TECHNICAL FIELD

[001]. The object of the present invention is an exoskeleton.

[002]. In particular, the exoskeleton according to the invention comprises a knee junction.

BACKGROUND ART

[003]. Wearable exoskeletons for supporting the weight of a user as well as adapted to assist the user in lifting and transporting loads even over long distances are generally used in various fields, such as in the military field as well as in the field of rehabilitation, in explorations and excursions, as well as in the field of construction/demolition.

[004]. With particular reference to the military and defence field, it is common to equip soldiers in the field with wearable exoskeletons to redirect the load carried by the soldier on the ground, as well as exoskeletons for special operating forces and police officers in riot gear have been proposed.

[005]. The known wearable exoskeleton solutions can include active parts, i.e., motorized to assist the structural functions, which require the integration of a dedicated power supply system (for example portable batteries) which entails, beyond an additional weight, the risk of malfunctions, even sudden, moreover in very critical scenarios, for example due to a low power or defective battery condition.

[006]. Otherwise, passive wearable exoskeletons have been proposed, freed from the need for electrical power supply.

[007], Some known examples of passive exoskeletons are made of titanium, steel, or carbon fibre and typically comprise a backbone element for protecting the user's spine, which extends from a belt to the shoulders of the exoskeleton, and articulated elements which extend between the belt and the ground for transferring the load to the ground.

[008]. Such articulated elements for transferring load to the ground usually extend around the lower limbs (legs) of the user and comprise a thigh portion, articulated to the belt, and a tibial portion to protect the calf which is in turn articulated to a lower end of the thigh portion. In particular, a joint is provided between the thigh portion and the tibial portion of the exoskeleton to protect the user's knee articulation. A further junction is provided below to protect the user's ankle, between the tibial element and a further element.

[009]. It is known to make the rotational joint between the thigh element and the tibial element of the exoskeleton by means of a simple hinge. However, this solution, although in part advantageous for simplicity of implementation, is not lacking drawbacks, which derive from the fact that the articulation of the human knee (and thus of the user) is not, from a kinematic point of view, a simple hinge (in flexionextension). This necessarily generates imbalances when in operating conditions and can result in discomfort for the user because the load transmission line is altered.

[010]. Furthermore, the known solutions of exoskeletons of the aforementioned type prevent the rotation of the knee, i.e., the relative rotation between fibula and tibia, in the adduction-abduction direction.

[011]. In addition to the above, the human knee also comprises torsional mobility, i.e., relative adduction/abduction rotations of the tibia and fibula (shin).

[012]. In addition, human body types have various knee morphotypes, in particular defining genu varum when the femur and tibia are not perfectly aligned, forming an inward angle, and genu valgum when the angle opens outwards.

[013]. On the other hand, as is generally known from biomechanics, the knee can be assimilated in flexion-extension to a condyloid joint, i.e., a joint formed by rounded bone prominence which is inserted in the cavity of another bone (femur and tibia), with which it articulates. The cruciate ligaments of the human knee form, along with the femur and tibia, an articulated quadrilateral. Such cruciate ligaments are not rigid structures, but can undergo elongation under physiological conditions of load. The knee, in addition to the complex anatomy of the articular surfaces, comprises other structures such as the menisci and patella, which allow stabilization, friction reduction, and load transmission. During flexion and extension, the tibia rolls and slides on the femur, causing a displacement of the instantaneous rotation axis of about 20-30 mm.

[014]. In some well-known biomechanical models of the knee articulation, the kinematic concept of conjugate profiles is used, i.e., two curves in the plane which are in contact at one point and have the tangent in common in that point. Such conjugate profiles are connected to each other by means of the cruciate ligaments. It is precisely these ligaments which determine the kinematics and the type of rotation of the tibia with respect to the femur. Thus, the contact surfaces (conjugate profiles) support the load and the ligaments determine and limit the motion.

[015]. Therefore, in the known exoskeletons, the articulation between the thigh element and the tibial element is typically implemented by a crossed articulated quadrilateral kinematic mechanism, in which the crossed elements (e.g., plates) create the cruciate ligaments in the exoskeleton.

[016]. However, this type of solution requires the creation of complex mechanisms which typically envisage sliding, i.e., the translation of the articulation pin in the respective elongated or arcuate or cammed hole, when in operating conditions.

[017]. Furthermore, it should be noted that while the cruciate ligaments are structures capable of extending, i.e., deforming in a recoverable manner when in operating conditions, the crossed rods of the exoskeleton are rigid (in steel, for example).

[018]. In addition, exoskeletons of the type described above require a dedicated design for each individual user, because the biomechanical features of the knees of various users are highly variable. To this end, solutions have been proposed which envisage a preparatory scan (for example computerized tomography) of the user's body for sizing the exoskeleton, but this involves excessive costs and time, whereby it does not fully solve the problem.

[019]. The need is therefore strongly felt to provide an exoskeleton solution provided with an improved knee junction, which is compatible with various body types while being suitable for large-scale production.

SUMMARY OF THE INVENTION

[020]. It is an object of the present invention to overcome the drawbacks lamented with reference to the background art.

[021]. These and other objects are achieved by an exoskeleton according to claim 1 .

[022]. Some advantageous embodiments are the object of the dependent claims.

[023]. Thanks to the proposed solutions, it allows to make a knee junction of an exoskeleton by means of a hinge with a double axis of rotation. [024], It is thus avoided to provide a knee junction with a crossed articulated quadrilateral connection.

[025], Thanks to the proposed solutions, the knee junction of the exoskeleton can be made in a simple and at the same time reliable manner.

[026]. Thanks to the proposed solutions, a light and at the same time robust and resistant exoskeleton which is also simple to manufacture can be made.

BRIEF DESCRIPTION OF THE FIGURES

[027], Further features and advantages of the invention will appear from the following description of embodiments, given by way of non-limiting example, with reference to the accompanying figures, in which:

- figure 1 is an axonometric front view of an exoskeleton, according to an embodiment;

- figure 2 is an axonometric rear view of the exoskeleton of figure 1 ;

- figure 3 is a vertical raised view of a portion of an exoskeleton, according to an embodiment, with the knee extended;

- figure 4 is a cross section made according to the cutting plane indicated by the arrows B-B in figure 3;

- figure 5 is an axonometric view showing a portion of an exoskeleton, according to an embodiment, with the knee flexed;

- figure 6 is an axonometric view of a portion of an exoskeleton, according to an embodiment, in which some parts are illustrated in exploded view;

- figure 7 shows a rear axonometric view of a portion of an exoskeleton, according to an embodiment, with the knee extended;

- figure 8 shows an exoskeleton frontally, according to an embodiment, worn by a user.

DETAILED DESCRIPTION OF SOME PREFERRED EMBODIMENTS

[028]. In accordance with a general embodiment, an exoskeleton 10 is provided.

[029]. The exoskeleton 10 is a wearable exoskeleton, adapted to be worn by a user U, as shown for example in figure 8. [030]. In accordance with a preferred embodiment, the exoskeleton 10 is adapted to form a path of forces such as to support the user in transporting loads to protect the user's articulations from excessive stresses.

[031]. The exoskeleton 10 can find application in the military field and can comprise suitable protective devices for such a purpose.

[032]. The exoskeleton 10 comprises at least one leg assembly 12L, 12R having an upper portion 15 (or thigh portion 15, or thigh support 15) and a lower portion 16 (or shin support 16).

[033]. The terminology "leg assembly 12L, 12R" used is not intended to indicate that the exoskeleton 10 must comprise elements which extend for the entire extension of the leg of the user U, although, in accordance with a preferred embodiment, the leg assembly 12L, 12R extends from the belt 11 to the foot 27 or bracket 27 of the exoskeleton. Therefore, the term "leg assembly" is also intended to indicate a "knee brace assembly", and in this case the exoskeleton can only be formed by said knee brace assembly 12L, 12R.

[034], In accordance with a preferred embodiment, as shown for example in figures 1 and 2, the exoskeleton 10 comprises a belt 11 and two leg assemblies (in particular: a right leg assembly 12R and a left leg assembly 12L) both articulated to the belt 11. The belt 11 can comprise further junctions connecting portions of the exoskeleton 10 to the back and shoulders of the user.

[035]. The at least one leg assembly 12L, 12R can be designed to determine a path of strengths such as to avoid over-stressing the user's knee articulation.

[036]. Between the thigh portion 15 and the shin support 16, the at least one leg assembly 12L, 12R comprises a knee joint KJ. The knee joint KJ forms the knee articulation of the leg assembly 12L, 12R of the exoskeleton 10.

[037], In accordance with an embodiment, the wearable exoskeleton 10 is substantially a knee brace-exoskeleton 10, which extends, when in operating conditions, around the user's knee.

[038]. The knee joint KJ of the exoskeleton 10 is formed by a hinge with a double centre of rotation 20.

[039]. The centres of rotation of the hinge 20 are preferably formed by mutually parallel and dislocated axes X1 , X2, i.e., spaced along the leg assembly 12L, 12R to form the knee joint KJ of the exoskeleton 10.

[040]. Preferably, in each leg assembly 12L or 12R it is possible to define an inner side 13 of the knee joint KJ which is facing the other leg assembly 12R or 12L, and an opposite, outer side 14 of the knee joint KJ which is facing opposite with respect to the inner side 13. In accordance with an embodiment, therefore, the knee joint KJ comprises an inner side 13 and an outer side 14.

[041]. The double centre of rotation hinge 20 forming the knee junction KJ of the leg assembly 12L, 12R extends on both the inner side 13 and the outer side 14. Preferably, in such a case, the inner side 13 of the double centre of rotation hinge 20 of the knee joint KJ comprises its articulation holes 33, and also the outer side 14 comprising its articulation holes 34, said articulation holes 33, 34 being coaxial two-by-two. In other words, each articulation hole 33 of the inner side 13 is coaxial with an articulation hole 34 of the outer side 14. It thereby becomes possible to make a double centre of rotation hinge 20 on the inner side 13 and on the outer side 14. In other words, also in this embodiment which provides the coaxial holes 33, 34 two-by-two on two branches (inner and outer) of the hinge 20 configured to deliver a coordinated action when in use, there are two centres of rotation (axes X1 and X2) of the hinge 20 of the knee articulation KJ.

[042], Where two leg assemblies 12L, 12R are provided each having knee joint KJ formed by a double axis of rotation hinge 20 thereof, the centres of rotation can all be aligned with each other.

[043], The knee joint KJ comprises a rigid connecting portion 18 extending between the inner side 13 and the outer side 14 and is thus articulated to the thigh portion 15 with a single degree of freedom of rotation around a first axis X1 , said rigid connecting portion 18 also being articulated to the shin support 16 with a single degree of freedom of rotation around a second axis X2. The axes X1 , X2 are preferably parallel, thereby forming the double centre of rotation hinge 20 of the knee articulation KJ of the exoskeleton 10.

[044]. Advantageously, the rigid connecting portion 18 is a knee brace 18 for protecting the patella and the front part of the knee.

[045]. Therefore, the kinematic mechanism of the knee joint KJ of the exoskeleton 10 is simplified with respect to the biomechanics of the human knee, however, this still allows the exoskeleton 10 to be worn and used sufficiently comfortably, maximizing the operating duration of the knee junctions KJ of the exoskeleton.

[046]. Thanks to the use of said double centre of rotation hinge 20 to make the knee joint KJ of the exoskeleton 10, a kinematically simplified solution is provided, with respect to the known solutions of crossed articulated quadrilateral knee joint, thus simpler to manufacture, although equally efficient and reliable when in use.

[047], This thus avoids the need to make knee joints based on crossed quadrilateral mechanisms.

[048]. The provision of such a knee joint KJ formed by a hinge with a double centre of rotation 20 avoids having to make oblong and/or arcuate and/or cammed holes, as is instead typical in the well- known cases of knee joints made by means of crossed articulated quadrilateral mechanisms.

[049]. In accordance with an embodiment, the thigh portion 15 of the at least one leg assembly 12L, 12R is articulated to the belt 11 on the outer side of the belt 11. It is well understood that the term "inner/outer side" is intended to mean, by extension, also the inner side of other parts of the leg assembly 12L, 12R, although the exoskeleton 10 does not necessarily comprise material on the inner/outer side.

[050]. As mentioned above, the thigh portion 15 can be articulated to the belt 11 and can comprise an elongated body element 30 which extends along the outer side of the double centre of rotation hinge 20 forming in a single piece also a portion on the inner side 14 of said double centre of rotation hinge 20. In other words, preferably, the thigh portion 15 comprises a distal portion 28 thereof which forms a part of the knee junction KJ, i.e., of the double centre of rotation hinge 20. Said distal portion 28 of the thigh support 15 preferably has a curved body extending frontally towards the inner side 13 to contour the user's anatomy (leg area which laps the patella above).

[051]. Preferably, therefore, the elongated body element 30 of the thigh support 15 extends substantially vertically on the outer side of the leg assembly 12L, 12R to articulate to the belt 11 , forming a hip joint HJ.

[052], The elongated element 30 can comprise include an adjustment mechanism 32, for example to adjust the distance between the belt 11 and the double centre of rotation hinge 20 of the knee joint KJ, which can comprise a raised graduated profile (e.g., adjustment notches). In other words, said elongated body element 30 is preferably adapted to form a slider 30 for a vertical adjustment mechanism 32 of the thigh support 15, which, for example, slidably engages a loop provided on the same thigh support 15. The loop of the thigh support 15 can in turn comprise in a single piece a portion to embrace part of the thigh of the user U.

[053]. A vertical adjustment mechanism 32, similar to or different from that of the thigh support

15, can be provided on the shin support 16.

[054]. The at least one leg assembly 12L, 12R can further comprise a foot portion 27, for example comprising a bracket 27, which can be articulated below the shin support 16. Preferably, the foot portion 27 comprises at least one surface in contact with the ground for discharging loads to the ground, and even more preferably the foot portion 27 has a bracket 27 comprising two branches or arms, i.e., it bifurcates, forming an inner arm on the inner side and an outer arm on the outer side towards the ground. A further articulation can be provided between the foot bracket and the contact portion to allow dorsal and plantar flexion movement of the foot of the user U.

[055]. Preferably, and as shown for example in figure 3, the double centre of rotation hinge 20 comprises a rigid element 19, for example a plate, which extends from the thigh portion 15 to the shin support 16. The rigid element 19 of the hinge 20 forms a first rotational joint 21 , for example a pin joint with the thigh portion 15 and a second rotational joint 22, for example also a pin joint, with the shin portion

16.

[056]. Thanks to the provision of the double centre of rotation hinge 20, the instantaneous centre of rotation between the shin portion 16 and the thigh portion 15 is always on the straight segment joining the first rotational joint 21 (axis X1) and the second rotational joint 22 (axis X2), when in flexo- extension FL-EX operating conditions.

[057], The double centre of rotation hinge 20 in bent knees conditions can be arranged so that the transfer of the load between the two joints 21 , 22 occurs, by means of the rigid element 19, substantially vertically to be discharged even partially to the ground by means of the front wall 31 of the shin support, i.e., being able to assume a configuration similar to that shown in figure 5 with a bent knee.

[058]. Where the hinge 20 extends on the inner side 13 and on the outer side 14 of the knee joint KJ, a single rigid element 19 can be provided, i.e., the rigid element 19 of the inner side 13 can be in a single piece with the rigid element of the outer side 14 of the same double centre of rotation hinge 20. [059]. Where the hinge 20 extends on the inner side 13 and on the outer side 14 of the knee joint KJ, the shin support 16 can comprise a body extending substantially frontally along the leg assembly 12L; 12R, forming in a single piece a portion on the inner side 13 and a portion on the outer side 14 of the knee articulation KJ, substantially forming a "T"-shaped structure similar to the user's anatomical tibia.

[060]. Therefore, where the hinge 20 extends on the inner side 13 and on the outer side 14 of the knee joint KJ, the relative configurations between the upper rotational joints 21 and the relative configurations between the lower rotational joints 22 of the hinge 20 are rigidly determined by the body of the distal portion 28 of the thigh support 15 and the body of the connecting portion 24 of the shin support 16, respectively.

[061]. In accordance with a preferred embodiment, the rigid element 19 of the double centre of rotation hinge 20 further comprises, in a single piece, the knee brace 18, to protect the user's patella. Therefore, a single piece can be provided, for example substantially in the form of a shell or cap, which defines a housing for the user's knee and at the same time the centres of rotation of the double centre of rotation hinge of the knee joint KJ of the exoskeleton 10.

[062]. Padding 17 can be provided on the rigid element 19 and/or on the rotational joints 21 , 22, e.g., of the pin type. The padded knee brace can comprise at least one padding layer 17 having a thickness of 5-25 millimetres, for example 10-15 millimetres, which can be configured in separate islands, as shown, for example, in figure 7. For example, padding islands 17 are glued or otherwise fixed to various portions of the knee joint KJ of the exoskeleton which are intended to come into contact with the user's knee when the user wears the exoskeleton 10. Therefore, padding 17 can be provided on the userfacing face of the rigid element 19 and/or of the rotational joints 21 , 22 and/or of the connecting portion 24 of the shin support 16 and/or of the distal portion 28 of the thigh support 15. On the opposite face of the knee brace 18, i.e. ,the front-facing face, a surface processing can be provided which can comprise grooves and/or punch marks, for example an anti-slip and/or anti-impact machining.

[063]. The profiles of the pieces forming the knee joint KJ of the exoskeleton 10 can be variously shaped to perform both an optimized load transfer function which excludes the knee articulation of the user, even in bent knee conditions, and a protection function, at least frontal, from impacts or shocks. [064]. Lightening openings can be provided on the parts forming the knee joint KJ of the exoskeleton 10.

[065]. In accordance with a preferred embodiment, the pieces forming the knee joint KJ of the exoskeleton 10 are made of polymeric material and/or polymer matrix composite material. For example, Nylon PA12-type polymer is used. It is thereby possible to make a knee junction KJ which is robust and at the same time light, low-cost to produce and simple to manufacture. For example, the pieces are manufactured by means of moulding. The pins, even threaded if necessary i.e., tapped, of the double centre of rotation hinge 20 can be made of metal.

[066]. In accordance with a preferred embodiment, the knee brace 18 comprises an abutment surface 36 for a respective abutment counter-surface 38 of the shin support 16, which acts as an extension limit switch for the knee articulation KJ of the exoskeleton 10. In other words, the extension limit switch abutment can be formed by the profiles, suitably shaped, of the knee brace 18 and of the connecting portion 24 of the shin support 16.

[067]. Alternatively or additionally, the abutment surface 36 of the knee brace 18 and the respective abutment counter-surface 38 of the shin support 16 comprise a profile shaped in a coordinated manner, so as to be in close contact with each other at the limit switch for a transverse front section which extends, seamlessly, from the inner side 13 to the outer side 14 of the knee joint KJ. Thereby, a further at least frontal and preferably also lateral protection (inner and outer side) for the user's knee is obtained.

[068]. The knee brace 18 can further comprise an abutment surface 35 for a respective abutment counter-surface 37 of the thigh portion 15 which acts as an extension limit switch for the knee articulation KJ of the exoskeleton 10. In other words, the extension limit switch abutment can be formed by the profiles, suitably shaped, of the knee brace 18 and of the distal portion 28 of the thigh support 15.

[069]. The lower portion 16 or shin support 16 of the leg assembly 12L, 12R can comprise a front protrusion 31 extending upwards, i.e., toward the thigh portion 15, and abutting a seat or recess of the knee brace 18 having a concavity facing substantially downwards, i.e., towards the foot portion 27 of the exoskeleton 10. The front protrusion 31 of the upper connecting portion of the shin support 16 can also perform a protective function for the knee of the user U, for example it can form the support surface for the user when in a folded position, i.e., with the knee flexed and resting with the upper shin support on the ground.

[070], In accordance with to an embodiment, as shown for example in figure 6, the shin support 16 further comprises an adjustment mechanism 23 for adjusting the orientation of the shin support with respect to the thigh portion 15. Preferably, the adjustment mechanism 23 acts on a degree of freedom inside the shin support 16, to adjust the orientation in the inner/outer direction IN-OUT, i.e., adductionabduction, i.e., in other words, the adjustment mechanism 23 is for adjusting the camber of the shin support. The adjustment mechanism 23 can be designed to be accessible to a user U wearing the exoskeleton.

[071]. Therefore, the shin support 16 can comprise a connecting portion 24 which is proximal, i.e., upper when in use, comprising at least one centre of rotation 22 of the double centre of rotation hinge 20 of the knee joint KJ, and a shin guard portion 25 which is distal, i.e., lower than the connecting portion 24, and in which the adjustment mechanism 23 is for adjusting the orientation of the shin guard portion 25 with respect to the connection portion 24 of the shin support. Said adjustment mechanism 23 can be adapted to adjust the orientation of the shin guard portion 25 with respect to the connecting portion 24 of the same shin support 16 at least in the inner/outer direction IN-OUT with respect to the leg assembly 12L, 12R thereof. Such a mechanism for adjusting the shin support allows to adapt the exoskeleton to various bodies, making it suitable for a variety of users belonging to different morphotypes.

[072], The adjustment mechanism 23 can be configured to allow an adjustment of the orientation also in the flexion-extension direction FL-EX.

[073], In accordance with an embodiment, the adjustment mechanism 23 comprises a screwsocket type adjustment mechanism, in which the head of the adjustment screw 26 is accessible frontally and/or on the inner side 13 and/or on the outer side 14, when in operating conditions. Thereby, an adjustment can also be made to the exoskeleton 10 when worn, if necessary.

[074], As mentioned above, a vertical adjustment mechanism can be provided between the thigh support and the belt, comprising for example a slider 30 of the thigh support 15.

[075]. Preferably, the slider 30 of the thigh support 15 has an elongated body and is made in a single piece with the distal portion 28 of the same thigh support 15 forming the upper part of the doubleaxis hinge 20. [076], as well as a vertical adjustment mechanism can be provided between shin support 16 and foot 27 with bracket, which for example envisages relative movement between the connecting portion 24 and the shin guard portion 25 of the same shin support 16.

[077], As mentioned above, the double centre of rotation hinge 20 of the knee joint can be made of at least partially polymeric and/or polymer matrix composite material, preferably nylon-PA12, for example machined by means of moulding. The exoskeleton 10 in its entirety and/or the at least one leg assembly 12L; 12R can be made of polymeric material and/or polymer matrix composite, preferably nylon-PA12. It is well understood that screws, nuts, and/or reinforcements can be made of metallic material.

[078], As mentioned above, the shin support 16 preferably comprises a body extending substantially frontally along the leg assembly 12L; 12R, forming in a single piece a portion on the inner side and a portion on the outer side of the knee articulation joint KJ and can further form an ankle articulation with a foot portion 27, the ankle articulation also comprising an inner side and an outer side and being adapted to allow relative pronation/supination movement.

[079]. As mentioned above, the foot portion 27 can comprise a bracket comprising a bifurcation for wrapping a user's foot on the inner side and on the outer side.

[080]. As can be seen, thanks to the features described above, it is possible to meet the aforementioned needs, obtaining the aforementioned advantages, and in particular:

- an exoskeleton knee joint is made which approximates the kinematic mechanism of the human knee in a simple, and at the same time robust, manner, to make the invention suitable for large- scale production, also because it can be made with polymeric and/or polymer matrix materials, for example, by means of moulding techniques;

- in particular, the dimensioning of the double-axis hinge can be adjusted to obtain the desired performance, for example a parameter which can be chosen in the design phase is the spacing between the axes of rotation X1 and X2;

- at the same time, an unusual protection is provided to the user's knee, for example in military contexts, whereby the wearable exoskeleton can perform the function of armour in certain contexts, with an improved creation of the knee articulation; - it allows to obtain an optimal transfer path of forces through the knee joint KJ of the exoskeleton, both in extended and flexed conditions, even in the case of a knee flexed and resting on the ground;

- the exoskeleton is versatile and compatible with a variety of different users' bodies, without thereby entailing increased design and/or maintenance and/or retrofitting costs, while at the same time ensuring a certain level of ergonomics for the user;

- it avoids having to arrange crossed articulated quadrilaterals in the knee articulation of the exoskeleton.

[081]. A person skilled in the art can make numerous modifications, adaptations and replacement of elements with functionally equivalent elements to the embodiments described above, without however departing from the scope of the appended claims.