Exoskeleton for the assistance of polyarticular joints

DESCRIPTION

Field of the invention

The present invention relates to the field of exoskeletons for assistance to the movement of the humane joints .

In particular, the invention relates to an exoskeletal kinematic chain which is adapted to assist the movement of a polyarticular bone chain.

Description of the prior art

In the field of wearable robotics, the need is increasingly felt to find a simple and efficient architecture to create exoskeletons for the assistance of polyarticular joints, such as for example the set of phalanges that constitutes the finger of the hand or the vertebral column.

To date, although there are numerous exoskeletons that deal with the issue of mobilization, the technical problem that is still very much felt regards the size and weight of these devices, which prevent a truly natural experience of movement for the user.

Furthermore, the exoskeletons for the assistance to polyarticular joints appear to be very complex from the kinematic point of view, because they must have a rotation effect on anatomical multiaxial joints through a kinematics that is not aligned with the joint, but rather arranged above or laterally. This means that the movement of the finger or of the vertebral column must be guaranteed by respecting any passive self-alignment movements of the joints.

In this scenario, both to reduce the weight of the actuators and to provide a more natural use experience, the use of under-actuated robotic devices is increasingly essential .

An example of a under-actuation is shown in US5447403, in which a mesh structure is proposed for a prosthesis implemented under the hand. The essential concept is the use of pairs of cables that, properly directed by pulleys, allow to perform both the bending and extension movement of the prosthetic hand, in a similar way to what the articular tendons do in a human hand.

However, the solution proposed in D1 is strictly applicable only to orthotic robots and does not show in any way how this solution can be translated also to exoskeletal devices, in which anatomical and robotic joints cannot obviously coincide.

Summary of the invention

It is therefore a feature of the present invention to provide an exoskeletal kinematic chain which is adapted to assist the movement of a polyarticular bone chain. It is also a feature of the present invention to provide such an exoskeletal kinematic chain which allows the bone chain to move smoothly and naturally in both directions of rotation .

It is still a feature of the present invention to provide such an exoskeletal kinematic chain which is less heavy and bulky with respect to prior art devices.

These and other objects are achieved by an exoskeletal kinematic chain according to claims from 1 to 5.

According to another aspect of the invention, a back exoskeleton is claimed that uses the exoskeletal kinematic chain of claim 1.

According to a further aspect of the invention, a hand exoskeleton is claimed that uses the exoskeletal kinematic chain of claim 1.

Brief description of the drawings

Further characteristic and/or advantages of the present invention are more bright with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings in which:

— Fig. 1 shows a first exemplary embodiment of the kinematical chain according to the present invention in the straight configuration;

Fig. 1A shows the exemplary embodiment of Fig. 1 in the curved configuration; Fig. 2 shows a second exemplary embodiment of the kinematical chain according to the present invention in the straight configuration;

— Fig. 2A shows an exemplary embodiment of Fig. 2 in the curved configuration;

— Fig. 3 shows a third exemplary embodiment of the kinematical chain according to the present invention in the straight configuration;

— Fig. 3A shows an exemplary embodiment of Fig. 3 in the curved configuration;

— Fig. 4 shows a fourth exemplary embodiment of the kinematical chain according to the present invention in the straight configuration;

— Fig. 4A shows an exemplary embodiment of Fig. 4 in the curved configuration;

— Fig. 5 shows an implementation of the kinematical chain of Fig. 1 and 1A to an exoskeleton for the assistance of the vertebral column;

— Fig. 6 shows an implementation of the kinematical chain of Fig. 1 and 1A to an exoskeleton for assistance of a finger of the hand.

Description of a preferred exemplary embodiment

Figs. 1 and 1A show a first exemplary embodiment of the exoskeletal kinematic chain 100 arranged to assist the movement of a polyarticular bone chain 200, respectively in a straight configuration and in a curved configuration.

In particular, the polyarticular bone chain 200 can be diagrammatically divided into an anatomical engagement portion 205, a plurality of bone links 210 and a plurality of anatomical rotational joints 220. For example, the polyarticular bone chain 200 can be the vertebral column or a finger of the hand. Advantageously, in all the exemplary embodiments diagrammatically shown in Figs. 1 to 4A, only 3 bone links 210 are shown, but the principle remains unchanged in the case of a larger number of bone links 210.

The exoskeletal kinematic chain 100 comprises a frame 105 integrally connected to the anatomical engagement portion 205, a number i of exoskeletal links 110 equal to the number of the bone link 210, and a number j of exoskeletal rotational joints 120 equal to the number of the anatomical rotational joints 220. The first exoskeletal link 110 is also constrained to the frame 105.

In particular, the exoskeletal rotational joints 120 are located at a predetermined distances d _j . In the case of Fig. 1, the two exoskeletal rotational joints 120 are located at a distance d ₁ . Such distance remains unchanged with the rotation of the various links 110 and 210.

At each exoskeletal rotational joint 120 there is a pulley 125 arranged to rotate about a corresponding rotation axis Xj . A substantially inextensible cable 140 is integrally constrained to the exoskeletal link at the end of the kinematics exoskeleton 100 opposite to the frame 105 and is in contact with each pulley 125.

Furthermore, each exoskeletal link 110 is connected to a corresponding bone link 210 by a kinematic constraint 130, in such a way that each kinematic constraint 130 allows the transmission of at least one force component F _n orthogonal to the link to which the rotational movement is transferring.

If, for example, the bone chain 210 is a vertebral column, when it is stretched by a user the bone link 210 rotate moving from a curved configuration similar to that of Fig. 1A to a straight configuration similar to that of Fig. 1. In this case, the cable 140 is pulled and, by sliding on the pulleys 125, it causes the exoskeletal links 110 to rotate about the exoskeletal rotational joints 120. By means of the respective kinematic constraints 130, at least one force component F _n orthogonal to each bone link 210 is transmitted, helping the vertebral column to relax, relieving the muscular work of the user.

In particular, two cables 140 are provided, at opposite sides with respect to the exoskeletal links 110, which can be driven in an alternative way by an actuator in such a way that the exoskeletal links 110 can rotate clockwise or counter-clockwise depending on the need of the user. In particular, the exemplary embodiment of Figs. 1 and

1A provides that each kinematic constraint 130 comprises a T- shaped element 131, pivotally connected to a corresponding bone link 210, and a double pendulum, arranged to connect the T-shaped element 131 to a corresponding exoskeletal link 110. In particular, the double pendulum comprises two parallel rods 132 pivotally connected to the T-shaped element 131 and to the corresponding exoskeletal link 110 in such a way that there is no relative rotation between of them.

The exemplary embodiment of Figs. 2 and 2A provides instead that each kinematic constraint 130 comprises a slide 133, arranged to slide along a corresponding exoskeletal link 110, and a rod 134 arranged to connect the slide 133 to a corresponding bone link 210.

Alternatively, the exemplary embodiment of Figs. 3 and

3A provides that each kinematic constraint 130 comprises a slide 133 arranged to slide along a corresponding exoskeletal link (110), and a rod (134) arranged to connect the slide (133) to a corresponding bone link (210) .

In Figs. 4 and 4A show an alternative to the exemplary embodiment of Figs. 1 and 1A, where the double pendulum 132 is connected directly to the rotational joints 120 at the end of the exoskeletal link 110. Fig. 5 shows an example of application of the kinematical chain of Figs. 4 and 4A to an exoskeleton arranged to assist the movement of the vertebral column.

Fig. 6 shows an example of application of the kinematical chain of Figs. 4 and 4A to an exoskeleton arranged to assist the movement of the hand of a user.

The foregoing description some exemplary specific embodiments will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt in various applications the specific exemplary embodiments without further research and without parting from the invention, and, accordingly, it is meant that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realise the different functions described herein could have a different 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 .