twisting the string itself connected to it by bending the first or second elastically deformable element (6a, 6b, 6c; 23) to which this string is connected towards the palm or back of the hand (1) to perform the desired movement.

10. Kit for the artificial reproduction of the functional capabilities of an upper limb of a human body comprising:— A prosthetic limb according to one or more of the preceding device claims;— A control unit comprising at least one electronic control unit configured to run a software whose instructions implement the steps of the method claims;— At least one sensor for detecting a signal representative of a desired movement of said limb, said at least one sensor being preferably of the type for detecting electromyographic or neural signals.

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