Robotic device for passive compensation of an external force

Abstract

A robotic device (100) for the passive compensation of an external force Fext comprising a frame (101) arranged to define a reference system S having axes x and y lying on a plane Π; a first loading arm (110) rotatably connected to the frame (101) by means of a first rotational constraint (115) arranged to allow a relative rotation between the first loading arm (110) and the frame (101) around a rotation axis z1 orthogonal to the plane Π, the rotation axis z1 intersecting the plane H in a rotation center 0 having coordinates x0 and y0, the first loading arm (110) comprising a point C1 lying on the plane Π, the segment OC1 having length L1 and forming an angle with respect to the axis x, the first loading arm (110) also comprising a point Bt arranged on the segment OC1, the segment OB1 having length b1; an adjustment element (105) connected to the frame (101) by a constraint having one degree of freedom, the adjustment element (105) comprising a point A lying on the plane Π and having coordinates xA and yA, where yA — y0 = α, α being an adjustment parameter; a first transmission system comprising a first transmission element (150); a first elastic element (130) having a first elastic constant k1 and arranged to generate a first elastic force Fel1, the first elastic element (130) comprising a first end (131) integral with the adjustment element (105) and a second end (132) connected to the first transmission element (150) at a first end (151) of the first transmission element (150). In particular, the first transmission system is configured in such a way that, through the first transmission element (150), the first elastic force Fel1 generates a first interaction force Fint1 = r1 * Fel1 acting on the first loading arm (110), where rt is a first transmission factor, the first interaction force Fint1 having direction parallel to the segment AB1 and passing through the point B1. The robotic device (100) then comprises an actuator (170) arranged to move the adjustment element (105) with respect to the frame (101) to vary the coordinate yA. The robotic device (100) also comprises a control unit arranged, following an external command, to operate the actuator (170) to move the adjustment element (105) in order to pass between a first configuration, in which α = α1 and a second configuration, in which α = α2, where α1 and α2 are two determined values of the adjustment parameter α.

Description

TITLERobotic device for passive compensation of an external force DESCRIPTIONField of the invention

[0001] The present invention relates to the technical field of wearable exoskeletons for assisting in li fting loads .

[0002] In particular, the present invention relates to a robotic device and an exoskeleton for passively compensating an external force .Description of the prior art

[0003] Exoskeletons are mechanical and / or robotic systems that can be worn and are designed with the unique feature of following and / or supporting the movements of the human limbs with which they interact . Among the fields of application for exoskeletons are rehabilitation, assistance , support and enhancement .

[0004] Exoskeletons for load handling support are wearable devices designed to provide forces or torques at the points of connection with the wearer in order to provide physical support in the work being performed . When worn, these exoskeletons provide an alternative path through which to trans fer the loads present at the most distal anchor point of the device to the anchor point closest to the person .This allows the muscles and joints between the two anchor points of the device to be fully or partially relaxed.

[0005] Exoskeletons can be totally active, i.e. equipped with actuators that directly generate the torques / forces necessary to compensate for the external force, with continuous energy consumption throughout the compensation phase, or totally passive, capable of generating such forces / torques without requiring any energy consumption throughout the external force compensation phase. In particular, totally passive exoskeletons consist of an articulated structure on which appropriate elastic elements act to generate the forces / torques necessary to transfer the load from a distal point on the person's body to a proximal point on the body or directly to the ground. Compared to fully active solutions, passive exoskeletons offer greater simplicity of construction, robustness, lightness and virtually infinite autonomy, as they consume no energy.

[0006] There are also examples of exoskeletons with hybrid actuation, i.e. equipped with both elastic elements and actuators, the latter being used exclusively to modify the value of the external force to be compensated.

[0007] For this type of exoskeleton, energy consumption is therefore limited to the phases of modifying the externalforce to be compensated, as only the elastic elements and not the actuators are required for compensation .

[0008] An example of a hybrid actuation exoskeleton is shown in EP2948276 , which describes a robotic device for assisting human body movements comprising a frame having a fixed point A and an articulation point 0 located at a distancei, and a proximal arm hinged to the frame at the articulation point 0. The device also comprises an elastic element , connected to the proximal arm and to the frame , designed to generate an interaction force on the proximal arm . The device also comprises a carriage , comprising a balancing point B located at a distance bi from the articulation point 0, and designed to move along the proximal arm to vary this distance bi in order to vary the interaction force generated .

[0009] This robotic device provides ef fective passive compensation for the li fting of a load, but has the main disadvantage of not having an activation mechanism that can be quickly activated when the load is li fted by the user .Summary of the invention

[0010] It is therefore a feature of the present invention to provide a robotic device for the passive compensation of an external force that can be activated and deactivated quickly and easily when a load is li fted and when it is released .

[0011] It is also a feature of the present invention to provide such a robotic device that is compact , robust and simple in construction .

[0012] It is also a feature of the present invention to provide an exoskeleton that makes use of such a robotic device .

[0013] These and other obj ects are achieved by a robotic device for the passive compensation of an external force Fext, said robotic device comprising : a frame arranged to define a reference system S having axes x and y lying on a plane 11 ; a first loading arm rotatably connected to said frame by means of a first rotational constraint , said first rotational constraint arranged to allow a relative rotation between said first loading arm and said frame around a rotation axis zxorthogonal to said plane 11, said rotation axis zxintersecting said plane 11 in a rotation center 0 having coordinates x0and y0, said first loading arm comprising a pointlying on said plane 11, the segment 0C1having lengthand forming an anglewith respect to said axis x, said f irst loading arm also comprising a point B±arranged on the segment 0Cl rthe segment 0B1having length b1; an adj ustment element connected to said frame by aconstraint having one degree of freedom, said adj ustment element comprising a point A lying on said plane 11 and having coordinates xAand yA, where 3 / 4 — y0= a, a being an adj ustment parameter ; a first transmission system comprising a first transmission element ; a first elastic element having a first elastic constant k±and arranged to generate a first elastic force Feil, said first elastic element comprising a first end integral with said adj ustment element and a second end connected to said first transmission element at a first end of said first transmission element ; said first transmission system being configured in such a way that , through said first transmission element , said first elastic force Fetlgenerates a first interaction force Fintl=* Fetlacting on said first loading arm, where r±is a first transmission factor, said first interaction force Fintlhaving direction parallel to the segment ABtand passing through said point Bl fwhose main feature is that it is provided an actuator arranged to move said adj ustment element with respect to said frame to vary said coordinate yAand consequently said adj ustment parameter a,and that is also provided a control unit arranged, following an external command, to operate said actuator to move said adj ustment element in order to pass between a first configuration, in which a = al fand a second configuration, in which a = a2, where a±and a2are two determined values of said adj ustment parameter a .

[0014] Advantageously, when an external force Fextparallel to the axis y is applied to the first loading arm at the point C-£ , the external command is arranged to command the actuator to bring the adj ustment element in the second configuration, where a = a2.

[0015] Advantageously, the first transmission system is configured in such a way that the first interaction force Ftnti is directly proportional to the length of the segment ABl fi . e .where c±is a constant value . Therefore , when the adj ustment parameter a and therefore the segment ABtvaries , the first interaction force Fintlvaries in a manner directly proportional to the module of the segment AB±itsel f .

[0016] This way, in the second configuration, to obtain the balance of the external force Fextfor all the possible values of 0-£ ( indi f ferent equilibrium) , must be a2= Fext* ^i / (ci * ^i) •

[0017] In particular, a±= 0. Alternatively, a±is a value such as to compensate for the external moment generated bythe weight of the loading arm when the external force is not applied .

[0018] Advantageously, said first transmission system further comprises : a first deviation pulley which is arranged to rotate around a rotation axis zAorthogonal to said plane 11 and integral with said first adj ustment element , said rotation axis zAintersecting said plane 11 in said point A ; a first attachment pulley arranged to rotate around a rotation axis zB1orthogonal to said plane 11 and integral with said first loading arm, said rotation axis zB1intersecting said plane 11 in said point B±.

[0019] In particular, said first transmission element is a first transmission cable , said first transmission cable comprising a second end integral with said adj ustment element and arranged to wind around said first deviation pulley and said first attachment pulley .

[0020] Advantageously, said first transmission system also comprises a first fastening pulley integral with said adj ustment element , centred in said point A and having a diameter equal to said first attachment pulley . In particular, said second end of said first transmission cable is connected to the outer diameter of said first fastening pulley .

[0021] Advantageously, the following are also provided : a second loading arm rotatably connected to said first loading arm by a second rotational constraint , said second rotational constraint arranged to allow a relative rotation between said second loading arm and said first loading arm around a rotation axi s z2orthogonal to said plane 11, said rotation axis z2intersecting said plane 11 at said point Cl fsaid second loading arm comprising a point C2lying on said plane 11, the segment OC2having length L2and forming an angle 02with respect to said axis x; an mirror loading arm rotatably connected to said frame by a third rotational constraint , said third rotational constraint arranged to allow a relative rotation between said mirror loading arm and said frame around said rotation axis zl fsaid mirror loading arm comprising a point B2, the segment 0B'2having length b2; a second transmission system comprising a second transmission element ; a second elastic element having a second elastic constant k2and arranged to generate a second elastic force Fei2, said second elastic element comprising a first end integral with said adj ustment element and a second end connected to said secondtransmission element at a first end of said first transmission element .

[0022] Advantageously, said second transmission system is configured in such a way that , through said second transmission element , said second elastic force Fei2generates a second interaction force Fint2= r2* Fet2acting on said second loading arm, where r2is a second transmission factor, said second interaction force Fint2having direction parallel to the segment AB2and passing through said point

[0023] In particular, the robotic device is configured in such a way that the segment OB2constantly maintains an angle fl comprised between 0 ° and 10 ° with respect to the segment C1C2.

[0024] In particular, said robotic device is configured in such a way that the segment OB2remains constantly parallel to the segment C1C2, i . e . that is constantly / ? = 0° .

[0025] Advantageously, when an external force Fextparallel to the axis y is applied to the second loading arm at the point C2, the external command is arranged to command the actuator to bring the adj ustment element in the second configuration, where a = a2.

[0026] Advantageously, the second transmission system is configured in such a way that the interaction force Fint2is directly proportional to the length of the segment AB2, i . e .Ptnt2 —c2 * AB2 , where c2is a constant value . Therefore , when the adj ustment parameter a and therefore the segment AB2 varies , the second interaction force Fint2varies in a manner directly proportional to the module of the segment AB2 itsel f .

[0027] This way, in the second configuration, to obtain the balance of the external force Fextfor all the possible values of 0-£ and 02( indi f ferent equilibrium) , both the relationsand a2= Fext* L2 / (c2* ^2) must be satis fied . This is possible by choosing the parameters of the mechanism appropriately in such a way that L1 / (c1* b1) = L2 / (.C2 * ^2) •

[0028] In particular, there

[0029] Advantageously, said second transmission system further comprises : a second deviation pulley arranged to rotate around said rotation axis zA; a second attachment pulley arranged to rotate around a rotation axis zB2orthogonal to said plane 11 and integral with said mirror loading arm, said rotation axis zB2intersecting said plane 11 in said point B2.

[0030] In particular, said second transmission element is a second transmission cable , said second transmission cable comprising a second end integral with said adj ustmentelement and arranged to wind around said second deviation pulley and said second attachment pulley .

[0031] Advantageously, said second transmission system also comprises a second fastening pulley integral with said adj ustment element , centred in said point A and having a diameter equal to said second attachment pulley, and said second end of said second transmission cable is connected to the outer diameter of said second fastening pulley .

[0032] In particular, said external command is provided by a switch operable by a user .

[0033] Alternatively, the external command can be provided by : a voice instruction; a force sensor ; a position sensor ; a timer ; a combination of the above .

[0034] This way, the external command i s provided by the user, or automatically, when the external force Fextparallel to the axis y is applied to the first loading arm at the point Cxor to the second loading arm at the point C2, causing the robotic device to switch to the second configuration and, consequently, balancing the external force with the elastic forces provided by the elastic elements . The external command is then provided again whenthe external force is removed, causing the robotic device to switch to the first configuration .

[0035] Therefore , thanks to the external command, the robotic device produces a passive compensation of the load produced by the external force only when such compensation is required, avoiding that a user has to wear the robotic device already set in the second configuration and therefore has to counteract the elastic force in a muscular way before li fting the load .

[0036] In particular, said adj ustment element is a rotating arm rotatably connected to said frame by a rotational adj usting constraint , said rotational adj usting constraint arranged to allow a relative rotation a between said rotating arm and said frame around a rotation axis xHorthogonal to said plane 11, said rotation axis xHintersecting said plane 11 in a second rotation center H, said point A being located on said rotating arm in such a way that the segment AH forms an angle a with respect to said axis x .

[0037] Advantageously, said actuator is configured to cause the rotation of said rotating arm to vary said angle a, consequently varying said adj ustment parameter a .

[0038] In particular, said first elastic element and / or said second elastic element is a tension spring .

[0039] Alternatively, said first elastic element and / or said second elastic element is a torsional spring .

[0040] According to a further aspect of the invention, an exoskeletal system is claimed comprising : at least one robotic device , according to any of claims from 1 to 9 ; a fastening vest connected to said frame of said or each robotic device ; wherein said first loading arm of said or each robotic device is arranged to be connected to an upper portion of a limb of a user and said second loading arm of said or each robotic device is arranged to be connected to a lower portion of a limb of said user , and wherein said fastening vest is arranged to be connected to the chest of said user .

[0041] This way, the fastening vest allows the load actions produced by the external force to be trans ferred onto the chest of the user .Brief description of the drawings

[0042] The invention will be now shown with the following description of some exemplary embodiments , exempli fying but not limitative , with reference to the attached drawings in which :Fig . 1 shows , in a schematic manner, a possible embodiment of the robotic device , according to thepresent invention, in which only the first loading arm is present;Fig. 2 shows, in a schematic manner, a possible embodiment of the robotic device, according to the present invention, in which only the first loading arm is present;Fig. 3 shows, in a schematic manner, a possible embodiment of the robotic device, according to the present invention, in which the second loading arm is also present;Fig. 4 shows a sectional view of a possible embodiment of the robotic device;Fig. 5 shows a perspective view of a possible embodiment of the robotic device;Fig. 6 shows a sectional view of a possible embodiment of the robotic device, in the first configuration;Fig. 7 shows a sectional view of a possible embodiment of the robotic device, in the second configuration;Figs. 8A and 8B show a side view of a possible embodiment of the robotic device, in the first and second configurations, respectively;Fig. 9 shows a perspective view of a possible embodiment of the fastening vest;Fig. 10 shows a perspective view of a possible embodiment of the exoskeletal device.Description of some preferred exemplary embodiments

[0043] With reference to Figs . 1 , 2 and 3 , the robotic device 100 , according to the present invention, comprises a frame 101 arranged to define a reference system S having axes x and y lying on a plane 11.

[0044] The robotic device 100 then comprises a first loading arm 110 rotatably connected to the frame 101 by means of a first rotational constraint 115 . The first rotational constraint 115 is arranged to allow a relative rotation between the first loading arm 110 and the frame 101 around a rotation axis zxorthogonal to the plane 11. The rotation axis zxintersects the plane 11 in a rotation center 0 having coordinates x0and y0. In particular, the first loading arm 110 comprises a point Cxlying on the plane 11, where the segment 0C1has lengthand forms an anglewith respect to the axis x . The first loading arm 110 also comprises a point B±arranged on the segment OCl fwhere the segment 0B1has length b±.

[0045] The robotic device 100 also comprises an adj ustment element 105 connected to the frame 101 by a constraint having one degree of freedom . In particular, the adj ustment element 105 comprises a point A lying on the plane 11 and having coordinates xAand yA,where a is an adj ustment parameter .

[0046] The robotic device also comprises a first elastic element 130 having a first elastic constant krand arranged to generate a first elastic force Fetl. The first elastic element 130 comprises a first end 131 integral with the adj ustment element 105 .

[0047] Advantageously, the first elastic element 130 is a tension spring .

[0048] Alternatively, the first elastic element 130 is a torsional spring .

[0049] The robotic device 100 then comprises a first transmission system comprising a first transmission element 150 . In the exemplary embodiments of Figs . 1 , 2 and 3 , the first transmission element 150 is a transmission cable 150 .

[0050] Furthermore , the first transmission system comprises a first deviation pulley 156 arranged to rotate around a rotation axis zAorthogonal to the plane 11 and integral with the first adj ustment element 105 , where the rotation axis zAintersects the plane 11 in the point A, and a first attachment pulley 157 arranged to rotate around a rotation axis zB1orthogonal to the plane 11 and integral with the first loading arm 110 , where the rotation axis zB1intersects the plane 11 in the point B±.

[0051] In particular, both the first deviation pulley 156 that the first attachment pulley 157 are idler pulleys .

[0052] Alternatively, the pulleys 156 and 157 can be replaced by low- friction pins .

[0053] Advantageously, the first transmission system also comprises a first fastening pulley 158 integral with the adj ustment element 105 , centred in the point A and having a diameter equal to the first attachment pulley 157 .

[0054] The first transmission cable 150 comprises a first end 151 connected to the second end of the first elastic element 130 and a second end 152 connected to the outer diameter of the first fastening pulley 158 .

[0055] In particular, the first transmission cable is arranged to wind around the first deviation pulley 156 and the first attachment pulley 157 .

[0056] This way, the first transmission system is configured in such a way that , through the first transmission element 150 , the first elastic force Feilgenerates a first interaction force Fintl= r±* Fetlacting on the first loading arm 110 , where r±is a first transmission factor, where the first interaction force Fintlhas direction parallel to the segment ABtand passing through the point Bi .

[0057] In the embodiments shown in Figs . 1 and 2 , the first transmission factor r±is equal to 2 . Increasing the windings of the transmission cable 150 on the pulleys 156 and 157 it is possible to increase this factor .

[0058] Furthermore , the robotic device 100 comprises an actuator 170 arranged to move the adj ustment element 105 with respect to the frame 101 to vary the coordinate yAand consequently the adj ustment parameter a .

[0059] The robotic device 100 then comprises a control unit arranged, following an external command, to operate the actuator 170 to move the adj ustment element 105 in order to pass between a first configuration, in which a = al fand a second configuration, in which a = a2, where a±and a2are two determined values of the adj ustment parameter a .

[0060] Advantageously, when an external force Fextparallel to the axis y is applied to the first loading arm 110 at the point Cx, the external command is arranged to command the actuator 170 to bring the adj ustment element 105 in the second configuration, where a = a2.

[0061] Advantageously, the first transmission system is configured in such a way that the first interaction force Ftnti is directly proportional to the length of the segment ABl fi . e .where c±is a constant value . Therefore , when the adj ustment parameter a and therefore the segment ABtvaries , the first interaction force Fintlvaries in a manner directly proportional to the module of the segment AB±itsel f .

[0062] This way, in the second configuration, to obtain the balance of the external force Fextfor all the possiblevalues of 0-£ ( indi f ferent equilibrium) , must be a2= Fext* ^i / (ci * ^i) •

[0063] In the embodiment of Fig . 1 , the adj ustment element 105 is a mobile arm arranged to translate along the axis y as a result of the movement of the actuator 170 , thus varying the adj ustment parameter a .

[0064] In the embodiment of Fig . 2 , the adj ustment element 105 is a rotating arm 105 rotatably connected to the frame 101 by a rotational adj usting constraint 106 . The rotational adj usting constraint 106 is arranged to allow a relative rotation a between the rotating arm 105 and the frame 101 around a rotation axis xHorthogonal to the plane 11, where the rotation axis xHintersects the plane 11 in a second rotation center H, and where the point A is located on the rotating arm 105 in such a way that the segment AH forms an angle a with respect to the axis x .

[0065] With reference to Fig . 3 , in a preferred embodiment , the robotic device 100 also comprises a second loading arm 120 rotatably connected to the first loading arm 110 by a second rotational constraint 125 . The second rotational constraint 125 is arranged to allow a relative rotation between the second loading arm 120 and the first loading arm 110 around a rotation axis z2orthogonal to the plane 11, where the rotation axis z2intersects the plane 11 at the point C1. The second loading arm 120 comprises a point C2lying on the plane 11, where the segment OC2has length L2and forms an angle 02with respect to the axis x .

[0066] The robotic device also comprises a mirror loading arm 120 ' rotatably connected to the frame 101 by a third rotational constraint 135 . The third rotational constraint 135 is arranged to allow a relative rotation between the mirror loading arm 120 ' and the frame 101 around its rotation axis z±. The mirror loading arm 120 ' comprises a point B2, such that the segment OB'2has length b2.

[0067] The robotic device also comprises a second elastic element 140 having a second elastic constant k2and arranged to generate a second elastic force Fet2. The second elastic element 140 comprises a first end 141 integral with the rotating arm 105 .

[0068] Advantageously, the second elastic element 140 is a tension spring .

[0069] Alternatively, the second elastic element 140 is a torsional spring .

[0070] The robotic device 100 then comprises a second transmission system comprising a second transmission cable 160 .

[0071] Furthermore , the second transmission system comprises a second deviation pulley 166 arranged to rotate around its rotation axis zAand a second attachment pulley 167 arranged to rotate around a rotation axis zB2orthogonalto the plane 11 and integral with the mirror loading arm120 ' , where the rotation axis zB2intersects the plane 11 in the point B2.

[0072] In particular, both the second deviation pulley 166 and the second attachment pulley 167 are idler pulleys .

[0073] Alternatively, the pulleys 166 and 167 can be replaced by low- friction pins .

[0074] Advantageously, the second transmission system also comprises a second fastening pulley 168 integral with the rotating arm 105 , centred in the point A and having a diameter equal to the second attachment pulley 167 .

[0075] The second transmission cable 160 comprises a first end 161 connected to the second end of the second elastic element 140 and a second end 162 connected to the outer diameter of the second fastening pulley 168 .

[0076] In particular, the second transmission cable is arranged to wind around the second deviation pulley 166 and the second attachment pulley 167 .

[0077] This way, the second transmission system is configured in such a way that , through the second transmission element 160 , the second elastic force Fei2generates a second interaction force Fint2= r2* Fet2acting on the second loading arm 120 , where r2is a second transmission factor, where the second interaction force Fint2hasdirection parallel to the segment AB2and passing through the point B2.

[0078] In the embodiments shown in Figs . 1 and 2 , the second transmission factor r2is equal to 2 . Increasing the windings of the transmission cable 160 on the pulleys 166 and 167 it is possible to increase this factor .

[0079] In particular, the robotic device 100 is configured in such a way that the segment OB2constantly maintains an angle fl comprised between 0 ° and 10 ° with respect to the segment C1C2.

[0080] Furthermore , the robotic device 100 is configured in such a way that the segment OB2remains constantly parallel to the segmenti . e . that is constantly / ? = 0° .

[0081] In particular, to achieve parallelism between the segment OB2and the segment C1C2, an auxiliary arm may be provided hinged to the mirror loading arm 120 ' at the point B2and to the second loading arm 120 at a point B2such that the segment C1B2has length b2. This way, the mirror loading arm 120 ' , the first loading arm 110 , the second loading arm 120 and the auxiliary arm form an articulated quadrilateral .

[0082] Alternatively, the parallelism between the segment OB2and the segment C±C2can be achieved by means of a system of pulleys and cables , as shown in Figs . 8A and 8B .

[0083] Advantageously, when an external force Fextparallel to the axis y is applied to the second loading arm 120 atthe point C2, the external command is arranged to command the actuator 170 to bring the adjustment element 105 in the second configuration, where a = a2.

[0084] Advantageously, the second transmission system is configured in such a way that the interaction force Fjnt2is directly proportional to the length of the segment AB2, i.e. Ptnt2= c2 * AB2, where c2is a constant value. Therefore, when the adjustment parameter a and therefore of the segment AB2varies, the second interaction force Fint2varies in a manner directly proportional to the module of the segment AB2itself .

[0085] This way, in the second configuration, to obtain the balance of the external force Fextfor all the possible values of 0-£ and 02(indifferent equilibrium) , both the relationsmust be satisfied. This is possible by choosing the parameters of the mechanism appropriately in such a way that L1 / (c1*b1) = L2 / (.C2 * b2) .

[0086] Figs. 4 and 5 show a section of a possible application of the robotic device 100, in which the two elastic elements 130 and 140 are visible, both made with torsional springs. In Fig. 5, it is possible to see the pulley 135 that transforms the elastic torque of the torsional spring 130 into an elastic force Feil.

[0087] Figs . 6 and 7 show an applicative embodiment of the robotic device 100 comprising the first loading arm 110 , in the first and second configurations , respectively .

[0088] Figs . 6 and 7 show an applicative embodiment of the robotic device 100 comprising both the first loading arm 110 and the second loading arm 120 , in the first and second configurations , respectively .

[0089] With reference to Figs . 9 and 10 , the present invention also claims an exoskeletal system 10 comprising two robotic devices 100 and a fastening vest 200 .

[0090] In particular, the robotic devices 100 are connected to the fastening vest 200 by the connection of the elements 205 and 204 , arranged to provide two rotational constraints .

[0091] In particular, the first loading arm 110 and the second loading arm 120 of each robotic device 100 are arranged to be connected, respectively, to an upper portion and to a lower portion of a limb of a user, whereas the fastening vest 200 is arranged to be connected to the chest of the user to trans fer the loading actions produced by the external force onto the chest of the user itsel f .

[0092] In particular, the exoskeletal system also comprises a switch arranged to provide the external command . For example , this switch can be a sensori zed thimble wearable by the user .

[0093] This way, when the user holds a load, having a weight force equal to the external force Fext, the external command can be easily activated, even with the hands busy, by switching the robotic device into the second configuration and, consequently, balancing the external force with the elastic forces provided by the elastic elements . The external command is then provided again when the external force is removed, i . e . the load is released, by switching the robotic device into the first configuration .

[0094] Therefore , thanks to the external command, the robotic device produces a passive compensation of the load produced by the external force only when such compensation is required, avoiding that a user has to wear the robotic device already set in the second configuration and therefore has to counteract the elastic force in a muscular way before li fting the load . This operation i s completely analogous in the case that the external command is provided via a voice command or other system that allows the user to provide such command while his hands are busy grasping the load .

[0095] The foregoing description exemplary embodiments of the invention will so fully reveal the invention according to the conceptual point of view, so that others , by applying current knowledge , will be able to modi fy and / or adapt for various applications such embodiment without furtherresearch and without parting from the invention, and, accordingly, it is therefore to be understood that such adaptations and modi fications will have to be considered as equivalent to the speci fic embodiments . The means and the materials to realise the di f ferent functions described herein could have a di f ferent nature without , for this reason, departing from the field of the invention . It is to be understood that the phraseology or terminology that is employed herein is for the purpose of description and not of limitation .

Claims

CLAIMS1. A robotic device (100) for the passive compensation of an external force Fext, said robotic device (100) comprising : a frame (101) arranged to define a reference system S having axes x and y lying on a plane 11; a first loading arm (110) rotatably connected to said frame (101) by means of a first rotational constraint (115) , said first rotational constraint (115) arranged to allow a relative rotation between said first loading arm (110) and said frame (101) around a rotation axis zxorthogonal to said plane 11, said rotation axis zxintersecting said plane 11 in a rotation center 0 having coordinates x0and y0, said first loading arm (110) comprising a point C-£ lying on said plane 11, the segment 0C1having lengthand forming an anglewith respect to said axis x, said first loading arm (110) also comprising a point B±arranged on the segment OClfthe segment 0B1having length b1; an adjustment element (105) connected to said frame (101) by a constraint having one degree of freedom, said adjustment element (105) comprising a point A lying on said plane 11 and having coordinates xAand yA, where — yo= a>abeing an adjustmentparameter; a first transmission system comprising a first transmission element (150) ; a first elastic element (130) having a first elastic constant k±and arranged to generate a first elastic force Feii, said first elastic element (130) comprising a first end (131) integral with said adjustment element (105) and a second end (132) connected to said first transmission element (150) at a first end (151) of said first transmission element ( 150 ) ; an actuator (170) arranged to move said adjustment element (105) with respect to said frame (101) to vary said coordinate yAand consequently said adjustment parameter a; a control unit arranged, following an external command, to operate said actuator (170) to move said adjustment element (105) in order to pass between a first configuration, in which a = a,i, and a second configuration, in which a = a2, where arand a2are two determined values of said adjustment parameter a; said first transmission system being configured in such a way that, through said first transmission element (150) , said first elastic force Fen generates a firstinteraction force Fintl= rr* Fe(1acting on said first loading arm (110) , where r±is a first transmission factor, said first interaction force Ftnti having direction parallel to the segment ABtand passing through said point Blfsaid robotic device (100) characterized in that said first transmission system is also configured in such a way that said first interaction force Fintlis directly proportional to the length of the segment ABlfnamelywhere c±is a constant value.

2. The robotic device (100) , according to claim 1, wherein said first transmission system further comprises: a first deviation pulley (156) arranged to rotate around a rotation axis zAorthogonal to said plane 11 and integral with said first adjustment element (105) , said rotation axis zAintersecting said plane 11 in said point A; a first attachment pulley (157) arranged to rotate around a rotation axis zB1orthogonal to said plane 11 and integral with said first loading arm (110) , said rotation axis zB1intersecting said plane 11 in said point B1; and wherein said first transmission element (150) is a first transmission cable (150) , said first transmission cable (150) comprising a second end (152) integral withsaid adjustment element (105) and arranged to wind around said first deviation pulley (156) and said first attachment pulley (157) .

3. The robotic device (100) , according to claim 2, wherein said first transmission system also comprises a first fastening pulley (158) integral with said adjustment element (105) , centred in said point A and having a diameter equal to said first attachment pulley (157) , and wherein said second end (152) of said first transmission cable (150) is connected to the outer diameter of said first fastening pulley (158) .

4. The robotic device (100) , according to claim 1, wherein the following are also provided: a second loading arm (120) rotatably connected to said first loading arm (110) by a second rotational constraint (125) , said second rotational constraint (125) arranged to allow a relative rotation between said second loading arm (120) and said first loading arm (110) around a rotation axis z2orthogonal to said plane 11, said rotation axis z2intersecting said plane 11 at said point Clfsaid second loading arm (120) comprising a point C2lying on said plane 11, the segment OC2having length L2and forming an angle 02with respect to said axis x; a mirror loading arm ( 120 ’ ) rotatably connected tosaid frame (101) by a third rotational constraint (135) , said third rotational constraint (135) arranged to allow a relative rotation between said mirror loading arm ( 120 ’ ) and said frame (101) around said rotation axissaid mirror loading arm ( 120 ’ ) comprising a point B2, the segment OB2having length b2; a second transmission system comprising a second transmission element (160) ; a second elastic element (140) having a second elastic constant k2and arranged to generate a second elastic force Fei2r said second elastic element (140) comprising a first end (141) integral with said adjustment element (105) and a second end (142) connected to said second transmission element (160) at a first end (161) of said first transmission element (160) ; said second transmission system being configured in such a way that, through said second transmission element (160) , said second elastic force Fet2generates a second interaction force Fint2= r2* Fet2acting on said second loading arm (120) , where r2is a second transmission factor, said second interaction force Fint2having direction parallel to the segment AB2and passing through said point B2,said robotic device (100) being configured in such a way that the segment OB2constantly maintains an angle P comprised between 0° and 10° with respect to the segment C1C2.

5. The robotic device (100) , according to claim 4, wherein said second transmission system further comprises: a second deviation pulley (166) arranged to rotate around said rotation axis zA; a second attachment pulley (167) arranged to rotate around a rotation axis zB2orthogonal to said plane 11 and integral with said mirror loading arm (120' ) , said rotation axis zB2intersecting said plane 11 in said point B2; and wherein said second transmission element (160) is a second transmission cable (160) , said second transmission cable (160) comprising a second end (162) integral with said adjustment element (105) and arranged to wind around said second deviation pulley (166) and said second attachment pulley (167) .

6. The robotic device (100) , according to claim 5, wherein said second transmission system also comprises a second fastening pulley (168) integral with said adjustment element (105) , centred in said point A and having a diameter equal to said second attachment pulley (167) , and wherein said second end (162) of said secondtransmission cable (160) is connected to the outer diameter of said second fastening pulley (168) .

7. The robotic device (100) , according to any of the previous claims, wherein said external command is provided by a switch operable by a user.

8. The robotic device (100) , according to any of the previous claims, wherein said adjustment element (105) is a rotating arm (105) rotatably connected to said frame (101) by a rotational adjusting constraint (106) , said rotational adjusting constraint (106) arranged to allow a relative rotation a between said rotating arm (105) and said frame (101) around a rotation axis xHorthogonal to said plane 11, said rotation axis xHintersecting said plane 11 in a second rotation center H, said point A being located on said rotating arm (105) in such a way that the segment AH forms an angle a with respect to said axis x.

9. The robotic device (100) , according to claim 8, wherein said actuator (170) is configured to cause the rotation of said rotating arm (105) to vary said angle a, consequently varying said adjustment parameter a.

10. An exoskeletal system (10) comprising: at least one robotic device (100) , according to any of claims from 1 to 9;a fastening vest (200) connected to said frame (101) of said or each robotic device (100) ; wherein said first loading arm (110) of said or each robotic device (100) is arranged to be connected to an upper portion of a limb of a user and said second loading arm (120) of said or each robotic device (100) is arranged to be connected to a lower portion of a limb of said user, and wherein said fastening vest (200) is arranged to be connected to the chest of said user.

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