Wearable robotic device for moving a user

DESCRIPTION Field of the invention

The present invention relates to the field of robotic devices for assisting the movement of a user.

In particular, the invention relates to a robotic device for the improvement of a prosthesis or an exoskeleton of a lower limb.

Description of the prior art

As known, different foot, ankle or knee prostheses may be prescribed to provide adequate limb amputees.

For a basic functionality, that is to get up and be able to walk, a SACH (Solid Ankle Cushioned Heel) foot is adopted. It is a stiff foot that offers only support and no energy contribution to walking. The amputee will have to compensate with the residual limbs for the absence of energy supply, at the expense of speed and metabolic consumption.

An increase in mobility can be obtained by using an

ESAR (Energy Storage And Return) foot, comprising an elastic carbon structure capable of storing mechanical energy during the first part of the support phase ( weight acceptance) of the walk and releasing it in the push phase (push-off) . However, a user's step requires between 0.2 and 0.29 J/Kg of mechanical energy and the aforementioned prostheses are able to generate between 0.06 and 0.11 J/Kg. The amount of energy missing must therefore be compensated by the other joint joints.

A possible alternative lies in the use of a mechanical actuator that inserts active power into the step cycle, transforming the passive prosthesis into an active one, and allowing the user not to have to compensate for the missing energy with muscle energy.

However, active prostheses have several disadvantages, since mechanical and electronic components are generally very complex and heavy. This entails higher costs and less reliability than passive prostheses. In addition, in the event of a malfunction or a lack of electricity, these prostheses lose all their functionality becoming rigid and heavy appendages that can also totally block the user's mobility.

US2013046218 describes a device for the accumulation and release of mechanical energy capable of assisting a user's walk. The device has a frame comprising an upper portion adapted to bind to the user's calf and a lower portion adapted to bind to the foot in a rotatable manner. A rotating clutch and an elastic element are also provided which allow the controlled release of mechanical energy to move the two portions of the frame.

However, in this device the release of mechanical energy takes place simply at the end of the accumulation phase and is in no way related to the patient's step phase. This means that the impulse provided by the elastic element is not synchronized with the user's pace, significantly reducing the quality of motor assistance provided by the device.

Summary of the invention

It is therefore a feature of the present invention to provide a robotic device for the movement of a user that has the practicality of using a prosthesis or a passive exoskeleton, who however does not need energy compensation by the user to obtain sufficient thrust to perform a step.

It is also a feature of the present invention to provide such a robotic device that can be used both on a foot prosthesis and on an exoskeleton for assisting a user's foot.

It is also a feature of the present invention to provide such a robotic device that can adapt to a variety of types of gait and of balancing the weight of a user.

These and other objects are achieved by a robotic device for the movement of a user according to claim 1.

Other aspects of the invention are described in the claims from 2 to 13. 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. 1A shows a kinematic diagram of the robotic device according to the present invention;

— Fig. IB shows the kinematic diagram of Fig. 1A when the relative movement s is equal to the predetermined threshold value s ^* and the robotic device passes from the first to the second configuration;

— Fig. 2A shows a kinematic diagram of the robotic device wherein the interface frame and the lower portion are connected by a laminar resilient element ;

— Fig. 2B shows a kinematic diagram of the robotic device wherein the interface frame and the lower portion are connected by a rotational joint;

— Fig. 3 diagrammatically shows a first exemplary embodiment of the robotic device wherein the lower portion and the resilient element make up a foot prosthesis;

— Fig. 4A shows the embodiment of Fig. 3 in the first configuration during the deformation of the elastic element, until it reaches the threshold value;

— Fig. 4B shows the embodiment of Fig. 3 in the moment in which, passing from the first to the second configuration, there is an instantaneous releasing of elastic energy;

— Fig. 5 shows a possible real application of the embodiment of Fig. 3;

— Fig. 6A shows an embodiment of the robotic device having a linear spring and a rotational switching device ;

— Fig. 6B shows an embodiment of the robotic device having a linear spring and a linear switching device ;

— Fig. 7A shows an embodiment of the robotic device having a torsional spring and a linear switching device ;

— Fig. 7B shows an embodiment of the robotic device having a torsional spring and a rotational switching device;

— Fig. 8 shows an embodiment of the robotic device similar to that of Fig. 6A wherein the lower portion is a belt of engagement to a foot of the user . Description of a preferred exemplary embodiment

With reference to Figs. 1A and IB, the robotic device 100, according to the present invention, comprises an interface frame 105, arranged to connect the robotic device 100 to a lower limb or to a lower limb prosthesis, a lower portion 110 and a resilient element 140 having a first end 141 connected to the interface frame 105 and a second end 142 connected to the lower portion 110.

Considering an axis x integral to the interface frame 105 and an axis y integral to the lower portion 110, the resilient element 140 can be deformed as a function of an angular variation Q between the axis x and the axis y, as shown in Fig. IB.

The robotic device 100 also comprises a switching device 120 comprising a first element 121, connected to the interface frame 105, and a second element 122, connected to the lower portion 110. In particular, the first and the second element 121,122 are adapted to carry out a relative movement s as a function of the angular variation Q between the axis x and the axis y.

This way, when the angular variation Q increases, the resilient element 140 deforms storing elastic energy and, at the same time, increases also the relative movement s between the elements 121 and 122. In this step the robotic device 100 is in a first configuration, or energy storage configuration. With reference to Fig. 1,B, when the relative movement s is equal to a predetermined threshold value s ^* , the robotic device 100 is configured to pass from the first configuration to a second configuration, where the resilient element 140 instantly releases elastic energy creating an angular moment M _ei arranged to oppose the increasing of the angular variation Q.

In Fig. 2A a kinematic diagram of the robotic device 100 is shown wherein the interface frame 105 and the lower portion 110 are connected by a laminar resilient element 140. Such kinematic diagram is at the basis of the operation of the foot prosthesis diagrammatically shown in Fig. 3 and, in a way more detailed, for example, in the embodiment of Fig. 5, wherein the lower portion 110 and the resilient element 140 make up a passive foot prosthesis, present in prior art.

In particular, in Figs. 3 and 5, the first element 121 of the switching device 120 comprises a cylindrical housing 121a, whereas the second element 122 comprises a free wheel 122a and a rigid arm 122b comprising a first end 122b' connected to the lower portion 110 and a second end 122b' ' connected to the free wheel 122a.

The switching device 120 also comprises a plurality of balls 123 that, with the free wheel 122a and the cylindrical housing 121a, provides a unidirectional clutch where the free wheel 122a can carry out a rotational relative movement s with respect to the cylindrical housing 121a only in one direction of rotation, in particular in Fig. 3 counter clockwise with respect to the plane of the sheet.

In the figures 4A and 4B are shown, respectively, the first configuration, of storage of elastic energy, and the second configuration, of instantaneous release of this energy. For the sake of clearness of the drawing, the axis y is kept with a constant direction during the deformation of the resilient element 140, whereas the axis x changes its own direction, becoming the axis x', allowing to highlight the angular variation Q.

In particular, in Fig. 4A shows the successive deformations of the resilient element 140 due to the movement of the user's weight on the lower portion 110. During the deformation, and the increasing the angular variation Q, the rigid arm 122b pushes towards the frame 105 its second end 122b' ' bringing the free wheel 122a to carry out a relative rotation s in the only direction in which the rotation is allowed by the unidirectional clutch.

If the deformation stopped before the movement s reached the threshold value s ^* , the switching device 120, owing to the unidirectional clutch, would prevent the resilient element 140 from resuming its shape at rest. Therefore, as long as the robotic device 100 is in the first configuration, i.e. before the movement s reaches the threshold s ^* , the resilient element 140 accumulates elastic energy irreversibly .

when the angular variation Q is such as to allow the second end 122b' ' to make a relative movement s>s*, i.e. when the rigid arm 122b overlaps the centre of the free wheel 122a, the robotic device 100 passes into the second configuration, as shown in Fig. 4B, instantly releasing the accumulated elastic energy.

This elastic energy, released impulsively, allows to provide the user with a sufficient push to take the step without having to compensate for the missing energy with muscle energy or through an external actuator. In fact, with respect to a passive resilient foot prosthesis of the prior art, the embodiment of the device 100 of Figs. 3-5, owing to the presence of the switching device 120, is adapted to control the release of the elastic energy and to supply it to the user exactly in the instant wherein the pushing step of the foot begins, effectively replacing the impulse generally provided by the muscles of the leg.

With reference even to Fig. 5, the device 100 can also comprise adjustment means, such as the elongated hole 125, capable of adjusting the threshold value s ^* , at which an impulsive release of elastic energy is obtained. This makes it possible to adapt the robotic device 100 to different types of walking and balancing the weight of a user. With reference to Figs. 6A, 6B, 7A and 7B, some variants of the robotic device 100 are shown, in which different embodiments of the resilient element 140 and of the switching device 120 and different combinations of these embodiments are provided.

All the embodiments of Figs. 6A, 6B, 7A and 7B may have application as an exoskeleton or as a foot prosthesis, depending on whether the lower portion 110 is, respectively, a means of engagement with the foot of the user or a prosthetic foot.

In particular, in Fig. 6A an embodiment is shown similar to that of Figs. 3-5, wherein a linear spring 140 and a "clutch" type switching device 120, i.e. comprising a rotational unidirectional clutch, are provided.

In Fig. 6B instead an embodiment is shown wherein the switching device 120 is of the type linear and comprises a rigid arm 122b, a wedge element 124 and two rotating elements 121b having a profile such as to allows a clamping by friction of the rotating elements 121b on said rigid arm 122b in a single direction of relative movement. For example, the rotating elements 121b may have logarithmic spiral shape. When there is an angular variation Q of the axis y, and therefore of the portion 110, arm 122b moves upwards compressing the spring 140. In particular, the rigid arm 122b carries out a translation s with respect to the rotating elements 121b that, owing to the particular spiral-shaped profile, allow this translation upwards but prevent it in an opposite direction owing to the clamping friction.

As in the previous embodiment, therefore, as long as the robotic device 100 is in the first configuration, i.e. before the movement s reaches the threshold s ^* , the resilient element 140 accumulates elastic energy irreversibly. When the translation s is such that the wedge element 124 comes to touch the rotating elements 121b, there is s = s ^* and the rotating elements 121b loose contact with the rigid arm 122b, instantly allowing the translation downwards and therefore the release of elastic energy necessary for the user's movement .

The elongated hole 125 also allows you to adjust the relative position between the rigid arm 122b and the wedge element 124, allowing you to change the threshold value s ^* and to adapt it to the specific needs of the user.

In Fig. 7A there is another embodiment where the resilient element 140 is a torsional spring, whereas the switching device 120 comprises a pawl 121c and a gear 122c arranged to form a ratchet mechanism. Even in this case, when there is an angular variation Q, the spring 140 accumulates elastic energy and the toothed wheel 122c can rotate only in one direction due to the pawl 121c that is engages on the teeth of the wheel itself. When then the angular variation Q is such that the portion 110 contacts the ball 121c' , the threshold s ^* is reached and the pawl 121c rises, allowing the instantaneous release of the elastic energy.

In Fig. 7B there is a further embodiment which combines the torsional spring 140 of Fig. 7A with the linear switching device 120 of Fig. 6B.

In Fig. 8 a possible embodiment is shown of the present invention, similar to that of Fig. 6A, wherein the lower portion 120 is a belt of engagement to a foot of the user. Alternatively, the lower portion 120 can be a shoe, or any other element that allows to make the axis y integral with the foot of the 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 .