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

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 <NUM> and <NUM> J/Kg of mechanical energy and the aforementioned prostheses are able to generate between <NUM> and <NUM> 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.

<CIT> 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.

<CIT> forms also part of the prior art disclosing the preamble of claim <NUM>.

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.

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 <NUM>.

Other aspects of the invention are described in the claims from <NUM> to <NUM>.

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:.

With reference to <FIG>, the robotic device <NUM>, according to the present invention, comprises an interface frame <NUM>, arranged to connect the robotic device <NUM> to a lower limb or to a lower limb prosthesis, a lower portion <NUM> and a resilient element <NUM> having a first end <NUM> connected to the interface frame <NUM> and a second end <NUM> connected to the lower portion <NUM>.

Considering an axis x integral to the interface frame <NUM> and an axis y integral to the lower portion <NUM>, the resilient element <NUM> can be deformed as a function of an angular variation θ between the axis x and the axis y, as shown in <FIG>.

The robotic device <NUM> also comprises a switching device <NUM> comprising a first element <NUM>, connected to the interface frame <NUM>, and a second element <NUM>, connected to the lower portion <NUM>. In particular, the first and the second element <NUM>,<NUM> are adapted to carry out a relative movement s as a function of the angular variation θ between the axis x and the axis y.

This way, when the angular variation θ increases, the resilient element <NUM> deforms storing elastic energy and, at the same time, increases also the relative movement s between the elements <NUM> and <NUM>. In this step the robotic device <NUM> is in a first configuration, or energy storage configuration.

With reference to <FIG>, when the relative movement s is equal to a predetermined threshold value s*, the robotic device <NUM> is configured to pass from the first configuration to a second configuration, where the resilient element <NUM> instantly releases elastic energy creating an angular moment Mel arranged to oppose the increasing of the angular variation θ.

In <FIG> a kinematic diagram of the robotic device <NUM> is shown wherein the interface frame <NUM> and the lower portion <NUM> are connected by a laminar resilient element <NUM>. Such kinematic diagram is at the basis of the operation of the foot prosthesis diagrammatically shown in <FIG> and, in a way more detailed, for example, in the embodiment of <FIG>, wherein the lower portion <NUM> and the resilient element <NUM> make up a passive foot prosthesis, present in prior art.

In particular, in <FIG> and <FIG>, the first element <NUM> of the switching device <NUM> comprises a cylindrical housing 121a, whereas the second element <NUM> comprises a free wheel 122a and a rigid arm 122b comprising a first end 122b' connected to the lower portion <NUM> and a second end 122b'' connected to the free wheel 122a.

The switching device <NUM> also comprises a plurality of balls <NUM> 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> counter clockwise with respect to the plane of the sheet.

In the <FIG> 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 <NUM>, whereas the axis x changes its own direction, becoming the axis x', allowing to highlight the angular variation θ.

In particular, in <FIG> shows the successive deformations of the resilient element <NUM> due to the movement of the user's weight on the lower portion <NUM>. During the deformation, and the increasing the angular variation θ, the rigid arm 122b pushes towards the frame <NUM> 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 <NUM>, owing to the unidirectional clutch, would prevent the resilient element <NUM> from resuming its shape at rest. Therefore, as long as the robotic device <NUM> is in the first configuration, i.e. before the movement s reaches the threshold s*, the resilient element <NUM> accumulates elastic energy irreversibly.

when the angular variation θ 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 <NUM> passes into the second configuration, as shown in <FIG>, 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 <NUM> of <FIG>, owing to the presence of the switching device <NUM>, 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>, the device <NUM> can also comprise adjustment means, such as the elongated hole <NUM>, 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 <NUM> to different types of walking and balancing the weight of a user.

With reference to <FIG>, <FIG>, some variants of the robotic device <NUM> are shown, in which different embodiments of the resilient element <NUM> and of the switching device <NUM> and different combinations of these embodiments are provided.

All the embodiments of <FIG>, <FIG> may have application as an exoskeleton or as a foot prosthesis, depending on whether the lower portion <NUM> is, respectively, a means of engagement with the foot of the user or a prosthetic foot.

In particular, in <FIG> an embodiment is shown similar to that of <FIG>, wherein a linear spring <NUM> and a "clutch" type switching device <NUM>, i.e. comprising a rotational unidirectional clutch, are provided.

In <FIG> instead an embodiment is shown wherein the switching device <NUM> is of the type linear and comprises a rigid arm 122b, a wedge element <NUM> 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 θ of the axis y, and therefore of the portion <NUM>, arm 122b moves upwards compressing the spring <NUM>. 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 <NUM> is in the first configuration, i.e. before the movement s reaches the threshold s*, the resilient element <NUM> accumulates elastic energy irreversibly. When the translation s is such that the wedge element <NUM> 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 <NUM> also allows you to adjust the relative position between the rigid arm 122b and the wedge element <NUM>, allowing you to change the threshold value s* and to adapt it to the specific needs of the user.

In <FIG> there is another embodiment where the resilient element <NUM> is a torsional spring, whereas the switching device <NUM> comprises a pawl 121c and a gear 122c arranged to form a ratchet mechanism. Even in this case, when there is an angular variation θ, the spring <NUM> 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 θ is such that the portion <NUM> contacts the ball 121c', the threshold s* is reached and the pawl 121c rises, allowing the instantaneous release of the elastic energy.

In <FIG> there is a further embodiment which combines the torsional spring <NUM> of <FIG> with the linear switching device <NUM> of <FIG>.

Claim 1:
A robotic device (<NUM>) for the movement of a user, said robotic device (<NUM>) comprising:
- an interface frame (<NUM>) arranged to connect said robotic device (<NUM>) to a lower limb or to a lower limb prosthesis, said interface frame (<NUM>) being integral to an axis x;
- a lower portion (<NUM>) integral to an axis y;
- a resilient element (<NUM>) having a first end (<NUM>) connected to said interface frame (<NUM>) and a second end (<NUM>) connected to said lower portion (<NUM>), said resilient element (<NUM>) being arranged to deform as a function of an angular variation θ between said axis x and said axis y;
- a switching device (<NUM>) comprising a first element (<NUM>), connected to said interface frame (<NUM>), and a second element (<NUM>), connected to said lower portion (<NUM>), said first and second element (<NUM>,<NUM>) arranged to carry out a relative movement s as a function of said angular variation θ between said axis x and said axis y; said robotic device (<NUM>) being configured in such a way that:
- when said relative movement s is less than a predetermined threshold value s* and said angular variation θ increases, said robotic device (<NUM>) is in a first configuration and said resilient element (<NUM>) deforms storing elastic energy, said switching device (<NUM>) being configured in such a way that in said first configuration said relative movement s can take place only in one direction of motion; said robotic device (<NUM>) being characterized in that it is configured in such a way that:
- when said relative movement s is equal to said predetermined threshold value s*, as consequence of the condition s = s* said robotic device (<NUM>) passes in a second configuration and said resilient element (<NUM>) instantly releases elastic energy creating an angular moment Mel arranged to oppose the increasing of said angular variation θ.