Mechanical tracking device for upper limb

Abstract

An exoskeletal kinematic system (100) comprising a first frame (10) configured, in use, to be rigidly constrained to the back of a user; a first articulated quadrilateral comprising a first link (101), a first rotational joint (101' ) arranged to allow a rotation of the first link (101) with respect to the first frame (10), a second link (102), a second rotational joint (102' ) arranged to allow a rotation of the second link (102) with respect to the first frame (10), a third link (103), a third rotational joint (103' ) arranged to allow a rotation of the third link (103) with respect to the first link (101), and a fourth rotational joint (104' ) arranged to allow a rotation of the third link (103) with respect to the second link (102); a second articulated quadrilateral comprising a fourth link (104) integrally connected to the third link (103), a fifth link (105), a fifth rotational joint (105' ) arranged to allow a rotation of the fifth link (105) with respect to the fourth link (104), a sixth link (106), a sixth rotational joint (106' ) arranged to allow a rotation of the sixth link (106) with respect to the fourth link (104), a seventh link (107), a seventh rotational joint (107' ) arranged to allow a rotation of the seventh link (107) with respect to the fifth link (105), and an eighth rotational joint (108' ) arranged to allow a rotation of the seventh link (107) with respect to the sixth link (106). The exoskeletal kinematic system (100) further comprises an eighth link (108) integrally connected to the seventh link (107), a ninth link (109), a ninth rotational joint (109' ) arranged to allow a rotation of the ninth link (109) with respect to the eighth link (108), a tenth link (110), a tenth rotational joint (110' ) arranged to allow a rotation of the tenth link (110) with respect to the ninth link (109), an eleventh link (111), an eleventh rotational joint (111' ) arranged to allow a rotation of the eleventh link (111) with respect to the tenth link (110), and a second frame (20) integrally connected to the eleventh link (111) and configured, in use, to be rigidly constrained to an upper limb of the user at the humerus.

Description

TITLEMechanical tracking device for upper limb DESCRIPTIONField of the invention

[0001] The present invention relates to the field of wearable exoskeletons .

[0002] In particular, the present invention relates to an upper limb exoskeleton configurable as a mechanical tracker .Description of the prior art

[0003] As is known, in the field of robotics and wearable exoskeletons, devices capable of spatially tracking the anatomical movements of a user ("motion tracking") are becoming increasingly important, in order to operate in scenarios of virtual reality, support for rehabilitation, telesurgery, teleoperation in environments that are dangerous and hostile to humans, teleoperation in the aerospace field, gaming, teleoperation for simulators, and the like .

[0004] A common methodology adopted to perform teleoperation tasks is the optical type based either on computer vision or on artificial vision. The former involves the combined use of markers and cameras placed in the environment, whereas the latter is based on the processing of images acquired by the cameras . These systems have theadvantage of being ergonomic and versatile, since they are the least cumbersome devices compared with all the other devices . However, they present drawbacks in the estimation of the position of the parts of the hand involved in performing the teleoperation task, for example due to the lack of information between the "leader" (the tracking device worn by the user) and the "follower" (the device that must perform the same movements as the leader) , caused by occlusions due to the interposition of obstacles between the surfaces to be tracked and the devices used for visualizing them.

[0005] An alternative approach is provided by the so-called "smart gloves", devices capable of providing tracking of a user' s hand and generating kinesthetic and tactile feedback capable of simulating the contact with and manipulation of an obj ect . The obj ective of "smart gloves" is to allow the user to manipulate virtual obj ects in a more intuitive and direct manner, in order to improve the immersive sensation and the degree of involvement in virtual or augmented reality. "Smart glove" devices are provided with bending sensors that read the flexion of the fingers and with IMU ( Inertial Measurement Unit) sensors that determine the orientation of the hand, and are characterized by transparency and wearability.

[0006] However, these structural characteristics also involve drawbacks . For example, there are limitations in the accuracy of estimating the flexion of the fingers due to the relative displacement (slippage) between the sensors used for tracking, which remain fixed to the gloves, and the skin of the fingers that slides on the fabric . Moreover, with these devices and depending on the nature of the sensors, the IMU may interfere with electromagnetic devices used for haptic feedback. Another drawback of these devices is the reduced number of degrees of freedom of the fingers that are recorded. In fact, tracking is usually limited to the flexion in the plane of finger closing.

[0007] Another type of devices is represented by the so-called "haptic gloves", which instead exploit kinematic chains mounted in parallel with the fingers of the hand and have the possibility of exerting tactile feedback forces of different nature (tangential or normal) , which are more precise and more easily modulable . Furthermore, there is greater accuracy in estimating the position and orientation of the fingers of the hand, since they allow an actual constraint with the surfaces designated for their fastening.

[0008] However, for most of the applications mentioned above, in addition to tracking the hand it is also necessary to track the entire upper limb connected thereto, in order to simulate the complete movement of the user .

[0009] The document PALAGI MARCELLO et al . , "MULT : a wearable Mechanical Upper Limbs Tracker designed for teleoperation", 2024 IEEE International Conference on Advanced Intelligent Mechatronics (AIM) , IEEE, 15 July 2024, pages 230-235, XP034679112, DOI : 10 . 1109 / AIM55361 . 2024 . 10637044, describes a wearable exoskeletal mechanism for tracking the upper limb based on kinematic chains comprising articulated quadrilaterals and a distal branch that provides the orientation of the humeral interface by means of three revolute joints with mutually perpendicular axes intersecting at a single point, equivalent to a spherical joint .

[0010] Such a configuration, based on three revolute joints with intersecting axes equivalent to a spherical joint, concentrates the orientational degrees of freedom in a single center of rotation. This results in an intrinsic coupling between the rotational movements and a greater sensitivity to manufacturing tolerances and alignment errors, with a possible degradation of the accuracy of reconstruction of the orientation of the limb . Moreover, the concentration of the rotations at a single point may lead to a kinematic behavior that is less distributed along the chain, thereby limiting the possibility of modulating the transmission of the degrees of freedom between the planar structure and the interface with the humerus .Summary of the invention

[0011] It is therefore an obj ect of the present invention to provide a wearable exoskeletal kinematic system capable of providing information relating to the position and orientation of the entire upper limb .

[0012] It is a further obj ect of the present invention to provide such an exoskeletal kinematic system requiring a lower number of sensors than prior-art devices to provide such information relating to the position and orientation of the entire upper limb .

[0013] It is a further obj ect of the present invention to provide such an exoskeletal kinematic system that does not generate parasitic forces on the joints and that is adaptable to different anthropometric dimensions of the user .

[0014] These and other obj ects are achieved by an exoskeletal kinematic system according to claims 1 to 10.

[0015] According to another aspect of the invention, a hand exoskeleton according to claim 11 is also claimed.

[0016] According to a further aspect of the invention, an upper limb exoskeleton according to claim 12 is also claimed .Brief description of the drawings

[0017] The invention will be illustrated below by means of the following description of some embodiments thereof, provided by way of example and not of limitation, with reference to the attached drawings in which:figure 1 shows the kinematic diagram of a first embodiment of the exoskeletal kinematic system according to the present invention;figure 2 shows the kinematic diagram of a second embodiment of the exoskeletal kinematic system according to the present invention;figure 3 shows the second embodiment of the exoskeletal kinematic system according to the present invention;figure 3A shows a detail of figure 3;figures 4A and 4B schematically show the movement of the first articulated quadrilateral;figures 5A and 5B schematically show the movement of the second articulated quadrilateral;figure 6 shows in detail the movement of the first articulated quadrilateral;figure 7 shows the proportions between the lengths of the links of a portion of the exoskeletal kinematic system;figure 8 shows the kinematic diagram of a first finger exoskeleton;figure 9 shows the kinematic diagram of a second finger exoskeleton;figure 10 shows a possible embodiment of a first finger exoskeleton;figure 11 shows a possible embodiment of a second finger exoskeleton;figure 12 shows a possible embodiment of the complete hand exoskeleton;figure 13 shows a third embodiment of the exoskeletal kinematic system according to the present invention.Description of some preferred embodiments

[0018] With reference to figure 1, in a first embodiment, the exoskeletal kinematic system 100 comprises a first frame 10 configured, in use, to be rigidly constrained to the back of a user . The first frame 10 defines a reference system S comprising axes x, y and z fixed with respect to the frame 10 itself .

[0019] The exoskeletal kinematic system 100 further comprises a first articulated quadrilateral comprising: a first link 101 ;a first rotational joint 101' arranged to allow a rotation of the first link 101 with respect to the first frame 10 about an axis Zi parallel to the axis z ;a second link 102 ;a second rotational joint 102' arranged to allow a rotation of the second link 102 with respect to the first frame 10 about an axis z2parallel to the axis z ;a third link 103;a third rotational joint 103' arranged to allow a rotation of the third link 103 with respect to the first link 101 about an axis z3parallel to the axis z ;a fourth rotational joint 104' arranged to allow a rotation of the third link 103 with respect to the second link 102 about an axis z4parallel to the axis z .

[0020] The exoskeletal kinematic system 100 further comprises a second articulated quadrilateral comprising: a fourth link 104 integrally connected to the third link 103;a fifth link 105;a fifth rotational joint 105' arranged to allow a rotation of the fifth link 105 with respect to the fourth link 104 about an axis yi parallel to the axis y;a sixth link 106;a sixth rotational joint 106' arranged to allow a rotation of the sixth link 106 with respect to thefourth link 104 about an axis y2parallel to the axis y;a seventh link 107 ;a seventh rotational joint 107' arranged to allow a rotation of the seventh link 107 with respect to the fifth link 105 about an axis y3parallel to the axis y;an eighth rotational joint 108' arranged to allow a rotation of the seventh link 107 with respect to the sixth link 106 about an axis y4parallel to the axis y-

[0021] Furthermore, the exoskeletal kinematic system 100 comprises :an eighth link 108 integrally connected to the seventh link 107 ;a ninth link 109;a ninth rotational joint 109' arranged to allow a rotation of the ninth link 109 with respect to the eighth link 108 about an axis z7parallel to the axis z ;a tenth link 110;a tenth rotational joint 110' arranged to allow a rotation of the tenth link 110 with respect to the ninth link 109 about an axis y5orthogonal to the axisan eleventh link 111 ;an eleventh rotational joint 111' arranged to allow a rotation of the eleventh link 111 with respect to the tenth link 110 about an axis x3orthogonal to the axis Ys;a second frame 20 integrally connected to the eleventh link 111 and configured, in use, to be rigidly constrained to an upper limb of the user at the humerus .

[0022] Advantageously, each joint of a plurality of selected rotational joints comprises a respective sensor configured to measure the magnitude of the performed rotation and to communicate such measurements to a control unit, such that the control unit can calculate the spatial position of the second frame 20 with respect to the reference system S .

[0023] In particular, the plurality of selected rotational joints comprises :a rotational joint selected from the group consisting of the first rotational joint 101' , the second rotational joint 102' , the third rotational joint 103' and the fourth rotational joint 104' ;a rotational joint selected from the group consisting of the fifth rotational joint 105' , the sixth rotational joint 106' , the seventh rotational joint107' and the eighth rotational joint 108' ;the ninth rotational joint 109' ;the tenth rotational joint 110' ;the eleventh rotational joint 111' .

[0024] In particular, with reference also to figures 3A, 4A, 4B and 6, the first link 101 comprises a first end 101a and a second end 101b constrained to each other by means of a prismatic joint arranged to allow a relative translation along an axis Xi orthogonal to the axis Zi, while the second link 102 comprises a first end 102a and a second end 102b constrained to each other by means of a prismatic joint arranged to allow a relative translation along an axis x2orthogonal to the axis z2. Furthermore, the first articulated quadrilateral is configured such that the third link 103 is constrained to perform a translation with respect to the fourth link 104 along an axis ytparallel to the axis y.

[0025] Similarly, with reference to figures 3A, 5A and 5B, the fifth link 105 comprises a first end 105a and a second end 105b constrained to each other by means of a prismatic joint arranged to allow a relative translation along an axis z5orthogonal to the axis yi, while the sixth link 106 comprises a first end 106a and a second end 106b constrained to each other by means of a prismatic joint arranged to allow a relative translation along an axis z6orthogonal tothe axis y2. Furthermore, the second articulated quadrilateral is configured such that the seventh link 107 is constrained to perform a translation with respect to the fourth link 104 along an axis xtparallel to the axis x .

[0026] Advantageously, furthermore, the first articulated quadrilateral comprises :a first elastic element 101* configured to generate an elastic force Fe ibetween the first end 101a and the second end 101b of the first link 101, said elastic force Fei having a direction parallel to the axis xpa second elastic element 102* configured to generate an elastic force Fe2 between the first end 102a and the second end 102b of the second link 102, said elastic force Fe2 having a direction parallel to the axis x2;a first constraint system configured to prevent the elastic forces Fei and Fe2 from producing a translation of the third link 103 along a direction perpendicular to the axis yt.

[0027] In particular, the first constraint system comprises two rolling bearings 103* and the elastic forces Fei and Fe2 generated by the two elastic elements 101* and 102* ensure that the third link 103 is constantly in contact with said rolling bearings 103* , such that the third link103 is constrained to translate along the axis ytwith only rolling friction.

[0028] Advantageously, furthermore, the second articulated quadrilateral comprises :a third elastic element 105* configured to generate an elastic force Fes between the first end 105a and the second end 105b of the fifth link 105, said elastic force Fes having a direction parallel to the axis z5;a fourth elastic element 106* configured to generate an elastic force Fe4 between the first end 106a and the second end 106b of the sixth link 106, said elastic force Fe4 having a direction parallel to the axis z6;a second constraint system configured to prevent the elastic forces Fes and Fe4 from producing a translation of the seventh link 107 along a direction perpendicular to the axis xt.

[0029] In particular, the second constraint system comprises two rolling bearings 107* and the elastic forces Fes and Fe4 generated by the two elastic elements 105* and 106* ensure that the seventh link 107 is constantly in contact with said rolling bearings 107* , such that the seventh link 107 is constrained to translate along the axis xtwith only rolling friction.

[0030] In this way, the first and the second articulated quadrilateral behave exactly as two pure prismatic joints, but with the advantage of avoiding sticking due to friction that a prismatic joint could generate as a result of undesired forces transverse to the direction of translation.

[0031] Furthermore, the replacement of prismatic joints with rotational joints allows tracking of the position of the kinematic mechanism by means of rotational encoders, which are simpler and less expensive than linear encoders .

[0032] Advantageously, the eleventh link 111 comprises a first end Illa and a second end 111b constrained to each other by means of a prismatic joint arranged to allow a relative translation along an axis z8orthogonal to the axis x3. Furthermore, the second frame 20 is integrally connected to the second end 111b of the eleventh link 111.

[0033] Furthermore, with reference also to figure 7, there are also provided:a first auxiliary link 121 ;a first auxiliary rotational joint 121' arranged to allow a rotation of the first auxiliary link 121 with respect to the first end Illa of the eleventh link 111 ;a second auxiliary link 122 ;a second auxiliary rotational joint 122' arranged to allow a rotation of the second auxiliary link 122 withrespect to the first auxiliary link 121 ;a third auxiliary rotational joint 123' arranged to allow a rotation of the second auxiliary link 122 with respect to the second end 111b of the eleventh link 111 .

[0034] In this way it is possible to measure the relative translation between the first end Illa and the second end 111b of the eleventh link 111 by means of the magnitude of the rotation measured by an encoder, or rotational sensor, placed on only one of the auxiliary rotational joints 121' , 122' or 123' .

[0035] In particular, the relationship between the position s of the prismatic joint and the angle read by the encoder is s = 2L -cos0.

[0036] With reference also to figures 2 and 3, in a second embodiment the exoskeletal kinematic system 100, in addition to comprising all the components of the first embodiment, further comprises :a twelfth link 112 integrally connected to the eleventh link 111 and to the second frame 20;a thirteenth link 113;a twelfth rotational joint 112' arranged to allow a rotation of the thirteenth link 113 with respect to the twelfth link 112 about an axis y6;a fourteenth link 114 ;a thirteenth rotational joint 113' arranged to allow a rotation of the fourteenth link 114 with respect to the thirteenth link 113 about an axis x4orthogonal to the axis y6;a fifteenth link 115;a fourteenth rotational joint 114' arranged to allow a rotation of the fifteenth link 115 with respect to the fourteenth link 114 about an axis x5parallel to the axis x4;a sixteenth link 116;a fifteenth rotational joint 115' arranged to allow a rotation of the sixteenth link 116 with respect to the fifteenth link 115 about an axis x6parallel to the axis x5;a seventeenth link 117 ;a sixteenth rotational joint 116' arranged to allow a rotation of the seventeenth link 117 with respect to the sixteenth link 116 about an axis z9orthogonal to the axis y6;a third frame 30 configured, in use, to be rigidly constrained to an upper limb of the user at the hand; a seventeenth rotational joint 117 ' arranged to allow a rotation of the seventeenth link 117 with respect to the third frame 30 about an axis y7orthogonal to the axis z9.

[0037] Advantageously, in this second embodiment, the rotational joints 112' , 113' , 114' , 115' , 116' , 117' , in addition to the rotational joints previously mentioned, are also provided with encoders, or rotational sensors, configured to measure the magnitude of the performed rotation and to communicate such measurements to a control unit, such that the control unit can calculate the spatial position of the third frame 30 with respect to the reference system S .

[0038] In particular, with reference to figure 3, the axis x6of the fifteenth rotational joint 115' , the axis z9of the sixteenth rotational joint 116' and the axis y7of the seventeenth rotational joint 117 ' intersect at a point A.

[0039] In this way the rotational joints 115' , 116' and 117' are equivalent to a spherical joint having its center at the point A that connects the fifteenth link 115 with the third frame 30.

[0040] With reference to figures 8 to 12, the present invention also comprises a hand exoskeleton 200 comprising a support frame 205, a first finger exoskeleton 210 configured, in use, to be applied to the thumb and the little finger of a user, and a second finger exoskeleton 220 configured, in use, to be applied to the index finger, the middle finger and the ring finger of a user .

[0041] In particular, the first finger exoskeleton 210 comprises :a first link 211 ;a first rotational joint 211' arranged to allow a rotation of the first link 211 with respect to the support frame 205 about an axis ai;a second link 212 ;a second rotational joint 212' arranged to allow a rotation of the second link 212 with respect to the first link 211 about an axis bi orthogonal to the axis 31a third link 213;a third rotational joint 213' arranged to allow a rotation of the third link 213 with respect to the second link 212 about an axis b2parallel to the axis bi;a fourth link 214 ;a fourth rotational joint 214' arranged to allow a rotation of the fourth link 214 with respect to the third link 213 about an axis b3parallel to the axis bi;a fifth link 215;a fifth rotational joint 215' arranged to allow a rotation of the fifth link 215 with respect to the fourth link 214 about an axis Ci orthogonal to theaxis ai and to the axis bi;a sixth link 216;a sixth rotational joint 216' arranged to allow a rotation of the sixth link 216 with respect to the fifth link 215 about an axis a2orthogonal to the axis bi and to the axis Ci;a constraint element 219 integrally connected to the sixth link 216 and configured to be rigidly constrained to a distal phalanx of the finger of the user .

[0042] In particular, the second finger exoskeleton 220 comprises :a first link 221 ;a first rotational joint 221' arranged to allow a rotation of the first link 221 with respect to the support frame 205 about an axis di;a second link 222 ;a second rotational joint 222' arranged to allow a rotation of the second link 222 with respect to the first link 221 about an axis ei orthogonal to the axis di;a third link 223;a third rotational joint 223' arranged to allow a rotation of the third link 223 with respect to the second link 222 about an axis e2parallel to the axisSi ;a first constraint element 228 configured to be rigidly constrained to an intermediate phalanx of the finger of the user, and being connected to the third link 223 by means of a first spherical joint 228' ; a fourth link 224 ;a fourth rotational joint 224' arranged to allow a rotation of the fourth link 224 with respect to the third link 223 about an axis d2parallel to the axis di;a fifth link 225;a fifth rotational joint 225' arranged to allow a rotation of the fifth link 225 with respect to the fourth link 224 about an axis e3parallel to the axis 6i ;a sixth link 226;a sixth rotational joint 226' arranged to allow a rotation of the sixth link 226 with respect to the fifth link 225 about an axis e4parallel to the axis 6i ;a second constraint element 229 configured to be rigidly constrained to the distal phalanx of the finger of the user, and being connected to the sixth link 226 by means of a second spherical joint 229' .

[0043] In particular, with reference also to figure 13, the present invention also claims an upper limb exoskeleton 300 comprising the combination of the exoskeletal kinematic system 100 of figure 3 with the hand exoskeleton 200 of figure 12, wherein the support frame 205 of the hand exoskeleton 200 is integrally connected to the third frame 30 of the exoskeletal kinematic system 100.

[0044] In particular, in the upper limb exoskeleton 300 the rotational joints 211' , 212' , 213' , 214' , 215' , 221' , 222' , 223' , 224 ' , 225' and 226' , in addition to the rotational joints previously mentioned, are provided with encoders, or rotational sensors, configured to measure the magnitude of the performed rotation and to communicate such measurements to a control unit, such that the control unit can calculate the spatial position of each constraint element 219 and 229, that is of each distal phalanx of each finger, with respect to the reference system S .

Claims

CLAIMS1 . An exoskeletal kinematic system ( 100 ) comprising :- a first frame ( 10 ) arranged, in use , to be integrally constrained to the back of a user, said first frame ( 10 ) defining a reference system S comprising the axes x, y and z ;- a first articulated quadrilateral comprising :— a first link ( 101 ) ;— a first rotational j oint ( 101 ' ) arranged to allow a rotation of said first link ( 101 ) with respect to said first frame ( 10 ) about an axis zi parallel to said axis z ;— a second link ( 102 ) ;— a second rotational j oint ( 102 ’ ) arranged to allow a rotation of said second link ( 102 ) with respect to said first frame ( 10 ) about an axis Z2 parallel to said axis z ;— a third link ( 103 ) ;— a third rotational j oint ( 103 ’ ) arranged to allow a rotation of said third link ( 103 ) with respect to said first link ( 101 ) about an axis Z3 parallel to said axis z ;— a fourth rotational j oint ( 104 ’ ) arranged to allow a rotation of said third link ( 103 ) with respect to said second link ( 102 ) about an axis Z4parallel to said axis z ;- a second articulated quadrilateral comprising :— a fourth link ( 104 ) integrally connected to said third link ( 103 ) ;— a fi fth link ( 105 ) ;— a fi fth rotational j oint ( 105 ’ ) arranged to allow a rotation of said fi fth link ( 105 ) with respect to said fourth link ( 104 ) about an axis yi parallel to said axis y;— a sixth link ( 106 ) ;— a sixth rotational j oint ( 106 ’ ) arranged to allow a rotation of said sixth link ( 106 ) with respect to said fourth link ( 104 ) about an axis y2 parallel to said axis y;— a seventh link ( 107 ) ;— a seventh rotational j oint ( 107 ’ ) arranged to allow a rotation of said seventh link ( 107 ) with respect to said fi fth link ( 105 ) about an axis ya parallel to said axis y;— an eighth rotational j oint ( 108 ’ ) arranged to allow a rotation of said seventh link ( 107 ) with respect to said sixth link ( 106 ) about an axis y4 parallel to said axis y;- an eighth link ( 108 ) integrally connected to said seventh link ( 107 ) ;said exoskeletal kinematic system ( 100 ) characterized in that it further comprises :- a ninth link ( 109 ) ;- a ninth rotational j oint ( 109 ’ ) arranged to allow a rotation of said ninth link ( 109 ) with respect to said eighth link ( 108 ) about an axis z? parallel to said axis z ;- a tenth link ( 110 ) ;- a tenth rotational j oint ( 110 ' ) arranged to allow a rotation of said tenth link ( 110 ) with respect to said ninth link ( 109 ) about an axis ys orthogonal to said axis z? ;- an eleventh link ( 111 ) ;- an eleventh rotational j oint ( 111 ' ) arranged to allow a rotation of said eleventh link ( 111 ) with respect to said tenth link ( 110 ) about an axis X3 orthogonal to said axis ys ;- a second frame ( 20 ) integrally connected to said eleventh link ( 111 ) , said second frame ( 20 ) arranged, in use , to be integral ly constrained to an upper limb of said user at the humerus .2 . The exoskeletal kinematic system ( 100 ) , according to claim 1 , wherein :- said first link ( 101 ) comprises a first end ( 101a ) and a second end ( 101b ) constrained to each otherby means of a prismatic joint arranged to allow a relative translation along an axis xi orthogonal to said axis zi;- said second link ( 102 ) comprises a first end ( 102a) and a second end ( 102b) constrained to each other by means of a prismatic joint arranged to allow a relative translation along an axis X2 orthogonal to said axis Z2;said first articulated quadrilateral being configured in such a way that said third link ( 103) is constrained to carry out a translation with respect to said fourth link ( 104 ) along an axis y? parallel to said axis y.

3. The exoskeletal kinematic system ( 100) , according to claim 1, wherein:- said fifth link ( 105) comprises a first end ( 105a) and a second end ( 105b) constrained to each other by means of a prismatic joint arranged to allow a relative translation along an axis Z5 orthogonal to said axis yi;- said sixth link ( 106) comprises a first end ( 106a) and a second end ( 106b) constrained to each other by means of a prismatic joint arranged to allow a relative translation along an axis ze orthogonal to said axis y2,-said second articulated quadrilateral being configuredin such a way that said seventh link ( 107 ) is constrained to carry out a trans lation with respect to said fourth link ( 104 ) along an axis X parallel to said axis x .4 . The exoskeletal kinematic system ( 100 ) , according to claim 2 , wherein said first articulated quadrilateral comprises :- a first elastic element ( 101* ) arranged to generate an elastic force Feibetween said first end ( 101a ) and said second end ( 101b ) of said first link ( 101 ) , said elastic force Feihaving a direction parallel to said axis xi;- a second elastic element ( 102 * ) arranged to generate an elastic force Fe2 between said first end ( 102a ) and said second end ( 102b ) of said second link ( 102 ) , said elastic force Fe2 having a direction parallel to said axis X2 ;- a first constraint system arranged to avoid that said elastic forces Feiand Fe2 produce a translation of said third link ( 103 ) along a direction perpendicular to said axis y? .5 . The exoskeletal kinematic system ( 100 ) , according to claim 3 , wherein said second articulated quadrilateral comprises :a third elastic element ( 105* ) arranged to generatean elastic force Fe3 between said first end ( 105a ) and said second end ( 105b ) of said fi fth link ( 105 ) , said elastic force Fe3 having a direction parallel to said axis zs ;- a fourth elastic element ( 106* ) arranged to generate an elastic force Fe4 between said first end ( 106a ) and said second end ( 106b ) of said sixth link ( 106 ) , said elastic force Fe4 having a direction parallel to said axis ze;- a second constraint system arranged to avoid that said elastic forces Fe3 and Fe4 produce a translation of said seventh link ( 107 ) along a direction perpendicular to said axis XT .

6. The exoskeletal kinematic system ( 100 ) , according to claim 1 , wherein said eleventh link ( 111 ) comprises a first end ( I l la ) and a second end ( 111b ) constrained to each other by means of a prismatic j oint arranged to allow a relative translation along an axis zg orthogonal to said axis X3, said second frame ( 20 ) being integrally connected to said second end ( 111b ) of said eleventh link ( 111 ) .7 . The exoskeletal kinematic system ( 100 ) , according to claim 6 , wherein there are also comprised :- a first auxiliary link ( 121 ) ;a first rotational auxiliary j oint ( 121 ' ) arrangedto allow a rotation of said first auxiliary link ( 121 ) with respect to said first end ( I l la ) of said eleventh link ( 111 ) ;- a second auxiliary link ( 122 ) ;- a second rotational auxiliary j oint ( 122 ’ ) arranged to allow a rotation of said second auxiliary link ( 122 ) with respect to said first auxiliary link ( 121 ) ;- a third rotational auxiliary j oint ( 123 ’ ) arranged to allow a rotation of said second auxiliary link ( 122 ) with respect to said second end ( 111b ) of said eleventh link ( 111 ) .8 . The exoskeletal kinematic system ( 100 ) , according to claim 1 , wherein there are also comprised :- a twel fth link ( 112 ) integrally connected to said eleventh link ( 111 ) and to said second frame ( 20 ) ; - a thirteenth link ( 113 ) ;- a twel fth rotational j oint ( 112 ’ ) arranged to allow a rotation of said thirteenth link ( 113 ) with respect to said twel fth link ( 112 ) about an axis ye;- a fourteenth link ( 114 ) ;- a thirteenth rotational j oint ( 113 ’ ) arranged to allow a rotation of said fourteenth link ( 114 ) with respect to said thirteenth link ( 113 ) about an axisX4 orthogonal to said axis ye;- a fifteenth link ( 115) ;- a fourteenth rotational joint ( 114 ’ ) arranged to allow a rotation of said fifteenth link ( 115) with respect to said fourteenth link ( 114 ) about an axis xs parallel to said axis X4;- a sixteenth link ( 116) ;- a fifteenth rotational joint ( 115 ’ ) arranged to allow a rotation of said sixteenth link ( 116) with respect to said fifteenth link ( 115) about an axis xe parallel to said axis X5;- a seventeenth link ( 117 ) ;- a sixteenth rotational joint ( 116 ’ ) arranged to allow a rotation of said seventeenth link ( 117 ) with respect to said sixteenth link ( 116) about an axis Z9 orthogonal to said axis ye;- a third frame (30) arranged, in use, to be integrally constrained to an upper limb of said user at the hand;- a seventeenth rotational joint ( 117 ’ ) arranged to allow a rotation of said seventeenth link ( 117 ) with respect to said third frame (30) about an axis y? orthogonal to said axis Z9.

9. The exoskeletal kinematic system ( 100) , according to claim 8, wherein said axis xe of said fifteenthrotational j oint ( 115 ' ) , said axis zg of said sixteenth rotational j oint ( 116 ' ) and said axis y? of said seventeenth rotational j oint ( 117 ’ ) are incident at a point A.10 . The exoskeletal kinematic system ( 100 ) , according to claim 1 , wherein each j oint of a plurality of selected rotational j oints comprises a relative sensor configured to measure the amount of rotation performed and to communicate such measurements to a control unit , in such a way that said control unit can calculate the spatial position of said second frame ( 20 ) with respect to said reference system S , said plurality of selected rotational j oints comprising :- a rotational j oint selected from the group consisting of said first rotational j oint ( 101 ' ) , said second rotational j oint ( 102 ' ) , said third rotational j oint ( 103 ’ ) and said fourth rotational j oint ( 104 ' ) ;- a rotational j oint selected from the group consisting of said fi fth rotational j oint ( 105 ' ) , said sixth rotational j oint ( 106 ' ) , said seventh rotational j oint ( 107 ’ ) and said eighth rotational j oint ( 108 ' ) ;- said ninth rotational j oint ( 109 ' ) ;- said tenth rotational j oint ( 110 ' ) ;said eleventh rotational joint ( 111' ) .

11. A hand exoskeleton (200) comprising:- a support frame (205) ;- at least a first finger exoskeleton (210) comprising :— a first link (211 ) ;— a first rotational joint ( 211 ’ ) arranged to allow a rotation of said first link (211 ) with respect to said support frame (205) about an axis ai;— a second link (212 ) ;— a second rotational joint ( 212 ’ ) arranged to allow a rotation of said second link (212 ) with respect to said first link (211 ) about an axis bi orthogonal to said axis ai;— a third link (213) ;— a third rotational joint ( 213 ’ ) arranged to allow a rotation of said third link (213) with respect to said second link (212 ) about an axis b2 parallel to said axis bi;— a fourth link (214 ) ;— a fourth rotational joint ( 214 ’ ) arranged to allow a rotation of said fourth link (214 ) with respect to said third link (213) about an axis ba parallel to said axis bi;a fifth link (215) ;— a fifth rotational joint ( 215 ' ) arranged to allow a rotation of said fifth link (215) with respect to said fourth link (214 ) about an axis ci orthogonal to said axis ai and to said axis bi; — a sixth link (216) ;— a sixth rotational joint ( 216 ’ ) arranged to allow a rotation of said sixth link (216) with respect to said fifth link (215) about an axis a2 orthogonal to said axis bi and to said axis ci; — a constraint element (219) integrally connected to said sixth link (216) and arranged to be integrally constrained to a phalanx of a finger of a user;- at least a second finger exoskeleton (220) comprising :— a first link (221 ) ;— a first rotational joint ( 221 ’ ) arranged to allow a rotation of said first link (221 ) with respect to said support frame (205) about an axis di;— a second link (222 ) ;— a second rotational joint (222' ) arranged to allow a rotation of said second link (222 ) with respect to said first link (221 ) about an axis eiorthogonal to said axis di;— a third link (223) ;— a third rotational joint ( 223 ’ ) arranged to allow a rotation of said third link (223) with respect to said second link (222 ) about an axis 62 parallel to said axis ei;— a first constraint element (228 ) arranged to be integrally constrained to a phalanx of a finger of a user, said third link (223) being connected to said first constraint element (228 ) by means of a first spherical joint (228' ) ;— a fourth link (224 ) ;— a fourth rotational joint ( 224 ’ ) arranged to allow a rotation of said fourth link (224 ) with respect to said third link (223) about an axis d2 parallel to said axis di;— a fifth link (225) ;— a fifth rotational joint ( 225 ’ ) arranged to allow a rotation of said fifth link (225) with respect to said fourth link (224 ) about an axis 63 parallel to said axis ei;— a sixth link (226) ;— a sixth rotational joint ( 226 ’ ) arranged to allow a rotation of said sixth link (226) with respect to said fifth link (225) about an axis 64parallel to said axis ei;— a second constraint element (229) arranged to be integrally constrained to a phalanx of a finger of a user, said sixth link (226) being connected to said second constraint element (229) by means of a second spherical joint ( 229 ’ ) .

12. An upper limb exoskeleton (300) comprising the exoskeletal kinematic system ( 100) according to claim 8 and the hand exoskeleton (200) according to claim 11, wherein said third frame (30) is integrally connected to said support frame (205) .

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