Patent Description:
In particular, the invention introduces a device, preferably prosthetic, configured to control a rotation of a robotic limb (in particular a portion of a limb such as a leg) relative to a second element such as a torso or a different portion of a limb such as a thigh. Preferably the joint is a prosthetic knee.

Currently in the field of robotic prosthetics, one of the biggest problems is balancing product design between performance (in terms of usable torque, maximum actuator speed and energy consumption) and the overall dimensions and weight of the product.

An obvious example of such a problem lies in prostheses simulating a preferably propulsive joint where there are considerable difficulties in fulfilling the performance diversity requirements in the various phases of movement.

This is convenient in a propulsive knee joint where pitch and bulk requirements clash with functional ones. In fact, the human quadriceps, which actuates the knee joint, on a fast walk averages a peak power of <NUM> W/kg (<NUM> watts for an <NUM> patient) while on an incline this number increases significantly to reach an average peak power of <NUM> W/kg (<NUM> watts for an <NUM> patient).

In an attempt to address this, the products currently on the market (e.g. Power Knee, Ossur) have unbalanced performance towards propulsive torque, to the detriment of maximum joint speed.

The known technique described includes some major drawbacks.

In particular, the well-known active prosthetic joints are bulky and heavy, so an operator usually prefers passive (i.e. non-motorised) prosthetic joints that are light and unobtrusive.

This aspect, and thus the preference for passive prosthetic joints, is accentuated by the considerable difficulties of control and management encountered by the operator.

A not insignificant drawback is that the well-known active prosthetic joints have particularly complex mechanics and therefore have high costs in both production and maintenance.

In this situation, the technical task at the basis of the present invention is to devise an active prosthetic joint that can substantially obviate at least part of the aforementioned drawbacks. <CIT> shows a prosthetic joint configured to mutually rotate a first prosthesis and a second prosthesis according to the preamble of claim <NUM>.

Within this technical task, it is an important aim of the invention to obtain a lightweight and space-saving active prosthetic joint.

Another important aim of the invention is to realise an active prosthetic joint characterised by ease of use and featuring relatively simple mechanics and low production and maintenance costs.

The specified technical task and purposes are achieved by a prosthetic joint as claimed in the attached claim <NUM>. Examples of preferred embodiments are described in the dependent claims.

The features and advantages of the invention are clarified below by a detailed description of preferred embodiments of the invention, with reference to the accompanying drawings, in which:.

Unless otherwise indicated, "perpendicular", "transverse", "parallel" or "normal" or other terms of geometric positioning between geometric elements (e.g. axes, directions and straight lines) are to be understood with reference to their reciprocal geometric position between the corresponding projections. These projections are defined on a single plane parallel to the plane(s) of location of said geometric elements.

With reference to the Figures, the prosthetic joint according to the invention is indicated globally by the number <NUM>.

It is configured to be connected to a first prosthesis 1a and a second prosthesis 1b and in detail interposed between said prostheses 1a and 1b.

The first prosthesis 1a may be identified in a torso or a limb (particularly a portion of a limb such as a thigh). In some, the first prosthesis 1a may be a prosthetic socket. The second prosthesis 1b can be identified in a robotic limb and in particular in a portion of a limb such as a leg and/or a foot.

It is configured to command a rotation between a first prosthesis 1a and a second prosthesis 1b. In detail, it is configured to command a rotation of the first prosthesis 1a with respect to the second prosthesis 1b and appropriately with respect to the same joint <NUM>.

Preferably the joint <NUM> is a knee that allows rotation with respect to the knee prosthesis and the femoral stump.

The prosthetic joint <NUM> can define an angle of rotation, i.e. a maximum amplitude of rotation that can be performed by the same joint <NUM>. This angle can be almost less than <NUM>° in detail to <NUM>° and appropriately between <NUM>° and <NUM>°.

The prosthetic joint <NUM> may comprise an attachment <NUM> of the joint <NUM> to the first prosthesis 1a and appropriately an additional attachment <NUM> of the joint <NUM> to the second prosthesis 1b. The attachment <NUM> is between joint <NUM> and first prosthesis 1a and the additional attachment <NUM> between joint <NUM> and second prosthesis 1b.

For example, the attachment <NUM> may be a female pyramid or other attachment configured to allow connection with a rigid prosthetic foot.

The prosthetic joint <NUM> may include a movement member <NUM> configured to control a rotation between attachments <NUM> and <NUM> and thus between prostheses 1a and 1b. More precisely, the movement member <NUM> is configured to control a rotation of the first joint <NUM> and <NUM> and thus of the first prosthesis 1a with respect to the second prosthesis 1b and appropriately with respect to the same joint <NUM>.

The transmission member <NUM> can define a thrust torque for said rotation. For example, in the case of a prosthetic joint <NUM> identifiable in a knee, the thrust torque defines the power that the joint <NUM> expresses by allowing, for example, a walk or a climb.

The member <NUM> can define a rotation speed for said rotation. For example, in the case of the joint <NUM> identifiable in a knee, this speed represents the speed that prosthetic joint <NUM> expresses during, for example, a walk or a climb.

The transmission member <NUM> may comprise a first actuator <NUM> defining for this rotation a first torque and appropriately a first speed.

The first torque identifies the maximum torque that can be expressed by the first actuator <NUM>. The first torque can be substantially less than <NUM>, in detail roughly between <NUM> and <NUM>. More specifically, it is substantially equal to <NUM>. The first speed identifies the maximum rotation speed when the first actuator <NUM> expresses said first torque.

It can be substantially at least equal to <NUM> rpm, in detail roughly between <NUM> rpm and <NUM> rpm. More specifically, the first speed is essentially equal to <NUM> rpm.

The first actuator <NUM> may comprise a first preferably electric motor and appropriately a first preferably harmonic gearbox.

The transmission member <NUM> may include a second actuator <NUM> defining for this rotation a second torque and appropriately a second speed.

The second torque identifies the maximum torque that can be expressed by the second actuator <NUM>.

The second pair may be substantially larger than the first pair.

It can be substantially at least equal to <NUM>, in detail roughly between <NUM> and <NUM>. More specifically, the second torque can be substantially equal to <NUM>. The second speed identifies the maximum rotation speed when the second actuator <NUM> expresses said second torque.

The second speed may be substantially lower than the first speed.

It can be substantially less than <NUM> rpm, in detail roughly between <NUM> rpm and <NUM> rpm. More specifically, the second speed is essentially <NUM> rpm.

To be more precise, it should be noted that preferably the torque and speed numbers mentioned above are peak values that the actuators can generate and therefore not a fixed torque.

The second actuator <NUM> may comprise a second preferably electric motor and appropriately a second preferably harmonic gear.

Transmission gear <NUM> may include a kinematic mechanism <NUM> configured to utilise actuators <NUM> and <NUM> to drive said rotation.

The kinematic mechanism <NUM> is configured to selectively place actuators <NUM> and <NUM> in kinematic connection (i.e., a connection such that the motion exiting at least one actuator <NUM> and/or <NUM> drives said rotation) with the first attachment <NUM>.

Preferably it is configured to define a low-thrust configuration and a high-thrust configuration.

In this configuration, the first actuator <NUM> is kinematically connected to the attachment <NUM> and the second actuator <NUM> is kinematically disconnected so that only the first actuator <NUM> controls this rotation.

Therefore, in this configuration, the first actuator <NUM> can rotate appropriately by an angle almost no greater than said angle of rotation. The second <NUM> remains substantially stationary.

In the low-thrust configuration, the maximum rotational torque that can be expressed by drive <NUM> can be substantially no higher than the first torque.

Preferably in the low-thrust configuration, the maximum rotational speed that can be expressed by the transmission member <NUM> is substantially no higher than the first speed.

In the high-thrust configuration, the kinematic mechanism <NUM> places both actuators <NUM> and <NUM> in kinematic connection with port <NUM> so that both the first actuator <NUM> and the second actuator <NUM> control this rotation.

In this configuration, the actuators <NUM> and <NUM> can rotate simultaneously and in detail with the same speed for at least said angle of rotation. Preferably in the high thrust configuration the actuators <NUM> and <NUM> rotate in one direction simultaneously and suitably with the same rotation speed for at least said angle of rotation. In the other direction the actuators <NUM> and <NUM> can rotate independently of each other for at least said angle of rotation.

In the high-thrust configuration, the maximum rotational torque that can be expressed by the transmission member <NUM> can be substantially higher than the first torque and in detail substantially between the first torque and the sum of said first torque and said second torque.

Preferably in the high-thrust configuration, the maximum rotational speed that can be expressed by the transmission member <NUM> is substantially lower than the first and in detail almost no higher than the second speed.

In summary, the kinematic mechanism <NUM> is configured to selectively define or release a rotational constraint between the actuators <NUM> and <NUM>. In low-thrust configuration, the kinematic motion <NUM> does not define the rotational constraint between actuators <NUM> and <NUM>, whereas in high-thrust configuration it defines the rotational constraint between the actuators <NUM> and <NUM>.

Preferably, said kinematic mechanism <NUM> is configured to selectively define or release a rotational constraint in only one direction of rotation.

The kinematic mechanism <NUM> may comprise a first wheel <NUM> configured to receive output motion from the first actuator <NUM>; a second wheel <NUM> configured to receive output motion from the second actuator <NUM>; and a connector <NUM> configured to selectively allow or prevent a passage of motion between the wheels <NUM> and <NUM>. The first wheel <NUM> can be attached to a coupling and in particular to the first attachment <NUM>.

Preferably the wheels <NUM> and <NUM> are pulleys.

The second wheel can have a substantially larger radius than the first wheel.

The connector <NUM> is configured to allow the second wheel <NUM> (i.e., the second actuator <NUM>) to control rotation between the attachments <NUM> and <NUM>, and to be precise between the prosthetic joint <NUM> and the prosthesis 1a exclusively via the first wheel <NUM> (i.e., the first actuator <NUM>).

In a low-thrust configuration, the connector <NUM> prevents a passage of motion between the wheels <NUM> and <NUM> preferably for at least said angle of rotation. It may thus allow the first wheel <NUM> to rotate (suitably by at least said angle of rotation) while leaving the second wheel <NUM> substantially stationary.

In a high thrust configuration, the connector <NUM> allows a passage of motion between the wheels <NUM> and <NUM> preferably for at least said angle of rotation. It may thus force the wheels <NUM> and <NUM> to rotate synchronously by angles proportional to each other in accordance with the rays and/or suitably for at least said angle of rotation.

In a preferred form of non-limiting embodiment, the connector <NUM> can be identified in at least one cable subtended between the wheels <NUM> and <NUM>, and appropriately each wheel <NUM> and <NUM> can be a pulley to which said cable is tied at the throat.

In order to have a passage of motion between the wheels <NUM> and <NUM> (i.e. between the actuators <NUM> and <NUM>) in only one direction of rotation, the connector <NUM> can be identified as a single cable with one end integral with the first wheel <NUM>, the other end integral with the second wheel <NUM> and a single subtended portion between the two wheels <NUM> and <NUM>.

The cable can be made of synthetic fibres such as high-modulus polyethylene (HMPE), also known as ultra-high molecular weight polyethylene (UHMWPE, UHMW) commercially known under the brand name Dyneema®.

The length of the connector <NUM> can be substantially equal to the distance between the rotation axes of the wheels <NUM> and <NUM>, to the portion of cable wound on each wheel; and to the arc defined by the radius of a wheel <NUM> and <NUM> (in detail the second one) multiplied by the rotation angle of said wheel corresponding to the rotation angle of the prosthetic joint <NUM>.

In a low-thrust configuration, the cable (i.e. connector <NUM>) can be slack so that the first wheel <NUM> can rotate relative to the second wheel <NUM> by exploiting this condition of the cable. In a high thrust configuration, the cable may be taut so that a rotation between the prosthesis 1a and 1b is only possible by producing a synchronous movement of the wheels <NUM> and <NUM>.

In order to hold the cable (i.e. the connector <NUM>) in the grooves, the kinematic mechanism <NUM> may comprise a tensioner <NUM> configured to hold the connector <NUM> in place (in detail in the grooves).

The tensioner <NUM> is configured to provide the cable (i.e. the connector <NUM>) with a minimum voltage substantially lower than the standstill voltage of the second actuator <NUM>, i.e. lower than the resistance of the second actuator <NUM> to change from a standstill condition to a movement condition.

The tensioner <NUM> may comprise an arm 434a integral with the coupling <NUM>, a thrust wheel 434b on the connector <NUM>; an additional arm 434c hinging the thrust wheel 434b cantilevered from the arm 434ab; and a spring configured to work in opposition to a cable tension. Said spring being preloaded so as to provide said minimum tension to the cable.

The functioning of the active prosthetic joint <NUM> described above in structural terms is as follows.

Initially, the prosthetic joint <NUM> is in a low thrust configuration and therefore the kinematic mechanism <NUM> does not define the rotational constraint between actuators <NUM> and <NUM>. The cable (i.e. connector <NUM>) is slack leaving the second actuator <NUM> kinematically disconnected from both actuators <NUM> and <NUM> the only first actuator <NUM> kinematically connected to an attachment <NUM>.

In this configuration, the prosthetic joint <NUM> can express a thrust torque and velocity that are substantially proportional to the first torque and velocity, respectively. When the user must, for example, confront a climb, he commands the joint <NUM> to switch to a high-thrust configuration.

Therefore, the second actuator <NUM> rotates the second wheel <NUM> which wraps around the connector <NUM> tensioning it. Appropriately, during this time the first actuator <NUM> and thus the first wheel <NUM> can remain substantially stationary.

This operation is performed in opposition to the tensioner <NUM> as the connector <NUM>, by pressing on the thrust wheel 434b, rotates the additional arm 434c in relation to the arm 434a in opposition to the spring.

At this point, the kinematic mechanism <NUM> defines the rotational constraint between actuators <NUM> and <NUM>. The cable (i.e. connector <NUM>) is tensioned by kinematically connecting both connections <NUM> and <NUM>.

In detail, the actuators <NUM> and <NUM> are constrained by the kinematic mechanism <NUM> to rotate in unison in one direction of rotation for at least said angle of rotation. Thus, the actuators <NUM> and <NUM> can discharge their torque on the joint <NUM>, which is then able to express a maximum rotational torque given by the sum of the first and second torque.

It should also be noted that since both actuators <NUM> and <NUM> are connected to each other, the maximum achievable speed is limited to that of the second actuator <NUM>.

Once the high-thrust configuration is reached, the user can tackle the ascent.

Once the ascent is complete, there is a return to a low-thrust configuration.

The second actuator <NUM> rotates the second wheel <NUM> in the opposite direction to the previous one by unwinding the connector <NUM>, which becomes slack. Appropriately at this time the first actuator <NUM> and thus the first wheel <NUM> can remain substantially stationary.

At the same time, the tensioner <NUM>, utilising the energy previously stored, tensions the connector <NUM>) to said minimum voltage, i.e. to a voltage lower than that at which the second actuator <NUM> can remain stationary while the first actuator <NUM> moves.

The invention introduces an innovative movement procedure implementable by means of the active prosthetic joint <NUM> according to the invention.

The movement process may include at least one movement phase in which the prosthetic joint <NUM> is in a low thrust configuration or in a high thrust configuration.

In each movement phase the movement member <NUM>, using the first actuator <NUM> and in some cases the second actuator <NUM>, moves the joint <NUM> and thus a rotation between the prostheses 1a and 1b and in detail between the prosthetic joint <NUM> and the prosthesis 1a.

Preferably, it comprises several movement phases that differ from each other in the configuration assumed by the prosthetic joint <NUM>. For example, the procedure may sequentially comprise a first movement phase with joint <NUM> in a low thrust configuration, a second handling phase with joint <NUM> in a high-thrust configuration, and a third movement phase with the joint <NUM> in a low thrust configuration.

In the first and third thrust phase, only the first actuator <NUM> is kinematically connected to attachment <NUM> and thus only it controls the rotation between prostheses 1a and 1b and thus between prosthetic joint <NUM> and prosthesis 1a.

In the second thrust phase, both actuators <NUM> and <NUM> are kinematically connected to at least one attachment <NUM> and/or <NUM>, and thus both the first actuator <NUM> and the second actuator <NUM> control said rotation.

The movement process may include at least one configuration change phase in which the prosthetic joint <NUM> changes its configuration between low thrust and high thrust.

In each configuration change step, the kinematic mechanism <NUM> selectively defines or releases the aforementioned rotational constraint between actuators <NUM> and <NUM> by controlling a reciprocal motion between the actuators <NUM> and <NUM>.

This is performed by means of a rotation between the actuators <NUM> re <NUM> and thus between the wheels <NUM> and <NUM>, which respectively make the connector <NUM> tight or slack.

Preferably, the process comprises a configuration change phase interposed between two adjacent movement phases. Thus, with reference to the aforementioned example, the procedure may sequentially comprise a first handling phase with the joint <NUM> in a low thrust configuration; a first configuration change phase in which the joint <NUM> switches from a low thrust configuration to a high thrust configuration; a second movement phase in which the prosthetic joint <NUM> is in a high thrust configuration; a second configuration change phase in which the joint <NUM> switches from a high thrust configuration to a low thrust configuration; and a third handling phase in which the joint <NUM> is in a low thrust configuration.

In the first phase of the configuration change, the second actuator <NUM> commands a rotation of the second wheel <NUM>, which wraps the connector <NUM> by tensioning it and thus realising said rotational constraint between the actuators <NUM> and <NUM>. In this first phase, the first actuator <NUM> and thus the first wheel <NUM> can remain stationary. In the second configuration change phase, the second actuator <NUM> commands a rotation of the second wheel <NUM> in the opposite direction to that of the first configuration change phase. Said rotation of the second wheel <NUM> unwinds the connector <NUM> by keeping it and thereby releasing said rotational constraint. In this second phase, the first actuator <NUM> and thus the first wheel <NUM> can remain stationary.

The active prosthetic joint <NUM> and thus the movement process according to the invention achieve important advantages.

In fact, the prosthetic joint <NUM> and thus the handling procedure are able to vary their configuration between low thrust and high thrust in a simple and practical way, ensuring optimal power according to the power required for the specific activity. One advantage is that the prosthetic joint <NUM> and thus the movement procedure are simple and convenient to operate and use.

Another important advantage is the fact that, compared to known active prosthetic joints, the prosthetic joint <NUM> is smaller in size and in detail almost comparable to a normal joint.

A not insignificant advantage is to be found in the reduced weight of the prosthetic joint <NUM>.

Claim 1:
Prosthetic joint (<NUM>) configured to mutually rotate a first prosthesis (1a) and a second prosthesis (1b) and comprising:
- an attachment (<NUM>) of said prosthetic joint (<NUM>) to said first prosthesis 1a);
- an additional attachment (<NUM>) of said prosthetic joint (<NUM>) to said second prosthesis (1b);
- a movement member (<NUM>) configured to control a rotation between said attachments (<NUM>, <NUM>) and therefore between said prostheses (1a, 1b) defining a thrust torque for said rotation;
and wherein said movement member (<NUM>) comprises
- a first actuator (<NUM>) defining a first pair for said rotation;
- a second actuator (<NUM>) defining for said rotation a second torque substantially greater than said first torque; and
- a kinematic mechanism (<NUM>) configured to exploit said actuators (<NUM>, <NUM>) to control said rotation; characterised in that
said kinematic mechanism (<NUM>) is configured to selectively define or dissolve a rotational constraint between said actuators (<NUM>, <NUM>) by defining
o a low thrust configuration in which said first actuator (<NUM>) is kinematically connected to said attachment (<NUM>) and said second actuator (<NUM>) is kinematically disconnected from said attachment (<NUM>) so that exclusively said first actuator (<NUM>) controls said rotation defining a maximum rotation torque substantially not greater than said first torque and
o a high thrust configuration in which both said actuators (<NUM>, <NUM>) are kinematically connected to said attachment (<NUM>) so that both said first actuator (<NUM>) and said second actuator (<NUM>) control said rotation defining a maximum rotation torque substantially comprised between said first pair and the sum of said first pair and said second pair.