Underactuated artificial hand
The underactuated robotic hand with a main cable system and pulley system addresses limitations of existing underactuated hands by enabling varied finger movements and grasps, improving compactness, ease of command, and reducing complexity and cost for medical and industrial applications.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- FOND INST ITAL DI TECH
- Filing Date
- 2026-01-21
- Publication Date
- 2026-07-30
AI Technical Summary
Existing underactuated artificial hands have limited poses and grasps, are difficult to command, and are complex to construct, making them inadequate for medical and industrial applications, especially in prosthetic use where command variability is reduced.
An underactuated robotic hand with a reduced number of actuators, featuring a main cable system and multiple fingers with independent motion control, allowing for varied finger movements and grasps through a combination of actuators and pulley systems to manage tension and motion independently.
The hand achieves a higher number of poses and grasps, meets compactness and ease of command requirements, and reduces construction complexity and cost, enhancing its suitability for medical and industrial use.
Smart Images
Figure IB2026050538_30072026_PF_FP_ABST
Abstract
Description
[0001] DESCRIPTION
[0002] IMPROVED ARTIFICIAL HAND
[0003] The present invention relates to an artificial hand of the type specified in the preamble of the first claim.
[0004] In particular, the object of the present invention is a underactuated robotic hand, that is, configured to perform grasping and / or manipulation of objects with a number of actuators lower than that of the degrees of freedom and capable of reproducing the movements of a human hand. More specifically, the hand is an artificial hand for industrial use (for example usable as an anthropomorphic end effector of a robotic arm) and especially a hand for medical use, that is, a hand usable in the medical field (for example, for performing rehabilitation and / or for prosthetic use) hereinafter simply referred to as medical hand or medical artificial hand.
[0005] As known, artificial hands and, more precisely, medical hands are divided into two main classes: passive and active.
[0006] Passive hands are aimed at reconstructing a mutilated body segment in order to restore bodily integrity with particular attention to the aesthetic aspect. These hands are characterised by a rigid structure with non-motorised phalanges. They are not capable of performing grasps. Active hands, on the other hand, comprise mechanical and / or electronic components which, articulating the parts forming the hand with one another, are capable of reproducing various poses and therefore different grasps.
[0007] Active artificial hands are in turn divided into two groups.
[0008] The first group is characterised by a number of actuators equal to that of the degrees of freedom and a control unit that independently commands the actuators with respect to one another so that the hand is capable of assuming any pose / grasp.
[0009] While an almost infinite number of poses can be achieved, these artificial hands require an input which, having to define each degree of freedom, is extremely rich in information and particularly difficult to manage.
[0010] It is emphasised how this drawback is evident in the case of medical hands where the command of the hand may be given by contractions of the residual arm muscles and therefore with an extremely reduced number of commands.
[0011] Furthermore, due to the high number of actuators, these artificial hands have large dimensionsand complexity both in construction and in programming.
[0012] Therefore, in underactuated artificial hands the number of actuators is lower than the number of degrees of freedom.
[0013] An example of underactuated artificial hand provides for the use of one actuator for each finger connected to the individual phalanges so as to command their rotation. The fingers are thus movable independently of one another.
[0014] In some cases, the underactuated artificial hand may provide for a single actuator which, connected to the various phalanges, allows them to be commanded in simultaneous flexion. Examples of underactuated robotic hands are described in patent documents WO2017077429, EP1195151 A1 , W02007076763A2, WO2014111843A2, WO2013185231 A1 , US2014097631 A1 , US4884761A, EP0045818A1 and WO2017199127.
[0015] The known technique described comprises some important drawbacks.
[0016] In particular, known underactuated artificial hands define only a limited number of poses and, above all, are almost incapable of correctly manipulating an object being grasped. In particular, these underactuated artificial hands are not capable of varying the speed of mutual rotation between the phalanges / fingers connected to a single actuator.
[0017] This aspect is evident in the case of underactuated prosthetic hands where the variability of the commands given as input is extremely reduced.
[0018] It is emphasised that, consequently, the above-mentioned drawback is also evident in all artificial hands with a number of actuators lower than that of the degrees of freedom. In fact, even by increasing the number of actuators, underactuated artificial hands will always have degrees of freedom which, being connected to a single actuator, have an invariable ratio between speeds. Another important drawback is therefore represented by the limited number of poses and, consequently, of grasps obtainable with an underactuated artificial hand.
[0019] For example, the invariability of the ratio between the speeds of the degrees of freedom makes it almost impossible to vary the order in which the fingers close forming a fist or assuming a pose or grasp.
[0020] It is noted how such drawbacks are accentuated by the fact that a robotic hand must meet requirements of compactness, realistic movement and ease of command which, to date, prove to be mutually incompatible. This situation is especially evident in the medical field where, infact, the above-mentioned drawbacks make a known underactuated prosthetic hand hardly adequate to meet the patient’s expectations.
[0021] Finally, a non-secondary drawback is represented by the constructional complexity and difficulty of an artificial hand and therefore by its high implementation costs.
[0022] In this situation, the technical task underlying the present invention is to devise an artificial hand capable of substantially overcoming the drawbacks mentioned.
[0023] Within the scope of said technical task, an important object of the invention is to have an artificial hand capable of defining an increased number of poses and thus comparable to those of a human hand.
[0024] In particular, an important object of the invention is to implement an artificial hand that allows the user to vary the movement of the various fingers and thus to modify the pose / grasp of the hand itself.
[0025] Another object of the invention is to develop an artificial hand capable of better meeting the requirements of compactness, realistic movement and ease of command.
[0026] A further important object of the invention is to obtain an artificial hand that has low constructional complexity and difficulty and therefore relatively low implementation costs.
[0027] The technical task and the objects specified are achieved by an artificial hand as claimed in the annexed claim 1. Examples of preferred embodiments are described in the dependent claims. The features and advantages of the invention are clarified below by the detailed description of preferred embodiments of the invention, with reference to the accompanying drawings, in which:
[0028] Figure 1 shows, to scale, a perspective view of the artificial hand according to the invention;
[0029] Figure 2 is a top view, to scale, of the artificial hand according to the invention;
[0030] Figure 3 illustrates, to scale, an assembly of the artificial hand of Figure 1 ;
[0031] Figure 4 shows, to scale, a gripping configuration of the artificial hand according to the invention;
[0032] Figure 5 displays, to scale, another gripping configuration of the hand; and
[0033] Figure 6 presents, to scale, a further gripping configuration of the artificial hand according to the invention.
[0034] In the present document, dimensions, values, shapes and geometric references (such as perpendicularity and parallelism), when associated with words such as "approximately" or othersimilar terms such as "almost" or "substantially", are to be understood as subject to measurement errors or inaccuracies due to production and / or manufacturing errors and, above all, to a slight deviation from the value, dimension, shape or geometric reference with which they are associated. For example, if associated with a value, such terms preferably indicate a divergence of no more than 10% of the value itself.
[0035] Moreover, when used, terms such as “first”, “second”, “upper”, “lower”, “main” and “secondary” do not necessarily identify an order, a priority of relationship or relative position, but may simply be used to more clearly distinguish between different components.
[0036] Unless otherwise indicated, “perpendicular”, “transverse”, “parallel”, or “normal”, or other terms of geometric positioning between geometric elements (e.g., axes, directions, and straight lines) are to be understood with reference to their mutual geometric position between corresponding projections. Said projections are defined on a single plane parallel to the lying plane(s) of said geometric elements.
[0037] The measurements and data reported herein are to be considered, unless otherwise indicated, as carried out in the ICAO Standard Atmosphere (ISO 2533:1975).
[0038] Unless otherwise specified, as appears from the following discussions, it is considered that terms such as “processing”, “computing”, “determining”, “calculating”, or the like, refer to the action and / or processes of a computer or similar electronic computing device that manipulates and / or transforms data represented as physical quantities, such as electronic magnitudes of registers of a computer system and / or memories, into other data similarly represented as physical quantities within computer systems, registers, or other storage, transmission or information display devices.
[0039] With reference to the Figures, the artificial hand according to the invention is globally indicated by the number 1.
[0040] It is identifiable, as better described below, in an underactuated robotic hand, that is, having a reduced number of actuators, in particular lower than that of the degrees of freedom, and capable of reproducing the movements of an anthropomorphic hand suitably having at least three fingers. In particular, the artificial hand 1 is for industrial use (for example as an anthropomorphic end effector of a robotic arm) or for medical use and, therefore, identifiable as a rehabilitative, prosthetic or myoelectric hand.
[0041] The artificial hand 1 comprises a base body 2 identifiable in the palm of the hand 1 .The base body 2 is adapted to be constrained to an external element such as a robotic arm, for example in the case of artificial hand 1 for industrial use, or a human limb, for example in the case of artificial hand 1 for medical use.
[0042] The base body 2 defines a prevailing extension surface 2a preferably flat.
[0043] The prevailing extension surface 2a may be barycentric to the body 2.
[0044] The artificial hand 1 comprises at least one finger 3 hinged to the base body 2 and, precisely, a plurality of fingers 3 each of which, appropriately individually, hinged to the base body 2.
[0045] Precisely, the artificial hand 1 comprises a main finger 3a hinged to the base body 2 and at least one auxiliary finger hinged to the base body 2 and configured to cooperate with the main finger 3a for example, for the grasping of an object.
[0046] In detail, the artificial hand 1 comprises a pair of auxiliary fingers comprising, in turn, a first auxiliary finger 3b hinged to the base body 2 and a second auxiliary finger 3b also hinged to the base body 2.
[0047] Preferably, the hand 1 also comprises at least one additional finger hinged to the base body 2 and configured to cooperate with the main finger 3a and the at least one auxiliary finger 3.
[0048] In particular, it comprises a pair of additional fingers comprising a first additional finger 3d hinged to the base body 2 and a second additional finger 3e also hinged to the base body 2.
[0049] More preferably, in the case of an anthropomorphic artificial hand 1, the artificial hand 1 comprises a pair of auxiliary fingers 3b and 3b and a pair of additional fingers 3d and 3e; wherein the main finger 3a is identifiable as the thumb, a first additional finger 3d hinged to the base body 2 is identifiable as the index finger and a second additional finger 3d is identifiable as the middle finger, the first auxiliary finger 3b is identifiable as the ring finger and the second auxiliary finger 3b is identifiable as the little finger.
[0050] The main finger 3a is adapted to work in opposition to one or more auxiliary fingers 3b and 3c. Alternatively or additionally, the main finger 3a is adapted to work in opposition to one or more additional fingers 3d and 3e.
[0051] Each finger 3 comprises a proximal phalanx 31 to the base body 2 and suitably a distal phalanx 32 from the base body.
[0052] The proximal phalanx 31 is hinged to the base body 2 defining a first axis of rotation 31a.
[0053] The first axis 31a may be substantially parallel to the prevailing surface 2a.The distal phalanx 32 is hinged to the proximal phalanx 31 on the side opposite the base body 2 defining a second axis of rotation 32a.
[0054] Preferably, the axes 31a and 32a of the phalanges of the same finger are substantially parallel to one another.
[0055] Optionally, at least one among one or more fingers 3 may comprise at least one intermediate phalanx 33 interposed and hinged between proximal phalanx 31 and distal phalanx 32 so as to rotate with respect to said phalanges around a third axis of rotation 33a suitably parallel to axes 32a and / or 31 a of the respective finger.
[0056] Phalanges 31 , 32 and 33 are known per se to the person skilled in the art and are therefore not further described.
[0057] Each finger 3 may also comprise a connection phalanx 34 for fastening the finger 3 (in particular the proximal phalanx 31) to a base body 2; such that the proximal phalanx 31 is hinged to the connection 34 and thus to the base body 2.
[0058] The connection phalanx 34 is fixed to the base body 2. Alternatively, it is loosely constrained to the base body 2 defining an additional axis of rotation 34a approximately normal to the first axis 31a. Each finger 3 may also comprise return means configured to command a spreading apart between a pair of phalanges 31 , 32 and, if present, 33 and / or 34.
[0059] Preferably, each finger 3 comprises return means interposed between each pair of phalanges 31 , 32, 33 and 34.
[0060] The return means are thus configured to work in opposition to a closing rotation between the phalanges 31 , 32, 33 and 34.
[0061] Preferably, the return means are of elastic type and thus adapted to restore a condition of rest once the cause or stress that caused the displacement of the phalanges 31 , 32, 33 and 34 with respect to the initial condition has been removed.
[0062] For simplicity, said return means, which are known per se, are not shown in the figure.
[0063] The hand 1 comprises a main cable 4 (in detail only one) for controlling the main finger 3a defining a first main end 4a and a second main end 4b opposite said first main end 4a; and at least one actuator associated with at least one of said main ends 4a and 4b and configured to control the main cable 4 by defining a rotation of one or more fingers 3.
[0064] Preferably, the hand 1 comprises a first actuator 5a associated with said first main end 4a and asecond actuator 5b associated with the second main end 4b.
[0065] The at least one actuator is configured to be rigidly constrained to one of the main ends 4a and / or 4b.
[0066] The main cable 4 may be made of polyethylene fibre.
[0067] The main cable 4 therefore defines a main trajectory between the first main end 4a and said second main end 4b.
[0068] The first main end 4a and the second main end 4b are positioned at the base body 2 and thus not constrained to any finger 3.
[0069] To visually clarify the main trajectory of the main cable 4, in Fig. 1 the main cable 4 is represented with a solid line in the points where it is visible and with a dashed line in the points where it is not visible.
[0070] The main cable 4 is slidable within the main finger 3a and suitably in all the phalanges of the main finger 3a.
[0071] To this end, the phalanges 31 , 32 and, if present, 33 of the main finger 3a define one or more main contact surfaces with the main cable 4 and on which said main cable 4 slides causing the movement of the phalanges and thus of the main finger 3a.
[0072] In particular, the main cable 4 is slidable and passes through the main finger 3a twice.
[0073] The main cable 4 may comprise a plurality of segments sequentially arranged without discontinuity defining the main trajectory. In particular, the main cable 4 comprises a first section 4c, a second section 4d, a third section 4e. The first section 4c is configured to control the main finger 3a. It starts from the first end 4a (in detail from the outlet of the cable from the first actuator 5a), slides along part of the base body 2, enters the main finger 3a and slides through the main finger 3a, exiting from it near the base body 2.
[0074] The first section 4c thus travels, as already mentioned, twice through the main finger 3a. In particular, the main finger 3a comprises a referral surface of the main cable 4 configured to allow the cable 4 to enter and exit the main finger 3a and thus the first section 4c passes from the base body 2, enters the main finger 3a, travels through it a first time, engages the referral surface and returns to the base body 2.
[0075] More specifically, the distal phalanx 32 may also define a referral surface of the first section 4c at which the first section 4c inverts its direction of travel through the main finger 3a.Furthermore, each phalanx 31 , 32 and optionally 33 of the main finger 3a features one or more pairs of sliding surfaces of the first section 4c so as to allow the main cable 4 to pass twice through each phalanx.
[0076] Summarising, the first section 4c comprises both an upstream portion of the main finger at the base body 2 and a downstream portion of the main finger 3a also positioned at the base body 2. It therefore slides along the base body 2 reaching the main finger 3a, passes through at least part (in detail, almost the entirety) of the main finger 3a a first time, reaches the referral surface, slides along said referral surface, and passes again through at least part (in detail, almost the entirety) of the main finger 3a and then returns to said base body 2.
[0077] The first section 4c defines at the base body 2 a first lying plane suitably parallel to the prevailing extension surface 2a.
[0078] It is specified that the expression “lying plane” identifies an imaginary plane (optionally also arcuate / curved, but preferably flat) on which lies the barycentric axis / trajectory of the referenced portion of the main cable 4. The second section 4d starts from the second end 4b (in detail from the outlet of the cable from the second actuator 5b) and slides exclusively along part of the base body 2.
[0079] The second section 4d defines a second lying plane suitably parallel to the prevailing extension surface 2a.
[0080] The second lying plane may be parallel to the first lying plane.
[0081] In particular, the second lying plane may be distinct from the first lying plane or, preferably, substantially coplanar with said first plane.
[0082] The third section 4e connects the sections 4c and 4d and slides exclusively along part of the base body 2. The third section 4e defines a third lying plane suitably parallel to the prevailing extension surface 2a.
[0083] It is emphasised that the first section 4c and third section 4e both reach the main finger 3a. Therefore, in order to allow both sections 4c and 4e and thus the main cable 4 to slide controlling the movement of one or more fingers 3, the first lying plane is distinct from the third lying plane so as to allow the third section 4e to override the first section 4c without interference and thus without crossing the first section 4c on the same plane. Preferably, the third section 4e overrides at the main finger 3a withoutcontact with the first section 4c and, therefore, the distance (calculated perpendicularly to the surface 2a) between the first and third lying planes is at least equal to the maximum cross-sectional dimension of the main cable 4.
[0084] The third lying plane may be parallel to the first lying plane.
[0085] The third lying plane is at a greater distance from the prevailing extension surface 2a than the first lying plane.
[0086] The distance of the third lying plane from the prevailing extension surface 2a is different, and in detail greater, preferably also greater than the distance of the second lying plane from said surface 2a. It is emphasised that, at the junction area between the second section 4d and the third section 4e, said sections 4d and 4e are inclined with respect to their respective planes, defining a connection / passage area between the second and third lying planes.
[0087] The base body 2, shown in Fig. 2, comprises a first assembly defining the sliding path of the first section 4c (thus the first lying plane); and a second assembly 2c defining the sliding path of the second section 4d (thus the second lying plane) and a third assembly 2d defining the sliding path of the third section 4e (thus the third lying plane).
[0088] Assemblies 2b, 2c and 2d define circulation surfaces in contact with the main cable 4 and, therefore, are configured to vary the tension of the cable 4 along the main trajectory due to the friction between said circulation surfaces and the main cable 4. In particular, they are configured to vary the tension of the main cable 4 in a monotonic manner (increasing and / or decreasing) between the first end 4a and the second end 4b. As a consequence, the tension of the main cable 4 near the first end 4a is different from the tension of the main cable 4 near the second end 4b.
[0089] With respect to the main trajectory of the main cable 4, the first assembly 2b is upstream of the main finger 3a and the second assembly 2c is downstream of the main finger 3a. In this document, mutual positions such as “upstream”, “downstream” and “interposed” are to be understood along the main trajectory of the main cable 4 in the direction from the first main end 4a toward the second main end 4b.
[0090] The first assembly 2b may comprise at least one first pulley 21 , each defining a first axis of revolution and a first circulation surface of part of the first section 4c of the main cable 4.
[0091] The second assembly 2c comprises at least one second pulley 22, each defining a second axis of revolution and a second circulation surface of the second section 4d.The third assembly 2d comprises at least one third pulley 23 defining a third axis of revolution and a third circulation surface of the third section 4e.
[0092] The first axis of revolution may be substantially perpendicular to the prevailing extension surface 2a. The second axis of revolution may be substantially parallel to the first axis of revolution.
[0093] The second axis of revolution may be substantially perpendicular to the prevailing extension surface 2a.
[0094] The third axis of revolution may be substantially parallel to the first axis of revolution.
[0095] The third axis of revolution may be substantially perpendicular to the prevailing extension surface 2a.
[0096] Preferably, the axes of revolution of pulleys 21 , 22 and 23 are approximately parallel to one another. The first assembly 2b may comprise multiple first pulleys 21 having first axes of revolution substantially parallel to one another and suitably featuring the first projections of the first circulation surfaces, along the normal to the first axes, mutually overlapping. Alternatively, it comprises only one first pulley 21.
[0097] The second assembly 2c may comprise multiple second pulleys 22 having second axes of revolution substantially parallel to one another and suitably featuring the second projections of the second circulation surfaces, along the normal to the second axes, mutually overlapping.
[0098] The third assembly 2d may comprise multiple third pulleys 23 having third axes of revolution substantially parallel to one another and suitably featuring the third projections of the third circulation surfaces mutually overlapping.
[0099] The at least one first projection and the at least one second projection cannot be overlapping, even partially, with respect to first and / or second axes so as to allow the third section 4e to override the first section 4c without interfering therewith.
[0100] Preferably, said at least one first pulley 21 and at least one third pulley 23 are totally non-overlappable with respect to the first and / or third axes so as to allow the third section 4e to override the first section 4c without coming into contact therewith.
[0101] As a consequence, the distance between said first and third projections is at least equal to the maximum cross-sectional dimension of the main cable 4.
[0102] Suitably, the at least one first projection and the at least one second projection are totally overlapping with respect to the third axes.It is specified that in this document the term projection identifies an orthogonal projection, that is, obtained with projection rays perpendicular to the projection plane. As a consequence, the term projection identifies a graphical representation of a three-dimensional object on a projection plane (identifying an imaginary two-dimensional flat surface) onto which said three-dimensional object is projected by projection rays that are perpendicular (or “orthogonal”) to said same projection plane, ensuring that the shadow projected by said rays maintains the exact dimensions and shape of the object and is superimposed thereon along said projection rays. Therefore, for example, the expression “the first projections of the first circulation surfaces, along the normal to the first axes” clearly identifies that such first projections represent a graphical depiction obtained by projecting along the normal to the first axes (consequently the projection rays are normal to the first axes) onto an orthogonal projection plane to the projection rays and thus itself orthogonal to the normal to the first axes.
[0103] It is emphasised that one or more of the second pulleys 22 and one or more of the third pulleys 23 may be stacked with respect to one another and thus have second and third axes of revolution substantially coinciding with one another. In detail, a second pulley 22 may be superimposed and fixed to a third pulley 23 or, alternatively, a second pulley 22 may loosely overlap a third pulley 23 so that pulleys 22 and 23 are able to rotate with respect to one another.
[0104] Assemblies 2b, 2c and 2d define, for their respective sections 4c, 4d and 4e, a lying plane of said section at least partially different from one another.
[0105] As a consequence, the base body 2 also comprises a fourth assembly 2e configured to allow the main cable to pass between distinct lying planes.
[0106] In particular, sections 4c and / or 4d define a lying plane distinct from that of the third section 4e. The fourth assembly 2e is thus preferably interposed between the second assembly 2c and the third assembly 2d and configured to allow the main cable 4 to pass between the second section 4d, arranged along said second lying plane, and the third section 4e lying on said third plane.
[0107] The fourth assembly 2e comprises at least one additional pulley 24 interposed between a third pulley 23 and a second pulley 22. The additional pulley 24 is configured to define the transition between the third section 4e and the second section 4d, thus defining the above-mentioned junction area between the second section 4d and the third section 4e.
[0108] It defines an additional axis of revolution substantially transverse to and, in detail, substantiallyperpendicular to the second axis of revolution and / or to the third axis of revolution.
[0109] The additional pulley 24 also defines an additional circulation surface of the main cable 4.
[0110] Suitably, the fourth assembly 2e comprises two additional pulleys 24; wherein the distance between the additional axes of revolution is adjustable so as to vary the winding angle of the main cable 4 on the same additional pulleys 24, modifying the friction to which the main cable 4 is subjected and thus the tension of said main cable 4. Such adjustment may be carried out during the assembly step of hand 1.
[0111] It is emphasised that, in order to reduce the extension of the artificial hand 1 perpendicularly to the prevailing extension surface 2a, the base body 2 may comprise a hole 2f, suitably a through hole, for at least partial housing of the fourth assembly 2e and, in detail, of one or more additional pulleys 24.
[0112] It is also noted that the base body 2 may in some cases comprise at least one supplementary pulley 25 configured to intercept the main cable near the first main end 4a and / or the second main end 4b. Preferably, the base body 2 comprises only one supplementary pulley 25 configured to intercept the main cable 4 near the second main end 4b downstream of assemblies 2b, 2c and 2d.
[0113] The supplementary pulley 25 may be between the second assembly 2c and the second main end 4b, and precisely between transmission block 7 (introduced below) and the second main end 4b. Pulleys 21 , 22, 23 and, if present, 24 and / or 25 are preferably idly hinged with respect to the base body 2.
[0114] Each actuator 5a and 5b comprises a spool to which a main end 4a or 4b is fixed and a motor configured to control the rotation of the spool, moving the main cable 4 and thus varying its tension. Each spool may feature at least one portion of the main cable wound onto the spool itself.
[0115] Actuators 5a and 5b, and in particular said motor, are preferably of electric type.
[0116] Actuators 5a and 5b may be identical to one another.
[0117] Actuators 5a and 5b are operable independently of one another, for example, causing a different speed (in magnitude and / or direction) of sliding of the main cable 4, i.e., of rotation of the spools. In addition or alternatively, they may be synchronously controlled, for example, defining an equal speed (in magnitude and direction) of sliding of the main cable 4, i.e., of rotation of the spools.
[0118] They are configured to control the rotation of phalanges 31 and 32 and, precisely, of the proximalphalanx 31 with respect to the base body 2 around the first axis of rotation 31a, of the distal phalanx 32 with respect to the proximal phalanx 31 around the second axis of rotation 32a. Additionally, they may also control the rotation of the at least one intermediate phalanx 33 with respect to the third axis of rotation 33a and / or of the connection phalanx 34 with respect to the proximal phalanx 31 around the additional axis of rotation 34a.
[0119] Actuators 5a and 5b may be constrainable to the base body 2. Alternatively, they may be constrained to an external body such as, for example, a medical or robotic arm.
[0120] The artificial hand 1 preferably comprises, for each pair of auxiliary fingers 3, an auxiliary cable 6 for controlling said at least one auxiliary finger 3 and, precisely, the pair of auxiliary fingers 3; and a transmission block 7 configured to allow the main cable 4 to control and thus move the auxiliary cable 6, causing a movement of the pair of auxiliary fingers 3b and 3c. As a consequence, when at least one actuator 5a and / or 5b controls the main cable 4, the first section 4c controls the main finger 3a and the second section 4d controls the pair of auxiliary fingers 3b and 3c, suitably defining for them a movement speed, i.e., rotation between the phalanges, different from that of the main finger 3a. The auxiliary cable 6 is slidable in each of the auxiliary fingers 3b and 3c of the pair of auxiliary fingers and suitably in all the phalanges of said pair. It defines a first auxiliary end associated with a first auxiliary finger 3b and a second auxiliary end opposite the first auxiliary end associated with the other auxiliary finger 3c.
[0121] In particular, phalanges 31 , 32 and, if present, 33 of each auxiliary finger 3b and 3c define at least one (in detail only one) auxiliary contact surface with the auxiliary cable 6 and on which said auxiliary cable 6 slides, causing the movement of the phalanges and thus of the auxiliary finger 3b or 3c. Furthermore, the distal phalanx 32 of auxiliary fingers 3b and 3c comprises an auxiliary fixed constraint of an auxiliary end of the auxiliary cable 6, which therefore features the auxiliary ends fixed to the distal phalanges 32 of the pair of auxiliary fingers 3.
[0122] The auxiliary cable 6 may be, similarly to the main cable 4, made of polyethylene fibre.
[0123] One or more, preferably each, of the transmission blocks 7 comprises for example at least one guide 71 fixed to the base body 2; a carriage 72 slidable along the guide 71 ; a first pulley 73 for sliding the second section 4d hinged to the carriage 72; a second pulley 74 for the sliding of the auxiliary cable 6 hinged to the carriage 72 so that actuator 5a and / or 5b, when operating the main cable 4, cancause a translation of the carriage 72 along the guide 71.
[0124] Preferably, a transmission block 7 comprises two guides 71 parallel to each other and the carriage 72 is slidable along both guides 71.
[0125] Pulleys 73 and 74 may be idly hinged to the carriage 72.
[0126] The translation of the carriage 72, since pulleys 73 and 74 are hinged thereto, causes a displacement of the auxiliary cable 6, thus moving the auxiliary fingers 3.
[0127] In detail, the translation of carriage 72 results in a rotation, suitably in the same direction, of phalanges 31 , 32 and suitably 33 in a first direction. It is emphasised that simultaneously there may occur a rotation of the auxiliary finger 3 with respect to the base body 2 in a first direction, generating the grasp.
[0128] The translation of the carriage 72 may be carried out in opposition to the return means of fingers 3 which, therefore, may define the return of the carriage 72 to the initial position. In detail, the action of the return means of fingers 3 defines a rotation, suitably in the same direction, of phalanges 31 and 32 in a second direction opposite to the first and returning auxiliary fingers 3b and / or 3c to the initial position. The return means of fingers 3 are adapted to maintain tension in the corresponding cable. The guide 71 is linear and defines a sliding axis 71a for the carriage 72. The two guides 71 have sliding axes 71a substantially parallel to each other and suitably to surface 2a.
[0129] Pulleys 73 and 74 define axes of rotation approximately parallel to each other and suitably substantially perpendicular to the sliding axis of the carriage and suitably to surface 2a.
[0130] Alternatively, said axes of rotation may be inclined with respect to one another.
[0131] Preferably, in the case of artificial hand 1 provided with at least one additional finger 3, the hand 1 also comprises an additional cable 8 for controlling the at least one additional finger 3 and an additional transmission block 9 configured to allow the first section 4c to control and thus move the additional cable 8, causing movement of the at least one additional finger 3. As a result, when at least one of actuators 5a and / or 5b controls the main cable 4, the first section 4c also controls the at least one additional finger 3d and / or 3e, defining for it a motion different from that of the at least one auxiliary finger 3b and / or 3c. In fact, the main cable 4, being associated with transmission block 7 at the second section 4d and with the additional transmission block 9 at the first section 4c, can apply to transmission block 7 a tension different from that of additional transmission block 9, causing a distinct movement between auxiliary fingers 3b and / or 3c and additional fingers 3d and / or 3e.In particular, in the case of artificial hand 1 provided with a pair of additional fingers 3d and 3e, the additional cable 8 is configured to control the pair of additional fingers 3d and 3e and, therefore, the additional transmission block 9 is configured to allow the first section 4c to control and thus move the additional cable 8, causing a movement of the pair of additional fingers 3d and 3e. Thus, when at least one of actuators 5a and / or 5b controls the main cable 4, the first section 4c also controls the pair of additional fingers 3d and 3e, defining for said pair of additional fingers 3d and 3e a motion different from that of the pair of auxiliary fingers 3b and 3c.
[0132] The additional cable 8 defines a first additional end associated with the first additional finger 3d and a second additional end associated with the third additional finger 3e.
[0133] The additional cable 8 is slidable in each of the additional fingers 3d and 3e of a pair of additional fingers and suitably in all the phalanges of said pair. It defines a first additional end associated with a first additional finger 3d and a second additional end opposite the first additional end associated with the other additional finger 3e.
[0134] In particular, phalanges 31 , 32 and, if present, 33 of each additional finger define at least one (in detail only one) additional contact surface with the additional cable 8, on which said additional cable 8 slides, causing the movement of the phalanges and thus of the additional finger 3d or 3e. Furthermore, the distal phalanx 32 of the additional finger 3d or 3e comprises a fixed additional constraint of an additional end of the additional cable 8.
[0135] The additional cable 8 may also be made of polyethylene fibre.
[0136] The additional transmission block 9 is upstream of transmission block 7.
[0137] The additional transmission block 9 comprises at least one additional guide 91 fixed to the base body 2; an additional carriage 92 slidable along the additional guide 91; an additional first pulley 93 for sliding the first section 4c hinged to the additional carriage 92; an additional second pulley 94 for sliding the additional cable 8 hinged to the additional carriage 92 so that actuator 5a and / or 5b, when operating the main cable 4, causes a translation of the additional carriage 92 along the additional guide 91.
[0138] The additional transmission block 9 is functionally and dimensionally similarto transmission block 7; therefore, for further details, reference is made to what has been stated above regarding said block 7.
[0139] Preferably, between the additional transmission block 9 and the first end 4a there are no pulleys;thus, the main cable 4 passes from the first actuator 5a to the additional transmission block 9 without sliding on any surface.
[0140] It is emphasised that the main cable 4, being associated with transmission block 7 at the second section 4d and with the additional transmission block 9 at the first section 4c, can apply to transmission block 7 a tension different from that of the additional transmission block 9, causing a distinct movement of auxiliary fingers 3b and 3c with respect to that of additional fingers 3d and 3e. In fact, along the trajectory of the main cable 4 between blocks 7 and 9, there is arranged at least the second assembly 2c and the third assembly 2d which, causing a variation in the tension of the main cable 4, result in the main cable 4 defining a translation of carriage 72 of block 7 different from that of carriage 93 of the additional block 9, causing a different movement between auxiliary fingers 3b and 3c and additional fingers 3d and 3e.
[0141] Summarising, along the main trajectory starting from the first main end 4a (i.e., from the first actuator 5a) toward the second main end 4b (i.e., the second actuator 5b), the main cable 4 sequentially encounters transmission block 7, first assembly 2b, main finger 3a, second assembly 2c, additional block 9, and the possible fifth pulley 25.
[0142] The artificial hand 1 also comprises a control unit adapted to control said hand 1.
[0143] The control unit may be configured to control, suitably as a function of an external signal, the operation of the hand 1. In particular, it is configured to command said at least one actuator 5a and / or 5b to move the main cable 4 and consequently the auxiliary cable 6 and, if present, the additional cable 8. In detail, the unit is configured to control the first actuator 5a and the second actuator 5b, suitably in an independent and / or synchronous manner.
[0144] It is emphasised that, in the case of robotic hand 1 , the control unit may be in data connection with a processor external to hand 1 defining said external signal. Alternatively, in the case of medical artificial hand 1 , the signal may be electromyographic (variation of electric potential during a muscle contraction), and thus the hand 1 may comprise at least one EMG sensor (or prosthetic or myoelectric sensor) adapted to measure a variation of potential in a muscle and transmit to the control unit a signal proportional to such measurement.
[0145] The EMG sensor is known per se.
[0146] The operation of artificial hand 1 , previously described structurally, defines a new actuation processimplementable by the artificial hand 1 and, in detail, controllable by the control unit.
[0147] Initially, the artificial hand 1 is in a state in which fingers 3 and / or 3a are extended, i.e., with the phalanges aligned, defining substantially an extension of surface 2a as shown in Figs. 1 and 2. The actuation process comprises an ordering step in which an external signal is sent to the control unit. Said external signal may require artificial hand 1 to enter a gripping configuration and, for example, grasp an object.
[0148] The actuation process comprises an activation step in which the control unit commands actuators 5a and / or 5b to move the main cable 4, suitably in accordance with said external signal.
[0149] In the activation step, the control unit commands actuators 5a and 5b according to one between a first actuation configuration and a second actuation configuration.
[0150] In the first actuation configuration (Fig. 4), actuators 5a and 5b define a first tension of main cable 4 at the first main end 4a and a second tension of main cable 4 at the second main end 4b, substantially equal to the first tension, consequently determining a synchronous movement of the main finger 3a and auxiliary fingers 3b and 3c, i.e., a rotation speed of fingers 3a, 3b and 3c (in detail of phalanges 31 , 32 and, if present, 33) in the same direction and substantially with the same magnitude.
[0151] The first tension identifies the tension of the first section 4c, while the second tension identifies the tension of the second section 4d.
[0152] In detail, in the first actuation configuration, the control unit commands actuators 5a and 5b to move the main ends 4a and 4b at the same speed and in opposite directions.
[0153] Therefore, actuators 5a and 5b apply the same tension to the two ends 4a and 4b of the main cable 4, which is thus uniformly tensioned between the ends so that sections 4c, 4d and 4e all have the same tension. As a result, the main cable 4 causes a flexion of the main finger 3a and, through transmission block 7, a movement of the auxiliary cable 6 and therefore of auxiliary fingers 3b and 3c.
[0154] Moreover, in the case of artificial hand 1 with additional fingers 3d and 3e and thus with additional transmission block 9 and additional cable 6, the main cable 4, through the additional transmission block 9, also causes movement of the additional cable 8 and thus of additional fingers 3d and 3e, suitably with a speed similar to that of auxiliary fingers 3b and 3c.
[0155] In fact, in the first actuation configuration, the main cable 4, being uniformly tensioned, causes the same displacement of carriage 72 and additional carriage 92. Such identical displacement ofcarriages 72 and 92 corresponds to an identical motion of the auxiliary cable 6 and the additional cable 8 and therefore to the same movement of auxiliary fingers 3b and 3c and additional fingers 3d and 3e.
[0156] In the second actuation configuration (Figs. 5 and 6), actuators 5a and 5b define a first tension different from the second tension. Consequently, the main cable 4 has at the first section 4c a tension different from that of the second section 4d, determining a movement of the first finger 3a not synchronous with auxiliary fingers 3b and 3c, i.e., a rotation speed of fingers 3a, 3b and 3c (in detail of phalanges 31 , 32 and, if present, 33) in the same direction but with different magnitude.
[0157] In detail, in the second actuation configuration, the control unit commands actuators 5a and 5b to move the main ends 4a and 4b at different speeds in magnitude and / or direction. Therefore, actuators 5a and 5b apply different tension to the two ends 4a and 4b, defining at the first section 4c a tension different from that of the second section 4d. Consequently, thanks to the circulation surfaces of at least assemblies 2b, 2c and 2d, the main cable 4 varies in a monotonic manner in tension along the main trajectory. By virtue of this, the main finger 3a moves at a different speed than auxiliary fingers 3b and 3c, defining a gripping configuration different from that of the first actuation configuration. This difference between actuation configurations is accentuated in the case of the presence of additional fingers 3d and 3e and thus of additional transmission block 9 and additional cable 6. In fact, additional fingers 3d and 3e, being actuated by the first section 4c (suitably by the tension applied by first actuator 5a to first main end 4a), move at a speed distinct from that of auxiliary fingers 3b and 3c which are instead actuated by the second section 4d and thus at a tension close to that applied by second actuator 5b to second main end 4b.
[0158] In detail, in Fig. 5, transmission block 7 and additional transmission block 9 define different actions on auxiliary cable 6 and additional cable 8, since carriage 71 is at a greater distance from the finger anchoring point compared to that of additional carriage 92. This position results in different tensioning of cables 6 and 8. This positioning is obtained by defining a tension at the first main end lower than that at the second 4b, thanks to second actuator 5b pulling the second main end 4b and to a compliant first actuator 5a, thus not pulling the first main end 4a.
[0159] Conversely, Fig. 6 shows carriage 71 at a distance from the anchoring point of the fingers smaller than that of additional carriage 92, thanks to a tension at the first main end greater than that of the second 4b.The actuation process may also comprise a release step in which the control unit commands actuators 5a and / or 5b to loosen the tension on the main cable and thus return fingers 3 to the extended position.
[0160] The artificial hand 1 according to the invention achieves important advantages.
[0161] In fact, artificial hand 1 , in addition to allowing the execution of multiple grips of an object, enables manipulation of the same that is particularly simple and easy to control and thus manage. Indeed, hand 1 allows to vary the movement of fingers 3 simply by changing the actuation of actuators 5a and 5b and thus the tension of main cable 4. In particular, especially in the case of hand 1 equipped with additional fingers 3d and 3e and thus with additional transmission block 9 and additional cable 6, artificial hand 1 provides a wide gripping capability without complications in terms of usage and control of the hand itself, which indeed allows automatic adaptation to the object to be grasped. This aspect results both from the possibility of distributing the tension of main cable 4 over the various elements 5, 6, 7 and 9 so that, when some fingers 3 encounter an obstacle during closure, the others continue to close, wrapping around the object.
[0162] Furthermore, the introduction of assemblies 2b, 2c and 2d, allowing during construction to easily vary the number and positions of the circulation surfaces (i.e., pulleys 21 , 22 and 23) on which the main cable 4 slides without mechanical complications, allows to vary and, therefore, adapt the behaviour of hand 1 to various usage conditions.
[0163] A further advantage lies in the fact that artificial hand 1 , despite having an improved and enhanced gripping and object manipulation capability, features a relatively simple mechanical design and is therefore easy to manufacture, compact in size, and low-cost and simple to produce.
[0164] This aspect proves particularly relevant in the medical field, such as in rehabilitation. Indeed, artificial hand 1 could be easily used in rehabilitation sessions aimed at gradually restoring lost motor functions and combating disuse of the paretic limb, for example following a stroke In fact, hand 1 can be controlled in a simple and intuitive way using various interfaces, which can be customised based on the physical stimuli that the user can produce with the impaired limb and the goals of the therapy. This advantage, compared to other known artificial hands used in the same application, is that artificial hand 1 allows for multiple gripping strategies, including advanced and fine grips, and enables manipulation of grasped objects; whereas known artificial hands allow only for gripping objects using a single grip strategy and, above all, do not allow manipulation.For example, the control interface may incorporate force sensors to measure the residual grip strength of the patient’s affected hand, flexion sensors to measure finger flexion / extension, EMG sensors to assess residual muscle activity, and a simple trigger.
[0165] In this application, artificial hand 1 , by enabling more skilled object manipulation with a limited number of control inputs (one for each actuator 5a and 5b), allows for extremely simple execution of repeated movements of a real hand, thus facilitating the recovery of the patient’s affected hand. Indeed, thanks to its peculiar features, hand 1 can be equipped with a biomimetic glove and positioned, for example, underneath or close to the patient’s affected hand so as to conceal it and give the illusion that artificial hand 1 is actually their own paretic limb. The user, by controlling artificial hand 1 via the previously described interfaces, promotes a phenomenon of neural plasticity and motor relearning, which is beneficial for recovering the motor capabilities of the paretic limb.
[0166] Moreover, artificial hand 1 , in addition to being usable during targeted rehabilitation sessions, can also be used in domestic settings thanks to its compact and integrated design. In this case, artificial hand 1 would serve as a compensatory device for motor functions, acting as an assistive device aimed at increasing users’ self-sufficiency in their daily lives.
[0167] These advantages are further enhanced by the fact that artificial hand 1 , using a single mechanical transmission system (i.e., transmission block 7 and the optional additional transmission block 9) and two actuators 5a and 5b, enables the new mechanism of main finger 3a (i.e., the thumb of the anthropomorphic artificial hand 1) to offer a high object manipulation capability by regulating the two actuators 5a and 5b and varying their speed and thus their action on the two ends 4a and 4b (which is not possible with a single actuator).
[0168] It is highlighted that, in the first instance, such advantages (in particular, the fine grips and manipulation not possible with known artificial hands) are made possible by the double passage of main cable 4 within main finger 3a thanks to the fact that the third lying plane of the third section 4d is distinct from the first lying plane of the first section 4b of the main cable 4a, thus allowing the third section 4e (i.e., the main cable 4 exiting the main finger 3a) to cross overthe first section 4c (i.e., the main cable 4 entering the main finger 3a) without reciprocal contact between the first section 4c andthe third section 4e.
[0169] Another advantage is that artificial hand 1 is compact, has high elastic force, is adjustable, reliable, and extremely customisable according to the anthropomorphic shape of each finger.
[0170] Furthermore, the configuration of hand 1 allows the main finger 3a, at least one auxiliary finger 3b and 3c, and one or more additional fingers 3d and 3e to move nearly simultaneously and at the same speed even using a single motor. Indeed, in hand 1 having a single-motor / actuator 5a, actuator 5a retracts the main cable 4 by activating both transmission blocks 7 and 9 (i.e., by pulling both sliders of the two blocks); consequently, by adjusting the tension and stiffness of the elastic joints of hand 1 through the design, it is possible to precisely adjust the speed and delay with which the finger phalanges move all simultaneously and at the same speed if all phalanges have return means and cables with the same stiffness and initial tension. Furthermore, with two motors / actuators, the main cable 4 can slide across the palm more without changing its total active length within the palm; Due to the friction of the main cable 4, this sliding causes the two blocks 7 and 9 to apply different speeds to their sliders, resulting in the closure of the corresponding pairs of auxiliary and supplementary fingers at different speeds. These same design principles can also be applied to regulate the relative motion between all the fingers.
[0171] The invention is susceptible to variations falling within the scope of the inventive concept defined by the claims.
[0172] For example, artificial hand 1 may comprise only one actuator connected to one of the main ends 4a and / or 4b, with the other end firmly attached to artificial hand 1 and, in particular, to the base body 2.
[0173] In another example, artificial hand 1 may comprise only one auxiliary finger 3 (3b or 3c), and thus auxiliary cable 6 commands only that single auxiliary finger.
[0174] In particular, auxiliary cable 6 may define a single path along the auxiliary finger and thus providethe first auxiliary end associated with auxiliary finger 3 and the second auxiliary end associated, for example, with base body 2. Alternatively, auxiliary cable 6 may define two paths along the auxiliary finger and thus provide both auxiliary ends associated with auxiliary finger 3 or both ends associated with base body 2 (in this case, distal phalanx 32 of auxiliary finger 3 defines an auxiliary return surface for auxiliary cable 6).
[0175] In a further example, artificial hand 1 may comprise only one additional finger 3 (3d or 3e), and thus additional cable 8 commands only that single additional finger.
[0176] In particular, additional cable 8 may define a single path along the additional finger and thus provide the first auxiliary end associated with additional finger 3 and the second auxiliary end associated, for example, with base body 2. Alternatively, additional cable 8 may define two paths along additional finger 3 and thus provide both additional ends associated with additional finger 3 or both ends associated with base body 2 (in this case, distal phalanx 32 of additional finger 3 thus defines an auxiliary return surface for additional cable 8).
[0177] Within this scope, all details may be replaced by equivalent elements, and materials, shapes, and dimensions may be of any type.
Claims
CLAIMS1. Artificial hand (1) comprisinga base body (2);a main finger (3a) hinged to said base body (2);at least one auxiliary finger (3b, 3c) hinged to said base body (2);a main cable (4) controlling said main finger (3a) defining a first main end (4a), a second main end (4b) and a main trajectory between said first main end (4a) and said second end (4b);at least one actuator (5a, 5b) associated with at least one of said main ends (4a, 4b) and configured to control said main cable (4) by defining a rotation of said fingers (3a, 3b, 3c); characterized in thatsaid main cable (4) can slide in said main finger (3a) and along base body (2) subdividing said main trajectory and thus said main cable (4) intoo a first section (4c) starting from said first end (4a), which can slide■ along said base body (2) defining a first lying plane and■ in said main finger (3a),o a second section (4d) starting from said second end (4b), can slide along said base body (2) and defining a second lying plane,o a third section (4e) joining said first section (4c) to said second section (4d), sliding along said base body (2) and defining a third lying plane,said third lying plane is distinct from said first lying plane so as to allow said third section (4e) to override said first section (4c) without mutual contact between said first section (4c) and said third section (4e);in thatsaid main finger (3a) includes a referral surface of said main cable (4) and thus said first section (4c)o passes from said base body (2) to said main finger (3a),o runs along said main finger (3a),o slides along said referral surface,o runs again along said main finger (3a), ando returns at said base body (2);in that it comprisesan auxiliary cable (6) controlling said at least one auxiliary finger (3b, 3c);a transmission block (7) configured to associate said second section (4d) with said auxiliary cable (6) so as to enable said second section (4d) and thus said main cable (4) to control said auxiliary cable (6) and thus the movement of said at least one auxiliary finger (3b, 3c) so that, when said at least one actuator (5a, 5b) moves said main cable (4), said first section (4c) moves said main finger (3a) and said second section (4d) moves said at least one auxiliary finger (3b, 3c);characterized in that said base body (2) comprises:a first assembly (2b) defining the sliding path of said first section (4c) at said base body (2); anda second assembly (2c) defining the sliding path of said second section (4d) and said third section (4e);wherein said assemblies (2b, 2c) define circulation surfaces in contact with said main cable (4), varying the tension of said main cable (4) monotonically between said first end (4a) and said second end (4b);wherein said first assembly (2b) includesat least one first pulley (21), each of said at least one first pulley (21) defining a first axis of revolution and a first circulation surface of said first section (4c); andwherein said second assembly (2c) comprises:at least one second pulley (22), each of said at least one second pulley (22) defining a second axis of revolution and a second circulation surface of said second section (4d); and at least one third pulley (23) defining a third axis of revolution and a third circulation surface of said third section (4e);wherein the projection of said first circulation surface of said at least one first pulley (21) is not superimposable on the projection of said third circulation surface of said at least one third pulley (23) along both a normal to said first axis of revolution and a normal to said third axis of revolution; characterized in that:the projection of said second circulation surface of said at least one second pulley (22) is notsuperimposable on the projection of said third circulation surface of said at least one third pulley (23) along both a normal to said second axis of revolution and a normal to said third axis of revolution, so that said second laying plane is distinct from said third laying plane; and wherein said base body (2) comprises a fourth assembly (2e) interposed between said second assembly (2c) and said third assembly (2d), and configured to allow said main cable (4) to pass between said second section (4d) and said third section (4e), and hence between said second laying plane and said third laying plane;and characterized in that:said fourth assembly (2e) comprises at least one additional pulley (24) interposed between said third pulleys (23) and said second pulleys (22), and defining:o an additional axis of revolution substantially transverse to said second axis of revolution and to said third axis of revolution, ando an additional circulation surface of said main cable (4); and wherein said fourth assembly (2e) comprises two of said at least one additional pulley (24), wherein the distance between said additional axes of revolution of said additional pulleys (24) is adjustable so as to vary the wrapping angle of said main cable (4) on said additional pulleys (24), thereby modifying said friction and hence said tension of said main cable (4).
2. Artificial hand (1) according to claim 1 , wherein said at least one actuator (5a, 5b) comprises a first actuator (5a) associated with said first main end (4a) and a second actuator (5b) associated with said second main end (4b) independently controllable with respect to said first actuator (5a).
3. Artificial hand (1) according to any previous claims, wherein said at least one auxiliary finger (3b, 3c) comprises two auxiliary fingers (3b, 3c), each of which is hinged to said base body (2); and wherein said auxiliary cable (6) actuates said pair of auxiliary fingers (3b, 3c), said auxiliary cable (6) defining a first auxiliary end associated with a first one of said auxiliary fingers (3b) and a second auxiliary end associated with a second one of said auxiliary fingers (3c).
4. Artificial hand (1) according to any previous claim, includingat least one additional finger (3d, 3e) hinged to said base body (2) and configured to cooperate with said main finger (3a) and said at least one auxiliary finger (3b, 3c);an additional cable (8) controlling said at least one additional finger (3d, 3e); and an additional transmission block (9) configured to associate said first section (4c) with said additional cable (8) and thereby enable said first section (4c) to actuate and move said additional cable (8),so that when said at least one actuator (5a, 5b) controls said main cable (4) said first section (4c) also controls said at least one additional finger (3d, 3e) defining for said at least one additional finger (3d, 3e) a motion other than said at least one auxiliary finger (3b, 3c); and wherein said second assembly (2c) and said third assembly (2d) are interposed along said main path between said transmission block (7) and said additional transmission block (9).
5. Artificial hand (1) according to the previous claim, wherein said at least one additional finger (3d, 3e) comprises a pair of additional fingers (3d, 3e); wherein said additional cable (8) is configured to command said pair of additional fingers (3d, 3e); wherein said additional cable (8) defines a first additional end associated with a first said additional finger (3d) and a second additional end associated with a second of said additional finger (3e).
6. Artificial hand (1) according to claims 1 and 4, wherein along said main trajectory said main cable (4) sequentially comprises said first end (4a), said additional transmission block (9), said main finger (3), said third assembly (2d), said fourth assembly (2e), said second assembly (2c), said transmission block (7), and said second end (4b).